Control circuit for solving HUD bursting caused by single-point failure of dimming circuit

Abstract

The invention discloses a control circuit for solving HUD bursting caused by single-point failure of a dimming circuit, and relates to the technical field of LED control, the control circuit comprises a constant current source circuit and a redundant circuit, the constant current source circuit uses a control chip to adjust the brightness of an LED lamp through PWM waves, the redundant circuit is used for protecting the constant current source circuit, and the redundant circuit is used for controlling the LED lamp to be bright. The LED lamp is in a controlled state when single-point failure occurs in the constant-current source circuit, burst lighting is prevented, the constant-current source circuit comprises an operational amplifier U1 and an MOS tube Q1, a drain electrode of the MOS tube Q1 is connected with the LED lamp, and a grid electrode of the MOS tube Q1 is connected with a pin 1 of the operational amplifier U1 and a collector electrode of a triode D. According to the control circuit, redundant device design is added, so that the LED lamp is in a controlled state, and burst lighting is prevented. The problem that the brightness of the LED lamp in the dimming circuit is influenced by single-point failure of a device in the dimming circuit is solved, the brightness of the LED lamp is always in a controlled state, screen extinguishing caused by failure of a single MOS tube is prevented, and the situation that the screen bursts is effectively prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of LED control, and in particular to a control circuit for solving the problem of a HUD suddenly lighting up due to a single point failure of a dimming circuit. Background Art

[0002] At present, most of the HUDs used in aviation aircraft require the use of LED backlights. In order to keep the brightness of LEDs consistent at high and low temperatures, a constant current source circuit based on MOS tubes and operational amplifiers is used at low temperatures (see the attached figure). Figure 1 As shown), the control chip controls the brightness adjustment of the backlight through the PWM wave, and the resistors R1 and R2 control the current of the backlight LED lamp.

[0003] When any device in the above circuit fails, the control circuit will fail at a single point, resulting in uncontrollable backlight. For example, if the source and drain of MOS tube Q1 are turned on, the brightness of the LED lamp will be out of control, making the screen brightness extremely bright. Since this digital image source is projected directly in front of the pilot, the pilot's naked eye will be exposed to about 10,000 cd / m 2 The brightness stimulation will affect the flight safety. Since the onboard equipment has mutual backup function, the black screen due to image source failure can be accepted, but the sudden brightness caused by image source failure cannot be accepted. Therefore, a control circuit is proposed to solve the problem of HUD sudden brightness caused by single point failure of dimming circuit. Summary of the invention

[0004] The purpose of the present invention is to solve the problems in the prior art and to propose a control circuit to solve the problem of HUD brightening caused by single point failure of the dimming circuit.

[0005] A control circuit for solving the problem of HUD bursting due to single-point failure of a dimming circuit, comprising a constant current source circuit and a redundant circuit. The constant current source circuit uses a control chip to adjust the brightness of an LED lamp through a PWM wave. The redundant circuit is used to protect the constant current source circuit. When a single-point failure occurs in the constant current source circuit, the LED lamp is placed in a controlled state to prevent bursting.

[0006] Preferably, the constant current source circuit includes an operational amplifier U1 and a MOS tube Q1, the drain of the MOS tube Q1 is connected to an LED lamp, the gate of the MOS tube Q1 is respectively connected to pin 1 of the operational amplifier U1 and the collector of the transistor D, the base of the transistor D controls the PWM interface of the chip, the emitter of the transistor D is grounded, the pin 3 of the operational amplifier U1 is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R1 is connected to the power supply, the other end of the resistor R2 is grounded, the pin 4 of the operational amplifier U1 is grounded, and the pin 8 of the operational amplifier U1 is connected to the power supply.

[0007] Preferably, the redundant circuit comprises a MOS tube Q2, a MOS tube Q3, a MOS tube Q4 and an operational amplifier U2, the drain of the MOS tube Q2 is respectively connected to the drain of the MOS tube Q1 and the LED lamp, the gate of the MOS tube Q2 is respectively connected to the pin 1 of the operational amplifier U1 of the gate of the MOS tube Q1, the drain of the MOS tube Q3 is connected to the source of the MOS tube Q1, the drain of the MOS tube Q4 is connected to the source of the MOS tube Q2, the pin 1 of the operational amplifier U2 is respectively connected to the gate of the MOS tube Q3 and the gate of the MOS tube Q4, and the pin 2 of the operational amplifier U1 is respectively connected to the gate of the MOS tube Q3 and the gate of the MOS tube Q4. The pins 2 of the operational amplifier U2, the source of the MOS tube Q3, the source of the MOS tube Q4, one end of the resistor R5 and one end of the resistor R6 are respectively connected, the other end of the resistor R5 is connected to one end of the resistor R7, the other end of the resistor R6 is connected to one end of the resistor R8, the other end of the resistor R7 is connected to the other end of the resistor R8 and connected to the ground, the pins 3 of the operational amplifier U2 are respectively connected to one end of the resistor R3 and one end of the resistor R4, the other end of the resistor R3 is connected to the power supply, the other end of the resistor R4 is grounded, the pin 4 of the operational amplifier U2 is grounded, and the pin 8 of the operational amplifier U2 is connected to the power supply.

[0008] Preferably, the ratio of the resistor R1 to the resistor R2 is the same as the ratio of the resistor R3 to the resistor R4.

[0009] Compared with the prior art, the present invention has the following advantages:

[0010] The control circuit of the present invention adds a redundant device design, which solves the impact of single-point failure of the device in the dimming circuit on the brightness of the LED lamp in the circuit, and always keeps the brightness of the LED lamp in a controlled state, which not only prevents the screen from being turned off due to the failure of a single MOS tube, but also effectively prevents the screen from being overly bright, thereby ensuring the flight safety of aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is the principle diagram of the constant current source circuit of the present invention.

[0012] Figure 2 It is the control circuit principle diagram of the present invention. DETAILED DESCRIPTION

[0013] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0014] Reference Figure 2As shown, a control circuit for solving the problem of HUD bursting due to single-point failure of a dimming circuit is characterized in that it includes a constant current source circuit and a redundant circuit. The constant current source circuit uses a control chip to adjust the brightness of an LED lamp through a PWM wave. The redundant circuit is used to protect the constant current source circuit. When a single-point failure occurs in the constant current source circuit, the LED lamp is in a controlled state to prevent bursting.

[0015] In this embodiment, the constant current source circuit includes an operational amplifier U1 and a MOS tube Q1, the drain of the MOS tube Q1 is connected to an LED lamp, the gate of the MOS tube Q1 is respectively connected to pin 1 of the operational amplifier U1 and the collector of the transistor D, the base of the transistor D controls the PWM interface of the chip, the emitter of the transistor D is grounded, the pin 3 of the operational amplifier U1 is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R1 is connected to the power supply, the other end of the resistor R2 is grounded, the pin 4 of the operational amplifier U1 is grounded, and the pin 8 of the operational amplifier U1 is connected to the power supply.

[0016] In this embodiment, the redundant circuit includes MOS tube Q2, MOS tube Q3, MOS tube Q4 and operational amplifier U2, the drain of MOS tube Q2 is respectively connected to the drain of MOS tube Q1 and the LED lamp, the gate of MOS tube Q2 is respectively connected to the pin 1 of the operational amplifier U1 of the gate of MOS tube Q1, the drain of MOS tube Q3 is connected to the source of MOS tube Q1, the drain of MOS tube Q4 is connected to the source of MOS tube Q2, the pin 1 of the operational amplifier U2 is respectively connected to the gate of MOS tube Q3 and the gate of MOS tube Q4, and the pin 2 of the operational amplifier U1 is respectively connected to the gate of MOS tube Q3 and the gate of MOS tube Q4. Pin 2 of the operational amplifier U2, the source of the MOS tube Q3, the source of the MOS tube Q4, one end of the resistor R5 and one end of the resistor R6 are respectively connected, the other end of the resistor R5 is connected to one end of the resistor R7, the other end of the resistor R6 is connected to one end of the resistor R8, the other end of the resistor R7 is connected to the other end of the resistor R8 and connected to the ground, pin 3 of the operational amplifier U2 is respectively connected to one end of the resistor R3 and one end of the resistor R4, the other end of the resistor R3 is connected to the power supply, the other end of the resistor R4 is grounded, pin 4 of the operational amplifier U2 is grounded, and pin 8 of the operational amplifier U2 is connected to the power supply.

[0017] In this embodiment, the ratio of the resistor R1 to the resistor R2 is the same as the ratio of the resistor R3 to the resistor R4.

[0018] The working process and principle of the present invention are as follows:

[0019] Because most failures on aircraft are single-point failures, only single-point failures are considered below.

[0020] When the source and drain of the MOS tube Q1 fail to open circuit, the current flows through the MOS tube Q2, which does not affect the airborne use. Similarly, since the MOS tube Q3 and the MOS tube Q4 are redundant designs, the airborne use is not affected when the MOS tube Q3 and the MOS tube Q4 fail to open circuit. When one of the resistors R5, R6, R7 and R8 fails to open circuit, it will only cause the equivalent resistance value to increase, and will only cause the current to be reduced to half of the original value.

[0021] When the source and drain of MOS tube Q3 and MOS tube Q4 fail due to short circuit, MOS tube Q1 and MOS tube Q2 are in a controlled state, so it does not affect the onboard use; when one of MOS tube Q1 and MOS tube Q2 fails due to short circuit, the maximum brightness of the LED lamp is limited by MOS tube Q3 and MOS tube Q4, where the ratio of resistor R3 and resistor R4 is consistent with the ratio of resistor R1 and resistor R2, and the LED lamp will only be under maximum brightness control; when one of resistors R5, R6, R7 and R8 fails due to short circuit, the brightness of the LED lamp is only 133% of the current brightness, and the brightness of the LED lamp is also controlled by duty cycle dimming, and the brightness will not be uncontrollable, effectively preventing the screen from being overly bright.

[0022] Other single-point failures in the circuit are equivalent to single-point short circuit and open circuit effects that affect the MOS tube.

[0023] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A control circuit to solve the problem of HUD bursting due to single-point failure of dimming circuit, characterized by: It includes a constant current source circuit and a redundant circuit. The constant current source circuit uses a control chip to adjust the brightness of the LED lamp through a PWM wave. The redundant circuit is used to protect the constant current source circuit. When a single point failure occurs in the constant current source circuit, the LED lamp is in a controlled state to prevent excessive brightness.

2. A control circuit for solving the problem of HUD brightening caused by single-point failure of dimming circuit according to claim 1, characterized in that: The constant current source circuit includes an operational amplifier U1 and a MOS tube Q1, the drain of the MOS tube Q1 is connected to an LED lamp, the gate of the MOS tube Q1 is respectively connected to pin 1 of the operational amplifier U1 and the collector of the transistor D, the base of the transistor D controls the PWM interface of the chip, the emitter of the transistor D is grounded, the pin 3 of the operational amplifier U1 is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R1 is connected to a power supply, the other end of the resistor R2 is grounded, the pin 4 of the operational amplifier U1 is grounded, and the pin 8 of the operational amplifier U1 is connected to the power supply.

3. A control circuit for solving the problem of HUD brightening caused by single-point failure of dimming circuit according to claim 2, characterized in that: The redundant circuit comprises MOS tube Q2, MOS tube Q3, MOS tube Q4 and operational amplifier U2, the drain of MOS tube Q2 is respectively connected to the drain of MOS tube Q1 and LED lamp, the gate of MOS tube Q2 is respectively connected to the pin 1 of operational amplifier U1 of the gate of MOS tube Q1, the drain of MOS tube Q3 is connected to the source of MOS tube Q1, the drain of MOS tube Q4 is connected to the source of MOS tube Q2, the pin 1 of operational amplifier U2 is respectively connected to the gate of MOS tube Q3 and the gate of MOS tube Q4, the pin 2 of operational amplifier U1 is respectively connected to the gate of MOS tube Q3 and the gate of MOS tube Q4, Pin 2 of the operational amplifier U2, the source of the MOS tube Q3, the source of the MOS tube Q4, one end of the resistor R5 and one end of the resistor R6 are connected, the other end of the resistor R5 is connected to one end of the resistor R7, the other end of the resistor R6 is connected to one end of the resistor R8, the other end of the resistor R7 is connected to the other end of the resistor R8 and connected to the ground, pin 3 of the operational amplifier U2 is respectively connected to one end of the resistor R3 and one end of the resistor R4, the other end of the resistor R3 is connected to the power supply, the other end of the resistor R4 is grounded, pin 4 of the operational amplifier U2 is grounded, and pin 8 of the operational amplifier U2 is connected to the power supply.

4. A control circuit for solving the problem of HUD bursting due to single point failure of dimming circuit according to claim 3, characterized in that: The ratio of the resistor R1 to the resistor R2 is the same as the ratio of the resistor R3 to the resistor R4.

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