Abnormality detection circuit based on differential signal

Abstract

The utility model discloses an anomaly detection circuit based on differential signals, and relates to the technical field of printers. According to the digital ink-jet printer, the master control MCU, the differential IC and the comparator LM339 module are integrated, so that external and communication interface signals are accurately monitored, a single-end signal is converted into a differential signal by the circuit, the anti-interference capability is enhanced, and the signal accuracy is ensured through the processing of the comparator; machine faults caused by poor contact or software defects are effectively prevented, the risks of error reporting and board card burning are reduced, the maintenance process is simplified, the cost is reduced, meanwhile, hardware problems can be found in time, the service life of equipment is prolonged, and the user experience is optimized.

Description

TECHNICAL FIELD

[0001] The utility model relates to printer technical field especially based on the abnormal detection circuit of difference signal. BACKGROUND

[0002] In the field of digital inkjet printer, especially for improving the reliability of the printer and reducing the failure caused by external connection problem or software control defect, in the existing printer design, although the peripheral interface and communication interface are universal, but often because of the poor contact of external connecting device or the unreasonable software control logic, the machine works abnormally, such as frequent error or even burning internal board card, these problems not only affect the stability and service life of the printer, but also increase the maintenance cost and the operation difficulty of the user. SUMMARY

[0003] The utility model discloses in order to solve the technical problem existing above, provide a kind of based on the abnormal detection circuit of difference signal.

[0004] The technical scheme of the utility model is realized as follows:

[0005] A kind of based on the abnormal detection circuit of difference signal, including main control MCU module, difference IC module, comparator LM339 module,

[0006] The main control MCU module outputs signal by TXD1 and TXD2 pin, for transmission to difference IC module, in difference IC module, the input signal is converted into difference form TXD1+, TXD1-, TXD2+ and TXD2- signal, then be sent to comparator LM339 module, in LM339 module, difference signal is further processed and compared, and processing result is fed back to main control MCU module by CHECK_TXD1+, CHECK_TXD1-, CHECK_TXD2+ and CHECK_TXD2- pin;

[0007] The main control MCU module is used for executing program instruction, processing input and output signal and managing the running state of system, drives difference IC module by sending control signal, carries out the differential transmission of signal, and the main control MCU module is also used for receiving the feedback signal of comparator LM339 module;

[0008] The difference IC module is used for converting the single-ended signal output by main control MCU module into difference signal, for the conditioning and protection of circuit;

[0009] The comparator LM339 module is used for comparing and processing the differential signals output by the differential IC module, converting the differential signals into single-ended signals, wherein the comparison result is used for triggering an alarm and adjusting system parameters, and the comparator LM339 module is also used for feeding back the comparison result to the master MCU module.

[0010] Further, the master MCU module comprises a REFC, one end of the REFC is connected to the resistor R932 and the resistor R933, the other end of the resistor R932 is connected to 3V3 MCU, and the other end of the resistor R932 is connected to the ground.

[0011] Further, the differential IC module comprises a chip U2, the first pin of the chip U2 is connected to TXD1, the seventh pin of the chip U2 is connected to TXD2, the fourth pin and the twelfth pin of the chip U2 are both connected to the ground, the second pin of the chip U2 is connected to the fifth pin of the resistor network, the third pin of the chip U2 is connected to the sixth pin of the resistor network, the fifth pin of the chip U2 is connected to the seventh pin of the resistor network, and the sixth pin of the chip U2 is connected to the eighth pin of the resistor network.

[0012] Further, the fourth pin of the resistor network is connected to one end of the capacitor C562 and the second pin of the resistor network, the third pin of the resistor network is connected to one end of the capacitor C561 and the sixth pin of the chip BLN3, the second pin of the resistor network is connected to one end of the capacitor C562 and the seventh pin of the chip BLN3, the first pin of the resistor network is connected to the other end of the capacitor C562 and the eighth pin of the chip BLN3, the other end of the capacitor C561 is connected to one end of the capacitor C562 and the fifth pin of the chip BLN3, the fourth pin of the chip BLN3 is connected to TXD1+, the third pin of the chip BLN3 is connected to TXD1-, the second pin of the chip BLN3 is connected to TXD2-, and the first pin of the chip BLN3 is connected to TXD2+.

[0013] Further, the comparator LM339 module comprises a comparator U1, the ninth pin of the comparator U1 is connected to the ground through the resistor R940, one end of the resistor is also connected to the ground through the diode D158,

[0014] One end of the diode is connected to TXD1+ through resistor R938. Pin 8 of comparator U1 is connected at the junction of resistors R946 and R947. One end of resistor R947 is also connected to ground. Pin 12 of comparator U1 is connected to ground. Pin 3 of comparator U1 is connected at the junction of 3V3_MCU and one end of resistor R941. One end of 3V3_MCU is also connected to ground through capacitor C571. Pin 14 of comparator U1 is connected at the junction of one end of resistor R944 and the other end of resistor R941. The other end of resistor R944 is connected to ground through capacitor C572. The other end of resistor R944 is also connected to CHECK_TXD1+.

[0015] Furthermore, pin 5 of comparator U1 is connected to ground via resistor R942. One end of the resistor is also connected to ground via diode D159. One end of the diode is connected to TXD1- via resistor R939. Pin 3 of comparator U1 is connected at the junction of 3V3_MCU and one end of resistor R943. Pin 2 of comparator U1 is connected at the junction of one end of resistor R945 and the other end of resistor R943. The other end of resistor R945 is connected to ground via capacitor C573. The other end of resistor R945 is also connected to CHECK_TXD1-.

[0016] Furthermore, 3V3_MCU is the logic power supply; TXD1 and TXD2 are the main control's transmit output signals; TXD1+ and TXD1- are the differential pair output signals of signal TXD1; TXD2+ and TXD2- are the differential pair output signals of signal TXD2; REFC is the reference voltage; comparator U1 is an LM339 comparator; chip U2 is a differential IC: CHECK_TXD1+, CHECK_TXD1-, CHECK_TXD1+, and CHECK_TXD2- are the four digital signals output by the comparator.

[0017] Beneficial effects:

[0018] This invention significantly improves the reliability and stability of digital inkjet printers. Through the coordinated work of the main control MCU module, differential IC module, and comparator LM339 module, it achieves precise monitoring and processing of printer peripheral interface and communication interface signals. Specifically, the main control MCU module is responsible for outputting signals and receiving feedback, the differential IC module converts single-ended signals into differential signals to enhance anti-interference capability, and the comparator LM339 module compares and processes these differential signals to ensure the accuracy and integrity of the signals.

[0019] This invention effectively detects and diagnoses signal anomalies that printers may encounter during startup or operation, such as poor contact of external connecting devices or unreasonable software control logic. This not only reduces machine malfunctions, such as frequent errors or burnt-out internal circuit boards, but also lowers maintenance costs and reduces the difficulty of operation for users. In addition, it helps to promptly detect and resolve hardware circuit malfunctions or damage, thereby extending the printer's lifespan and improving the user's operating experience. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the system block structure of this utility model;

[0021] Figure 2 This is the circuit design diagram of the main control MCU module of this utility model;

[0022] Figure 3 This is a differential IC module of the present invention;

[0023] Figure 4 This utility model relates to the comparator LM339 module. Detailed Implementation

[0024] like Figures 1-2 As shown, this utility model discloses an anomaly detection circuit based on differential signals, including a main control MCU module, a differential IC module, and a comparator LM339 module.

[0025] The main control MCU module outputs signals through the TXD1 and TXD2 pins. These signals are transmitted to the differential IC module. In the differential IC module, the input signals are converted into differential TXD1+, TXD1-, TXD2+, and TXD2- signals. These differential signals are then sent to the comparator LM339 module. In the LM339 module, the differential signals are further processed and compared. The processing result is fed back to the main control MCU module through the CHECK_TXD1+, CHECK_TXD1-, CHECK_TXD2+, and CHECK_TXD2- pins, completing the closed-loop control of the entire signal processing flow. This connection method ensures accurate transmission and processing of signals between different modules, and also realizes the internal monitoring and feedback mechanism of the system.

[0026] The main control MCU module is used to execute program instructions, process input and output signals, and manage the system's operating status. It drives the differential IC module by sending control signals (TXD1 and TXD2) to achieve differential signal transmission. At the same time, the main control MCU is also used to receive feedback signals (CHECK_TXD1+, CHECK_TXD1-, CHECK_TXD2+, CHECK_TXD2-) from the comparator LM339 module to monitor the system's operating status and make necessary adjustments.

[0027] The main function of the differential IC module is to convert the single-ended signals (TXD1 and TXD2) output by the main control MCU module into differential signals (TXD1+, TXD1-, TXD2+, TXD2-). This conversion helps to reduce interference during signal transmission, improve the anti-interference capability and transmission quality of the signal. Differential signals have better performance in long-distance transmission and high-speed communication. Therefore, the differential IC module plays a role in signal conditioning and protection in the system.

[0028] The main function of the comparator LM339 module is to compare and process the differential signals output by the differential IC module, convert the differential signals (TXD1+, TXD1-, TXD2+, TXD2-) into single-ended signals, and output the comparison results. These comparison results can be used for subsequent processing such as triggering alarms and adjusting system parameters. At the same time, the LM339 module is also responsible for feeding back the comparison results to the main control MCU module (through the CHECK_TXD1+, CHECK_TXD1-, CHECK_TXD2+, CHECK_TXD2- pins) to realize closed-loop control and monitoring of the system.

[0029] Furthermore, the main control MCU module includes a REFC, which is connected to one end of resistors R932 and R933. The other end of resistor R932 is connected to 3V3_MCU and ground.

[0030] Furthermore, the differential IC module includes a chip U2, with pin 1 of chip U2 connected to TXD1, pin 7 of chip U2 connected to TXD2, pins 4 and 12 of chip U2 both connected to ground, pin 2 of chip U2 linked to pin 5 of the resistor network, pin 3 of chip U2 linked to pin 6 of the resistor network, pin 5 of chip U2 linked to pin 7 of the resistor network, and pin 6 of chip U2 linked to pin 8 of the resistor network.

[0031] Furthermore, pin 4 of the resistor network is connected to the junction of one end of capacitor C562 and pin 2 of the resistor network; pin 3 of the resistor network is connected to the junction of one end of capacitor C561 and pin 6 of chip BLN3; pin 2 of the resistor network is connected to the junction of one end of capacitor C562 and pin 7 of chip BLN3; pin 1 of the resistor network is connected to the junction of the other end of capacitor C562 and pin 8 of chip BLN3; the other end of capacitor C561 is connected to the junction of one end of capacitor C562 and pin 5 of chip BLN3; pin 4 of chip BLN3 is connected to TXD1+; pin 3 of chip BLN3 is connected to TXD1-; pin 2 of chip BLN3 is connected to TXD2-; and pin 1 of chip BLN3 is connected to TXD2+.

[0032] Furthermore, the comparator LM339 module includes comparator U1, whose 9th pin is connected to ground via resistor R940, and one end of the resistor is also connected to ground via diode D158.

[0033] One end of the diode is connected to TXD1+ through resistor R938. Pin 8 of comparator U1 is connected at the junction of resistors R946 and R947. One end of resistor R947 is also connected to ground. Pin 12 of comparator U1 is connected to ground. Pin 3 of comparator U1 is connected at the junction of 3V3_MCU and one end of resistor R941. One end of 3V3_MCU is also connected to ground through capacitor C571. Pin 14 of comparator U1 is connected at the junction of one end of resistor R944 and the other end of resistor R941. The other end of resistor R944 is connected to ground through capacitor C572. The other end of resistor R944 is also connected to CHECK_TXD1+.

[0034] Furthermore, pin 5 of comparator U1 is connected to ground via resistor R942. One end of the resistor is also connected to ground via diode D159. One end of the diode is connected to TXD1- via resistor R939. Pin 3 of comparator U1 is connected at the junction of 3V3_MCU and one end of resistor R943. Pin 2 of comparator U1 is connected at the junction of one end of resistor R945 and the other end of resistor R943. The other end of resistor R945 is connected to ground via capacitor C573. The other end of resistor R945 is also connected to CHECK_TXD1-.

[0035] Furthermore, 3V3_MCU is the logic power supply; TXD1 and TXD2 are the main control's transmit output signals; TXD1+ and TXD1- are the differential pair output signals of signal TXD1; TXD2+ and TXD2- are the differential pair output signals of signal TXD2; REFC is the reference voltage; comparator U1 is an LM339 comparator; chip U2 is a differential IC: CHECK_TXD1+, CHECK_TXD1-, CHECK_TXD1+, and CHECK_TXD2- are the four digital signals output by the comparator;

[0036] Working principle:

[0037] (1) When the TXD1 and TXD2 output signals of the main control MCU are “1”, if the external interface is in a floating state, then the voltage of TXD1+ and TXD2+ is 3.3V, and the voltage of TXD1- and TXD2- is 0V.

[0038] (2) When the TXD1 and TXD2 output signals of the main control MCU are “0”, if the external interface is in a floating state, then the voltage of TXD1+ and TXD2+ is 0V, and the voltage of TXD1- and TXD2- is 3.3V.

[0039] (3) When the TXD1 and TXD2 output signals of the main control MCU are "1", if the external interface is connected to the signal receiving interface, then the voltage of TXD1+ and TXD2+ is 2.4V, and the voltage of TXD1- and TXD2- is 0.8V.

[0040] (4) When the TXD1 and TXD2 output signals of the main control MCU are “0”, if the external interface is connected to the signal receiving interface, then the voltage of TXD1+ and TXD2+ is 0.8V, and the voltage of TXD1- and TXD2- is 2.4V.

[0041] (5) The voltage VREF of REFC = 1 / (1+2)*3.3V = 1.1V;

[0042] (6) When the external interface is in a floating state, and the voltage of TXD1+ and TXD2+ is 3.3V, since VREF = 1.1V, according to the comparator principle, the output voltage of CHECK_TXD1+ and CHECK_TXD2+ is high level 3.3V; when the voltage of TXD1- and TXD2- is 0V, since VREF = 1.1V, according to the comparator principle, the output voltage of CHECK_TXD1- and CHECK_TXD2- is high level 0V; at this time, the main control MCU judges whether it is reasonable based on the voltage status (1)(2)(3)(4) of the output signals TXD1 and TXD2 of CHECK_TXD1+, CHECK_TXD2+, CHECK_TXD1-, and CHECK_TXD2-. If it is reasonable, it means that the hardware circuit function is normal. If it is unreasonable, it means that the circuit function is abnormal and damaged.

[0043] (7) When the external interface is connected to the signal receiving interface, the voltage of TXD1+ and TXD2+ is 2.4V. Since VREF = 1.1V, according to the comparator principle, the output voltage of CHECK_TXD1+ and CHECK_TXD2+ is high level 3.3V. When the voltage of TXD1- and TXD2- is 0.8V, since VREF = 1.1V, according to the comparator principle, the output voltage of CHECK_TXD1- and CHECK_TXD2- is high level 0V. At this time, the MCU judges whether the voltage values ​​of CHECK_TXD1+, CHECK_TXD2+, CHECK_TXD1-, CHECK_TXD2- and the voltage status of the output signals TXD1 and TXD2 are reasonable based on (1)(2)(3)(4). If it is reasonable, it means that the hardware circuit function is normal. If it is unreasonable, it means that the circuit function is abnormal or damaged, or the ribbon cable is not properly connected, etc. The interface cannot communicate with the external differential receiving signal. At this time, the problem point needs to be checked.

[0044] If CHECK_TXD1+, CHECK_TXD2+, CHECK_TXD1-, and CHECK_TXD2- are detected, it indicates that the signal communication function is normal and the system can enter the normal working state mechanism. At this point, the detection mechanism is complete. If the above detection signals do not match, it indicates that the communication interface function is abnormal, the system reports an error, and the abnormal problem needs to be investigated.

[0045] The anomaly detection circuit of this invention outputs a signal from the main control MCU module to the differential IC module, converting the single-ended signal into a differential signal to improve anti-interference capability. These differential signals are then fed into the comparator LM339 module for processing and comparison. The comparator feeds back the processed signal to the main control MCU module, forming a closed-loop control system. This circuit can detect whether the initial state of communication signals and software control is normal. Through the feedback signal output by the comparator, the main control MCU can determine the system's operating status and make necessary adjustments. Furthermore, the circuit design includes a reference voltage circuit and detailed resistor and capacitor configurations to ensure accurate signal transmission and processing. In this way, this invention can accurately detect and diagnose whether the initial signal state of a digital inkjet printer is normal, thereby preventing machine errors or board damage caused by signal anomalies.

Claims

1. An anomaly detection circuit based on differential signals, characterized by: The main control MCU module, the differential IC module, and the comparator LM339 module are included. The main control MCU module outputs signals through TXD1 and TXD2 pins, which are transmitted to the differential IC module. In the differential IC module, the input signals are converted into differential signals of TXD1+, TXD1-, TXD2+, and TXD2- and then sent to the comparator LM339 module. In the LM339 module, the differential signals are further processed and compared, and the processing results are fed back to the main control MCU module through CHECK_TXD1+, CHECK_TXD1-, CHECK_TXD2+, and CHECK_TXD2- pins. The main control MCU module is used to execute program instructions, process input and output signals, and manage the running state of the system. It drives the differential IC module by sending control signals to perform differential transmission of signals. The main control MCU module is also used to receive feedback signals from the comparator LM339 module. The differential IC module is used to convert single-ended signals output by the main control MCU module into differential signals for circuit conditioning and protection. The comparator LM339 module is used to compare and process differential signals output by the differential IC module and convert the differential signals into single-ended signals. The comparison results are used to trigger alarms and adjust system parameters. The comparator LM339 module is also used to feed back the comparison results to the main control MCU module.

2. The anomaly detection circuit based on differential signal according to claim 1, characterized in that: The main control MCU module includes REFC, which is connected to one end of resistor R932 and resistor R933. The other end of resistor R932 is connected to 3V3_MCU, and the other end of resistor R932 is connected to ground.

3. The differential signal based anomaly detection circuit of claim 1, wherein: The differential IC module includes chip U2. The 1st pin of chip U2 is connected to TXD1, the 7th pin of chip U2 is connected to TXD2, the 4th pin and the 12th pin of chip U2 are both connected to ground, the 2nd pin of chip U2 is linked to the 5th pin of the resistor network, the 3rd pin of chip U2 is linked to the 6th pin of the resistor network, the 5th pin of chip U2 is linked to the 7th pin of the resistor network, and the 6th pin of chip U2 is linked to the 8th pin of the resistor network.

4. The differential signal based anomaly detection circuit of claim 3, wherein: The 4th pin of the resistor network is connected at one end of the capacitor C562 and the intersection of the 2nd pin of the resistor network, the 3rd pin of the resistor network is connected at one end of the capacitor C561 and the 6th pin of the chip BLN3, the 2nd pin of the resistor network is connected at one end of the capacitor C562 and the 7th pin of the chip BLN3, the 1st pin of the resistor network is connected at the other end of the capacitor C562 and the 8th pin of the chip BLN3, the other end of the capacitor C561 is connected at one end of the capacitor C562 and the 5th pin of the chip BLN3, the 4th pin of the chip BLN3 is connected with TXD1+, the 3rd pin of the chip BLN3 is connected with TXD1-, the 2nd pin of the chip BLN3 is connected with TXD2-, and the 1st pin of the chip BLN3 is connected with TXD2+.

5. The differential signal based anomaly detection circuit of claim 1, wherein: The comparator LM339 module comprises a comparator U1, one end of the 9th pin of the comparator U1 is connected with the ground through a resistor R940, the other end of the resistor is also connected with the ground through a diode D158, one end of the diode is connected with TXD1+ through a resistor R938, the 8th pin of the comparator U1 is connected at the intersection of a resistor R946 and a resistor R947, one end of the resistor R947 is also connected with the ground, the 12th pin of the comparator U1 is connected with the ground, the 3rd pin of the comparator U1 is connected at the intersection of 3V3_MCU and one end of a resistor R941, one end of the 3V3_MCU is also connected with the ground through a capacitor C571, the 14th pin of the comparator U1 is connected at the intersection of one end of a resistor R944 and the other end of the resistor R941, the other end of the resistor R944 is connected with the ground through a capacitor C572, and the other end of the resistor R944 is also connected with CHECK_TXD1+.

6. The differential signal based anomaly detection circuit of claim 5, wherein: The 5th pin of the comparator U1 is connected with the ground through a resistor R942, one end of the resistor is also connected with the ground through a diode D159, one end of the diode is connected with TXD1- through a resistor R939, the 3rd pin of the comparator U1 is connected at the intersection of 3V3_MCU and one end of a resistor R943, the 2nd pin of the comparator U1 is connected at the intersection of one end of a resistor R945 and the other end of the resistor R943, the other end of the resistor R945 is connected with the ground through a capacitor C573, and the other end of the resistor R945 is also connected with CHECK_TXD1-.

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