Patent Application
20140368288
The entire disclosure of Japanese Patent Application No. 2013-128014 filed Jun. 18, 2013 is expressly incorporated by reference herein.
1. Technical Field
The invention relates to a resonator element, a resonator, an oscillator, an electronic device, and a moving object.
2. Related Art
Hitherto, resonator elements using quartz crystal have been known. Such resonator elements have excellent frequency-temperature characteristics. Accordingly, the resonator elements are widely used as reference frequency sources, signal transmission sources, and the like of various electronic devices.
A resonator element disclosed in JP-A-2011-19159 includes a base portion and a pair of vibrating arms collaterally extending from the base portion. The resonator element is fixed to a package through conductive adhesive members by two fixation portions provided in the base portion. However, in such a configuration, the two fixation portions are disposed at a position where vibrations of the vibrating arms are likely to be transmitted. Accordingly, when a vibrating piece is reduced in size, there is a concern that the resonator element may be greatly affected by vibration leakage.
In addition, a resonator element disclosed in JP-A-2002-141770 includes a base portion, a pair of vibrating arms collaterally extending from the base portion, and a supporting arm extending between the pair of vibrating arms from the base portion. The resonator element is fixed to a package through conductive adhesive members by two fixation portions provided in the supporting arm.
However, in such a configuration, there is a problem in that a Q value may be decreased according to the positions of the two fixation portions in the supporting arm and a positional relationship between the two fixation portions.
An advantage of some aspects of the invention is to provide a resonator element capable of reducing a decrease in the Q value, and a resonator, an oscillator, an electronic device, and a moving object which include the resonator element.
The invention can be implemented as the following application examples.
This application example is directed to a resonator element including a base portion; a pair of vibrating arms that extend in a first direction from the base portion and are lined up along a second direction perpendicular to the first direction; and a supporting arm that extends in the first direction from the base portion and is disposed between the pair of vibrating arms when seen in a plan view. The supporting arm is provided with a fixed region that is attached to an object through a fixation member between a centroid of the resonator element and the base portion when seen in a plan view.
According to this configuration, the resonator element capable of reducing a reduction in a Q value is obtained.
This application example is directed to the resonator element according to the application Example described above, wherein the fixed region has a length along the first direction which is larger than a length along the second direction.
According to this configuration, the resonator element capable of further reducing a reduction in a Q value is obtained.
This application example is directed to the resonator element according to the application example described above, wherein the fixed region has a length along the first direction which is equal to or greater than twice and equal to or less than five times the length along the second direction.
Since the fixed region is larger in length in the longitudinal direction of the resonator element, it is possible to fix the resonator element to a case in a balanced manner.
This application example is directed to the resonator element according to the application example described above, wherein, when a distance along the first direction between the centroid and the base portion when seen in a plan view is set to L10, the distance along the first direction between a center of the fixed region in the first direction and the base portion is equal to or greater than 0.15×L10 and equal to or less than 0.30×L10.
Since this range is a region which is not likely to be affected by vibration of the vibrating arms, the fixed region is disposed centering on this position. Thus, the resonator element in which a reduction in a Q value due to vibration leakage is further reduced is obtained.
This application example is directed to the resonator element according to the application example described above, wherein, when a distance along the first direction between the centroid and the base portion when seen in a plan view is set to L10, the distance of the fixed region along the first direction is equal to or greater than 0.589×L10 and equal to or less than L10.
The resonator element in which a reduction in a Q value due to vibration leakage is further reduced is obtained.
This application example is directed to the resonator element according to the application example described above, wherein the supporting arm overlaps the centroid when seen in a plan view.
Thus, the resonator element capable of reducing the influence of vibration of the vibrating arms and reducing a reduction in a Q value caused by vibration leakage is obtained.
This application example is directed to the resonator element according to the application example described above, wherein the fixed region includes, when seen in a plan view, a first fixation portion, and a second fixation portion which is spaced apart from the first fixation portion and is positioned on the distal end side of the supporting arm with respect to the first fixation portion.
Thus, it is possible to reduce contact between the fixation members in a state of being mounted onto an object.
This application example is directed to the resonator element according to the application example described above, wherein a distance along the first direction between the first fixation portion and the second fixation portion is equal to or greater than 20 μm.
Thus, it is possible to further reduce contact between the fixation members in a state of being mounted onto an object.
This application example is directed to a resonator including the resonator element according to the application example and a package that accommodates the resonator element.
Thus, a resonator with high reliability is obtained.
This application example is directed to an oscillator including the resonator element according to the application example and an oscillation circuit.
Thus, an oscillator with high reliability is obtained.
This application example is directed to an electronic device including the resonator element according to the application example.
Thus, an electronic device with high reliability is obtained.
This application example is directed to a moving object including the resonator element according to the application example.
Thus, a moving object with high reliability is obtained.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Hereinafter, a resonator element, a resonator, an oscillator, an electronic device, and a moving object according to the invention will be described in detail with reference to preferred embodiments shown in the diagrams.
First, the resonator according to the invention will be described.
As shown in
As shown in
A material of the base 91 is not particularly limited, and various ceramics such as aluminum oxide can be used. In addition, although a material of the lid 92 is not particularly limited, it is preferable to use a member having a linear expansion coefficient similar to that of the material of the base 91. For example, when the above-described ceramic is used as a material of the base 91, it is preferable to use an alloy such as Kovar. Meanwhile, the bonding of the base 91 and the lid 92 is not particularly limited. For example, the base and the lid may be bonded to each other through a metalization layer.
In addition, connecting terminals 951 and 961 are formed on the bottom surface of the concave portion 911 of the base 91. A first conductive adhesive member (fixation member) 11 is provided on the connecting terminal 951, and a second conductive adhesive member (fixation member) 12 is provided on the connecting terminal 961. The resonator element 2 is fixed to the base 91 through the first and second conductive adhesive members 11 and 12. Meanwhile, materials of the first and second conductive adhesive members 11 and 12 are not particularly limited as long as the materials have conductive and adhesive properties. For example, a conductive adhesive member including an epoxy-based, acrylic-based, silicone-based, bismaleimide-based, polyester-based, or polyurethane-based resin mixed with a conductive filler such as silver particles, or a metal bump such as a gold bump, a silver bump, or a copper bump can be used.
In addition, the connecting terminal 951 is electrically connected to an external terminal 953, provided on the bottom surface of the base 91, through a through electrode (not shown) passing through the base 91. Similarly, the connecting terminal 961 is electrically connected to an external terminal 963, provided on the bottom surface of the base 91, through a through electrode (not shown) passing through the base 91. Materials of the connecting terminals 951 and 961, the external terminals 953 and 963, and the through electrode are not particularly limited as long as the materials have conductivity. For example, the terminals and the electrode can be formed of a metal coating in which a coat such as gold (Au), silver (Ag), or copper (Cu) is laminated on a base layer such as chromium (Cr), nickel (Ni), or tungsten (W).
As shown in
The quartz crystal substrate 3 is constituted by a Z-cut quartz crystal plate. The Z-cut quartz crystal plate refers to a quartz crystal substrate having a Z-axis as its thickness direction. Meanwhile, it is preferable that the Z-axis conforms with the thickness direction of the quartz crystal substrate 3. However, from the viewpoint of reducing a change in frequency with temperature near room temperature, the Z-axis may be inclined slightly with respect to the thickness direction.
That is, in a case where the inclination angle is set to θ degrees)(−5°≦θ≦15°, it is assumed that the X-axis of a rectangular coordinate system constituted by the X-axis as the electrical axis of quartz crystal, the Y-axis as the mechanical axis thereof, and the Z-axis as the optical axis thereof is a rotation axis. When an axis obtained by inclining the Z-axis at θ degrees so that a +Z side rotates in the −Y direction of the Y-axis is set to a Z′-axis and an axis obtained by inclining the Y-axis at θ degrees so that a +Y side rotates in the +Z direction of the Z-axis is set to a Y′-axis, the quartz crystal substrate 3 is obtained in which a direction along the Z′-axis is set to the thickness thereof and a surface including the X-axis and the Y′-axis is set to the principal surface thereof.
Meanwhile, the thickness D of the quartz crystal substrate 3 is not particularly limited, but is preferably less than 70 μm. Based on such a numerical range, when the quartz crystal substrate 3 is formed (patterned) by, for example, wet etching, it is possible to effectively prevent unnecessary portions (portions necessary to be removed) from remaining in a boundary between a vibrating arm 5 and a base portion 4, a boundary between an arm portion 51 to be described later and a hammerhead 59 as a weight portion, and the like. For this reason, it is possible to obtain the resonator element 2 capable of effectively reducing vibration leakage. From a different point of view, the thickness D is preferably equal to or greater than 70 μm and equal to or less than 300 μm, and more preferably equal to or greater than 100 μm and equal to or less than 150 μm. Based on such a numerical range, it is possible to form first and second driving electrodes 84 and 85 to be described later to be wide in the side surfaces of the vibrating arm 5 and a vibrating arm 6, and thus it is possible to lower a CI value.
The weight portion is configured as a wide width portion 59 which is larger in length along the X-axis direction than the arm portion 51, but the invention is not limited thereto. The weight portion may have a higher mass density per unit length than that of the arm portion 51. For example, the weight portion may be configured to have a length that is the same as the length of the arm portion along the X-axis direction and to have a thickness along the Z-axis direction which is larger than that of the arm portion. In addition, the weight portion may be configured such that a metal such as Au is provided thickly on the surface of the arm portion which corresponds to the weight portion. Further, the weight portion may be formed of a material having a higher mass density than that of the arm portion.
As shown in
The base portion 4 has a substantially plate shape that extends on the XY plane and has a thickness in the Z-axis direction. The base portion 4 includes a portion (main body 41), which supports and connects the vibrating arms 5 and 6, and a width-decreasing portion 42 to reduce vibration leakage.
The width-decreasing portion 42 is provided on the base end side (side opposite to a side on which the vibrating arms 5 and 6 extend) of the main body 41. In addition, the width (length along the X-axis direction) of the width-decreasing portion 42 gradually decreases as a distance from each of the vibrating arms 5 and 6 increases. Due to the width-decreasing portion 42, it is possible to effectively reduce the vibration leakage of the resonator element 2.
This will be specifically described as follows. Meanwhile, in order to simplify the description, it is assumed that the shape of the resonator element 2 is symmetrical about a predetermined axis parallel to the Y-axis.
First, as shown in
In contrast, as shown in
Meanwhile, in this embodiment, although the contour of the width-decreasing portion 42 has an arch shape, the shape of the contour of the width-decreasing portion is not limited thereto as long as the operation described above can be realized. For example, the width-decreasing portion may be a width-decreasing portion having a contour that is formed stepwise by a plurality of straight lines or a width-decreasing portion having a contour that is formed to have a substantially arch shape by a plurality of straight lines.
The vibrating arms 5 and 6 extend in the +Y-axis direction (first direction) from the distal end of the base portion 4 so as to be lined up in the X-axis direction (second direction) and parallel to each other. Each of the vibrating arms 5 and 6 has an elongated shape. The base end of each of the vibrating arms is a fixed end, and the distal end is a free end.
In addition, the vibrating arms 5 and 6 include arm portions 51 and 61 and hammerheads 59 and 69 as weight portions provided at the distal ends of the arm portions 51 and 61. Meanwhile, since the vibrating arms 5 and 6 have the same configuration, the vibrating arm 5 will be described as a representative vibrating arm hereinafter, and description of the vibrating arm 6 will be omitted.
As shown in
Although the depth of each of the grooves 52 and 53 is not particularly limited, it is preferable that the relation of 60%≦(D1+D2)/D≦95% is satisfied assuming that the depth of the groove 52 is D1 and the depth of the groove 53 is D2 (in this embodiment, D1=D2). Since a heat transfer path becomes longer by satisfying such a relationship, it is possible to more effectively reduce thermoelastic loss in an adiabatic-like region (to be described later in detail).
Meanwhile, it is preferable to form the grooves 52 and 53 by adjusting the positions of the grooves 52 and 53 in the X-axis direction with respect to the position of the vibrating arm 5 so that the cross-sectional centroid of the vibrating arm 5 matches the center of the cross-sectional shape of the vibrating arm 5. In this manner, since it is possible to reduce an unnecessary vibration (specifically, an oblique vibration having an out-of-plane component) of the vibrating arm 5, it is possible to reduce vibration leakage. In this case, since it is also possible to reduce driving for an unnecessary vibration, a driving region is relatively increased in size. Therefore, it is possible to reduce the CI value.
In addition, assuming that the widths (lengths in the X-axis direction) of bank portions (principal surfaces lined up with the groove 52 interposed therebetween along the width direction perpendicular to the longitudinal direction of the vibrating arm) 511a, which are positioned on both sides of the groove 52 of the principal surface 511 in the X-axis direction, and bank portions 512a, which are positioned on both sides of the groove 53 of the principal surface 512 in the X-axis direction, are W3, it is preferable to satisfy the relation of 0 μm<W3≦20 μm. In this manner, the CI value of the resonator element 2 becomes sufficiently low. In the numerical range described above, it is preferable to satisfy the relation of 5 μm<W3≦9 μm. In this manner, in addition to the effects described above, it is possible to reduce thermoelastic loss. In addition, it is also preferable to satisfy the relation of 0 μm<W3≦5 μm. In this manner, it is possible to further lower the CI value of the resonator element 2.
The hammerhead 59 has a substantially rectangular shape in which the X-axis direction is a longitudinal direction when seen in a plan view. The hammerhead 59 has a width (length in the X-axis direction) which is greater than that of the arm portion 51, and protrudes to both sides in the X-axis direction from the arm portion 51. By forming the hammerhead 59 in such a configuration, it is possible to increase the mass of the hammerhead 59 while suppressing the total length L of the vibrating arm 5. In other words, when the total length L of the vibrating arm 5 is fixed, it is possible to secure the arm portion 51 being as long as possible without reducing the mass effect of the hammerhead 59. For this reason, it is possible to increase the width of the vibrating arm 5 in order to obtain a desired resonance frequency (for example, 32.768 kHz). As a result, since a heat transfer path to be described later becomes longer, thermoelastic loss is reduced and the Q value is improved.
In addition, the center of the hammerhead 59 in the X-axis direction may be slightly shifted from the center of the vibrating arm 5 in the X-axis direction. For example, as shown in
In addition, when the total length (length in the Y-axis direction) of the vibrating arm 5 is set to L and the length (length in the Y-axis direction) of the hammerhead 59 is set to H, it is preferable that the vibrating arm 5 satisfies the relation of 1.2%<H/L<30.0% and satisfies the relation of 4.6%<H/L<22.3%. When such a numerical range is satisfied, the CI value of the resonator element 2 is low. Therefore, the vibration loss is small, and the resonator element 2 having excellent vibration characteristics is obtained. Here, in this embodiment, the base end of the vibrating arm 5 is set in a position of the line segment, which connects a place where the side surface 514 is connected to the base portion 4 and a place where the side surface 513 is connected to the base portion 4, in the center of the width (length in the X-axis direction) of the vibrating arm 5. In addition, the base end of the hammerhead 59 is set in a position where the width thereof is 1.5 times the width of the arm portion 51, in a tapered portion provided in the distal end of the arm portion 51.
In addition, when the width (length in the X-axis direction) of the arm portion 51 is set to W1 and the width (length in the X-axis direction) of the hammerhead 59 is set to W2, it is preferable that the relation of 1.5≦W2/W1≦10.0 is satisfied, and it is more preferable that the relation of 1.6≦W2/W1≦7.0 is satisfied. By satisfying such a numerical range, it is possible to secure a large width for the hammerhead 59. For this reason, even if the length H of the hammerhead 59 is relatively small as described above, it is possible to sufficiently exhibit the mass effect of the hammerhead 59.
Meanwhile, by setting L≦2 mm, preferably, L≦1 mm, it is possible to obtain a small resonator element used in an oscillator that is mounted in a portable music device, an IC card, and the like. In addition, by setting W1≦100 μm, preferably, W1≦50 μm, it is also possible to obtain a resonator element, which resonates at a low frequency and which is used in an oscillation circuit for realizing low power consumption, in the range of L described above. In addition, in the case of an adiabatic-like region, when the vibrating arms 5 and 6 extend in the Y-axis direction in the quartz crystal Z plate and bend and vibrate in the X direction as in this embodiment, it is preferable that W1≧12.8 μm is satisfied. When the vibrating arms 5 and 6 extend in the X direction in the quartz crystal Z plate and bend and vibrate in the Y direction, it is preferable that W1≧14.4 μm is satisfied. When the vibrating arms 5 and 6 extend in the Y direction in the quartz crystal X plate and bend and vibrate in the Z direction, it is preferable that W1≧15.9 μm is satisfied. In this manner, since an adiabatic-like region can be reliably obtained, thermoelastic loss is reduced by the formation of the grooves 52, 53, 62, and 63, and the Q value is improved. In addition, due to driving in a region where the grooves 52, 53, 62, and 63 are formed, the electric field efficiency is high, and the driving area is secured. Accordingly, the CI value is reduced.
The supporting arm 7 is positioned between the vibrating arms 5 and 6 and extends in the +Y-axis direction from the distal end of the base portion 4. In addition, the distal end of the supporting arm 7 is positioned on the base portion 4 side with respect to the base ends of the hammerheads 59 and 69. In particular, in this embodiment, the distal end of the supporting arm 7 is positioned on the base portion 4 side with respect to the centroid G when seen in a plan view. In addition, the width (length in the X-axis direction) of the supporting arm 7 is substantially constant along the extension direction (Y-axis direction).
Until now, the external form of the quartz crystal substrate 3 has been described. As shown in
The fixed region R has the first fixation portion R1 and the second fixation portion R2 which are spaced apart from each other in the Y-axis direction. The first fixation portion R1 is fixed to the base 91 by the conductive adhesive member 11, and the second fixation portion R2 is fixed to the base 91 by the conductive adhesive member 12. Since the first fixation portion R1 and the second fixation portion R2 are disposed so as to be spaced apart from each other, it is possible to prevent contact (short circuit) between the conductive adhesive members 11 and 12 provided in the fixation portions. Although a separation distance between the first and second fixation portions R1 and R2 is not particularly limited, it is preferable that the distance is, for example, equal to or greater than 20 μm, and it is more preferable that the distance is equal to or greater than 50 μm. In this manner, it is possible to more effectively prevent the contact between the conductive adhesive members 11 and 12.
Meanwhile, an upper limit of the separation distance between the first and second fixation portions R1 and R2 is a value obtained by subtracting the sum of the lengths of the first and second fixation portions R1 and R2 along the Y-axis direction from the length (distance) along the Y-axis direction between the base end (boundary between the supporting arm 7 and the base portion 4) of the supporting arm 7 and the centroid G when seen in a plan view, or a value obtained by subtracting the sum of the lengths of the first and second fixation portions R1 and R2 along the Y-axis direction from the length (distance) along the Y-axis direction of the supporting arm 7 when seen in a plan view.
Meanwhile, the first and second fixation portions R1 and R2 have a circular shape, but the plan-view shapes thereof are not limited thereto. The first and second fixation portions may have an elliptical shape or an oval shape, may have a polygonal shape such as a triangular shape, a quadrangular shape, or a pentagonal shape, or may have an irregular shape. In addition, the diameters of the first and second fixation portions R1 and R2 are not particularly limited, but can be set to, for example, approximately equal to or greater than 60 μm and equal to or less than 100 μm. Thus, it is possible to sufficiently secure contact areas with the conductive adhesive members 11 and 12 and to strongly fix the resonator element 2 to the base 91.
As described above, in the resonator element 2, vibrations of the vibrating arms 5 and 6 are not likely to be transmitted to the supporting arm 7 by the width-decreasing portion 42 of the base portion 4. For this reason, the first and second fixation portions R1 and R2 are provided in the supporting arm 7, and thus it is possible to effectively reduce vibration leakage through the conductive adhesive members 11 and 12.
In addition, the second fixation portion R2 is positioned on the distal end side of the base portion 4 with respect to the first fixation portion R1, and is provided to be parallel to the first fixation portion R1 in the Y-axis direction. In addition, the centers of the first and second fixation portions R1 and R2 are positioned at the center of the supporting arm 7 in the width direction (X-axis direction) and are positioned on a straight line L1 parallel to the Y-axis when seen in a plan view. Thus, it is possible to fix the resonator element 2 to the base 91 in a balanced manner.
As shown in
In addition, when the length (distance) between the centroid G of the resonator element 2 and the base end of the supporting arm 7 (distal end of the base portion 4) is set to L10 when seen in a plan view in the Y-axis direction, the fixed region R is preferably configured such that a center O5 of the fixed region R in the Y-axis direction is positioned in a range O1 of a length of 0.15×L10 to 0.30×L10 toward the distal end from the base end of the supporting arm 7 when seen in a plan view. Since the range O1 is a place which is less likely to be affected by vibrations of the vibrating arms 5 and 6, the fixed region R is disposed centering on this position, and thus it is possible to particularly effectively reduce the vibration leakage through the conductive adhesive members 11 and 12.
The electrode 8 includes a first driving electrode 84, a second driving electrode 85, a first connection electrode 81 connected to the first driving electrode 84, and a second connection electrode 82 connected to the second driving electrode 85.
As shown in
In addition, as shown in
Materials of the first and second driving electrodes 84 and 85 and the first and second connection electrodes 81 and 82 are not particularly limited. The electrodes can be formed of a metal material such as gold (Au), a gold alloy, platinum (Pt), aluminum (Al), an aluminum alloy, silver (Ag), a silver alloy, chromium (Cr), a chromium alloy, nickel (Ni), a nickel alloy, copper (Cu), molybdenum (Mo), niobium (Nb), tungsten (W), iron (Fe), titanium (Ti), cobalt (Co), zinc (Zn), or zirconium (Zr), or a conductive material such as indium tin oxide (ITO).
As specific configurations of the first and second driving electrodes 84 and 85 and the first and second connection electrodes 81 and 82, a configuration can be adopted in which an Au layer of equal to or less than 700 Å is formed on a Cr layer of equal to or less than 700 Å, for example. In particular, since Cr and Au have a great thermoelastic loss, the Cr layer and the Au layer are preferably set to equal to or less than 200 Å. When insulation breakdown resistance is increased, the Cr layer and the Au layer are preferably set to equal to or greater than 1000 Å. Further, since Ni has a thermal expansion coefficient close to that of quartz crystal, thermal stress caused by electrodes is reduced by using a Ni layer as a foundation layer in place of the Cr layer, and thus it is possible to obtain a resonator element with a good long-term reliability (aging characteristics).
Meanwhile, the hammerheads 59 and 69 as weight portions are configured as wide width portions of which the lengths along the X-axis direction are longer than those of the arm portions 51 and 61. However, the invention is not limited thereto, and the mass density per unit length of the hammerheads may be greater than those of the arm portions 51 and 61. For example, the weight portion may be configured to have a length that is the same as the lengths along the X-axis direction of the arm portions 51 and 61 and to have a thickness along the Z-axis direction which is larger than those of the arm portions. In addition, the weight portion may be configured such that a metal such as Au is provided thickly on the surfaces of the arm portions 51 and 61 which correspond to the weight portion. Further, the weight portion may be formed of a material having a higher mass density than those of the arm portions 51 and 61.
Until now, the resonator element 2 has been described. As described above, in the resonator element 2, the grooves 52 and 53 and the grooves 62 and 63 are formed in the vibrating arm 5 and the vibrating arm 6 to reduce thermoelastic loss. Hereinafter, this will be described concretely below by using the vibrating arm 5 as an example.
As described above, the vibrating arm 5 bends and vibrates substantially in the in-plane direction by applying an alternating voltage between the first and second driving electrodes 84 and 85. As shown in
In a resonator element that vibrates in a bending vibration mode and has the same configuration as the resonator element 2, when a bending vibration frequency (mechanical bending vibration frequency) f of the vibrating arm 5 changes, the Q value is minimized when the bending vibration frequency of the vibrating arm 5 conforms with a thermal relaxation frequency fm. The thermal relaxation frequency fm can be calculated by an expression of fm=1/(2πτ) (where, in the expression, π denotes the circular constant, and τ denotes a relaxation time required for a difference in temperature to become e−1 times by heat conduction, assuming that e is Napier's constant).
In addition, if a thermal relaxation frequency of a flat plate structure (structure having a rectangular cross-sectional shape) is fm0, fm0 can be calculated by the following expression.
fm0=πk/(2ρCpa2) (1)
Meanwhile, π is the circular constant, k is the thermal conductivity of the vibrating arm 5 in the vibration direction (X-axis direction), ρ is the mass density of the vibrating arm 5, Cp is the heat capacity of the vibrating arm 5, and a is the width of the vibrating arm 5 in the vibration direction. When the constants of the material itself (that is, quartz crystal) of the vibrating arm 5 are input as the thermal conductivity k, the mass density ρ, and the heat capacity Cp in Expression (1), the calculated thermal relaxation frequency fm0 is a value when the grooves 52 and 53 are not provided in the vibrating arm 5.
In the vibrating arm 5, the grooves 52 and 53 are formed so as to be positioned between the side surfaces 513 and 514. For this reason, since a heat transfer path for balancing a difference in temperature between the side surfaces 513 and 514, which is caused when the vibrating arm 5 bends and vibrates, is formed by heat conduction so as to bypass the grooves 52 and 53, the heat transfer path thus becomes longer than a straight-line distance (shortest distance) between the side surfaces 513 and 514. Therefore, the relaxation time τ becomes longer and the thermal relaxation frequency fm becomes lower, as compared with a case where the grooves 52 and 53 are not provided in the vibrating arm 5.
f>√{square root over (fm0fm1)} (2)
Further, it is possible to obtain a higher Q value when being limited to the relation of f/fm0>1.
Meanwhile, in
Here, since the materials (metal materials) of the first and second driving electrodes 84 and 85 have higher thermal conductivity than quartz crystal which is the material of the vibrating arms 5 and 6, heat conduction through the first driving electrode 84 is actively performed in the vibrating arm 5 and heat conduction through the second driving electrode 85 is actively performed in the vibrating arm 6. When such heat conduction through the first and second driving electrodes 84 and 85 is actively performed, the relaxation time τ is shortened. Consequently, as shown in
Next, vibration characteristics of the resonator element 2 will be described on the basis of simulation results.
In the resonator element 2a shown in
Consideration is given to simulating vibration characteristics of the resonator element 2 in a state in which the resonator element 2a is fixed to an object by the first and second fixation portions R1 and R2 by using a gold bump (having a Young's modulus of 70.0 [GPa], a Poisson's ratio of 0.44, a mass density of 19300 [kg/m3], a diameter of 80 μm, and a thickness of 20 μm). Meanwhile, the object having the same physical properties as the package 9 is used. Regarding elastic waves reaching an interface between the first and second fixation portions R1 and R2 and the object, assuming that the elastic waves transmitting the object leak as they are and are not returned and that energy loss corresponding to the leakage is vibration leakage, a Q value taking only the vibration leakage into consideration is calculated.
A graph Q1 shown in
In addition, the graph Q1 shown in
The graph Q1 shown in
According to the graph Q1, the QLeak value is highest in the case of the plot q1, the QLeak value is rapidly lowered as the holding position S5 becomes lower than that in the plot q1, and the QLeak value is gently lowered as the holding position S5 becomes higher than that in the plot q1.
From the results, it may be said that the resonator element 2a shown in
For this reason, when the fixed region R is disposed centering on this position, it is possible to particularly effectively reduce the reduction in the Q value due to the vibration leakage of the resonator element 2a. In addition, providing of the fixed region R between the centroid G and the base end X of the supporting arm 7a can make being affected by vibration occurring when the vibrating arms 5 and 6 bend and deform more difficult.
Incidentally, vibration characteristics of the resonator element 2 may be simulated in a state where the resonator element 2a is fixed to an object using a bismaleimide-based conductive adhesive member (having a Young's modulus of 3.4 [GPa], a Poisson's ratio of 0.33, amass density of 4070 [kg/m3], a diameter of 80 μm, and a thickness of 20 μm) in place of the above-described gold bump. Even in this case, it is possible to obtain the same effects as in the case where the above-described gold bump is used.
Next, a resonator according to a second embodiment of the invention will be described.
Hereinafter, the resonator according to the second embodiment will be described focusing on the differences from the first embodiment described above, and a description of the same matters will be omitted.
The resonator according to the second embodiment of the invention is the same as that of the first embodiment described above except that the configuration of a resonator element is different. Meanwhile, the same components as in the first embodiment described above are denoted by the same reference numerals.
As shown in
Also in the second embodiment, the same effects as in the first embodiment described above can be exhibited.
Next, a resonator according to a third embodiment of the invention will be described.
Hereinafter, the resonator according to the third embodiment will be described focusing on the differences from the first embodiment described above, and a description of the same matters will be omitted.
The resonator according to the third embodiment of the invention is the same as that of the first embodiment described above except that the configuration of a resonator element is different. Meanwhile, the same components as in the first embodiment described above are denoted by the same reference numerals.
As shown in
Also in the third embodiment, the same effects as in the first embodiment described above can be exhibited.
Next, a resonator according to a fourth embodiment of the invention will be described.
Hereinafter, the resonator according to the fourth embodiment will be described focusing on the differences from the first embodiment described above, and a description of the same matters will be omitted.
The resonator according to the fourth embodiment of the invention is the same as that of the first embodiment described above except that the configuration of a resonator element is different. Meanwhile, the same components as in the first embodiment described above are denoted by the same reference numerals.
As shown in
Here, similarly to the resonator element 2 of the first embodiment, the resonator element 2C is configured so as to vibrate in an X reverse phase mode in which vibrating arms 5 and 6 bend and vibrate by alternately repeating mutual approach and separation. In addition to the vibration mode, there are unnecessary vibration modes such as an X common mode in which the vibrating arms 5 and 6 bend and vibrate to the same side in the X-axis direction, a Z common mode in which the vibrating arms 5 and 6 bend and vibrate to the same side in the Z-axis direction, a Z reverse phase mode in which the vibrating arms 5 and 6 bend and vibrate to opposite sides of the Z-axis, a torsional common mode in which the vibrating arms 5 and 6 are twisted and vibrate in the same direction about the Y-axis, and a torsional reverse phase mode in which the vibrating arms 5 and 6 are twisted and vibrate in opposite directions about the Y-axis. When the resonator element 2C vibrates in the X reverse phase mode, the supporting arm 7C alternately vibrates in the +Y-axis direction and the −Y-axis direction, as described above. However, when the resonator element 2C has an asymmetrical shape and when the resonator element is combined with an unnecessary mode, the distal end of the supporting arm 7C involuntarily vibrates in the X-axis direction (in-plane direction) and the Z-axis direction (out-plane direction). For this reason, as in this embodiment, the fixed region R is provided on the base end side by avoiding the distal end of the supporting arm 7C, and thus it is possible to further reduce vibration leakage.
In this embodiment, as compared with the first embodiment, the mass increases due to the large length of the supporting arm 7C, and the supporting arm is not likely to vibrate to that extent. In addition, it is possible to provide the fixed region R in a place (the base end side of the supporting arm 7C) which is further spaced from the distal end of the supporting arm 7C. Thus, since the fixed region R is less likely to be affected by vibration of the vibrating arms 5 and 6 described above, it is possible to particularly effectively reduce vibration leakage as compared with the first embodiment.
Also in the fourth embodiment, the same effects as in the first embodiment described above can be exhibited.
In addition, vibration characteristics of the resonator element 2 described above will be described below on the basis of simulation results.
In the resonator element 2b shown in
Consideration is given to simulating vibration characteristics of the resonator element 2 in a state in which the resonator element 2b is fixed to an object by the first and second fixation portions R1 and R2 by using a gold bump (having a Young's modulus of 70.0 [GPa], a Poisson's ratio of 0.44, a mass density of 19300 [kg/m3], a diameter of 80 μm, and a thickness of 20 μm). Meanwhile, the object having the same physical properties as a package 9 is used.
A graph Q2 shown in
In addition, the graph Q2 shown in
The graph Q2 shown in
According to the graph Q2, the QLeak value is highest in the case of the plot q2, the QLeak value is rapidly lowered as the holding position S5 becomes lower than that in the plot q2, and the QLeak value is gently lowered as the holding position S5 becomes higher than that in the plot q2.
From the results, it may be said that the resonator element 2b shown in
For this reason, when the fixed region R is disposed centering on this position, it is possible to particularly effectively reduce the reduction in the Q value due to the vibration leakage of the resonator element 2b. In addition, providing of the fixed region R between the centroid G and the base end X of the supporting arm 7 can make being affected by vibration occurring when the vibrating arms 5 and 6 bend and deform more difficult.
In addition, as in the simulation results of this embodiment, it is possible to obtain a higher QLeak value when the position of the fixed region R is changed in a state where the distal end of the supporting arm 7b passes across the centroid G when seen in a plan view and the length L6 is made constant, with respect to when the length L6 is changed in a state where the separation distance A5 is made constant as shown in the first embodiment. For this reason, it is possible to particularly effectively reduce vibration leakage as compared with the first embodiment. It is considered that this is because, as compared with the first embodiment, the mass increases due to the large length of the supporting arm 7C, and the supporting arm 7C is not likely to vibrate to that extent.
Next, a resonator according to a fifth embodiment of the invention will be described.
Hereinafter, the resonator according to the fifth embodiment will be described focusing on the differences from the first embodiment described above, and a description of the same matters will be omitted.
The resonator according to the fifth embodiment of the invention is the same as that of the first embodiment described above except that the configuration of a resonator element is different. Meanwhile, the same components as in the first embodiment described above are denoted by the same reference numerals.
As shown in
Here, similarly to the resonator element 2 of the first embodiment described above, the resonator element 2D is configured so as to vibrate in an X reverse phase mode. However, a combination of the vibration mode and another unnecessary vibration mode leads to an imbalance in vibrating arms 5 and 6, and thus the distal end of the supporting arm 7D involuntarily vibrates in the X-axis direction and the Z-axis direction. For this reason, similarly to the fourth embodiment described above, also in this embodiment, the fixed region R is provided by avoiding the distal end of the supporting arm 7D, and thus it is possible to further reduce vibration leakage.
Similarly to the first embodiment described above, in the resonator element 2D, vibrations of the vibrating arms 5 and 6 are offset by a width-decreasing portion 42, and thus are not likely to be transmitted to the supporting arm 7D. However, the vibration that cannot be wholly offset by the width-decreasing portion 42 may be transmitted to the supporting arm 7D through a base portion 4. For this reason, in this embodiment, the fixed region R is provided by avoiding the base end of the supporting arm 7D. Thus, it is possible to further reduce vibration leakage.
Meanwhile, a length L5 of the fixed region R is not particularly limited. However, when a separation distance (length in the Y-axis direction) between the centroid G and a base end (boundary) X of the supporting arm 7D is set to L10, it is preferable that the relation of 0.589×L10≦L5≦L10 is satisfied. Thus, it is possible to more reliably reduce a reduction in a Q value due to vibration leakage.
Also in the fifth embodiment, the same effects as in the first embodiment described above can be exhibited.
Next, a resonator according to a sixth embodiment of the invention will be described.
Hereinafter, the resonator according to the sixth embodiment will be described focusing on the differences from the first embodiment described above, and a description of the same matters will be omitted.
The resonator according to the sixth embodiment of the invention is the same as that of the first embodiment described above except that the configuration of a resonator element is different. Meanwhile, the same components as in the first embodiment described above are denoted by the same reference numerals.
As shown in
In addition, the base end side of the first fixation portion R1 is positioned at a base portion 4 across the base end of the supporting arm 7E when seen in a plan view from the Z-axis direction. That is, the first fixation portion R1 is provided over a boundary between the supporting arm 7E and the base portion 4. Here, in this embodiment, the base end of the supporting arm 7E, that is, a boundary between the supporting arm 7E and the base portion 4 is set to a line segment that connects places where both side surfaces of the supporting arm 7E are connected to the base portion 4, and is shown by a dashed line X in
Here, similarly to the resonator element 2 of the first embodiment described above, the resonator element 2E is configured so as to vibrate in an X reverse phase mode. However, a combination of the vibration mode and another unnecessary vibration mode leads to an imbalance in vibrating arms 5 and 6, and thus the distal end of the supporting arm 7E involuntarily vibrates in the X-axis direction and the Z-axis direction. For this reason, similarly to the fourth embodiment described above, also in this embodiment, the fixed region R is provided by avoiding the distal end of the supporting arm 7E. Thus, it is possible to further reduce vibration leakage.
Also in the sixth embodiment, the same effects as in the first embodiment described above can be exhibited.
Next, a resonator according to a seventh embodiment of the invention will be described.
Hereinafter, the resonator according to the seventh embodiment will be described focusing on the differences from the first embodiment described above, and a description of the same matters will be omitted.
The resonator according to the seventh embodiment of the invention is the same as that of the first embodiment described above except that the configuration of a resonator element is different. Meanwhile, the same components as in the first embodiment described above are denoted by the same reference numerals.
As shown in
In addition, a width W5 of the narrow width portion 71 is not particularly limited, but it is preferable that the width is equal to or greater than 20% and is equal to or less than 50% of a width W4 of a portion on the distal end side with respect to the narrow width portion. Thus, the above-described effects are further improved, and a vibration of a base portion 4 is not likely to be transmitted by the supporting arm 7F.
Also in the seventh embodiment, the same effects as in the first embodiment described above can be exhibited.
Next, a resonator according to an eighth embodiment of the invention will be described.
Hereinafter, the resonator according to the eighth embodiment will be described focusing on the differences from the first embodiment described above, and a description of the same matters will be omitted.
The resonator according to the eighth embodiment of the invention is the same as that of the first embodiment described above except that the configuration of a resonator element is different. Meanwhile, the same components as in the first embodiment described above are denoted by the same reference numerals.
As shown in
Also in the eighth embodiment, the same effects as in the first embodiment described above can be exhibited.
Meanwhile, in the above-described embodiments and modified examples, quartz crystal is used as the material of the resonator element. However, the invention is not limited thereto, and it is possible to use, for example, an oxide substrate such as aluminum nitride (AlN), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), lead zirconate titanate (PZT), lithium tetraborate (Li2B4O7), or langasite (La3Ga5SiO14), a laminated piezoelectric substrate configured by laminating a piezoelectric material such as aluminum nitride, tantalum pentoxide (Ta2O5), and the like on a glass substrate, piezoelectric ceramics, and the like.
In addition, it is possible to form a resonator element using a material other than a piezoelectric material. For example, it is also possible to form a resonator element using a silicon semiconductor material. In addition, a vibration (driving) method of the resonator element is not limited to a piezoelectric driving method. It is also possible to exhibit the configuration of the invention and the effects thereof in resonator elements such as an electrostatic driving type using an electrostatic force and a Lorentz driving type using a magnetic force, in addition to a piezoelectric driving type using a piezoelectric substrate. In addition, the terms used in the specification or the drawings at least once together with a different term having a broader or similar meaning can be replaced with a different term in any portion of the specification or the drawings.
Next, an oscillator to which the resonator element according to the invention (oscillator according to the invention) is applied will be described.
An oscillator 100 shown in
As shown in
Next, an electronic device to which the resonator element according to the invention is applied (electronic device according to the invention) will be described.
A display portion is provided on the back of a case (body) 1302 in the digital still camera 1300, so that display based on the imaging signal of the CCD is performed. The display portion functions as a viewfinder that displays a subject as an electronic image. In addition, a light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided on the front side (back side in
When a photographer checks a subject image displayed on the display portion and presses a shutter button 1306, an imaging signal of the CCD at that point in time is transferred and stored in a memory 1308. In addition, in the digital still camera 1300, a video signal output terminal 1312 and an input/output terminal for data communication 1314 are provided on the side surface of the case 1302. In addition, as shown in
Meanwhile, the electronic device including the resonator element according to the invention can be applied not only to the personal computer (mobile personal computer) shown in
Next, a moving object to which the resonator element according to the invention (moving object according to the invention) is applied will be described.
While the resonator element, the resonator, the oscillator, the electronic device, and the moving object according to the invention have been described with reference to the illustrated embodiments, the invention is not limited thereto, and the configuration of each portion may be replaced with an arbitrary configuration having the same function. In addition, other arbitrary structures may be added to the invention. In addition, the embodiments described above may be appropriately combined.
In the resonator element, a width-decreasing portion having a base portion of which the width (length along an X-axis direction) gradually decreases in a +Y-axis direction may be provided on the distal end side (side opposite to the width-decreasing portion) of the base portion, apart from the above-described width-decreasing portion. By providing the width-decreasing portion, a vibration of a vibrating arm is mainly offset (reduced and absorbed) by the width-decreasing portion, but it is possible to further efficiently reduce and absorb a vibration that cannot be wholly offset by the width-decreasing portion.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-128014 | Jun 2013 | JP | national |
