PCB (Printed Circuit Board) test equipment for various radio frequency ports

Abstract

The invention discloses PCB test equipment for various radio frequency ports, which comprises a main supporting assembly, a main mounting assembly is arranged on the main supporting assembly, a PCB transverse moving assembly is arranged on the main mounting assembly, and PCB test upper die mechanisms are arranged on two sides of the PCB transverse moving assembly on the main mounting assembly. A static elimination device is arranged on the main installation assembly and located on one side of one PCB test upper die mechanism, a circulator press-fit test mechanism is arranged on the main installation assembly and located on one side of the static elimination device, and a circulator feeding and discharging bin is arranged on the main installation assembly and located on one side of the circulator press-fit test mechanism. An auxiliary supporting assembly is arranged on the main mounting assembly and located on one side of the circulator feeding and discharging bin, a feeding visual system is arranged on the auxiliary supporting assembly, and an auxiliary carrying assembly is arranged on the main supporting assembly. The PCB test equipment has the beneficial effects that the automatic test of various radio frequency ports on the PCB is realized by applying the PCB test equipment, the test efficiency is effectively improved, and the test precision is also improved.

Description

Technical Field

[0001] The invention relates to the technical field of PCB testing, in particular to a PCB testing device for multiple radio frequency ports. Background Art

[0002] The purpose of PCB testing and inspection is to check whether the PCB meets the performance of standard printed circuit boards and ensure that all PCB manufacturing processes are running properly according to project specifications without any defects. A PCB is composed of different elements and components. Each element will affect the overall performance of the electronic circuit. These components must be analyzed in detail to ensure the quality of the PCB. The tests to be performed should include the following checks: Lamination. The quality of lamination is crucial to the service life of the PCB. Laminate peeling will directly cause problems in the function of the circuit board. Normally, lamination testing is used to test the resistance of the laminate to peeling due to force or heat.

[0003] In PCB design, the design and processing of RF ports is a key link. They involve the reception, transmission and processing of signals, which is crucial to ensure the performance and function of electronic equipment. RF ports mainly include RF front-end circuits, RF transmission lines, RF power amplifiers, and RF mixers. Each component has its specific design and processing requirements. The RF ports on PCB also include a variety of connectors, such as USB ports, Lightning ports, HDMI ports, etc. These interfaces use a unified protocol standard to achieve indiscriminate interaction between devices. The naming of RF coaxial connectors consists of the main code and the structure code, which is easy to identify and use.

[0004] In summary, the design and selection of various RF ports and connectors on PCB directly affect the performance and function realization of electronic equipment. Through reasonable layout and optimized design, the RF performance of the equipment can be significantly improved to meet the needs of various application scenarios.

[0005] Various RF ports on PCB need to be tested. Existing test equipment is inconvenient to operate, has single function, poor test stability, low test efficiency, and cannot meet the test requirements of RF ports. Therefore, a PCB test equipment for various RF ports is designed. Summary of the invention

[0006] The purpose of the present invention is to solve the above problems and to design a PCB testing device for multiple radio frequency ports.

[0007] To achieve the above-mentioned purpose, the technical solution of the present invention is a PCB testing device for multiple radio frequency ports, comprising a main support assembly, a main mounting assembly is arranged on the main support assembly, a PCB lateral movement assembly is arranged on the main mounting assembly, a PCB test upper mold mechanism is arranged on both sides of the PCB lateral movement assembly on the main mounting assembly, an electrostatic eliminator is arranged on one side of one of the PCB test upper mold mechanisms on the main mounting assembly, a circulator pressing test mechanism is arranged on the main mounting assembly on one side of the electrostatic eliminator, a circulator upper and lower material bins are arranged on the main mounting assembly on one side of the circulator pressing test mechanism, an auxiliary support assembly is arranged on the main mounting assembly on one side of the circulator upper and lower material bins, a loading visual system is arranged on the auxiliary support assembly, and an auxiliary transport assembly is arranged on the main support assembly.

[0008] As a further description of the technical solution, the main support assembly includes a main support frame, a main mounting assembly is arranged on the main support frame, and a plurality of balance adjustment feet are arranged at the bottom of the main support frame.

[0009] As a further description of the technical solution, the main mounting assembly includes a main mounting plate arranged on the main support assembly, and a PCB lateral movement assembly is arranged on the main mounting plate.

[0010] As a further description of the technical solution, the PCB transverse movement assembly includes a PCB transverse movement conveying module arranged on the main installation assembly, the moving part of the PCB transverse movement conveying module is provided with a moving plate, the moving plate is provided with a jacking assembly, the jacking assembly is provided with a test lower mold carrier plate, and the test lower mold carrier plate is provided with a plurality of support columns.

[0011] As a further description of the technical solution, the PCB test upper mold mechanism includes a support frame arranged on the main support assembly and located on both sides of the PCB transverse movement assembly, an upper template is arranged on the support frame, a plurality of SMP RF connector adaptive components are arranged on the upper template, and a plurality of elastic rods are arranged on the upper template.

[0012] As a further description of the technical solution, a fiber optic test needle mold assembly is arranged on one side of the SMP RF connector adaptive assembly on the upper template, and a low-frequency test needle mold assembly is arranged on one side of the fiber optic test needle mold assembly on the upper template.

[0013] As a further description of the technical solution, the upper and lower material bins of the annular device include a full bin, an empty pan bin, an OK bin, and an NG bin arranged on the main mounting assembly. The bottom of the full bin, the empty pan bin, the OK bin, and the NG bin are all provided with a lifting module, and a sensor is provided on one side of the full bin.

[0014] As a further description of the technical solution, the auxiliary support assembly includes an auxiliary support frame arranged on the main mounting assembly and located on one side of the upper and lower material bins of the annular device, and the auxiliary support frame is provided with a loading vision system, and the loading vision system includes a photo positioning camera arranged on the auxiliary support frame.

[0015] As a further description of the technical solution, the auxiliary transport component includes an auxiliary transport robot arranged on the main installation component and located on one side of the auxiliary support component. The output end of the auxiliary transport robot is provided with a transport suction cup, and the transport suction cup is provided with an identification camera.

[0016] A working method of a PCB testing device for multiple radio frequency ports comprises the following steps: multiple radio frequency port tests, a photo positioning camera takes a photo positioning of a PCB board, then an auxiliary transport manipulator drives a transport suction cup to grab the PCB board, a recognition camera on the transport suction cup recognizes a character QR code on the PCB board and transmits a system record, the auxiliary transport manipulator moves the recognized PCB board to a test lower mold carrier, the recognition camera sequentially takes photos and detects an SMP radio frequency port and an optical fiber port on the PCB board, after the detection is completed, the auxiliary transport manipulator transports another PCB board to another test lower mold carrier, the recognition camera sequentially takes photos and detects the SMP radio frequency port and the optical fiber port on the second transported PCB board, after completion, the PCB transverse conveying module drives the test lower mold carrier to move to the bottom of the upper mold plate, the lifting assembly drives the test lower mold carrier to lift, and the PCB board first contacts the installation Dozens of elastic rods on the upper template gradually press the PCB board as the test lower mold carrier rises, and then the SMP RF port is inserted into the SMP RF connector adaptive component. At the same time, the optical port test solder joints of the PCB board contact the optical fiber test needle mold component, and the low-frequency test port test points contact the low-frequency test needle mold component. The test lower mold carrier rises to the height set by pre-debugging. The cylinder of the low-frequency test needle mold component recycles the low-frequency probes and contacts the test points respectively, so that each test point is fully contacted to start the test. After the test is completed, the cylinder of the low-frequency test needle mold component extends to separate the low-frequency probe from the test point, and the test lower template descends. During the descent, the elastic force of the elastic rods is used to separate the SMP RF port from the SMP RF connector and descend to the initial position. The PCB transverse conveying module drives the tested PCB board back to the loading and unloading position, and the auxiliary handling robot unloads the tested PCB board to the unloading docking station.

[0017] When testing the circulator, the auxiliary handling robot places the circulator in the circulator test fixture of the circulator pressing test mechanism, and takes a photo of the circulator through the recognition camera for detection. After the detection, the circulator pressing test mechanism presses down the circulator to start the test. During the test, after the test is completed, the auxiliary handling robot picks up the tested products and places the tested products in the OK or NG bin according to the test results. The auxiliary handling robot puts the material in the full bin into the circulator test fixture, takes a photo again to detect whether it is placed in place, and then conducts the test. Then, if the entire tray of material in the full bin has been tested, the auxiliary handling robot absorbs the empty tray and places it in the empty tray bin. The full bin position sensor detects that the upper tray is taken away, and the lifting module under the bin will raise the lower tray to the original material picking height, thereby repeatedly realizing the automatic clamping, automatic loading and unloading, automatic sorting, and automatic pressing test of the circulator.

[0018] The beneficial effect lies in that the PCB test equipment of the technical solution has an ingenious structural design, strong practicality, and stable operation. By using this PCB test equipment, automatic testing of various RF ports on the PCB board is realized. At the same time, automatic testing of the circulator is also realized, which effectively improves the test efficiency and the test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 It is a structural schematic diagram of the PCB lateral movement assembly of the present invention;

[0021] Figure 3 It is a structural schematic diagram of the PCB test upper mold mechanism of the present invention;

[0022] Figure 4 It is a structural schematic diagram of the upper and lower bins of the annular device of the present invention.

[0023] In the figure, 1. Main support assembly; 2. Main installation assembly; 3. PCB transverse movement assembly; 4. PCB test upper mold mechanism; 5. Static elimination device; 6. Circulator pressing test mechanism; 7. Circulator upper and lower bins; 8. Auxiliary support assembly; 9. Loading vision system; 10. Auxiliary handling assembly; 11. Main support frame; 12. Balance adjustment foot; 13. Main installation plate; 14. PCB transverse movement conveying module; 15. Moving plate; 16. Lifting assembly; 17. Test lower mold carrier plate; 19. Support frame; 20. Upper template; 21. SMP RF connector adaptive assembly; 23. Optical fiber test needle mold assembly; 24. Low frequency test needle mold assembly; 25. Full bin; 26. Empty bin; 27. OK bin; 28. NG bin; 29. ​​Lifting module; 31. Auxiliary support frame; 32. Photo positioning camera; 33. Auxiliary handling manipulator; 34. Handling suction cup. DETAILED DESCRIPTION

[0024] First of all, the design intention of the present invention is explained. Various radio frequency ports on a PCB board need to be tested. Existing testing equipment is inconvenient to operate, has a single function, poor test stability, and low test efficiency, and cannot meet the testing requirements of the radio frequency ports. Therefore, the present invention designs a PCB testing device for multiple radio frequency ports.

[0025] The present invention will be described in detail below in conjunction with the accompanying drawings. Figure 1-Figure 4 As shown, a PCB testing device for multiple radio frequency ports includes a main support component 1. The main support component 1 will be described in detail below. The main support component 1 includes a main support frame 11, a main mounting component 2 is arranged on the main support frame 11, and a plurality of balance adjustment feet 12 are arranged at the bottom of the main support frame 11.

[0026] In order to facilitate the installation of the PCB transverse shifting assembly 3, a main mounting assembly 2 is arranged on the main supporting assembly 1. The main mounting assembly 2 will be described in detail below. The main mounting assembly 2 includes a main mounting plate 13 arranged on the main supporting assembly 1, and the main mounting plate 13 is provided with the PCB transverse shifting assembly 3.

[0027] In order to facilitate the movement control of the test lower mold carrier plate 17, a PCB transverse movement component 3 is arranged on the main installation component 2. The PCB transverse movement component 3 will be described in detail below. The PCB transverse movement component 3 includes a PCB transverse movement conveying module 14 arranged on the main installation component 2, and a moving plate 15 is arranged at the moving part of the PCB transverse movement conveying module 14. A lifting component 16 is arranged on the moving plate 15, and a test lower mold carrier plate 17 is arranged on the lifting component 16. The test lower mold carrier plate 17 is provided with a plurality of support columns.

[0028] An optical fiber test needle mold assembly 23 is arranged on the upper template 20 at one side of the SMP RF connector adaptive assembly 21 , and a low-frequency test needle mold assembly 24 is arranged on the upper template 20 at one side of the optical fiber test needle mold assembly 23 .

[0029] In order to facilitate PCB testing, a PCB test upper mold mechanism 4 is arranged on both sides of the PCB transverse movement component 3 on the main installation component 2. The PCB test upper mold mechanism 4 will be described in detail below. The PCB test upper mold mechanism 4 includes a support frame 19 arranged on the main support component 1 on both sides of the PCB transverse movement component 3, an upper template 20 is arranged on the support frame 19, a plurality of SMP RF connector adaptive components 21 are arranged on the upper template 20, and a plurality of elastic rods are arranged on the upper template 20.

[0030] In order to facilitate the static elimination of the PCB board, an static elimination device 5 is provided on the main installation component 2 at one side of one of the PCB test upper mold mechanisms 4. In order to facilitate the pressing test of the circulator chip, a circulator pressing test mechanism 6 is provided on the main installation component 2 at one side of the static elimination device 5.

[0031] In order to facilitate the storage of the circulator chip, an circulator upper and lower material bins 7 are arranged on the main installation component 2 at one side of the circulator pressing test mechanism 6, and the circulator upper and lower material bins 7 include a full bin 25, an empty bin 26, an OK bin 27, and an NG bin 28 arranged on the main installation component 2. A lifting module 29 is arranged at the bottom of the full bin 25, the empty bin 26, the OK bin 27, and the NG bin 28, and a sensor is arranged on one side of the full bin 25.

[0032] In order to facilitate the installation of the feeding vision system 9, an auxiliary support assembly 8 is arranged on the main installation assembly 2 at one side of the upper and lower material bins 7 of the circulator, and the auxiliary support assembly 8 includes an auxiliary support frame 31 arranged on the main installation assembly 2 at one side of the upper and lower material bins 7 of the circulator, and the feeding vision system 9 is arranged on the auxiliary support frame 31.

[0033] In order to facilitate the photographic positioning of the PCB board, a loading vision system 9 is provided on the auxiliary support assembly 8 , and the loading vision system 9 includes a photographic positioning camera 32 provided on the auxiliary support frame 31 .

[0034] In order to facilitate transportation, an auxiliary transportation component 10 is provided on the main support component 1. The auxiliary transportation component 10 will be described in detail below. The auxiliary transportation component 10 includes an auxiliary transportation robot 33 arranged on the main installation component 2 and located on one side of the auxiliary support component 8. A transportation suction cup 34 is provided at the output end of the auxiliary transportation robot 33. In order to facilitate photographing and identifying the product after transportation, an identification camera is provided on the transportation suction cup 34.

[0035] The specific structure of the present invention is described in detail above, and the working principle of the present invention will be described below: multiple RF port tests, the photo positioning camera 32 takes photos and positions the PCB board, then the auxiliary transport robot 33 drives the transport suction cup 34 to grab the PCB board, the recognition camera on the transport suction cup 34 recognizes the character QR code on the PCB board and transmits the system record, the auxiliary transport robot 33 moves the recognized PCB board to the test lower mold carrier 17, the recognition camera takes photos and detects the SMP RF port and the optical fiber port on the PCB board in turn, after the detection is completed, the auxiliary transport robot 33 transports another PCB board to another test lower mold carrier 17, the recognition camera takes photos and detects the SMP RF port and the optical fiber port on the PCB board transported for the second time, after completion, the PCB transverse conveying module 14 drives the test lower mold carrier 17 to move to the bottom of the upper template 20, the lifting assembly 16 drives the test lower mold carrier 17 to lift, and the PCB board first contacts Dozens of elastic rods installed on the upper template 20 gradually press the PCB board as the test lower mold carrier plate 17 rises, and then the SMP RF port is inserted into the SMP RF connector adaptive component 21, and at the same time, the optical port test solder joint of the PCB board contacts the optical fiber test needle mold component 23, and the low-frequency test port test point contacts the low-frequency test needle mold component 24. The test lower mold carrier plate 17 rises to the height set by pre-debugging, and the cylinder of the low-frequency test needle mold component 24 recovers the low-frequency probe and contacts the test points respectively, so that each test point is fully contacted to start the test. After the test is completed, the cylinder of the low-frequency test needle mold component 24 extends to separate the low-frequency probe from the test point, and the test lower template descends. During the descent, the elastic force of the elastic rod is used to separate the SMP RF port from the SMP RF connector and descend to the initial position. The PCB transverse conveying module 14 drives the tested PCB board back to the loading and unloading position, and the auxiliary handling manipulator 33 unloads the tested PCB board to the unloading docking station;

[0036] When testing the circulator, the auxiliary handling robot 33 places the circulator in the circulator test fixture of the circulator pressing test mechanism 6, and takes a photo of the circulator through the recognition camera for detection. After the detection, the circulator pressing test mechanism 6 presses down the circulator to start testing. During the test, after the test is completed, the auxiliary handling robot 33 picks up the tested product and places the tested product in the OK or NG bin 28 according to the test results. The auxiliary handling robot 33 puts the material in the full bin 25 into the circulator test fixture, takes a photo again to detect whether it is placed in place, and then conducts the test. Then, if the entire tray of material in the full bin 25 has been tested, the auxiliary handling robot 33 absorbs the empty tray and places it in the empty tray bin 26. The position sensor of the full bin 25 detects that the upper tray is taken away, and the lifting module 29 under the bin will raise the lower tray to the original material taking height, thereby repeatedly realizing the automatic clamping, automatic loading and unloading, automatic sorting, and automatic pressing test of the circulator.

[0037] The PCB test equipment of the present technical solution has an ingenious structural design, strong practicality, and stable operation. By using the PCB test equipment, automatic testing of various RF ports on the PCB board is realized. At the same time, automatic testing of the circulator is also realized, which effectively improves the test efficiency and the test accuracy.

[0038] The above technical solutions only reflect the preferred technical solutions of the technical solutions of the present invention. Some changes that may be made to certain parts thereof by technicians in this technical field all reflect the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A PCB test device for multiple radio frequency ports, characterized in that: The invention comprises a main support component (1), wherein a main mounting component (2) is arranged on the main support component (1), a PCB transverse movement component (3) is arranged on the main mounting component (2), PCB test upper mold mechanisms (4) are arranged on both sides of the PCB transverse movement component (3) on the main mounting component (2), an electrostatic elimination device (5) is arranged on one side of one of the PCB test upper mold mechanisms (4) on the main mounting component (2), a circulator pressing test mechanism (6) is arranged on the main mounting component (2) on one side of the electrostatic elimination device (5), a circulator upper and lower material bins (7) are arranged on the main mounting component (2) on one side of the circulator pressing test mechanism (6), an auxiliary support component (8) is arranged on the main mounting component (2) on one side of the circulator upper and lower material bins (7), a loading visual system (9) is arranged on the auxiliary support component (8), and an auxiliary transport component (10) is arranged on the main support component (1).

2. A PCB testing device for multiple radio frequency ports according to claim 1, characterized in that: The main support assembly (1) comprises a main support frame (11), a main mounting assembly (2) is arranged on the main support frame (11), and a plurality of balance adjustment feet (12) are arranged at the bottom of the main support frame (11).

3. A PCB testing device for multiple radio frequency ports according to claim 1, characterized in that: The main mounting assembly (2) comprises a main mounting plate (13) arranged on the main supporting assembly (1), and a PCB lateral movement assembly (3) is arranged on the main mounting plate (13).

4. A PCB testing device for multiple radio frequency ports according to claim 1, characterized in that: The PCB transverse movement component (3) comprises a PCB transverse movement conveying module (14) arranged on the main installation component (2); a moving plate (15) is arranged at a moving part of the PCB transverse movement conveying module (14); a lifting component (16) is arranged on the moving plate (15); a test lower mold carrier plate (17) is arranged on the lifting component (16); and a plurality of support columns are arranged on the test lower mold carrier plate (17).

5. A PCB testing device for multiple radio frequency ports according to claim 1, characterized in that: The PCB test upper mold mechanism (4) comprises a support frame (19) arranged on the main support component (1) and located on both sides of the PCB transverse movement component (3); an upper mold plate (20) is arranged on the support frame (19); a plurality of SMP radio frequency connector adaptive components (21) are arranged on the upper mold plate (20); and a plurality of elastic rods are arranged on the upper mold plate (20).

6. A PCB testing device for multiple radio frequency ports according to claim 5, characterized in that: An optical fiber test needle mold assembly (23) is arranged on the upper template (20) at one side of the SMP radio frequency connector adaptive assembly (21), and a low-frequency test needle mold assembly (24) is arranged on the upper template (20) at one side of the optical fiber test needle mold assembly (23).

7. A PCB testing device for multiple radio frequency ports according to claim 1, characterized in that: The upper and lower bins (7) of the annular device include a full bin (25), an empty bin (26), an OK bin (27), and an NG bin (28) arranged on the main mounting assembly (2); a lifting module (29) is arranged at the bottom of the full bin (25), the empty bin (26), the OK bin (27), and the NG bin (28); and a sensor is arranged on one side of the full bin (25).

8. A PCB testing device for multiple radio frequency ports according to claim 1, characterized in that: The auxiliary support assembly (8) comprises an auxiliary support frame (31) arranged on the main mounting assembly (2) and located on one side of the upper and lower material bins (7) of the annular device, and a loading vision system (9) is arranged on the auxiliary support frame (31), and the loading vision system (9) comprises a photo positioning camera (32) arranged on the auxiliary support frame (31).

9. A PCB testing device for multiple radio frequency ports according to claim 1, characterized in that: The auxiliary transport component (10) comprises an auxiliary transport robot (33) arranged on the main installation component (2) and located on one side of the auxiliary support component (8); a transport suction cup (34) is arranged at the output end of the auxiliary transport robot (33); and a recognition camera is arranged on the transport suction cup (34).

10. A working method of a PCB testing device for multiple radio frequency ports according to any one of claims 1 to 9, characterized in that: The following steps are involved: A plurality of radio frequency port tests are performed, the camera for taking photos and positioning the PCB board is used for taking photos and positioning, then the auxiliary transport manipulator (33) drives the transport suction cup (34) to grab the PCB board, the recognition camera on the transport suction cup (34) recognizes the character two-dimensional code on the PCB board and transmits the system record, the auxiliary transport manipulator (33) moves the recognized PCB board to the test lower mold carrier (17), the recognition camera sequentially takes photos and detects the SMP radio frequency port and the optical fiber port on the PCB board, after the detection is completed, the auxiliary transport manipulator (33) moves another PCB board to another test lower mold carrier (17), the recognition camera sequentially takes photos and detects the SMP radio frequency port and the optical fiber port on the PCB board transported for the second time, after the completion, the PCB transverse conveying module (14) drives the test lower mold carrier (17) to move to the bottom of the upper mold plate (20), the lifting assembly (16) drives the test lower mold carrier (17) to lift, and the PCB board first contacts the upper mold plate installed on the upper mold plate (20) Dozens of elastic rods gradually press the PCB board as the test lower mold carrier (17) rises, and then the SMP RF port is inserted into the SMP RF connector adaptive component (21). At the same time, the optical port test solder joint of the PCB board contacts the optical fiber test needle mold component (23), and the low-frequency test port test point contacts the low-frequency test needle mold component (24). The test lower mold carrier (17) rises to a height set by pre-debugging. The cylinder of the low-frequency test needle mold component (24) retracts the low-frequency probe and contacts the test points respectively, so that each test point is fully contacted to start the test. After the test is completed, the cylinder of the low-frequency test needle mold component (24) extends to separate the low-frequency probe from the test point, and the test lower template descends. During the descending process, the elastic force of the elastic rod is used to separate the SMP RF port from the SMP RF connector and descend to the initial position. The PCB transverse conveying module (14) drives the tested PCB board back to the loading and unloading position, and the auxiliary handling manipulator (33) unloads the tested PCB board to the unloading docking station; When testing the circulator, the auxiliary handling robot (33) places the circulator in the circulator test fixture of the circulator pressing test mechanism (6), and takes a photo of the circulator through the recognition camera. After the detection, the circulator pressing test mechanism (6) presses down the circulator to start the test. During the test, after the test is completed, the auxiliary handling robot (33) picks up the tested product and places the tested product in the OK or NG bin (28) according to the test result. The auxiliary handling robot (33) puts the material in the full bin (25) into the circulator test fixture, takes a photo again to detect whether it is placed in place, and then conducts the test. Then, if the entire tray of material in the full bin (25) has been tested, the auxiliary handling robot (33) absorbs the empty tray and places it in the empty tray bin (26). The position sensor of the full bin (25) detects that the tray on the upper layer has been taken away, and the lifting module (29) below the bin will raise the tray on the lower layer to the original material taking height, thereby repeatedly realizing the automatic clamping, automatic loading and unloading, automatic sorting, and automatic pressing test of the circulator.

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