JP6535436B2 - Atomic resonance transition device, atomic oscillator, electronic equipment and moving body - Google Patents

Description

  The present invention relates to an atomic resonance transition device, an atomic oscillator, an electronic device, and a moving body.

An atomic oscillator is known as an oscillator having high-precision oscillation characteristics in the long run. Generally, the principle of operation of an atomic oscillator is roughly divided into a method using double resonance phenomenon by light and microwave and a method using quantum interference effect (CPT: Coherent Population Trapping) by two types of light with different wavelengths. However, any type of atomic oscillator oscillates based on the energy transfer of the atoms of alkali metals such as rubidium and cesium.
As such an atomic oscillator, for example, as disclosed in Patent Document 1, an exciting coil for applying a magnetic field to a transition portion causing resonant transition of an alkali metal, a magnetic shield for shielding the exciting coil and the transition portion from an external magnetic field What is known is provided with.

  The atomic oscillator according to Patent Document 1 normally operates in the normal mode in which the excitation current is supplied to the excitation coil, but when the frequency accuracy decreases due to the magnetization of the magnetic shield, the alternating current generator operates alternately. And selectively switch to a demagnetization mode that supplies a gradually decreasing alternating current. Then, after the demagnetization processing of the magnetic shield is performed in the demagnetization mode, the mode is switched to the normal mode again.

  However, in the atomic oscillator according to Patent Document 1, since the demagnetization process is performed so that the amount of magnetization of the magnetic shield becomes zero in the demagnetization mode, the magnetic shield in which the amount of magnetization becomes zero in the demagnetization mode is the normal mode After the transition, it takes a long time of several hours to several months until magnetization by the magnetic field from the excitation coil in the normal mode is stabilized. Therefore, in the atomic oscillator according to Patent Document 1, the fluctuation of the magnetization amount of the magnetic shield during that period affects the long-term stability of the frequency, and there is a problem that the long-term stability of the frequency decreases.

JP-A-61-131621

  An object of the present invention is to provide an atomic resonance transition device and an atomic oscillator capable of preventing or suppressing a temporal change in the amount of magnetization of a shielding portion due to a magnetic field from an excitation coil with time and improving frequency long-term stability. Another object of the present invention is to provide a highly reliable electronic device and a mobile including the atomic resonance transition device.

The present invention has been made to solve at least a part of the above-described problems, and can be realized as the following modes or application examples.
An atomic resonance transition device according to an aspect of the present invention is provided with a metal atom, a gas cell enclosing the metal atom, a magnetic shielding property, a shielding portion enclosing the gas cell, and a periphery of the gas cell. A coil for applying a DC magnetic field to the metal atoms, and a power supply capable of simultaneously generating a DC current and an alternating current which attenuates with time, and in the demagnetizing mode for demagnetizing the shielding part, the DC current and A demagnetizing magnetic field in which the alternating current is supplied to the coil, and the coil superimposes a DC magnetic field component that magnetizes the shielding portion and an AC magnetic field component that demagnetizes the shielding portion and attenuates over time In the normal mode which is generated and different from the demagnetization mode, the direct current is supplied to the coil.
The atomic resonance transition device according to another aspect of the present invention is characterized in that a deviation amount of the current value of the direct current in the demagnetization mode is 10% or less with respect to the current value of the direct current in the normal mode. I assume.
According to another aspect of the present invention, there is provided an atomic resonance transition device including a metal atom, a gas cell enclosing the metal atom, a magnetic shielding property, a shielding portion enclosing the gas cell, and a periphery of the gas cell. In the demagnetization mode, which comprises an excitation coil for applying a DC magnetic field to the metal atoms, a power supply capable of simultaneously generating a DC current and an alternating current which attenuates with time, and a demagnetization coil for demagnetizing the shielding portion The DC current and the alternating current are supplied to the degaussing coil, and the degaussing coil generates a DC magnetic field component that magnetizes the shielding portion, and an AC magnetic field component that demagnetizes the shielding portion and attenuates over time A superimposed demagnetizing magnetic field is generated, and in the normal mode different from the demagnetizing mode, the direct current is supplied to the coil.
The atomic resonance transition device according to another aspect of the present invention is characterized in that a deviation amount of the current value of the direct current in the demagnetization mode is 10% or less with respect to the current value of the direct current in the normal mode. I assume.
In the atomic resonance transition device according to another aspect of the present invention, the power supply can output a current in which the direct current and the alternating current are superimposed, and the coil or the degaussing coil is superimposed from the power supply. The above current is supplied to generate the demagnetizing magnetic field.
In the atomic resonance transition device according to another aspect of the present invention, the power supply can independently output the direct current and the alternating current, and the degaussing coil is supplied with the alternating current from the power supply. And an AC magnetic field coil generating the AC magnetic field component, and a DC magnetic field coil generating the DC magnetic field component supplied with the DC current from the power source.
It is characterized by
An atomic resonance transition apparatus according to another aspect of the present invention includes a magnetic field control unit that controls the power supply, and the magnetic field control unit can switch the power supply to the demagnetization mode and the normal mode. It is characterized by being.
The atomic resonance transition device according to another aspect of the present invention is characterized in that the excitation coil doubles as the DC magnetic field coil.
In the atomic resonance transition device according to another aspect of the present invention, the shielding portion includes an inner shielding portion and an outer shielding portion disposed inside and outside, and the DC magnetic field coil includes the metal atom and the inner side. The alternating current magnetic field coil is disposed between the inner shield and the outer shield, and the alternating current magnetic field coil is disposed between the inner shield and the outer shield.
An atomic oscillator according to an aspect of the present invention includes the above-described atomic resonance transition device.
An electronic device according to an aspect of the present invention includes the above-described atomic resonance transition device.
A mobile according to an aspect of the present invention includes the above-described atomic resonance transition device.
Application Example 1
The atomic resonance transition device of the present invention can simultaneously generate a metal atom, an exciting coil for applying a direct current magnetic field to the metal atom, a shielding portion having magnetic shielding property, a direct current, and an alternating current decaying with time. A degaussing coil for generating a degaussing magnetic field, which is supplied with a power supply, the DC current and the alternating current, and in which a DC magnetic field component and an AC magnetic field component that attenuates with time are superimposed;
It is characterized by having.

  According to such an atomic resonance transition device, the shielding portion is demagnetized in a state in which a certain amount of magnetization remains as it is magnetized by the DC magnetic field from the exciting coil by the demagnetizing magnetic field from the demagnetizing coil. be able to. Therefore, when the direct current magnetic field is generated from the exciting coil after the shielding portion is demagnetized, it is possible to prevent or suppress the temporal change in the amount of magnetization of the shielding portion due to the direct current magnetic field from the exciting coil. As a result, the strength of the magnetic field applied to the metal atoms can be stabilized, and the long-term stability of the frequency can be improved.

Application Example 2
In the atomic resonance transition device of the present invention, the power supply can output a current in which the direct current and the alternating current are superimposed,
Preferably, the demagnetizing coil is supplied with the superimposed current from the power supply to generate the demagnetizing magnetic field.
Thus, it is possible to generate a demagnetizing magnetic field in which a DC magnetic field component and an AC magnetic field component that attenuates with time are superimposed from the demagnetizing coil configured by one coil.

Application Example 3
The atomic resonance transition device of the present invention includes a magnetic field control unit that controls the power supply,
It is preferable that the magnetic field control unit be capable of switching between a demagnetization mode in which the superimposed current is supplied to the demagnetization coil and a normal mode in which the direct current is supplied to the excitation coil.
Thus, the shield can be demagnetized at an arbitrary timing.

Application Example 4
In the atomic resonance transition device of the present invention, the excitation coil preferably doubles as the demagnetization coil.
As a result, the number of parts can be reduced, and miniaturization and cost reduction of the atomic resonance transition device can be achieved.

Application Example 5
In the atomic resonance transition device of the present invention, the power supply can independently output the direct current and the alternating current, and the demagnetizing coil is supplied with the alternating current from the power supply to output the alternating magnetic field component. and exchanges field coil for generating, it is preferable that the DC current from the power source has a direct-current magnetic field coil for generating the DC magnetic field component is supplied.
This can increase the freedom of design of the atomic resonance transition device.

Application Example 6
The atomic resonance transition device of the present invention includes a magnetic field control unit that controls the power supply,
The magnetic field control unit can switch between a demagnetizing mode in which the direct current is supplied to the direct current magnetic field coil and the alternating current in the alternating current magnetic field coil, and a normal mode in which the direct current is supplied to the excitation coil. Is preferred.
Thus, the shield can be demagnetized at an arbitrary timing.

Application Example 7
In the atomic resonance transition device of the present invention, the excitation coil preferably doubles as the DC magnetic field coil.
As a result, the number of parts can be reduced, and miniaturization and cost reduction of the atomic resonance transition device can be achieved.

Application Example 8
In the atomic resonance transition device of the present invention, the shielding portion includes an inner shielding portion and an outer shielding portion which are disposed inside and outside;
The DC magnetic field coil is disposed between the metal atom and the inner shield part.
It is preferable that the alternating current magnetic field coil be disposed between the inner shielding portion and the outer shielding portion.
Thus, when the package is configured by the inner shielding portion, the package can be miniaturized. In addition, when the package is an airtight package, miniaturization makes it easy to maintain a high degree of vacuum in the package. In addition, both the inner and outer shielding portions can be efficiently demagnetized.

Application Example 9
An atomic oscillator of the present invention includes the atomic resonance transition device of the present invention.
According to such an atomic oscillator, it is possible to prevent or suppress a temporal change in the amount of magnetization of the shield portion due to the magnetic field from the excitation coil, and to improve the long-term stability of the frequency.
Application Example 10
An electronic device of the present invention includes the atomic resonance transition device of the present invention.
Thus, an electronic device having excellent reliability can be provided.
Application Example 11
The moving body of the present invention is characterized by including the atomic resonance transition device of the present invention.
Thereby, the mobile object which is excellent in reliability can be provided.

FIG. 1 is a perspective view showing an atomic oscillator according to a first embodiment of the present invention. It is a schematic diagram which shows schematic structure of the atomic oscillator shown in FIG. It is a figure for demonstrating the energy state of the alkali metal in the gas cell with which the atomic oscillator shown in FIG. 1 was equipped. It is a graph which shows the relationship of the frequency difference of two lights from a light emission part, and the detection intensity in a light detection part about the light emission part and the light detection part with which the atomic oscillator shown in FIG. 1 was equipped. It is a longitudinal cross-sectional view of the atomic oscillator shown in FIG. It is sectional drawing which expands and shows a part of FIG. It is a block diagram for demonstrating the magnetic field control part shown in FIG. (A) is a graph showing a temporal change of the current flowing to the exciting coil in the conventional demagnetization mode, (b) is a shield portion at the transition from the demagnetization mode using the current shown in (a) to the normal mode It is a graph which shows the time-dependent change of the amount of magnetization. (A) is a graph showing a temporal change of the current flowing from the power source shown in FIG. 7 to the exciting coil (demagnetizing coil) in the demagnetizing mode, (b) is a demagnetizing mode using the current shown in (a) It is a graph which shows a time-dependent change of the amount of magnetization of a shield part at the time of shifting to. It is a graph which shows the modification of the time-dependent change of the electric current which flows into an excitation coil (demagnetization coil) at the time of demagnetization mode from the power supply shown in FIG. It is sectional drawing which expands and shows a part of atomic oscillator concerning 2nd Embodiment of this invention. It is a block diagram for demonstrating the magnetic field control part of the atomic oscillator shown in FIG. It is a graph which shows a time-dependent change of the electric current which flows into a degaussing coil at the time of degaussing mode from the power supply shown in FIG. It is a system configuration outline figure at the time of using an atomic oscillator of the present invention for a positioning system using GPS satellites. It is a perspective view showing the composition of the mobile (automobile) provided with the atomic oscillator of the present invention.

Hereinafter, the atomic resonance transition device, the atomic oscillator, the electronic device, and the moving body of the present invention will be described in detail based on embodiments shown in the attached drawings.
1. Atomic oscillator (quantum interference device)
First, the atomic oscillator of the present invention (atomic oscillator provided with the atomic resonance transition device of the present invention) will be described. Although an example in which the atomic resonance transition device of the present invention is applied to an atomic oscillator is described below, the atomic resonance transition device of the present invention is not limited to this, and in addition to atomic oscillators, for example, magnetic sensors, quantum It is applicable also to a memory etc.

  FIG. 1 is a perspective view showing an atomic oscillator according to a first embodiment of the present invention, and FIG. 2 is a schematic view showing a schematic configuration of the atomic oscillator shown in FIG. FIG. 3 is a view for explaining the energy state of the alkali metal in the gas cell provided in the atomic oscillator shown in FIG. Further, FIG. 4 shows the relationship between the frequency difference between two light from the light emitting portion and the detection intensity in the light detecting portion for the light emitting portion and the light detecting portion provided in the atomic oscillator shown in FIG. It is a graph. 5 is a longitudinal sectional view of the atomic oscillator shown in FIG. 1, and FIG. 6 is an enlarged sectional view showing a part of FIG.

  In FIGS. 1, 5 and 6, for convenience of explanation, X axis, Y axis and Z axis are illustrated as three axes orthogonal to each other, and “+” at the tip end of each illustrated arrow (Plus) ”, and the proximal end side as“ − (minus) ”. In the following, for convenience of explanation, a direction parallel to the X axis is referred to as “X axis direction”, a direction parallel to the Y axis is referred to as “Y axis direction”, and a direction parallel to the Z axis is referred to as “Z axis direction” Further, the + Z direction side (upper side in FIG. 5) is referred to as “upper”, and the −Z direction side (lower side in FIG. 5) as “lower”.

The atomic oscillator 1 shown in FIG. 1 is an atomic oscillator using a quantum interference effect. The atomic oscillator 1 utilizing this quantum interference effect can be miniaturized as compared to an atomic oscillator utilizing the double resonance phenomenon.
As shown in FIG. 1, the atomic oscillator 1 supports a first unit 2 (light emitting side unit), a second unit 3 (light detecting side unit), a package 5 containing these, and a package 5. A wiring board 6 (substrate) and a control unit 7 mounted on the wiring board 6 are provided.

Here, as shown in FIGS. 1 and 2, the first unit 2 includes a light emitting unit 21 and a first package 22 (light emitting side package) that accommodates the light emitting unit 21.
The second unit 3 further includes a gas cell 31, a light detection unit 32, a heater 33, a temperature sensor 34, a coil 35, and a second package 36 (light detection side package) that accommodates these.
The first unit 2 and the second unit 3 are electrically connected to the control unit 7 via the wiring (not shown) of the wiring board 6 and are drive-controlled by the control unit 7.

First, the principle of the atomic oscillator 1 will be briefly described.
In the atomic oscillator 1, gaseous alkali metals (metal atoms) such as rubidium, cesium, and sodium are enclosed in the gas cell 31.
As shown in FIG. 3, the alkali metal has a three-level energy level, and three states of two ground states (ground states 1 and 2) having different energy levels and an excited state. Can take Here, ground state 1 is a lower energy state than ground state 2.

When the gaseous alkali metal is irradiated with two types of resonance lights 1 and 2 having different frequencies with respect to such a gaseous alkali metal, the frequency ω 1 of the resonance light 1 and the frequency ω 2 of the resonance light 2 are The light absorptivity (light transmittance) of the alkali metal of the resonance lights 1 and 2 changes in accordance with the difference (ω1−ω2) of
Then, when the difference (ω1−ω2) between the frequency ω1 of the resonant light 1 and the frequency ω2 of the resonant light 2 matches the frequency corresponding to the energy difference between the ground state 1 and the ground state 2, The excitation to the excited state stops respectively. At this time, both of the resonance lights 1 and 2 are transmitted without being absorbed by the alkali metal. Such a phenomenon is called CPT phenomenon or electromagnetically induced transparency (EIT).
The light emitting unit 21 emits two types of light (resonant light 1 and resonant light 2) having different frequencies as described above toward the gas cell 31.

  For example, when the light emitting unit 21 fixes the frequency ω1 of the resonant light 1 and changes the frequency ω2 of the resonant light 2, the difference between the frequency ω1 of the resonant light 1 and the frequency ω2 of the resonant light 2 (ω1-ω2 Is equal to the frequency .omega.0 corresponding to the energy difference between the ground state 1 and the ground state 2, the detection intensity of the light detection unit 32 sharply increases as shown in FIG. Such a steep signal is detected as an EIT signal. This EIT signal has an intrinsic value determined by the type of alkali metal. Therefore, by using such an EIT signal as a reference, a highly accurate oscillator can be realized.

Hereinafter, each part of the atomic oscillator 1 will be sequentially described in detail.
(1st unit)
As described above, the first unit 2 includes the light emitting unit 21 and the first package 22 accommodating the light emitting unit 21.
[Light emitting part]
The light emitting unit 21 has a function of emitting excitation light for exciting alkali metal atoms in the gas cell 31.
More specifically, the light emitting unit 21 emits two types of light (resonant light 1 and resonant light 2) having different frequencies as described above.

The frequency ω1 of the resonance light 1 can excite the alkali metal in the gas cell 31 from the ground state 1 described above to the excited state.
The frequency ω2 of the resonance light 2 can excite the alkali metal in the gas cell 31 from the ground state 2 described above to the excited state.
The light emitting portion 21 is not particularly limited as long as it can emit the excitation light as described above. For example, a semiconductor laser such as a vertical cavity surface emitting laser (VCSEL) can be used.
Further, such a light emitting portion 21 is temperature-controlled to a temperature (first temperature) different from that of the gas cell 31 to be described later, for example, about 30 ° C. by a temperature control element (heating resistor, Peltier element, etc.) not shown. Ru.

[First package (light emitting side package)]
The first package 22 accommodates the light emitting unit 21 described above.
As shown in FIG. 5, the first package 22 includes a base 221 (light emitting side base) and a lid 222 (light emitting side lid).
The base 221 supports the light emitting unit 21 directly or indirectly. In the present embodiment, the base body 221 has a plate shape, and has a circular shape in plan view.

The light emitting unit 21 (mounting component) is installed (mounted) on one surface (mounting surface) of the base 221. Further, on the other surface of the base body 221, as shown in FIG. 5, a plurality of terminals 223 (leads) project in the −X axis direction. The plurality of terminals 223 are electrically connected to the light emitting unit 21 via a wire (not shown).
As shown in FIG. 5, the plurality of terminals 223 extend in the X axis direction, and are arranged in one direction (the Y axis direction in the present embodiment) so as to be parallel to each other.

The constituent material of such a base 221 is not particularly limited, and, for example, ceramic materials, metal materials, resin materials and the like can be used, but metal materials are preferably used. Thus, when the lid 222 is made of a metal material, the base body 221 and the lid 222 can be airtightly relatively easily and reliably joined by welding.
A lid 222 covering the light emitting portion 21 on the base 221 is joined to such a base 221.

The lid 222 has a bottomed cylindrical shape whose one end is open. In the present embodiment, the cylindrical portion of the lid 222 has a cylindrical shape.
The opening at one end of the lid 222 is closed by the base 221 described above.
A window 23 is provided at the other end of the lid 222, that is, at the bottom opposite to the opening of the lid 222.
The window portion 23 is provided on the optical axis a between the gas cell 31 and the light emitting portion 21.

And the window part 23 has transparency with respect to the excitation light mentioned above. Thus, the light emitting portion 21 can be accommodated in the first package 22 while allowing the emission of the excitation light from the light emitting portion 21 to the outside of the first package 22.
In the present embodiment, the window portion 23 is configured by a lens. Thereby, the excitation light LL can be irradiated to the gas cell 31 without waste.

Further, the window portion 23 has a function of making the excitation light LL parallel light. As a result, it is possible to simply and reliably prevent the excitation light LL from being reflected by the inner wall of the gas cell 31 while increasing the amount of the alkali metal irradiated with the excitation light LL. Therefore, the resonance of the excitation light in the gas cell 31 can be suitably generated, and as a result, the oscillation characteristic of the atomic oscillator 1 can be enhanced.
The window portion 23 is not limited to a lens as long as it has transparency to excitation light, and for example, an optical component other than a lens such as a polarizing plate, a λ / 4 wavelength plate, or a light reduction filter It may be a simple light transmitting plate member. In addition, these optical components may be provided between the light emitting unit 21 and the gas cell 31 described later, and may be provided, for example, between the window unit 37 and the light emitting unit 21. Also, it may be provided between the first package 22 and the second package 36.

  The constituent material of the portion other than the window portion 23 of the lid 222 is not particularly limited, and for example, ceramic materials, metal materials, resin materials and the like can be used, but metal materials are preferably used, It is more preferable to use an Fe-Ni-based alloy such as Kovar or Permalloy, and it is further preferable to use Kovar. Thus, the base body 221 and the lid 222 can be airtightly relatively easily and reliably joined by welding.

  The lid 222 may be made of one type of material, or may be configured by mixing or laminating two or more types of materials. When the portion other than the window portion 23 of the lid 222 is made of a material having transparency to excitation light, the portion other than the window portion 23 of the lid 222 and the window portion 23 are integrally formed. can do. When the portion other than the window portion 23 of the lid 222 is made of a material having no permeability to excitation light, the portion other than the window portion 23 of the lid 222 and the window portion 23 are separated. These may be formed and joined by a known joining method.

Moreover, it is preferable that the base 221 and the lid 222 be airtightly joined. That is, the inside of the first package 22 is preferably an airtight space. As a result, the inside of the first package 22 can be brought into a reduced pressure state (a state of reduced pressure from atmospheric pressure) or an inert gas filled state, and as a result, the characteristics of the atomic oscillator 1 can be improved.
The method of joining the base body 221 and the lid 222 is not particularly limited, and, for example, brazing, seam welding, energy beam welding (laser welding, electron beam welding, etc.) can be used.

Between the base 221 and the lid 222, a bonding member for bonding these may be interposed.
In addition, components other than the light emitting unit 21 described above may be accommodated in the first package 22.
For example, in the first package 22, a temperature control element, a temperature sensor, or the like that adjusts the temperature of the light emitting unit 21 may be accommodated. As such a temperature control element, a heating resistor (heater), a Peltier element, etc. are mentioned, for example.
The first package 22 as described above is held by the package 5 described later so that the base body 221 is disposed on the opposite side to the second package 36.

(2nd unit)
As described above, the second unit 3 includes the gas cell 31, the light detection unit 32, the heater 33, the temperature sensor 34, the coil 35, and the second package 36 that accommodates these.
[Gas cell]
In the gas cell 31, gaseous alkali metals such as rubidium, cesium, sodium and the like are enclosed. Further, in the gas cell 31, a rare gas such as neon or argon, an inert gas such as nitrogen, or the like is enclosed as a buffer gas as necessary.
As shown in FIG. 6, the gas cell 31 has a main body 311 having a columnar through hole, and a pair of windows 312 and 313 for closing both openings of the through hole. Thus, the internal space S1 in which the alkali metal is sealed as described above is formed.

  The material constituting the main body portion 311 is not particularly limited, and examples thereof include metal materials, resin materials, glass materials, silicon materials, quartz crystals and the like, but the airtight bonding with the windows 312 and 313 is anodic bonding, direct bonding It is preferable to use a glass material and a silicon material from the viewpoint of being easy to use. Further, by forming the main body portion 311 with a silicon material, the main body portion 311 can be easily and precisely formed by microfabrication using MEMS technology.

Each of the windows 312 and 313 has transparency to the excitation light from the light emitting unit 21 described above. The one window portion 313 is for transmitting the excitation light incident into the gas cell 31, and the other window portion 312 is for transmitting the excitation light emitted from the inside of the gas cell 31.
Therefore, the material constituting the windows 312 and 313 of the gas cell 31 is not particularly limited as long as it has the permeability to the excitation light as described above, and examples thereof include a glass material, quartz crystal and the like.

The windows 312 and 313 are airtightly joined to the main body 311. Thereby, the internal space S1 of the gas cell 31 can be made airtight.
The method of bonding the main body 311 of the gas cell 31 and the windows 312 and 313 is determined according to the constituent materials of these and is not particularly limited. For example, a bonding method using an adhesive, a direct bonding method, and an anode A bonding method or the like can be used.
The gas cell 31 as described above is temperature-controlled by the heater 33 to a temperature (second temperature) different from that of the light emitting portion 21 described above, for example, about 70.degree.

[Light detection unit]
The light detection unit 32 has a function of detecting the intensity of the excitation light LL (resonance lights 1 and 2) transmitted through the inside of the gas cell 31.
The light detection unit 32 is not particularly limited as long as it can detect the excitation light as described above. For example, a light detector (light receiving element) such as a solar cell or a photodiode can be used.

[heater]
The heater 33 has a function of heating the gas cell 31 (more specifically, the alkali metal in the gas cell 31) described above. Thereby, the alkali metal in the gas cell 31 can be maintained in a gaseous state with an appropriate concentration.
The heater 33 generates heat when it is energized, and as shown in FIG. 6, it comprises heating resistors 331 and 332 provided on the outer surface of the gas cell 31. Such heating resistors 331 and 332 are formed using, for example, chemical vapor deposition (CVD) such as plasma CVD or thermal CVD, dry plating such as vacuum deposition, sol-gel method, or the like.

Here, the heating resistor 331 is provided on the window 312 of the gas cell 31, and the heating resistor 332 is provided on the window 313 of the gas cell 31.
The heating resistors 331 and 332 are materials having transparency to excitation light, specifically, for example, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), In ₃ O ₃ , SnO ₂ , Sb-containing SnO ₂ composed of a transparent electrode material such as an oxide such as Al-containing ZnO.

The heater 33 is not limited to the above-described configuration as long as it can heat the gas cell 31. The heater 33 may be noncontact with the gas cell 31. Further, the gas cell 31 may be heated using a Peltier element instead of the heater 33 or in combination with the heater 33.
The heater 33 as described above is electrically connected to the temperature control unit 72 of the control unit 7 described later, and is energized.

[Temperature sensor]
The temperature sensor 34 detects the temperature of the heater 33 or the gas cell 31. Then, based on the detection result of the temperature sensor 34, the calorific value of the heater 33 described above is controlled. Thereby, the alkali metal atom in the gas cell 31 can be maintained at a desired temperature.

The installation position of the temperature sensor 34 is not particularly limited, and may be on the heater 33 or on the outer surface of the gas cell 31, for example.
The temperature sensors 34 are not particularly limited, and various known temperature sensors such as thermistors and thermocouples can be used.
The temperature sensor 34 as described above is electrically connected to a temperature control unit 72 of the control unit 7 described later via a wiring (not shown).

[coil]
The coil 35 has a function of generating a magnetic field by energization.
In the present embodiment, the coil 35 is in the form of a cylinder, and the axis line of the coil 35 is a solenoid coil that is disposed along the X-axis direction and surrounds the gas cell 31. Such a coil 35 generates a magnetic field in the gas cell 31 along the X-axis direction. The coil 35 is not limited to the solenoid type, and may be a Helmholtz type disposed to face each other via the gas cell 31.

  The coil 35 usually constitutes an "excitation coil" which is supplied with a direct current from a power source 4 described later to generate a direct current magnetic field. This DC magnetic field is applied to the alkali metal in the gas cell 31. Thus, Zeeman splitting can widen the gap between the degenerate different energy levels of the alkali metal and improve the resolution. As a result, the accuracy of the oscillation frequency of the atomic oscillator 1 can be enhanced. In the following, a DC magnetic field for Zeeman splitting of such an alkali metal is also referred to as “excitation magnetic field”. Further, a direct current for generating an excitation magnetic field is also referred to as “excitation current”.

  In addition, the coil 35 is supplied with a current in which an excitation current and an alternating current (hereinafter also referred to as a “demagnetizing current” or a “decaying current”) that attenuates with time are superimposed from the power supply 4 described later. Construct a "demagnetizing coil" that generates a demagnetizing magnetic field. Thereby, the second package 36 can be demagnetized when necessary. In particular, the second package 36 is magnetized by the DC magnetic field from the coil 35 by the demagnetizing magnetic field from the coil 35 because the DC magnetic field component and the AC magnetic field component that attenuates over time are superimposed. It is possible to demagnetize in the state in which the same amount of magnetization remains. Therefore, when the excitation magnetic field is generated from the coil 35 after the second package 36 is demagnetized, it is possible to prevent or suppress the temporal change in the amount of magnetization of the second package 36 due to the excitation magnetic field from the coil 35 . As a result, the strength of the magnetic field applied to the alkali metal in the gas cell 31 can be stabilized, and the long-term stability of the frequency can be improved.

Further, since the coil 35, which is an excitation coil for generating an excitation magnetic field, also serves as a demagnetization coil for generating a demagnetization magnetic field, the number of parts can be reduced, and miniaturization and cost reduction of the atomic oscillator 1 can be achieved.
Here, the coil 35 is disposed between the alkali metal in the gas cell 31 and the second package 36. Thereby, it becomes possible to use the coil 35 which is an exciting coil as a demagnetizing coil.
The exciting magnetic field and the demagnetizing magnetic field will be described in detail later together with the magnetic field control unit 73 and the power supply 4.
The coil 35 as described above is electrically connected to a magnetic field control unit 73 of the control unit 7 described later via a wiring (not shown) and a power supply 4 described later (see FIG. 7).

[Second package (light detection package)]
The second package 36 accommodates the gas cell 31, the light detection unit 32, the heater 33, the temperature sensor 34, and the coil 35 described above.
The second package 36 has a magnetic shielding property and constitutes a "shielding portion" which shields the alkali metal in the gas cell 31 from the external magnetic field. In the case where the package 5 to be described later has magnetic shielding properties and constitutes the "outside shielding portion" of the "shielding portion", the second package 36 disposed inside the package 5 is the "inside shielding of the" shielding portion ". Make up the

The second package 36 can be configured in the same manner as the first package 22 of the first unit 2 described above.
Specifically, as shown in FIGS. 5 and 6, the second package 36 includes a base 361 (light detection side base) and a lid 362 (light detection side lid).
The base 361 supports the gas cell 31, the light detection unit 32, the heater 33, the temperature sensor 34, and the coil 35 directly or indirectly. In the present embodiment, the base 361 has a disk shape.

  The gas cell 31, the light detection unit 32, the heater 33, the temperature sensor 34, and the coil 35 (a plurality of mounting components) are installed (mounted) on one surface (mounting surface) of the base 361. In the present embodiment, the gas cell 31, the light detection unit 32 and the heater 33 are mounted on the base 361 via the substrate 38. Further, on the other surface of the base 361, a plurality of terminals 363 (leads) project in the + X axis direction. The plurality of terminals 363 are electrically connected to the light detection unit 32, the heater 33, the temperature sensor 34, and the coil 35 via a wire (not shown).

The plurality of terminals 363 respectively extend in the X-axis direction, and are arranged in one direction (in the present embodiment, the Y-axis direction) so as to be parallel to each other. The arrangement of the plurality of terminals 363 is not limited to this, and is arbitrary.
As a constituent material of such a base 361, a material having magnetic shielding properties is used, and for example, soft magnetic materials such as Fe, various iron-based alloys (silicon iron, permalloy, amorphous, sendust, kovar) and the like can be mentioned. Among them, from the viewpoint of excellent magnetic shielding properties, it is preferable to use an Fe-Ni-based alloy such as Kovar or Permalloy, and from the viewpoint that airtight bonding between the base 361 and the lid 362 can be performed simply and reliably by welding. It is more preferable to use
A lid 362 that covers the gas cell 31, the light detection unit 32, the heater 33, the temperature sensor 34, and the coil 35 is joined to such a base 361.

The lid 362 has a bottomed cylindrical shape whose one end is open. In the present embodiment, the cylindrical portion of the lid 362 has a cylindrical shape.
The opening at one end of the lid 362 is closed by the base 361 described above.
A window 37 is provided at the other end of the lid 362, that is, at the bottom opposite to the opening of the lid 362.
The window portion 37 is provided on the optical axis a between the gas cell 31 and the light emitting portion 21.

  And the window part 37 has transparency with respect to the excitation light mentioned above. Thus, the gas cell 31 and the light detection unit 32 can be accommodated in the second package 36 while allowing the excitation light from the light emitting unit 21 to enter the second package 36. Therefore, by using the second package 36 in combination with the first package 22 as described above, it is possible to secure the optical path of the excitation light from the light emitting unit 21 to the light detecting unit 32 via the gas cell 31 21 and the gas cell 31 can be housed in separate packages which are not in contact with each other.

In the present embodiment, the window portion 37 is formed of a light transmitting plate-like member. And the window part 37 is joined to parts other than the window part 37 of the cover 362 by the well-known joining method.
The window portion 37 is not limited to a plate-like member having light transmittance as long as it has transparency to excitation light, and is an optical component such as a lens, a polarizing plate, or a λ / 4 wavelength plate, for example. May be

As a constituent material of portions other than the window part 37 of such a lid 362, what is necessary is to have a magnetic shielding property, and the same material as the constituent material of the base 361 described above can be used.
Further, it is preferable that the base 361 and the lid 362 be airtightly joined. That is, it is preferable that the inside of the second package 36 be an airtight space. As a result, the inside of the second package 36 can be brought into a reduced pressure state (a pressure reduced state from atmospheric pressure) or an inert gas filled state, and as a result, the characteristics of the atomic oscillator 1 can be improved.

The method of joining the base 361 and the lid 362 is not particularly limited, and, for example, brazing, seam welding, energy beam welding (laser welding, electron beam welding, etc.) can be used.
A bonding member for bonding these may be interposed between the base 361 and the lid 362.

Further, at least the gas cell 31 and the light detection unit 32 may be accommodated in the second package 36, and components other than the gas cell 31, the light detection unit 32, the heater 33, the temperature sensor 34, and the coil 35 described above. May be stored.
The second package 36 as described above is held by the package 5 described later so that the base 361 is disposed on the opposite side to the first package 22.

(package)
The package 5 has a function of housing the first package 22 and the second package 36 described above.
This package 5 has an internal space S that accommodates the first unit 2 and the second unit 3 in a state of being disposed apart from each other, and the internal space S is in a state of being decompressed below atmospheric pressure. There is. As a result, heat transfer by heat conduction and convection between the package 5 and the first unit 2 and the second unit 3 and between the first unit 2 and the second unit 3 can be suppressed.
Specifically, as shown in FIG. 5, the package 5 has a main body 50 having a recess 51 opened to the upper side, and a lid 54 for closing the recess 51.
The first package 22 and the second package 36 are installed in the recess 51 of the main body 50.

  Further, the recess 51 has a shape that regulates the position and attitude of the first package 22 and the second package 36. Accordingly, by installing the first package 22 and the second package 36 in the recess 51 of the package 5, it is possible to position the optical system including the light emitting unit 21 and the light detecting unit 32. Therefore, the installation of the first package 22 and the second package 36 on the package 5 can be facilitated.

Here, the recess 51 extends in the X-axis direction, the first package 22 is disposed on one end side (left side in FIG. 5), and the other side (right side in FIG. 5) , The second package 36 is arranged.
The first package 22 and the second package 36 are arranged such that the axes of the cylindrical lids 222 and 362 are parallel to the extending direction (X-axis direction) of the recess 51. Thereby, the first package 22 and the second package 36 are arranged such that the axes of the lid 222 and the lid 362 are aligned or parallel to each other.

In the present embodiment, the cross section of the recess 51 is rectangular.
In addition, a support 52 (first support) for supporting the base 221 of the first package 22 is provided on one end side (left side in FIG. 5) of the main body 50, and the other end (FIG. 5) of the main body 50. A support 53 (second support) for supporting the base 361 of the second package 36 is provided on the right side).

  As described above, the support portion 52 supports the base body 221 and the support portion 53 facing the support portion 52 supports the base body 361, so that the contact portion between the first package 22 and the package 5 and the second package 36. The distance between the contact portion and the package 5 can be increased. Therefore, heat conduction between the first package 22 and the second package 36 through the package 5 can be more effectively suppressed.

  Also, the lid 222 and the lid 362 are not in contact with the package 5, respectively. Thereby, heat conduction between the first package 22 and the second package 36 through the package 5 can be more effectively suppressed. In particular, since the cylindrical sections of the lids 222 and 362 are cylindrical while the cross section of the recess 51 is rectangular, the distance between the side surfaces of the lids 222 and 362 and the package 5 is relatively large. A large gap can be formed. As a result, the conduction of heat from the lids 222 and 362 to the package 5 can be extremely suppressed. Moreover, even if the side surfaces of the lids 222 and 362 are in contact with the package 5, the contact area can be reduced.

  Here, the support portion 52 has an installation surface parallel to the Y axis and the Z axis. The surface of the base 221 of the first package 22 opposite to the lid 222 is in contact with or in proximity to the installation surface. Thereby, the position and posture of the first package 22 with respect to the package 5 can be regulated. The base body 221 can be fixed to the support portion 52 using an adhesive, for example.

  Further, the support portion 52 is formed with a plurality of through holes 521 through which the plurality of terminals 223 of the first package 22 described above are inserted. That is, the support portion 52 is in the form of a socket in which the first package 22 is mounted. Also in this case, the position and posture of the first package 22 with respect to the package 5 can be regulated. The plurality of terminals 223 can be fixed to the support 52 by, for example, solder.

The plurality of terminals 223 pass through the plurality of through holes 521. Thus, the tip of each terminal 223 protrudes from the package 5.
Here, the plurality of through holes 521 are provided corresponding to the plurality of terminals 223, extend in the X axis direction, and are aligned in the Y axis direction. Therefore, the portions of the plurality of terminals 223 protruding from the package 5 are also aligned in the Y-axis direction.

  Similarly, the support 53 has a mounting surface parallel to the Y axis and the Z axis. The surface opposite to the cover 362 of the base 361 of the second package 36 described above is in contact with or close to the installation surface. Thereby, the position and attitude of the second package 36 with respect to the package 5 can be regulated. The base 361 can be fixed to the support portion 53 using, for example, an adhesive.

Further, the support portion 53 is formed with a plurality of through holes 531 through which the plurality of terminals 363 of the second package 36 described above are inserted. That is, the support portion 53 is in the form of a socket to which the second package 36 is attached. Also in this case, the position and attitude of the second package 36 with respect to the package 5 can be regulated. The plurality of terminals 363 can be fixed to the support portion 53 by, for example, solder.
The plurality of terminals 363 pass through the plurality of through holes 531. Thus, the tip of each terminal 363 protrudes from the package 5.

Here, the plurality of through holes 531 are provided corresponding to the plurality of terminals 363, respectively extend in the X axis direction, and are aligned in the Y axis direction. Therefore, the portions of the plurality of terminals 363 protruding from the package 5 are also aligned in the Y-axis direction.
A lid 54 for closing the opening of the recess 51 is joined to such a main body 50.
The lid 54 has a flat plate shape.
Moreover, it is preferable that the main body 50 and the lid 54 be airtightly joined. That is, the inside of the package 5 is preferably an airtight space. As a result, the inside of the package 5 can be brought into a reduced pressure state (a pressure reduced state from atmospheric pressure) or an inert gas filled state.

The method of joining the main body 50 and the lid 54 is not particularly limited, and, for example, brazing, seam welding, energy beam welding (laser welding, electron beam welding, etc.) can be used.
The constituent materials of the main body 50 and the lid 54 of the package 5 are not particularly limited, and examples thereof include metal materials, resin materials, ceramic materials, and the like.

  When a metal material is used as a constituent material of the main body 50 and the lid 54, the main body 50 and the lid 54 can be airtightly relatively easily and reliably joined by welding. In particular, as such a metal material, soft magnetic materials such as Fe and various iron-based alloys (silicon iron, permalloy, amorphous, sendust, kovar) are preferably used, and Fe-Ni-based alloys such as kovar and permalloy are preferably used. Is more preferred, and permalloy is more preferred. Thereby, the magnetic shielding property of the package 5 can be made excellent. Here, when the package 5 has a magnetic shielding property, the package 5 constitutes an "outside shielding part" of the "shielding part".

On the other hand, when nonmetallic materials such as resin material and ceramic material are used as constituent materials of the main body 50 and the lid 54, the heat conduction between the first package 22 and the second package 36 through the package 5 is reduced. be able to. As a result, thermal interference between the light emitting portion 21 and the gas cell 31 can be effectively prevented or suppressed.
The resin material constituting the package 5 is not particularly limited, and examples thereof include polyethylene, polyolefin such as ethylene-vinyl acetate copolymer (EVA), acrylic resin, acrylonitrile-butadiene-styrene copolymer (ABS resin), Acrylonitrile-styrene copolymer (AS resin), polyethylene terephthalate (PET), polyether, polyether ketone (PEK), polyether ether ketone (PEEK), styrene type, polyolefin type, polyvinyl chloride type, polyurethane type, polyester Thermoplastic elastomers such as polyamides, polybutadienes, transpolyisoprenes, fluoro rubbers, chlorinated polyethylenes, epoxy resins, phenol resins, urea resins, melamine resins, unsaturated polyesters, Ricone resin, polyurethane, etc., or copolymers, blends, polymer alloys, etc. mainly containing these, and one or more of them are used in combination (for example, as a laminate of two or more layers) be able to.

The ceramic material constituting the package 5 is not particularly limited, but, for example, various glasses, oxide ceramics such as alumina, silica, titania, zirconia, yttria, calcium phosphate, silicon nitride, aluminum nitride, nitride nitride, etc. Examples thereof include nitride ceramics such as titanium and boron nitride, carbide-based ceramics such as graphite and tungsten carbide, and other ferroelectric materials such as barium titanate, strontium titanate, PZT, PLZT, and PLLZT.
The package 5 as described above is supported by the wiring board 6.

(Wiring board)
The wiring board 6 has a wiring (not shown), and via the wiring, an electronic component such as the control unit 7 mounted on the wiring board 6, a plurality of terminals 223 of the first package 22 and a plurality of second packages It has a function of electrically connecting the terminal 363.
The wiring board 6 also has a function of supporting the package 5 via the plurality of terminals 223 and the plurality of terminals 363.

In the present embodiment, as shown in FIG. 5, in the wiring substrate 6, through holes 61 penetrating in the thickness direction are formed.
The package 5 is inserted into the through hole 61. Thus, the overall height of the device can be reduced as compared to the case where the package 5 is mounted on the surface of the wiring substrate 6. The through holes 61 may be omitted, and in this case, the package 5 may be disposed on one surface of the wiring substrate 6.

A plurality of terminals 62 and a plurality of terminals 63 are provided on one surface of the wiring substrate 6 around such a through hole 61.
The plurality of terminals 62 are provided corresponding to the plurality of terminals 223 of the first package 22 described above. The plurality of corresponding terminals 223 are joined to the plurality of terminals 62, respectively.

The plurality of terminals 63 are provided corresponding to the plurality of terminals 363 of the second package 36 described above. A plurality of corresponding terminals 363 are joined to the plurality of terminals 63, respectively.
By these junctions, the package 5 is supported by the wiring board 6 through the plurality of terminals 223 and the plurality of terminals 363, and the plurality of terminals 223 are electrically connected to the plurality of terminals 62, respectively. Are electrically connected to the plurality of terminals 63, respectively.

  The method of joining the terminals 223 and 62 and the method of joining the terminals 363 and 63 are not particularly limited as long as they can be joined while securing the electrical continuity of the joint, for example, for example And a bonding method using solder, a bonding method using an anisotropic conductive adhesive, and the like. Moreover, when the terminal 223 and the terminal 62 are comprised like a crimp terminal, the terminal 223 and the terminal 62 can also be joined by crimping. Similarly, when the terminal 363 and the terminal 63 are configured as a crimped terminal, the terminal 363 and the terminal 63 can be joined by crimping.

Each of the plurality of terminals 223 and 363 is electrically connected to the control unit 7 via a wire (not shown).
Although various printed wiring boards can be used as such a wiring board 6, from the viewpoint of securing the rigidity necessary to support the package 5, a board having a rigid portion, for example, a rigid board, a rigid flexible board It is preferable to use

Even when a wiring board having no rigid portion (for example, a flexible board) is used as the wiring board 6, for example, a reinforcing member for improving rigidity is joined to the wiring board. The rigidity necessary to support the package 5 can be secured.
A control unit 7 is provided on one surface of the wiring substrate 6 as described above. Note that electronic components other than the control unit 7 may be mounted on the wiring board 6.

[Control unit]
The control unit 7 shown in FIG. 2 has a function of controlling the heater 33, the coil 35 and the light emitting unit 21 respectively.
In the present embodiment, the control unit 7 is configured by an IC (Integrated Circuit) chip mounted on the wiring substrate 6.
The control unit 7 includes an excitation light control unit 71 that controls the frequency of the resonance light 1 and 2 of the light emitting unit 21, a temperature control unit 72 that controls the temperature of alkali metal in the gas cell 31, and the gas cell 31. And a magnetic field control unit 73 that controls a magnetic field to be applied.

  The excitation light control unit 71 controls the frequencies of the resonance lights 1 and 2 emitted from the light emitting unit 21 based on the detection result of the light detection unit 32 described above. More specifically, the excitation light control unit 71 emits light from the light emission unit 21 such that (ω1−ω2) detected by the light detection unit 32 described above becomes the frequency ω0 unique to the alkali metal described above. The frequency of the resonant light 1 and 2 is controlled. Further, the excitation light control unit 71 controls the center frequency of the resonance light 1 and 2 emitted from the light emission unit 21.

Further, the temperature control unit 72 controls the energization of the heater 33 based on the detection result of the temperature sensor 34. Thereby, the gas cell 31 can be maintained in a desired temperature range.
Further, the magnetic field control unit 73 has a function of controlling the magnetic field generated by the coil 35.
The magnetic field control unit 73 is connected to the power supply 4 for supplying a current to the coil 35, and controls the drive of the power supply 4 to control the magnetic field generated by the coil 35.

The power supply 4 outputs a current supplied to the coil 35.
In particular, the power supply 4 is configured to be capable of simultaneously generating an excitation current and a demagnetization current. In the present embodiment, the power supply 4 is configured to be able to output a current in which the excitation current and the demagnetization current are superimposed when the excitation current and the demagnetization current are simultaneously generated. Thereby, the degaussing magnetic field as described above can be generated.

The magnetic field control unit 73 and the power supply 4 will be described in detail below.
FIG. 7 is a block diagram for explaining the magnetic field control unit shown in FIG.
As shown in FIG. 7, the power supply 4 generates an excitation current generation unit 41 (DC power supply) that generates an excitation current that is a direct current, and a demagnetization current that generates alternating current (attenuated alternating current) that attenuates with time. It includes a current generation unit 42 (AC power supply), and a current superposition unit 43 that superimposes the excitation current and the demagnetization current.

The excitation current generation unit 41 is configured of, for example, a DC power supply circuit (constant current circuit). It is preferable that the excitation current generating unit 41 is configured to be capable of adjusting the current value of the generated excitation current. Thereby, the frequency characteristic of the atomic oscillator 1 can be adjusted when desired.
The demagnetization current generation unit 42 is configured to include, for example, an AC power supply circuit and a variable transformer or variable resistor. The frequency of the AC power supply circuit included in the demagnetizing current generation unit 42 may be variable.
The current superimposing unit 43 is configured of, for example, an adder.

With such a relatively simple configuration, the power supply 4 capable of generating a current in which the excitation current and the demagnetization current are superimposed can be realized. In the path of the demagnetizing current between the demagnetizing current generating unit 42 and the current superposition unit 43, an openable / closable switch may be provided.
The magnetic field control unit 73 that controls such a power supply 4 can switch between a demagnetization mode in which the coil 35 is supplied with a current in which the excitation current and the demagnetization current are superimposed, and a normal mode in which the coil 35 is supplied with the excitation current. It is. Thereby, the second package 36 can be demagnetized at an arbitrary timing.

  In the demagnetization mode, the magnetic field control unit 73 operates the excitation current generation unit 41 and the demagnetization current generation unit 42 simultaneously. More specifically, the magnetic field control unit 73 generates an excitation current, which is a steady current, from the excitation current generation unit 41, and generates a demagnetization current, which is an alternating current that attenuates with time from the demagnetization current generation unit 42. As a result, a current in which the excitation current and the demagnetization current are superimposed is output from the power supply 4. The coil 35 is supplied with a current obtained by superimposing the excitation current and the demagnetizing current from the power supply 4 to generate a demagnetizing magnetic field. As a result, it is possible to generate a demagnetizing magnetic field in which a DC magnetic field component and an AC magnetic field component that attenuates with time are superimposed from the coil 35 configured by one coil.

  In such a demagnetizing magnetic field, the DC magnetic field component and the AC magnetic field component that attenuates with time are superimposed, so the second package 36 is magnetized by the DC magnetic field from the coil 35 by the demagnetizing magnetic field from the coil 35. It is possible to demagnetize in the state in which the same amount of magnetization remains as it is. Therefore, when the excitation magnetic field is generated from the coil 35 after the second package 36 is demagnetized, it is possible to prevent or suppress the temporal change in the amount of magnetization of the second package 36 due to the excitation magnetic field from the coil 35 . As a result, the strength of the magnetic field applied to the alkali metal in the gas cell 31 can be stabilized, and the long-term stability of the frequency can be improved.

  Here, the DC magnetic field component of the demagnetizing magnetic field is based on the excitation current, and the AC magnetic field component of the demagnetizing magnetic field is based on the demagnetizing current. Therefore, the DC magnetic field component of the demagnetizing magnetic field in the second package 36 is equal to or close to the exciting magnetic field. As a result, the amount of magnetization remaining in the second package 36 after demagnetization can be made the same as the amount of magnetization which is magnetized by the DC magnetic field from the coil 35 in the normal mode. Therefore, when the DC magnetic field is generated from the coil 35 in the normal mode after the second package 36 is demagnetized in the demagnetization mode, the change in the amount of magnetization of the second package 36 with time due to the magnetic field from the coil 35 is reduced. It can be (substantially eliminated). The current value of the excitation current in the demagnetization mode is preferably equal to the current value of the excitation current in the normal mode, but if the deviation from the current value of the excitation current in the normal mode is 10% or less, the normal mode It may be different from the current value of the excitation current.

On the other hand, in the normal mode, the magnetic field control unit 73 operates the excitation current generation unit 41 in a state in which the demagnetization current generation unit 42 is stopped. More specifically, the magnetic field control unit 73 generates an excitation current which is a steady state current from the excitation current generation unit 41, and sets the current value of the current generated from the demagnetization current generation unit 42 to zero. That is, when transitioning from the demagnetization mode to the normal mode, the magnetic field control unit 73 stops the demagnetization current generation unit 42 while maintaining the operating state of the excitation current generation unit 41. Thereby, only the excitation current is output from the power supply 4. The coil 35 is supplied with an exciting current from the power supply 4 to generate an exciting magnetic field. As a result, as described above, the alkali metal in the gas cell 31 can be Zeeman-split, and the accuracy of the oscillation frequency of the atomic oscillator 1 can be enhanced.
When a switch that can be opened and closed is provided between the demagnetizing current generation unit 42 and the current superposition unit 43, the operating state of the excitation current generating unit 41 and the demagnetization current generation unit 42 is the same as the demagnetization mode. By opening the switch, the normal mode can be obtained.

Hereinafter, the improvement of the long-term stability of the frequency due to the demagnetization mode as described above will be described more specifically.
FIG. 8 (a) is a graph showing the temporal change of the current flowing through the exciting coil in the conventional demagnetization mode, and FIG. 8 (b) is a transition from the demagnetization mode using the current shown in FIG. 8 (a) to the normal mode It is a graph which shows a time-dependent change of the amount of magnetization of a shield part at the time of having done. 9 (a) is a graph showing temporal changes in current flowing from the power source shown in FIG. 7 to the exciting coil (demagnetizing coil) in the demagnetizing mode, and FIG. 9 (b) is a current shown in FIG. 9 (a) It is a graph which shows a time-dependent change of the amount of magnetizations of a shield part at the time of changing from the demagnetization mode using A to a normal mode. Further, FIG. 10 is a graph showing a modification of the temporal change of the current flowing from the power source shown in FIG. 7 to the exciting coil (demagnetizing coil) in the demagnetizing mode.

In the conventional demagnetization mode, demagnetization is performed using an alternating current in which the current value converges to zero as shown in FIG. If an alternating current as shown in FIG. 8A is supplied to the coil 35 to perform the demagnetization mode, as shown in FIG. 8B, the amount of magnetization of the second package 36 immediately after the end of the demagnetization mode is , Becomes zero. Thereafter, when the mode is switched to the normal mode, the second package 36 is gradually magnetized by the exciting magnetic field from the coil 35. Although this magnetization is stabilized by an amount B1 corresponding to the strength of the excitation magnetic field from the coil 35, it takes a long time from several hours to several months for its stabilization. Therefore, the fluctuation of the magnetization amount of the second package 36 during that period affects the long-term stability of the frequency, and the long-term stability of the frequency decreases.
Although FIG. 8 exemplifies the case where the magnetization of the second package 36 before the start of the demagnetization mode has the same polarity as the magnetization of the second package 36 in the normal mode, the case before the start of the demagnetization mode is illustrated. Also in the case where the magnetization of the second package 36 in the above is opposite in polarity to the magnetization of the second package 36 in the normal mode, the frequency long-term stability is similarly lowered.

On the other hand, in the demagnetization mode according to the present invention, as shown in FIG. 9A, an alternating current is used which converges to a value I1 (in the present embodiment, the current value of the excitation current) different from zero. Therefore, when an alternating current as shown in FIG. 9A is supplied to the coil 35 to perform the demagnetization mode, as shown in FIG. 9B, the amount of magnetization of the second package 36 immediately after the end of the demagnetization mode is , Becomes a value B1 different from zero. This value B1 matches or approximates the amount of magnetization of the second package 36 stabilized by the excitation magnetic field from the coil 35 in the normal mode. Therefore, even after switching to the normal mode after the demagnetization mode, the amount of magnetization of the second package 36 does not fluctuate due to the excitation magnetic field from the coil 35 and is stabilized. That is, in the normal mode, the magnetization amount of the second package 36 can be stabilized immediately after the end of the demagnetization mode.
Because of this, in the atomic oscillator 1, the strength of the magnetic field applied to the alkali metal in the gas cell 31 can be stabilized, and the long-term stability of the frequency can be improved.

  Although FIG. 9 exemplifies a case where the magnetization of the second package 36 before the start of the demagnetization mode has the same polarity as the magnetization of the second package 36 in the normal mode, the state before the start of the demagnetization mode is illustrated. Also in the case where the magnetization of the second package 36 in the above is opposite in polarity to the magnetization of the second package 36 in the normal mode, the long-term stability of the frequency can be similarly improved.

The timing of performing the demagnetization mode as described above is not particularly limited, but, for example, before the oscillation signal of the atomic oscillator 1 is used for a long time. In addition, even after the normal mode is performed once, if the set value of the excitation current is adjustable, the demagnetization mode may be performed after the adjustment. In addition, even after the normal mode has been performed once, the demagnetization mode may be performed when the amount of magnetization of the second package 36 becomes equal to or greater than the predetermined value. The demagnetization mode may be performed every predetermined time regardless of the relationship.
Further, the time length of the demagnetization mode, in other words, the time length from the start of generation of the demagnetization current to the time when the current value becomes zero, is not particularly limited, but is, for example, several seconds to several tens of seconds.

  In addition, before the above-described demagnetization mode, a preliminary demagnetization mode may be performed, which is the same as the conventional demagnetization mode. In this case, as shown in FIG. 10, the power supply 4 outputs an alternating current whose current value converges to zero, and then outputs an alternating current whose current value converges to a value I1 different from zero. As a result, even if the amount of magnetization of the second package 36 is large, the second package 36 can be easily and reliably demagnetized to a desired state. Therefore, the variation in the amount of magnetization of the second package 36 among products can be reduced.

  According to the atomic oscillator 1 of the present embodiment as described above, since the demagnetizing magnetic field is superimposed on the direct current magnetic field component and the alternating magnetic field component which attenuates with time, the second package 36 is generated by the demagnetizing magnetic field from the coil 35. Can be demagnetized in the state in which the same amount of magnetization as the one magnetized by the direct current magnetic field from the coil 35 is left. Therefore, when the excitation magnetic field is generated from the coil 35 after the second package 36 is demagnetized, it is possible to prevent or suppress the temporal change in the amount of magnetization of the second package 36 due to the excitation magnetic field from the coil 35 . As a result, the strength of the magnetic field applied to the alkali metal in the gas cell 31 can be stabilized, and the long-term stability of the frequency can be improved.

Second Embodiment
Next, a second embodiment of the present invention will be described.
FIG. 11 is an enlarged sectional view showing a part of an atomic oscillator according to a second embodiment of the present invention, and FIG. 12 is a block diagram for explaining a magnetic field control unit of the atomic oscillator shown in FIG. FIG. 13 is a graph showing a temporal change of the current flowing from the power supply shown in FIG. 12 to the degaussing coil in the degaussing mode.
The present embodiment is the same as the first embodiment described above except that the degaussing coil is constituted by two coils.

In the following description, the second embodiment will be described focusing on differences from the above-described embodiment, and the description of the same matters will be omitted. Further, in FIG. 11 and FIG. 12, the same components as those of the above-described embodiment are denoted by the same reference numerals.
The atomic oscillator 1A according to the present embodiment is the same as the atomic oscillator 1 according to the first embodiment described above except that the coil 39 is added and the current superimposing unit 43 is omitted.

As shown in FIG. 12, the atomic oscillator 1A shown in FIG. 11 includes a coil 39 and a power supply 4A for supplying current to the coils 35, 39.
The power supply 4A can independently output an excitation current and a demagnetization current.
As shown in FIG. 12, the power supply 4A includes an excitation current generation unit 41 and a demagnetization current generation unit 42.

In the present embodiment, the excitation current generation unit 41 is electrically connected to the coil 35 and supplies the coil 35 with an excitation current. Further, the demagnetizing current generating unit 42 is electrically connected to the coil 39 and supplies the coil 39 with a demagnetizing current.
With such a relatively simple configuration, it is possible to realize the power supply 4A capable of generating a direct current and an alternating current which attenuates with time.

Coil 39 is demagnetizing current from the power source 4A constituting the "ac magnetic field coil" which is supplied to generate an alternating magnetic field component of the degaussing magnetic field. In addition, the coil 35 constitutes a "DC magnetic field coil" which is supplied with an exciting current from the power supply 4A to generate a DC magnetic field component of the demagnetizing magnetic field. By this,
By superimposing the AC magnetic field component from the coil 39 and the DC magnetic field component from the coil 35, a demagnetizing magnetic field can be generated.
By thus generating the demagnetizing magnetic field using the two coils 35 and 39, the freedom of design of the atomic oscillator 1A can be enhanced.

Here, since the coil 35 for generating the excitation magnetic field also serves as a DC magnetic field coil for generating the DC magnetic field component of the demagnetizing magnetic field, the number of parts can be reduced and the miniaturization and cost reduction of the atomic oscillator 1A can be achieved. .
The magnetic field control unit 73 controlling such a power supply 4A can switch between a demagnetization mode in which the coil 35 is supplied with an excitation current and a coil 39 is supplied with a demagnetization current, and a normal mode in which the coil 35 is supplied with an excitation current. It is. Thereby, the second package 36 can be demagnetized at an arbitrary timing.

In the demagnetization mode, the magnetic field control unit 73 operates the excitation current generation unit 41 and the demagnetization current generation unit 42 simultaneously. Thereby, as shown in FIG. 13, the excitation current and the demagnetizing current are simultaneously output from the power supply 4A, and the AC magnetic field component from the coil 39 and the DC magnetic field component from the coil 35 are superimposed to generate a demagnetizing magnetic field. It can be done.
On the other hand, in the normal mode, the magnetic field control unit 73 operates the excitation current generation unit in a state in which the demagnetization current generation unit 42 is stopped. As a result, only the excitation current is output from the power supply 4A, and the coil 35 is supplied with the excitation current from the power supply 4A to generate an excitation magnetic field.

Further, as shown in FIG. 11, the coil 39 is disposed between the second package 36 and the package 5. Thereby, the second package 36 can be miniaturized as compared with the case where the coil 39 is disposed in the second package 36. In addition, when the second package 36 is an airtight package, it is easy to keep the degree of vacuum in the second package 36 high due to the miniaturization. When both the second package 36 and the package 5 have magnetic shielding properties, the magnetic field from the coil 39 can efficiently demagnetize both the second package 36 and the package 5.
In the present embodiment, the coil 39 is composed of a solenoid coil disposed concentrically with the coil 35. Thereby, the coil 39 can be disposed by effectively utilizing the space between the second package 36 and the package 5.

The coil 39 can also be configured by a Helmholtz coil disposed concentrically with the coil 35 and sandwiching the second package 36.
Also according to the second embodiment as described above, it is possible to prevent or suppress the temporal change in the amount of magnetization of the second package 36 due to the magnetic field from the coil 35, and to improve the long-term frequency stability.

2. Electronic Device The atomic oscillator as described above can be incorporated into various electronic devices. Such electronic devices have excellent reliability.
Hereinafter, the electronic device of the present invention will be described.
FIG. 14 is a view showing a schematic configuration when the atomic oscillator of the present invention is used in a positioning system using GPS satellites.
The positioning system 100 shown in FIG. 14 is composed of GPS satellites 200, a base station apparatus 300, and a GPS receiving apparatus 400.

The GPS satellites 200 transmit positioning information (GPS signals).
The base station apparatus 300 receives the positioning information from the GPS satellite 200 with high accuracy via the antenna 301 installed at the electronic reference point (GPS continuous observation station), for example, and the receiving apparatus 302 receives the positioning information And a transmitting device 304 for transmitting positioning information via the antenna 303.

Here, the receiving device 302 is an electronic device provided with the atomic oscillator 1 of the present invention described above as the reference frequency oscillation source. Such a receiver 302 has excellent reliability. Also, the positioning information received by the receiving device 302 is transmitted by the transmitting device 304 in real time.
The GPS receiver 400 includes a satellite receiver 402 which receives positioning information from the GPS satellite 200 via the antenna 401, and a base station receiver 404 which receives positioning information from the base station 300 via the antenna 403. Prepare.

3. Mobile Object FIG. 15 is a view showing an example of a mobile object provided with the atomic oscillator of the present invention.
In this figure, the moving body 1500 has a vehicle body 1501 and four wheels 1502, and is configured to rotate the wheels 1502 by a power source (engine) (not shown) provided on the vehicle body 1501. The atomic oscillator 1 is built in such a mobile unit 1500.
According to such a mobile unit, excellent reliability can be exhibited.

The electronic apparatus provided with the atomic oscillator of the present invention is not limited to the above-mentioned ones, and, for example, mobile phones, digital still cameras, inkjet discharge devices (eg, inkjet printers), personal computers (mobile personal computers, laptops) Type personal computers), TVs, video cameras, video tape recorders, car navigation devices, pagers, electronic organizers (including communication functions), electronic dictionaries, calculators, electronic game devices, word processors, workstations, video phones, television for crime prevention Monitors, electronic binoculars, POS terminals, medical devices (such as electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasound diagnostic devices, electronic endoscopes), fish finders, various measuring devices, instruments (such as vehicles ,aircraft, Instruments of 舶), can be applied to a flight simulator or the like.
The atomic resonance transition device, the atomic oscillator, the electronic device, and the moving body according to the present invention have been described above based on the illustrated embodiments, but the present invention is not limited to these.
Moreover, this invention can be substituted to the thing of arbitrary structures which exhibit the same function of embodiment mentioned above, and can also add arbitrary structures.

Furthermore, in the present invention, arbitrary configurations of the above-described embodiments may be combined.
In the embodiment described above, the case where the light emitting portion and the gas cell are housed in separate packages has been described as an example, but the light emitting portion, the gas cell, the light detecting portion and the like are the same package (shielding portion or inner shielding May be stored in the

Further, in the embodiment described above, the excitation current is used as the direct current for obtaining the DC magnetic field component of the demagnetizing magnetic field, but a DC current from a power supply different from the excitation current may be used. In this case, it is preferable that the direct current for obtaining the direct current magnetic field component of the demagnetizing magnetic field has the same direction as the excitation current, and be in agreement with or close to the current value of the excitation current.
In the above-described embodiment, the quantum interference device for performing resonance transition of cesium or the like by utilizing the quantum interference effect of two types of light having different wavelengths has been described as an example of the atomic resonance transition device of the present invention. The atomic resonance transition device is not limited to this, and is also applicable to a double resonance device that causes rubidium or the like to make a resonance transition using double resonance phenomenon by light and microwave.

1. Atomic oscillator 1A Atomic oscillator 2. First unit 3. Second unit 4. Power supply 4A. Power supply 5. Package 6. Wiring board 7. Control part 21. Light emitting part 22 Package 1 23. Window 31. Gas cell 32. Light detector 33. Heater 34. Temperature sensor 35. Coil 36. Package 2 37. Window 38. Substrate 37 ... coil 41 ... excitation current generation unit 42 ... demagnetization current generation unit 43 ... current superposition unit 50 ... main body 51 ... recess 52 ... support unit 53 ... support unit 54 ... lid 61 ... ... penetration Bore 62 .. Terminal 63 .. Terminal 71 .. Excitation light control unit 72 .. Temperature control unit 73 .. Magnetic field control unit 100 .. Positioning system 200 .. Satellite 221 .. Base body 222 .. Lid 22 .. Terminal 300. Base station device 301. Antenna 302. Reception device 303. Antenna 304. Transmission device 311. Body portion 312. Window portion 313. Window portion 331 .. Heating resistor 332 .. .. Heating element 361 ... Base body 362 ... Lid body 363 ... Terminal 400 ... Reception device 401 ... Antenna 402 ... Satellite reception section 403 ... Antenna 404 ... Base station reception section 521 ... Through hole 531 .. .. Through hole 1500 .. Moving body 1501 .. Car body 1502 .. Wheel a .. Optical axis LL .. Excitation light S .... Interior space S1 .... Interior space

Claims (5)

With metal atoms,
A gas cell enclosing the metal atom;
A shielding portion having magnetic shielding properties and containing the gas cell ;
A power supply capable of generating a DC current and an alternating current which attenuates with time independently and simultaneously;
And Koban magnetic field coil for generating the alternating current is supplied ac magnetic field component from the power supply,
Anda DC magnetic field coils for generating the DC current is supplied direct current magnetic field component from the power supply,
Wherein the degauss mode demagnetizing the shield portion, prior SL is supplied to the DC current the DC magnetic field coil, the alternating current is supplied to the alternating magnetic field coil, and the DC magnetic field component magnetizing front Symbol shielding portion, the degaussing magnetic field and the alternating magnetic field components to attenuate the shielding portion demagnetized over time, it is superimposed is generated,
In the normal mode different from the demagnetization mode, the DC current is supplied to the DC magnetic field coil, and an excitation magnetic field including the DC magnetic field component applied to the metal atoms is generated.
The shielding part includes an inner shielding part and an outer shielding part which are disposed inside and outside;
The DC magnetic field coil is disposed around the gas cell and between the metal atom and the inner shield.
The Koban field coil is atomic resonance transition apparatus characterized by being arranged between the inner shield part and the outer shield part. It has a magnetic field control unit that controls the power supply,
The atomic resonance transition apparatus according to claim 1, wherein the magnetic field control unit is capable of switching the power supply between the demagnetization mode and the normal mode. Atomic oscillator, characterized in that it comprises an atomic resonance transition device according to claim 1 or 2. An electronic apparatus, comprising the atomic resonance transition device according to claim 1 or 2. Mobile, characterized in that it comprises an atomic resonance transition device according to claim 1 or 2.

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