AC power supply to reduce corrosion

Abstract

To provide an AC power supply method and a power transmission circuit to reduce corrosion.SOLUTION: In a system that compensates electric fields that can cause corrosion at contact points, a voltage waveform at the contact points has 0 volt average and therefore 0 net electric field. The galvanic voltage generated by the dissimilar metals used at the contact points and a housing can create an electric field, and the current induced by the galvanic field can be blocked by capacitively coupling the contact points to their corresponding circuits.SELECTED DRAWING: None

Description

Technical Field

[0001] Cross-Reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 541,726 entitled "AC Power Supply for Corrosion Reduction" filed on September 29, 2023, and U.S. Non-Provisional Patent Application No. 18 / 896,299 entitled "AC Power Supply for Corrosion Reduction" filed on September 25, 2024, which are hereby incorporated by reference in their entirety into this specification for all purposes.

Background Art

[0002] The amount of data transmitted between electronic devices has increased significantly in recent years. Currently, large amounts of audio, streaming video, text, and other types of data content are regularly transmitted between desktop and portable computers, media devices, handheld media devices, displays, storage devices, and other types of electronic devices.

[0003] Power and data can be provided from one electronic device to another via a cable that may include one or more wire conductors, fiber optic cables, or other conductors. Connector inserts can be placed at each end of these cables and inserted into a connector receptacle of a communication device or power transmission electronic device. Contacts in or on the connector insert can form an electrical connection with corresponding contacts in the connector receptacle. Other devices can have contacts on the surface of the device. Paths for power and data can be formed when devices are mounted or placed adjacent to each other and corresponding contacts are electrically connected to each other.

[0004] These various contacts within connector inserts, connector receptacles, or on the surface of a device may be exposed to the local environment. These contacts may come into contact with liquids, moisture, or other harmful contaminants. For example, liquid may spill onto these contacts, or the device may be placed so that its contacts land in a pool of liquid. Users may swim or exercise while wearing or holding an electrical device. These activities may place the contacts of the electronic device in positions where they may come into contact with various contaminants.

[0005] These liquids or other contaminants can corrode and damage the contacts. This corrosion can be significantly exacerbated by the presence of an electric field, such as when a constant voltage or DC voltage is applied to the contacts. As a result, power contacts can be particularly susceptible to corrosion.

[0006] Therefore, there is a need for methods, structures, and apparatus that can supply power through device contacts while minimizing corrosion of the device contacts. [Overview of the project]

[0007] Accordingly, embodiments of the present invention can provide a method, structure, and apparatus that can supply power through a pair of power contacts while minimizing corrosion. Exemplary embodiments of the present invention can provide a method, structure, and apparatus that can supply power through a pair of power contacts while minimizing corrosion by supplying power using a differential AC voltage having an average voltage of 0 volts (or close to 0 volts). These and other embodiments of the present invention can prevent current flow that may arise from galvanic voltages by capacitively coupling the power contacts to circuits in an electronic device.

[0008] Contacts on electronic devices can be exposed to corrosive materials and fluids. These corrosive materials and fluids can induce corrosion of the contacts, thereby releasing ions from them. In the presence of a DC electric field, corrosion and release of ions can be accelerated. Applying an AC electric field can reduce net corrosion of the contacts. By applying an AC electric field with a voltage of 0 volts or a near-average value, the movement of ions from the contacts can be made at least approximately equal to the movement of ions to the contacts. This symmetrical movement can reduce corrosion of the contacts. This effect can be reduced by a galvanic voltage that may exist between a first metal forming the contacts and a second metal forming the housing or enclosure of the electronic device. This galvanic voltage can generate an electric field that may also cause corrosion. The galvanic voltage can provide a current flow through the contacts and through the circuitry in the electronic device to the housing or enclosure, which can be grounded. The electron flow of this current can equilibrate the movement of ions in the liquid. This current can be interrupted by capacitive coupling of the power contacts to the circuitry in the electronic device. In other words, the capacitor can act as a DC block, blocking the DC component of the current induced by the galvanic voltage, and further reducing corrosion of the power contacts.

[0009] Various contact structures can be used in these and other embodiments of the present invention. A first contact on a first device can be mated with a second contact on a second device. The first contact can be spring-biased to provide a contact force, and the second contact can be fixed to a device enclosure and acted upon by the contact force of the first contact. The first contact can be biased by a pair of inclined coil springs. The inclined coil springs can be positioned within the housing such that their central axes are perpendicular to the connection direction of the first contacts. When the first and second devices are mated, the first contact can be pushed inward into the first device. The first contact can push the plate and holder into the inclined coil spring, thereby crushing or flattening the diameter of the inclined coil spring. The deformed inclined coil spring can provide a bending force to the second contact. When the first and second devices are separated, the inclined coil spring returns to its original shape, allowing the first contact to be pushed away from the first device. The movement of the first contact can be restricted by mounting the first contact and pin to a holder, and the pin can move within a corresponding slot in the housing of the first device. The inclined coil spring can be held in place using one or more pins positioned through the central axis of the inclined coil spring.

[0010] In these and other embodiments of the present invention, the first contact can be biased by a single inclined coil spring. The inclined coil spring can be positioned in a housing such that its central axis is perpendicular to the connection direction of the first contact. When the first and second devices are mated, the first contact can be pushed inward into the first device. The first contact can push the plate and holder into the inclined coil spring, thereby crushing or flattening the diameter of the inclined coil spring. The deformed inclined coil spring can provide a bending force to the second contact. When the first and second devices are separated, the inclined coil spring returns to its original shape, pushing the first contact away from the first device. The movement of the first contact can be restricted by mounting a pin in the holder, the pin can move within a slot in the housing of the first device. The inclined coil spring can be held in place using a number of slats mounted on a frame.

[0011] In these and other embodiments of the present invention, the first contact can be biased by one or more stacks of Belleville washers. The Belleville washers can be arranged back-to-back and then stacked. The stacks can be positioned on alignment pins to restrict the movement of the Belleville washers. When the first and second devices are mated, the first contact can be pushed inward into the first device. The first contact can push the plate into the Belleville washers. When the plate is pushed into the stack of Belleville washers, the Belleville washers can be compressed, thereby reducing the length of the stack of Belleville washers. The Belleville washers can have the same or different thicknesses so that they provide at least some degree of constant force across the deflection of the first contact. When the first and second devices are separated, the Belleville washers can return to their original shape, pushing the first contact away from the first device. The first contact and plate can be mounted in a holder. The movement of the first contact can be restricted by mounting the pin in a holder, and the pin can move within a slot in the housing of the first device.

[0012] In these and other embodiments of the present invention, the second contact can be fixed within the second device, and the first contact can provide force to the second contact. The second contact may be supported by a housing which is sealed to the housing or enclosure of the second device by a sealing ring. The contact and housing may be attached to the flex using pressure-sensitive adhesive or other adhesive. The flex may be held in place by a cowling. The cowling may be attached to the flex using pressure-sensitive adhesive or other adhesive. The cowling may be fixed to the housing or enclosure of the second device.

[0013] In these and other embodiments of the present invention, various circuits can be used to transmit power. These circuits can be used to transmit power from a first device to a second device, from a second device to a first device, or the power can be transmitted bidirectionally or round trip between the first and second devices. For example, the first device can receive power from a charger or power adapter. While the first device is being powered, the second device can be connected to the first device. This can enable the first device to supply power to the second device. During device operation, the second device can return power to the first device. During device operation, the first device can continue to supply power to the second device as needed.

[0014] These power circuits may be the same or substantially similar in the first and second devices. In these and other embodiments of the present invention, the first and second devices may differ, for example, in the case of unidirectional or one-way power transmission between the first and second devices.

[0015] These and other embodiments of the present invention can provide a power transmission circuit having a battery. A first power transmission circuit can be housed in a first device, and a second power transmission circuit can be housed in a second device. The battery can be connected to the power circuit in the first device. The battery can be connected to a switch that can be opened when the first device is disconnected from the second device and closed when power is being transmitted. The switch can then be connected to a boost / buck circuit, and the boost / buck circuit can be connected to an inverter / rectifier circuit. The inverter / rectifier circuit can provide a capacitively coupled output signal to a pair of first contacts. The capacitively coupled output signal can be received from the pair of first contacts by a pair of second contacts of the second device. The rectifier / inverter circuit, which is obtained by connecting with the inverter / rectifier circuit of the first device, can receive the output signal and provide an output to a buck / boost circuit which may be identical or similar to the boost / buck circuit in the first electronic device. The buck / boost circuit can be coupled to the battery and internal circuitry of a second device via a switch.

[0016] Power can be transmitted from a first device to a second device. In the first power transmission circuit, a switch can connect the battery to a boost / buck circuit. The boost / buck circuit can act as a boost to increase the voltage from the battery and provide high and low voltages to the inverter / rectifier circuit. The inverter / rectifier circuit can operate as an inverter and provide a differential output signal. The differential output signal can be capacitively coupled to a pair of first contacts of the first device.

[0017] The differential output signal can be received by a pair of second contacts of the second device. The differential output signal can be capacitively coupled to a rectifier / inverter circuit, which can convert the differential output signal into high and low voltages. The high and low voltages can be stepped down by a buck / boost circuit, which can supply power through a switch to charge the battery of the second device. Although power is described as being transmitted from the first device to the second device, power can also be transmitted from the second device to the first device.

[0018] An inverter circuit according to an embodiment of the present invention can provide a variety of output differential signals. For example, an out-of-phase (or 180° phase-shifted) sine wave can be supplied to a first pair of contacts or a second pair of contacts. An out-of-phase square wave can be supplied to a first pair of contacts or a second pair of contacts. A filtered and out-of-phase square wave can be supplied to a first pair of contacts or a second pair of contacts to remove high-frequency components. A bandwidth-limited and out-of-phase square wave can be supplied to a first pair of contacts or a second pair of contacts. Other differential waveforms can be supplied to a first pair of contacts or a second pair of contacts.

[0019] The frequency of the differential output signal can be varied. The amplitude of the differential output signal can be varied. These parameters can be changed as various conditions for the first pair of contacts or the second pair of contacts change. For example, if liquid is detected on one or more contacts, the frequency, amplitude, or both can be changed for the differential output signal. The differential output signal can be interrupted under certain conditions.

[0020] A first contact in the first device can be capacitively coupled to a first power transmission circuit in the first device, and a second contact in the second device can be capacitively coupled to a second power transmission circuit in the second device. The presence of a capacitor used for this AC coupling or capacitive coupling may interrupt the DC current path between the first contact, the second contact, the enclosure for the first device, and the enclosure for the second device.

[0021] For example, a liquid or fluid may be present on some or all of the first contact, the second contact, the enclosure for the first device, and the enclosure for the second device. As part of an electrochemical corrosion process, the fluid can induce corrosion of one or more of the first contact, the second contact, the enclosure for the first device, or the enclosure for the second device, thus releasing ions from the structure into the fluid. The movement of ions into the fluid may be part of a loop involving a galvanic voltage that induces electron transfer from the contact through the circuit of either the first or second device, and then to the grounded housing or enclosure. An input coupling capacitor can block the DC component of this current, thereby blocking the loop and slowing the outflow of ions from the contact into the fluid.

[0022] In short, the presence of an electric field can move ions from the contacts to the liquid. This process can corrode the contacts. Therefore, the electric field can be compensated for by embodiments of the present invention. For example, the voltage waveform at the contacts can have a 0-volt average and therefore a 0-net electric field. Also, a galvanic voltage generated by dissimilar metals used by the contacts and housing can generate an electric field, but the current induced by the galvanic electric field can be blocked by capacitively coupling the contacts to their corresponding circuits.

[0023] Data can be transferred between the first and second devices in various ways. The amplitude of the differential output signal can be modulated with data. The phase of the differential output signal can be modulated with data. The frequency of the differential output signal can be modulated with data. These modulations are applied by a power and data transmitting device and can be recovered by a power and data receiving device. In these and other embodiments of the present invention, the power transmitting device can provide a differential output signal. The power receiving device can be a data transmitting device and can modulate the load as seen from the power transmitting device. The load can be modulated by data that the power receiving device transmits back to the power transmitting device. The power transmitting device may also be a data receiving device and can recover the data.

[0024] These and other embodiments of the present invention may include additional features that can help prevent or reduce corrosion. For example, they may include electrical impedance spectrometers. These circuits can provide a voltage waveform to one or more contacts of the device. The resulting voltage, the resulting current, or both can be measured. The resulting current may indicate that current is flowing through the liquid. The phase shift between the applied voltage waveform and the resulting current or resulting voltage may indicate the quantity of the type of liquid. To prevent corrosion pathways, a coupling capacitor may be inserted between the contacts and the electrical impedance spectrometer.

[0025] Embodiments of the present invention may provide power transmission circuits and devices that can be placed in various types of devices such as portable computing devices, tablet computers, desktop computers, laptops, all-in-one computers, wearable computing devices, mobile phones, smartphones, media phones, storage devices, portable media players, navigation systems, monitors, power supplies, video distribution systems, adapters, remote control devices, chargers, and other devices.

[0026] The first device and the second device may be various types of devices. The first device and the second device may be connected via a cable, but they are often directly mated together. For example, the first device may be an audio device such as headphones or earphones, and the second device may be a case for carrying and charging the audio device; or the second device may be an audio device such as headphones or earphones, and the first device may be a case for carrying and charging the audio device. The first device may be a tablet computer, and the second device may be a case and a keyboard; or the second device may be a tablet computer, and the first device may be a case and a keyboard. The first device may be a watch and the second device may be a watch band, or the second device may be a watch and the first device may be a watch band. The first device and the second device may also be other types of devices that can be connected to each other by direct mating.

[0027] Various embodiments of the present invention may incorporate one or more of these and other features described herein. A better understanding of the nature and advantages of the present invention may be obtained by reference to the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] [Figure 1] FIG. 1 is a diagram showing an electronic system according to an embodiment of the present invention.

[0029] [Figure 2] FIG. 2 shows a spring-biased contact assembly according to an embodiment of the present invention.

[0030] [Figure 3] FIG. 3 shows a spring-biased contact assembly according to an embodiment of the present invention.

[0031] [Figure 4] Figure 3 is an exploded view of the contact assembly.

[0032] [Figure 5] The force-deflection curve of the first junction according to one embodiment of the present invention is shown.

[0033] [Figure 6] A modified example of a spring biasing contact assembly according to one embodiment of the present invention is shown.

[0034] [Figure 7] Figure 6 is an exploded view of the contact assembly.

[0035] [Figure 8] This is a cross-sectional view of a second contact assembly according to one embodiment of the present invention.

[0036] [Figure 9] Figure 8 is an exploded view of the contact assembly.

[0037] [Figure 10] Figure 1 is a block diagram of a charging system for an electronic system according to one embodiment of the present invention.

[0038] [Figure 11] Figure 1 is a schematic diagram of a contact interface for an electronic system according to one embodiment of the present invention.

[0039] [Figure 12] This is a simplified circuit diagram of a portion of a power system circuit according to one embodiment of the present invention.

[0040] [Figure 13] This is a simplified circuit diagram of a partial replacement of a power system circuit according to one embodiment of the present invention.

[0041] [Figure 14]This is a simplified circuit diagram of two power system circuit components that transmit power, according to one embodiment of the present invention.

[0042] [Figure 15] This shows a contact assembly according to one embodiment of the present invention. [Figure 16] This shows a contact assembly according to one embodiment of the present invention. [Figure 17] This shows a contact assembly according to one embodiment of the present invention.

[0043] [Figure 18A] The profile of a contact assembly according to one embodiment of the present invention is shown. [Figure 18B] The profile of a contact assembly according to one embodiment of the present invention is shown. [Figure 18C] The profile of a contact assembly according to one embodiment of the present invention is shown. [Figure 18D] The profile of a contact assembly according to one embodiment of the present invention is shown.

[0044] [Figure 19] This document shows a contact assembly for a contact interface according to one embodiment of the present invention.

[0045] [Figure 20] Further details of a contact assembly according to one embodiment of the present invention are shown.

[0046] [Figure 21] This document shows a contact assembly for a contact interface according to one embodiment of the present invention.

[0047] [Figure 22] A cross-sectional side view of a contact assembly according to one embodiment of the present invention is shown.

[0048] [Figure 23] This shows the galvanic corrosion pathway in an electronic device according to an embodiment of the present invention.

[0049] [Figure 24] This demonstrates arbitrary DC charging in an electronic device according to one embodiment of the present invention.

[0050] [Figure 25] This shows the AC waveform for power transmission using one embodiment of the present invention.

[0051] [Figure 26] This shows a charging path through an electronic system according to one embodiment of the present invention.

[0052] [Figure 27] This shows a charging path through an electronic system according to one embodiment of the present invention.

[0053] [Figure 28] This shows a charging path through an electronic system according to one embodiment of the present invention.

[0054] [Figure 29] The data shown can be used by a method for determining the type of material used in a contact, according to one embodiment of the present invention.

[0055] [Figure 30] This document describes a method for optimizing the charging waveform according to one embodiment of the present invention. [Modes for carrying out the invention]

[0056] Figure 1 shows an electronic system according to one embodiment of the present invention. This figure, like the other figures included, is provided for illustrative purposes only and does not limit any possible embodiments of the present invention or the claims.

[0057] In this example, the electronic system 10 may include a first device 100 that can be connected to a second device 200 to share data, power, or both. The first contacts 110, 112, and 114 (collectively referred to as the first contacts 110) on the first device 100 may be electrically connected to the second contacts 210, 212, and 214 (collectively referred to as the second contacts 210) on the second device 200. The first contacts 110 on the first device 100 may be electrically connected to the second contacts 210 on the second device 200 using a cable (not shown). In other embodiments of the present invention, the first contacts 110 of the first device 100 may be directly and electrically connected to the second contacts 210 of the second device 200. In various embodiments of the present invention, the first contacts 110 and the second contacts 210 may be power contacts or other types of contacts. An example of an embodiment of the present invention in which the first contact 110, the first contact 112, the second contact 210, and the second contact 212 are power contacts is shown in the following figure. The first contact 114 and the second contact 214 can be ground contacts, data or signal contacts, or other types of contacts.

[0058] Embodiments of the present invention enable power transmission from a first device 100 to a second device 200 by providing an AC differential voltage having an average value of 0 volts or near 0 volts at the first contacts 110 and 112. Power can also be transmitted from the second device 200 to the first device 100 by providing an AC differential voltage having an average value of 0 volts or near 0 volts at the second contacts 210 and 212. This can provide reduced or low levels of ion transfer to the contacts, thereby reducing corrosion of the first contacts 110 and 210 when the device power contacts are exposed to contaminants. The first contact 110 can be capacitively coupled to a power transmission circuit 120, and the second contact 210 can be capacitively coupled to a power transmission circuit 220. Capacitive coupling can eliminate or reduce currents generated by galvanic voltages between the first contact 110, the second contact 210, and dissimilar metals used in the enclosure or housing of the first device 100 and the second device 200.

[0059] The first contact 110 may be coupled to a power transmission circuit 120 in the first device 100. The power transmission circuit 120 can supply power to or draw power from the battery 190. The second contact 210 may be coupled to a power transmission circuit 220 in the second device 200. The power transmission circuit 220 can supply power to or draw power from the battery 290.

[0060] The first device 100 and the second device 200 can be various types of devices. The first device 100 and the second device 200 can be connected via a cable, but they are often directly mated to each other. For example, the first device 100 may be an audio device such as headphones or earphones, and the second device 200 may be a case for carrying and charging the audio device, or the second device 200 may be an audio device such as headphones or earphones, and the first device 100 may be a case for carrying and charging the audio device. The first device 100 may be a tablet computer, and the second device 200 may be a case and keyboard, or the second device 200 may be a tablet computer, and the first device 100 may be a case and keyboard. The first device 100 may be a watch, and the second device 200 may be a watch band, or the second device 200 may be a watch, and the first device 100 may be a watch band. The first device 100 and the second device 200 may be other types of devices that can be connected to each other by direct mating.

[0061] The first contact 110 can be a spring-biased contact that can mate with a fixed second contact 210. The first contact 110 can be spring-biased to provide force to the second contact 210 in order to provide a good electrical connection. An example of the first contact is shown in the following figure.

[0062] Figure 2 shows a spring-biased contact assembly according to one embodiment of the present invention. The first contact assembly 20 may include a first contact 110. The first contact 110 can be biased by a pair of inclined coil springs 130. The inclined coil springs 130 may be positioned within the housing 150 such that the central axis of the inclined coil springs 130 is perpendicular to the connection direction of the first contact 110. When the first device 100 and the second device 200 (both shown in Figure 1) are mated, the first contact 110 may be pushed inward into the first device 100. The first contact 110 pushes the plate 170 and holder 160 into the inclined coil springs 130, thereby crushing or flattening the inclined coil springs 130 in the direction of their diameters. When the first device 100 and the second device 200 are disconnected, the inclined coil spring 130 returns to its original shape, allowing the first contact 110, plate 170, and holder 160 to be pushed away from the first device 100. The movement of the first contact 110 can be restricted by attaching the first contact and pin 162 to the holder 160, and the pin 162 can move within a slot 152 in the housing 150 of the first device 100. The inclined coil spring 130 can be held in place using one or more pins 140 positioned along the central axis of the inclined coil spring 130. The wire 180 can be coupled to a coupling capacitor, such as the coupling capacitor C1 in Figure 11.

[0063] Figure 3 shows a spring-biased contact assembly according to one embodiment of the present invention. In these and other embodiments of the present invention, the first contact 110 can be biased by a single inclined coil spring 230. The first contact assembly 30 may include the inclined coil spring 230. The inclined coil spring 230 may be positioned within the housing 250 such that its central axis is perpendicular to the connection direction of the first contact 110. When the first device 100 and the second device 200 (both shown in Figure 1) are mated, the first contact 110 can be pushed inward into the first device 100. The first contact 110 can push the plate 270 and holder 260 into the inclined coil spring 230, thereby crushing or flattening the inclined coil spring 230 in its diametrical direction. When the first device 100 and the second device 200 are disconnected, the inclined coil spring 230 returns to its original shape, allowing the first contact 110, plate 270, and holder 260 to be pushed away from the first device 100. The movement of the first contact 110 can be restricted by attaching the first contact 110 and pin 262 to the holder 260, and the pin 262 can move within a slot 252 in the housing 250 within the first device 100. The inclined coil spring 130 can be held in place using a number of slats 242 attached to the frame 240. The wire 280 can couple the first contact 110 to a coupling capacitor such as the coupling capacitor C1 in Figure 11.

[0064] Figure 4 is an exploded view of the contact assembly of Figure 3. The first contact assembly 30 may include a slanted coil spring 230. The slanted coil spring 230 can be held in place by a slat 242 extending from the frame 240. A plate 270 can further enclose the slanted coil spring 230. The plate 270 can be mounted on the bottom of the holder 260. The holder 620 can hold the first contact 110 in the slot 264. The plate 270 can be mounted on the underside of the holder 260. A wire 280 can transmit voltage and current from the first contact 110 to the power transmission circuit 120 in the first device 100. The holder 260 can slide through a range defined by a pin 262 in a slot 252 within the housing 250 (shown in Figure 3). When the first device 100 and the second device 200 (both shown in Figure 1) are mated together, the first contact 110 can be pushed inward into the first device 100. The first contact 110 can push the plate 170 and holder 160 into the inclined coil spring 130, thereby crushing or flattening the inclined coil spring 130 in its diametrical direction. When the first device 100 and the second device 200 are separated, the inclined coil spring 130 returns to its original shape, pushing the plate 270, holder 260, and the first contact 110 away from the first device 100.

[0065] Figure 5 shows a force-deflection curve of a first contact according to one embodiment of the present invention. Graph 500 shows a force-deflection curve 530 plotted as a function of the contact force 510 provided by the first contact 110 (shown in Figure 1) and the deflection 520 of the first contact. When the first and second devices are mated, the first contact 110 can deflect by an amount that may be within the range 540. The deflection may vary within the range due to manufacturing tolerances in the formation of the first device 100, the second device 200, the first contact 110, the second contact 210, and the manner in which they are mated. Therefore, it may be desirable that the contact force be independent as a function of displacement. That is, it may be desirable that the force-deflection curve 530 be at least relatively flat in the range 540. This can be achieved using the inclined coil springs 130 and 230 in the example of Figures 2 and 3. The force-deflection curve 530 can have a flat section within range 540 using other structures. An example is shown in the figure below.

[0066] Figure 6 shows a modified example of a spring-biased contact assembly according to one embodiment of the present invention. In the contact assembly 30, the first contact 110 can be biased by one or more stacks of Belleville washers 630. The Belleville washers 630 can be arranged back-to-back and then stacked. The stack of Belleville washers 630 can be positioned on alignment pins 644 to restrict the movement of the Belleville washers 630. When the first device 100 and the second device 200 (both shown in Figure 1) are mated, the first contact 110 can be pushed inward into the first device 100. The first contact 110 can push the plate 670 into the Belleville washers 630. When the plate 270 is pushed into the stack of Belleville washers 630, the Belleville washers 630 begin to compress, thereby reducing the length of the stack of Belleville washers 630. The Belleville washer 630 may have the same or different thicknesses so that it can provide at least some degree of constant force across the deflection of the first contact 110. When the first device 100 and the second device 200 are separated, the Belleville washer 630 returns to its original shape, allowing the first contact 110, holder 660, and plate 670 to be pushed away from the first device 100. The wire 680 can transmit voltage and current from the first contact 110 to the power transmission circuit 120 in the first device 100 (all shown in Figure 1). An insulator 682 may be provided around the wire 680.

[0067] Figure 7 is an exploded view of the contact assembly of Figure 6. A stack of Belleville washers 630 can be positioned on the alignment pin 644 in the contact assembly 30. The Belleville washers 630 can be held between the frame 640 and the plate 670. The slat 642 can extend from the frame 640. Wires 680 can transmit voltage and current from the first contact 110 to the power transmission circuit 120 in the first device 100 (all shown in Figure 1). A holder 660 can support the pin 662 (shown in Figure 6), the first contact 110, and the plate 670. The holder 660 can move over the entire range defined by the pin 662 in an opening (not shown) in the housing 650.

[0068] Figure 8 is a cross-sectional view of a second contact assembly according to one embodiment of the present invention. In these and other embodiments of the present invention, the second contact 210 in the second contact assembly 80 can be fixed in the second device 200 (shown in Figure 1), and the first contact 110 can provide force to the second contact 210. The second contact 210 can be supported by a housing 810 sealed to the housing or enclosure 890 of the second device 200 by a sealing ring 820. The second contact 210 can be attached to a flexible circuit board 830 using a pressure-sensitive adhesive 840 or other adhesive. The flexible circuit board 830 can be held in place by a cowling 850. The cowling 850 can be attached to the flexible circuit board 830 using a pressure-sensitive adhesive 860 or other adhesive. The cowling 850 can be fixed to the housing or enclosure 890 of the second device 200 by fasteners 892.

[0069] Figure 9 is an exploded view of the contact assembly of Figure 8. The second contact 210 of the second contact assembly 80 can be supported by a housing 810. The housing 810 can be sealed to the housing or enclosure 890 (shown in Figure 8) of the second device 200 (shown in Figure 2) by a sealing ring 820. The second contact 210 can contact a pad 832 on a flexible circuit board 830. The flexible circuit board 830 may include a pad 834 that can be connected to the pad 832 for electrical connection to a power transmission circuit 220 (shown in Figure 1) in the second device 200. The housing 810 can be attached to the flexible circuit board 830 using pressure-sensitive adhesive 840 or other adhesive. The flexible circuit board 830 can be held in place by a cowling 850. The cowling 850 can be attached to the flexible circuit board 830 using pressure-sensitive adhesive 860 or other adhesive. The cowling 850 can be secured to the housing or enclosure 890 of the second device 200 by passing the fasteners 892 through the opening 852 and inserting the fasteners 892 into the corresponding holes in the housing or enclosure 890 of the second device 200.

[0070] In these and other embodiments of the present invention, various circuits can be used to transmit power. These circuits can be used to transmit power from a first device to a second device, from a second device to a first device, or the power can be transmitted bidirectionally or round trip between the first and second devices. For example, the first device can receive power from a charger or power adapter. While the first device is being powered, the second device can be connected to the first device. This can enable the first device to supply power to the second device. During device operation, the second device can return power to the first device. During device operation, the first device can continue to supply power to the second device as needed.

[0071] These power circuits may be the same or substantially similar in the first and second devices. In these and other embodiments of the present invention, the first and second devices may differ, for example, if the power transmission between the first and second devices is unidirectional or one-way. An example is shown in the following figure.

[0072] Figure 10 is a block diagram of a charging system for the electronic system of Figure 1 according to one embodiment of the present invention. A first power transmission circuit 120 can be housed in a first device 100 (shown in Figure 1), and a second power transmission circuit 220 can be housed in a second device 200 (shown in Figure 1). The first power transmission circuit 120 can share power with the second power transmission circuit 220. For example, the power transmission circuit 120 can transmit power to the second power transmission circuit 220. A battery 190 can be connected to a switch 1010, which can be opened when the first device is disconnected from the second device 200 and closed when power is being transmitted. The switch 1010 can then be connected to a boost / buck circuit 1020, which can be connected to an inverter / rectifier circuit 1030. The inverter / rectifier circuit 1030 can provide a capacitively coupled output signal to a pair of first contacts, including first contacts 110 and 112, via capacitors C1 and C2. The capacitively coupled output signal can be received from the pair of first contacts 110 by a pair of second contacts 210, including second contacts 210 and 212 of a second device. The signals on the second contacts 210 and 212 can be capacitively coupled to the rectifier / inverter circuit 1040 via capacitors C3 and C4. The rectifier / inverter circuit 1040 can be identical or similar to the inverter / rectifier circuit 1030 of the first power transmission circuit 120, and can provide an output to a buck / boost circuit 1050, which can be identical or similar to the boost / buck circuit 1020 in the first power transmission circuit 120. The buck / boost circuit 1050 can be coupled to the internal circuits of the battery 290 and the second device 200 via the switch 1060.

[0073] Power can be transmitted from the first device 100 to the second device 200. In the first power transmission circuit 120, the switch 1010 can connect the battery 190 to the boost / buck circuit 1020. The boost / buck circuit 1020 can act as a boost to increase the voltage from the battery 190 and provide high and low voltages to the inverter / rectifier circuit 1030. The inverter / rectifier circuit 1030 can operate as an inverter and provide a differential output signal. The differential output signal can be capacitively coupled to the first contact 110 via capacitor C1 and to the first contact 112 via capacitor C2.

[0074] The differential output signal can be received by the second contacts 210 and 212 of the second device 200. The differential output signal can be capacitively coupled to the rectifier / inverter circuit 1040 via capacitors C3 and C4, which can convert the differential output signal to high and low voltages. The high and low voltages can be stepped down by the buck / boost circuit 1050, which can supply power through the switch 1060 to charge the battery 290 of the second device 200. Although the power is described as being transmitted from the first device 100 to the second device 200, the power can also be transmitted from the second device 200 to the first device 100.

[0075] Various output differential signals can be provided by the inverters of the inverter / rectifier circuits 1030 and rectifier / inverter circuits 1040 according to embodiments of the present invention. For example, out-of-phase (or 180° out of phase with respect to each other) sine waves can be supplied to the first pair of contacts or the second pair of contacts. Out-of-phase square waves can be supplied to the first pair of contacts or the second pair of contacts. A filtered, out-of-phase square wave can be supplied to the first pair of contacts or the second pair of contacts to remove high-frequency components. A bandwidth-limited, out-of-phase square wave can be supplied to the first pair of contacts or the second pair of contacts. Other differential waveforms can be supplied to the first pair of contacts or the second pair of contacts.

[0076] The frequency of the differential output signal can be varied. The amplitude of the differential output signal can be varied. These parameters can be changed as various conditions for the first pair of contacts or the second pair of contacts change. For example, if liquid is detected on one or more contacts, the frequency, amplitude, or both can be changed for the differential output signal. The differential output signal can be interrupted under certain conditions.

[0077] Data can be transferred between the first device 100 and the second device 200 in various ways. The amplitude of the differential output signal can be modulated with data. The phase of the differential output signal can be modulated with data. The frequency of the differential output signal can be modulated with data. These modulations are applied by a power and data transmitting device and can be recovered by a power and data receiving device. In these and other embodiments of the present invention, the power transmitting device can provide a differential output signal. The power receiving device can be a data transmitting device and can modulate the load as seen from the power transmitting device. The load can be modulated by data that the power receiving device transmits back to the power transmitting device. The power transmitting device may also be a data receiving device and can recover the data. Instead of using a differential output signal, data can be transmitted using the first contact 114 of the first device 100 and the second contact 214 of the second device 200 (all shown in Figure 1).

[0078] The first contacts 110 and 112 in the first device 100 can be capacitively coupled to the first power transmission circuit 120 in the first device 100 using capacitors C1 and C2, and the second contacts 210 and 212 in the second device 200 can be capacitively coupled to the second power transmission circuit 220 in the second device 200 using capacitors C3 and C4. The presence of capacitors used for this AC coupling or capacitive coupling can interrupt the DC current path between the first contacts 110, the second contacts 210, the device enclosure 1110 for the first device 100 (shown in Figure 11), and the device enclosure 1120 for the second device 200 (shown in Figure 11).

[0079] For example, a fluid or liquid may be present on some or all of the first contact 110, the second contact 210, the device enclosure 1110 for the first device 100, and the device enclosure 1120 for the second device 200. As part of an electrochemical corrosion process, the fluid can cause corrosion and induce ions to move into one or more of the fluids among the first contact 110, the second contact 210, the device enclosure 1110 for the first device 100, and the device enclosure 1120 for the second device 200. The movement of ions from the contacts to the fluid may be part of a loop involving a current moving from the contacts through the circuit of either the first or second device to ground. An input coupling capacitor can block the DC component of this current, thereby blocking the loop and slowing down the flow of ions from the contacts into the fluid. Further details are shown in the following diagram.

[0080] Figure 11 is a schematic diagram of a contact interface for the electronic system of Figure 1 according to one embodiment of the present invention. A first contact 110 can be coupled to an electrostatic discharge diode D1. The electrostatic discharge diode D1 may be a high-impedance, low-leakage diode. The first contact 110 can be coupled to a capacitor C1, and the capacitor C1 can be coupled to an inductor L1. The inductor L1 may be included to reduce the abrupt increase in current through the capacitor C1 when the first power transmission circuit 120 supplies power to the second power transmission circuit 220. The capacitor C1 can be selected to be large enough to provide low impedance to the differential output signal, but small enough to be physically reasonable. The inductor L1 can be selected such that the tuning frequency of the inductor L1 and capacitor C1 has a period shorter than the period of the differential output signal.

[0081] A liquid or fluid may be present on one or more of the first contact 110, the first contact 112, the device enclosure 1110, the second contact 210, the second contact 212, and the device enclosure 1120. As part of the electrochemical corrosion process, the fluid can induce corrosion and induce ions to move out of one or more of the first contact 110, the second contact 210, the device enclosure 1110, and the device enclosure 1210 into the fluid. The movement of ions can be facilitated by a current flowing from one of the first contact 110 or the second contact 210 through the circuit of either the first device 100 or the second device 200 to one of the device enclosures 1110 or the device enclosure 1120, which can then be grounded. This current flow can be driven, for example, by a galvanic voltage that may appear between the first contact 110 and the device enclosure 1110. For example, the first contact can be plated with gold or another conductive material, and the device enclosure 1110 can be made of steel, aluminum, or another material. These dissimilar materials can form a galvanic voltage between the first contact 110 and the device enclosure 1110. Input coupling capacitors C1 and C2 can block the DC component of this current from one of the first contacts 110 to the device enclosure 1110. Input coupling capacitors C3 and C4 can block the DC component of the current from one of the second contacts 210 to the device enclosure 1120.

[0082] In this example, capacitor C2 can be coupled to the first contact 112, electrostatic discharge diode D2, and inductor L2. Inductors L1 and L2 can be coupled to the inverter / rectifier circuit 1030. Diodes D1 and D2 may be the same or similar. Inductors L1 and L2 may be the same or similar. Coupling capacitor C3 can be coupled to the second contact 210, electrostatic discharge diode D3, and inductor L3. Diodes D1 and D3 may be the same or similar. Inductors L1 and L3 may be the same or similar. Coupling capacitor C4 can be coupled to the second contact 212, electrostatic discharge diode D4, and inductor L4. Diodes D1 and D4 may be the same or similar. Inductors L1 and L4 may be the same or similar. Inductors L3 and L4 can be coupled to the rectifier / inverter circuit 1040. The stray impedance between the first contact 110, the second contact 210, the device enclosure 1110 of the first device 100, and the device enclosure 1120 of the second device 200 can be modeled as resistors R1 to R7. Capacitors C1, C2, C3, and C4 may be the same or similar.

[0083] Various circuits can be used to implement power transmission circuits 120 and 220. An example is shown in the following figure.

[0084] Figure 12 is a simplified schematic of a portion of a power system circuit according to one embodiment of the present invention. In this example, switch 1010 (and switch 1060) may be implemented using transistor P1. Transistor P1 can connect battery 190 (or battery 290) to boost / buck circuit 1020 (or buck / boost circuit 1050). Transistor P1 is shown as a P-MOS transistor, but transistor P1 can be implemented in various ways, for example, by an N-MOS transistor, by two parallel transistors with a resistor in series with one of the two, or by other devices or circuits. Boost / buck circuit 1020 (and buck / boost circuit 1050) may be implemented using a single-input multiple-output (SIMO) architecture including inductor L1, transistors N1, N2, N3, and N4. The boost / buck circuit 1020 (or buck / boost circuit 1050) can be coupled to the inverter / rectifier circuit 1030 (or rectifier / inverter circuit 1040). The boost / buck circuit 1020 (and buck / boost circuit 1050) may have a full bridge architecture which may include transistors N5, N6, N7, and N8.

[0085] Figure 13 is a simplified schematic diagram of a partial replacement of a power system circuit according to one embodiment of the present invention. In these and other embodiments of the present invention, as shown in Figure 12, switch 1010 (and switch 1060) can be replaced by a circuit (not shown) which is a voltage and current limiter when receiving power and a current limiter when transmitting data. The boost / buck circuit 1020 (and buck / boost circuit 1050) can be implemented using a SEPIC-Cuk DC-DC converter including three inductors, inductor L1, inductor L2, and inductor L3. Transistors P1, N1, and N2 may be included together with capacitors C1, C2, C3, C4, and C5. The boost / buck circuit 1020 (and buck / boost circuit 1050) may have a full-bridge architecture which may again include transistors N5, N6, N7, and N8.

[0086] These and other embodiments of the present invention may include additional features that can help prevent or reduce corrosion. For example, they may include electrical impedance spectrometers. These circuits can provide a voltage waveform to one or more contacts of the device. The resulting voltage, the resulting current, or both can be measured. The resulting current may indicate that current is flowing through the liquid. The phase shift between the applied voltage waveform and the resulting current or resulting voltage may indicate the amount of the type of liquid. To prevent corrosion pathways, a coupling capacitor may be inserted between the contacts and the electrical impedance spectrometer. An example is shown in the following figure.

[0087] Figure 14 is a simplified circuit diagram of two power system circuit portions that transmit power according to one embodiment of the present invention. The inverter / rectifier circuit 1030 acts as an inverter and can provide a differential output signal to the first contact 110 via the switch 1420 and the coupling capacitor 1430. The coupling capacitor 1430 may include capacitors C1 and C2 from the contact interface in Figure 11. The second contact 210 can receive the differential output signal and provide it to the rectifier / inverter circuit 1040, which acts as a rectifier and can provide high and low voltages to the power factor correction controller 1450. The power factor correction controller 1450 can pass its output to the power management controller 1460, which can charge the battery 290. The power management controller 1460 can control the voltage and current seen by the battery 290 during charging. This path can be reversed if the second device 200 can charge the first device 100.

[0088] An electrochemical impedance spectroscopy (EIS) circuit 1470 may be included. The EIS circuit 1470 can provide a voltage waveform or a current waveform, but in this example, it can provide a voltage waveform. The voltage waveform can be a sine wave, a square wave, or other voltage waveform. The EIS circuit 1470 can be coupled to the first contact 110 via a coupling capacitor 1430. If liquid is present at one or more of the first contacts 110, the EIS circuit 1470 can be used to detect a current or voltage. The current, voltage, or both can indicate changes in capacitance and resistance observed at the first contacts 110. The EIS circuit 1470 can detect the magnitude of this current and voltage, as well as any phase shift compared to the applied voltage, and from there can be determined the changes in capacitance and resistance observed at the first contacts 110. From the changes in capacitance and resistance, information about the presence of liquid and the type of liquid present can be determined. Further details on this can be found in U.S. Patent No. 11658443, entitled "LIQUID DETECTION AND CORROSION MITIGATION," issued on 23 May 2023, which is incorporated by reference. Sources 1 and 2 can be used as voltage signals within the EIS circuit 1470.

[0089] Other types of circuits may be included in or associated with either or both of the power transmission circuits 120 and 220. For example, connection detection may be used to disconnect battery 190 or battery 290 when the opposing device is not mated. This connection detection may include sending a voltage ping from time to time at the first contact 110. This voltage ping should have the characteristic that the average value of the pings, or the average value of a set of pings, should be 0 volts.

[0090] Figures 15 to 17 show a contact assembly according to one embodiment of the present invention. In Figure 15, the contact assembly 1500 may include a contact 110 and a housing 1530. An insulator 1520 can form a seal between the contact 110 and the housing 1530 to prevent leakage into the device incorporating the contact assembly 1500.

[0091] The contact 110 can be formed from bulk or substrate 1510. Any plating layer 1512 can be formed on the bottom or inner surface of the contact 110. Any other plating can be formed along the sides of the bulk or substrate 1510. The bulk or substrate 1510 can be formed from stainless steel, titanium, tantalum, Inconel, nickel-aluminum bronze, copper, copper alloy, or other materials. The use of these materials can provide a contact that can be easily manufactured and can save valuable resources compared to contacts that can use exotic materials. These materials can provide good durability and corrosion resistance. Any plating layer 1512 can be formed from gold or other conductive materials; for example, any plating layer 1512 can be a gold flash. Any plating layer 1512 can form a surface that can be soldered to a flexible circuit board or other suitable substrate.

[0092] In these and other embodiments of the present invention, the voltage waveform transmitted by the contact 110 may be an AC waveform. Therefore, much of the current passing through the contact 110 can be transmitted on the surface of the contact 110. Accordingly, embodiments of the present invention can provide plating on part or all of the side surface 1514 of the bulk or substrate 1510. This plating can be gold, diamond-like carbon (formed to be conductive), titanium nitride, tin-silver, nickel-gold, or other materials. In these and other embodiments of the present invention, this plating can extend along part or all of the top and side surface of the bulk or substrate 1510. An example is shown in the following figures.

[0093] In Figure 16, the contact assembly 1600 may include a contact 110, a housing 1530, and an insulator 1520 that can form a seal between the contact 110 and the housing 1530. The contact 110 may include a bulk or substrate 1510 and an optional plating layer 1512 that can be plated with a finishing layer 1610. The finishing layer 1610 may be formed from diamond-like carbon (formed to be conductive), tin, tin-silver, nickel-gold, or other materials.

[0094] In Figure 17, the contact assembly 1700 may include a contact 110, a housing 1530, and an insulator 1520 that can form a seal between the contact 110 and the housing 1530. The contact 110 may include a bulk or substrate 1510, an optional plating layer 1512, a finish layer 1610, and an intermediate layer 1710. By adding the intermediate layer 1710, the need for the bulk or substrate 1510 to conduct the AC waveform is reduced. This makes it possible to use a low-conductivity or non-conductivity material such as plastic, ceramic, ceramic-plastic, aluminum, stainless steel, or other material as the bulk or substrate 1510. The intermediate layer 1710 may be gold, copper, nickel, or a combination thereof, or other conductive metal. The current generated by the AC waveform received by the contact 110 may be transmitted near the surface of the contact 110 due to the skin effect. Therefore, the intermediate layer may be relatively thin, for example, 10 to 100 microns, depending on the desired frequency range of the AC waveform. This thickness allows for good conductivity to AC waveforms.

[0095] The materials and various layers constituting the contact 110 can provide at least three functions. They can provide an interface function for mating with another contact, a conductive function for transmitting the charging AC waveform, and a mechanical function for providing a structure for the contact. In Figure 15, the bulk or substrate 1510 can provide a durable interface for mating with a contact on a second device. The conductivity of the bulk or substrate 1510 can be improved by adding an optional plating layer 1512 to the bottom and sides of the bulk or substrate 1510. The bulk or substrate 1510 can provide a mechanical function. In Figure 16, the interface function can be improved by adding a finishing layer 1610. The finishing layer 1610 can provide a surface with improved hardness and corrosion resistance. In Figure 17, the addition of an intermediate layer 1710 provides an opportunity to improve the conductive function of the contact 110 by including a layer of conductive material. In this case as well, by adding the intermediate layer 1710, the need to make the bulk or substrate 1510 conductive can be eliminated. This allows the bulk or substrate 1510 to be formed from a low-conductivity or non-conductivity material.

[0096] These functions can be assigned between these layers in different ways in different embodiments of the present invention. For example, in Figure 16, the finishing layer 1610 may have lower conductivity, and the bulk or substrate 1510 may have higher conductivity. In these and other embodiments of the present invention, two or more layers can be plated or otherwise formed on the bulk or substrate 1510.

[0097] The use of AC waveforms can allow the skin effect to be utilized. That is, the skin effect can allow the conductivity of the finish layer 1610 and the intermediate layer 1710 to depend on charge conduction. Such dependence on the finish layer 1610 and the intermediate layer 1710 may not be possible when power is transmitted using conventional DC voltage and current.

[0098] Unfortunately, the use of these plating layers can accelerate corrosion of these contacts 110. When connections are made using the contacts 110, the plating layers (such as the finishing layer 1610 and the intermediate layer 1710) and the substrate (such as the bulk or substrate 1510) can be damaged, which can lead to scratches, for example. Galvanic voltage can then appear across the scratches. The presence of electrolytes can also cause corrosion of the contacts 110.

[0099] Embodiments of the present invention may include various features to reduce galvanic corrosion that may be caused by scratches on the contact 110. For example, the materials for plating and the substrate can be selected to reduce any galvanic voltage. As an example, the plating of the contact can be gold with a galvanic voltage range of 0.07 to 0.2 V, and the bulk or substrate can be titanium with a galvanic voltage range of -0.12 to 0.04 V. Alternatively, the bulk or substrate may be a non-conductive material such as ceramic, plastic, or a combination of these or other materials.

[0100] In addition to reducing galvanic voltage in scratches, embodiments of the present invention can contact assemblies in a way that minimizes the opportunity for such scratches and other types of damage to occur. An example is shown in the following figure.

[0101] Figures 18A to 18D show profiles of contact assemblies according to one embodiment of the present invention. In Figure 18A, the first device may include a contact assembly 1810 that includes a contact 1812 surrounded by an adjacent insulator 1814 and housing 1816. The second device may include a contact assembly 1820 that includes a contact 1822 surrounded by an adjacent insulator 1824 and housing 1826. In this example, the contact 1812, insulator 1814, and housing 1816 are flush with each other, and the contact 1822 and insulator 1824 are flush with each other and movable relative to housing 1826.

[0102] The contact 1822 and insulator 1824 can move relative to the housing 1826 so that the contact 1822 can engage with the contact 1812. The contact assembly 1820 can mate with the contact assembly 1810 in the contact direction which is perpendicular or perpendicular to the surface of the contact 1822. Alternatively, the contact assembly 1820 can slide laterally across the contact assembly 1810 (or the contact assembly 1810 can slide laterally across the contact assembly 1820) until the contact 1822 is aligned with the contact 1812, at which point the contact 1822 and insulator 1824 can move toward the contact assembly 1810 so that the contact 1812 mates with the contact 1822.

[0103] When contact assemblies 1810 and 1820 engage in a vertical direction, contacts 1812 and 1822 are largely undamaged. However, when contact assembly 1820 moves laterally across contact assembly 1810 (or when contact assembly 1810 slides laterally across contact assembly 1820), contact 1822 interacts with housing 1816 and contact 1812, thereby potentially being damaged. Similarly, contact 1812 interacts with housing 1826, thereby potentially being damaged. This damage can lead to scratches. These scratches can expose galvanic connections and galvanic voltages between the various plating layers and substrates of contacts 1812 and 1822. These galvanic voltages, in the presence of an electrolyte, can cause corrosion on the surfaces of contacts 1812 and 1822.

[0104] In Figure 18B, the first device may include a contact assembly 1830 that includes a contact 1832 surrounded by an adjacent insulator 1834 and housing 1836. The second device may include a contact assembly 1840 that includes a contact 1842 surrounded by an adjacent insulator 1844 and housing 1846. In this example, the contact 1832, insulator 1834, and housing 1836 are flush with each other, and the contact 1842 may include an extension 1848 protruding from the insulator 1844. The contact 1842 and insulator 1844 are movable relative to the housing 1846.

[0105] The contact 1842 and insulator 1844 can move relative to the housing 1846 so that the contact 1842 can engage with the contact 1832. The contact assembly 1840 can mate with the contact assembly 1830 in the contact direction which is perpendicular or perpendicular to the surface of the contact 1842. Alternatively, the contact assembly 1840 can slide laterally across the contact assembly 1830 until the contact 1842 aligns with the contact 1832, at which point the contact 1842 and insulator 1844 can move toward the contact assembly 1830 so that the contact 1842 mates with the contact 1832.

[0106] When contact assemblies 1830 and 1840 engage in a vertical direction, contacts 1832 and 1842 are largely undamaged. However, when contact assembly 1840 moves laterally across contact assembly 1830 (or when contact assembly 1830 slides laterally across contact assembly 1840), the extension 1848 of contact 1842 interacts with housing 1836 and contact 1832, potentially causing damage. Similarly, contact 1832 interacts with housing 1846, potentially causing damage. This damage can lead to scratches. These scratches can expose galvanic connections and galvanic voltages between the various plating layers and substrates of contacts 1832 and 1842. These galvanic voltages, in the presence of an electrolyte, can cause corrosion on the surfaces of contacts 1832 and 1842.

[0107] In Figure 18C, the first device may include a contact assembly 1850 that includes a contact 1852 surrounded by an adjacent insulator 1854 and a housing 1856. The second device may include a contact assembly 1860 that includes a contact 1862 surrounded by an adjacent insulator 1864 and a housing 1866. In this example, the contact 1852 may be recessed relative to the housing 1856, and the insulator 1854 may be further recessed relative to the housing 1856. The contact 1862 may include an extension 1868 protruding from the housing 1866, and the insulator 1864 may include an extension 1869 protruding from both the housing 1866 and the contact 1862. The contact 1862 and the insulator 1864 are movable relative to the housing 1866.

[0108] The contact 1862 and insulator 1864 can move relative to the housing 1866 so that the contact 1862 can engage with the contact 1852. The contact assembly 1860 can mate with the contact assembly 1850 in the contact direction which is perpendicular or perpendicular to the surface of the contact 1862. Alternatively, the contact assembly 1860 can slide laterally across the contact assembly 1850 until the contact 1862 aligns with the contact 1852, at which point the contact 1862 and insulator 1864 can move toward the contact assembly 1850 so that the contact 1862 mates with the contact 1852.

[0109] When contact assemblies 1850 and 1860 engage in a vertical direction, contacts 1852 and 1862 suffer little damage. When contact assembly 1860 moves laterally across contact assembly 1850 (or when contact assembly 1850 slides laterally across contact assembly 1860), the extension 1858 of contact 1852 can interact with the extension 1869 of the insulator 1864, which may not cause significant damage. The extension 1868 of contact 1862 can be protected by the extension 1869 of the insulator 1864, thereby reducing damage to contact 1862.

[0110] In Figure 18D, the first device may include a contact assembly 1870 that includes a contact 1872 surrounded by an adjacent insulator 1874 and a housing 1876. The second device may include a contact assembly 1880 that includes a contact 1882 surrounded by an adjacent insulator 1884 and a housing 1886. In this example, the contact 1872 may be recessed relative to the housing 1876, and the insulator 1874 may be further recessed relative to the housing 1876. The contact 1882 may be flush with the insulator 1884, and both may be recessed relative to the housing 1886. The contact 1882 and the insulator 1884 are movable relative to the housing 1886.

[0111] Contact 1882 and insulator 1884 can move relative to housing 1886 so that contact 1882 can engage with contact 1872. Contact assembly 1880 can mate with contact assembly 1870 in the contact direction which is perpendicular or perpendicular to the surface of contact 1882. Alternatively, contact assembly 1880 can slide laterally across contact assembly 1870 until contact 1882 is aligned with contact 1872, at which point contact 1882 and insulator 1884 can move toward contact assembly 1870 so that contact 1882 mates with contact 1872. This movement can be facilitated by magnets 1879 in contact assembly 1870 and magnets 1889 in contact assembly 1880.

[0112] When contact assemblies 1870 and 1880 engage in a vertical direction, contacts 1872 and 1882 are hardly damaged. When contact assembly 1880 moves laterally across contact assembly 1870 (or when contact assembly 1870 slides laterally across contact assembly 1880), the extension 1878 of contact 1872 may not interact with contact assembly 1880 and thus may avoid damage. Contact 1882 is recessed and protected by the insulator 1884, thereby preventing damage.

[0113] Figure 19 shows a contact assembly for a contact interface according to one embodiment of the present invention. A first electronic device 1902 and a second electronic device 1904 can form an electronic system 1900. The first electronic device 1902 may include a contact assembly that includes a contact 1910 supported by an insulator 1930. The contact 1910 and the insulator 1930 can be located in a recess 1942 within the enclosure 1940 of the first electronic device 1902.

[0114] The second electronic device 1904 may include a contact assembly that includes a contact 1950 supported by an insulator 1960. The contact 1950 and the insulator 1960 can be positioned within an opening 1972 in the enclosure 1970 of the second electronic device 1904. The contact 1950 and the insulator 1960 can be moved to position within a recess 1942 in the enclosure 1940 of the first electronic device when the contact 1910 of the first electronic device 1902 mates with the contact 1950 of the second electronic device 1904.

[0115] Figure 20 shows further details of a contact assembly according to one embodiment of the present invention. The contact assembly 2000 may include two contacts 1950, each supported by an insulator 1960. The insulator 1960 may be supported by a beam 2010. The beam 2010 may be driven by a spring 2030 so that contact 1950 can engage with contact 1910 (shown in Figure 19). The beam 2010 may be pushed down by a aligning portion 2020. The aligning portion 2020 may align with a recess in a first electronic device 1902 (shown in Figure 19), allowing the spring 2030 to push contact 1950 and engage with contact 1910.

[0116] Figure 21 shows a contact assembly for a contact interface according to one embodiment of the present invention. A first electronic device 2102 and a second electronic device 2104 can form an electronic system 2100. The first electronic device 2102 may include a contact assembly that includes a contact 2110 supported by an insulator 2130. The contact 2110 and the insulator 2130 can be located in a recess 2142 within the enclosure 2140 of the first electronic device 2102.

[0117] The second electronic device 2104 may include a contact assembly that includes a contact 2150 supported by an insulator 2160. The contact 2150 and the insulator 2160 can be positioned within an opening 2172 in the enclosure 2170 of the second electronic device 2104. The contact 2150 and the insulator 2160 can be moved to position within a recess 2142 in the enclosure 2140 of the first electronic device when the contact 1910 of the first electronic device 2102 mates with the contact 1950 of the second electronic device 1904.

[0118] The contact 2150 may include two contact portions separated by an insulating portion 2162. The insulating portion 2162 may be a surface that can be subjected to abrasion to protect the exposed area of ​​the contact 2150. Similar to the extension 1869 of the insulator 1864 (shown in Figure 18C), the insulating portion 2162 may engage with the enclosure 2140 and contact 2110 of the first electronic device 2102 as the first electronic device 2102 and the second electronic device 2104 move laterally across each other during mating.

[0119] Figure 22 shows a cross-sectional side view of a contact assembly according to one embodiment of the present invention. The contact assembly 2200 may include a contact 2150 which can be supported by an insulator 2160. The contact 2150 and the insulator 2160 may be placed within an opening 2172 of an enclosure 2170. The enclosure 2170 may cover a housing 2230. The housing 2230 may include a hole 2232 for a spring 2210. The spring 2210 can be compressed as the first electronic device 2102 and the second electronic device 2104 (both shown in Figure 21) move laterally relative to each other during mating. Once the contact 2150 and the insulator 2160 are aligned with recesses 2142 of the enclosure 2140 (both shown in Figure 21), the spring 2210 can push the contact 2150 into the contact 2110. Signals received and provided on the contact 2150 may be transmitted by a conductor 2220. The conductor 2220 can be insulated with the insulator 2222.

[0120] Embodiments of the present invention can incorporate various features for limiting or reducing galvanic corrosion at the contacts of electronic devices. For example, the materials used for the contacts and housings can be selected to avoid differences in their galvanic voltages. Other DC voltages, such as DC offsets in the AC waveform used to transmit power, can be avoided or regulated to cancel out galvanic voltages between the materials used. DC conduction paths can also be blocked to limit electrochemical reactions that may lead to corrosion. An example is shown in the following figure.

[0121] Figure 23 shows a galvanic corrosion path in an electronic device according to an embodiment of the present invention. The electronic system 2300 may include a first electronic device 2302 and a second electronic device 2304. The first electronic device 2302 can supply AC power via capacitors C1 and C2 and a contact 2310. The contact 2310 may be insulated by an insulator 2320 and supported by a housing 2330.

[0122] In this example, ion paths may exist between the contacts 2310 and the housing 2330. For example, ion path 2380 may exist between the contacts 2310. Ion path 2385 may exist between each contact 2310 and the housing 2330. The AC nature of the waveform delivered over the contacts 2310 can alternate quickly enough to limit any electrochemical reaction. However, the presence of DC current, whether based on galvanic voltage, AC waveform offset, or otherwise, can trigger electrochemical reactions that may lead to corrosion.

[0123] Therefore, as shown in Figure 10, DC blocking capacitors C1 and C2 can be placed in series between the internal circuitry of the first electronic device 2302 and the contact 2310. Capacitors C1 and C2 can block DC currents that could otherwise lead to electrochemical reactions that could cause corrosion.

[0124] These and other embodiments of the present invention can further limit corrosion by further reducing the electric field between the contact 2310 and the housing 2330. For example, the material selected for the contact 2310, including any plating and material for the housing 2330, may be selected to reduce any galvanic voltage. As an example, the contact 2310 may be plated with gold having a galvanic voltage range of 0.07 to 0.2 V, and the housing may be titanium having a galvanic voltage range of -0.12 to 0.04 V.

[0125] These and other embodiments of the present invention can further reduce the galvanic voltage difference by selecting a non-conductive material for the housing. For example, the second electronic device 2304 may include a contact 2340 supported by a housing 2360. The contact 2340 may be a metallic area formed or plated on the housing 2360. The housing 2360 may be a non-conductive material such as plastic, ceramic, or a combination thereof or other materials.

[0126] The selection of a non-conductive material for the housing 2360 can reduce the ion path to the path 2380 between the contacts 2340. As a result, only one capacitor, shown here as capacitor C3, may be required to block the DC current flowing through path 2380. Using only one capacitor is more likely in the power receiving device, and the asymmetry caused by the absence of a second capacitor in the power supply device is not relevant.

[0127] In these and other embodiments of the present invention, it may be desirable for capacitors used, such as capacitors C1, C2, and C3, to fail in an open state in order to prevent the formation of a DC current path. Therefore, fail-open Y-type capacitors can be used as capacitors C1, C2, and C3.

[0128] Electrolytes are not always present in these and other types of electronic systems. Often, contact 2310 or other contacts are dry and lack liquid or other electrolytes. In such situations, power can be saved by transferring power in a DC manner. For example, inverter / rectifier circuits 1030 and 1040 (both shown in Figure 10) can be bypassed. An example is shown in the following figure.

[0129] Figure 24 shows an arbitrary DC charging in an electronic device according to an embodiment of the present invention. The electronic system 2400 may include a first electronic device 2402 and a second electronic device 2404. In the first electronic device 2402, the contact 2410 may be insulated by an insulator 2420 and supported by a housing 2430. In the second electronic device 2404, the contact 2440 may be supported by a non-conductive housing 2460 or plated onto the non-conductive housing 2460.

[0130] The first electronic device 2402 can be supplied with AC power via capacitors C1 and C2 and contact 2310. The first electronic device 2402 can be supplied with DC power via a closed switch S1 that can bypass capacitor C1 and via a closed switch S2 that can bypass capacitor C2, thereby connecting contact 2410 to a DC power source. Similarly, the second electronic device 2404 can receive power via capacitor C3 and can receive DC power by bypassing capacitor C3 via switch S3.

[0131] Switches S1, S2, and S3 may be desirable to have very high open-circuit impedances to prevent DC leakage in the presence of electrolytes at contacts 2410 and 2440. Therefore, embodiments of the present invention may utilize microrelays, micromechanical switches, or other types of switches. It should also be noted that many of the design considerations described herein may not provide contacts optimized for DC power transmission, and further compromises may be necessary.

[0132] Switches S1, S2, and S3 can each be controlled by a first electronic device 2402 or a second electronic device 2404. Switches S1 and S2 can be controlled by the first electronic device 2402, switch S3 can be controlled by the second electronic device 2404, or these switches can be controlled by other circuits. For example, the first electronic device 2402 can determine that contacts 2410 and 2440 are not exposed to the electrolyte and can close switches S1, S2, and S3 before supplying DC power. The second electronic device 2404 can determine that contacts 2410 and 2440 are not exposed to the electrolyte and can close switches S1, S2, and S3 before requesting DC power from the first electronic device 2402.

[0133] Here again, embodiments of the present invention may take measures to reduce or cancel out the DC electric field or DC voltage at the contacts of an electronic device. These measures can reduce the galvanic voltage as described above. They may also include reducing the DC offset of the AC waveform used when transferring data. They may also include using the DC offset of the AC waveform to cancel out the remaining galvanic voltage. They may also involve using the DC offset of the AC waveform which has been empirically or otherwise found to provide reduced corrosion. Examples of such waveforms are shown in the following figures.

[0134] Figure 25 shows an AC waveform for power transmission according to one embodiment of the present invention. Waveform 2500 may have a low voltage V2, a high voltage V1, and an average voltage V0. Waveform 2500 may have a rise time of Tr1 from V0 to V1 and remain at V1 for time T1. Waveform 2500 may have a fall time of Tf1 from V1 to V0 and a fall time of Tf2 from V0 to V2. Waveform 2500 may remain at V2 for time T2. Waveform 2500 may have a rise time of Tr2 from V2 to V0. Waveform 2500 may have a positive pulse width of Tp1 and a negative pulse width of Tp2. Filtering can be used to reduce the amount of harmonics present in the AC waveform 2500.

[0135] These rise times, fall times, high and low levels, and some or all of the other parameters may be adjustable. For example, the average voltage V0 can be varied. The average voltage V0 may be adjusted to be close to 0 in order to reduce any DC voltage generated by the differential AC waveform 2500. Alternatively, the average voltage V0 may be adjusted to a level that cancels out or compensates for the galvanic voltage present at the power transmission contacts. Alternatively, the average voltage V0 may be adjusted to a level that has been empirically or otherwise known to reduce corrosion at the power transmission contacts. Examples of circuits and methods that can be used are shown in the following figures.

[0136] Figure 26 shows a charging path through an electronic system according to one embodiment of the present invention. In this example, a first electronic device 2602 can supply power to a second electronic device 2604 in the electronic system 2600. A DC-DC converter 2610 can receive a DC input voltage DCIN, which may be a battery or other voltage. The DC-DC converter 2610 can set high voltage V1 and low voltage V2 (shown in Figure 25) for the AC waveform supplied from the inverter 2620 in the first electronic device 2602 to the rectifier 2630 in the second electronic device 2604. The rectifier 2630 can provide an output to a DC-DC converter 2640, which can provide an output voltage DCOUT.

[0137] In this example, voltages V1 and V2 may be programmable. Voltages V1 and V2 can be programmed so that the average voltage V0 (shown in Figure 25) approaches 0 in order to reduce any DC voltage generated by the differential AC waveform 2500. Alternatively, V1 and V2 can be programmed so that the average voltage V0 can be adjusted to a level that cancels out or compensates for the galvanic voltage present at the power transmission contacts. V1 and V2 can instead be programmed to provide an average voltage V0 that has been empirically or otherwise known to minimize corrosion.

[0138] In this example, voltages V1 and V2 can be provided in an open-loop manner. In these and other embodiments of the present invention, voltages V1 and V2 can be provided in a closed-loop manner. An example is shown in the following figure.

[0139] Figure 27 shows a charging path through an electronic system according to one embodiment of the present invention. In this example, a first electronic device 2602 can supply power to a second electronic device 2604 in the electronic system 2600. A DC-DC converter 2610 can receive a DC input voltage DCIN, which may be a battery or other voltage. The DC-DC converter 2610 can set high voltage V1 and low voltage V2 (shown in Figure 25) for the AC waveform supplied from the inverter 2620 in the first electronic device 2602 to the rectifier 2630 in the second electronic device 2604. The rectifier 2630 can provide an output to a DC-DC converter 2640, which can provide an output voltage DCOUT.

[0140] In this example, voltages V1 and V2 can be adjusted by a feedback path including a compensating circuit 2710 within the first electronic device 2602. Voltages V1 and V2 at the power transmission contacts of the inverter 2620 can be detected and provided to the compensating circuit 2710. Voltages V1 and V2 can be adjusted by the compensating circuit 2710 so that the average voltage V0 (shown in Figure 25) is close to 0 and any DC voltage generated by the differential AC waveform 2500 is reduced. Alternatively, V1 and V2 can be adjusted by the compensating circuit 2710 so that the average voltage V0 is adjusted to a level that cancels out or compensates for galvanic voltages present at the power transmission contacts. Alternatively, V1 and V2 can be adjusted by the compensating circuit 2710 to provide an average voltage V0 that has been empirically or otherwise known to minimize corrosion. The compensating circuit 2710 can be used to adjust the average voltage V0 by integrating the positive and negative pulses of the waveform 2500.

[0141] Figure 28 shows a charging path through an electronic system according to one embodiment of the present invention. In this example, a first electronic device 2602 can supply power to a second electronic device 2604 in the electronic system 2600. A DC-DC converter 2610 can receive a DC input voltage DCIN, which may be a battery or other voltage. The DC-DC converter 2610 can set high voltage V1 and low voltage V2 (shown in Figure 25) for the AC waveform supplied from the inverter 2620 in the first electronic device 2602 to the rectifier 2630 in the second electronic device 2604. The rectifier 2630 can provide an output to a DC-DC converter 2640, which can provide an output voltage DCOUT.

[0142] In this example, voltages V1 and V2 can be adjusted by a feedback path including a receive detection circuit 2810 in the second electronic device 2604 and an adjustment circuit 2820 in the first electronic device 2602. This can be done in various ways. In one example, voltages V1 and V2 at the power receiving contacts of the rectifier 2630 can be detected by the receive detection circuit 2810. This information can be transmitted to the adjustment circuit 2820. Voltages V1 and V2 can be adjusted by the adjustment circuit 2820 so that the average voltage V0 (shown in Figure 25) approaches 0 in order to reduce any DC voltage generated by the differential AC waveform 2500 (shown in Figure 25). In another example, the receive detection circuit 2810 can determine what adjustment should be made and provide that information to the adjustment circuit 2820. Alternatively, V1 and V2 can be adjusted by the adjustment circuit 2820 so that the average voltage V0 can be adjusted to a level that cancels out or compensates for the galvanic voltage present at the power transmission contacts. Alternatively, V1 and V2 can be adjusted by the adjustment circuit 2820 to provide an average voltage V0 that has been empirically or otherwise known to minimize corrosion. The receiver detection circuit 2810 can communicate with the adjustment circuit 2820 via power transmission contacts by transmitting an AC signal at a different frequency compared to the AC waveform 2500. The receiver detection circuit 2810 can communicate with the adjustment circuit 2820 via other wired, wireless, or other types of communication channels.

[0143] In these and other embodiments of the present invention, known patterns, which can be called training patterns, can be provided to the second electronic device 2604 by the first electronic device 2602. These known patterns can be used by the receive detection circuit 2810 in the second electronic device 2604 and the adjustment circuit 2820 in the first electronic device 2602 when adjusting the AC waveform provided to the second electronic device 2604 by the first electronic device 2602.

[0144] Data can be transmitted between the first electronic device 2602 and the second electronic device 2604 using an AC waveform. The frequency, phase, amplitude, or other characteristics of the AC waveform can be modulated to transmit the data. Other signals at other frequencies can be combined with the AC waveform using a diplexer, common-mode choke, or other circuitry. The data can be transmitted in the same direction as the power transmission, or power and data can be transmitted in different directions.

[0145] Various aspects of the differential AC waveform 2500 can be modified or adjusted based on the contact material, housing material, presence or absence of electrolyte, and any type of electrolyte present. An example of a method for determining the type of material used for the contacts is shown in the following figure.

[0146] Figure 29 shows data that may be used by a method for determining the type of material used in a contact according to one embodiment of the present invention. In this example, electrochemical impedance spectroscopy (EIS) curves are pre-generated for different materials in the absence of an electrolyte. Similar measurements can be performed immediately after connection between two electronic devices, where the absence of an electrolyte is likely to be high. These measurements can be performed at these times and other times when it is determined that no electrolyte is present.

[0147] The EIS curve measured by an electronic device can reflect the parallel combination of contacts in the measuring device and contacts in the mating device. The contacts in the measuring device can be known and stored during manufacturing. Using the measured EIS curve and known measuring device material, the contribution of parallel-mated device contacts to the EIS curve can be extrapolated. The extrapolated EIS curve of the mated device contacts can be compared to a previously measured curve, such as the one shown in this figure. From this, the material of the mated device contacts can be determined. These and other embodiments of the present invention do not require the generation of the entire curve. Instead, data points at several specific frequencies can be used.

[0148] Figure 30 shows a method for optimizing a charging waveform according to one embodiment of the present invention. In operation 3010 of method 3000, once a connection is formed, the first device can use EIS to determine the contact material of the second device. Such a method is outlined in Figure 29 above. Instead of using EIS, the first device can, in operation 3020, receive information about the contact material directly from the second device. The first device can collect other information during use. This information may include environmental and other information. For example, in operation 3030, the first device can receive EIS updates, depth, and other information from other sensors. In operation 3040, an optimized charging waveform can be determined. This charging waveform can, in operation 3050, be provided to the contacts of the first device for reception by the contacts of the second device.

[0149] Embodiments of the present invention may provide power transmission circuits and devices that can be placed in various types of devices such as portable computing devices, tablet computers, desktop computers, laptops, all-in-one computers, wearable computing devices, mobile phones, smartphones, media phones, storage devices, portable media players, navigation systems, monitors, power supplies, video distribution systems, adapters, remote control devices, chargers, and other devices.

[0150] Reference numbers are used consistently here across various figures.

[0151] It should be fully understood that the use of personally identifiable information should adhere to privacy policies and practices that are generally recognized as meeting or exceeding industry or government requirements for maintaining user privacy. In particular, personally identifiable information data should be managed and handled in a manner that minimizes the risk of unintended or unauthorized access or use, and the nature of authorized use should be clearly indicated to the user.

[0152] The above description of embodiments of the present invention is presented for illustrative and explanatory purposes only. It is not intended to be exhaustive or to limit the invention to the exact forms described, and many modifications and variations are possible in light of the above teachings. The embodiments have been selected and described in such a way as to best illustrate the principles of the present invention and its practical application, so that those skilled in the art may best utilize the invention in various embodiments and with various modifications suitable for specific uses that may be conceived. It will be understood that the present invention is intended to cover all modifications and equivalents within the following claims.

Claims

1. A power transmission circuit that supplies power from a first electronic device to a second electronic device, An inverter circuit that generates an alternating current (AC) charging waveform, An electrochemical impedance spectroscopy (EIS) circuit that provides the measurement, Equipped with, The measurement from the EIS circuit is used to detect the presence of an electrolyte at the contacts of the first electronic device, and if the presence of an electrolyte at the contacts of the first electronic device is detected, one or both of the frequency and amplitude of the AC charging waveform are adjusted. The aforementioned power transmission circuit is If the presence of an electrolyte at the contact of the first electronic device is detected, one or both of the frequency and amplitude of the AC charging waveform are adjusted, at least in part based on the measurement from the EIS circuit. The system is configured to provide the adjusted AC charging waveform to the second electronic device. Power transmission circuit.

2. A method for supplying power from a first electronic device to a second electronic device, The first electronic device is used to determine one or more parameters, wherein the one or more parameters include the presence of an electrolyte. Optimizing the AC charging waveform using one or more of the above parameters, To provide the optimized AC charging waveform to the second electronic device, Methods that include...

3. The method according to claim 2, wherein the AC charging waveform is partially optimized by adjusting the average of the AC charging waveform to compensate for the galvanic voltage of the first electronic device.

4. The method according to claim 3, wherein the AC charging waveform includes one of two bandwidth-limited inverse-phase square waves, two inverse-phase square waves, and two inverse-phase sine waves.

5. Battery and A switch connected to the aforementioned battery, A boost / back circuit coupled to the aforementioned switch, The inverter circuit coupled to the boost / buck circuit, wherein the inverter circuit is an inverter / rectifier circuit, A first capacitor coupled to the first output of the inverter / rectifier circuit, A second capacitor coupled to the second output of the inverter / rectifier circuit, The first contact connected to the first capacitor, The power transmission circuit according to claim 1, further comprising a second contact coupled to the second capacitor.

6. The power transmission circuit according to claim 5, wherein the first contact and the second contact are spring-biased contacts.

7. The power transmission circuit according to claim 6, wherein the first contact and the second contact each include an inclined coil spring.

8. The power transmission circuit according to claim 6, wherein the first contact and the second contact each comprise a stack of Belleville washers.

9. The power transmission circuit according to claim 6, wherein the first contact and the second contact each comprise two stacks of Belleville washers.

10. The power transmission circuit according to claim 5, wherein the first contact and the second contact are fixed contacts.

11. The power transmission circuit according to claim 5, wherein the switch is configured to disconnect the battery from the boost / back circuit when the power transmission circuit is not transmitting or receiving power.

12. The power transmission circuit according to claim 11, wherein the boost / back circuit increases the voltage from the battery and provides high and low voltages when the power transmission circuit is transmitting power.

13. The power transmission circuit according to claim 12, wherein the boost / back circuit reduces the voltage from the inverter / rectifier when the power transmission circuit is receiving power, thereby providing a charging voltage for the battery.

14. The power transmission circuit according to claim 13, wherein the inverter / rectifier circuit converts the high voltage and low voltage from the boost / buck circuit into differential output signals when the power transmission circuit is transmitting power.

15. The power transmission circuit according to claim 14, wherein the inverter / rectifier circuit rectifies the differential output signal when the power transmission circuit is receiving power.

16. The power transmission circuit according to claim 15, wherein the differential output signal includes two out-of-phase sine waves.

17. The power transmission circuit according to claim 15, wherein the differential output signal includes two square waves with opposite phases.

18. The power transmission circuit according to claim 15, wherein the differential output signal includes two bandwidth-limited, out-of-phase square waves.

19. The AC charging waveform is a differential output signal. The aforementioned power transmission circuit is A first capacitor coupled to the first output of the inverter circuit, A second capacitor coupled to the second output of the inverter circuit, The first contact connected to the first capacitor, The power transmission circuit according to claim 1, further comprising a second contact coupled to the second capacitor.

20. The power transmission circuit according to claim 19, wherein the differential output signal includes one of two bandwidth-limited inverse-phase square waves, two inverse-phase square waves, and two inverse-phase sine waves.

21. The measurement from the EIS circuit is used to determine the material of the contacts of the second electronic device, and one or both of the frequency and amplitude of the AC charging waveform are adjusted based on the material of the contacts of the second electronic device. The power transmission circuit according to claim 1.

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