Thermostatic oven type piezoelectric oscillator

Abstract

To provide a thermostatted piezoelectric oscillator capable of improving temperature controllability of a piezoelectric oscillator by a heater control region.SOLUTION: In an oven-controlled Xtal(crystal) oscillator (OCXO) 1, a crystal oscillator 50 is hermetically sealed inside a package 2 for heat insulation. The OCXO comprises an oscillation IC 51 for supplying a voltage to the crystal oscillator 50 and controlling the piezoelectric oscillation of the crystal oscillator 50, and a heater IC 52 for supplying a current to a heating element 52a and controlling the temperature of the crystal oscillator 50 to be substantially constant, and a voltage regulator 51b for controlling the voltage supplied to the crystal oscillator 50 is not provided in the oscillation IC 51, but is provided in the heater IC 52.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an oven-controlled piezoelectric oscillator. [Background technology]

[0002] The vibration frequency of a piezoelectric vibrator such as a quartz crystal vibrator changes according to temperature based on its inherent frequency-temperature characteristics. Therefore, in order to keep the temperature around the piezoelectric vibrator constant, an oven-controlled piezoelectric oscillator (hereinafter also referred to as "OCXO") is known in which the piezoelectric vibrator is enclosed in a thermostatic oven (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-205093 A [Patent Document 2] JP 2018-14705 A Summary of the Invention [Problem to be solved by the invention]

[0004] The OCXO described above includes an oscillation control area (e.g., an oscillation IC) for supplying a voltage to the piezoelectric vibrator and controlling the piezoelectric vibration of the piezoelectric vibrator, and a heater control area (e.g., a heater IC) for supplying a current to the heating element and controlling the temperature of the piezoelectric vibrator to be approximately constant. However, if a voltage regulator that controls the voltage supplied to the piezoelectric vibrator is provided in the oscillation control area, the following problems may occur.

[0005] The size of the oscillation control region increases by the amount of the voltage regulator provided, making it difficult to miniaturize the piezoelectric oscillator consisting of the oscillation control region and the piezoelectric vibrator provided integrally therewith. This increases the thermal capacity of the piezoelectric oscillator, reducing the temperature controllability of the piezoelectric oscillator by the heater control region. Furthermore, in order to increase the current flowing through the voltage regulator to suppress noise from the voltage regulator, it is necessary to increase the size of the voltage regulator, making it even more difficult to miniaturize the piezoelectric oscillator. Furthermore, increasing the current of the voltage regulator increases the temperature of the oscillation control region, reducing the temperature controllability of the piezoelectric oscillator by the heater control region.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide an oven-controlled piezoelectric oscillator that enables improved temperature controllability of the piezoelectric oscillator using a heater control region. [Means for solving the problem]

[0007] The present invention provides a means for solving the above-mentioned problems as follows: That is, the present invention provides an oven-controlled piezoelectric oscillator in which a piezoelectric vibrator is sealed inside a heat-insulating package, the oven-controlled piezoelectric oscillator includes an oscillation control region for supplying a voltage to the piezoelectric vibrator and controlling the piezoelectric vibration of the piezoelectric vibrator, and a heater control region for supplying a current to a heating element and controlling the temperature of the piezoelectric vibrator to be substantially constant, and a voltage regulator for controlling the voltage supplied to the piezoelectric vibrator is not provided in the oscillation control region but is provided in the heater control region. The oscillation control area is provided in an oscillation IC, the heater control area is provided in a heater IC, and the voltage regulator is provided in the heater IC. It is characterized by:

[0008] According to the above configuration, the voltage regulator can be removed from the oscillation control region, and the oscillation control region can be made smaller. This allows the thermal capacity of the piezoelectric oscillator consisting of the oscillation control region and the piezoelectric vibrator integrally provided therewith to be reduced. As a result, temperature control with low power becomes easier, and the temperature controllability of the piezoelectric oscillator by the heater control region can be improved. In addition, regardless of the size of the piezoelectric vibrator, a design can be made in which the size of the voltage regulator is increased to increase the current supplied to the voltage regulator, which contributes to improving noise characteristics. In this case, even if the current of the voltage regulator is increased, the temperature of the oscillation control region does not increase, and therefore the temperature controllability of the piezoelectric oscillator by the heater control region is not reduced.

[0009] Also, The oscillation control area is provided in an oscillation IC, the heater control area is provided in a heater IC, and the voltage regulator is provided in the heater IC. So, The voltage regulator can be removed from the oscillation IC, which allows the oscillation IC to be made smaller. This allows the piezoelectric vibrator on which the oscillation IC is mounted to be made smaller, and the heat capacity of the piezoelectric oscillator can be reduced. As a result, temperature control with low power becomes easier, and the temperature controllability of the piezoelectric oscillator by the heater IC can be improved. In addition, regardless of the size of the piezoelectric vibrator, a design can be made in which the size of the voltage regulator is increased to increase the current supplied to the voltage regulator, which contributes to improving noise characteristics. In this case, even if the current of the voltage regulator is increased, the temperature of the oscillation IC does not rise, so there is no decrease in the temperature controllability of the piezoelectric oscillator by the heater IC.

[0010] In the above configuration, it is preferable that the voltage regulator provided in the heater IC is electrically connected to the oscillation IC by a single wiring. According to this configuration, the voltage regulator provided in the heater IC and the oscillation IC are thermally connected directly without passing through other intermediate objects such as the packaging material of the piezoelectric vibrator, so that the heat of the heater IC and the oscillation IC does not transfer to other places through the wiring. This makes it possible to minimize the temperature difference between the piezoelectric vibrator and the oscillation IC, and improve the temperature controllability of the piezoelectric oscillator by the heater IC.

[0011] The present invention also provides an oven-controlled piezoelectric oscillator in which a piezoelectric vibrator is sealed inside a heat-insulating package, the oven-controlled piezoelectric oscillator comprising an oscillation control region for supplying a voltage to the piezoelectric vibrator and controlling the piezoelectric vibration of the piezoelectric vibrator, and a heater control region for supplying a current to a heating element and controlling the temperature of the piezoelectric vibrator to be substantially constant, the oscillation control region not being provided with a voltage regulator for controlling the voltage supplied to the piezoelectric vibrator, but being provided with the heater control region; A noise absorbing capacitor of the voltage regulator is accommodated in a space different from the space accommodating the piezoelectric vibrator in the package. It is characterized by: In detail, the package preferably has a base with an H-shaped cross section having a first recess with an opening at the top and a second recess with an opening at the bottom, and at least the piezoelectric vibrator and the heating element are housed in the first recess, and the noise absorbing capacitor is housed in the second recess. With these configurations, for example, it is not necessary to provide a space for mounting the noise absorbing capacitor in an insulating substrate (core substrate) in which at least the piezoelectric vibrator and the heating element are housed in the first recess. This makes it possible to reduce the size of the insulating substrate, reduce the heat capacity of the insulating substrate, and improve the temperature controllability of the piezoelectric oscillator by the heater IC. Effect of the Invention

[0012] According to the present invention, the voltage regulator can be removed from the oscillation control region, and the oscillation control region can be made smaller. This reduces the heat capacity of the piezoelectric oscillator consisting of the oscillation control region and the piezoelectric vibrator integrally provided therewith, and improves the temperature controllability of the piezoelectric oscillator by the heater control region. In addition, regardless of the size of the piezoelectric vibrator, a design is possible in which the size of the voltage regulator is increased to increase the current supplied to the voltage regulator, which contributes to improving noise characteristics. In this case, even if the current of the voltage regulator is increased, the temperature of the oscillation control region does not increase, and therefore the temperature controllability of the piezoelectric oscillator by the heater control region is not reduced. [Brief description of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of an OCXO according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view of the OCXO of FIG. [Diagram 3] 2 is a cross-sectional view showing a crystal oscillator included in the core portion of the OCXO of FIG. 1. [Figure 4] 2 is a plan view showing a crystal oscillator included in the core portion of the OCXO of FIG. 1. [Diagram 5] 2 is a circuit diagram showing a schematic configuration of an oscillation IC and a heater IC of the OCXO shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] As shown in FIG. 1, the OCXO 1 according to this embodiment has a structure in which a core part 5 is disposed inside a package 2 made of ceramic or the like, and is hermetically sealed by a lid (cover) 3. In detail, the package 2 has a base with an H-shaped cross section having a first recess 2a with an opening at the top and a second recess 2e with an opening at the bottom. The core part 5 is sealed in an airtight state inside the first recess 2a. The lid 3 is fixed to the upper surface of the peripheral wall part 2b surrounding the first recess 2a by seam welding via a sealing material 8, and the inside of the first recess 2a of the package 2 is sealed (airtight). As the sealing material 8, for example, a metal-based sealing material such as an Au-Su alloy or solder is preferably used, but a sealing material such as a low-melting point glass may also be used. In addition, it is possible to adopt a configuration of a sealing member by a method such as seam sealing using a metal ring, direct seam sealing without using a metal ring, beam sealing, etc. (seam sealing is preferable in order not to reduce the degree of vacuum). The internal space of the first recess 2a of the package 2 is preferably a vacuum (for example, a degree of vacuum of 10 Pa or less) or an atmosphere with low thermal conductivity such as low-pressure nitrogen or argon. Note that Fig. 2 shows the OCXO 1 with the lid 3 removed, and illustrates the internal structure of the OCXO 1.

[0016] A step portion 2c is formed on the inner wall surface of the peripheral wall portion 2b of the package 2 along the arrangement of the connection terminals (not shown). The core portion 5 is disposed on the bottom surface of the first recess 2a between a pair of opposing step portions 2c, 2c via a plate-shaped core substrate 4. Alternatively, the step portion 2c may be formed so as to surround the bottom surface of the first recess 2a on all four sides. The core substrate 4 is bonded to the bottom surface of the first recess 2a by a non-conductive adhesive 7, and a space 2d is formed in the lower portion of the core substrate 4. In addition, the external terminals (not shown) formed on each component of the core portion 5 are connected by wire bonding to the connection terminals formed on the step surface of the step portion 2c via the wires 6a, 6b. In addition, the external terminals (not shown) formed on the oscillation IC 51 of the core portion 5 and the external terminals (not shown) formed on the heater IC 52 are connected by wire bonding via the wires 6c. The non-conductive adhesives 7, 7 are disposed at both longitudinal ends of the core substrate 4, and are linearly disposed along the lateral direction of the core substrate 4 (the direction perpendicular to the paper surface of FIG. 1). In this manner, by mounting the core portion 5 on the package 2 using the core substrate 4 and forming a space 2d below the core substrate 4, it is possible to improve the heat insulating effect for the core portion 5. Furthermore, by providing a pair of stepped portions 2c on the package 2 and providing connection terminals on the stepped portions 2c, the connection terminals are brought closer to the opening of the package 2, making it easier to perform wire bonding between the core portion 5 and the package 2.

[0017] A plurality of capacitors 9 (three in FIG. 1) are housed inside the second recess 2e of the package 2. The capacitors 9 are provided as capacitors for absorbing noise from a voltage regulator 51b, which will be described later. The capacitors 9 are mounted on the bottom surface of the second recess 2e by solder. In this way, by arranging the capacitors 9 in the second recess 2e, which is different from the first recess 2a in which the core unit 5 is arranged, it is possible to prevent the degree of vacuum in the sealed space in which the core unit 5 is arranged from being reduced by gas generated from the solder. This makes it possible to maintain good thermal insulation of the OCXO 1. In addition, by arranging the capacitors 9 outside the sealed space in which the core unit 5 is arranged, it is possible to reduce the heat capacity of this sealed space, and by reducing the heat capacity of the sealed space, it is possible to achieve temperature control at low power and improvement of the temperature tracking ability of the core unit 5.

[0018] Next, the core section 5 will be described. The core section 5 is a package of various electronic components used in the OCXO1, and has a three-layer structure (laminated structure) in which an oscillation IC 51, a crystal oscillator (piezoelectric oscillator) 50, and a heater IC 52 are laminated in this order from the top. The areas of the oscillation IC 51, the crystal oscillator 50, and the heater IC 52 in a plan view are gradually reduced toward the top. The core section 5 is configured to stabilize the oscillation frequency of the OCXO1 by adjusting the temperatures of the crystal oscillator 50, the oscillation IC 51, and the heater IC 52, which have particularly large temperature characteristics. Note that the various electronic components in the core section 5 are not sealed with sealing resin, but may be sealed with sealing resin depending on the sealing atmosphere.

[0019] The crystal oscillator 100 is configured by the crystal unit 50 and the oscillation IC 51. The oscillation IC 51 is mounted on the crystal unit 50 via a plurality of metal bumps 51a. As shown in FIG. 5, the oscillation IC 51 includes a level shifter 51c, a frequency divider 52d, and an output buffer 52e. A voltage regulated by a voltage regulator 51b built in the heater IC 52 is supplied to the oscillation IC 51 via a wire 6c, and applied to an excitation electrode of the vibration part of the crystal unit 50. The oscillation IC 51 controls the piezoelectric vibration of the crystal unit 50, thereby controlling the oscillation frequency of the OCXO 1. An underfill may be interposed between the opposing surfaces of the crystal unit 50 and the oscillation IC 51.

[0020] As shown in FIG. 5, the heater IC 52 includes a heating element (heater) 52a, a control circuit (current control circuit) 52c for controlling the temperature of the heating element 52a, and a temperature sensor 52b for detecting the temperature of the heating element 52a. The control circuit 52c controls the amount of current supplied from an external power source to the heating element 52a. The heating element 52a generates heat according to the amount of current supplied, and heats the core unit 5. By controlling the temperature of the core unit 5 using the heater IC 52, the temperature of the crystal unit 50 is maintained at a substantially constant temperature, and the oscillation frequency of the OCXO 1 is stabilized. In this embodiment, the heater IC 52 includes a built-in voltage regulator 51b for controlling the voltage supplied to the crystal unit 50. The voltage regulator 51b adjusts the voltage supplied from the external power source and supplies it to the oscillation IC 51.

[0021] A non-conductive adhesive 54 is interposed between the opposing surfaces of the crystal unit 50 and the heater IC 52, and the opposing surfaces of the crystal unit 50 and the heater IC 52 are fixed together by the non-conductive adhesive 54. In this case, the bottom surface of the crystal unit 50 and the top surface of the heater IC 52 are joined together via the non-conductive adhesive 54.

[0022] A non-conductive adhesive 55 is interposed between the opposing surfaces of the heater IC 52 and the core substrate 4, and the opposing surfaces of the heater IC 52 and the core substrate 4 are fixed to each other by the non-conductive adhesive 55. As the non-conductive adhesives 54 and 55, for example, a polyimide adhesive, an epoxy adhesive, or the like is used.

[0023] In the core unit 5, external terminals for wire bonding are formed on the upper surfaces of the crystal unit 50 and the heater IC 52. The wire bonding of the crystal unit 50 and the heater IC 52 is not performed before the core unit 5 is mounted on the package 2, but is performed after the core unit 5 is mounted on the package 2. That is, as shown in FIG. 1, after the core unit 5 is mounted on the package 2, the external terminal formed on the upper surface of the crystal unit 50 is connected to the connection terminal formed on the step surface of the step portion 2c via the wire 6a. Also, the external terminal formed on the upper surface of the heater IC 52 is connected to the connection terminal formed on the step surface of the step portion 2c via the wire 6b. In this way, by performing wire bonding after the core unit 5 is mounted on the package 2, the wire bonding can be performed efficiently.

[0024] Although the type of crystal unit 50 used in the core portion 5 is not particularly limited, a sandwich-structured device that is easy to make thin can be preferably used. A sandwich-structured device is a three-layered device that is composed of first and second sealing members made of glass or crystal, and a piezoelectric diaphragm made of, for example, crystal and having a vibration part with excitation electrodes formed on both main surfaces, in which the first and second sealing members are laminated and bonded via the piezoelectric diaphragm, and the vibration part of the piezoelectric diaphragm arranged inside is hermetically sealed.

[0025] An example of a crystal oscillator 100 in which such a sandwich-structured crystal resonator 50 and an oscillation IC 51 are integrally provided will be described with reference to Figures 3 and 4. Figure 3 is a cross-sectional view (cross-sectional view taken along line AA in Figure 4) of the crystal oscillator 100, and Figure 4 is a plan view of the crystal oscillator 100. Note that since the sandwich-structured crystal resonator itself is well known, a detailed description of the internal structure of the crystal resonator 50 will be omitted.

[0026] As shown in Fig. 3, the crystal oscillator 100 is configured to include a crystal vibration plate (piezoelectric vibration plate) 10, a first sealing member 20, a second sealing member 30, and an oscillation IC 51. In this crystal oscillator 100, the crystal vibration plate 10 and the first sealing member 20 are joined by an annular sealing joint 41, and the crystal vibration plate 10 and the second sealing member 30 are joined by an annular sealing joint 42, thereby forming a package with a substantially rectangular sandwich structure. The sealing joints 41 and 42 can be formed, for example, on the respective bonding surfaces of the crystal vibration plate 10, the first sealing member 20, and the second sealing member 30, with a bonding pattern (for example, a bonding pattern in which a Ti layer and an Au layer are formed from the bottom layer side) having an Au layer on the surface, and bonding is performed by Au-Au diffusion bonding when the bonding surfaces are attached to each other. According to this configuration, the gap dimension between the quartz crystal plate 10 and each of the sealing members 20, 30 can be made extremely small, at about 0.15 μm to 1 μm, which is advantageous for making the core portion 5 thinner and reducing its heat capacity.

[0027] That is, in the crystal oscillator 100, a first sealing member 20 and a second sealing member 30 are bonded to both main surfaces of the crystal vibration plate 10 on which the vibration part (not shown) is formed, thereby forming an internal space (cavity) of the package, and the vibration part of the crystal vibration plate 10 is hermetically sealed in this internal space. The oscillation IC 51 mounted on the first sealing member 20 is a one-chip integrated circuit element that constitutes an oscillation circuit together with the crystal vibration plate 10.

[0028] As shown in Fig. 4, the connection terminal 21 and the external terminal 22 are formed on the top surface of the crystal unit 50. One end (end on the outer periphery side) of the connection terminal 21 is electrically connected to the excitation electrode of the vibrating unit (via wiring or through holes in the crystal unit 50), and the other end (end on the inner periphery side) is connected to the oscillation IC 51 via metal bump 51a. One end (end on the outer periphery side) of the external terminal 22 is used for wire bonding with the package 2, and the other end (end on the inner periphery side) is connected to the oscillation IC 51 via metal bump 51a. The oscillation IC 51 is connected to the connection terminal 21 and the external terminal 22 by the FCB method using the metal bump 51a.

[0029] In this embodiment, the OCXO1 includes an oscillation control region for supplying a voltage to the crystal oscillator 50 and controlling the piezoelectric oscillation of the crystal oscillator 50, and a heater control region for supplying a current to a heating element (heater) 52a and controlling the temperature of the crystal oscillator 50 to be substantially constant, and a voltage regulator 51b for controlling the voltage supplied to the crystal oscillator 50 is provided in the heater control region, not in the oscillation control region. Specifically, the oscillation control region is provided in the oscillation IC 51, the heater control region is provided in the heater IC 52, and the voltage regulator 51b is provided in the heater IC 52.

[0030] According to this embodiment, the voltage regulator 51b that controls the voltage supplied to the crystal resonator 50 is provided in the heater IC 52, not in the oscillation IC 51, so that the voltage regulator 51b can be eliminated from the oscillation IC 51, and the oscillation IC 51 can be made smaller. This allows the crystal resonator 50 on which the oscillation IC 51 is mounted to be made smaller, and the heat capacity of the crystal oscillator 100 can be reduced. As a result, temperature control with low power becomes easier, and the temperature controllability of the crystal oscillator 100 by the heater IC 52 can be improved.

[0031] Furthermore, it is possible to design the voltage regulator 51b to be larger in size and to increase the current supplied to the voltage regulator 51b, contributing to improved noise characteristics, regardless of the size of the crystal resonator 50. In this case, even if the current of the voltage regulator 51b is increased, the temperature of the oscillation IC 51 does not increase, so there is no decrease in the temperature controllability of the crystal oscillator 100 by the heater IC 52.

[0032] In this embodiment, the voltage regulator 51b provided in the heater IC 52 is electrically connected to the oscillation IC 51 by a single wire 6c. In this way, the voltage regulator 51b provided in the heater IC 52 and the oscillation IC 51 are thermally connected directly without passing through other intermediate objects such as the packaging members (first and second sealing members 20 and 30) of the crystal unit 50, so that the heat of the heater IC 52 and the oscillation IC 51 does not move to other places through the wire 6c. This makes it possible to minimize the temperature difference between the crystal unit 50 and the oscillation IC 51, thereby improving the temperature controllability of the crystal oscillator 100 by the heater IC 52.

[0033] In this embodiment, the package 2 is formed with an H-shaped cross section, at least the crystal unit 50 and the heating element 52a are accommodated in the first recess 2a of the package 2, and the capacitor 9 for absorbing noise of the voltage regulator 51b is accommodated in the second recess 2e of the package 2. In this way, the capacitor 9 is accommodated in a space different from the space accommodating the crystal unit 50 and the like of the package 2. Therefore, it is not necessary to provide a space for mounting the capacitor 9 in the core substrate 4 in which at least the crystal unit 50 and the heating element 52a are accommodated in the first recess 2a via the core substrate 4. This allows the core substrate 4 to be miniaturized, the heat capacity of the core substrate 4 to be reduced, and the temperature controllability of the crystal oscillator 100 by the heater IC 52 to be improved.

[0034] The present invention can be embodied in various other forms without departing from its spirit, essence, or main features. Therefore, the above-described embodiments are merely illustrative in all respects and should not be interpreted as being limited. The scope of the present invention is defined by the claims, and is not limited in any way by the text of the specification. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present invention.

[0035] In the above embodiment, the oscillation IC 51 for supplying a voltage to the crystal unit 50 and controlling the piezoelectric vibration of the crystal unit 50 and the heater IC 52 for supplying a current to the heating element (heater) 52a and controlling the temperature of the crystal unit 50 to be approximately constant are separate components. That is, the oscillation IC 51 is an oscillation control region for supplying a voltage to the crystal unit 50 and controlling the piezoelectric vibration of the crystal unit 50, and the heater IC 52 is a heater control region for supplying a current to the heating element 52a and controlling the temperature of the crystal unit 50 to be approximately constant.

[0036] However, the oscillation control area and the heater control area may be provided in a single IC (e.g., OCXO-IC). In this case, the voltage regulator 51b that controls the voltage supplied to the crystal resonator 50 is provided in the heater control area. With this configuration, the voltage regulator 51b can be removed from the oscillation control area, and the oscillation control area can be made smaller. This reduces the heat capacity of the crystal oscillator 100 that is made up of the oscillation control area and the crystal resonator 50 that is provided integrally therewith. As a result, it becomes easier to control the temperature with low power, and the temperature controllability of the crystal oscillator 100 by the heater control area can be improved. In addition, regardless of the size of the crystal resonator 50, a design can be made in which the size of the voltage regulator 51b is increased to increase the current supplied to the voltage regulator 51b, which contributes to improving noise characteristics. In this case, even if the current of the voltage regulator 51b is increased, the temperature of the oscillation control area does not rise, so the temperature controllability of the crystal oscillator 100 by the heater control area is not reduced.

[0037] In the above embodiment, the wiring input from the voltage regulator 51b provided in the heater IC 52 to the oscillation IC 51 is the wire 6c, but the voltage regulator 51b and the oscillation IC 51 may be electrically connected by other means.

[0038] In the above embodiment, the frequency divider 51d, the output buffer 51e, etc. included in the oscillation IC 51 may be provided in the heater IC 52. With this configuration, the frequency divider 51d, the output buffer 51e, etc. can be eliminated from the oscillation IC 51 in addition to the voltage regulator 51b, so that the oscillation IC 51 can be further miniaturized. This allows the crystal unit 50 on which the oscillation IC 51 is mounted to be further miniaturized, the heat capacity of the crystal unit 50 can be further reduced, and the temperature controllability of the crystal oscillator 100 by the heater IC 52 can be further improved.

[0039] In the above embodiment, the package 2 has a base with an H-shaped cross section, but a two-tiered package may be used. Although an OCXO using a two-tiered package is not shown, the package has a recess on only one side and is stacked vertically and electrically and mechanically joined, with the upper package being hermetically sealed with a lid. In this case, the core 5 is housed in the upper package, and the capacitor 9 is housed in the lower package.

[0040] In the above embodiment, the core portion 5 and the package 2 are electrically connected by wire bonding. However, the core portion 5 and the package 2 may be electrically connected by a mechanical connection means such as a conductive adhesive or an FCB method using metal bumps.

[0041] In addition, in the above embodiment, the core unit 5 is mounted on the package 2 using the core substrate 4, but the core unit 5 may be mounted on the package 2 without using the core substrate 4. For example, the core unit 5 may be fixed to the bottom surface of the first recess 2a of the package 2 with a non-conductive adhesive.

[0042] In the above embodiment, the core unit 5 and the package 2 are electrically connected without passing through the core substrate 4, but the core unit 5 and the package 2 may be electrically connected through the core substrate 4. For example, the core substrate 4 and the package 2 may be electrically connected by a mechanical connection means such as a conductive adhesive, wire bonding, or an FCB method using metal bumps.

[0043] In the above embodiment, the core unit 5 has a three-layer structure in which the oscillation IC 51, the crystal unit 50, and the heater IC 52 are stacked, but a core unit 5 having another structure may be used. For example, in the above embodiment, the core unit 5 has a structure in which at least the oscillation IC 51, the crystal unit 50, and the heater IC 52 are stacked in this order from the top, but conversely, the core unit 5 may have a structure in which at least the heater IC 52, the crystal unit 50, and the oscillation IC 51 are stacked in this order from the top. The core unit 5 only needs to have at least the oscillation IC 51, the crystal unit 50, and the heater IC 52, and may have a structure in which, for example, a heater substrate or the like is added to the stacked structure of the oscillation IC 51, the crystal unit 50, and the heater IC 52. For example, a four-layer structure may be formed in which the heater substrate, the oscillation IC 51, the crystal unit 50, and the heater IC 52 are stacked in this order from the top, or a four-layer structure may be formed in which the heater IC 52, the crystal unit 50, the oscillation IC 51, and the heater substrate are stacked in this order from the top. In these cases, the temperature of the core unit 5 can be made more uniform by stacking the heater substrate, which is a heating element, on the oscillation IC 51.

[0044] Alternatively, the core unit 5 may not be provided, and the crystal oscillator 100 (the crystal resonator 50 and the oscillation IC 51) and the heater IC 52 may be provided separately.

[0045] In the above embodiment, a three-layer structure crystal unit 50 is used in which the crystal vibration plate 10 is sandwiched between the first sealing member 20 and the second sealing member 30, but a crystal unit with a different structure may be used. For example, a crystal unit may be used in which a crystal vibration plate is housed inside a base having a recess and made of an insulating material such as ceramic, glass, or crystal, and a lid is bonded to the base. [Explanation of symbols]

[0046] 1 OCXO (oven-controlled piezoelectric oscillator) 2 Package 50 Quartz crystal unit (piezoelectric unit) 51 Oscillation IC (oscillation control area) 51b Voltage Regulator 52 Heater IC (Heater control area) 52a Heating element

Claims

1. A thermostatic oven type piezoelectric oscillator in which a piezoelectric vibrator is sealed in a heat insulating package, an oscillation control area for supplying a voltage to the piezoelectric vibrator and controlling the piezoelectric vibration of the piezoelectric vibrator; and a heater control area for supplying a current to a heating element and controlling the temperature of the piezoelectric vibrator to be substantially constant; a voltage regulator for controlling a voltage supplied to the piezoelectric vibrator is not provided in the oscillation control region but is provided in the heater control region; The oscillation control area is provided in an oscillation IC, and the heater control area is provided in a heater IC, The oven-controlled piezoelectric oscillator is characterized in that the voltage regulator is provided in the heater IC.

2. 2. The oven-controlled piezoelectric oscillator according to claim 1, the voltage regulator provided in the heater IC is electrically connected to the oscillation IC by a single wire;

3. 3. The oven-controlled piezoelectric oscillator according to claim 1, a noise absorbing capacitor for said voltage regulator being accommodated in a space of said package different from a space accommodating said piezoelectric vibrator;

4. A thermostatic oven type piezoelectric oscillator in which a piezoelectric vibrator is hermetically sealed inside a thermally insulating package, an oscillation control area for supplying a voltage to the piezoelectric vibrator and controlling the piezoelectric vibration of the piezoelectric vibrator; and a heater control area for supplying a current to a heating element and controlling the temperature of the piezoelectric vibrator to be substantially constant; a voltage regulator for controlling a voltage supplied to the piezoelectric vibrator is not provided in the oscillation control region but is provided in the heater control region; a noise absorbing capacitor for said voltage regulator being accommodated in a space of said package different from a space accommodating said piezoelectric vibrator;

5. 5. The oven-controlled piezoelectric oscillator according to claim 4, The package includes a base having an H-shaped cross section and a first recess that is open at an upper portion and a second recess that is open at a lower portion, an oven-controlled piezoelectric oscillator, wherein at least the piezoelectric vibrator and the heating element are housed in the first recess, and the noise absorbing capacitor is housed in the second recess;

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