Bidirectional communication via capacitive coupling in a wireless device

Abstract

The present disclosure relates to two-way communication through capacitive coupling in a wireless device. Systems and methods for two-way communication through capacitive coupling are implemented using capacitor plates within the environment of a wireless power transfer system. Capacitance is used to transfer data on a path separate from power transfer in the wireless power transfer system.

Description

[0001] Cross - reference to related applications

[0002] None. Background Art

[0003] A wireless power transfer (WPT) system is formed by two main parts: a transmitter (TX) and a receiver (RX). The TX part (e.g., a stand) performs power conversion from a power source to an alternating current (AC) power signal with strict electrical characteristics such as amplitude, frequency, etc. The RX part (e.g., a barcode reader) performs power conversion from the AC power signal from the TX to a direct current (DC) power signal to supply to a load. However, for performing total contact replacement, no physical link is required between the TX side and the RX side. A two - way communication link needs to be established between the barcode reader and the stand holding the barcode reader to pair the two, so as to provide software updates for the barcode reader and send information in the case of foreign object detection (FOD).

[0004] In addition, an alternative to inductive coupling is needed to transfer power or transfer data independently of power transfer (e.g., between chips or within a chip). Summary of the Invention

[0005] The present Summary of the Invention is provided to introduce some concepts in a simplified form that will be further described in the Detailed Description below. The present Summary of the Invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] Embodiments of the present disclosure implement the use of capacitive coupling in a short - range two - way communication channel in a WPT system.

[0007] Embodiments of the present disclosure solve problems by bypassing conventional short - range communication protocols such as etc. and by having an auxiliary two - way communication channel that can be established by plates via capacitive coupling. These plates are respectively placed in a charging device (e.g., a stand, a charging pad, etc.) and a barcode reader (e.g., a handheld barcode reader, a mobile computer with barcode reading ability, a demonstration scanner, etc.), do not need to be aligned, and form the electrodes of a plate capacitor. Driving one of these plates with an electrical signal can cause a change in the electric field detected by the other plate. An adjustment stage connected to the plates can decode the transmitted signal.

[0008] The present disclosure stems from the need to perform physical contact replacement in a WPT system using a solution for two - way communication with the same performance as a wired connection. Embodiments of the present disclosure can achieve one or more of the following:

[0009] · Protect an alternative short - range two - way communication solution for wireless charging devices;

[0010] · Have a very low-cost solution (i.e., the cost of two operational amplifiers per board);

[0011] · Have a short-range communication channel that is completely independent of the wireless power channel, allowing communication to be established even in the absence of power transfer, such as during software updates or pairing;

[0012] · Have robust communication that is completely unaffected by metallic objects (i.e., metallic objects have a lattice formed by dipoles excited by electric field variations);

[0013] · Replace the physical layer of current communication protocols (such as IrDA) in terms of speed, input / output levels, and connectivity;

[0014] · Have good misalignment performance;

[0015] · Use the board as a presence sensor to activate the demo mode in a handheld scanner or to activate pairing between a charging device and a barcode reader; and

[0016] · Perform full-duplex communication.

[0017] In a first aspect, a system and method for bidirectional communication via capacitive coupling in a wireless charging device includes a wireless power transfer (WPT) system. The WPT system includes a first transceiver having transmission capabilities and a second transceiver having reception capabilities. The WPT system includes a pair of capacitor plates positioned between the first transceiver and the second transceiver. There is a distance between the first capacitor plate and the second capacitor plate of the pair of capacitor plates. The first transceiver sends an electrical signal to the first capacitor plate. The first capacitor plate and the second capacitor plate generate a capacitance that links the electrical signal from the first capacitor plate to the second capacitor plate. The electrical signal is received at the second transceiver from the second capacitor plate. The transfer of the electrical signal from the first transceiver through the first capacitor plate and from the second capacitor plate to the second transceiver occurs on a path separate from the transfer of power from the first transceiver to the second transceiver.

[0018] In a second aspect, a barcode reader has both wireless charging capabilities and short-range data communication capabilities. The barcode reader includes a wireless power charging receiver coil configured to be inductively coupled with a corresponding wireless power charging transmitter coil in a charging device to perform wireless power transfer therebetween. Capacitor plates are configured to be capacitively coupled with corresponding capacitor plates in the charging device to perform short-range data communication therebetween, and this short-range data communication is independent of the wireless power transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present disclosure is illustrated by way of example and not limitation in the accompanying drawings, in which like reference numerals indicate similar elements and in which:

[0020] Figure 1 is a schematic diagram of capacitive half - duplex communication implemented according to an embodiment of the present disclosure;

[0021] Figure 2 is a schematic diagram of capacitive full - duplex communication implemented according to an embodiment of the present disclosure;

[0022] Figure 3 is a view of board bipolar communication implemented according to an embodiment of the present disclosure;

[0023] Figure 4 is a schematic diagram of capacitive communication with a bipolar configuration implemented according to an embodiment of the present disclosure;

[0024] Figure 5 is a schematic diagram of a power and data system architecture implemented according to an embodiment of the present disclosure; and

[0025] Figure 6 is a process of two - way communication through capacitive coupling in a wireless charging device implemented according to an embodiment of the present disclosure. Detailed Description

[0026] The subject matter of aspects of the present disclosure is described herein in detail to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent.

[0027] In a WPT system, a two - way communication needs to be established between the TX and RX parts. These WPT systems can include both power (WPT) and communication (data) on separate, independent channels. However, the communication channel can be implemented on the same power channel via modulation techniques.

[0028] Embodiments of the present disclosure include a communication channel independent of the WPT channel, which can include capacitively - coupled boards and is configured for short - range two - way communication in a WPT system. Since the present disclosure is based on the physical phenomenon of capacitive coupling, the shape of the boards (e.g., rectangular, circular, etc.) and the nature of the dielectric (e.g., air, plastic, etc.) are not specified, and the physical phenomenon of capacitive coupling can be formed between boards of different shapes and different dielectric materials.

[0029] Although various shapes can be used, for simplicity, in embodiments of the present disclosure, a parallel - plate capacitor with an air - gap dielectric is used to describe capacitive coupling. The metal plates have a small surface area (e.g., mm 2) are separated from each other by approximately 10 - 20 mm. When electrical energy is supplied to one plate of the capacitor, an electric field is established between the two plates. The electric field creates a displacement current between the two plates, thereby transmitting energy. Generally, only a small amount of energy is required to transmit information only. This information transmission can be identified by the presence (e.g., logic level 1) or absence (e.g., logic level 0) of energy on the plate. This energy can be directly supplied by the input / output of the microcontroller or provided by a dedicated drive stage to have a stronger electric field, which results in better capacitive coupling.

[0030] In Figure 1 , embodiments of the present disclosure illustrate a WPT system 100. The capacitive link 102 is formed by at least two electrodes. To perform bidirectional communication, the transceiver 105 for the capacitor plate 110 and the transceiver 115 for the capacitor plate 120 are configured to energize the capacitor plate 110 during the transmission stage and collect and convert the charge present on the capacitor plate 120 during the reception stage. The communication flow (e.g., data transmission) is indicated by arrows 125 and 130.

[0031] Generally, only half - duplex communication may be possible because the two transceivers cannot transmit simultaneously. However, in Figure 2 , in the WPT system 200, two capacitive structures (202A and 202B) are configured to perform full - duplex communication. The capacitor plates 210A and 220A and the capacitor plates 210B and 220B can perform communication in one direction. For example, the capacitor plates 210A and 220A can perform communication 225, while the capacitor plates 210B and 220B can perform communication 230.

[0032] To construct full - duplex communication in a WPT system with a capacitive link, a bipolar configuration as shown in Figure 3 can be provided. The plate bipolar configuration 300 has a capacitor plate with two plate sides 310A and 310B. For example, Figure 3 the capacitor plate on the left shows the plate side 310A, while the capacitor plate shown on the right shows the plate side 310B. The plate sides 310A and 310B form a single capacitor plate. In other words, Figure 3 the plate sides 310A, 310B shown in Figure 1 can be understood as the opposite sides of the same capacitor plate. In an embodiment, the plate side 310A is the active plate side, and the plate side 310B is the grounded (GND) plate side. Thus, the plate side 310A can be referred to as the "active plate side" herein and the plate side 310B can be referred to as the "grounded plate side". The capacitor plates 110, 120 ( Figure 1 ), the capacitor plates 210A, 220A, 210B and 220B ( Figure 2 ), the capacitor plates 410, 420 ( Figure 4 ) and the capacitor plates 510, 520 ( Figure 5 ) can be as inFigure 3 formed as shown.

[0033] Using a pair of capacitor plates, the active plate sides 310A of each capacitor plate can be placed facing each other to form a differential capacitive coupling structure. This structure has noise immunity because the ground plate side 310B introduces boundary conditions for the electric field.

[0034] In an exemplary embodiment of the present disclosure, the capacitor plates can be formed of metal plates (e.g., copper) with dimensions of 6 mm × 2.3 mm and disposed on a support made of a composite material such as FR4. FR4 is a flame-retardant composite material and is made of glass fibers and epoxy resin. The copper plates can be spaced apart from a plastic material used as a dielectric by about 15 mm. The capacitance of the copper plates can be approximately 25 femto-Farads. However, the capacitance between the active plate side and the ground plate side can be about 1 - 2 pico-Farads. As a result, the optimal way to drive the active plates is to use a differential mode, which creates an alternating electric field for each pair of facing plates.

[0035] In Figure 4 the WPT system 400 is shown as having capacitor plates 410 and 420. Each of the capacitor plates 410 and 420 implements Figure 3 the plate sides in Figure 4 The capacitor plates 410 and 420 have an active plate side (310A) and a ground (GND) plate side (310B). As shown, two-way communication can occur between the capacitor plates 410 and 420. Both the capacitor plates 410 and 420 have at least two active plate sides on one side, as shown by the active plate side 310A. In an embodiment, the upper active plate side shows the communication flow in one direction, while the bottom active plate side shows the communication flow in the opposite direction. As understood, only the active plate side 310A in the plate 410 is fully visible. However, the capacitor plate 420 also has an active plate side 310A, but it is not visible in Figure 4 Similarly, the GND plate side 310B is fully visible in the capacitor plate 420. However, the capacitor plate 410 also has a GND plate side 310B, but it is not visible in

[0036] Because the architecture is symmetric, the architecture can be simplified to consider Figure 5 the communication flow from the first transceiver 505 to the second transceiver 515 in Figure 4 Compared with Figure 5 the architecture in Figure 5In the architecture, simulation can be performed, where the transceiver 505 has 3.3 V AC at a 100 kHz source, and this source excites the capacitor plate 510. This step is called the modulation stage. The source can be a dedicated driver or a microcontroller. Using the transceiver 515, charge variations can be collected between the capacitor plates 510 and 520. Such charge variations are converted into equivalent voltage variations. At this time, the demodulation stage appears in the transceiver 515. To design the demodulation stage in the simulation, the capacitance of the electrical model can be used, which includes a plate-to-plate capacitance of approximately 25 femtofarads between the capacitor plates 510 and 520 and a plate-to-ground capacitance of approximately 1 picofarad in each plate. The coupling second-order effect of the plate-to-plate cross capacitance between the capacitor plates 510 and 520 and the plate-to-plate capacitance on the same side may not need to be considered.

[0037] Using this simulation setup, the charge source model can generate a voltage variation of approximately 80 mV. To properly convert the charge, a charge amplifier converter operating at 100 kHz can be used. When executed, the simulation results are good in terms of shape and peak-to-peak amplitude. As the last step of the demodulation stage, an AC signal can be applied to a comparator with hysteresis to convert the analog signal into a digital signal. In the execution of the simulation, using aluminum foil as the dielectric between the capacitor plates 510 and 520 can produce the same result. The WPT system can be unaffected by metal objects.

[0038] Returning to Figure 5 , the WPT system 500 includes a power channel 540 and a data channel 530. The data channel 530 is illustrated as a short-range two-way communication channel occurring through capacitive coupling as evidenced by capacitor plates such as 510 and 520. The data channel 530 can be used to pair two parts in order to provide software updates for a barcode reader and / or send information in the case of foreign object detection (FOD).

[0039] In another embodiment of the present disclosure, the WPT system 500 can be configured with capacitor plates 510 and 520, which are placed near the wireless charging coils 550A and 550B. The wireless charging coils 550A and 550B are configured to perform wireless power transfer through inductive coupling. This embodiment shows that although the capacitor plates 510 and 520 are placed near the coils 550A and 550B, no interference occurs between power transfer and data communication. The reason for no interference is that there are two different physical principles at work, power transfer in the magnetic field and capacitive coupling in the electric field. Therefore, an embodiment that achieves space savings without loss of performance can be implemented.

[0040] Now turning to Figure 6, a process of two-way communication through capacitive coupling in a wireless charging device is provided in method 600. In step 605, wireless power transfer (WPT) system 500 includes a first transceiver 505 with transmitting capability and a second transceiver 515 with receiving capability. In step 610, capacitor plates 510 and 520 are positioned between the first transceiver 505 and the second transceiver 515. In step 615, the distance between the first capacitor plate 510 and the second capacitor plate 520 of the pair of capacitor plates is set. In step 620, an electrical signal is sent from the first transceiver 505 to the first capacitor plate 510. In step 625, a capacitance is generated between the first capacitor plate 510 and the second capacitor plate 520. In step 630, the electrical signal is received at the second transceiver 515 from the second capacitor plate 520, wherein the electrical signal sent to the first capacitor plate 510 is transferred from the first capacitor plate 510 to the second capacitor plate 520 according to the capacitance between the first capacitor plate 510 and the second capacitor plate 520. In step 635, the transfer of the electrical signal from the first transceiver 505 through the first capacitor plate 510 and from the second capacitor plate 520 to the second transceiver 515 occurs on a path separate from the transfer of power 540 from the first transceiver 505 to the second transceiver 515.

[0041] In summary, many different arrangements of the various components depicted and components not shown may be made without departing from the spirit and scope of the embodiments of the present disclosure. The embodiments of the present disclosure are described for illustrative rather than restrictive purposes. Certain features and sub-combinations are useful and may be used without reference to other features and sub-combinations and are considered to be within the scope of the claims.

Claims

1. A system for bidirectional communication by capacitive coupling in an inductive wireless charging device, comprising: A wireless power transfer (WPT) system (200, 400, 500) for power and data communication, comprising a first transceiver (105, 150, 505) with transmitting capability and a second transceiver (115, 515) with receiving capability; The WPT system (200, 400, 500) includes a first capacitor plate (210A, 410, 510) and a second capacitor plate (220A, 420, 520) positioned between the first transceiver (105, 150, 505) and the second transceiver (115, 515), where there is a distance between the first capacitor plate (210A, 410, 510) and the second capacitor plate (220A, 420, 520) of the pair of capacitor plates; and The first transceiver (105, 150, 505) is configured to send an electrical signal to the first capacitor plate (210A, 410, 510), causing capacitive coupling between the first capacitor plate (210A, 410, 510) and the second capacitor plate (220A, 420, 520), and where an electrical signal is received at the second transceiver (115, 515) from the second capacitor plate (220A, 420, 520), where data transfer from the first transceiver (105, 150, 505) through the first capacitor plate (210A, 410, 510) and from the second capacitor plate (220A, 420, 520) to the second transceiver (115, 515) occurs on a path separate from the transfer of power from the first transceiver (105, 150, 505) to the second transceiver (115, 515), where each of the first capacitor plate (410, 510) and the second capacitor plate (420, 520) has an active plate side (310A) and a ground plate side (310B), and each of the first capacitor plate (410, 510) and the second capacitor plate (420, 520) includes at least two active plates on the active plate side (310A) and a single ground plate on the ground plate side (310B); the active plate sides (310A) of the first capacitor plate (410, 510) and the second capacitor plate (420, 520) face each other and are configured to perform full-duplex communication.

2. The system according to claim 1, wherein, the first transceiver (105, 150, 505) and the first capacitor plate (210A, 410, 510) are located in the inductive wireless charging device that holds a barcode reader, and the second transceiver (115, 515) and the second capacitor plate (220A, 420, 520) are located in the barcode reader.

3. The system according to claim 1 or 2, wherein, the inductive wireless charging device is a stand.

4. The system according to claim 1 or 2, wherein, Each of the first capacitor plates (410, 510) and the second capacitor plates (420, 520) includes one or more metal plates disposed on a support formed of a composite material.

5. The system according to claim 4, wherein, for each of the first capacitor plates (410, 510) and the second capacitor plates (420, 520), the metal plates include the two active plates on the active plate side (310A) and the single ground plate on the ground plate side (310B).

6. The system according to claim 5, wherein, the two active plates are driven in a differential mode to generate an alternating electric field for each pair of facing plates.

7. The system according to claim 1 or 2, wherein, the first transceiver (105, 150, 505) includes both a transmission capability and a reception capability for data communication through the first capacitor plates and the second capacitor plates (210A, 410, 510, 220A, 420, 520), and the second transceiver (115, 515) includes both a reception capability and a transmission capability for data communication through the first capacitor plates and the second capacitor plates (210A, 410, 510, 220A, 420, 520).

8. The system according to claim 7, wherein, bi-directional communication occurs, wherein data is transmitted in one direction from the first transceiver (115, 515) through the first capacitor plates (210A, 410, 510) to the second capacitor plates (220A, 420, 520) and from the second capacitor plates (220A, 420, 520) to the second transceiver (115, 515), and data is transmitted in the other direction from the second transceiver (115, 515) through the second capacitor plates (220A, 420, 520) to the first capacitor plates (210A, 410, 510) and from the first capacitor plates (210A, 410, 510) to the first transceiver (115, 515).

9. A barcode reader having both wireless charging capability and short-range data communication capability, the barcode reader comprising: a second transceiver (115, 515) having a reception capability for power and data communication, including a wireless power charging receiver coil (550B), the wireless power charging receiver coil (550B) being configured to be inductively coupled to a corresponding wireless power charging transmitter coil (550A) in the first transceiver (105, 150, 505) of a charging device to perform wireless power transfer therebetween; and A second capacitor plate (220A, 420, 520) configured to be capacitively coupled to a corresponding first capacitor plate (210A, 410, 510) in the charging device to perform short-range data communication therebetween independent of the wireless power transfer, wherein the second transceiver (115, 515) is configured to receive, from the second capacitor plate (220A, 420, 520), an electrical signal transmitted from the first transceiver (105, 150, 505) to the first capacitor plate (210A, 410, 510); wherein the second capacitor plates (420, 520) have an active plate side (310A) and a ground plate side (310B), the second capacitor plates (420, 520) include at least two active plates on the active plate side (310A) and a single ground plate on the ground plate side (310B); the active plate side (310A) of the second capacitor plates (420, 520) is configured to perform full-duplex communication with a corresponding active plate side (310A) of the first capacitor plates (410, 510) in the charging device.

10. A method for two-way communication by capacitive coupling in a wireless charging device, comprising: operating a wireless power transfer WPT system for power and data communication, the system including a first transceiver (105, 150, 505) having a transmitting capability and a second transceiver (115, 515) having a receiving capability; positioning a pair of capacitor plates between the first transceiver (105, 150, 505) and the second transceiver (115, 515), wherein there is a distance between a first capacitor plate (210A, 410, 510) and a second capacitor plate (220A, 420, 520) of the pair of capacitor plates; transmitting an electrical signal from the first transceiver (105, 150, 505) to the first capacitor plate (210A, 410, 510), wherein transmitting the electrical signal includes generating a capacitance between the first capacitor plate (210A, 410, 510) and the second capacitor plate (220A, 420, 520); and receiving, at the second transceiver (115, 515), the electrical signal from the second capacitor plate (220A, 420, 520), wherein the electrical signal transmitted to the first capacitor plate (210A, 410, 510) is transferred from the first capacitor plate (210A, 410, 510) to the second capacitor plate (220A, 420, 520) according to the capacitance between the first capacitor plate (210A, 410, 510) and the second capacitor plate (220A, 420, 520), Among them, the transmission of the electrical signal from the first transceiver (105, 150, 505) through the first capacitor plate (210A, 410, 510) and to the second transceiver (115, 515) from the second capacitor plate (220A, 420, 520) occurs on a path separate from the transmission of power from the first transceiver (105, 150, 505) to the second transceiver (115, 515). Among them, each of the first capacitor plate (410, 510) and the second capacitor plate (420, 520) has an active plate side (310A) and a ground plate side (310B), and each of the first capacitor plate (410, 510) and the second capacitor plate (420, 520) includes at least two active plates on the active plate side (310A) and a single ground plate on the ground plate side (310B); and the method further includes performing full-duplex communication between the active plate side (310A) of the first capacitor plate (410, 510) and the active plate side (310A) of the second capacitor plate (420, 520).

11. The method according to claim 10, further comprising positioning the first transceiver (105, 150, 505) and the first capacitor plate (210A, 410, 510) in the wireless charging device that holds the barcode reader, and positioning the second transceiver (115, 515) and the second capacitor plate (220A, 420, 520) in the barcode reader.

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