Miniature physical system of chip atomic clock

Abstract

The utility model relates to the technical field of chip atomic clocks, particularly provides a micro physical system of a chip atomic clock, and aims to solve the problem that the light transmittance is affected due to the fact that a light-transmitting window of an air chamber of a chip atomic clock in the prior art is easy to pollute. In order to achieve the purpose, the miniature physical system comprises a shielding unit, a magnetic field assembly, a vacuum unit and a center assembly, and the shielding unit is provided with a shielding cavity; the magnetic field assembly sleeves the vacuum unit, and the vacuum unit is provided with a vacuum cavity; the center assembly is arranged in the vacuum cavity and comprises a heating piece, a heat transfer cylinder and an air chamber which are sequentially stacked, a receding notch is formed in the side wall of the heat transfer cylinder, and at least part of the air chamber is arranged outside the heat transfer cylinder through the receding notch. By means of the scheme, steam in the air chamber can be condensed in the air chamber outside the cylinder, the light-transmitting area of the air chamber is avoided, and the problem that the light transmittance is affected due to the fact that the steam is condensed on the light-transmitting face of the air chamber is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of chip atomic clocks, and specifically provides a micro-physical system of a chip atomic clock. Background Art

[0002] Time measurement is one of the basic tools in modern society and has important applications in precision measurement, satellite navigation and other fields. There is an energy level system inside the atom that is not easily disturbed by the outside world. The atomic clock synchronizes the frequency of the oscillation source with the atomic energy level to achieve better long-term stability. The size, power consumption and cost of traditional atomic clocks are very large, which limits the terminal application scenarios. The miniaturization, low power consumption and simple production of chip atomic clocks make up for the above shortcomings.

[0003] The rubidium in the MEMS atomic gas chamber in the current chip atomic clock will gradually condense on the light-transmitting surface at high temperatures, blocking the light-transmitting window and affecting the light transmittance of the atomic gas chamber, thereby causing fluctuations and drifts in the atomic absorption spectrum, affecting the frequency stability and frequency drift of the atomic clock.

[0004] Based on the above problems, accordingly, the art needs a new atomic clock structure to solve the above problems. Utility Model Content

[0005] The utility model aims to solve the above technical problem, that is, to solve the problem in the prior art that the light-transmitting window of the gas chamber of the chip atomic clock is easily contaminated and thus affects the light transmittance.

[0006] In a first aspect, the utility model provides a micro-physical system of a chip atomic clock, the micro-physical system comprising:

[0007] A shielding unit, wherein the shielding unit is provided with a shielding cavity;

[0008] A magnetic field assembly and a vacuum unit, wherein the magnetic field assembly is sleeved on the vacuum unit, and the vacuum unit is provided with a vacuum cavity;

[0009] A central component is arranged in the vacuum chamber, and the central component includes a heating plate, a heat transfer tube and an air chamber stacked in sequence. The side wall of the heat transfer tube is provided with a clearance gap, and the air chamber is at least partially arranged outside the heat transfer tube through the clearance gap.

[0010] In a specific embodiment of a micro-physical system having the above-mentioned chip atomic clock, a fixed area, a hollow area and a heating area are provided on the heating plate, the hollow area is between the heating area and the fixed area, a plurality of cantilever beams are provided in the hollow area for connecting the fixed area and the heating area, and the heating area is a centrally symmetrical structure.

[0011] In a specific embodiment of the microphysical system with the above-mentioned chip atomic clock, the central component further includes a heat-conducting metal strip, a thermistor, and a micro-heater. A plurality of micro-heaters are arranged on one side surface of the heating area, the heat-conducting metal strip is arranged on the other side surface of the heating area, the heat-conducting metal strip is connected end to end to form a closed structure, and the thermistor is arranged on the same side as the heat-conducting metal strip and inside the closed heat-conducting metal strip.

[0012] In a specific embodiment of the microphysical system with the above-mentioned chip atomic clock, the central component further includes a laser and a glass slide. The laser is arranged on the heating area and on the same side as the heat-conducting metal strip, and the glass slide is arranged between the gas chamber and the heating sheet.

[0013] In a specific embodiment of the microphysical system with the above-mentioned chip atomic clock, the central component further includes a detector circuit board. The detector circuit board is arranged on the heat transfer cylinder, and the glass slide, the gas chamber, and the detector circuit board are arranged in sequence. A photodiode is arranged on the detector circuit board.

[0014] In a specific embodiment of the microphysical system with the above-mentioned chip atomic clock, the vacuum unit includes a ceramic cap and a carrier base plate, and the ceramic cap is welded to the carrier base plate.

[0015] In a specific embodiment of the microphysical system with the above-mentioned chip atomic clock, a plurality of pads are arranged in the fixed area, and the heating sheet is connected to the carrier base plate by means of the pads.

[0016] In a specific embodiment of the microphysical system with the above-mentioned chip atomic clock, the detector circuit board is connected to the carrier base plate by a bonding wire, and the carrier base plate is provided with output pins.

[0017] In a specific embodiment of the microphysical system with the above-mentioned chip atomic clock, the magnetic field component includes a coil bracket and a winding coil. The winding coil is arranged on the coil bracket, the coil bracket is provided with a through hole, and the vacuum unit is arranged in the through hole.

[0018] In a specific embodiment of the microphysical system with the above-mentioned chip atomic clock, the shielding unit includes a shielding housing and a shielding base, and the shielding housing is arranged on the shielding base to form the shielding cavity.

[0019] In the case of adopting the above-mentioned technical scheme, the micro-physical system of the chip atomic clock proposed by the utility model adopts a heat transfer tube with a clearance gap, and the air chamber installed in the heat transfer tube is at least partially located outside the heat transfer tube. The heat of the heating plate is transferred to the air chamber through the heat transfer tube, and the heat is mainly concentrated on the cylinder body of the heat transfer tube. The temperature of the air chamber inside the heat transfer tube is higher than the temperature outside the tube. Therefore, the steam in the air chamber will condense in the part of the air chamber outside the tube, avoiding the light-transmitting area of ​​the air chamber, eliminating the problem of steam condensing on the light-transmitting surface of the air chamber and affecting the transmittance, thereby solving both the problem of light transmittance of the air chamber and the problem of slow migration of atoms in the air chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0021] Figure 1 It is an overall exploded diagram of the micro physical system in the utility model;

[0022] Figure 2 It is an exploded view of the central component of the micro-physical system in the utility model;

[0023] Figure 3 This is a schematic diagram of the front structure of the heating plate of the micro-physical system in the utility model;

[0024] Figure 4 It is a schematic diagram of the back structure of the heating plate of the micro-physical system in the utility model.

[0025] Among them, 1. shielding unit, 2. magnetic field component, 3. vacuum unit, 4. central component, 5. heating plate, 6. heat transfer tube, 7. air chamber, 8. clearance gap, 9. fixing area, 10. hollow area, 11. heating area, 12. cantilever beam, 13. thermal conductive metal belt, 14. thermistor, 15. micro heater, 16. laser, 17. glass slide, 18. detector circuit board, 19. photodiode, 20. ceramic cap, 21. carrier base plate, 22. soldering pad, 23. coil bracket, 24. coil assembly, 25. shielding shell, 26. shielding base. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not used to limit the protection scope of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0027] It should be noted that in the description of the present utility model, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the drawings. This is only for convenience of description and does not indicate or imply that the relevant devices or components must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In addition, ordinal numbers such as "first", "second", etc. are only for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0028] In addition, it should also be noted that in the description of the present utility model, unless otherwise clearly specified and defined, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0029] As Figures 1-4 shown, the present utility model provides a microphysical system of a chip atomic clock. The microphysical system includes: a shielding unit 1, a magnetic field component 2, a vacuum unit 3, and a central component 4. The shielding unit 1 is provided with a shielding cavity; the magnetic field component 2 is sleeved on the vacuum unit 3, and the vacuum unit 3 is provided with a vacuum cavity; the central component 4 is arranged in the vacuum cavity. The central component 4 includes a heating sheet 5, a heat transfer cylinder 6, and a gas chamber 7 that are sequentially stacked. A relief notch 8 is provided on the side wall of the heat transfer cylinder 6, and at least a part of the gas chamber 7 is arranged outside the heat transfer cylinder 6 through the relief notch 8.

[0030] In this embodiment, the proposed microphysical system of the chip atomic clock mainly consists of a shielding unit 1, a magnetic field component 2, a vacuum unit 3, and a central component 4. The inside of the shielding unit 1 is a hollow shielding cavity. The magnetic field component 2, the vacuum unit 3, and the central component 4 are all arranged in the shielding cavity. The shielding unit 1 is used to shield the static magnetic field in the environment, especially the earth's magnetic field. The central component 4 is installed in the vacuum cavity of the vacuum unit 3. The magnetic field component 2 is sleeved on the vacuum unit 3. The magnetic field component 2 provides a resonant magnetic field for the central component 4. The inside of the central component 4 is a vacuum environment, providing a working environment for the central component 4. The central component 4 works in a vacuum environment. Among them, the heating sheet 5 heats up to raise the temperature of the heat transfer cylinder 6, and a part of the gas chamber 7 located inside the heat transfer cylinder 6 is synchronously heated. The gas chamber 7 is filled with rubidium / cesium elements and buffer gas, and steam will be formed as the temperature rises, and an atomic absorption spectrum signal will be output under certain working conditions.

[0031] In the above embodiment, the structure of the heat transfer cylinder 6 is optimized by providing a relief notch 8 on the side wall, so that a part of the gas chamber 7 installed in the heat transfer cylinder 6 is inside the cylinder and a part is outside the cylinder. The temperature of the gas chamber 7 inside the cylinder is high, and the temperature of the gas chamber 7 outside the cylinder is low. The formed steam will condense outside the cylinder, and the part inside the cylinder that participates in the work and outputs the atomic absorption spectrum signal will not have its light transmittance reduced due to condensation on the side wall. Therefore, the problem of the light transmittance of the gas chamber 7 and the problem of slow atomic migration in the gas chamber 7 are both solved. It should be noted that the relief notch 8 on the side wall of the heat transfer cylinder 6 can exemplarily adopt an arc groove structure with an opening, but this is not restrictive. The shape and setting area of the relief notch 8 are optional, as long as the structure that enables part of the gas chamber 7 to be outside the cylinder can be satisfied.

[0032] On the basis of the above embodiment, the heating sheet 5 is divided into a fixed area 9, a hollow area 10 and a heating area 11. The heating sheet 5 can be made of, but is not limited to, a ceramic sheet. Among them, the hollow area 10 is between the fixed area 9 and the heating area 11, and the fixed area 9 and the heating area 11 are connected by a cantilever beam 12. Among them, the heating area 11 is a centrosymmetric structure, so that the heat can be more evenly distributed. It should be noted that the shape, quantity and area of the hollow area 10 are not restrictive. At the same time, the number, shape and distribution of the cantilever beams 12 can also be designed as needed.

[0033] Considering the power consumption of the atomic clock, the existing process uses a copper-plated polyimide film. This method can reduce the power consumption, but the mechanical strength is weak, which does not meet the anti-vibration requirements of the atomic clock. However, the heating sheet 5 adopted in this embodiment, by designing a hollow structure and optimizing the symmetry of the heating area 11, minimizes heat conduction and reduces heat loss. The centrosymmetry of the heating area 11 makes the temperature of the disc boundary uniform, and can efficiently utilize heat while reducing power consumption. In addition, the hollow area 10 is also provided with a cantilever beam 12 structure, which can meet the anti-vibration requirements of the atomic clock and improve the mechanical strength.

[0034] On the basis of the above embodiment, a micro-heater 15 is installed on one side of the heating area 11, and a heat-conducting metal strip 13 and a thermistor 14 are installed on the other side. Among them, multiple micro-heaters 15 can be provided, and the distribution is centered symmetrically. The heat-conducting metal strip 13 is connected end to end to form a closed structure, so that the temperature distribution of the heating area 11 is more uniform. A thermistor 14 is installed in the inner area of the closed heat-conducting metal strip 13, so as to obtain the heating temperature and accurately control the temperature.

[0035] In a conceivable embodiment, four micro-heaters 15 are provided and arranged in a square area in the heating area 11. The heat-conducting metal strip 13 is made of a circular copper sheet. Of course, the above embodiment is only exemplary, and the number of micro-heaters 15, the material and arrangement of the heat-conducting metal strip 13 can all be selected according to actual needs.

[0036] In the prior art, the solutions of plating heating films or heating wires on ceramic substrates or polyimide films are mostly adopted, and the copper plating process requires complex processes such as plating masks, lithography, copper plating, and mask removal. The utility model of this patent optimizes the heat distribution by welding micro heaters and designing a thermally conductive metal strip 13 with a closed structure, so as to achieve the effect of heating films or heating wires, but the processing and production processes are simpler and the cost is lower.

[0037] On the basis of the above embodiments, a laser 16 is further provided on the heating area 11. The laser 16 is installed on the same side as the thermally conductive metal strip 13. The glass sheet 17 is supported by the gas chamber 7 and the heating sheet 5. Among them, the optical axis direction of the glass sheet 17 forms a 45° angle with the laser polarization direction, and is used to convert linearly polarized laser into circularly polarized laser. The laser 16 can adopt a VCSEL bare core.

[0038] It should be noted that the back pads 22 of the laser 16, the thermistor 14 and the micro heater 15 are bonded to the heating sheet 5, and the bonding adhesive adopts a metal adhesive (such as silver adhesive to ensure no outgassing characteristics); the front pads 22 of the laser 16, the thermistor 14 and the micro heater 15 are connected to the pads 22 of the heating sheet 5 through gold wire bonding. For the parts related to dispensing in the embodiments, it is ensured that there is no outgassing characteristic.

[0039] On the basis of the above embodiments, the central component 4 further includes a detector circuit board 18. The detector circuit board can adopt a PD substrate, and a photodiode 19 is installed on it to detect the atomic absorption spectrum signal.

[0040] The detector circuit board 18 is installed on the heat transfer cylinder 6. When installing, the top end face of the heat transfer cylinder 6 is dispensed with glue, and the detector circuit board 18 is baked and cured. The gas chamber 7 in the heat transfer cylinder 6 is also filled with glue with a suitable concentration to eliminate gaps.

[0041] On the basis of the above embodiments, the vacuum unit 3 adopts a combination of a ceramic cap 20 and a carrier base plate 21. Among them, the carrier base plate 21 can adopt an LCC base. A plurality of pads 22 are provided in the fixing area 9 of the heating sheet 5, and the heating sheet 5 is connected to the carrier base plate 21 through dispensing and baking curing of the pads 22.

[0042] The connection between the ceramic cap 20 and the carrier base plate 21 especially considers the sealing performance, because the life of the atomic clock mainly depends on the air leakage rate of the atomic gas chamber 7. The air leakage rate of the MEMS atomic gas chamber 7 produced by the anodic bonding process can no longer meet the customer's demand for long life; in this embodiment, an In-Au solder is placed at the interface between the ceramic cap 20 and the carrier base, and placed in a eutectic bonding device. The device needs to be evacuated, the vacuum degree is within 1 Pa, and the temperature is within 260 °C; a vacuum sealing structure is formed by eutectic bonding. By adopting the above vacuum structure, the service life of the vacuum gas chamber 7 can be extended.

[0043] On the basis of the above embodiments, the detector circuit board 18 is connected to the carrier base plate 21 by bonding wires to form data transmission, and the output pins on the carrier base plate 21 export the data for analysis.

[0044] On the basis of the above embodiments, the magnetic field assembly 2 provides a magnetic field by installing a winding coil 24 on a coil bracket 23. The center of the coil bracket 23 is a through hole, and the vacuum unit 3 is located in the through hole and cooperates with the magnetic field formed by the magnetic field assembly 2.

[0045] On the basis of the above embodiments, the shielding unit 1 is a structure combined by a shielding shell 25 and a shielding base 26. After being buckled, a shielding cavity is formed to shield the magnetic field of the environment, especially the earth's magnetic field.

[0046] All components in the above embodiments can be formed in one time by mature processes, and the whole installation process does not involve complex processes and equipment. Moreover, the whole process only has vertical assembly, which is very suitable for automated production and improves production efficiency.

[0047] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A micro-physical system of a chip atomic clock, characterized in that: The micro-physical system comprises: A shielding unit (1), wherein the shielding unit (1) is provided with a shielding cavity; A magnetic field component (2) and a vacuum unit (3), wherein the magnetic field component (2) is sleeved on the vacuum unit (3), and the vacuum unit (3) is provided with a vacuum chamber; A central component (4), the central component (4) is arranged in the vacuum chamber, the central component comprises a heating plate (5), a heat transfer tube (6) and an air chamber (7) which are stacked in sequence, the side wall of the heat transfer tube (6) is provided with a clearance gap (8), and the air chamber (7) is at least partially arranged outside the heat transfer tube (6) through the clearance gap (8).

2. The micro-physical system of the chip atomic clock according to claim 1, characterized in that: The heating plate (5) is provided with a fixed area (9), a hollow area (10) and a heating area (11); the hollow area (10) is between the heating area (11) and the fixed area (9); the hollow area (10) is provided with a plurality of cantilever beams (12) for connecting the fixed area (9) and the heating area (11); and the heating area (11) is a centrally symmetrical structure.

3. The micro-physical system of the chip atomic clock according to claim 2, characterized in that: The central component (4) further comprises a heat-conducting metal belt (13), a thermistor (14) and a micro-heater (15); a plurality of micro-heaters (15) are arranged on one side of the heating zone (11); the heat-conducting metal belt (13) is arranged on the other side of the heating zone (11); the heat-conducting metal belt (13) is connected end to end to form a closed structure; the thermistor (14) is arranged on the same side as the heat-conducting metal belt (13) and is located on the inner side of the closed heat-conducting metal belt (13).

4. The micro-physical system of the chip atomic clock according to claim 3, characterized in that: The central component (4) further comprises a laser (16) and a glass slide (17), wherein the laser (16) is arranged on the heating zone (11) and is located on the same side as the heat-conducting metal belt (13), and the glass slide (17) is arranged between the gas chamber (7) and the heating plate (5).

5. The micro-physical system of the chip atomic clock according to claim 4, characterized in that: The central component (4) further comprises a detector circuit board (18), wherein the detector circuit board (18) is arranged on the heat transfer tube (6), the glass slide (17), the gas chamber (7) and the detector circuit board (18) are arranged in sequence, and a photodiode (19) is arranged on the detector circuit board (18).

6. The micro-physical system of the chip atomic clock according to claim 5, characterized in that: The vacuum unit (3) comprises a ceramic cap (20) and a carrier base plate (21), and the ceramic cap (20) is welded to the carrier base plate (21).

7. The micro-physical system of the chip atomic clock according to claim 6, characterized in that: The fixing area (9) is provided with a plurality of solder pads (22), and the heating plate (5) is connected to the carrier bottom plate (21) by means of the solder pads (22).

8. The micro-physical system of a chip atomic clock according to claim 6, characterized in that: The detector circuit board (18) and the carrier base plate (21) are connected by bonding gold wires, and the carrier base plate (21) is provided with output pins.

9. The micro-physical system of a chip atomic clock according to any one of claims 1 to 8, characterized in that: The magnetic field component (2) comprises a coil support (23) and a winding coil (24); the winding coil (24) is arranged on the coil support (23); the coil support (23) is provided with a through hole; and the vacuum unit (3) is arranged in the through hole.

10. The micro-physical system of the chip atomic clock according to claim 9, characterized in that: The shielding unit (1) comprises a shielding shell (25) and a shielding base (26); the shielding shell (25) is arranged on the shielding base (26) to form the shielding cavity.

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