Signal transmission method of photoelectric emitter based on liquid crystal shutter

Abstract

The invention relates to the technical field of photoelectric transmission, and discloses a signal transmission method of a photoelectric emitter based on a liquid crystal shutter, which modulates a sound signal through the liquid crystal shutter, and directly detects an optical signal by adopting a solar cell panel, so that the structure of photoelectric transmission receiving equipment is remarkably simplified, and the manufacturing cost and the maintenance difficulty are reduced; the design is intuitive and easy to understand, a user can easily operate without complex professional skills and knowledge, and the use convenience and universality are greatly improved; through the design of the signal filter circuit, the differential amplifier circuit and the like, unnecessary frequency components are effectively filtered out, the signal amplification effect is enhanced, and therefore the definition and quality of transmitted sound signals are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric transmission, and in particular to a signal transmission method of a photoelectric transmitter based on a liquid crystal shutter. Background Art

[0002] Photoelectric transmission is a technology that uses light as an information carrier to transmit information. It achieves information transmission by converting electrical signals into optical signals, then transmitting the optical signals to the destination using transmission media such as optical fibers, and then converting the optical signals back into electrical signals. Photoelectric transmission technology has been widely used in the field of modern communications due to its high speed, large capacity, low attenuation, and strong anti-interference ability.

[0003] Although photoelectric transmission technology has many advantages, there are still some problems and challenges in practical applications. Traditional photoelectric transmission receiving test equipment is usually complex in structure, which increases the cost and maintenance difficulty of the equipment. At the same time, the complex structure also leads to inconvenience in operation, requiring users to have high professional skills and knowledge when using it. Therefore, a signal transmission method of a photoelectric transmitter based on a liquid crystal shutter is proposed. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a signal transmission method of a photoelectric transmitter based on a liquid crystal shutter to solve the background technical problems.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a signal transmission method of a photoelectric transmitter based on a liquid crystal shutter, a photoelectric transmitter is designed based on the electro-optical effect of liquid crystal, the transmitter uses a liquid crystal shutter to modulate a sound signal, and the amount of light passing through the device is modulated by controlling the voltage applied to the liquid crystal shutter, thereby realizing wireless transmission of the sound signal;

[0006] Design a receiver for detecting changes in light intensity emitted by a photoelectric transmitter, which uses a solar panel to directly detect the light signal and convert it into an electrical signal;

[0007] Post-processing of the converted electrical signal, including amplification and filtering, to reconstruct the transmitted sound signal;

[0008] Both the transmitter and receiver are equipped with corresponding circuit designs, including transmitter amplification design, signal filtering circuit, microphone / audio dual-channel input design, and receiver preamplifier and audio amplifier design;

[0009] The transmitter amplification design includes a differential amplifier circuit to process and amplify the incoming sound signal;

[0010] The signal filtering circuit is designed to filter out unwanted frequency components to ensure the clarity and quality of the transmitted sound signal;

[0011] The microphone / audio dual input design allows users to input sound signals through a microphone or audio jack;

[0012] The receiver preamplifier design uses an inverting amplifier circuit to achieve variable gain, amplifying the received weak signal to increase the signal strength;

[0013] The receiver audio amplifier design includes a gain control circuit, a low-pass filter circuit, and a bass enhancement circuit to adjust the volume, sound quality, and bass effect of the output sound;

[0014] The modulated optical signal is transmitted wirelessly via visible light (such as the light emitted by a flashlight). By controlling the intensity and direction of the transmitter's optical signal and the direction and position of the receiver, the transmission distance between the transmitter and the receiver and the receiver's sensitivity to the optical signal can be met.

[0015] Preferably, the liquid crystal shutter is made of nano-polymer dispersed liquid crystal (nano-PDLC) material, which has higher light transmittance and faster response time, so that the transmitter can achieve higher efficiency and faster dynamic response when modulating light signals.

[0016] Preferably, the differential amplifier circuit in the transmitter uses a low-noise operational amplifier to reduce the noise generated by the amplifier when amplifying the sound signal, thereby improving the signal-to-noise ratio of the transmitted sound signal.

[0017] Preferably, the signal filtering circuit also includes a high-pass and low-pass filter circuit design for further limiting the frequency range of the transmitted sound signal to eliminate noise and interference within a specific frequency range and improve the clarity of the transmitted sound signal.

[0018] Preferably, the microphone / audio dual-channel input design further includes a closed-loop gain circuit for automatically adjusting the gain of the amplifier according to the strength of the input sound signal to avoid overload or distortion of the sound signal during amplification.

[0019] Preferably, encoding and decoding technology is also used for signal transmission between the transmitter and the receiver to improve the reliability and security of the transmission. The encoding technology is used to convert the sound signal into a specific coding sequence at the transmitter end, and the decoding technology is used to restore the received coding sequence to the original sound signal at the receiver end.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention modulates the sound signal through a liquid crystal shutter and uses a solar cell panel to directly detect the light signal, which significantly simplifies the structure of the photoelectric transmission and receiving equipment and reduces the manufacturing cost and maintenance difficulty; the design is intuitive and easy to understand, and users can easily operate it without having complex professional skills and knowledge, which greatly improves the convenience and popularity of use; through the design of signal filtering circuits and differential amplifier circuits, unnecessary frequency components are effectively filtered out and the signal amplification effect is enhanced, thereby ensuring the clarity and quality of the transmitted sound signal.

[0022] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a block diagram of the photoelectric transmitter of the present invention;

[0024] Figure 2 is a block diagram of a receiver of the present invention;

[0025] Figure 3 is a schematic diagram of a differential amplifier of the present invention;

[0026] Figure 4 A schematic diagram of a microphone / audio dual-channel input design of the present invention;

[0027] Figure 5 It is a schematic diagram of an inverting amplifier of the present invention;

[0028] Figure 6 This is a schematic diagram of the LM386 principle diagram of the present invention;

[0029] Figure 7 This is a schematic diagram of the LM386 gain switch diagram of the present invention;

[0030] Figure 8 It is a schematic diagram of the LM386 with bass boost function of the present invention;

[0031] Fig. 9 It is a schematic diagram of the application curve of LM386 with bass enhancement circuit of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this technical field without creative work are within the scope of protection of the present invention.

[0033] Example 1: Please refer to Figure 1 , Figure 2 The present invention provides a signal transmission method for a photoelectric transmitter based on a liquid crystal shutter, which simulates the principle of photoelectric signal transmission with a simple structure, making it easier to understand the voice feedback mode of photoelectric transmission.

[0034] 1. System model

[0035] (1) Photoelectric transmitter

[0036] Design a photoelectric transmitter based on the electro-optical effect of liquid crystal. The transmitter uses a liquid crystal shutter to modulate the sound signal. The amount of light passing through the device is modulated by controlling the voltage applied to the liquid crystal shutter, thereby realizing the wireless transmission of the sound signal.

[0037] Liquid crystal shutter is a controllable shutter glass that is made of liquid crystal material sandwiched between two layers of specially surface treated materials, which are called alignment layers. These layers are usually made of polymer materials that can align the liquid crystal molecules in a specific direction, parallel to the surface;

[0038] By using intensity modulation IM control to change the intensity of the light signal and control the voltage applied to the liquid crystal shutter, the amount of light passing through the device can be modulated. When the voltage increases, the rotation amplitude of the liquid crystal molecules is the largest, resulting in a significant change in the refractive index. The liquid crystal shutter will block or absorb more light, resulting in reduced transmittance or opacity. On the contrary, when the voltage is reduced or no voltage is applied, the liquid crystal molecules remain aligned, allowing more light to pass through, thereby increasing transmittance and transparency. Therefore, the liquid crystal shutter uses the electro-optical effect of liquid crystal. The light source illuminates the liquid crystal shutter and controls the transmission of light by manipulating the orientation of the liquid crystal molecules through an external voltage.

[0039] The liquid crystal shutter is made of nano-scale polymer dispersed liquid crystal material, which has higher light transmittance and faster response time, allowing the transmitter to achieve higher efficiency and faster dynamic response when modulating light signals;

[0040] (2) Receiver

[0041] Design a receiver for detecting changes in light intensity emitted by a photoelectric transmitter, which uses a solar panel to directly detect the light signal and convert it into an electrical signal;

[0042] Direct detection using solar panels, which are usually made of photovoltaic cells, used as light detectors to detect changes in light intensity from a light source passing through a liquid crystal shutter;

[0043] The light intensity variation signal received by the solar panel is demodulated into a speech signal, and the demodulated speech signal is post-processed by the receiving circuit and filtered and amplified to a certain degree, so that the speech signal is fed to the connected speaker to reconstruct the speech feedback.

[0044] The modulated optical signal is transmitted wirelessly via visible light (such as the light emitted by a flashlight). By controlling the intensity and direction of the transmitter's optical signal and the direction and position of the receiver, the transmission distance between the transmitter and the receiver and the receiver's sensitivity to the optical signal can be met.

[0045] 2. Circuit design

[0046] Both the transmitter and the receiver are equipped with corresponding circuit designs, including transmitter amplification design, signal filtering circuit, microphone / audio dual-path input design, and receiver preamplifier and audio amplifier design.

[0047] 1) Transmitter amplifier design, such as Figure 3 Shown

[0048] (1) Amplifier circuit, using the superposition principle, V1 is the AC input (microphone), V2 is the DC input (power supply), and the total output of the operational amplifier is V out(1) and V out(2) The sum of , therefore, the AC and DC output terms are:

[0049] AC output:

[0050] DC output:

[0051] Considering V out(1) and V out(2) , the total output of the operational amplifier is:

[0052]

[0053] Since the LCD shutter is driven by a signal between 0-5 volts, 1-3 volts is its desired optimal operating range. Therefore, the 1.5V DC output is set to an AC output with a peak-to-peak value of at least 1.0V. Based on these specifications, the closed-loop gain of the AC input is designed to be 40dB for the microphone path and 6.02dB for the audio jack input, respectively. The DC input voltage potential divider is 1, which sets it to a 1.5V DC offset when 3 volts are provided;

[0054]

[0055] Post-processing of the converted electrical signal, including amplification and filtering, to reconstruct the transmitted sound signal;

[0056] The differential amplifier circuit is used for processing and amplifying the input sound signal, and adopts a low-noise operational amplifier to reduce the noise generated by the amplifier when amplifying the sound signal, thereby improving the signal-to-noise ratio of the transmitted sound signal.

[0057] (2) Signal filtering circuit: Since the main sound frequency is from 100Hz to 3kHz.

[0058] C0 (in series with R1) acts as a high pass filter, blocking microphone DC current from entering the amplifier and cutting off frequencies below 100Hz.

[0059] When the frequency is 100Hz, the impedance of the capacitor is:

[0060]

[0061] C1 is like a low-pass filter, which can pass the amplified voice signal to the output end and filter out frequencies above 3kHz to eliminate unnecessary sound signals.

[0062]

[0063] The signal filtering circuit is used to filter out unnecessary frequency components to ensure the clarity and quality of the transmitted sound signal. C0 and C1 are used to further limit the frequency range of the transmitted sound signal to eliminate noise and interference within a specific frequency range and improve the clarity of the transmitted sound signal.

[0064] 2) Microphone / audio dual input design, such as Figure 4 Shown

[0065] (1) Path 1 (microphone input): In this case, the microphone can exhibit certain characteristics similar to a current source by simply converting sound waves (acoustic energy) into electrical signals (analog voltage or current). The output impedance of R1 is 2.2k2, which can passively convert the current signal into a voltage and then feed it into the post-amplification circuit.

[0066] (2) Path 2 (audio input): The audio input comes from the 3.5 mm audio jack of a computer or mobile phone. The output is a voltage signal that can be directly input into the next stage for amplification. Its peak-to-peak value is at least 1.0 V.

[0067] 3) Receiver preamplifier design, such as Figure 5 Shown

[0068] (1) Receiver inverting amplifier circuit: Figure 5 The inverting amplifier shown implements variable gain, and its gain equation is:

[0069]

[0070] By taking its logarithm, the variable gain can be controlled within [0dB, 20dB] to amplify the received weak signal to increase the signal strength.

[0071] 4) Receiver audio amplifier design, such as Figure 6 Shown

[0072] (1) Choose an LM386 integrated amplifier with a gain control circuit. The internal gain is set to 20, but adding an external resistor and capacitor between pins 1 and 8 can increase the gain to any value between 50 and 100.

[0073] like Figure 7 As shown, slide switch 1 (switch1) is used to select path 1 and path 2, but is connected in series with a 10uF capacitor C1.

[0074] (2) Select LM386 with low-pass filter circuit. By using a first-order passive low-pass filter f-3dB = 19.4kHz, the specific formula is:

[0075]

[0076] (3) Choose LM386 with bass enhancement circuit, such as Figure 8 As shown in Figure 1, bass enhancement is typically used to enhance sound signals between 100-300Hz. Additional external components are connected in parallel with the internal feedback resistor to adjust the gain and frequency response for bass enhancement applications. Fig. 9 As shown, the speaker with poor bass response has been compensated, with the typical boost peak occurring at a frequency of about 100 Hz.

[0077] The gain control circuit, low-pass filter circuit and bass enhancement circuit are used to adjust the volume, sound quality and bass effect of the output sound.

[0078] 3. Conclusion

[0079] By using a liquid crystal shutter to modulate the sound signal and transmit the sound signal through visible light (specifically a flashlight), a cutoff frequency of f was successfully achieved. tx =3288.3Hz photoelectric transmitter; the demodulated signal is driven by direct detection and post-processing (amplification and filtering) of the solar panel to drive the speaker, and then the sound signal sent back is reconstructed, achieving a cutoff frequency of f rx =19.4kHz photoelectric receiver.

[0080] Embodiment 2:

[0081] On the basis of Example 1, encoding and decoding technology is also used between the transmitter and the receiver in this embodiment for signal transmission to improve the reliability and security of transmission. The encoding technology is used to convert the sound signal into a specific coding sequence at the transmitter end, and the decoding technology is used to restore the received coding sequence to the original sound signal at the receiver end.

[0082] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A signal transmission method for a photoelectric transmitter based on a liquid crystal shutter, characterized in that: Design a photoelectric transmitter based on the electro-optical effect of liquid crystal. The transmitter uses a liquid crystal shutter to modulate the sound signal. The amount of light passing through the device is modulated by controlling the voltage applied to the liquid crystal shutter, thereby realizing the wireless transmission of the sound signal. Design a receiver for detecting changes in light intensity emitted by a photoelectric transmitter, which uses a solar panel to directly detect the light signal and convert it into an electrical signal; Post-processing of the converted electrical signal, including amplification and filtering, to reconstruct the transmitted sound signal; Both the transmitter and receiver are equipped with corresponding circuit designs, including transmitter amplification design, signal filtering circuit, microphone / audio dual-channel input design, and receiver preamplifier and audio amplifier design; The transmitter amplification design includes a differential amplifier circuit to process and amplify the incoming sound signal; The signal filtering circuit is designed to filter out unwanted frequency components to ensure the clarity and quality of the transmitted sound signal; The microphone / audio dual input design allows users to input sound signals through a microphone or audio jack; The receiver preamplifier design uses an inverting amplifier circuit to achieve variable gain, amplifying the received weak signal to increase the signal strength; The receiver audio amplifier design includes a gain control circuit, a low-pass filter circuit, and a bass enhancement circuit to adjust the volume, sound quality, and bass effect of the output sound; The modulated optical signal is transmitted wirelessly via visible light (such as the light emitted by a flashlight). By controlling the intensity and direction of the transmitter's optical signal and the direction and position of the receiver, the transmission distance between the transmitter and the receiver and the receiver's sensitivity to the optical signal can be met.

2. The signal transmission method of a photoelectric transmitter based on a liquid crystal shutter according to claim 1, characterized in that: The liquid crystal shutter is made of nano-scale polymer dispersed liquid crystal (nano-PDLC) material, which has higher light transmittance and faster response time, so that the transmitter can achieve higher efficiency and faster dynamic response when modulating light signals.

3. The signal transmission method of a photoelectric transmitter based on a liquid crystal shutter according to claim 1, characterized in that: The differential amplifier circuit in the transmitter adopts a low-noise operational amplifier to reduce the noise generated by the amplifier when amplifying the sound signal, thereby improving the signal-to-noise ratio of the transmitted sound signal.

4. The signal transmission method of a photoelectric transmitter based on a liquid crystal shutter according to claim 1, characterized in that: The signal filtering circuit also includes a high-pass and low-pass filter circuit design, which is used to further limit the frequency range of the transmitted sound signal to eliminate noise and interference within a specific frequency range and improve the clarity of the transmitted sound signal.

5. The signal transmission method of a photoelectric transmitter based on a liquid crystal shutter according to claim 1, characterized in that: The microphone / audio dual-channel input design also includes a closed-loop gain circuit for automatically adjusting the gain of the amplifier according to the strength of the input sound signal to avoid overload or distortion of the sound signal during the amplification process.

6. The signal transmission method of a photoelectric transmitter based on a liquid crystal shutter according to claim 1, characterized in that: Coding and decoding technology is also used for signal transmission between the transmitter and the receiver to improve the reliability and security of transmission. The coding technology is used to convert the sound signal into a specific coding sequence at the transmitter end, and the decoding technology is used to restore the received coding sequence to the original sound signal at the receiver end.

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