JP4609196B2 - Piezoelectric vibrating piece, piezoelectric device, electronic apparatus and mobile phone device - Google Patents

Description

  The present invention relates to a piezoelectric vibrating piece, a piezoelectric device in which a piezoelectric vibrating piece is accommodated in a package or a case, and a mobile phone device and an electronic apparatus using the piezoelectric device.

Piezoelectric vibrators and piezoelectrics in small information devices such as HDDs (hard disk drives), mobile computers, IC cards, mobile communication devices such as mobile phones, car phones, and paging systems, and piezoelectric gyro sensors Piezoelectric devices such as oscillators are widely used.
FIG. 18 is a schematic plan view showing an example of a piezoelectric vibrating piece conventionally used in a piezoelectric device, and FIG. 19 is an end view taken along line AA in FIG.
In the figure, a piezoelectric vibrating reed 1 is formed by etching a piezoelectric material such as quartz to form an outer shape as a tuning fork type piezoelectric vibrating reed as shown in the figure, and is a rectangular shape attached to a package (not shown) or the like. A base 2 and a pair of vibrating arms 3 and 4 extending rightward from the base 2 in the drawing are provided, and long grooves 3a and 4a are formed on the main surfaces (front and back surfaces) of these vibrating arms, and necessary driving is performed. Electrode is formed (see Patent Document 1).

In such a piezoelectric vibrating piece 1, lead electrodes 5 and 6 provided at both ends in the width direction of the base 2 are provided on an electrode portion on a package (not shown) side that accommodates and fixes the piezoelectric vibrating piece 1. , 8 to be attached to the package.
In the piezoelectric vibrating reed 1, when a driving voltage is applied through the driving electrode routed around the extraction electrodes 5 and 6, the distal ends of the vibrating arms 3 and 4 are moved closer to and away from each other. In this manner, a signal having a predetermined frequency is extracted by bending vibration.

By the way, such a piezoelectric vibrating piece 1 is required to be formed in a small size in accordance with the downsizing of the various products to which the piezoelectric device using the piezoelectric vibrating piece 1 is attached. For this reason, the piezoelectric vibrating piece 1 must also be formed as small as possible, and in particular, it is required to reduce the total length AL1. Since downsizing of products is constantly progressing, the piezoelectric vibrating reed 1 has a structure that can be made smaller.
Here, the frequency f of the piezoelectric vibrating piece 1 which is a tuning-fork type piezoelectric vibrating piece as shown in the figure is W / (l × l), where l is the length of the vibrating arms 3 and 4 and W is the arm width. Proportional.
This means that when the piezoelectric resonator element 1 that is long in one direction is to be miniaturized and the total length AL1 in FIG. 18 is to be reduced, the frequency is increased if the length l of the vibrating arm is shortened. To do. Further, when the width W of the vibrating arm is decreased, the frequency is decreased. From this, in order to maintain the conventional frequency and reduce the size, it is necessary to reduce the arm width w while shortening the length of the vibrating arm to some extent.

JP 2002-261575 A

  By the way, in reducing the size of the piezoelectric vibrating reed 1, the length l of the vibrating arms 3 and 4 is shortened and the arm width W is reduced in order to maintain the conventional frequency, for example, 32 kHz (32.768 kHz). However, when processing the small piezoelectric vibrating piece 1, particularly when trying to reduce the arm width w while maintaining the characteristics, there are the following difficulties.

Specifically, it is necessary to process the long grooves 3a and 4a as shown in FIG. The dimension t in FIG. 19 is difficult to change because it is restricted by the conditions of the processing material such as a quartz wafer. Therefore, in the case where the conventional one is, for example, 100 μm, it is 100 μm even when the size is reduced.
On the other hand, the arm width W is assumed to be about 50 μm due to downsizing of the arm width W that has been 100 μm. When the arm width is 100 μm, the groove width C1 is about 70 μm and the side wall thicknesses S1 and S1 are about 15 μm, respectively. Must be about 5 μm each.

When such a piezoelectric vibrating piece is made, the rigidity of the vibrating arms 3 and 4 is greatly reduced, and the amplitude in the Z direction in FIG. The bending vibrations along the X direction of the arms 3 and 4 become bending vibrations as exaggerated by arrows SF and SF.
FIG. 20 is a graph showing drive characteristics when the piezoelectric vibrating piece is miniaturized with the conventional structure. When the drive voltage level is gradually increased along the horizontal axis of the figure, the frequency change on the vertical axis changes. It occurs in the negative direction. This indicates that the vibration in the Z direction in FIG. 19 increases, resulting in vibration with a large energy loss, which causes an increase in CI (crystal impedance) value.

  Further, as an effective measure for suppressing the CI value, there is a method in which the long grooves 3a and 4a described with reference to FIG. 18 are lengthened to increase the area for forming the driving electrode. However, the piezoelectric vibrating piece has a plurality of vibration modes, and the fundamental wave that is usually used is, for example, 32.768 kHz, whereas the second harmonic of the piezoelectric vibrating piece 1 is around 250 kHz. . The long grooves 3a and 4a can be lengthened to lower the CI value of the fundamental wave. However, since the CI value of the second harmonic is also lowered, as shown in FIG. 21, with many products, the CI value ratio that is the CI value of the harmonics / the CI value of the fundamental wave is maintained with the conventional structure. Is smaller than 1, and it is easy to oscillate with the second harmonic instead of the fundamental wave.

  The present invention has been made in order to solve the above-described problems. In order to reduce the size of a tuning fork-type vibrating piece, the CI value is suppressed and the vibration is suppressed by suppressing the movement of the vibrating arm in an unnecessary direction. It is an object of the present invention to provide a piezoelectric vibrating piece that does not deteriorate characteristics, a piezoelectric device using such a piezoelectric vibrating piece, a mobile phone device and an electronic apparatus using the piezoelectric device.

According to the first aspect of the present invention, in the first invention, the base portion formed of the piezoelectric material and the base portion are formed integrally with the base portion so as to intersect the electric axis direction (X-axis direction) of the piezoelectric material. A plurality of vibrating arms extending from one end, a long groove formed in each vibrating arm along the longitudinal direction of the vibrating arm, a driving electrode formed in the long groove, and a predetermined distance from the one end of the base A support arm that extends in the width direction of the piezoelectric vibrating piece from the joint portion with the base portion and extends along the longitudinal direction outside the vibrating arm, and each vibrating arm includes: The width portion at the position of the change point P has a reduced width portion whose width is gradually reduced from the base side toward the distal end side of the resonating arm, with the front end of the reduced width portion as the change point P. Width dimension is equal and constant compared to dimension Or extending from the change point P toward the tip side, and the long groove has a tip portion on the tip side of the vibrating arm, and the change point P is more than the tip portion of the long groove. Furthermore, it is located on the tip side of the vibrating arm, and the side surface of each vibrating arm is achieved by a piezoelectric vibrating piece in which a deformed portion protruding in the plus X-axis direction is formed within 5 μm.

According to the configuration of the first invention, when a driving electrode (excitation electrode) is formed in the long groove formed in the vibrating arm, the arm width is gradually reduced from the base side toward the tip side. By providing a width change change point P at which the width dimension is increased on the tip side, the oscillation at the second harmonic can be prevented while suppressing the CI value. In this case, assuming that the length and width of the vibrating arm are not uniform, depending on the piezoelectric vibrating piece, the change point P may be further set on the tip side of the vibrating arm than the tip of the long groove. By positioning it in the position, it is possible to provide a piezoelectric vibrating piece that suppresses the CI value and does not deteriorate the vibration characteristics.
When the outer shape of the piezoelectric vibrating piece is formed by wet etching, the deformed portion generated by the etching anisotropy is formed to be within 5 μm, so that the bending vibration of the vibrating arm is stabilized. it can.
According to a second aspect of the present invention, a base portion formed of a piezoelectric material and a plurality of vibrating arms formed integrally with the base portion and extending from one end of the base portion so as to intersect an electric axis direction (X-axis direction) of the piezoelectric material A long groove formed in each of the vibrating arms along the longitudinal direction of the vibrating arm, a driving electrode formed in the long groove, and the base that is a predetermined distance away from the one end of the base. A supporting arm that extends in the width direction of the piezoelectric vibrating piece from the joint and extends along the longitudinal direction outside the vibrating arm, and each vibrating arm includes the vibration from the base side. While having a reduced width portion where the width dimension gradually decreases toward the distal end side of the arm, the width dimension is compared with the width dimension at the position of the changed point P, with the leading end of the reduced width portion as the changed point P. Before is equally constant or increasing The long groove extends from the change point P toward the tip side, and the long groove has a tip portion on the tip side of the vibrating arm, and the change point P is further further than the tip portion of the long groove. Located on the distal end side, the base portion has a cut portion formed by reducing the width of the piezoelectric material in the width direction, and the cut portion has a width of the vibrating arm from the root of each vibrating arm. It is characterized in that it is formed in the base part at a distance of 1.2 times or more of the dimension.
According to the configuration of the second aspect of the present invention, in view of the fact that the range in which vibration leakage is transmitted when the vibrating arm of the tuning fork-type vibrating piece is flexibly vibrated is correlated with the arm width dimension of the vibrating arm. Have the knowledge that the cut portion of the conventional piezoelectric vibrating piece is not provided at an appropriate position.
Therefore, the position where the cut portion is provided is a position exceeding the arm width dimension of the vibrating arm from the base of the vibrating arm. Thereby, the notch part can be made into the structure which can suppress more reliably that the vibration leakage from a vibrating arm propagates to the base side. As a result, it is possible to appropriately prevent leakage of vibration from the vibrating arm side to the base side and to provide a piezoelectric vibrating piece with good drive level characteristics.
In particular, the drive level characteristic can be adapted to the level of a normal piezoelectric vibrating piece by forming the cut portion at a position away from the base portion by the arm width dimension × 1.2 or more. It has been confirmed.

According to a third invention, in the configuration of the first invention or the second invention, the width dimension of each of the vibrating arms is reduced in width toward the distal end side at a base portion of the vibrating arm with respect to the base portion. And a second reduced width portion that is gradually reduced from the end of the first reduced width portion as the reduced width portion toward the distal end side more gradually than the first reduced width portion. It is characterized by having.
According to the configuration of the third invention, the second reduced width portion in which the arm width of the vibrating arm is gradually reduced from the end of the first reduced width portion toward the distal end side. In addition, by providing a change point P of the width change in which the width dimension is increased on the tip side, it is possible to prevent oscillation at the second harmonic while suppressing the CI value.
In addition, since the first arm has a first width-decreasing portion that sharply contracts toward the distal end at the base of the base of the vibrating arm, the largest stress is applied when the vibrating arm is flexibly vibrated. The rigidity of the base portion that acts and increases the strain can be improved. This stabilizes the flexural vibration of the vibrating arm and suppresses vibration components in unnecessary directions, so that the CI value can be further reduced. That is, when the piezoelectric vibrating piece is downsized, stable bending vibration can be realized and the CI value can be kept low.

According to a fourth invention, in the configuration of the first invention, the base portion has a cut portion formed by reducing the width of the piezoelectric material in the width direction, and the cut portion is formed on each of the vibrating arms. It is characterized in that the base is formed at a distance of 1.2 times or more the width of the vibrating arm from the base.
According to the configuration of the fourth aspect of the present invention, in view of the fact that, when the vibrating arm of the tuning fork type vibrating piece undergoes flexural vibration, the range in which the vibration leakage is transmitted has a correlation with the arm width dimension of the vibrating arm. Have the knowledge that the cut portion of the conventional piezoelectric vibrating piece is not provided at an appropriate position.
Therefore, the position where the cut portion is provided is a position exceeding the arm width dimension of the vibrating arm from the base of the vibrating arm. Thereby, the notch part can be made into the structure which can suppress more reliably that the vibration leakage from a vibrating arm propagates to the base side. As a result, it is possible to appropriately prevent leakage of vibration from the vibrating arm side to the base side and to provide a piezoelectric vibrating piece with good drive level characteristics.
In particular, the drive level characteristic can be adapted to the level of a normal piezoelectric vibrating piece by forming the cut portion at a position away from the base portion by the arm width dimension × 1.2 or more. It has been confirmed.

According to a fifth aspect of the present invention, in the configuration according to any one of the first to fourth aspects, the ratio of the length of the long groove to the arm length of the vibrating arm is 61.5%, and the width of the vibrating arm is reduced. The maximum width / minimum width as the width ratio is set to 1.06 or more.
According to the fifth aspect of the invention, when N is 61 percent, for example, by setting M to 1.06 or more, the CI value of the fundamental wave is sufficiently suppressed, and at the same time secondary Thus, it is possible to obtain a piezoelectric vibrating piece that hardly oscillates at higher harmonics.

According to a sixth aspect of the invention, according to the configuration of the third aspect of the invention, the width of the first reduced width portion is 11 μm or more.
According to the configuration of the sixth aspect of the invention, the CI value can be significantly reduced by setting the width of the first reduced width portion to 11 μm or more.

The seventh invention is characterized in that the cut portion is located closer to the vibrating arm than the joint portion.
According to the structure of 7th invention, it can suppress that the vibration leak by the bending vibration of a vibration arm reaches the junction location of a support arm via the said base, and can prevent a raise of CI value.

The eighth invention is characterized in that the length of the support arm is set such that the tip of the support arm is closer to the base than the tip of the vibrating arm.
According to the configuration of the ninth aspect of the invention, in addition to the support arm extending in the same direction as the vibrating arm, the tip of the supporting arm is closer to the base than the tip of the vibrating arm. Thus, the whole can be reduced in size.

According to a ninth aspect of the invention, a part of the support arm is joined to the base, and a part between the part joined to the base and the joint to the base is a part of the part. The structure is characterized in that the rigidity is lower than that of the supporting arm portions located on both sides.
According to the ninth aspect of the invention, even if a slight amount of vibration leakage due to flexural vibration of the vibrating arm reaches the supporting arm, it can be reduced as much as possible.

A tenth aspect of the invention is characterized in that the thickness of the part of the support arm with the reduced rigidity is thinner than the part of the support arm located on both sides thereof.
According to the configuration of the tenth invention, when the structure with reduced rigidity is a reduced width portion formed in the middle of the supporting arm, such a structure is easily formed when the outer shape of the piezoelectric vibrating piece is formed. be able to.

An eleventh invention is a piezoelectric device characterized in that the piezoelectric vibrating piece is accommodated in a package or a case.
According to the configuration of the eleventh aspect of the invention, it is possible to realize a small and compact piezoelectric device that is strong against impact, suppresses the CI value, does not deteriorate the vibration characteristics, and improves the temperature characteristics.

Further, the above object is a mobile phone device using a piezoelectric device in which a piezoelectric vibrating piece is accommodated in a package or case, wherein the piezoelectric vibrating piece is integrally formed with a base portion made of a piezoelectric material. A plurality of vibrating arms formed and extending from one end of the base so as to intersect the electric axis direction (X-axis direction) of the piezoelectric material, and long grooves formed in the vibrating arms along the longitudinal direction of the vibrating arms And extending in the width direction of the piezoelectric vibrating piece from a joint portion between the driving electrode formed in the long groove and the base portion that is a predetermined distance away from the one end of the base portion, and outside the vibrating arm. A supporting arm extending along the longitudinal direction, and each of the vibrating arms has a reduced width portion whose width is gradually reduced from the base side toward the distal end side of the vibrating arm. With The tip of the reduced width portion is defined as a change point P, and extends from the change point P toward the tip side so that the width dimension is equal or constant or increased as compared with the width dimension at the position of the change point P. The long groove has a tip on the tip side of the vibrating arm, the change point P is located further on the tip side of the vibrating arm than the tip of the long groove, and the side surface of each vibrating arm is This is achieved by a cellular phone device that obtains a clock signal for control by the piezoelectric device having the piezoelectric vibrating piece in which the deformed portion protruding in the plus X-axis direction is formed within 5 μm.

According to a thirteenth aspect of the present invention, there is provided an electronic apparatus using a piezoelectric device in which a piezoelectric vibrating piece is accommodated in a package or case, wherein the piezoelectric vibrating piece is formed of a piezoelectric material. A base, a plurality of vibrating arms formed integrally with the base and extending from one end of the base so as to intersect an electric axis direction (X-axis direction) of the piezoelectric material, and the longitudinal direction of the vibrating arms Extending in the width direction of the piezoelectric vibrating piece from the joint between the long groove formed in each vibrating arm, the driving electrode formed in the long groove, and the base portion at a predetermined distance from the one end of the base portion. And a supporting arm extending along the longitudinal direction outside the vibrating arm, and each of the vibrating arms gradually has a width dimension from the base side toward the distal end side of the vibrating arm. Reduce to It has a width portion, and the tip of the reduced width portion is used as a change point P. From the change point P to the tip side so that the width dimension is equal or constant or increased compared to the width dimension at the position of the change point P. The long groove has a tip on the tip side of the vibrating arm, the change point P is located further on the tip side of the vibrating arm than the tip of the long groove, The side surface of the vibrating arm is achieved by an electronic device that obtains a clock signal for control by the piezoelectric device having the piezoelectric vibrating piece in which the deformed portion protruding in the plus X-axis direction is formed within 5 μm. .

1 to 4 show an embodiment of the piezoelectric device of the present invention, FIG. 1 is a schematic plan view thereof, FIG. 2 is a schematic sectional view taken along line BB of FIG. 1, and FIG. 3 is a piezoelectric device of FIG. 4 is a schematic plan view showing an embodiment of a piezoelectric vibrating piece used in FIG. 4, and FIG. 4 is an end view taken along the line CC of FIG.
As shown in FIGS. 1 and 2, the package 57 is formed in a rectangular box shape, for example. Specifically, the package 57 is formed by laminating a first substrate 54, a second substrate 55, and a third substrate 56. For example, as an insulating material, a ceramic green made of aluminum oxide is used. After the sheet is formed into the illustrated shape, it is sintered.
The bottom of the package 57 has a through hole 27 for degassing in the manufacturing process. The through hole 27 is formed in the first hole 25 formed in the first substrate 54 and the second substrate 55, has an outer diameter smaller than that of the first hole 25, and the first hole 25. The second hole 26 communicates with the second hole 26.
The through hole 27 is sealed with a sealing material 28 so that the inside of the package 57 is airtight.

As shown in FIG. 2, the package 57 forms a space of the internal space S by removing the material inside the third substrate 56. This internal space S is a housing space for housing the piezoelectric vibrating piece 32. Then, on the electrode portions 31 and 31 formed on the second substrate 55, the positions of the extraction electrodes 37 a and 38 a provided at the base portion of the piezoelectric vibrating piece 32 are placed via the conductive adhesives 43 and 43. Are joined together. The electrode portions 31 and 31 use mounting terminals 41 and 42 on the back surface of the package, conductive through holes (via holes), conductive patterns (not shown) drawn around the outer corners of the package 57, and the like. It is connected. The package 57 is hermetically sealed in a vacuum state by housing the piezoelectric vibrating piece 32 in a vacuum state using a vacuum chamber or the like and then bonding a transparent glass lid 40 using a sealing material 38. Is sealed. Thus, after sealing the lid 40, the laser beam LB is irradiated from the outside to trim the electrode of the piezoelectric vibrating piece 32 and adjust the frequency.
The lid 40 may be a metal plate such as Kovar. In this case, the frequency of the piezoelectric vibrating piece 32 cannot be adjusted by irradiating the laser beam LB from the outside.

The piezoelectric vibrating piece 32 is formed of, for example, quartz, and a piezoelectric material such as lithium tantalate or lithium niobate can be used in addition to quartz. As shown in FIG. 3, the piezoelectric vibrating piece 32 includes a base 51 fixed to the package 57 side, and a pair of vibrations extending in parallel with the base 51 as a base end in a bifurcated manner toward the top in the figure. Arms 35 and 36 are provided.
Long grooves 33 and 34 extending in the length direction are preferably formed on the front and back of the main surfaces of the vibrating arms 35 and 36, respectively. As shown in FIGS. 3 and 4, driving electrodes are formed in the long grooves. Excitation electrodes 37 and 38 are provided. The tuning fork-shaped outer shape of the piezoelectric vibrating piece 32 and the long groove provided in each vibrating arm should be precisely formed by wet etching a material such as a quartz wafer with a hydrofluoric acid solution or dry etching, for example. Can do.

The excitation electrodes 37 and 38 are formed in the long grooves 33 and 34 and on the side surfaces of the vibrating arms, and the electrodes in the long grooves and the electrodes provided on the side surfaces of each vibrating arm are paired. The excitation electrodes 37 and 38 are respectively routed to the extraction electrodes 37a and 38a described in FIG. As a result, when the piezoelectric device 30 is mounted on a mounting substrate or the like, an external driving voltage is applied from the mounting terminals 41 and 42 to the lead electrodes 37a and 38a of the piezoelectric vibrating piece 32 via the electrode portions 31 and 31, respectively. , And further to each excitation electrode 37, 38.
Then, by applying a driving voltage to the excitation electrodes in the long grooves 33 and 34, the electric field efficiency inside the region where the long grooves of the respective vibrating arms are formed can be increased during driving.

That is, as shown in FIG. 4, the excitation electrodes 37 and 38 are connected to an AC power supply by cross wiring so that an alternating voltage as a drive voltage is applied to the vibrating arms 35 and 36 from the power supply. It has become.
As a result, the vibrating arms 35 and 36 are excited so as to have opposite-phase vibrations, and in the fundamental mode, that is, in the fundamental wave, the vibrating arms 35 and 36 are flexibly vibrated so that the distal end sides of the vibrating arms 35 and 36 are moved closer to and away from each other. It is like that.
Here, for example, the fundamental wave of the piezoelectric vibrating piece 32 has a Q value of 12000, a capacitance ratio (C0 / C1): 260, a CI value of 57 kΩ, and a frequency of 32.768 kHz (“kilohertz”, the same applies hereinafter).
The second-order harmonics are, for example, Q value: 28000, capacity ratio (C0 / C1): 5100, CI value: 77 kΩ, and frequency: 207 kHz.

  Further, preferably, in the base portion 51, as in the vibrating piece of FIG. 18, recesses or notches 71 and 71 formed on the both side edges of the base portion 51 by partially reducing the width in the width direction of the base portion 51. Is provided. The position of the cut portion will be described later. By forming the notches 71 and 71 in the base 51, it is possible to greatly reduce the leakage of vibration to the base 51 due to the bending vibrations of the vibrating arms 35 and 36, and to obtain the effect of suppressing the CI value. it can.

  Further, in the piezoelectric vibrating piece 32, the vibrating arms 35 and 36 are formed to have a shape as shown in FIG. Since each vibrating arm has the same shape, the vibrating arm 36 will be described. At the base end T extending from the base 51, the width of the vibrating arm is the widest. Then, a first reduced width portion TL that is suddenly reduced in width is formed between U positions that are separated from the position of T, which is the root of the vibrating arm 36, by a slight distance toward the distal end side of the vibrating arm 36. Yes. Then, from the position of U, which is the end of the first reduced width portion TL, to the position of P toward the distal end side of the vibrating arm 36 further, that is, with respect to the vibrating arm, the reduced width gradually and continuously over the distance of CL. A second reduced width portion is formed. It should be noted that from the position P in FIG. 3 to the distal end side of the vibrating arm, it may be gradually widened as shown, or the arm width may be hardly changed. Then, when the arm width on the tip side from the position of P is not changed, the electrode film (metal coating) in the region may be thickened in the electrode forming step described later to increase the weight.

The vibration arm 36 is provided with high rigidity in the vicinity of the base close to the base by providing the first reduced width portion TL. Further, since the second reduced width portion is formed from the end U of the first reduced width portion toward the tip, the rigidity is continuously reduced. A portion P is a change point P of the arm width, and in the form of the vibrating arm 36, it is a partially constricted position, and can be expressed as a constricted position P. In the vibrating arm 36, the tip end side further from the constriction position P has the arm width extended with the same dimension as described above, or gradually expanded as shown.
Here, as the long grooves 33 and 34 in FIG. 3 are longer, the electric field efficiency of the material forming the vibrating arms 35 and 36 is improved, and the length of the long grooves 33 and 34 from the base 51 with respect to the entire length L of the vibrating arms. It is known that the CI value of the tuning fork type resonator element decreases as PL becomes longer at least up to about PL / L = 0.7. In this embodiment, in FIG. 3, the total length L of the vibrating arm 36 is, for example, about 1250 μm.

Assuming the above structure, in this embodiment, in FIG. 3, the total length L of the vibrating arm 36 is, for example, about 1250 μm, and the following relationship is established.
In FIG. 5, when the constriction position P that is the arm width change point P is taken on the horizontal axis, depending on where the constriction position P is in the length direction of the vibrating arm (horizontal axis), The vertical axis shows how the CI value of the piezoelectric vibrating piece 32 changes. The percentage on the horizontal axis of the graph of FIG. 5 indicates the ratio of the length CL from the base to the constriction position P when the total length L of the vibrating arm is “1”. The position of “0” on the horizontal axis is the tip position of the long groove 34 indicated by the length PL in FIG. 3, and the position of “0” is a constricted position (change point) at the tip position of the long groove 34. It shows that there is P.
Referring to FIG. 5, the length PL of the long groove is set to an appropriate length as described above, and the CI value is sufficiently suppressed. At the same time, the constriction position P with respect to the tip position of the long groove. It can be seen that the CI value varies greatly depending on whether or not the above is provided. In addition, the CI value can be drastically reduced by providing the constriction position (arm width change point) P further on the tip side of the vibrating arm than the tip of the long groove.

The horizontal axis in FIG. 6 indicates at which position in the length direction of the vibrating arm the constriction position P is present, and the vertical axis indicates the CI value ratio of the piezoelectric vibrating piece 32 corresponding to the position. The change in (CI value of harmonics / CI value of fundamental wave) is shown. The horizontal axis of the graph of FIG. 6 is the same as that of FIG. When the CI value ratio is smaller than 1, the CI value of the fundamental wave becomes larger than the CI value of the harmonic wave, and oscillation is easily caused by the harmonic wave.
Referring to FIG. 6, if the length PL of the long groove is set to an appropriate length as described above and the CI value is sufficiently suppressed, the CI value of the piezoelectric vibrating piece 32 even if the constriction position P is displaced to some extent. The ratio (CI value of the harmonic / CI value of the fundamental wave) can be maintained at a value greater than 1, and the CI value ratio increases as the constriction position P approaches the tip, and it is difficult for the harmonics to oscillate. It is shown.
Thus, with respect to the vibrating arm 36 of FIG. 3, the CI value decreases as the long groove 34 is lengthened.
By providing the constriction position (change point) P from the tip of the vibrating arm, it is possible to further increase the CI value ratio while reducing the CI value. For this reason, the constriction position P is preferably provided closer to the distal end side of the vibrating arm than the distal end portion of the long groove, so that the CI value ratio can be almost certainly increased and oscillation due to harmonics can be prevented.

Further, FIG. 7 shows an arm width reduction ratio M of the vibrating arm 36 when the ratio N of the groove length, which is the length PL of the long groove 34 / the length of the vibrating arm 36 in FIG. Is a graph in which the value of maximum width (W2) / minimum width (W1) of the vibrating arm is taken on the horizontal axis and the CI value ratio is taken on the vertical axis.
As shown in the figure, the larger the arm width reduction ratio M, the greater the CI value ratio, which is preferable. In this embodiment, by making the arm width reduction ratio M of the vibrating arm 36 larger than 1.06, the CI value ratio can be made larger than 1, and oscillation due to harmonics can be prevented.
Thus, in the piezoelectric vibrating piece 32, the value of the maximum width / minimum width = M as the width reduction ratio of the arm width of the vibrating arm is related to the ratio of the length of the long groove to the arm length of the vibrating arm = N. By determining the size, the piezoelectric vibration piece 32 and the piezoelectric device 30 on which the piezoelectric vibration piece 32 is mounted can be reduced in size, the CI value can be reduced, and it is difficult to oscillate with higher harmonics, thereby realizing good vibration characteristics.

FIG. 8 illustrates the relationship between the width dimension of the first reduced width portion TL shown on the right side of FIG. 3 and the CI value.
In this case, the height dimension TH of the first reduced width portion is about 50 μm, the width TW is taken on the horizontal axis, and the change in the CI value shown on the vertical axis is recorded.
As shown in the figure, when the TW is small, the CI value is high, and when the TW is large, the distortion is reduced, the vibration component in the Z direction described in FIG. 19 is reduced, and the vibration is stabilized. Get smaller. As shown in the figure, in this case, TW is 0, that is, the first reduced width portion is not formed at all, and the first reduced width portion is provided to form TW of about 10 μm, particularly around 11 μm. In this case, a significant decrease in CI value is observed. Further, the CI value gradually decreases while the dimension of the TW is increased to increase the base 51 to the full width.

As described above, according to the present embodiment, the rigidity of the root portions of the vibrating arms 35 and 36 of the piezoelectric vibrating piece 32, that is, the vicinity of the root is enhanced by the first reduced width portion. Thereby, the flexural vibration of the vibrating arm can be further stabilized and the CI value can be suppressed.
In addition, by providing the second reduced width portion, the vibration arm 36 gradually decreases in rigidity from the vicinity of the base toward the constriction position P toward the distal end side, and further from the constriction position P to the distal end side. Since there is no long groove 34 and the arm width is gradually enlarged, the rigidity is increased toward the tip side.
For this reason, it is considered that the “node” of vibration at the time of vibration in the second harmonic can be positioned on the more distal end side of the vibrating arm 36, which makes the long groove 34 longer and the piezoelectric material Even if the electric field efficiency is increased and the CI value is increased, the CI value of the second harmonic can be prevented from being lowered while the CI value of the fundamental wave is suppressed. Thus, even if the size is reduced, the CI value of the fundamental wave can be kept low, and a piezoelectric vibrating piece that does not deteriorate the drive characteristics can be provided.

Next, a preferable detailed structure of the piezoelectric vibrating piece 32 of the present embodiment will be described with reference to FIGS. 3 and 4.
Since the vibrating arms 35 and 36 of the piezoelectric vibrating piece 32 shown in FIG. 3 have the same shape, the matter that describes either the vibrating arm 35 or the vibrating arm 36 is common to both vibrating arms.
The wafer thickness indicated by the dimension x in FIG. 4, that is, the thickness of the crystal wafer forming the piezoelectric vibrating piece is preferably 70 μm to 130 μm.
The total length of the piezoelectric vibrating piece 32 indicated by the dimension a in FIG. 3 is about 1300 μm to 1600 μm.
The dimension b which is the total length of the vibrating arm is 1100 to 1400 μm, and about 1250 μm is most preferable for the reason described above.
The total width d, which is the base width of the piezoelectric device 30, is preferably about 400 μm to 600 μm from the viewpoint of miniaturization of the piezoelectric device, and in this embodiment is about 500 μm. For this reason, in order to reduce the size of the tuning fork portion, the width dimension e on the tip side of the base 51 is about 200 to 400 μm.

Also, the dimension k between the vibrating arms 35 and 36 in FIG. 3 is preferably 50 to 100 μm. When the dimension k is less than 50 μm, when the outer shape of the piezoelectric vibrating piece 32 is formed by penetrating a quartz crystal wafer by wet etching, as will be described later, a deformed portion based on etching anisotropy, that is, a symbol in FIG. It is difficult to sufficiently reduce the fin-shaped convex portion in the plus X-axis direction on the side surface of the vibrating arm indicated by 81. If the dimension k is 100 μm or more, the flexural vibration of the vibrating arm may become unstable.
Furthermore, the dimensions m1 and m2 of the outer edge of the long groove 33 and the outer edge of the vibrating arm in the vibrating arm 35 (same as the vibrating arm 36) in FIG. 4 are preferably 3 to 15 μm. By setting the dimensions m1 and m2 to 15 μm or less, the electric field efficiency is improved, and by setting the dimensions m1 and m2 to 3 μm or more, it is advantageous for surely polarizing the electrodes.

In the vibrating arm 36 of FIG. 3, the position of the arm width change point P where the degree of widening that the tip side is wider than the arm width change point P is the position where the arm width of the vibrating arm 36 is minimized. It is preferable to increase the width by about 0 to 20 μm. If the width is increased beyond this, the tip of the vibrating arm 36 becomes too heavy, and the stability of bending vibration may be impaired.
Also, a deformed portion 81 that protrudes in a fin shape in the plus X-axis direction is formed on one side surface outside the vibrating arm 35 (same for the vibrating arm 36) in FIG. This is formed as an etching residue due to crystal etching anisotropy when wet-etching the piezoelectric vibrating piece, preferably in an etching solution with hydrofluoric acid and ammonium fluoride, It is preferable to obtain a stable bending vibration of the vibrating arm 35 by reducing the protrusion amount v of the deformed portion 81 within 5 μm by etching for 9 hours to 11 hours.

The width dimension of the long groove indicated by dimension g in FIG. 3 is preferably about 60 to 90 percent of the arm width c of the vibrating arm in the region where the long groove of the vibrating arm is formed. Since the first and second reduced width portions are formed in the vibrating arms 35 and 36, the arm width c varies depending on the position in the length direction of the vibrating arm, but the long groove is larger than the maximum width of the vibrating arm. The width g is about 60 to 90 percent. If the width of the long groove is smaller than this, the electric field efficiency is lowered and the CI value is increased.
Further, the total length h of the base 51 in FIG. 3 is conventionally about 30% with respect to the total length a of the piezoelectric vibrating piece 32, but this embodiment is about 15 to 25% due to the use of a cut portion or the like. It is possible to reduce the size.

  Further, in view of the fact that when the vibrating arms 35 and 36 of the piezoelectric vibrating piece 32 flexurally vibrate, the range in which the vibration leakage is transmitted has a correlation with the arm width dimension c of the vibrating arm. It was found that the cut portion of the piezoelectric vibrating piece was not provided at an appropriate position. Therefore, the position where the cut portion 71 in FIG. 3 is provided is a location having a dimension i exceeding the arm width dimension c of the vibrating arm from the base of the vibrating arm. Thereby, the notches 71 and 71 can have a structure that can more reliably suppress propagation of vibration leakage from the vibrating arms 35 and 36 to the base side. As a result, it is possible to appropriately prevent leakage of vibration from the vibrating arm side to the base side and to provide a piezoelectric vibrating piece with good drive level characteristics.

In particular, the cut portions 71 and 71 are formed away from the base T of the vibrating arms 35 and 36 by a dimension i of arm width dimension c × 1.2 or more, so that the drive level characteristic is normal piezoelectric vibrating piece 32. It has been confirmed that it can be adapted to different levels.
In addition, the position of the end portion on the base 51 side of the long grooves 33 and 34 is the same as the root of the vibrating arms 35 and 36, that is, the position of T in FIG. It is preferable to be within the range where the reduced width portion TL exists, and it is particularly preferable not to enter the base end side of the base portion 51 from the T position.

FIG. 9 is a circuit diagram illustrating an example of an oscillation circuit when a piezoelectric oscillator is configured using the piezoelectric vibrating piece 32 of the present embodiment.
The oscillation circuit 91 includes an amplification circuit 92 and a feedback circuit 93.
The amplifier circuit 92 includes an amplifier 95 and a feedback resistor 94. The feedback circuit 93 includes a drain resistor 96, capacitors 97 and 98, and the piezoelectric vibrating piece 32.
Here, the feedback resistor 94 in FIG. 9 can be about 10 MΩ (mega ohm), for example, and the amplifier 95 can be a CMOS inverter. The drain resistor 96 can be, for example, 200 to 900 kΩ (kiloohms), and the capacitor 97 (drain capacitance) and the capacitor 98 (gate capacitance) can be 10 to 22 pF (picofarad), respectively.

(Piezoelectric device manufacturing method)
Next, an example of the manufacturing method of all the embodiments of the present invention including the above-described piezoelectric device will be described with reference to the flowchart of FIG.
The piezoelectric vibrating piece 32, the package 57, and the lid body 40 of the piezoelectric device 30 are manufactured separately.
(Method for manufacturing lid and package)
The lid 40 is prepared, for example, as a lid having a size suitable for sealing the package 57 by cutting a glass plate (for example, borosilicate glass) having a predetermined size.
As described above, the package 57 is formed by laminating a plurality of substrates formed by molding an aluminum oxide ceramic green sheet and then sintering. At the time of molding, each of the plurality of substrates forms a predetermined hole on the inner side thereof, so that a predetermined internal space S is formed on the inner side when stacked.

(Method for manufacturing piezoelectric vibrating piece)
First, a piezoelectric substrate is prepared, and the outer shape of a predetermined number of piezoelectric vibrating pieces is simultaneously formed by etching from one piezoelectric substrate (outer shape etching).
Here, as the piezoelectric substrate, for example, a quartz wafer having a size capable of separating a plurality or a large number of the piezoelectric vibrating reeds 32 among the piezoelectric materials is used. Since this piezoelectric substrate forms the piezoelectric vibrating piece 32 of FIG. 3 as the process proceeds, a piezoelectric material, for example, such that the X axis shown in FIG. 3 is the electric axis, the Y axis is the mechanical axis, and the Z axis is the optical axis. It will be cut from a single crystal of quartz. In addition, when cutting from a single crystal of quartz, in the orthogonal coordinate system composed of the X-axis, Y-axis, and Z-axis described above, it rotates in the range of 0 to 5 degrees (θ in FIG. 11) clockwise around the Z-axis. Then, the crystal Z plate cut out is cut and polished to a predetermined thickness.

In the outer shape etching, the outer shape of the piezoelectric vibrating piece is etched using, for example, a hydrofluoric acid solution with respect to the piezoelectric substrate exposed as a portion outside the outer shape of the piezoelectric vibrating piece using a mask such as a corrosion-resistant film (not shown). . As the corrosion resistant film, for example, a metal film in which gold is vapor-deposited with chromium as a base can be used. This etching process is wet etching and changes depending on the concentration, type, temperature, and the like of the hydrofluoric acid solution.
Here, in the wet etching in the outer shape etching process, the following etching anisotropy is exhibited with respect to the electrical axis X, the mechanical axis Y, and the optical axis Z shown in FIG.
That is, with respect to the piezoelectric vibrating piece 32, the etching rate in the XY plane is in the plus X direction, and the etching progresses in the plane of 120 degrees with respect to the X axis and in the minus 120 degrees direction. The progress of etching on the inner surface in the direction of plus 30 degrees with respect to the X axis in the minus X direction and in the direction of minus 30 degrees is slow.
Similarly, the progress of etching in the Y direction is faster in the plus 30 degree direction and the minus 30 degree direction, and in the plus Y direction, the plus 120 degree direction and the minus 120 degree direction are delayed with respect to the Y axis.

Due to such anisotropy in etching progress, the piezoelectric vibrating piece 32 is formed with a deformed portion protruding in a fin shape on the outer side surface of each vibrating arm, as indicated by reference numeral 81 in FIG. .
However, in this embodiment, etching is performed using hydrofluoric acid and ammonium fluoride as an etchant for a sufficient time, that is, a sufficient time of 9 to 11 hours, so that in FIG. The described deformed portion 81 can be made extremely small (ST11).
In this process, the outer shape including the cut portions 71 and 71 of the piezoelectric vibrating piece 32 is formed, and at the end, the outer shape of a large number of piezoelectric vibrating pieces 32 connected to the quartz wafer near the base 51 by thin connecting portions. A finished product is obtained.

(Half etching process for groove formation)
Next, a groove forming resist (not shown) is used to form the shape shown in FIG. 4. Under the same etching conditions, the front and back surfaces of the vibrating arms 35 and 36 are respectively wet-etched to form bottom portions corresponding to the long grooves (ST12).
Here, referring to FIG. 4, the groove depth indicated by the symbol t is about 30 to 45 percent with respect to the total thickness x. If t is 30% or less of the total thickness x, the electric field efficiency may not be sufficiently improved. If it is 45% or more, the rigidity may be insufficient to adversely affect the bending vibration or the strength may be insufficient.

Note that one or both of the outer shape etching and the groove etching may be simultaneously performed by dry etching. In that case, for example, on the piezoelectric substrate (crystal wafer), the outer shape of the piezoelectric vibrating piece 32 and the region corresponding to the long groove after the outer shape is formed are covered with a metal mask each time. In this state, for example, it can be housed in a chamber (not shown), and an etching gas can be supplied at a predetermined degree of vacuum to generate etching plasma for dry etching. That is, for example, a freon gas cylinder and an oxygen gas cylinder are connected to a vacuum chamber (not shown), and further, an exhaust pipe is provided in the vacuum chamber so that it is evacuated to a predetermined degree of vacuum. Yes.
When a DC voltage is applied in a state where the inside of the vacuum chamber is evacuated to a predetermined degree of vacuum, a freon gas and an oxygen gas are sent, and the mixed gas is filled up to a predetermined atmospheric pressure, plasma is generated. appear. The mixed gas containing ionized particles hits the piezoelectric material exposed from the metal mask. Due to this impact, it is physically scraped off and scattered, and etching proceeds.

(Electrode formation process)
Next, a metal serving as an electrode, for example, gold is coated on the entire surface by vapor deposition or sputtering, and then a resist in which a portion where an electrode is not formed is exposed is exposed by a photolithography technique in FIGS. 1 and 4. The described driving electrode is formed (ST13).
Thereafter, weighting electrodes (metal coatings) 21 and 21 are formed on the tip portions of the vibrating arms 35 and 36 by sputtering or vapor deposition (see FIG. 3) (ST14). The weighting electrodes 21 and 21 are not energized and used for driving the piezoelectric vibrating piece 32 but are used for frequency adjustment described later.

Next, rough adjustment of the frequency is performed on the wafer (ST15). Coarse adjustment is frequency adjustment by a mass reduction method by partially evaporating part of the weighted electrodes 21 and 21 by irradiating an energy beam such as laser light.
Subsequently, the thin connecting portion with respect to the wafer is broken, and the piezoelectric vibrating reed 32 is individually formed (ST16).
Next, as described with reference to FIG. 1, conductive adhesives 43 and 43 are applied to the electrode portions 31 and 31 of the package 57, and portions of the extraction electrodes 37 a and 38 a of the base portion 51 of the piezoelectric vibrating piece 32 are formed thereon. The piezoelectric vibrating piece 32 is bonded to the package 57 by heating and curing the adhesive (ST17).
As the conductive adhesive 43, for example, a binder component using a synthetic resin or the like is mixed with conductive particles such as silver particles, which can perform mechanical joining and electrical connection at the same time. It is.

Subsequently, when the lid 40 is formed of an opaque material such as metal, the through hole 27 described in FIG. 2 is not provided. For this reason, for example, the laser beam is applied to the vibrating arm 35 and / or the vibrating arm of the piezoelectric vibrating piece 32 while applying a driving voltage to the piezoelectric vibrating piece 32 and observing the frequency before joining the lid body 40. Irradiate the tip side of the 36 weighted electrodes 21 and perform frequency adjustment as fine adjustment by the mass reduction method (ST18-1).
Next, the lid 40 is joined to the package 57 by seam welding or the like (ST19-1), and the piezoelectric device 30 is completed through necessary inspections.

Alternatively, when the package 57 is sealed with the transparent lid 40, the lid 40 is joined to the package 57 after the piezoelectric vibrating piece 32 is joined in ST17 (ST18-2).
In this case, for example, a heating step is performed in which the low melting point glass or the like is heated to join the lid 40 to the package 57. At this time, gas is generated from the low melting point glass or the conductive adhesive. Therefore, by heating, such a gas is discharged from the through hole 27 described with reference to FIG. 2 (degassing), and thereafter, metal spheres or pellets made of gold tin, more preferably gold germanium, etc. are arranged on the stepped portion 29. Then, it is melted by irradiating it with a laser beam or the like. Thereby, the metal filler 28 in FIG. 2 hermetically seals the through hole 27 (ST19-2).
Next, as shown in FIG. 2, the laser beam is externally applied to the vibrating arm 35 of the piezoelectric vibrating piece 32 and / or the weighting electrode 21 of the vibrating arm 36 so as to transmit the transparent lid 40 made of borosilicate glass or the like. The tip side is irradiated and frequency adjustment as fine adjustment is performed by the mass reduction method (ST20-2). Next, the piezoelectric device 30 is completed through necessary inspections.

(Second Embodiment)
12 and 13 show a second embodiment of the piezoelectric device of the present invention. FIG. 12 is a schematic plan view thereof, and FIG. 13 is an end view taken along the line DD of FIG.
In these drawings, the piezoelectric device 30-1 shows an example in which a piezoelectric vibrator is configured, and this piezoelectric device 30-1 houses a piezoelectric vibrating piece 32 in a package 57-1 which is a base. .
This package 57-1 has substantially the same structure as the package 57 of the first embodiment.
On each electrode part 31-1, 31-2, 31-1, 31-2 formed on the second substrate 55 of the package 57-1, conductive adhesives 43, 43, 43, 43 are used. The later-described extraction electrode forming portions of the supporting arms 61 and 62 of the piezoelectric vibrating piece 32-3 are placed and joined.
Therefore, after the piezoelectric vibrating piece 32-1 is fixed and supported by the conductive adhesive 43, the difference in linear expansion coefficient between the material constituting the piezoelectric vibrating piece 32-1 and the material constituting the package 57 is caused. As a result, residual stress exists in the base 51.

The piezoelectric vibrating piece 32-1 can be formed using a piezoelectric material as in the first embodiment. As shown in FIG. 1, the piezoelectric vibrating piece 32-1 includes a base 51 and a pair of vibrating arms 35 that extend in parallel from the one end (right end in the drawing) to the right. , 36 are provided.
Long grooves 33 and 34 extending in the length direction are preferably formed on the front and back surfaces of the main surfaces of the vibrating arms 35 and 36, respectively, and the drive in the long grooves is the same as described with reference to FIGS. Excitation electrodes 37 and 38 which are electrodes for use are provided.
In this embodiment, the tip portions of the vibrating arms 35 and 36 are preferably widened in a slightly tapered shape so that the weight is increased, thereby serving as a weight. Thereby, the bending vibration of the vibrating arm is easily performed.

Further, the piezoelectric vibrating piece 32-1 has a width direction of the base 51 at the other end (the left end in the figure) separated from the one end where the vibrating arm of the base 51 is formed by a predetermined distance BL2 (base length) in FIG. And extending in parallel with the vibrating arms 35 and 36 in the extending direction (rightward in FIG. 12) of the vibrating arms 35 and 36 at positions on both outer sides of the vibrating arms 35 and 36. 61 and 62 are provided.
The tuning fork-shaped outer shape of the piezoelectric vibrating piece 32-1 and the long groove provided in each vibrating arm are precisely formed by wet etching or dry etching a material such as a quartz wafer with a hydrofluoric acid solution, for example. can do.

The support arm 61 will be described with reference to FIG. 14. In order to obtain a stable support structure, the length dimension u should be 60 to 80 percent of the total length a of the piezoelectric vibrating piece 32-1. Is necessary.
In addition, although not shown in the drawings as described in other embodiments described later, a part or a part of the part between the joint part of the support arm 61 and the base part 51 is a part or structure with reduced rigidity. A certain cut portion or a reduced width portion may be provided. Thereby, reduction of CI value etc. can be expected.
Further, the outer corner portions 61a and 62a of the supporting arms 61 and 62 are chamfered in an R shape that is inwardly convex or outwardly convex, thereby preventing damage caused by chipping.

Preferably, the base 51 is provided with a recess or notch formed by partially reducing the widthwise dimension of the base 51 on both side edges at a position sufficiently away from the end of the base 51 on the vibrating arm side. Units 71 and 71 are provided. It is preferable that the depths of the cut portions 71 and 71 are reduced to such an extent that they coincide with the outer side edges of the adjacent vibrating arms 35 and 36, respectively. That is, the depth (dimension q in FIG. 14) can be set to about 60 μm, for example.
Thereby, when the vibrating arms 35 and 36 are bent and vibrated, it is possible to suppress vibration leakage from leaking to the base 51 side and propagating to the supporting arms 61 and 62, and to reduce the CI value.

Here, in the present embodiment, the location where the support arms 61 and 62 described above extend, that is, the other end 53 of the base 51 has a distance BL2 that is sufficiently separated from the base 52 of the vibrating arms 35 and 36. Has been.
The distance BL2 is preferably a dimension that exceeds the arm width dimension W2 of the vibrating arms 35 and 36.
That is, when the vibrating arms 35 and 36 of the tuning fork-type vibrating piece flexurally vibrate, the range in which the vibration leakage is transmitted toward the base 51 correlates with the arm width dimension W2 of the vibrating arms 35 and 36. The inventor pays attention to this point, and has the knowledge that the base end of the supporting arms 61 and 62 must be provided at an appropriate position.

Therefore, in the present embodiment, a position exceeding the dimension corresponding to the arm width dimension W2 of the vibrating arm, starting from the base 52 of the vibrating arm, at the base 53 of the supporting arms 61 and 62 is set. By selecting, the structure in which the vibration leakage from the vibrating arms 35 and 36 is more reliably suppressed from propagating to the supporting arms 61 and 62 side can be achieved. Therefore, in order to suppress the CI value and obtain the effect of the support arm described later, the position of 53 is the location of the base portion of the vibrating arms 35 and 36 (that is, one end portion of the base portion 51) 52. It is preferable that the distance is set at a distance of BL2.
For the same reason, it is preferable that the locations where the cut portions 71 and 71 are formed are locations where the location of the base portions 52 of the vibrating arms 35 and 36 exceeds the arm width dimension W2 of the vibrating arms 35 and 36. . For this reason, the notches 71 and 71 are formed at positions closer to the vibrating arm than the portions where the supporting arms 61 and 62 are integrally connected to the base 51.
Since the support arms 61 and 62 are not involved in vibration, there is no special condition for the arm width f (see FIG. 14). However, in order to ensure the support structure, the support arms 61 and 62 may have a larger width than the vibration arm. preferable.

Thus, in this embodiment, the arm width W2 of the vibrating arms in FIG. 12 is about 40 μm to 50 μm, the distance MW2 between the vibrating arms is about 50 μm to 100 μm, and the total length of the piezoelectric vibrating piece 32-3 shown by the dimension a in FIG. It is about 1300 μm to 1600 μm. The dimension b, which is the total length of the vibrating arm, is 1100 to 1400 μm, and the width f of the support arms 61 and 62 is about 50 μm to 100 μm, so that the width dimension e of the base 51 is 200 to 400 μm and the maximum width d of the base 51 400 μm to 600 μm, which is substantially the same as the width of the piezoelectric vibrating reed 1 of FIG. 18, is short in length, and can be sufficiently accommodated in a package of the same size as the conventional one.
Further, in this embodiment, in order to reduce the package size, the distance (dimension p) between the side surface of the base 51 and the supporting arms 61 and 62 is set to 30 to 100 μm.
As described above, the present embodiment can obtain the following operational effects while achieving such downsizing.

In the piezoelectric vibrating piece 32-1 of FIG. 12, since the supporting arms 61 and 62 are joined to the package 57-1 side by the conductive adhesives 43 and 43, the cause is a change in ambient temperature, a drop impact, or the like. As a result, the stress change generated at the joint portion is a bent distance from the joint portion of the supporting arms 61 and 62 to the other end portion 53 of the base portion 51, and further, the length of the base portion 51 exceeding the distance BL2. , The vibration arms 35 and 36 are hardly affected, and the temperature characteristics are particularly good.
In addition, the vibration leakage from the vibrating arms 35 and 36 that bend and vibrate contrary to this is separated by a predetermined length of the base 51 that exceeds the distance BL2 before reaching the supporting arms 61 and 62 that are separated from the base 51. Because of that, it hardly reaches.

Here, if the length of the base portion 51 is extremely short, it is conceivable that the component in which the bending vibration leaks spreads over the entire support arms 61 and 62, and it becomes difficult to control. Severe situations are avoided sufficiently.
Further, in addition to being able to obtain such an action, the support arms 61 and 62 are extended in the width direction from the other end 53 of the base 51 as shown in the figure, and outside the vibrating arms 35 and 36, Since the configuration extends in the same direction as the vibrating arm, the overall size can be made compact.
Further, in this embodiment, as shown in FIG. 14, the tips of the supporting arms 61 and 62 are formed so as to be closer to the base 51 than the tips of the vibrating arms 35 and 36. Also in this point, the size of the piezoelectric vibrating piece 32-1 can be made compact.

For example, with respect to one support arm 61, only one location corresponding to the center of gravity position G (refer to FIG. 12) of the length dimension of the piezoelectric vibrating piece 32-1 is provided for the one support arm 61. You can also choose. However, as in this embodiment, when the electrode portions 31-1 and 31-2 are set and joined by selecting two points that are equidistant from the center of gravity position across the center of gravity position, the joint structure is further strengthened. It is preferable.
When one support arm is joined at one point, it is sufficient that the length of the adhesive application region is 25% or more of the total length a of the piezoelectric vibrating piece 32-1 in FIG. It is preferable in obtaining.
In the case of providing two joining points as in this embodiment, it is preferable that the interval between the joining points is 25% or more of the total length a of the piezoelectric vibrating piece 32-1, in order to obtain sufficient joining strength. .

Further, as can be easily understood as compared with the configuration of FIG. 18, FIG. 18 has a structure in which conductive adhesives 7 and 8 are applied and joined to the extraction electrode 5 and the extraction electrode 6 that are close to each other. Therefore, in order to prevent them from coming into contact with each other, avoid the short circuit and apply the adhesive to a very narrow area (on the package side), or even after joining, perform the joining process while preventing the adhesive from flowing before hardening. It had to be an easy process.
On the other hand, in the piezoelectric vibrating piece 32-1 of FIG. 12, two electrodes that are equidistant from the center of gravity position G of each of the supporting arms 61 and 62 that are separated from each other in the width direction of the package 57-1. Since the conductive adhesives 43, 43, 43, 43 may be applied to the portions 31-1, 31-2, there is almost no difficulty as described above, and there is no fear of a short circuit.
In addition, regarding the piezoelectric vibrating piece 32-1, as shown in FIG. 14, the structure and the operational effects of the portions indicated by the same reference numerals as those in FIG. 3 are the same as those in the first embodiment. .

(Third and fourth embodiments)
FIG. 15 and FIG. 16 show the third embodiment and the fourth embodiment of the piezoelectric vibrating piece, respectively, and these embodiments are examples in which a structure with reduced rigidity is adopted for a part of the support arm. . In these drawings, portions that are the same as those of the piezoelectric vibrating piece 32-1 described in FIGS. 12 to 14 are denoted by the same reference numerals, and redundant description is omitted. Hereinafter, differences will be mainly described.

  In these embodiments, the structures with reduced rigidity are provided at a position between the base 51 and the conductive adhesive 43 that is a joint location. Thereby, even if the vibration leakage due to the bending vibration of the vibrating arm reaches the supporting arm, it can be reduced as much as possible that it is transmitted to the joint location.

In FIG. 15, in the piezoelectric vibrating piece 32-2, the structure with reduced rigidity is the reduced width portions 77 and 77 formed in the middle of the support arms 61-1 and 62-1.
That is, in each of the supporting arms 61-1 and 62-1, the arm width is gradually reduced toward the vicinity of the middle in the length direction, and the vicinity of the middle is the narrowest reduced width portion. ing. For this reason, the reduced width portions 77 and 77 are places where the rigidity of the support arm is the lowest, and the propagated strain tends to concentrate here, so that the vibration leakage is transmitted to the places of the conductive adhesives 43 and 43. A difficult structure can be obtained. Moreover, such reduced width portions 77 and 77 can be easily formed by a technique such as etching when forming the outer shape of the piezoelectric vibrating piece 32-2.

  In FIG. 16, in the piezoelectric vibrating piece 32-3, the structure with reduced rigidity is the cut portions 75, 75 and 76, 76 formed in the middle of the support arms 61-2 and 62-2. Since the support arms 61-2 and 62-2 have the same structure, only the support arm 61-2 will be described. The cut portion cut in the width direction from the outside of the support arm 61-2 is the cut portion 75. The cut portion cut in the width direction from the inside is the cut portion 76.

If both the notches 75 and 76 are provided, leakage of bending vibration of the vibrating arms 35 and 36 can be more reliably prevented, but the effect of reducing leakage of vibration can be obtained. In addition, if both of the cut portions 75 and 76 are formed, the rigidity of the support arm 61-2 is reduced accordingly, but if one of them is provided, there is no significant reduction in strength.
That is, when emphasizing the function of preventing vibration leakage, it is better to provide both the cut portions 75 and 76, and when emphasizing the strength of the support arm 61-2 itself, either one is formed. do it. Further, the cut portions 75 and 76 can be easily formed by a technique such as etching when forming the outer shape of the piezoelectric vibrating piece 32-3.

FIG. 17 is a diagram showing a schematic configuration of a digital mobile phone device as an example of an electronic apparatus using the piezoelectric device according to the above-described embodiment of the present invention.
In the figure, a microphone 308 for receiving the voice of the sender and a speaker 309 for outputting the received content as a voice output are provided. The CPU (Central Processing Unit) 301 is provided.
In addition to modulation and demodulation of transmission / reception signals, the CPU 301 includes an information input / output unit 302 including an LCD as an image display unit and operation keys for inputting information, and an information storage unit (memory) 303 including a RAM, a ROM, and the like. Control is to be performed. For this reason, the piezoelectric device 30 and those of other embodiments are attached to the CPU 301, and the output frequency of the clock is adapted to the control contents by a predetermined frequency dividing circuit (not shown) built in the CPU 301. It is made to use as a signal.

  The CPU 301 is further connected to a temperature compensated crystal oscillator (TCXO) 305, and the temperature compensated crystal oscillator 305 is connected to the transmitter 307 and the receiver 306. Thus, even if the basic clock from the CPU 301 fluctuates when the environmental temperature changes, it is corrected by the temperature compensated crystal oscillator 305 and supplied to the transmission unit 307 and the reception unit 306.

  As described above, the piezoelectric device 30 according to the above-described embodiment and the piezoelectric devices of other embodiments can be used for an electronic apparatus such as the digital cellular phone device 300 including the control unit. In this case, by using a piezoelectric vibrating piece having a low CI value and good vibration characteristics, excellent performance can be exhibited, and the reliability of the product is improved in terms of impact resistance and the like.

The present invention is not limited to the above-described embodiment. In the above-described embodiment, only a configuration in which a pair of vibrating arms extends in parallel from one base portion is shown, but a plurality of pairs of vibrating arms may extend from one base portion. Furthermore, each configuration of each of the embodiments described above can be appropriately combined or omitted, and can be combined with other configurations not shown.
Further, the present invention is not limited to the case where the piezoelectric vibrating piece or the piezoelectric vibrating piece and the integrated circuit are housed in the box-shaped package, but the piezoelectric vibrating piece is housed in the cylindrical container, and the piezoelectric vibrating piece is the gyro sensor. It can be applied to any piezoelectric device using a piezoelectric vibrating piece, regardless of the name of a piezoelectric vibrator, a piezoelectric oscillator, or the like.

The schematic plan view which shows embodiment of the piezoelectric device of this invention. BB schematic sectional drawing of FIG. FIG. 2 is a schematic plan view of a piezoelectric vibrating piece used in the piezoelectric device of FIG. 1. The CC sectional view taken on the line of FIG. The graph which shows the relationship between the constriction position of the vibrating arm of the piezoelectric vibrating piece of FIG. 3, and CI value. The graph which shows the relationship between the constriction position of the vibrating arm of the piezoelectric vibrating piece of FIG. 3, and CI value ratio. The graph which shows the relationship between the width reduction ratio of the arm width of the vibration arm of the piezoelectric vibrating piece of FIG. 3, and CI value ratio. 4 is a graph showing the relationship between the width dimension of the first reduced width portion and the CI value of the piezoelectric vibrating piece in FIG. 3. FIG. 2 is a circuit diagram illustrating an example of an oscillation circuit using the piezoelectric vibrating piece of FIG. 1. The flowchart which shows an example of the manufacturing method of the piezoelectric device of FIG. The figure which shows the coordinate axis of a crystal Z board. The schematic plan view which shows 2nd Embodiment of a piezoelectric device. The DD sectional view taken on the line of FIG. FIG. 5 is a schematic enlarged plan view of a piezoelectric vibrating piece according to a second embodiment. FIG. 6 is a schematic plan view showing a third embodiment of the piezoelectric vibrating piece in FIG. 1. FIG. 6 is a schematic plan view showing a fourth embodiment of the piezoelectric vibrating piece in FIG. 1. 1 is a diagram showing a schematic configuration of a digital mobile phone device as an example of an electronic apparatus using a piezoelectric device according to an embodiment of the present invention. FIG. 6 is a schematic plan view of a conventional piezoelectric vibrating piece. The AA cut | disconnection end elevation of FIG. The graph which shows the drive level characteristic of the piezoelectric vibrating piece of FIG. The graph which shows the dispersion | variation in CI value ratio in the piezoelectric vibrating piece of FIG.

Explanation of symbols

  30, 30-1 ... Piezoelectric device, 32, 32-1, 32-2, 32-3 ... Piezoelectric vibrating piece, 33, 34 ... Long groove, 35, 36 ... Vibrating arm, TL ..First reduced width portion, CL ... second reduced width portion, 300 ... digital mobile phone device

Claims (13)

A base formed of piezoelectric material;
A plurality of vibrating arms formed integrally with the base and extending from one end of the base so as to intersect an electric axis direction (X-axis direction) of the piezoelectric material;
A long groove formed in each vibrating arm along the longitudinal direction of the vibrating arm;
A driving electrode formed in the long groove;
A supporting arm that extends in the width direction of the piezoelectric vibrating piece from a joint portion with the base that is a predetermined distance away from the one end of the base, and extends along the longitudinal direction outside the vibrating arm;
With
Each of the vibrating arms has a reduced width portion whose width is gradually reduced from the base side toward the distal end side of the vibrating arm, and the change point is defined by using the front end of the reduced width portion as a change point P. Extending from the change point P toward the tip side so that the width dimension is equally constant or increased compared to the width dimension at the position of P;
The long groove has a tip on the tip side of the vibrating arm, and the depth of the long groove increases from the inner wall surface on the minus X-axis side in the long groove toward the plus X-axis direction. It has a shape with an inclined bottom,
The change point P is located further on the distal end side of the vibrating arm than the distal end portion of the long groove,
A side surface of each vibration arm has a deformed portion protruding in the plus X-axis direction within 5 μm. The base portion has a cut portion formed by shrinking the piezoelectric material in the width direction, and the cut portion is 1.2 times the width of the vibrating arm from the root of each vibrating arm. 2. The piezoelectric vibrating piece according to claim 1, wherein the piezoelectric vibrating piece is formed in the base portion at a distance above the distance.   The width dimension of each of the vibrating arms includes a first reduced width portion that is reduced toward the distal end side at a base portion of the vibrating arm with respect to the base portion, and an end of the first reduced width portion. 3. The piezoelectric vibrating piece according to claim 1, further comprising a second reduced width portion that is gradually reduced in width toward the distal end side as compared with the first reduced width portion. .   The base portion has a cut portion formed by shrinking the piezoelectric material in the width direction, and the cut portion is 1.2 times the width of the vibrating arm from the root of each vibrating arm. 2. The piezoelectric vibrating piece according to claim 1, wherein the piezoelectric vibrating piece is formed in the base portion at a distance above the distance.   The ratio of the length of the long groove to the arm length of the vibrating arm is 61.5%, and the maximum width / minimum width as the width reduction width ratio of the vibrating arm is 1.06 or more. Item 5. The piezoelectric vibrating piece according to any one of Items 1 to 4.   The piezoelectric vibrating piece according to claim 3, wherein a width of the first reduced width portion is 11 μm or more.   5. The piezoelectric vibrating piece according to claim 2, wherein the cut portion is located closer to the vibrating arm than the joint portion.   The piezoelectric vibration according to claim 6 or 7, wherein a length of the support arm is set so that a tip of the support arm is closer to the base than a tip of the vibrating arm. Piece.   A part of the support arm is joined to the base, and a part between the part joined to the base and the joint part with the base is located on both sides of the part. The piezoelectric vibrating piece according to claim 7 or 8, wherein the piezoelectric vibrating piece has a structure having lower rigidity than a portion of the supporting arm.   10. The piezoelectric vibrating piece according to claim 9, wherein a thickness of the part of the support arm having the reduced rigidity is smaller than a part of the support arm positioned on both sides thereof.   11. A piezoelectric device comprising the piezoelectric vibrating piece according to claim 1 housed in a package or a case. A mobile phone device using a piezoelectric device in which a piezoelectric vibrating piece is accommodated in a package or case,
The piezoelectric vibrating piece is
A base formed of piezoelectric material;
A plurality of vibrating arms formed integrally with the base and extending from one end of the base so as to intersect an electric axis direction (X-axis direction) of the piezoelectric material;
A long groove formed in each vibrating arm along the longitudinal direction of the vibrating arm;
A driving electrode formed in the long groove;
A supporting arm that extends in the width direction of the piezoelectric vibrating piece from a joint portion with the base that is a predetermined distance away from the one end of the base, and extends along the longitudinal direction outside the vibrating arm;
With
Each of the vibrating arms has a reduced width portion whose width is gradually reduced from the base side toward the distal end side of the vibrating arm, and the change point is defined by using the front end of the reduced width portion as a change point P. Extending from the change point P toward the tip side such that the width dimension is equally constant or increased compared to the width dimension at the position of P;
The long groove has a tip on the tip side of the vibrating arm, and the depth of the long groove increases from the inner wall surface on the minus X-axis side in the long groove toward the plus X-axis direction. It has a shape with an inclined bottom,
The change point P is located further on the distal end side of the vibrating arm than the distal end portion of the long groove,
The side surface of each vibrating arm is configured to obtain a clock signal for control by a piezoelectric device having the piezoelectric vibrating piece in which a deformed portion protruding in the plus X-axis direction is formed within 5 μm. Mobile phone device. An electronic device using a piezoelectric device in which a piezoelectric vibrating piece is accommodated in a package or case,
The piezoelectric vibrating piece is
A base formed of piezoelectric material;
A plurality of vibrating arms formed integrally with the base and extending from one end of the base so as to intersect an electric axis direction (X-axis direction) of the piezoelectric material;
A long groove formed in each vibrating arm along the longitudinal direction of the vibrating arm;
A driving electrode formed in the long groove;
A supporting arm that extends in the width direction of the piezoelectric vibrating piece from a joint portion with the base that is a predetermined distance away from the one end of the base, and extends along the longitudinal direction outside the vibrating arm;
With
Each of the vibrating arms has a reduced width portion whose width is gradually reduced from the base side toward the distal end side of the vibrating arm, and the change point is defined by using the front end of the reduced width portion as a change point P. Extending from the change point P toward the tip side such that the width dimension is equally constant or increased compared to the width dimension at the position of P;
The long groove has a tip on the tip side of the vibrating arm, and the depth of the long groove increases from the inner wall surface on the minus X-axis side in the long groove toward the plus X-axis direction. It has a shape with an inclined bottom,
The change point P is located further on the distal end side of the vibrating arm than the distal end portion of the long groove,
The side surface of each vibrating arm is configured to obtain a clock signal for control by a piezoelectric device having the piezoelectric vibrating piece in which a deformed portion protruding in the plus X-axis direction is formed within 5 μm. ,Electronics.

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