Patent Publication Number: US-9893733-B2

Title: Oscillator, electronic apparatus, and moving object

Description:
This is a Continuation of U.S. application Ser. No. 14/575,256 filed on Dec. 18, 2014, which claims the benefit of priority of Japanese Patent Application No. 2013-265005 filed on Dec. 24, 2013. The disclosure of the prior applications is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to an oscillator, an electronic apparatus, and a moving object. 
     2. Related Art 
     Heretofore, as the size and thickness of electronic apparatuses have been reduced, oscillators including a vibrating device such as a quartz crystal resonator have been required to be further reduced in size and thickness. In addition, the power consumption of the oscillators has also been required to be reduced for achieving energy saving. Especially in an oven-controlled crystal oscillator (OCXO) having a structure in which the ambient temperature of a quartz crystal resonator is kept constant by heating a heating element for avoiding the influence of ambient temperature to provide high frequency stability, heat from the heating element is not uniformly conducted to an entire substrate, and it is difficult to control the temperature of a component for oscillation arranged around the quartz crystal resonator. Therefore, the OCXO has a problem of failing to obtain high frequency stability. For solving such a problem, JP-A-2010-213280 discloses an OCXO in which a quartz crystal resonator element is arranged on an integrated circuit having a heating element and an oscillation circuit arranged on one semiconductor substrate and is arranged in a package together with other circuit elements. 
     However, in the case where the circuit element is built into the package for adjusting a resonator element, a circuit for oscillation, or the like as in the OCXO described above, when a circuit element or the like using resin is used as a constituent member for example, frequency characteristics of the resonator element may be varied due to a gas generated by the resin as a constituent member, or a gas generated from solder, a conductive adhesive, or the like as a member for connecting the circuit element with the package. 
     Moreover, since the heating element and the circuit for oscillation are arranged on one semiconductor substrate, it is necessary to raise the temperature of the heating element to a heating temperature or higher of the quartz crystal resonating element for heating the quartz crystal resonating element to a required temperature. However, since the heat of the heating element is easily conducted to the circuit for oscillation arranged on the same semiconductor substrate, the circuit for oscillation may be overheated, and thus the performance of the circuit for oscillation may be deteriorated. 
     SUMMARY 
     An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following modes or application examples. 
     APPLICATION EXAMPLE 1 
     This application example is directed to an oscillator including: an integrated circuit including a circuit for oscillation; a resonator element; a circuit element; a heating element; and a container, wherein the integrated circuit, the resonator element, and the heating element are arranged inside the container, and the circuit element is arranged outside the container. 
     According to this application example, the circuit element for adjusting the resonator element, the circuit for oscillation, or the like is arranged outside the container in which the integrated circuit, the resonator element, and the heating element are arranged. Therefore, a gas is not generated from a resin member constituting the circuit element, or solder, a conductive adhesive, or the like as a member for connecting the circuit element with the container, due to the heat of the heating element. Moreover, even if a gas is generated, the resonator element is not affected by the gas because the resonator element is accommodated in the container. Therefore, there is an advantageous effect in that stable frequency characteristics of the resonator element are maintained and thus the oscillator having high frequency stability can be obtained. Moreover, since the integrated circuit including the circuit for oscillation and the heating element are separated from each other, the integrated circuit is not overheated when heating the resonator element. Therefore, the resonator element can be stably oscillated, and thus the oscillator having high frequency stability can be obtained. 
     APPLICATION EXAMPLE 2 
     This application example is directed to the oscillator according to the application example described above, wherein the circuit element includes a quartz crystal resonator. 
     According to this application example, when a quartz crystal resonator is used as the circuit element, a feedback circuit of the circuit for oscillation is caused to have frequency selectivity to obtain a narrow-band negative resistance characteristic, and an unnecessary spurious negative resistance can be made small or positive. Therefore, unnecessary spurious oscillation can be suppressed. Therefore, there is an advantageous effect in that an unnecessary frequency is suppressed, the oscillator can be oscillated only in a primary vibration, and thus the oscillator having high frequency stability can be obtained. 
     APPLICATION EXAMPLE 3 
     This application example is directed to the oscillator according to the application example described above, wherein the circuit element includes an inductance element. 
     According to this application example, when an inductance element is used as the circuit element, an LC resonant circuit can be configured in combination with a capacitive element. By making the frequency of the LC resonant circuit coincident with the frequency of the primary vibration, a feedback circuit of the circuit for oscillation is caused to have frequency selectivity to obtain a narrow-band negative resistance characteristic, and an unnecessary spurious negative resistance can be made small or positive. Therefore, unnecessary spurious oscillation can be suppressed. Therefore, there is an advantageous effect in that an unnecessary frequency is controlled, the oscillator can be oscillated only in the primary vibration, and thus the oscillator having high frequency stability can be obtained. 
     APPLICATION EXAMPLE 4 
     This application example is directed to the oscillator according to the application example described above, wherein the resonator element is an SC-cut quartz crystal resonator element, and the circuit element is for attenuating an unnecessary frequency of frequency signals output from the circuit for oscillation. 
     According to this application example, an SC-cut quartz crystal resonator element is used as the resonator element, so that an oscillator having excellent frequency stability can be configured. Moreover, a secondary vibration mode, which is called a B mode and acts as a limiting factor for stable primary vibration called a C mode occurring in the oscillation of the SC-cut quartz crystal resonator element, is controlled by the circuit element such as a quartz crystal resonator or an inductance element, so that there is an advantageous effect in that the oscillator having high frequency stability can be obtained. 
     APPLICATION EXAMPLE 5 
     This application example is directed to the oscillator according to the application example described above, wherein the circuit element is arranged on the container. 
     According to this application example, the circuit element is arranged on an outer surface of the container in which the heating element is arranged, so that the heat of the heating element can be conducted to the circuit element. Therefore, there is an advantageous effect in that characteristics of the circuit element can be held constant, the influence of external temperature change can be reduced, and thus the oscillator having high frequency stability can be obtained. 
     APPLICATION EXAMPLE 6 
     This application example is directed to the oscillator according to the application example described above, wherein the circuit element overlaps the heating element in a plan view. 
     According to this application example, the circuit element is arranged, on the outer surface of the container in which the heating element is arranged, in a region overlapping the heating element in the plan view, so that a distance from the heating element to the circuit element can be reduced, and further heat of the heating element can be conducted to the circuit element. Therefore, there is an advantageous effect in that the influence of external temperature change can be further reduced, and thus the oscillator having high frequency stability can be obtained. 
     APPLICATION EXAMPLE 7 
     This application example is directed to the oscillator according to the application example described above, wherein the integrated circuit and the heating element are spaced apart from each other, and the resonator element is arranged on the heating element. 
     According to this application example, since the integrated circuit and the heating element are arranged spaced apart from each other inside the container, the heat of the heating element heating the resonator element is not directly conducted to the integrated circuit. Therefore, it is possible to reduce the characteristic degradation of the circuit for oscillation included in the integrated circuit caused by overheating. Moreover, since the resonator element is arranged on the heating element, the heat of the heating element can be conducted to the resonator element without loss of the heat, and thus temperature control of the resonator element can be further stabilized at low power consumption. 
     APPLICATION EXAMPLE 8 
     This application example is directed to an electronic apparatus including the oscillator according to the application example described above. 
     According to this application example, there is an advantageous effect in that the electronic apparatus including the oscillator having high frequency stability can be obtained. 
     APPLICATION EXAMPLE 9 
     This application example is directed to a moving object including the oscillator according to the application example described above. 
     According to this application example, there is an advantageous effect in that the moving object including the oscillator having high frequency stability can be configured. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIGS. 1A and 1B  are schematic configuration diagrams of an oscillator according to a first embodiment of the invention, in which  FIG. 1A  is a plan view, and  FIG. 1B  is a cross-sectional view taken along the line A-A. 
         FIGS. 2A and 2B  are schematic configuration diagrams of a container constituting the oscillator according to the first embodiment of the invention, in which  FIG. 2A  is a plan view, and  FIG. 2B  is a cross-sectional view taken along the line B-B. 
         FIG. 3  is a circuit diagram showing a configuration of the oscillator according to the invention. 
         FIGS. 4A to 4C  are schematic plan views each showing a modified example of the oscillator according to the invention. 
         FIGS. 5A and 5B  are schematic configuration diagrams of an oscillator according to a second embodiment of the invention, in which  FIG. 5A  is a plan view, and  FIG. 5B  is a cross-sectional view taken along the line C-C. 
         FIGS. 6A and 6B  are schematic configuration diagrams of an oscillator according to a third embodiment of the invention, in which  FIG. 6A  is a plan view, and  FIG. 6B  is a cross-sectional view taken along the line D-D. 
         FIGS. 7A and 7B  are schematic configuration diagrams of an oscillator according to a fourth embodiment of the invention, in which  FIG. 7A  is a plan view, and  FIG. 7B  is a cross-sectional view taken along the line E-E. 
         FIGS. 8A and 8B  are schematic configuration diagrams of an oscillator according to a fifth embodiment of the invention, in which  FIG. 8A  is a plan view, and  FIG. 8B  is a cross-sectional view taken along the line F-F. 
         FIGS. 9A and 9B  are schematic diagrams each showing an electronic apparatus including the oscillator according to the invention, in which  FIG. 9A  is a perspective view showing a configuration of a mobile (or notebook) personal computer, and  FIG. 9B  is a perspective view showing a configuration of a mobile phone (including a PHS). 
         FIG. 10  is a perspective view showing a configuration of a digital camera as an electronic apparatus including the oscillator according to the invention. 
         FIG. 11  is a perspective view showing a configuration of an automobile as a moving object including the oscillator according to the invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, embodiments of the invention will be described in detail based on the drawings. 
     Oscillator 
     First Embodiment 
     As an example of an oscillator  1  according to a first embodiment of the invention, an oven-controlled crystal oscillator (OCXO) including an SC-cut quartz crystal resonator element having excellent frequency stability will be shown and described with reference to  FIGS. 1A to 2B . 
       FIGS. 1A and 1B  are schematic diagrams showing a structure of the oscillator  1  according to the first embodiment of the invention, in which  FIG. 1A  is a plan view, and  FIG. 1B  is a cross-sectional view taken along the line A-A shown in  FIG. 1A .  FIGS. 2A and 2B  are schematic configuration diagrams of a container  40  constituting the oscillator  1  according to the first embodiment of the invention, in which  FIG. 2A  is a plan view, and  FIG. 2B  is a cross-sectional view taken along the line B-B shown in  FIG. 2A . In  FIGS. 1A and 2A , the oscillator  1  and the container  40  in a state where a cover  64  and a lid member  44  are removed therefrom are shown for convenience of description of the inner configurations of the oscillator  1  and the container  40 . Moreover, for convenience of description, an X-axis, a Y-axis, and a Z-axis are shown as three axes orthogonal to each other in the drawings including those described later. Further, for convenience of description, in a plan view as viewed from the Y-axis direction, a surface in the positive Y-axis direction is referred to as an upper surface, and a surface in the negative Y-axis direction is referred to as a lower surface. A wiring pattern or electrode pads formed on an upper surface of a base substrate  62 , connection terminals formed on an outer surface of the container  40 , and a wiring pattern or electrode pads formed inside the container  40  are not shown in the drawings. 
     As shown in  FIGS. 1A and 1B , the oscillator  1  is configured to include an integrated circuit  10  including a circuit for oscillation, the container  40  accommodating a heating element  14  and a resonator element  12  as an SC-cut quartz crystal resonator element therein, and a circuit element  16  arranged on the upper surface of the base substrate  62  outside the container  40 . Moreover, on the upper surface of the base substrate  62  of the oscillator  1 , the container  40  is arranged separate from the base substrate  62  via lead frames  66 , and a plurality of circuit components  20 ,  22 , and  24  such as a capacitor or a resistor are arranged. Further, the container  40  and the circuit element  16  are covered with the cover  64 , and accommodated inside a container  60 . The inside of the container  60  is hermetically sealed in a reduced-pressure atmosphere such as vacuum, or an inert gas atmosphere such as nitrogen, argon, or helium. 
     The circuit element  16  for adjusting the resonator element  12 , the circuit for oscillation included in the integrated circuit  10 , or the like, and the circuit components  20 ,  22 , and  24  are arranged outside the container  40  in which the heating element  14  is accommodated. Therefore, a gas is not generated from a resin member constituting the circuit element  16 , or solder, a conductive adhesive, or the like as a member for connecting the circuit element  16  or the circuit components  20 ,  22 , and  24  with the container  40 , due to heat of the heating element  14 . Moreover, even if a gas is generated, the resonator element  12  is not affected by the gas because the resonator element  12  is accommodated in the container  40 . Therefore, stable frequency characteristics of the resonator element  12  are maintained, and thus the oscillator  1  having high frequency stability can be obtained. 
     As shown in  FIGS. 2A and 2B , the integrated circuit  10 , the heating element  14  such as a power transistor or a resistance heating element, and the resonator element  12  arranged on an upper surface of the heating element  14  are accommodated inside the container  40 . The inside of the container  40  is hermetically sealed in a reduced-pressure atmosphere such as vacuum, or an inert gas atmosphere such as nitrogen, argon, or helium. 
     The container  40  is composed of a package main body  42  and the lid member  44 . As shown in  FIG. 2B , the package main body  42  is formed by stacking a first substrate  46 , a second substrate  48 , a third substrate  50 , a fourth substrate  52 , and a fifth substrate  54 . The second substrate  48 , the third substrate  50 , the fourth substrate  52 , and the fifth substrate  54  are each a circular body with the central portion removed. A sealing member  56  such as a seal ring or low-melting-point glass is formed at the peripheral edge of an upper surface of the fifth substrate  54 . 
     The second substrate  48  and the third substrate  50  form a recess (cavity) to accommodate the integrated circuit  10 . The fourth substrate  52  and the fifth substrate  54  form a recess (cavity) to accommodate the heating element  14  and the resonator element  12 . 
     The integrated circuit  10  is bonded at a predetermined position on an upper surface of the first substrate  46  with a bonding member  36 . The integrated circuit  10  is electrically connected through bonding wires  30  to electrode pads (not shown) arranged on an upper surface of the second substrate  48 . 
     The heating element  14  is bonded at a predetermined position on an upper surface of the third substrate  50  with a bonding member  34 . Electrode pads  26  formed on the upper surface (active surface  15 ) of the heating element  14  are electrically connected through bonding wires  30  to electrode pads (not shown) arranged on an upper surface of the fourth substrate  52 . 
     Accordingly, since the integrated circuit  10  and the heating element  14  are arranged spaced apart from each other inside the container  40 , it is difficult for the heat of the heating element  14  heating the resonator element  12  to be directly conducted to the integrated circuit  10 . Therefore, it is possible to control the characteristic degradation of the circuit for oscillation included in the integrated circuit  10  caused by overheating. 
     The resonator element  12  as an SC-cut quartz crystal resonator element that exhibits the lowest external stress sensitivity among quartz crystal resonator elements and thus has excellent frequency stability is arranged on the active surface  15  of the heating element  14 . Moreover, the SC-cut quartz crystal resonator element (the resonator element  12 ) is bonded to the heating element  14  with the electrode pads  26  formed on the active surface  15  and electrode pads (not shown) formed on a lower surface of the resonator element  12  via a bonding member  32  such as a metal bump or a conductive adhesive therebetween. Excitation electrodes (not shown) formed on the upper and lower surfaces of the resonator element  12  are electrically connected respectively to the electrode pads (not shown) formed on the lower surface of the resonator element  12 . It is sufficient that the resonator element  12  and the heating element  14  are connected so as to allow heat generated by the heating element  14  to be conducted to the resonator element  12 . Therefore, for example, the resonator element  12  and the heating element  14  may be connected with a non-conductive bonding member, and the resonator element  12  and the heating element  14  or the package main body  42  may be electrically connected using a conductive member such as a bonding wire. 
     Accordingly, since the resonator element  12  is arranged on the heating element  14 , the heat of the heating element  14  can be conducted to the resonator element  12  without loss of the heat, and thus temperature control of the resonator element  12  can be further stabilized at low power consumption. 
     For the constituent material of the cover  64  of the container  60  and the lead frame  66 , a low-thermal-conductivity iron-based alloy, such as 42 Alloy (iron-nickel alloy) , plated with nickel is preferred. 
     Moreover, the base substrate  62  of the container  60  is formed of an insulative material such as glass epoxy resin or ceramics. Moreover, wiring provided in the base substrate  62  is formed by a method of etching a substrate with copper foil covered on its entire surface, or a method of screen printing a metal wiring material such as tungsten (W) or molybdenum (Mo) on a substrate, baking the material, and plating nickel (Ni), gold (Au), or the like thereon. 
     Further, although the embodiment has been described in which a rectangular SC-cut quartz crystal resonator element is used as the resonator element  12 , this is not restrictive. A circular SC-cut quartz crystal resonator element or a rectangular or circular AT-cut quartz crystal resonator element may be used. Alternatively, a tuning fork type quartz crystal resonator element, a surface acoustic wave resonator element, and other piezoelectric resonators, or a micro electro mechanical systems (MEMS) resonator element may be used. When the AT-cut quartz crystal resonator element is used, a B-mode suppression circuit is not required, and thus the size of the oscillator  1  is reduced. 
     Oscillation Circuit 
     Next, an oscillation circuit of the oscillator  1  according to the invention will be described with reference to  FIG. 3 . 
       FIG. 3  is a circuit diagram showing the configuration of the oscillator  1  according to the invention. 
     In the SC-cut quartz crystal resonator element having excellent frequency stability, other than a thickness-shear vibration mode (C mode) as a primary vibration, a thickness-twist vibration mode (B mode) and a thickness-longitudinal vibration mode (A mode) exist as vibration modes at higher frequencies than the frequency of the thickness-shear vibration mode. Therefore, vibrations in the B mode and the A mode other than the C mode serve as spurious components (unwanted vibration components) and cause various troubles when the oscillator is configured. Especially a frequency f 2  of the B mode next to the C mode as the primary vibration is only away from a frequency f 1  of the C mode by about 9 to 10% of the frequency f 1 , and in addition, some resonance levels of the B mode are equal to those of the C mode. Therefore, the vibrations in the B mode and the A mode cause a frequency jump in which the oscillation frequency changes from f 1  to f 2 . 
     As shown in  FIG. 3 , therefore, in the circuit for oscillation of the oscillator  1 , a collector of a transistor  70  is connected to a power supply Vc, one end of the resonator element  12  as the SC-cut quartz crystal resonator element is connected to a base, and the other end of the SC-cut quartz crystal resonator element (the resonator element  12 ) is grounded via a variable capacitor  76 . Then, a series circuit of dividing capacitors  72  and  74  is connected between the base of the transistor  70  and the ground, and the circuit element  16  as a quartz crystal resonator is inserted and connected between the emitter and the middle point (dividing point) of the series circuit of the dividing capacitors  72  and  74 . Resistors  78  and  80  are bleeder resistors. A resistor  82  is a feedback resistor (load resistor). Vo is an output terminal of the oscillator  1 . As the quartz crystal resonator (the circuit element  16 ), an AT-cut quartz crystal resonator element, for example, is used, and the series resonance frequency thereof is set so as to substantially coincide with the oscillation frequency of the primary vibration (the C mode). 
     By inserting the quartz crystal resonator (the circuit element  16 ) between the emitter of the transistor  70  and the middle point of the series circuit of the dividing capacitors  72  and  74 , a feedback circuit is caused to have frequency selectivity to obtain a narrow-band negative resistance characteristic. Therefore, a sufficiently large negative resistance is obtained at the frequency f 1  of the C mode as the primary vibration, while a small negative resistance or positive resistance is exhibited at the frequency f 2  of the B mode. As a result, the oscillator cannot oscillate at the frequency of the B mode. Therefore, the oscillator  1  can be oscillated only in the C mode as the primary vibration, and thus the oscillator  1  having high frequency stability can be obtained. 
     The embodiment has been described in which a quartz crystal resonator is used as the circuit element  16 . However, this is not restrictive, and an inductance element may be used. When an inductance element is used as the circuit element  16 , an LC resonant circuit can be configured in combination with a capacitive element. By making the frequency of the LC resonant circuit coincident with the frequency of the primary vibration, the feedback circuit of the circuit for oscillation is caused to have frequency selectivity to obtain a narrow-band negative resistance characteristic, and an unnecessary spurious negative resistance can be made small or positive. Therefore, unnecessary spurious oscillation can be suppressed. Therefore, an unnecessary frequency is controlled, the oscillator  1  can be oscillated only in the primary vibration, and thus the oscillator  1  having high frequency stability can be obtained. 
     MODIFIED EXAMPLE 
     Next, modified examples of the oscillator  1  according to the first embodiment of the invention in mounting of a resonator element will be described with reference to  FIGS. 4A to 4C . 
       FIGS. 4A to 4C  are schematic plan views each showing a modified example of the oscillator  1  according to the first embodiment of the invention in mounting of a resonator element.  FIGS. 4A to 4C  show a state where the lid member  44  (refer to  FIG. 2B ) is removed for convenience of description of the inner configuration of the container  40 . 
     Hereinafter, the modified examples in mounting of a resonator element will be described mainly on differences from the first embodiment described above, and similar matters will not be described. 
     In the modified example shown in  FIG. 4A , in electrode pads  26  and  26   a  formed on an active surface  15   a  of a heating element  14   a , the area of the electrode pad  26   a  arranged on a lower surface of a resonator element  12   a  is larger than that of the electrode pad  26 . Therefore, since the mounting area of the resonator element  12   a  can be made large, an impact due to dropping or vibration can be reduced, and thus the deterioration of vibration characteristics or the like can be prevented. Moreover, since the area for bonding the resonator element  12   a  with the heating element  14   a  is large, heat conduction is enhanced, and thus the oscillator  1  with low power consumption and having high frequency stability can be obtained. 
     In the modified example shown in  FIG. 4B , in electrode pads  26  and  26   b  formed on an active surface  15   b  of a heating element  14   b , the area of the electrode pad  26   b  arranged on a lower surface of a resonator element  12   b  is larger than that of the electrode pad  26 . Moreover, an electrode pad  28  is formed on an upper surface of the resonator element  12   b,  and electrically connected through a bonding wire  30  to the electrode pad  26  formed on the active surface  15   b  of the heating element  14   b . Since the resonator element  12   b  can be fixed at one point, mounting strain or thermal strain can be reduced, and thus more stable vibration characteristics can be obtained, compared to two-point fixation. Moreover, since the electrode pad  28  is formed on the upper surface of the resonator element  12   b  to thereby eliminate the need for an electrode pattern forming step for wiring an excitation electrode (not shown) formed on the upper surface of the resonator element  12   b  to a lower surface of the resonator element  12   b , the cost of the resonator element  12   b  can be reduced. 
     The modified example shown in  FIG. 4C  has a configuration in which one electrode pad  26   c  is formed on an active surface  15   c  of a heating element  14   c  similarly to the modified example shown in  FIG. 4B , and therefore equivalent advantageous effects can be obtained. Moreover, an electrode pad  28   c  is formed on an upper surface of a resonator element  12   c , and electrically connected through a bonding wire  30  to an electrode pad (not shown) formed on the upper surface of the fourth substrate  52 . Therefore, it is possible to prevent bonding failure due to a narrowed interval between the electrode pad  28   c  and the electrode pad  26  formed on the active surface  15   c  of the heating element  14   c  caused by a size reduction of the oscillator  1 . 
     Second Embodiment 
     Next, an oscillator  1   a  according to a second embodiment of the invention will be described with reference to  FIGS. 5A and 5B . 
       FIGS. 5A and 5B  are schematic configuration diagrams of the oscillator  1   a  according to the second embodiment of the invention, in which  FIG. 5A  is a plan view, and  FIG. 5B  is a cross-sectional view taken along the line C-C in  FIG. 5A . In  FIG. 5A , the oscillator  1   a  in a state where an upper portion of the cover  64  is removed is shown for convenience of description of the inner configuration of the oscillator  1   a.    
     Hereinafter, the second embodiment will be described mainly on differences from the first embodiment described above, and similar matters will not be described. 
     As shown in  FIGS. 5A and 5B , the oscillator  1   a  according to the second embodiment differs from the oscillator  1  according to the first embodiment in that the circuit element  16  is arranged on a lower surface of the container  40 . 
     With such a configuration, the heat of the heating element  14  can be conducted to the circuit element  16  through conduction via the package main body  42 . Therefore, the temperature of the circuit element  16  can be held constant, the influence of external temperature change can be reduced, and thus the oscillator  1   a  having high frequency stability can be obtained. 
     Third Embodiment 
     Next, an oscillator  1   b  according to a third embodiment of the invention will be described with reference to  FIGS. 6A and 6B . 
       FIGS. 6A and 6B  are schematic configuration diagrams of the oscillator  1   b  according to the third embodiment of the invention, in which  FIG. 6A  is a plan view, and  FIG. 6B  is a cross-sectional view taken along the line D-D in  FIG. 6A . In  FIG. 6A , the oscillator  1   b  in a state where the upper portion of the cover  64  is removed is shown for convenience of description of the inner configuration of the oscillator  1   b.    
     Hereinafter, the third embodiment will be described mainly on differences from the first embodiment described above, and similar matters will not be described. 
     As shown in  FIGS. 6A  and GB, the oscillator  1   b  according to the third embodiment differs from the oscillator  1  according to the first embodiment in that the circuit element  16  is arranged on the lower surface of the container  40  to overlap a region where the heating element  14  is arranged in a plan view. 
     With such a configuration, a distance from the heating element  14  to the circuit element  16  can be reduced in the package main body  42 , and the heat of the heating element  14  can be more efficiently conducted to the circuit element  16  through conduction via the package main body  42 . Therefore, the influence of external temperature change can be further reduced, and thus the oscillator  1   b  having high frequency stability can be obtained. 
     Fourth Embodiment 
     Next, an oscillator  1   c  according to a fourth embodiment of the invention will be described with reference to  FIGS. 7A and 7B . 
       FIGS. 7A and 7B  are schematic configuration diagrams of the oscillator  1   c  according to the fourth embodiment of the invention, in which  FIG. 7A  is a plan view, and  FIG. 7B  is a cross-sectional view taken along the line E-E in  FIG. 7A . In  FIG. 7A , the oscillator  1   c  in a state where the upper portion of the cover  64  is removed is shown for convenience of description of the inner configuration of the oscillator  1   c.    
     Hereinafter, the fourth embodiment will be described mainly on differences from the first embodiment described above, and similar matters will not be described. 
     As shown in  FIGS. 7A and 7B , the oscillator  1   c  according to the fourth embodiment differs from the oscillator  1  according to the first embodiment in that a spacer  38  is arranged on the upper surface of the third substrate  50  (refer to  FIG. 2B ) of the package main body  42  constituting the container  40 , and the heating element  14  to which the resonator element  12  is bonded is arranged on an upper surface of the spacer  38 . 
     With such a configuration, when the spacer  38  is formed of a low-thermal-conductivity material such as glass, the heat of the heating element  14  is conducted only to the resonator element  12 , and thus the temperature of the resonator element  12  can be more stably kept. Moreover, when the spacer  38  is formed of a high-thermal-conductivity material such as copper (Cu) , the heat of the heating element  14  can be conducted to the entire container  40 , and therefore the integrated circuit  10  or the circuit element  16  can be kept at a stable temperature. Therefore, the oscillator  1   c  having high frequency stability can be obtained. 
     Fifth Embodiment 
     Next, an oscillator  1   d  according to a fifth embodiment of the invention will be described with reference to  FIGS. 8A and 8B . 
       FIGS. 8A and 8B  are schematic configuration diagrams of the oscillator  1   d  according to the fifth embodiment of the invention, in which  FIG. 8A  is a plan view, and  FIG. 8B  is a cross-sectional view taken along the line F-F in  FIG. 8A . In  FIG. 8A , the oscillator  1   d  in a state where the upper portion of the cover  64  is removed is shown for convenience of description of the inner configuration of the oscillator  1   d.    
     Hereinafter, the fifth embodiment will be described mainly on differences from the first embodiment described above, and similar matters will not be described. 
     As shown in  FIGS. 8A and 8B , the oscillator  1   d  according to the fifth embodiment differs from the oscillator  1  according to the first embodiment in that the position of the heating element  14  arranged on the upper surface of the third substrate  50  (refer to  FIG. 2E ) of the package main body  42  constituting the container  40  is different, and a spacer  38   d  is arranged at a position facing the heating element  14  in a plan view. 
     With such a configuration, when the resonator element  12  is bonded to the upper surface of the heating element  14 , the inclining of the tip end (end in the positive X-axis direction) of the resonator element  12  can be reduced, and an impact due to dropping or vibration can be softened. Therefore, the oscillator  1   d  having excellent drop resistance or impact resistance can be obtained. 
     Electronic Apparatus 
     Next, electronic apparatuses to which the oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  according to one embodiment of the invention is applied will be described based on  FIGS. 9A to 10 . 
       FIGS. 9A and 9B  are schematic diagrams each showing an electronic apparatus including the oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  according to one embodiment of the invention, in which  FIG. 9A  is a perspective view showing a configuration of a mobile (or notebook) personal computer  1100 , and  FIG. 9B  is a perspective view showing a configuration of a mobile phone  1200  (including a PHS). 
     In  FIG. 9A , the personal computer  1100  is composed of a main body portion  1104  including a keyboard  1102  and a display unit  1106  including a display portion  1000 . The display unit  1106  is rotatably supported relative to the main body portion  1104  via a hinge structure portion. The oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  having high frequency stability is built into the personal computer  1100 . 
     In  FIG. 9B , the mobile phone  1200  includes a plurality of operation buttons  1202 , an earpiece  1204 , and a mouthpiece  1206 . The display portion  1000  is arranged between the operation buttons  1202  and the earpiece  1204 . The oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  having high frequency stability is built into the mobile phone  1200 . 
       FIG. 10  is a perspective view showing a configuration of a digital camera  1300  as an electronic apparatus including the oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  according to one embodiment of the invention. In  FIG. 10 , connections with external apparatuses are also shown in a simplified manner. 
     The digital camera  1300  photoelectrically converts an optical image of a subject with an imaging element such as a charge coupled device (CCD) to generate imaging signals (image signals). 
     The display portion  1000  is provided on a back surface of a case (body)  1302  in the digital camera  1300  and configured to perform display based on imaging signals generated by the CCD. The display portion  1000  functions as a finder that displays the subject as an electronic image. Moreover, on the front side (the rear side in the drawing) of the case  1302 , a light receiving unit  1304  including an optical lens (imaging optical system) and the CCD is provided. 
     When a photographer confirms the subject image displayed on the display portion  1000  and presses down a shutter button  1306 , imaging signals of the CCD at the time are transferred to and stored in a memory  1308 . Moreover, in the digital camera  1300 , a video signal output terminal  1312  and a data communication input/output terminal  1314  are provided on a side surface of the case  1302 . Then, as shown in the drawing, a television monitor  1330  and a personal computer  1340  are connected as necessary to the video signal output terminal  1312  and the data communication input/output terminal  1314 , respectively. Further, the imaging signals stored in the memory  1308  are output to the television monitor  1330  or the personal computer  1340  by a predetermined operation. The oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  having high frequency stability is built into the digital camera  1300 . 
     As described above, the oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  having high frequency stability is utilized, whereby a higher-performance electronic apparatus can be provided as an electronic apparatus. 
     In addition to the personal computer  1100  (mobile personal computer) in  FIG. 9A , the mobile phone  1200  in  FIG. 9B , and the digital camera  1300  in  FIG. 10 , the oscillator  1 ,  1   a ,  1   b ,  1   c , or  1   d  according to one embodiment of the invention can be applied to electronic apparatuses such as, for example, inkjet ejection apparatuses (for example, inkjet printers), laptop personal computers, television sets, video camcorders, car navigation systems, pagers, electronic notebooks (including those with communication function), electronic dictionaries, calculators, electronic gaming machines, workstations, videophones, surveillance television monitors, electronic binoculars, POS terminals, medical apparatuses (for example, electronic thermometers, sphygmomanometers, blood glucose meters, electrocardiogram measuring systems, ultrasonic diagnosis apparatuses, and electronic endoscopes), fishfinders, various types of measuring instrument, indicators (for example, indicators used in vehicles, aircraft, and ships), flight simulators, apparatuses for mobile communication base station, storage area network apparatuses such as routers or switches, local area network apparatuses, and network transmission apparatuses. 
     Moving Object 
     Next, a moving object to which the oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  according to one embodiment of the invention is applied will be described based on  FIG. 11 . 
       FIG. 11  is a perspective view showing a configuration of an automobile  1400  as a moving object including the oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  according to one embodiment of the invention. 
     In the automobile  1400 , a gyro sensor configured to include the oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  according to the invention is mounted. For example, as shown in  FIG. 11 , an electronic control unit  1402  into which the gyro sensor to control tires  1401  is built is mounted in the automobile  1400  as a moving object. Moreover, as other examples, the oscillator  1 ,  1   a ,  1   b ,  1   c , or  1   d  can be widely applied to electronic control units (ECUs) such as for keyless entry systems, immobilizers, car navigation systems, car air-conditioners, anti-lock brake systems (ABSs), air bags, tire pressure monitoring systems (TPMSs), engine control, battery monitors of hybrid and electric automobiles, and car body attitude control systems. 
     As described above, the oscillator  1 , the oscillator  1   a , the oscillator  1   b , the oscillator  1   c , or the oscillator  1   d  having high frequency stability is utilized, whereby a higher-performance moving object can be provided as a moving object. 
     Although the oscillators  1 ,  1   a ,  1   b ,  1   c , and  1   d , the electronic apparatuses, and the moving object according to the invention have been described above based on the embodiments shown in the drawings, the invention is not limited to the embodiments. The configuration of each part can be replaced with any configuration having a similar function. Moreover, any other configurations may be added to the invention. Moreover, the embodiments described above may be appropriately combined with each other. 
     The entire disclosure of Japanese Patent Application No. 2013-265005, filed Dec. 24, 2013 is expressly incorporated by reference herein.