Interference pulse processing device of infrared remote control receiving chip

Abstract

The utility model discloses an interference pulse processing device of an infrared remote control receiving chip, which comprises a pre-processing circuit and an infrared receiving chip, the right end of the pre-processing circuit is connected with an integrating circuit, the right end of the integrating circuit is connected with a Schmidt trigger circuit, and the Schmidt trigger circuit is connected with a monostable trigger control circuit below. The right end of the Schmidt trigger circuit is connected with the output circuit, the pre-processing circuit converts infrared signals into electric signals and amplifies and filters the electric signals, unnecessary integral charging and unnecessary change of AGC parameters are improved, the recognition capability of the infrared signals is improved, the Schmidt trigger circuit generates switching control signals SCS, and the switching control signals SCS are connected with the output circuit. Meanwhile, SCS signals output by Schmidt trigger shaping are output to the monostable trigger circuit, the integral circuit and the AGC control circuit are controlled during the period of generating monostable trigger control signals, the repeated charging phenomenon is restrained, the AGC state is changed unnecessarily, and the recognition capacity of infrared signals is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field related to infrared remote control receiving chips, and particularly relates to an interference pulse processing device for an infrared remote control receiving chip. Background Art

[0002] An infrared remote control receiving chip converts an infrared light encoded signal into an electrical encoded signal, amplifies and filters the converted electrical encoded signal, and serves as a preprocessing circuit for encoded pulse signals. The specific implementation process includes photoelectric conversion, pre-amplification, charge and discharge actions on pulse signals, demodulation of modulation signals, processing of modulated signals with a Schmitt trigger circuit to provide a switch control signal, shaping the switch signal, and outputting the final output signal to an external output circuit.

[0003] However, with the development of CMOS process technology and the improvement of integration for infrared receiving chips, the circuit area is continuously reduced. Therefore, the input and output layouts may be very close. When the output signal changes from low level to high level, due to the coupling phenomenon of the internal capacitance and resistance of the semiconductor substrate when the output signal changes, or the package may have the output and the photodiode very close, the high-frequency noise of the rapidly changing output signal can be coupled from the output end to the input end. Especially when the signal at the output end is very large and the rising period of the pulse signal changes rapidly, a lot of high-frequency harmonics will be generated directly interfering with the input end. Once the controlled AGC gain is very large or the signal is very large, it is easily interfered. Due to the above interference situations, the infrared receiving chips in traditional technologies may have two situations that affect normal reception. First, in the integrator, noise is generated due to the change of the output pulse, and unwanted noise will be recharged. Because of the distributed noise of the output signal and the influence of charging, the charging parameters change, resulting in an output signal with a pulse width wider than the output pulse of the emitted infrared signal. When the noise is large, a multi-pulse phenomenon will occur, directly outputting an interfering signal. Second, if only the above two phenomena are processed in the integration circuit, it is not enough. Since these interferences will also change the control parameters of the AGC, if this phenomenon accumulates continuously in a sequence of pulses, the AGC change will also be interfered, and the gain decrease will accelerate. As a result, the parsing of these sequence codes will be incomplete or the pulse width will become narrower, and even codes will be lost at the back end of the sequence code. When the sequence code is transmitted to the MCU, it will cause misoperation of the electronic device or inability to recognize the operation command. Summary of the Utility Model

[0004] The purpose of the present utility model is to provide an interference pulse processing device for an infrared remote control receiving chip, so as to solve the problem of an infrared receiving chip proposed in the above background technology, improve unnecessary integral charging and unnecessary change of AGC parameters, improve the recognition ability of infrared signals, and at the same time output the SCS signal output by the Schmitt trigger shaping to the monostable trigger circuit, control the integral circuit and the AGC control circuit during the generation of the monostable trigger control signal, suppress the repeated charging phenomenon and unnecessary change of the AGC state, and improve the recognition ability of infrared signals.

[0005] To achieve the above object, the present utility model provides the following technical solution: The preprocessing circuit 1 includes an input circuit 4, the right end of the input circuit 4 is connected to a preamplifier 5, the right end of the preamplifier 5 is connected to a VGA amplifier 6, the right end of the VGA amplifier 6 is connected to a limiting amplifier 7, the right end of the limiting amplifier 7 is connected to a band-pass filter 8, the bottom of the band-pass filter 8 is connected to a gain adjustment circuit 9, and the right end of the band-pass filter 8 is connected to a comparator 10. The gain adjustment circuit 9 includes a control circuit 16, and the right end of the control circuit 16 is connected to a signal detector 17.

[0006] Compared with the prior art, the present utility model provides an interference pulse processing device for an infrared remote control receiving chip, which has the following beneficial effects:

[0007] 1. Through the settings of the input circuit, preamplifier, VGA amplifier, limiter amplifier, band-pass filter, gain adjustment circuit, comparator, control circuit, and signal detection, the preprocessing circuit converts the infrared signal into an electrical signal, amplifies and filters the electrical signal, and provides the pulse signal PS of the pulse sequence to the integration circuit by comparing the filtered signal with the reference voltage. First, the input circuit detects the infrared signal input from the outside and converts the infrared signal into an electrical signal. Usually, the input circuit includes a photodiode. The preamplifier amplifies the very small electrical signal of the input circuit to a certain value and provides the amplified signal to the automatic gain control amplifier. The automatic gain control amplifier adjusts the gain of the amplified signal and provides a signal with adjustable gain to the limiter. For example, the larger the gain adjustment current or gain adjustment voltage of the automatic gain control amplifier, the smaller the gain of the receiver. The limiter amplifier amplifies the signal with excessive gain adjustment again and provides the amplified signal to the band-pass filter. The band-pass filter filters out other frequency signals in the infrared signal from the amplified signal of the limiter amplifier and retains only the carrier frequency signal to provide to the gain adjustment circuit and the comparator. The gain adjustment circuit automatically adjusts the gain of the amplifier or maintains the original gain according to the magnitude of the only carrier frequency signal, generating a gain adjustment current voltage or keeping the gain unchanged. The comparator compares the only carrier frequency signal with the reference voltage Vref1 and provides the pulse signal PS of the carrier frequency pulse sequence to the integration circuit according to the comparison result. The integration circuit completes the charge and discharge actions of the carrier frequency pulse signal PS, filters out the carrier, and provides the demodulation signal DS of the charge and discharge action to the Schmitt trigger circuit. For example, the charge and discharge control signal of the integration circuit is the reference voltage Vref2. If it is lower than this reference voltage, the internal capacitor is charged. If the charge and discharge control signal is higher than the reference voltage Vref1, the internal capacitor is discharged. The Schmitt trigger circuit completes the work of the Schmitt trigger circuit according to the first and second threshold voltages on the demodulation signal DS, generates the switch control signal SCS, and provides the switch control signal SCS to the output circuit and the monostable trigger control circuit. The Schmitt trigger circuit converts the switch control signal SCS using its hysteresis characteristic. For example, when the Schmitt trigger circuit generates the switch control signal SCS, if the demodulation signal DS is higher than the first threshold voltage Vt1, it is at a low level. If the demodulation signal DS is lower than the second threshold voltage Vt2, it is at a high level. The output circuit responds to the switch control signal SCS to complete the switch operation and outputs the final output signal OUT in the form of a pulse to the external MCU according to the switch action. The monostable trigger control circuit receives the switch control signal SCS and performs a monostable trigger operation on the switch control signal SCS, generating the control signal CS through discharge and NAND logic operations and controlling the integration circuit and the gain adjustment circuit. Among them, the control signal CS can be used to adjust the demodulation signal DS output from the integration circuit to be at a low level during its control signal period, and at the same time control the gain adjustment circuit to keep Vcount unchanged during the effective time of the monostable trigger circuit CS, so that the gain also remains unchanged.

[0008] 2. Through the settings of the monostable trigger control circuit, inverter, and output logic NAND circuit, for the reference voltage Vnode at the connection point of the charge and discharge resistor R and the charge and discharge capacitor, when the SCS output is at a low level, the CS output of the monostable trigger circuit is at a high level. After long-term charging, the reference voltage Vnode is at a high level. When the SCS changes from a low level to a high level, the NAND gate output CS is at a low level. At this time, the inverter output is at a low level, and the capacitor C discharges through the resistor inverter until the reference level is lower than the control level of the NAND gate, and then the NAND gate output CS returns to a high level. The duration of the negative pulse maintained by the monostable output depends on the discharge time of R and C. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic structural diagram of the present invention.

[0010] Figure 2 It is a time control circuit diagram of the monostable trigger in the present invention.

[0011] Figure 3 It is a working timing diagram of the infrared receiving chip in the present invention.

[0012] In the figure: 1. Preprocessing circuit; 2. Monostable trigger control; 3. Infrared receiving chip; 4. Input circuit; 5. Preamplifier; 6. VGA amplifier; 7. Limiting amplifier; 8. Band-pass filter; 9. Gain adjustment circuit; 10. Comparator; 11. Integrating circuit; 12. Schmitt trigger circuit; 13. Output circuit; 14. Inverter; 15. Output logic NAND circuit; 16. Control circuit; 17. Signal detection. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0014] The present invention provides an interference pulse processing device for an infrared remote control receiving chip as shown in Figures 1-3 which includes a preprocessing circuit 1 and an infrared receiving chip 3;

[0015] The right end of the preprocessing circuit 1 is connected to an integrating circuit 11. The right end of the integrating circuit 11 is connected to a Schmitt trigger circuit 12. The Schmitt trigger circuit 12 is connected to the monostable trigger control circuit 2 below, and the right end of the Schmitt trigger circuit 12 is connected to the output circuit 13;

[0016] The pre - processing circuit 1 includes an input circuit 4. The right end of the input circuit 4 is connected to a pre - amplifier 5. The right end of the pre - amplifier 5 is connected to a VGA amplifier 6. The right end of the VGA amplifier 6 is connected to a limiting amplifier 7. The right end of the limiting amplifier 7 is connected to a band - pass filter 8. The bottom of the band - pass filter 8 is connected to a gain - adjustment circuit 9. The right end of the band - pass filter 8 is connected to a comparator 10.

[0017] The gain - adjustment circuit 9 includes a control circuit 16. The right end of the control circuit 16 is connected to a signal detector 17.

[0018] The monostable trigger control circuit 2 internally includes an inverter 14. The right end of the inverter 14 is connected to an output logic NAND circuit 15. A charge - discharge resistor and a charge - discharge capacitor are arranged at the middle position between the inverter 14 and the output logic NAND circuit 15.

[0019] The band - pass filter 8 filters out the electrical signal V(f0) other than the unique carrier from the amplified signal. The band - pass filter 8 provides the unique carrier signal to the comparator 10. The comparator 10 compares the filtered signal with the reference voltage Vref1 and provides a pulse - sequence signal PS to the integration circuit 11 according to the comparison result. The integration circuit 11 can provide a demodulation signal DS based on the charge - discharge action to the Schmitt trigger circuit 12. The Schmitt trigger circuit 12 generates a switch control signal SCS.

[0020] In this embodiment, for the specific implementation steps of the interference - pulse processing device of an infrared remote - control receiving chip, a demodulation coding signal is generated according to the high - and low - level signals, shaped, and finally output to the external output circuit. At the same time, the above - mentioned Schmitt trigger circuit generates a switch control signal SCS. The switch control signal SCS is input to the monostable trigger control circuit 2. The monostable trigger control circuit 2 will output a control signal to control the integration circuit 11 and the gain - adjustment circuit 9, and keep the output of the integration circuit at a low level during the effective time of the monostable trigger control circuit. At the same time, within the effective time of the monostable trigger control circuit 2, the gain - adjustment circuit 9 does not perform gain - adjustment processing and remains in its original state. The monostable trigger control circuit includes that the switch control signal SCS is connected to the input end of the inverter 14 and the input end of the logic NAND gate 15. The output end of the inverter 14 is connected to one end of a charge - discharge resistor R, and the other end is connected to a discharge capacitor. The connection point Vnode of the charge - discharge resistor and the capacitor is connected to the other input end of the logic NAND gate 15. Among them, the discharge level of the reference point Vnode performs a logic NAND operation with the SCS signal. The output of the logic NAND gate controls the integration circuit and the AGC control circuit, and keeps the integration circuit at a low level during the generated control time, so that the gain controlled by the AGC remains unchanged.

[0021] As Figure 1 and Figure 3As shown, the preprocessing circuit 1 includes an input circuit 4. The right end of the input circuit 4 is connected to a preamplifier 5. The right end of the preamplifier 5 is connected to a VGA amplifier 6. The right end of the VGA amplifier 6 is connected to a limiting amplifier 7. The right end of the limiting amplifier 7 is connected to a band-pass filter 8. The bottom of the band-pass filter 8 is connected to a gain adjustment circuit 9. The right end of the band-pass filter 8 is connected to a comparator 10. The gain adjustment circuit 9 includes a control circuit 16, and the right end of the control circuit 16 is connected to a signal detector 17.

[0022] Preferably, the preprocessing circuit 1 converts the infrared signal into an electrical signal, amplifies and filters the electrical signal, and provides the pulse signal PS of the pulse sequence to the integrating circuit 11 by comparing the filtered signal with the reference voltage. First, the input circuit 4 detects the infrared signal input from the outside and converts the infrared signal into an electrical signal. Usually, the input circuit 4 includes a photodiode. The preamplifier 5 amplifies the very small electrical signal of the input circuit 4 to a certain value and provides the amplified signal to the automatic gain control amplifier 6. The automatic gain control amplifier 6 adjusts the gain of the amplified signal and provides a signal with adjustable gain to the limiter 7. For example, the larger the gain adjustment current or gain adjustment voltage of the automatic gain control amplifier 6, the smaller the gain of the receiver. The limiting amplifier 7 re-amplifies the signal with excessive gain adjustment and provides the amplified signal to the band-pass filter 8. The band-pass filter 8 filters out other frequency signals in the infrared signal from the amplified signal of the limiting amplifier 7 and retains only the carrier frequency signal to provide to the gain adjustment circuit 9 and the comparator 10. The gain adjustment circuit 9 automatically adjusts the gain of the amplifier 6 or maintains the original gain according to the magnitude of the only carrier frequency signal, generating a gain adjustment current voltage or unchanged gain. The comparator 10 compares the only carrier frequency signal with the reference voltage Vref1 and provides the pulse signal PS of the carrier frequency pulse sequence to the integrating circuit 11 according to the comparison result. The integrating circuit 11 completes the charge and discharge actions of the carrier frequency pulse signal PS, filters out the carrier, and provides the demodulation signal DS of the charge and discharge action to the Schmitt trigger circuit 12. For example, the charge and discharge control signal of the integrating circuit 11 is the reference voltage Vref2. If it is lower than this reference voltage, the internal capacitor is charged. If the charge and discharge control signal is higher than the reference voltage Vref2, the internal capacitor is discharged. The Schmitt trigger circuit 12 completes the work of the Schmitt trigger circuit according to the first and second threshold voltages on the demodulation signal DS, generates the switch control signal SCS, and provides the switch control signal SCS to the output circuit 13 and the monostable trigger control circuit 2. The Schmitt trigger circuit 12 converts the switch control signal SCS using its hysteresis characteristic. For example, the Schmitt trigger circuit 12 generates the switch control signal SCS. If the demodulation signal DS is higher than the first threshold voltage Vt1, it is at a low level. If the demodulation signal DS is lower than the second threshold voltage Vt2, it is at a high level. The output circuit 13 responds to the switch control signal SCS to complete the switch operation and outputs the final output signal OUT in the form of a pulse to the external MCU according to the switch action. The monostable trigger control circuit 2 receives the switch control signal SCS and performs a monostable trigger operation on the switch control signal SCS, generating the control signal CS through discharge and NAND logic operations and controlling the integrating circuit 11 and the gain adjustment circuit 9. Among them, the control signal CS can be used to adjust the demodulation signal DS output from the integrating circuit 11 to be at a low level during its control signal period, and at the same time control the gain adjustment circuit to keep Vcount unchanged during the effective time of the monostable trigger circuit CS, so that the gain remains unchanged.

[0023] As Figure 2 shown, the monostable trigger control circuit 2 internally includes an inverter 14, the right end of the inverter 14 is connected to an output logic NAND circuit 15, and a charge-discharge resistor and a charge-discharge capacitor are arranged at the middle position between the inverter 14 and the output logic NAND circuit 15.

[0024] Preferably, for the reference voltage Vnode at the connection point of the charge-discharge resistor R and the charge-discharge capacitor, when the SCS output is at a low level, the monostable trigger circuit output CS is at a high level. After long-term charging, the reference voltage Vnode is at a high level. When SCS changes from a low level to a high level, the NAND gate output CS is at a low level. At this time, the inverter output is at a low level, and the capacitor C discharges through the resistor inverter until the reference level is lower than the NAND gate control level, and then the NAND gate output CS returns to a high level. The time to maintain the monostable output negative pulse depends on the discharge time of R and C. Generally, Tw = 1.2RxC.

[0025] As Figure 3 shown, the band-pass filter 8 filters out the electrical signal V(f0) other than the only carrier from the amplified signal. The band-pass filter 8 provides the only carrier signal to the comparator 10. The comparator 10 compares the filtered signal with the reference voltage Vref1 and provides a pulse sequence signal PS to the integrator 11 according to the comparison result. The integrator 11 can provide a demodulation signal DS according to the charge-discharge action to the Schmitt trigger circuit 12, and the Schmitt trigger circuit 12 generates a switch control signal SCS.

[0026] Optionally, the infrared receiving chip 3 can adjust the internal signal of the integrator during the integrator discharge action, so that the output of the integrator remains at a low level for a period of time. In addition, by keeping the output of the integrator at a low level for a period of time, the infrared receiving chip 3 can suppress or reduce the mischarging operation caused by noise. The Schmitt trigger circuit 12 of the infrared receiving chip 3 will not have deviation or multiple pulses in the output pulse width due to noise, improving the receiving efficiency and correctness of the infrared receiving chip 3. To ensure that there is no error accumulation in the gain, Vcount is kept unchanged during the interference period, so that it will not affect the long code protocol.

[0027] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An interference pulse processing device for an infrared remote control receiving chip, comprising a preprocessing circuit (1) and an infrared receiving chip (3); The right end of the preprocessing circuit (1) is connected to an integrating circuit (11), the right end of the integrating circuit (11) is connected to a Schmidt trigger circuit (12), the Schmidt trigger circuit (12) is connected to the monostable trigger control circuit (2) below, and the right end of the Schmidt trigger circuit (12) is connected to an output circuit (13); It is characterized in that: The preprocessing circuit (1) includes an input circuit (4), the right end of the input circuit (4) is connected to a preamplifier (5), the right end of the preamplifier (5) is connected to a VGA amplifier (6), the right end of the VGA amplifier (6) is connected to a limiting amplifier (7), the right end of the limiting amplifier (7) is connected to a band-pass filter (8), the bottom of the band-pass filter (8) is communicated with a gain adjustment circuit (9), and the right end of the band-pass filter (8) is connected to a comparator (10).

2. The interference pulse processing device of an infrared remote control receiving chip according to claim 1, wherein: The gain adjustment circuit (9) includes a control circuit (16), and the right end of the control circuit (16) is connected to a signal detector (17).

3. The interference pulse processing device of an infrared remote control receiving chip according to claim 1, wherein: The monostable trigger control circuit (2) internally includes an inverter (14), the right end of the inverter (14) is connected to an output logic NAND circuit (15), and a charge-discharge resistor and a charge-discharge capacitor are arranged at the middle position between the inverter (14) and the output logic NAND circuit (15).

4. The interference pulse processing device for an infrared remote control receiving chip according to claim 1, wherein: The band-pass filter (8) filters out the electrical signal V(f0) other than the only carrier wave from the amplified signal, the band-pass filter (8) provides the only carrier wave signal to the comparator (10), the comparator (10) compares the filtered signal with the reference voltage Vref1, and provides a pulse sequence signal PS to the integrating circuit (11) according to the comparison result. The integrating circuit (11) can provide a demodulation signal DS according to the charge-discharge action to the Schmidt trigger circuit (12), and the Schmidt trigger circuit (12) generates a switch control signal SCS.

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