Circuit for transmitting infrared signal through USB Type-C interface

Abstract

The utility model discloses a circuit for sending an infrared signal through a USB Type-C interface. An A5 pin and a B5 pin of the male head of the USB Type-C interface are grounded; the A6 pin receives a right channel audio signal transmitted by the electronic equipment; the A7 pin receives a left channel audio signal transmitted by the electronic equipment; one of the A8 pin and the B8 pin is called as a Mic + pin, and the other one is called as a Mic-pin. In the microphone connection sub-circuit, a first resistor is connected between a Mic + pin and a Mic-pin; and the second resistor is connected between the Mic-pin and the ground of the male head of the USB Type-C interface. In the signal conversion sub-circuit, an A7 pin of a male head of the USB Type-C interface is connected with a positive electrode of an infrared light emitting diode through a first diode; the A6 pin is connected with the positive electrode of the infrared light-emitting diode through a second diode; and the third resistor is connected between the negative electrode of the infrared light emitting diode and the Mic-pin. The remote control performance of infrared signals emitted by the device is stable, the product size is small, and the remote control distance and sensitivity are good.

Description

Technical Field

[0001] This application relates to a circuit that emits infrared signals. Background Technology

[0002] USB Type-C, also known as USB-C, is a hardware interface for the Universal Serial Bus (USB). A complete USB Type-C interface has 24 pins, 12 on each side. USB Type-C interfaces with reduced pin counts are commonly available, including 16-pin, 12-pin, 6-pin, 4-pin, and 2-pin versions.

[0003] Please see Figure 1 A complete USB Type-C female connector (socket) has 24 pins. In a clockwise direction, one side has pins A1 to A12, and the other side has pins B1 to B12.

[0004] Please see Figure 2 A complete USB Type-C male plug has 22 pins. In a counter-clockwise direction, one side has pins A1 to A12, and the other side has pins B1 to B12, with pins B6 and B7 being unused.

[0005] The USB Type-C interface has a working mode called audio adapter accessory mode. In this mode, pins A5 and B5 of the USB Type-C interface are grounded, and the USB Type-C interface is used to transmit audio signals. At this time, pins A6 and B6 are connected together to transmit the right channel audio signal; pins A7 and B7 are connected together to transmit the left channel audio signal; one of pins A8 and B8 transmits the microphone signal, and the other is grounded. The grounded pin (A8 or B8) serves as the return path for the right channel audio signal, the left channel audio signal, and the microphone signal.

[0006] Please see Figure 3 The working principle of a traditional infrared signal transmitting circuit is as follows: a low-frequency infrared remote control code is modulated onto a high-frequency carrier signal to obtain a high-frequency modulated signal. This high-frequency modulated signal is an electrical signal, which drives the infrared transmitting device to transmit infrared remote control signals of the same frequency (high frequency). Utility Model Content

[0007] The technical problem to be solved by this application is: how to enable electronic devices to transmit signals to the outside world and ultimately emit infrared signals through the USB Type-C interface.

[0008] To address the aforementioned technical problems, this application proposes a circuit for transmitting infrared signals via a USB Type-C interface, comprising a male connector of a full-pin USB Type-C interface, a microphone connection sub-circuit, and a signal conversion sub-circuit. The male connector of the full-pin USB Type-C interface is used to connect to a female connector of a full-pin USB Type-C interface on an electronic device; pins A5 and B5 of the male connector are grounded; pin A6 receives the right channel audio signal from the electronic device; pin A7 receives the left channel audio signal from the electronic device; one of pins A8 and B8 is designated as the Mic+ pin, and the other as the Mic- pin. In the microphone connection sub-circuit, a first resistor is connected between the Mic+ pin and the Mic- pin; a second resistor is connected between the Mic- pin and the ground of the male connector of the USB Type-C interface. In the signal conversion sub-circuit, pin A7 of the male connector of the USB Type-C interface is connected to the positive terminal of the infrared LED through a first diode; pin A6 is connected to the positive terminal of the infrared LED through a second diode; and a third resistor is connected between the negative terminal of the infrared LED and the Mic- pin.

[0009] Alternatively, the A6 and B6 pins of the male connector of the USB Type-C interface can be connected together to receive the right channel audio signal from the electronic device.

[0010] Alternatively, the A7 and B7 pins of the male connector of the USB Type-C interface can be connected together to receive the left channel audio signal from the electronic device.

[0011] Furthermore, when the input impedances of pins A8 and B8 of the male connector of the USB Type-C interface are equal, the resistance of the first resistor is zero.

[0012] Furthermore, when the female connector of the USB Type-C interface of the electronic device is in audio adapter accessory mode, and the pin between pins A8 and B8 is grounded, the resistance of the second resistor is zero.

[0013] Furthermore, in the signal conversion sub-circuit, the left channel audio signal is transmitted to the infrared LED through the first diode, and the right channel audio signal is transmitted to the infrared LED through the second diode.

[0014] Alternatively, a third resistor can be connected between the negative terminal of the infrared LED and the Mic+ pin.

[0015] Furthermore, when the current flowing through the infrared LED after removing the third resistor is less than the rated current of the infrared LED, the resistance of the third resistor is zero.

[0016] The technical advantages achieved by this application are: the infrared signal emitted by the circuit that sends infrared signals through the USB Type-C interface has stable remote control performance, small product size, and good remote control distance and sensitivity. Attached Figure Description

[0017] Figure 1 This is a complete pin diagram of the female connector of a USB Type-C interface.

[0018] Figure 2 This is a complete pin diagram of the male connector of a USB Type-C interface.

[0019] Figure 3 This is a schematic diagram illustrating the working principle of a traditional circuit that emits infrared signals.

[0020] Figure 4 This is a schematic diagram of the circuit proposed in this application for transmitting infrared signals via a USB Type-C interface.

[0021] Figure 5 This is a schematic diagram illustrating the working principle of the signal conversion sub-circuit of this application.

[0022] Figure 6 This is a schematic diagram illustrating the working principle of converting infrared signals into audio signals in this application.

[0023] The following are the labeling instructions in the diagram: 1 is the male connector of the USB Type-C interface with all pins; 2 is the microphone connection sub-circuit; and 3 is the signal conversion sub-circuit. Detailed Implementation

[0024] Please see Figure 4The circuit proposed in this application for transmitting infrared signals via a USB Type-C interface includes a male connector 1 of a full-pin USB Type-C interface, a microphone connection sub-circuit 2, and a signal conversion sub-circuit 3. The male connector 1 of the full-pin USB Type-C interface is used to connect to a female connector of a full-pin USB Type-C interface on an electronic device, and receives the left and right channel audio signals (both with the same frequency) transmitted from the electronic device in the audio adapter accessory mode of the USB Type-C interface. The microphone connection sub-circuit 2 is used to pull the A8 pin (SBU1 pin) and B8 pin (SBU2 pin) of the male connector 1 of the USB Type-C interface low. The signal conversion sub-circuit 3 is used to convert the left and right channel audio signals transmitted from the electronic device into pulse electrical signals (with a frequency twice that of the audio signals), and then emits infrared light signals.

[0025] Grounding pins A5 (CC1) and B5 (VCONN) of male connector 1 of the USB Type-C interface indicates that the USB Type-C interface is operating in audio adapter accessory mode. Pin A6 (D+) of male connector 1 of the USB Type-C interface receives the right channel audio signal, or pins A6 and B6 can be connected together to receive the right channel audio signal. Pin A7 (D-) of male connector 1 of the USB Type-C interface receives the left channel audio signal, or pins A7 and B7 can be connected together to receive the left channel audio signal. One of pins A8 and B8 of male connector 1 of the USB Type-C interface is called the Mic+ pin, and the other is called the Mic- pin. As an example, Figure 3 Pin A8 is used as the Mic+ pin, and pin B8 is used as the Mic- pin.

[0026] The microphone connection sub-circuit 2 includes a first resistor R1 and a second resistor R2. The first resistor R1 is connected between the Mic+ and Mic- pins of the male connector 1 of the USB Type-C interface. The first resistor R1 acts as an impedance balancing resistor between the Mic+ and Mic- pins. When the input impedances of pins A8 and B8 of the male connector 1 of the USB Type-C interface are equal, the resistance of the first resistor R1 is zero. The second resistor R2 is connected between the Mic- pin of the male connector 1 of the USB Type-C interface and ground (which can be any one or more of pins A1, A12, B1, and B12 of the male connector 1 of the USB Type-C interface). Figure 3The first resistor is exemplarily represented as pin B1. The second resistor R2 is the impedance balancing resistor between the Mic pin and ground. The resistance of the second resistor R2 is usually not zero. When the female connector of the USB Type-C interface of the electronic device is in audio adapter accessory mode, the pin between pins A8 and B8 that is grounded is allowed to be directly grounded (i.e., there is already impedance protection for direct grounding).

[0027] The signal conversion sub-circuit 3 includes a third resistor R3, a first diode D1, a second diode D2, and an infrared LED IR. Pin A7 of the male connector 1 of the USB Type-C interface is connected to the positive terminal of the infrared LED IR via the first diode D1, meaning the left channel audio signal is transmitted to the infrared LED IR through the first diode D1. Pin A6 of the male connector 1 of the USB Type-C interface is connected to the positive terminal of the infrared LED IR via the second diode D2, meaning the right channel audio signal is transmitted to the infrared LED IR through the second diode D2. The third resistor R3 is connected between the negative terminal of the infrared LED IR and the Mic- pin of the male connector 1 of the USB Type-C interface, or between the negative terminal of the infrared LED IR and the Mic+ pin. As an example, Figure 3 The third resistor R3 is connected between the negative terminal of the infrared LED IR and the Mic- pin. The third resistor R3 is a current-limiting resistor used to regulate the current flowing through the infrared LED IR. When the current flowing through the infrared LED IR is less than the rated current of the infrared LED IR after removing the third resistor R3, the resistance of the third resistor R3 can be zero.

[0028] The circuit proposed in this application for transmitting infrared signals via a USB Type-C interface is presented as an infrared remote control accessory. It is inserted into an electronic device (e.g., a mobile phone) with a full-pin USB Type-C female connector and works in conjunction with a driver program for converting infrared remote control codes to audio signals within the electronic device. The working principle of the infrared signal transmitting circuit in this application is as follows: Infrared remote control signals typically have a frequency greater than 30kHz, commonly 38kHz. When the electronic device wishes to transmit a high-frequency infrared remote control signal (e.g., 38kHz), the driver program first converts the low-frequency infrared remote control code into a dual-channel audio signal (with a frequency half that of the infrared remote control signal, e.g., 19kHz). Then, the dual-channel audio signal is transmitted through the full-pin USB Type-C female connector on the electronic device to the full-pin USB Type-C male connector 1 in the circuit described in this application, specifically transmitting the left and right channel audio signals. Subsequently, the signal conversion sub-circuit 3 in the circuit described in this application converts the dual-channel audio signal into a pulse electrical signal (the frequency is equivalent to the infrared remote control signal, for example, 38KHz), driving the infrared light-emitting diode to emit an infrared remote control signal of the same frequency (for example, 38KHz).

[0029] Please see Figure 5 Infrared remote control codes are typically a low-frequency sequence of high and low voltage levels. When the driver in an electronic device converts the infrared remote control code to an audio signal, it generates left and right channel audio signals of corresponding duration for the high-level portion of the code, and no left and right channel audio signals (i.e., zero) are generated for the low-level portion of the code. This is because the left and right channel audio signals differ by only half a cycle in phase. Figure 5 In short, it is represented as a signal.

[0030] Please see Figure 6The left and right channel audio signals are typically sine or cosine waves, with a 180-degree phase difference. For example, in the first half of a cycle, the left channel audio signal is positive and the right channel audio signal is negative; in the second half of the cycle, the left channel audio signal is negative and the right channel audio signal is positive. When the left channel audio signal is positive and the right channel audio signal is negative, the first diode D1 is turned on, the second diode D2 is turned off, and the left channel audio signal flows through the infrared LED IR and forms a loop through the Mic- pin. When the left channel audio signal is negative and the right channel audio signal is positive, the first diode D1 is turned off, the second diode D2 is turned on, and the right channel audio signal flows through the infrared LED IR and forms a loop through the Mic- pin. When the left and right channel audio signals are sine or cosine wave electrical signals with a frequency of 'a', the electrical signal flowing through the infrared LED IR is a pulse signal with a frequency of 2a. The infrared LED IR emits an infrared light signal with a frequency of 2a, effectively doubling the frequency. Please also refer to... Figure 5 In the infrared light signal (i.e., the infrared remote control signal), the high-level portion corresponding to the infrared remote control code consists of multiple continuous pulse signals, while the low-level portion corresponding to the infrared remote control code has no pulse signals. The physical meaning of these pulse signals is equivalent to the carrier signal in a traditional circuit that transmits infrared signals.

[0031] Compared with existing circuits for emitting infrared signals, this application has the following advantages.

[0032] First, this application converts the desired infrared remote control signal into a dual-channel audio signal, then transmits this dual-channel audio signal via a USB Type-C interface. Finally, a pulse electrical signal with twice the frequency is obtained from the dual-channel audio signal, which is then emitted as an infrared light signal by an infrared LED. The entire circuit of this application can function as an infrared remote control accessory. The detection mechanism of the USB Type-C interface easily identifies whether the infrared remote control accessory is inserted into an electronic device. The USB Type-C interface has a unified standard, and the output signal voltages of various manufacturers are standardized. The infrared remote control signal output by the circuit of this application has stable remote control performance and is suitable for commercial use.

[0033] Second, the resistors and diodes are extremely small, much smaller than the size of an infrared LED. This application uses only one infrared LED in its circuit, resulting in a small product size.

[0034] Third, the maximum audio sampling frequency of a typical mobile phone is 41kHz, which, according to Shannon's theorem for digital signals, can only generate a sine or cosine wave with a maximum frequency of 20.5kHz. Infrared remote control signals generally have frequencies greater than 30kHz, commonly around 38kHz. This application uses a 19kHz dual-channel audio signal in a mobile phone to carry a 38kHz infrared signal. Each channel's audio signal has its own loop, resulting in a superior remote control distance and sensitivity for the final output infrared signal.

[0035] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A circuit that transmits infrared signals via a USB Type-C interface, characterized in that, Includes a full-pin USB Type-C male connector, microphone connection sub-circuit, and signal conversion sub-circuit; The male connector of the full-pin USB Type-C interface is used to connect to the female connector of the full-pin USB Type-C interface on the electronic device; pins A5 and B5 of the male connector of the USB Type-C interface are grounded; pin A6 receives the right channel audio signal from the electronic device; pin A7 receives the left channel audio signal from the electronic device; one of pins A8 and B8 is called the Mic+ pin, and the other is called the Mic- pin. In the microphone connection sub-circuit, the first resistor is connected between the Mic+ pin and the Mic- pin; the second resistor is connected between the Mic- pin and the ground of the male connector of the USB Type-C interface. In the signal conversion sub-circuit, pin A7 of the male connector of the USB Type-C interface is connected to the positive terminal of the infrared LED through a first diode; pin A6 is connected to the positive terminal of the infrared LED through a second diode; and a third resistor is connected between the negative terminal of the infrared LED and the Mic- pin.

2. The circuit for transmitting infrared signals via a USB Type-C interface according to claim 1, characterized in that, or, the A6 pin and B6 pin of the male connector of the USB Type-C interface are connected together to receive the right channel audio signal transmitted from the electronic device.

3. The circuit for transmitting infrared signals via a USB Type-C interface according to claim 1, characterized in that, or, the A7 pin and B7 pin of the male connector of the USB Type-C interface are connected together to receive the left channel audio signal transmitted from the electronic device.

4. The circuit for emitting infrared signals via a USB Type-C interface according to claim 1, characterized in that, When the input impedances of pins A8 and B8 of the male connector of the USB Type-C interface are equal, the resistance of the first resistor is zero.

5. The circuit for emitting infrared signals via a USB Type-C interface according to claim 1, characterized in that, When the female connector of the USB Type-C interface of the electronic device is in audio adapter accessory mode, and the grounded pin of pins A8 and B8 is allowed to be directly grounded, the resistance of the second resistor is zero.

6. The circuit for emitting infrared signals via a USB Type-C interface according to claim 1, characterized in that, In the signal conversion sub-circuit, the left channel audio signal is transmitted to the infrared LED through the first diode, and the right channel audio signal is transmitted to the infrared LED through the second diode.

7. The circuit for emitting infrared signals via a USB Type-C interface according to claim 1, characterized in that, Alternatively, a third resistor can be connected between the negative terminal of the infrared LED and the Mic+ pin.

8. The circuit for emitting infrared signals via a USB Type-C interface according to claim 1, characterized in that, When the current through the infrared LED is less than the rated current of the infrared LED after the third resistor is removed, the resistance of the third resistor is zero.

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