Communication apparatus, system and method for a non-contacting slip ring optical communication system

Abstract

According to embodiments of this disclosure, a communication device, system, and method for a contactless slip ring optical communication system are provided. The communication device includes a transmitting circuit, a receiving circuit, an interface circuit, and an arbitration circuit. The transmitting circuit is configured to convert a first electrical signal into a first optical signal and transmit the first optical signal into free space within the contactless slip ring optical communication system. The receiving circuit is configured to, in response to receiving a second optical signal from free space, convert the second optical signal into a detection signal, generate a decision signal based on the voltage of the detection signal, and generate a second electrical signal based on the decision signal. The arbitration circuit is coupled to both the transmitting circuit and the receiving circuit, and is configured to, in response to receiving the decision signal from the receiving circuit, generate a locking signal to prevent the transmitting circuit from transmitting the first optical signal into free space.

Description

Technical Field

[0001] The exemplary embodiments disclosed herein generally relate to the field of communication technology, and particularly to communication devices, systems and methods for non-contact slip ring optical communication systems. Background Technology

[0002] Non-contact slip ring optical communication systems are used for data transmission between fixed and rotating components. Compared to contact-type data transmission devices, they offer advantages such as no wear, strong resistance to electromagnetic interference, and high data transmission rates. However, in half-duplex mode, traditional non-contact slip ring optical communication systems may experience issues where scattered or reflected light from the same-side optical transmitter is received by the same-side photodetector, creating a self-generating and self-retracting loop, leading to self-excitation, lock-up, or bus contention. Summary of the Invention

[0003] In a first aspect of this disclosure, a communication device for a non-contact slip ring optical communication system is provided. The communication device includes: a transmitting circuit configured to convert a first electrical signal into a first optical signal and transmit the first optical signal into free space within the non-contact slip ring optical communication system; a receiving circuit configured to, in response to receiving a second optical signal from free space, convert the second optical signal into a detection signal, generate a decision signal based on the voltage of the detection signal, and generate a second electrical signal based on the decision signal; an interface circuit coupled to both the transmitting and receiving circuits, configured to receive the first electrical signal from an external device of the communication device or transmit the second electrical signal to an external device; and an arbitration circuit coupled to both the transmitting and receiving circuits, configured to, in response to receiving the decision signal from the receiving circuit, generate a locking signal to prevent the transmitting circuit from transmitting the first optical signal into free space.

[0004] In a second aspect of this disclosure, a non-contact slip ring optical communication system is provided. The system includes: a stator and a rotor, the rotor being configured to rotate relative to the stator; and at least two communication devices according to a first aspect of this disclosure, with at least one communication device deployed on the stator and at least one communication device deployed on the rotor.

[0005] In a third aspect of this disclosure, a method is provided for a communication device in a contactless slip ring optical communication system. The method includes: converting the optical signal into a probe signal in response to receiving an optical signal from free space in the contactless slip ring optical communication system; and switching to a receiving mode in response to the voltage of the probe signal exceeding a reference voltage, in which the communication device is prohibited from transmitting optical signals into free space.

[0006] According to embodiments of this disclosure, the arbitration circuit generates a locking signal based on a decision signal generated by the receiving circuit. During the period when the locking signal is valid, the transmitting circuit is prohibited from transmitting optical signals into free space. This overcomes the problem of scattered or reflected light from the same-side optical transmitter being received by the same-side optical detector in half-duplex mode, thus forming a self-generating and self-returning loop. It can achieve mutual exclusion blocking with receiving priority and can effectively suppress self-excitation, locking, or bus competition caused by spatial scattering or reflection, which is beneficial to improving the stability and reliability of the non-contact slip ring optical communication system.

[0007] It should be understood that the content described in this section is not intended to limit the key or essential features of the embodiments of this disclosure, nor is it intended to restrict the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0008] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein: Figure 1 A schematic diagram of an example architecture of a non-contact slip ring optical communication system according to some embodiments of the present disclosure is shown; Figure 2 Example block diagrams of communication devices according to some embodiments of the present disclosure are shown; Figure 3 Example block diagrams of communication devices according to other embodiments of the present disclosure are shown; Figure 4 Example block diagrams of communication devices according to further embodiments of the present disclosure are shown; Figure 5 A timing diagram illustrating the generation of a locked window and mutual exclusion blocking according to some embodiments of the present disclosure is shown; Figure 6 An example circuit schematic of a receiving circuit according to some embodiments of the present disclosure is shown; Figure 7 An example circuit schematic of a transmitting circuit according to some embodiments of the present disclosure is shown; Figure 8 Example circuit schematics of transmitting circuits according to other embodiments of the present disclosure are shown; and Figure 9 A flowchart illustrating a process for a communication device in a non-contact slip ring optical communication system according to some embodiments of the present disclosure is shown. Detailed Implementation

[0009] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0010] In the description of embodiments of this disclosure, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The term "some embodiments" should be understood as "at least some embodiments". Other explicit and implicit definitions may also be included below.

[0011] As used in this disclosure, free space refers to the spatial region between the stator and rotor in a non-contact slip ring optical communication system through which optical signals are transmitted between stator-side and rotor-side communication devices.

[0012] As used in this disclosure, the term decision signal refers to a signal generated by the receiving circuit based on a comparison between the voltage of the probe signal and a reference voltage, used to characterize the reception status of the effective optical signal incident through free space on the other side.

[0013] As used in this disclosure, the term "lock signal" refers to a control signal generated by the arbitration circuit based on the decision signal after hysteresis shaping and / or hold filtering, used to control the mutual exclusion of the transmitting and receiving circuits.

[0014] As used in this disclosure, the term "lock window" refers to the time interval during which a lock signal is in an active state, during which communication devices are prohibited from transmitting light signals into free space.

[0015] As used in this disclosure, the term loopback refers to the phenomenon where an optical signal emitted by a phototransmitter on the same side is scattered and / or reflected and then received by a photodetector on the same side, which may lead to self-oscillation, lock-up, or bus contention.

[0016] As used in this disclosure, the term "nonlinear device" refers to a semiconductor device with nonlinear current-voltage characteristics, such as a Schottky diode, a PN junction diode, or a diode-connected bipolar transistor, used for dynamic clamping and / or limiting of the voltage at a bus node.

[0017] As used in this disclosure, the term "convergence node" refers to the node where the photocurrents generated by the photodetector converge to form a voltage signal.

[0018] As used in this disclosure, the term "reference node" refers to a node in a reference circuit used to generate a reference voltage, and the comparator circuit compares the voltage of the bus node with the voltage of the reference node to generate a decision signal.

[0019] Non-contact slip ring optical communication systems are used for data transmission between stationary and rotating components. Compared to contact-based data transmission devices such as conductive slip rings, non-contact slip ring optical communication systems offer advantages such as no wear, strong resistance to electromagnetic interference, and high data transmission rates. Non-contact slip ring optical communication systems can be applied in various scenarios, including rotary tables, medical equipment, robots, generators, and rotary joints.

[0020] However, several challenges remain in the engineering implementation of non-contact slip ring optical communication systems. First, the complex power supply and electromagnetic environment in industrial settings make the receiver susceptible to interference from high-current pulses from the transmitter and ambient light. Second, the optical path gap and alignment vary with mechanical structures and motion states, leading to a wide range of received light intensity, increased threshold drift, and a higher risk of misjudgment. Furthermore, in half-duplex mode, scattered or reflected light from the same-side transmitter may be received by the same-side photodetector, forming a self-generating and self-retracting loop, causing self-excitation, lock-up, or bus contention. Additionally, different industrial bus protocols (e.g., level-based single-ended or differential protocols versus direction-controlled differential protocols) have different transceiver control methods, resulting in complex interface adaptation.

[0021] Some consumer-grade infrared or visible light transceivers often employ fixed mute or echo suppression for the received output during transmission. However, these are primarily designed for short-range, relatively clean point-to-point communication and frequently rely on upper-layer protocol retransmission or master control intervention. For open optical paths or enclosed rotating cavities exposed to oil, dust, strong electromagnetic interference, and wide temperature variations, the above solutions are prone to dead zones, lock-up, or jitter, making it difficult to achieve transparent physical layer forwarding of industrial buses without introducing frame-level resolution delays.

[0022] Furthermore, in rotating cavities or semi-open optical paths, emitted light may undergo diffuse reflection and multipath propagation at surfaces such as walls, light-shielding structures, oily or dusty surfaces, forming optical echo energy with a certain duration and intensity varying with angle and gap. In contrast, transceiver control based on software or frame-level processing typically suffers from non-negligible processing and scheduling delays, easily triggering erroneous arbitration or forming loops before the echo has attenuated.

[0023] In view of this, embodiments of the present disclosure provide a communication device for a contactless slip ring optical communication system. The communication device includes a transmitting circuit, a receiving circuit, an interface circuit, and an arbitration circuit. The interface circuit is coupled to both the transmitting and receiving circuits, and can receive a first electrical signal from an external device. The transmitting circuit converts the first electrical signal into a first optical signal and transmits the first optical signal into free space within the contactless slip ring optical communication system. In response to receiving a second optical signal from free space, the receiving circuit converts the second optical signal into a detection signal, generates a decision signal based on the voltage of the detection signal, and generates a second electrical signal based on the decision signal. The second electrical signal can be transmitted to an external device via the interface circuit. The arbitration circuit is coupled to both the transmitting and receiving circuits, and in response to receiving the decision signal from the receiving circuit, the arbitration circuit generates a locking signal to prevent the transmitting circuit from transmitting the first optical signal into free space.

[0024] According to embodiments of this disclosure, the arbitration circuit generates a locking signal based on a decision signal generated by the receiving circuit. During the period when the locking signal is valid, the transmitting circuit is prohibited from transmitting optical signals into free space. This overcomes the problem of scattered or reflected light from the same-side optical transmitter being received by the same-side optical detector in half-duplex mode, thus forming a self-generating and self-returning loop. It can achieve mutual exclusion blocking with receiving priority and can effectively suppress self-excitation, locking, or bus competition caused by spatial scattering or reflection, which is beneficial to improving the stability and reliability of the non-contact slip ring optical communication system.

[0025] The following description, in conjunction with the accompanying drawings, details embodiments of this disclosure.

[0026] Figure 1 A schematic diagram of an example architecture 100 of a contactless slip ring optical communication system according to some embodiments of this disclosure is shown. Figure 1 As shown, the non-contact slip ring optical communication system may include a stator 120 and a rotor 130, the rotor 130 being rotatable relative to the stator 120. A free space 140 is defined between the stator 120 and the rotor 130. For example, the stator 120 and the rotor 130 may have a certain gap to form a free space 140 suitable for transmitting optical signals.

[0027] The stator 120 may be equipped with a first communication device 150, and the rotor 130 may be equipped with a second communication device 160. For ease of description, the first communication device 150, the second communication device 160, and other communication devices may be collectively referred to as communication device 110 or individually. Figure 2 As shown in the figure, the first communication device 150 and the second communication device 160 are examples of communication device 110. The first communication device 150 and the second communication device 160 transmit optical signals through free space 140, thereby realizing data communication between the stator 120 and the rotor 130.

[0028] In some embodiments, the first communication device 150 can convert an electrical signal from an external device into an optical signal and transmit the optical signal into free space 140. The second communication device 160 can receive the optical signal from free space 140, convert it into an electrical signal, and send it to the external device connected to the second communication device 160. Similarly, the second communication device 160 can also transmit an optical signal into free space 140, which is received by the first communication device 150 and converted into an electrical signal. In this way, the non-contact slip ring optical communication system can achieve bidirectional data transmission between the stator 120 and the rotor 130 without physical contact. It should be noted that the external device here refers to a device other than the communication device 110. The external device can be part of the non-contact slip ring optical communication system, such as an upstream or downstream device of the communication device 110. The external device can also be independent of the non-contact slip ring optical communication system, such as an upstream or downstream device coupled to the non-contact slip ring optical communication system. The embodiments of this disclosure do not limit this.

[0029] It should be understood that Figure 1 The non-contact slip ring optical communication system shown is merely exemplary, and the embodiments of this disclosure can be applied to various types of non-contact slip ring optical communication systems. For example, multiple communication devices 110 can be deployed on the stator 120 and rotor 130 respectively to improve the reliability and bandwidth of data transmission. Furthermore, the non-contact slip ring optical communication system can be applied to various application scenarios such as rotary tables, medical devices, generators, and rotary joints.

[0030] Figure 2 A block diagram of an example 200 of a communication device 110 according to some embodiments of the present disclosure is shown. The communication device 110 can be implemented as Figure 1 The first communication device 150 or the second communication device 160 shown. Figure 2 As shown, the communication device 110 may include an interface circuit 202, a transmitting circuit 204, an arbitration circuit 206, and a receiving circuit 210.

[0031] Interface circuit 202 is coupled to transmitting circuit 204 and receiving circuit 210, respectively. Interface circuit 202 can receive a first electrical signal from an external device of communication device 110. In some embodiments, interface circuit 202 may include an industrial communication physical layer transceiver, such as a physical layer transceiver conforming to the Controller Area Network (CAN) bus protocol, or a differential bus physical layer transceiver conforming to the TIA / EIA (Telecommunications Industry Association / Electronic Industries Alliance)-485 standard. Interface circuit 202 may have a bus-side differential port, a transmit data port, and a receive data port for connecting to an external CAN bus, RS-485 (Recommended Standard 485) bus, or other industrial bus.

[0032] Transmitting circuit 204 is coupled to interface circuit 202 to receive a first electrical signal from interface circuit 202. Transmitting circuit 204 is configured to convert the first electrical signal into a first optical signal and transmit the first optical signal into the free space 140 inside the contactless slip ring optical communication system. In some examples, transmitting circuit 204 is also coupled to arbitration circuit 206 to receive a locking signal from arbitration circuit 206. Specific implementation details of transmitting circuit 204 will be discussed below. Figure 7 and Figure 8 Provide a detailed description.

[0033] The receiving circuit 210 is configured to, in response to receiving a second optical signal from free space 140, convert the second optical signal into a detection signal, generate a decision signal based on the voltage of the detection signal, and generate a second electrical signal based on the decision signal. The receiving circuit 210 is coupled to the interface circuit 202 to transmit the second electrical signal to the interface circuit 202 and to an external device via the interface circuit 202. The receiving circuit 210 is also coupled to the arbitration circuit 206 to transmit the decision signal to the arbitration circuit 206. A detailed implementation of the receiving circuit 210 will be discussed below. Figure 6 Provide a detailed description.

[0034] Arbitration circuit 206 is coupled to both transmitting circuit 204 and receiving circuit 210. Arbitration circuit 206 is configured to generate a locking signal in response to receiving a decision signal from receiving circuit 210, thereby prohibiting transmitting circuit 204 from transmitting the first optical signal into free space 140. In this way, arbitration circuit 206 achieves a mutual exclusion blockade with reception priority. That is, when communication device 110 is receiving an optical signal from the other side, it prohibits its own side from transmitting an optical signal into free space 140, thereby suppressing spontaneous loops caused by spatial scattering or reflection.

[0035] In some examples, the communication device 110 may further include a configuration unit 208 coupled to an arbitration circuit 206. The configuration unit 208 is configured to enable the arbitration circuit 206 in response to a first instruction indicating that the communication device 110 is in a first communication mode (e.g., half-duplex mode). The configuration unit 208 is also configured to disable the arbitration circuit 206 in response to a second instruction indicating that the communication device 110 is in a second communication mode (e.g., full-duplex mode). In half-duplex mode, the arbitration circuit 206 is enabled, and loopback can be suppressed using the arbitration circuit 206. In full-duplex mode, the transmitting and receiving directions each employ two independent optical channels operating in parallel, allowing the arbitration circuit 206 to be bypassed or disabled.

[0036] By adopting the above technical solution, the communication device 110 can effectively suppress spontaneous loops caused by spatial scattering or reflection in half-duplex mode, while achieving efficient bidirectional data transmission in full-duplex mode. The arbitration circuit 206 generates a locking signal based on a decision signal, making the triggering of mutual exclusion blocking independent of parsing the frame structure of the communication protocol. This achieves transparent forwarding at the physical layer, reduces processing latency, and improves the real-time performance and determinism of communication.

[0037] Figure 3 A block diagram of an example 300 of a communication device 110 according to some embodiments of the present disclosure is shown. The communication device 110 may be... Figure 1 or Figure 2 Some specific implementations of the communication device 110 shown are as follows. Figure 3 As shown, the arbitration circuit 206 includes a first enable control circuit 302 and a logic gate circuit 304. In this case, the arbitration circuit 206 can also be referred to as, for example, a "logic-gated arbitration circuit".

[0038] The first enable control circuit 302 is coupled to both the receiving circuit 210 and the logic gate circuit 304. The first enable control circuit 302 is configured to generate a first lock signal in response to receiving a decision signal from the receiving circuit 210. The first input of the logic gate circuit 304 is coupled to the first enable control circuit 302, the second input of the logic gate circuit 304 is coupled to the interface circuit 202, and the output of the logic gate circuit 304 is coupled to the transmitting circuit 204. The logic gate circuit 304 can receive a first electrical signal from the interface circuit 202. If the first lock signal is received from the first enable control circuit 302, the logic gate circuit 304 stops transmitting the first electrical signal to the transmitting circuit 204. For example, the logic gate circuit 304 can perform logical operations on the first electrical signal and the first lock signal to determine whether to output the first electrical signal.

[0039] By employing logic-gated arbitration, the communication device 110 can implement mutual exclusion blocking in hardware logic. The propagation delay of its combinational logic path can be on the order of nanoseconds, enabling mutual exclusion blocking to be completed within a bit-level time scale, thus meeting the real-time and deterministic requirements of industrial buses.

[0040] In some embodiments, logic gate 304 may include one or a combination of multiple logic gates. As an example, logic gate 304 may include any one or a combination of AND gate, OR gate, NAND gate, NOR gate, or NOR gate. For instance, logic gate 304 may be implemented using a two-input NOR gate, performing a logical operation between the first electrical signal output from interface circuit 202 and a first locking signal, preventing the first electrical signal from driving the transmitting circuit 204 when the first locking signal is valid. In some examples, logic gate 304 may be implemented using discrete logic gates, or it may be implemented using programmable logic devices such as Complex Programmable Logic Devices (CPLDs) or Field-Programmable Gate Arrays (FPGAs). Of course, the above-described logic gate 304 is merely exemplary.

[0041] For example, interface circuit 202 may include a CAN physical layer transceiver, which can communicate with external devices via, for example, a CAN bus. The CAN physical layer transceiver may include a transmitting end (e.g., referred to as the TXD end) and a receiving end (e.g., referred to as the RXD end). The transmitting end of the CAN physical layer transceiver may be coupled to the receiving circuit 210, and the receiving end of the CAN physical layer transceiver may be coupled to the second input of logic gate 304. If the first enable control circuit 302 receives a decision signal from the receiving circuit 210, the first enable control circuit 302 sends a first locking signal to logic gate 304, for example, sending a high-level signal to the first input of logic gate 304. Logic gate 304 may, in response to the first locking signal, hardware interlock the coupling path between interface circuit 202 and transmitting circuit 204, preventing interface circuit 202 from coupling to transmitting circuit 204 through logic gate 304. In this way, the interface circuit 202 can be prevented from sending the first electrical signal to the transmitting circuit 204, thereby achieving the purpose of preventing the transmitting circuit 204 from sending optical signals to the free space 140.

[0042] Figure 4 A block diagram of an example 400 of a communication device 110 according to some embodiments of the present disclosure is shown. The communication device 110 may be... Figure 1 and Figure 2 Other specific implementations of the communication device 110 shown. For example... Figure 4As shown, the arbitration circuit 206 includes a second enable control circuit 402. In this case, the arbitration circuit 206 may also be referred to as, for example, an "enable pin controlled arbitration circuit".

[0043] The first input terminal 404 of the interface circuit 202 is configured to receive a first electrical signal from an external device. The first output terminal 406 of the interface circuit 202 is coupled to the transmitting circuit 204 and is configured to send the first electrical signal to the transmitting circuit 204. A second enable control circuit 402 is coupled to the control terminal of the interface circuit 202. If the second enable control circuit 402 receives a decision signal from the receiving circuit 210, it can send a second lock signal to the interface circuit 202 to disable the first input terminal 404 and / or the first output terminal 406 of the interface circuit 202. In this way, the interface circuit 202 can be prevented from receiving the first electrical signal from the external device via the first input terminal 404, or it can be prevented from sending the first electrical signal to the transmitting circuit 204 via the first output terminal 406, thereby preventing the transmitting circuit 204 from transmitting optical signals into free space 140.

[0044] As an example, such as Figure 4 As shown, the interface circuit 202 may include a differential physical layer transceiver, which may have a transmit enable terminal, a receive enable terminal, a first input terminal 404, a first output terminal 406, a second input terminal 410, and a second output terminal 408. The differential physical layer transceiver can be coupled to, for example, an industrial field (DP) bus or an RS-485 bus through the first input terminal 404, and the first output terminal 406 can be coupled to the transmitting circuit 204. The second input terminal 410 can be coupled to the receiving circuit 210, and the second output terminal 408 can be coupled to, for example, a DP bus or an RS-485 bus. The second enable control circuit 402 can be coupled to the transmit enable terminal and the receive enable terminal. If the second enable control circuit 402 receives a decision signal from the receiving circuit 210, the second enable control circuit 402 can send a second lock signal to the transmit enable terminal and the receive enable terminal to enable, for example, the second input terminal 410 and the second output terminal 408, and disable the first input terminal 404 or the first output terminal 406, thereby blocking the transmission of the first electrical signal to the transmitting circuit 204.

[0045] By employing an enable-controlled arbitration circuit, communication device 110 can be adapted to differential bus physical layer transceivers with direction control terminals, such as RS-485 transceivers, to achieve mutual exclusion blocking of the coupling path between interface circuit 202 and transmitting circuit 204. This approach is applicable to half-duplex differential bus protocols that require direction control.

[0046] In some embodiments, if the decision signal is interrupted and the interruption duration does not exceed a predetermined duration, the arbitration circuit 206 can maintain the lock signal. If the decision signal is interrupted and the interruption duration exceeds the predetermined duration, the arbitration circuit 206 can stop generating the lock signal. During the operation of the contactless slip ring optical communication system, a momentary drop in light intensity may occur due to echo attenuation or rotation modulation, causing a brief interruption of the lock signal. By delaying the release of the lock signal, the lock signal remains unchanged during the brief drop in the decision signal, thereby avoiding repeated switching of the mutual exclusion block in a short period of time and preventing self-oscillation or bus deadlock.

[0047] In some embodiments, the first enable control circuit 302 may include a holding circuit. The holding circuit is configured to generate a lock signal based on a sample-and-hold operation on a decision signal, the time constant of the holding circuit being greater than or equal to a predetermined multiple of the bit period. As an example, the holding circuit may include a semiconductor switching device, a resistor, and a capacitor. The semiconductor switching device may include, but is not limited to, a metal-oxide-semiconductor field-effect transistor (MOS transistor), a bipolar junction transistor (BJT), etc. The control terminal of the semiconductor switching device may be coupled to the receiving circuit 210, the input terminal of the semiconductor switching device may be coupled to a power supply, and the output terminal of the semiconductor switching device may be coupled to a reference node (e.g., ground) via a resistor. The first input terminal of the logic gate circuit 304 may be coupled between the input terminal of the semiconductor switching device and the resistor. The capacitor may be connected in parallel with the resistor. Thus, when the control terminal of the semiconductor switching device receives the decision signal, the semiconductor switching device turns on, sending a lock signal (e.g., a high-level signal) to the first input terminal. When the decision signal is interrupted, the capacitor can maintain the voltage at the first input terminal (i.e., maintain the lock signal).

[0048] In some embodiments, the predetermined multiple is greater than or equal to a first value, and the predetermined multiple is less than or equal to a second value. For example, the first value can be 0.8, and the second value can be 10. This means that the time constant of the holding circuit can be selected in the range of 0.8 times the bit period to 10 times the bit period to achieve a balance between suppressing jitter switching and reducing additional transmission suppression.

[0049] In some embodiments, the minimum duration of the locking signal falls within the range of a first number of bit cycles to a second number of bit cycles, and the predetermined duration is less than or equal to a third number of bit cycles. For example, the first number can be 0.8, the second number can be 20, and the third number can be 2. This means that the locking signal maintains a minimum locking duration of at least 0.8 to 20 bit cycles after being triggered, and is released after a release delay of no more than 2 bit cycles after the decision signal fails.

[0050] In some examples, the first enable control circuit 302 may include a hysteresis shaping circuit. The hysteresis shaping circuit is configured to generate a lock signal based on performing hysteresis shaping on the decision signal, and may be implemented, for example, using a Schmitt trigger. This also achieves the purpose of delaying the release of the lock signal. It should also be noted that the second enable control circuit 402 may also include, for example, a holding circuit or a hysteresis shaping circuit.

[0051] Figure 5 A timing diagram illustrating the generation of a locked window and mutual exclusion locking according to some embodiments of the present disclosure is shown. Figure 5 As shown, the horizontal axis of the timing diagram represents time. The timing diagram includes three signal waveforms: decision signal 502, lock signal 504, and enable signal 506. Enable signal 506 indicates the enabled state of the coupling path between interface circuit 202 and transmitting circuit 204, and is inversely related to lock signal 504. When lock signal 504 is high, enable signal 506 is low, indicating that the coupling path is disabled, and communication device 110 is prohibited from transmitting optical signals to free space 140. When lock signal 504 is low, enable signal 506 is high, indicating that the coupling path is enabled, and communication device 110 can transmit optical signals to free space 140.

[0052] The receiving circuit 210 generates a decision signal 502 based on a comparison between the voltage of the probe signal and the reference voltage. This decision signal characterizes the reception status of the effective optical signal incident from the opposite side via free space 140. The locking signal 504 is a control signal generated by the arbitration circuit 206 based on the decision signal 502 after hysteresis shaping and / or hold filtering. Figure 5 As shown, after the decision signal 502 transitions to a high level, the lock signal 504 also transitions to a high level. When the decision signal 502 briefly drops (i.e., transitions to a low level) between time points T1 and T2, the lock signal 504 remains high because the interruption time (T2-T1) does not exceed the predetermined duration. Correspondingly, the enable signal 506 remains low, and the coupling path is disabled. When the decision signal 502 transitions low again at time point T3, and the interruption duration (e.g., T4-T3) exceeds the predetermined duration, the lock signal 504 transitions low at time point T4. Correspondingly, the enable signal 506 switches to a high level, and the coupling path is enabled. This hysteresis characteristic ensures that the lock signal 504 remains unchanged when the decision signal 502 briefly drops, thereby preventing the mutual exclusion lock from repeatedly switching on and off within a short period of time.

[0053] By employing the aforementioned locking window generation mechanism, even if the decision signal 502 experiences a transient drop of no more than the preset drop width due to echo attenuation or light intensity jitter, the locking signal 504 remains valid. This prevents the mutual exclusion block from repeatedly switching on and off in a short period, thus avoiding self-excited oscillation or bus deadlock. This design is particularly suitable for scenarios involving diffuse reflection and multipath propagation in rotating cavities or semi-open optical paths.

[0054] Figure 6 A circuit schematic of an example 600 of a receiving circuit 210 according to some embodiments of the present disclosure is shown. Figure 6 The receiver circuit 210 shown can be Figure 2 Some specific implementations of the receiving circuit 210 shown are as follows. Figure 6 As shown, the receiving circuit 210 includes multiple detection branches, a first nonlinear device 614, a second nonlinear device 616, a filter capacitor 618, a second bias device 620, a first resistor 622, a comparator 624, a second capacitor 626, and an output resistor 628.

[0055] Multiple detection branches can be connected in parallel, with one end of each branch coupled to a power supply Vbias, and the other ends connected together to form a bus node 630. Each detection branch may include a photodetector, a first bias device, and a first capacitor. In one of the detection branches, the cathode of the photodetector can be coupled to the power supply Vbias via a corresponding first bias device. The photodetector is configured to generate a detection signal based on sensing a second optical signal in free space 140. The first bias device can provide a reverse bias for the photodetector. The cathode of the photodetector can also be coupled to a reference node via the first capacitor. The first capacitor acts as a decoupling capacitor, providing high-frequency isolation and suppressing the superposition of junction capacitances of parallel devices and noise mutual coupling.

[0056] In some embodiments, the photodetector may include, but is not limited to, a reverse-biased photodiode, phototransistor, or avalanche photodiode. The first biasing device may include a bias resistor or other biasing device, and the first capacitor may serve as a decoupling capacitor. As an example, such as... Figure 6As shown, the receiving circuit 210 may include a first detection branch and a second detection branch. The first detection branch may include a first photodiode 602, a first bias resistor 606, and a first decoupling capacitor 610. The cathode of the first photodiode 602 can be coupled to the power supply Vbias through the first bias resistor 606, and the cathode of the first photodiode 602 is also coupled to the reference node through the first decoupling capacitor 610. The anode of the first photodiode 602 can be coupled to the bus node 630. The second detection branch may include a second photodiode 604, a second bias resistor 608, and a second decoupling capacitor 612. The cathode of the second photodiode 604 can be coupled to the power supply Vbias through the second bias resistor 608, and the cathode of the second photodiode 604 can also be coupled to the reference node through the second decoupling capacitor 612. The anode of the second photodiode 604 can be coupled to the bus node 630.

[0057] Busbar 630 is a node where the photocurrents generated by multiple probe branches converge to form a voltage signal. A first nonlinear device 614 is connected between busbar 630 and the reference node, forming a nonlinear load. The first nonlinear device 614 is used to dynamically clamp and / or limit the voltage of busbar 630, thereby reducing overdrive at the comparator 624 input under strong light or ambient light interference conditions. The reference node provides a reference point; the reference node can be circuit ground or the negative terminal of the power supply, or it can be a node established under isolated power supply conditions that can provide a reference potential.

[0058] In some embodiments, the first nonlinear device 614 is configured to, in response to the light intensity of the second optical signal falling within a predetermined light intensity range, cause the voltage of the bus node 630 to fall within a predetermined voltage range and the current of the bus node 630 to fall within a predetermined current range. For example, within the normal communication received light intensity range, the voltage of the bus node 630 can be limited to between 0.1V and 0.8V, and / or the forward conduction current of the first nonlinear device 614 is between 10nA and 10mA.

[0059] In some examples, the first nonlinear device 614 can be a Schottky diode or an equivalent diode junction, whose exponential current-voltage characteristic can logarithmically compress the photocurrent within a certain operating range. When the bus node 630 is dominated by the first nonlinear device 614, the bus node voltage can be approximately expressed as: (1) in This indicates the voltage at bus node 630 (i.e., the bus node voltage), in volts (V). The ideality factor of the first nonlinear device 614 is dimensionless and typically ranges from 1.0 to 1.5. This represents thermal voltage, measured in volts (V). ,in Boltzmann constant ( ), Represents thermodynamic temperature (K). Indicates electron charge ( ), room temperature hour ; This represents the photocurrent generated by the incident light signal on multiple photodetectors, and is measured in amperes (A). The reverse saturation current of the first nonlinear device 614 is expressed in amperes (A). This represents the natural logarithm operator, which is dimensionless. This logarithmic relationship signifies the photocurrent induced by incident light. When the voltage variation over a large range is large, the variation amplitude of the bus node voltage is significantly compressed, thereby achieving greater overdrive resistance and dynamic range without introducing complex automatic gain control circuits.

[0060] The reference circuit is configured to generate a reference voltage. For example... Figure 6 As shown, the reference circuit includes a second nonlinear device 616, a filter capacitor 618, and a second bias device 620. One end of the second nonlinear device 616 is coupled to the power supply VCC through the second bias device 620, and the other end of the second nonlinear device 616 is coupled to a reference node (e.g., circuit ground) to form a reference node 632 between the second nonlinear device 616 and the second bias device 620. The filter capacitor 618 is connected in parallel with the second nonlinear device 616 to suppress high-frequency noise and stabilize the reference threshold.

[0061] In some embodiments, the first nonlinear device 614 may have a first temperature index, and the second nonlinear device 616 may have a second temperature index. The first temperature index indicates the variation (e.g., rate of change) of the electrical parameters of the first nonlinear device 614 with temperature, and the second temperature index indicates the variation (e.g., rate of change) of the electrical parameters of the second nonlinear device 616 with temperature. The first temperature index may be matched with the second temperature index so that the variation of the electrical parameters of the first nonlinear device 614 and the second nonlinear device 616 with temperature is the same or similar. In some examples, the first nonlinear device 614 and the second nonlinear device 616 may be selected as devices of the same type and with similar junction temperature characteristics, so that the temperature drift of the two junction voltages is reflected in a common-mode manner at the differential input of the comparator 624 and is canceled out, thereby improving the decision stability over a wide temperature range.

[0062] In some embodiments, the first nonlinear device 614 and the second nonlinear device 616 are both diodes, such as Schottky diodes, PN junction diodes, or diode-connected bipolar transistors. The first nonlinear device 614 and the second nonlinear device 616 can be packaged in the same device to form a thermally coupled pair, so that the clamping characteristics of the bus node 630 remain relatively consistent with the reference threshold as the temperature changes.

[0063] The comparator circuit is coupled to multiple photodetectors, a reference circuit, and an arbitration circuit 206, respectively. The comparator circuit is configured to generate a decision signal in response to a probe signal voltage exceeding a reference voltage. In some examples, such as... Figure 6 As shown, the comparator circuit includes a comparator 624, a first resistor 622, and a second capacitor 626. The first input terminal (e.g., the non-inverting input terminal) of the comparator 624 is coupled to the bus node 630 via the first resistor 622, and the second input terminal (e.g., the inverting input terminal) of the comparator 624 is coupled to the reference node 632. The first resistor 622 serves as an input isolation resistor to suppress input parasitics and ringing.

[0064] The second capacitor 626 is coupled to both the first input and output terminals of comparator 624. As a damping capacitor, the second capacitor 626 is connected between the output and first input terminals of comparator 624 to provide a high-frequency coupling path and suppress output ringing during the flip-flop of comparator 624, thereby reducing false triggering. The output terminal of comparator 624 is coupled to arbitration circuit 206 through output resistor 628, outputting a decision signal. Thus, receiving circuit 210 can achieve stable decision-making over a wide light intensity range and under ambient light interference, and improves the relative stability of the threshold through the temperature drift consistency of similar nonlinear devices, meeting the reliable communication requirements in industrial environments.

[0065] To avoid false triggering caused by near-field scattering and / or reflected light from the same-side optical transmitter, the threshold of reference node 632 is set between the "maximum busbar level corresponding to the same-side scattered or reflected light" and the "minimum busbar level corresponding to the effective incident light from the opposite side". Through this threshold windowing design, the decision signal mainly responds to the optical signal incident from the opposite side via free space 140, and will not remain in a triggered state for a long time due to same-side leakage from the local optical transmitter. This ensures the effectiveness of loop closure suppression arbitration while avoiding self-blocking of normal transparent forwarding.

[0066] It should be noted that the above-described receiving circuit 210 is merely exemplary. In practical applications, any other suitable circuit structure can be selected according to actual needs. For example, the receiving circuit 210 may also include one or more photodetectors. The embodiments of this disclosure do not limit the circuit structure of the receiving circuit 210.

[0067] Figure 7A circuit schematic of an example 700 of a transmitting circuit 204 according to some embodiments of the present disclosure is shown. The transmitting circuit 204 may be... Figure 2 Some specific implementations of the transmitting circuit 204 shown are illustrated. For example... Figure 7 As shown, the transmitting circuit 204 includes a driving circuit and a light emitter 706.

[0068] The driving circuit is coupled to the interface circuit 202 and is configured to generate a driving signal based on a first electrical signal from the interface circuit 202. The optical transmitter 706 is coupled to the driving circuit and is configured to generate a first optical signal and transmit the first optical signal into free space 140 in response to the driving signal.

[0069] like Figure 7 As shown, in some examples, the driving circuit may include a second resistor 702, a third capacitor 704, a semiconductor switching device 708, a third resistor 710, and a fourth capacitor 712. The input terminal of the light emitter 706 is coupled to the power supply through the second resistor 702. The second resistor 702 acts as a current-limiting resistor to limit the current flowing through the light emitter 706. The third capacitor 704 is connected in parallel with the second resistor 702 as a bypass capacitor to provide a transient current path at the moment the driving signal flips, shortening the equivalent charging and discharging time of the light emitter 706 and increasing the light pulse edge speed.

[0070] Semiconductor switching device 708 may include, but is not limited to, bipolar transistors or MOSFETs. The input terminal (e.g., collector) of semiconductor switching device 708 is coupled to the output terminal of light emitter 706, and the output terminal (e.g., emitter) of semiconductor switching device 708 is coupled to a reference node. A third resistor 710 is coupled to the control terminal (e.g., base) of semiconductor switching device 708 and is used to receive drive input signals. A fourth capacitor 712 is connected in parallel with the third resistor 710 as an accelerating capacitor, forming an edge injection branch to provide a fast charging and discharging path at the moment of level transition, thereby shortening the settling time of semiconductor switching device 708.

[0071] The transmitting circuit 204 can improve the optical pulse edge speed and reduce the limitation of communication bandwidth on low-cost light-emitting devices. The accelerating capacitor mainly acts on the control terminal of the semiconductor switching device 708, providing a fast charging and discharging path on the input side at the moment of level transition, thereby shortening the setup time of the semiconductor switching device 708. The bypass capacitor mainly acts on the load side of the optical transmitter 706, providing a transient low-impedance path on the load side at the moment of level transition to quickly inject and acquire dredged carriers, overcoming the limitations of junction capacitance and wiring parasitics of the optical transmitter 706. The two work together to form a transient drive, which can improve the optical pulse edge speed while maintaining steady-state current limiting and the reliability of the semiconductor switching device 708, thereby improving the available transmission rate and link margin under relative motion and coupling fluctuation conditions.

[0072] In some examples, the semiconductor switching device 708 may include a bipolar transistor. The driving circuit may also include a third nonlinear device 714 connected between the collector and base of the bipolar transistor. The third nonlinear device 714 can form an anti-saturation clamping branch between the collector and base of the bipolar transistor to reduce the storage effect caused by deep saturation and improve the turn-off speed.

[0073] In some examples, the drive circuit may also include a discharge path, one end of which may be coupled to the control terminal of the semiconductor switching device 708, and the other end of which may be coupled to a reference node (e.g., ground). The discharge path allows for the rapid discharge of charge from the control terminal of the semiconductor switching device 708. As an example, the discharge path may include a fourth resistor 716 and a first diode 718, and the control terminal of the semiconductor switching device 708 may be grounded via the fourth resistor 716 and the first diode 718 connected in series.

[0074] In some embodiments, the driving circuit may also be coupled to the arbitration circuit 206, and the driving circuit is further configured to stop generating a driving signal in response to a lock signal from the arbitration circuit 206, thereby limiting the generation of a first optical signal by the optical transmitter 706. Thus, when the arbitration circuit 206 generates a lock signal, the driving circuit stops driving the optical transmitter 706, thereby achieving a mutually exclusive blocking mechanism with priority for receivers.

[0075] Figure 8 A circuit schematic of example 800 of a transmitting circuit 204 according to other embodiments of the present disclosure is shown. Example 800 may be... Figure 2 Other specific implementations of the transmitting circuit 204 shown are as follows. Figure 8 As shown, the transmitting circuit 204 may include a plurality of first optical transmitters 802 and a plurality of second optical transmitters 804.

[0076] Multiple first light emitters 802 are connected in series to form a first branch, and multiple second light emitters 804 are connected in series to form a second branch. The first branch and the second branch are connected in parallel. The first branch is connected to the input terminal (e.g., the collector) of the semiconductor switching device 708 through a first current-limiting resistor 808, and a first bypass capacitor 806 is connected in parallel with the first current-limiting resistor 808. The second branch is connected to the input terminal of the semiconductor switching device 708 through a second current-limiting resistor 810. A second bypass capacitor 812 is connected in parallel with the second current-limiting resistor 810.

[0077] Multiple first optical transmitters 802 and multiple second optical transmitters 804 can be distributed circumferentially along the stator 120 or rotor 130 to form a ring or quasi-ring array. The emission coverage angle ranges of adjacent optical transmitters overlap, thereby reducing the optical coupling dead zone caused by relative motion. By dividing the multiple optical transmitters into at least two parallel branches, each branch is equipped with an independent current-limiting impedance and bypass capacitor, the current in each branch can be balanced and transient peaking current can be provided, improving the communication stability of the non-contact slip ring optical communication system during rotation.

[0078] In some embodiments, the arbitration circuit 206 may also control the controlled clamping device to transiently clamp the bus node of the receiving circuit 210 with dynamic threshold, or control the controlled disconnection, short-circuiting or reduction of the bias voltage of the photodetector bias path, so that the optical receiving front end is in a low-sensitivity state during local transmission, so as to further reduce the spontaneous transmission and reception interference caused by same-side scattered light or reflected light.

[0079] In rotating or relatively moving structures, the optical path attenuation, light-shielding structures, and mounting gaps of the stator 120 and rotor 130 may differ. To ensure consistent decision margins on both sides, the resistance values ​​of the second bias device 620 in the receiving circuit 210 of the first communication device 150 and the second bias device 620 in the receiving circuit 210 of the second communication device 160 may differ. In some examples, the resistance value of the second bias device 620 located at the stator 120 may be, for example, 28kΩ or other resistance values, and the resistance value of the second bias device 620 located at the rotor 130 may be, for example, 47kΩ or other resistance values, to balance response speed and sensitivity respectively.

[0080] To reduce coupling interference from high-current pulses on the transmitting side to the receiving decision, the communication device 110 can be powered by two power supplies. A higher voltage power supply (e.g., power supply VLED) powers the driver circuitry and the optical transmitter 706. A lower voltage power supply (e.g., power supply Vbias) powers the receiving circuitry 210. In some examples, the communication device 110 can accept a wide range of DC input (e.g., 9V to 36V) and generate an intermediate voltage rail (e.g., approximately 8V) and a logic voltage rail (e.g., approximately 5V) through linear regulation or other voltage regulation methods. Transient suppression devices, current limiting protection devices, and decoupling filter networks can be incorporated at the inputs to improve surge and electrostatic discharge resistance.

[0081] Figure 9 A flowchart of a process 900 for a communication device in a contactless slip ring optical communication system according to some embodiments of the present disclosure is shown. Process 900 can be implemented at the communication device 110 of any of the above embodiments.

[0082] In frame 910, communication device 110 converts an optical signal into a probe signal in response to receiving an optical signal in free space from a non-contact slip ring optical communication system.

[0083] In box 920, communication device 110 switches to receive mode in response to the voltage of the probe signal exceeding the reference voltage. In receive mode, the communication device is prohibited from transmitting light signals into free space.

[0084] In some examples, switching the receive mode includes: generating a decision signal in response to the voltage of the probe signal exceeding a reference voltage; generating a lock signal in response to the decision signal; and switching to receive mode in response to the lock signal.

[0085] In some examples, process 900 further includes: maintaining the lock signal in response to an interruption of the decision signal and the interruption duration not exceeding a predetermined duration; and / or stopping the generation of the lock signal in response to an interruption of the decision signal and the interruption duration exceeding a predetermined duration.

[0086] In some examples, generating the lock signal includes: generating the lock signal based on performing hysteresis shaping on the decision signal; or generating the lock signal based on performing sample-and-hold on the decision signal, wherein the time constant of the holding circuit is greater than or equal to a predetermined multiple of the bit period.

[0087] In some examples, the predetermined multiple is greater than or equal to the first value, and the predetermined multiple is less than or equal to the second value.

[0088] In some examples, the first value is 0.8 and the second value is 10.

[0089] In some examples, the minimum duration of the lock signal falls within the range of a first number of bit cycles to a second number of bit cycles, and the predetermined duration is less than or equal to a third number of bit cycles.

[0090] In some examples, the first number is 0.8, the second number is 20, and the third number is 2.

[0091] In some examples, process 900 further includes: enabling the arbitration circuit of the communication device in response to a first instruction, the first instruction indicating that the communication device is in a first communication mode; and / or disabling the arbitration circuit in response to a second instruction, the second instruction indicating that the communication device is in a second communication mode.

[0092] Various implementations of this disclosure have been described above. The foregoing description is exemplary and not exhaustive, nor is it limited to the disclosed implementations. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described implementations. The terminology used herein is chosen to best explain the principles, practical applications, or improvements to technology in the market, or to enable others skilled in the art to understand the implementations disclosed herein.

Claims

1. A communication device for a non-contact slip ring optical communication system, characterized in that, include: A transmitting circuit configured to convert a first electrical signal into a first optical signal and transmit the first optical signal into the free space inside the non-contact slip ring optical communication system; A receiving circuit configured to, in response to receiving a second optical signal from the free space, convert the second optical signal into a detection signal, generate a decision signal based on the voltage of the detection signal, and generate a second electrical signal based on the decision signal; An interface circuit is coupled to the transmitting circuit and the receiving circuit respectively, and the interface circuit is configured to receive the first electrical signal from an external device of the communication device or to send the second electrical signal to the external device. as well as An arbitration circuit, coupled to both the transmitting circuit and the receiving circuit, is configured to generate a locking signal in response to receiving a decision signal from the receiving circuit, thereby preventing the transmitting circuit from transmitting the first optical signal into the free space.

2. The communication device according to claim 1, characterized in that, The arbitration circuit is also configured to: In response to an interruption of the decision signal and the interruption duration not exceeding a predetermined duration, the lock signal is maintained; and / or In response to an interruption of the decision signal and an interruption lasting longer than the predetermined duration, the generation of the lock signal is stopped.

3. The communication device according to claim 2, characterized in that, The arbitration circuit includes: A hysteresis shaping circuit, coupled to the transmitting circuit and the receiving circuit, is configured to generate the locking signal based on performing hysteresis shaping on the decision signal; or A holding circuit configured to generate the lock signal based on performing a sample-and-hold operation on the decision signal, wherein the time constant of the holding circuit is greater than or equal to a predetermined multiple of the bit period.

4. The communication device according to claim 3, characterized in that, The predetermined multiple is greater than or equal to the first value, and the predetermined multiple is less than or equal to the second value.

5. The communication device according to claim 4, characterized in that, The first value is 0.8, and the second value is 10.

6. The communication device according to claim 2, characterized in that, The minimum duration of the locking signal falls within the range of a first number of bit cycles to a second number of bit cycles, and the predetermined duration is less than or equal to a third number of bit cycles.

7. The communication device according to claim 6, characterized in that, The first number is 0.8, the second number is 20, and the third number is 2.

8. The communication device according to claim 1, characterized in that, The arbitration circuit includes: A first enabling control circuit, coupled to the receiving circuit, is configured to generate a first locking signal in response to receiving the decision signal; and A logic gate circuit, wherein the first input terminal of the logic gate circuit is coupled to the first enable control circuit, the second input terminal of the logic gate circuit is coupled to the interface circuit, and the output terminal of the logic gate circuit is coupled to the transmitting circuit. The logic gate circuit is configured to stop sending the first electrical signal to the transmitting circuit in response to the first lock signal.

9. The communication device according to claim 1, characterized in that, The input terminal of the interface circuit is configured to receive the first electrical signal from the external device, the output terminal of the interface circuit is coupled to the transmitting circuit, and the output terminal of the interface circuit is configured to send the first electrical signal to the transmitting circuit. and The arbitration circuit mentioned above includes: A second enable control circuit is coupled to the control terminal of the interface circuit. The second enable control circuit is configured to send a second lock signal to the interface circuit in response to receiving the decision signal, thereby disabling the input and / or output terminals of the interface circuit.

10. The communication device according to claim 1, characterized in that, The receiving circuit includes: A photodetector configured to generate the detection signal based on sensing the second optical signal in the free space; Reference circuit, the reference circuit being configured to generate a reference voltage; and A comparator circuit, coupled to the photodetector, the reference circuit, and the arbitration circuit, is configured to generate the decision signal in response to a voltage exceeding the reference voltage of the detection signal.

11. The communication device according to claim 10, characterized in that, One end of the photodetector is coupled to a power supply via a first bias device, and the other end of the photodetector is coupled to a reference node via a first nonlinear device to form a bus node between the photodetector and the reference node. The comparator circuit is coupled to the bus node, wherein the reference node is configured to provide a reference voltage.

12. The communication device according to claim 11, characterized in that, One end of the photodetector is also coupled to the reference node via a first capacitor.

13. The communication device according to claim 11, characterized in that, The reference circuit includes a second nonlinear device and a second bias device. One end of the second nonlinear device is coupled to the power supply through the second bias device, and the other end of the second nonlinear device is coupled to the reference node to form a reference node between the second nonlinear device and the second bias device. The comparator circuit is coupled to the reference node.

14. The communication device according to claim 13, characterized in that, The first temperature index of the first nonlinear device is matched with the second temperature index of the second nonlinear device. The first temperature index indicates the variation of the electrical parameters of the first nonlinear device with temperature, and the second temperature index indicates the variation of the electrical parameters of the second nonlinear device with temperature.

15. The communication device according to claim 14, characterized in that, Both the first nonlinear device and the second nonlinear device are diodes.

16. The communication device according to claim 11, characterized in that, The first nonlinear device is configured to, in response to the light intensity of the second optical signal falling within a predetermined light intensity range, cause the voltage of the bus node to fall within a predetermined voltage range and the current of the bus node to fall within a predetermined current range.

17. The communication device according to claim 10, characterized in that, The comparison circuit includes a comparator, a first resistor, and a second capacitor. The first input terminal of the comparator is coupled to the photodetector through the first resistor, the second input terminal of the comparator is coupled to the reference circuit, the output terminal of the comparator is coupled to the arbitration circuit, and the second capacitor is coupled to both the first input terminal and the output terminal of the comparator.

18. The communication device according to claim 1, characterized in that, The transmitting circuit includes: A driving circuit, coupled to the interface circuit, is configured to generate a driving signal based on the first electrical signal from the interface circuit; and An optical transmitter coupled to the driving circuit, the optical transmitter being configured to generate the first optical signal and transmit the first optical signal into the free space in response to the driving signal.

19. The communication device according to claim 18, characterized in that, The driving circuit is also coupled to the arbitration circuit, and the driving circuit is further configured to stop generating the driving signal in response to the lock signal from the arbitration circuit, thereby limiting the optical transmitter from generating the first optical signal.

20. The communication device according to claim 18, characterized in that, The driving circuit includes a semiconductor switching device, a second resistor, a third resistor, a third capacitor, and a fourth capacitor. The input terminal of the light emitter is coupled to the power supply through the second resistor. The third capacitor is connected in parallel with the second resistor. The input terminal of the semiconductor switching device is coupled to the output terminal of the light emitter. The output terminal of the semiconductor switching device is coupled to a reference node. The third resistor is coupled to the control terminal of the semiconductor switching device. The fourth capacitor is connected in parallel with the third resistor.

21. The communication device according to claim 18, characterized in that, The optical transmitters are multiple, including multiple first optical transmitters and multiple second optical transmitters. The multiple first optical transmitters are connected in series to form a first branch, and the multiple second optical transmitters are connected in series to form a second branch. The first branch and the second branch are connected in parallel.

22. The communication device according to claim 1, characterized in that, The communication device also includes: A configuration unit coupled to the arbitration circuit is configured to enable the arbitration circuit in response to a first instruction, the first instruction indicating that the communication device is in a first communication mode, and the configuration unit is further configured to disable the arbitration circuit in response to a second instruction, the second instruction indicating that the communication device is in a second communication mode.

23. A non-contact slip ring optical communication system, characterized in that, include: A stator and a rotor, wherein the rotor is configured to rotate relative to the stator; as well as At least two communication devices as described in any one of claims 1 to 22, wherein the stator is provided with at least one of the communication devices and the rotor is provided with at least one of the communication devices.

24. A method for a communication device in a non-contact slip ring optical communication system, characterized in that, include: In response to receiving an optical signal from the free space of the non-contact slip ring optical communication system, the optical signal is converted into a detection signal; as well as In response to the voltage of the probe signal exceeding the reference voltage, the device switches to a receiving mode, in which the communication device is prohibited from transmitting light signals into the free space.

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