JP3908492B2 - Multi-frequency accommodation type crystal unit - Google Patents

Description

[0001]
The present invention relates to an industrial technical field of a multi-frequency accommodation type crystal resonator in which a plurality of crystal pieces are hermetically sealed in the same container, and in particular, a quartz resonator having a multi-function by accommodating an AT cut and a tuning fork type. About.
[0002]
[Prior art]
BACKGROUND OF THE INVENTION A crystal resonator is incorporated in an oscillator as a frequency and time reference source, and is incorporated in various electronic devices. For example, in recent small mobile electronic devices including mobile phones and the like, different types of crystal resonators in which the communication frequency is AT cut and the clock signal is a tuning fork type are separately incorporated. In these cases, since miniaturization of the electronic device is hindered, for example, there is a proposal for accommodating both types of crystal pieces in the same container to reduce the size (see: Japanese Patent Application Laid-Open No. 2000-349181 and Japanese Patent Application No. 2001-236503). issue).
[0003]
(Example of Prior Art) FIGS. 6 to 8 are views for explaining one conventional example. 6 is a cross-sectional view of the crystal resonator, FIG. 7 is a bottom view thereof, and FIG. 8 (ab) is a plan view of each crystal piece.
The crystal resonator is formed by sealing and enclosing two types of crystal pieces 2 and 3 of a tuning fork type and an AT cut in a surface mounting container (referred to as a surface mounting container) 1. The surface mounting container 1 is made of a laminated ceramic having a concave portion, and has mounting electrodes 4 (ab) and 5 (ab) which are pairs of crystal pieces 2 and 3 on the bottom and side surfaces of the four corners. Then, a step portion is provided in the concave portion of the surface mount container 1, and a metal ring 7 is attached to the opening surface, for example, and a metal cover 7 is joined by seam welding.
[0004]
The tuning fork type crystal piece 2 is made up of a tuning fork base 8 and a pair of tuning fork arms 9 (ab) by cutting, for example, X. Each of the four surfaces of the tuning fork arm 9 (ab) has excitation electrodes 10 that are electrically paired, and each extraction electrode (external connection electrode) 11 (ab) extends to both ends of the tuning fork base 8. Then, both ends of the tuning fork base 8 where the extraction electrode 11 (ab) extends are fixed to a terminal electrode (not shown) formed on the bottom surface of the concave portion of the surface mounting container 1 by the conductive adhesive 12, Connect mechanically.
[0005]
The AT-cut quartz crystal piece 3 has a flat plate shape and has excitation electrodes 13 (ab) paired with both main surfaces, and extends extraction electrodes 14 (ab) on both sides of one end. Then, both ends of the extended end portion of the extraction electrode 14 (ab) are fixed to the stepped portion where the terminal electrode (not shown) is formed by the conductive adhesive 12 as described above, and are electrically and mechanically connected. In short, the tuning fork type and the plate surfaces of the AT-cut crystal pieces 2 and 3 are arranged in the vertical direction.
[0006]
The terminal electrodes connected to the tuning fork type and AT cut crystal pieces 2 and 3 are connected to the mounting electrodes 4 (ab) and 5 (ab) through the laminated surface and electrode through holes (so-called through holes, not shown). .
[0007]
In such a case, for example, mounting electrodes 4 (ab) and 5 (ab) as tuning fork type and AT cut crystal resonators are connected to respective oscillation circuits provided on a set substrate constituting a mobile phone (not shown). To do. The AT cut oscillates in, for example, the MHz band, and the tuning fork type oscillates in the KHz band. The former functions as a communication frequency and the latter functions as a clock signal. Therefore, the tuning fork type and AT cut crystal pieces 2 and 3 having different functions are accommodated in the same surface mount container 1 to form two types of crystal resonators (tuning fork type and AT cut ). It is possible to reduce the size of electronic devices including the above.
[0008]
[Problems to be solved by the invention]
(Problem of the prior art) However, the multi-function type crystal unit having the above-described configuration,
The tuning fork type and AT cut crystal pieces (quartz crystal units) 2 and 3 are simultaneously driven to obtain a communication frequency and a clock signal, thereby causing the following problems.
[0009]
That is, the tuning fork type and AT cut crystal pieces 2 and 3 are accommodated in the same container, and form an oscillation closed loop with each oscillation circuit. As a matter of course, each oscillation circuit is also applied to a circuit pattern including each crystal resonator (crystal pieces 2, 3) and mounting electrodes 4 (ab), 5 (ab) formed on the surface mounting container 1 connected thereto. High frequency current flows.
[0010]
For this reason, electromagnetic waves due to the respective high-frequency currents leak from the crystal pieces 2 and 3 and the circuit pattern and jump to the other party, causing mutual interference in the surface mount container 1 constituting the AT cut and the tuning fork type crystal resonator, and oscillating. There was a problem that made it unstable. For example, there is a problem that a phase signal at f0 ± 32 KHz is increased by superimposing a clock signal (for example, 32 kHz) by a tuning fork type crystal resonator on a communication frequency f0 (for example, 12 MHz) by an AT cut crystal resonator. .
[0011]
In these cases, there is a problem of mutual interference between the excitation electrodes 10 and 13 of the crystal pieces 2 and 3 having a large area, and then between the mounting electrodes 4 and 5. Furthermore, this effect becomes more significant as the height and flat area become smaller and miniaturization progresses.
[0012]
(Object of the Invention) An object of the present invention is to provide a multi-frequency accommodation type crystal resonator which prevents mutual interference and ensures oscillation.
[0013]
[Means for Solving the Problems]
In the present invention, as shown in the claims (Claim 1), two crystal pieces of AT cut and tuning fork type are placed in the same container composed of a container body having a recess for surface mounting and a cover. In the sealed multi-frequency accommodation type crystal resonator, each of the crystal pieces is partitioned by a metal body to electrically shield each crystal piece, and at the four corners of the outer bottom surface of the container body, There are two mounting electrodes each electrically connected to one crystal piece, and a ground electrically connected to the metal body is provided between the mounting electrodes of the two crystal pieces on the outer bottom surface of the container body. A structure having electrodes.
[0014]
[Action]
In the present invention, since each crystal piece is shielded by the metal body, mutual interference of the oscillation circuits in the surface mount container 1 is prevented. Examples of the present invention will be described below.
[0015]
[First embodiment]
FIG. 1 (ab) is a diagram of a multi-frequency type crystal resonator for explaining the first embodiment of the present invention. FIG. 1 (a) is a sectional view and FIG. 1 (b) is a bottom view. In addition, the same number is attached | subjected to the same part as a prior art example, and the description is simplified or abbreviate | omitted.
As described above, the quartz resonator has the tuning fork type crystal piece 2 fixed to the bottom surface of the container body 1 having the concave portion made of laminated ceramic and the both ends of the AT cut crystal piece 3 fixed to the stepped portion with a conductive adhesive. The mounting electrodes 4 (ab) and 5 (ab) are extended on the bottom and side surfaces of the outer surface.
[0016]
In this embodiment, a step portion is further provided in the concave portion of the container body to form two steps, and a metal plate (metal body) 15 is provided in the first step, and the tuning fork type crystal piece 2 and the AT cut crystal piece 3 are particularly excited. The electrode is electrically shielded (shielded). The AT-cut crystal piece 3 is held at the second stage on both sides of one end. A cross-shaped ground electrode 16 that electrically shields between the mounting electrodes 4 (ab) and 5 (ab) is formed on the bottom surface of the container body, and is connected to the metal plate 15 through a through hole or the like (not shown). The metal ring 6 even after the conductor provided in the same manner as in the side wall of the container body 1 A - a source electrode 16 are electrically connected, so to speak, a shield container.
[0017]
With such a configuration, especially between the tuning fork type and the excitation electrodes of the AT-cut crystal pieces 2 and 3 are electrically shielded by the metal plate 15, it is possible to prevent the electromagnetic wave from jumping in due to the high-frequency current between them. Further, in this example, the mounting electrodes 4 (ab) and 5 (ab) are also electrically shielded by the ground electrode 16 to prevent the electromagnetic waves from entering here.
[0018]
Therefore, in each oscillation closed loop, the mutual interference in the surface mount container 1 constituting the AT cut and the tuning fork type crystal resonator is prevented, and the phase noise caused by the clock signal especially at the communication frequency is reduced. Maintain good oscillation.
[0019]
[Second embodiment]
FIG. 2 (ab) is a view of a crystal resonator for explaining a second embodiment of the present invention. FIG. 2 (a) is a sectional view and FIG. 2 (b) is a bottom view. The description of the same parts as those in the previous first embodiment is omitted or simplified.
In the first embodiment, the tuning fork type and the AT-cut crystal pieces 2 and 3 are accommodated in the concave portion provided on one main surface of the surface mount container 1, and the plate surfaces of the crystal pieces 2 and 3 are overlapped in the vertical direction. Although arranged, the second embodiment is an example in the case where the concave portions are provided on both main surface sides of the surface mount container 1 and the crystal pieces 2 and 3 are arranged in the vertical direction.
[0020]
That is, in 2nd Example, the container main body 1 which has a recessed part in both the main surface sides is formed from a laminated ceramic, and cross-sectional shape is made into H shape in general. A metal film made of metallization is provided on the horizontal portion that divides the H-shaped center to form a shield layer 21 as a metal body. A step portion extending over the entire circumference is provided in the concave portion on the other main surface side, and mounting electrodes 4 (ab) and 5 (ab) are formed in the four corner portions, and a ground electrode 16 is formed between the mounting electrodes. These are integrally formed when the ceramic is fired. And the metal ring 6 is joined on the surface of a step part using a silver solder or the like.
[0021]
Then, one end of the AT-cut crystal piece 3 with the lead electrode extended is provided on the bottom surface of the concave portion on one main surface side, and the both bottom ends of the base portion of the tuning-fork type crystal piece 2 are conductive on the bottom surface of the concave portion on the other main surface side. It adheres with the adhesive 12. The opening surface on the one main surface side is sealed by joining the metal cover 7 to the metal ring 6 by seam welding as described above. Further, the opening surface on the other main surface side is covered with a metal cover 7 on a metal ring 6 provided at the step portion and joined by beam welding. Any metal cover 7 and shield layer 21 are connected to the ground electrode.
[0022]
Even in such a configuration, as in the first embodiment, the shield layer 21 in the horizontal portion in which the space between the tuning fork type and the excitation electrodes of the AT cut crystal pieces 2 and 3 is H-shaped is electrically shielded. To do. Therefore, each oscillation is in a closed loop, and mutual interference in the surface mount container 1 constituting the AT cut and the tuning fork type crystal resonator is prevented and oscillation is maintained satisfactorily.
[0023]
In this example, since the ground electrode 16 connected to the metal cover 7 on the other main surface side is provided between the mounting electrodes 4 (ab) and 5 (ab), a shield electrode is formed as a whole, and the mounting electrode 4, The electrical coupling between the five is prevented to further prevent mutual interference. In addition, since the electrical coupling between the mounting electrodes 4 (ab) and 5 (ab) of the crystal pieces 2 and 3 is also prevented, the noise of each oscillator itself is also reduced. The same applies to the first embodiment.
[0024]
FIG. 3 (abc) is a view of a crystal resonator for explaining a third embodiment of the present invention. FIG. 3 (a) is a sectional view, FIG. 3 (b) is a plan view, and FIG. 3 (c) is a bottom view. It is. The description of the same parts as those in the previous embodiment is omitted or simplified.
In the first and second embodiments, the plate surfaces of the tuning fork type and AT-cut crystal pieces 2 and 3 are arranged in the container body 1 in the vertical direction. In the third embodiment, the plate surfaces of the crystal pieces 2 and 3 are arranged. It is an example at the time of arrange | positioning horizontally.
[0025]
That is, in the third embodiment, the central region of the container body 1 made of laminated ceramic is partitioned by the projecting portions 17, and the first and second storage portions 19 and 20 are provided on both sides. A metal film by metallization is formed on the outer surface of the protruding portion 17 to form a shield layer 21 as a metal body. The shield layer 21 is as close as possible to the metal cover 7. For example, a part may be spot welded. The first housing portion 19 is electrically conductive at both ends of the tuning fork base portion where the lead electrode of the tuning fork crystal piece 2 extends, and the second housing portion is electrically conductive at both ends of the same end portion of the AT-cut crystal piece 3. It is fixed by the adhesive 12.
[0026]
The opening surface of the container body 1 is sealed by joining the metal cover 7 to the metal ring 6 by seam welding as described above. Further, on the bottom surface of the container main body 1, mounting electrodes 4 (ab) and 5 (ab) connected to the excitation electrodes of the tuning fork type and AT cut crystal pieces 2 and 3 are extended, and these are shielded so The above-described ground electrode 16 connected to the shield layer 21 is formed.
[0027]
Even in such a configuration, the mounting electrode 4 (ab), between the excitation fork of the tuning fork type and the AT-cut quartz crystal pieces 2 and 3 by the shield layer 21 of the projecting portion 17, as in the first embodiment. 5 (ab) is electrically shielded by the ground electrode 16. Therefore, each oscillation is in a closed loop, and mutual interference in the surface mount container 1 constituting the AT cut and the tuning fork type crystal resonator is prevented and oscillation is maintained satisfactorily.
[0028]
[Other matters]
In each of the above embodiments, the tuning fork type and AT cut crystal pieces 2 and 3 are accommodated in the surface mount container 1 and connected to an external oscillation circuit in any of the embodiments. As shown in FIG. 4 (abc), the IC chip 22 “the same figure (a)” in which a step portion is further provided in the surface mount container 1 to integrate each oscillation circuit, or each IC chip 22 “the same figure. (Bc) "may be accommodated on the bottom surface to form an oscillator. However, in this case, the mounting electrode 23 serves as a power source, an earth, and an output terminal as an oscillator.
In other words, both sides of the same end portion of the AT-cut crystal piece 3 are fixed by the conductive adhesive 12.
[0029]
Further, as shown in FIG. 5 (ab), the container body 1 is generally H-shaped, and the concave portion on one main surface side accommodates the tuning fork type and AT cut crystal pieces 2 and 3, and the concave portion on the other main surface side. May include an IC chip 22 in which the oscillation circuits for the respective vibrators are individually integrated, or all of them are integrated, and either one is integrated. Even when such an oscillator is used, it belongs to the technical scope of the present invention.
[0030]
In addition, a metal ring 6 is provided on the opening surface of the container body 1 and a metal cover 7 is joined and sealed by seam welding. For example, by beam welding or sealing with glass or resin without providing the metal ring 6. There may be. However, seam and beam welding are suitable in terms of forming a shield container. In place of the metal ring 6, a metal film may be used. In short, it is sufficient that seam or beam welding can be performed.
[0031]
In addition, the crystal piece is a multi-function multi-frequency accommodation type crystal unit that obtains a clock signal and a communication frequency by accommodating different types as a tuning fork type and an AT cut. Both functional types and AT cuts may be used for communication frequencies or for clock signals between tuning forks, and can be applied to multi-frequency type crystal resonators having different oscillation frequencies. However, a multi-frequency type that is a multi-function type that obtains a clock signal and a communication frequency is practical.
[0032]
【The invention's effect】
The present invention provides a multi-frequency accommodation type crystal resonator in which two AT-cut and tuning-fork type crystal pieces are sealed in the same container comprising a container body having a recess for surface mounting and a cover. Each of the pieces is partitioned by a metal body to electrically shield each crystal piece, and at each of the four corners of the outer bottom surface of the container body, two pieces each electrically connected to the two crystal pieces are provided. A mounting electrode is provided, and a ground electrode electrically connected to the metal body is provided between the mounting electrodes of the two crystal pieces on the outer bottom surface of the container body. Therefore, it is possible to provide a multi-frequency accommodation type crystal resonator that can prevent the mutual interference of each crystal piece (AT cut and tuning fork type) and ensure oscillation.
[Brief description of the drawings]
1A and 1B are views for explaining a first embodiment of the present invention, in which FIG. 1A is a cross-sectional view of a crystal resonator, and FIG. 1B is a bottom view thereof;
2A and 2B are diagrams for explaining a second embodiment of the present invention, in which FIG. 2A is a cross-sectional view of a crystal resonator, and FIG. 2B is a bottom view of the same.
FIGS. 3A and 3B are views for explaining a third embodiment of the present invention, in which FIG. 3A is a cross-sectional view of a crystal unit, FIG. 3B is a plan view excluding a cover and a metal ring, and FIG. ) Is a bottom view of the same.
FIG. 4 is a diagram for explaining another embodiment of the present invention, and FIG. 4B is a cross-sectional view of an oscillator to which the present invention is applied.
FIG. 5 is a diagram for explaining still another embodiment of the present invention, and FIG. 5 (ab) is a cross-sectional view of an oscillator to which the present invention is applied.
FIG. 6 is a cross-sectional view of a crystal resonator for explaining a conventional example.
FIG. 7 is a bottom view of a crystal resonator for explaining a conventional example.
8A and 8B are diagrams for explaining a conventional example, in which FIG. 8A is a plan view of a tuning fork crystal piece, and FIG. 8B is a plan view of an AT cut.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Container body, 2 Tuning fork type crystal piece, 3 AT cut crystal piece, 4, 5, 23 Mounting electrode, 6 Metal ring, 7 Metal cover, 8 Tuning fork base, 9 Tuning fork arm, 10, 13 Excitation electrode, 11, 14 Lead electrode, 12 a conductive adhesive, 15 a metal plate, 16 A - scan electrode, 17 protrusion, 19, 20 storage portion, 21 the shield layer, 22 IC chip.

Claims (3)

In a multi-frequency accommodation type crystal resonator in which two crystal pieces of AT cut and tuning fork type are sealed in the same container consisting of a container body having a concave portion for surface mounting and a cover, each of the crystal pieces is electrically shielded to Rutotomoni between each crystal piece I partition a metal body, mounting electrodes one by each two in four corners of the outer bottom surface of the container body which is electrically connected to the two crystal element And a ground electrode electrically connected to the metal body between the mounting electrodes of the two crystal pieces on the outer bottom surface of the container main body . " The multi-frequency accommodating crystal resonator according to claim 1, wherein the crystal pieces are arranged in a vertical direction with plate surfaces overlapped in the same container. The multi-frequency accommodation type crystal resonator according to claim 1, wherein the crystal pieces are arranged in a horizontal direction with plate surfaces arranged in the same container.

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