Monitoring system and method for head-up displays

Abstract

A monitoring system and method for a head-up display. The monitoring system for a head-up display includes a microcontroller, a driver, a plurality of light emitting diodes, and a monitoring circuit. The microcontroller is configured to output a pulse width modulation setting. The driver is connected to the microcontroller. The driver is configured to receive the pulse width modulation setting and output a pulse width signal based on the pulse width modulation setting. The plurality of light emitting diodes is connected to the driver. The plurality of light emitting diodes is configured to emit light and output a first pulse width modulation signal upon receiving the pulse width signal. The monitoring circuit is connected to the plurality of light emitting diodes. The monitoring circuit is configured to adjust the first pulse width modulation signal to a second pulse width modulation signal and output the second pulse width modulation signal to the microcontroller. The microcontroller is configured to determine whether the driver is malfunctioning based on the second pulse width modulation signal and the pulse width modulation setting.

Description

TECHNICAL FIELD

[0001] The present application relates to a monitoring system and method, and particularly relates to a monitoring system and method for a head-up display. BACKGROUND

[0002] In a head-up display for a vehicle, a driver is usually used to drive a light-emitting diode to emit light, project driving-related information on a lens and reflect the information to the user's eyes by the lens, so that the user can obtain driving-related information without lowering his head. In the head-up display, a pulse width modulation (PWM) technique is generally used to adjust the duty cycle of a square wave to regulate the brightness of light emitted by the light-emitting diode.

[0003] However, when the driver fails or is damaged to cause the duty cycle of the square wave output by the driver to be abnormal, the brightness of the light-emitting diode will also be abnormal, which will generate glare in the user's line of sight and affect the safety of driving the vehicle. The driver on the market cannot detect whether the duty cycle of the pulse width modulation signal output by the driver is abnormal in time. Therefore, in order to improve the safety of driving, a driver monitoring system and method for a head-up display are needed. SUMMARY

[0004] The present application relates to a monitoring system and method for a head-up display, which can determine whether the driver for monitoring the head-up display fails and respond in real time to reduce the impact on the user.

[0005] According to an embodiment of the present application, a monitoring system for a head-up display is provided. The monitoring system includes a microcontroller, a driver, a plurality of light-emitting diodes, and a monitoring circuit. The microcontroller is configured to output a pulse width modulation (PWM) setting value. The driver is connected to the microcontroller. The driver is configured to receive the PWM setting value and output a pulse width signal according to the PWM setting value to control the brightness of the plurality of light-emitting diodes. The plurality of light-emitting diodes are connected to the driver. The plurality of light-emitting diodes are configured to emit light and output a first PWM signal after receiving the pulse width signal. The monitoring circuit is connected to the plurality of light-emitting diodes. The monitoring circuit is configured to adjust the first PWM signal to a second PWM signal and output the second PWM signal to the microcontroller. The microcontroller is configured to determine whether the driver fails according to the second PWM signal and the PWM setting value.

[0006] According to another embodiment of the present application, a monitoring method for a head-up display is provided. The monitoring method for a head-up display comprises the following steps. A pulse width modulation setting value is outputted by a microcontroller. The pulse width modulation setting value is received by a driver, and a pulse width signal is outputted by the driver according to the pulse width modulation setting value to control the brightness of a plurality of light emitting diodes. The driver is connected to the microcontroller. The pulse width signal is received by the plurality of light emitting diodes to emit light, and a first pulse width modulation signal is outputted by the plurality of light emitting diodes. The plurality of light emitting diodes are connected to the driver. The first pulse width modulation signal is adjusted to a second pulse width modulation signal by a monitoring circuit, and the second pulse width modulation signal is outputted to the microcontroller. Whether the driver is failed is determined by the microcontroller according to the second pulse width modulation signal and the pulse width modulation setting value.

[0007] The present application is described in detail below with reference to the attached drawing figures and specific embodiments. It is to be noted, however, that the application is not limited to the specific embodiments described below, but rather, claims full protection encompassing any and all embodiments within the scope of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 A block diagram of a monitoring system for a head-up display according to an embodiment is shown.

[0009] Figure 2 A flowchart of a monitoring method for a head-up display according to an embodiment is shown.

[0010] Figure 3 An internal circuit diagram of a monitoring system for a head-up display according to an embodiment is shown.

[0011] Figure 4 An operation flowchart of a power switch in a monitoring system for a head-up display according to an embodiment is shown.

[0012] Figure 5 An input terminal switching flowchart of a microcontroller according to FIG. 3 is shown.

[0013] Wherein, the reference signs are:

[0014] 100, 300: monitoring system

[0015] 110, 310: microcontroller

[0016] 120, 320: driver

[0017] 130, 330: monitoring circuit

[0018] 140, 340: power switch

[0019] 150, 350: output voltage monitoring circuit

[0020] 160, 360: voltage divider

[0021] 170, 370: low pass filter

[0022] 200, 400, 500: flow chart

[0023] ADC_IN: second input terminal

[0024] C1, C2: capacitor

[0025] LED1, LED2, LED3...LEDn: light emitting diode

[0026] LED_A, LED_K: loop

[0027] n1, n2, n3, n4: node

[0028] OPA: operational amplifier

[0029] POWER: power supply

[0030] PWM_1: first pulse width modulation signal

[0031] PWM_2: second pulse width modulation signal

[0032] PWM_IN: first input terminal

[0033] PWR_EN: power control signal

[0034] PWM_SET: pulse width modulation setting value

[0035] R1, R2, R3, R4, R5, R6, R7: resistor

[0036] S210, S220, S230, S240, S250, S260, S270, S410, S420, S430, S510,

[0037] S520, S530: step

[0038] VDD: driving voltage

[0039] Vi: input voltage

[0040] Vo: output voltage DETAILED DESCRIPTION

[0041] The structural principle and working principle of the present application will be described in detail below in combination with the drawings:

[0042] Please refer to Figure 1Fig. 1 is a block diagram illustrating a monitoring system 100 for a head-up display according to an embodiment. The monitoring system 100 includes a microcontroller 110, a driver 120, a monitoring circuit 130, a power switch 140, light emitting diodes LED1, LED2,..., LEDn, an output voltage monitoring circuit 150 including a voltage divider 160 and a low pass filter 170. The microcontroller 110 is used to control the whole monitoring system 100. The driver 120 is used to drive the light emitting diodes LED1,..., LEDn to emit light. The monitoring circuit 130 is used to detect and adjust the pulse width modulation signal of the loop LED_K. The power switch 140 is used to output a driving voltage VDD to the driver 120 to operate.

[0043] In this embodiment, the microcontroller 110 sends a pulse width modulation setting value PWM_SET to the driver 120 through a serial bus (e.g. I2C). The driver 120 receives the pulse width modulation setting value PWM_SET and outputs a pulse width signal according to the pulse width modulation setting value PWM_SET to control the light emitting diodes to emit light. The pulse width signal is input to the light emitting diodes LED1,..., LEDn through the loop LED_A. The light emitting diodes LED1,..., LEDn receive the pulse width signal and emit light. The first pulse width modulation signal PWM_1 is output to the driver 120 and the monitoring circuit 130 through the loop LED_K.

[0044] The monitoring circuit 130 adjusts the first pulse width modulation signal PWM_1 to the second pulse width modulation signal PWM_2 and outputs the second pulse width modulation signal PWM_2 to the microcontroller 110. The microcontroller 110 determines whether the driver 120 is failed according to the second pulse width modulation signal PWM_2 and the pulse width modulation setting value PWM_SET.

[0045] The power switch 140 receives a power source POWER and a power control signal PWR_EN from the microcontroller 110. The microcontroller 110 controls whether to disconnect the power switch 140 through the power control signal PWR_EN. The voltage divider 160 in the output voltage monitoring circuit 150 receives the pulse width signal, reduces the voltage of the received pulse width signal, and outputs a voltage reduction signal. The low pass filter 170 receives the voltage reduction signal, filters the voltage reduction signal, and outputs a direct current voltage to the microcontroller 110. The microcontroller 110 determines whether the driver 120 is failed according to the direct current voltage.

[0046] Figure 2A flowchart 200 illustrates a control method for a driver monitoring system according to an embodiment. In step S210, the microcontroller 110 determines whether the voltage output by the driver 120 is greater than a DC voltage setting value (e.g., 28 volts ± 2%). If it is greater, the process proceeds to step S270, where the microcontroller 110 determines that the driver has failed. If the voltage is not greater, the process proceeds to step S220.

[0047] In step S220, the microcontroller 110 outputs a pulse width modulation setting value PWM_SET to the driver 120. The pulse width modulation setting value PWM_SET has a square wave duty cycle setting value. The square wave duty cycle setting value represents the proportion of the low voltage of the output square wave in one cycle in the pulse width modulation setting value PWM_SET.

[0048] Next, in step S230, the driver 120 outputs the corresponding pulse width signal according to the pulse width modulation setting value PWM_SET.

[0049] Then, in step S240, LEDs LED1 to LEDn receive the pulse width signal and emit light, outputting a corresponding first pulse width modulation signal PWM_1. The first pulse width modulation signal PWM_1 has a square wave duty cycle measurement value. The square wave duty cycle measurement value is the proportion of the low voltage of the output square wave in one cycle of the first pulse width modulation signal PWM_1 actually output by LEDs LED1 to LEDn.

[0050] However, the first pulse width modulation signal PWM_1 output by LED1 to LEDn is often distorted and cannot be interpreted. Figure 1 Taking the waveform shown as an example, when the first pulse width modulation signal PWM_1 is an incomplete square wave, the microcontroller 110 cannot accurately determine whether the output at a specific time point is a high-potential signal or a low-potential signal, causing an error in the calculation of the square wave duty cycle measurement value. This further leads to the microcontroller 110 being unable to accurately determine whether the driver 120 has failed. Therefore, it is necessary to adjust the waveform of the first pulse width modulation signal PWM_1 to a square wave that the microcontroller 110 can correctly interpret before inputting it into the microcontroller 110 so that it can interpret the correct square wave duty cycle measurement value.

[0051] Furthermore, if the voltage value of the input signal to the microcontroller 110 is greater than the voltage threshold that the microcontroller 110 can withstand, it may cause the microcontroller 110 to fail or malfunction. Therefore, it is also necessary to adjust the maximum voltage value of the first pulse width modulation signal PWM_1.

[0052] Therefore, in step S250, the monitoring circuit 130 receives the first pulse width modulation signal PWM_1 and adjusts the first pulse width modulation signal PWM_1 to a second pulse width modulation signal PWM_2. The second pulse width modulation signal PWM_2 is a full square wave, and the highest voltage value of the second pulse width modulation signal PWM_2 is lower than the first pulse width modulation signal PWM_1 and lower than the voltage threshold of the microcontroller 110.

[0053] Then, in step S260, the microcontroller 110 compares the square wave duty cycle measurement value of the second pulse width modulation signal PWM_2 in step S250 with the square wave duty cycle setting value of the output pulse width modulation setting value PWM_SET in step S220. If the square wave duty cycle measurement value is higher than a predetermined multiple of the square wave duty cycle setting value, the microcontroller 110 determines that the driver 120 is failed and proceeds to step S270. If the square wave duty cycle measurement value is lower than a predetermined multiple of the square wave duty cycle setting value, the microcontroller 110 determines that the driver 120 is not failed and returns to step S250.

[0054] In this way, by adjusting the first pulse width modulation signal PWM_1 to the second pulse width modulation signal PWM_2 in step S240, the microcontroller 110 can accurately determine whether the driver 120 is failed.

[0055] Figure 3 A diagram of a driver monitoring system 300 and internal circuit of a monitoring circuit 330 according to an embodiment is shown. The monitoring system 300 includes a microcontroller 310, a driver 320, light emitting diodes LED1-LEDn, and the monitoring circuit 330, a power switch 340, and a voltage divider 360 and a low pass filter 370 in an output voltage monitoring circuit 350. The microcontroller 310 outputs a pulse width modulation setting value PWM_SET with a square wave duty cycle setting value to the driver 320. The driver 320 outputs a corresponding pulse width signal to the light emitting diodes LED1-LEDn in a loop LED_A according to the pulse width modulation setting value PWM_SET, and the light emitting diodes emit light and output a first pulse width modulation signal PWM_1 after receiving the pulse width signal. The first pulse width modulation signal PWM_1 is input to the monitoring circuit 330 through a node n1.

[0056] The monitoring circuit 330 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a first capacitor C1 coupled in a loop LED_K at a node n1. The second resistor R2 is coupled in series with the first resistor R1 and to a positive input of an operational amplifier OPA, an output of the operational amplifier OPA is fed back to a negative input, and the output is coupled to the third resistor R3. The third resistor R3 is coupled to a first input PWM_IN of the microcontroller 310 via nodes n2, n3. The fourth resistor R4 and the first capacitor C1 are coupled at one end to the nodes n2, n3 between the third resistor R3 and the input of the microcontroller 310 and at the other end to ground. The fifth resistor R5 is coupled from a node n4 to a second input ADC_IN of the microcontroller 310. The voltage divider 360 has a sixth resistor R6 and a seventh resistor R7, and the low pass filter 370 has a second capacitor C2.

[0057] The monitoring circuit 330 can adjust the first pulse width modulation signal PWM_1, which originally generates a distorted square wave and has a maximum voltage value greater than the voltage threshold of the microcontroller 310, to a second pulse width modulation signal PWM_2 having a complete square wave and a maximum voltage value less than the voltage threshold of the microcontroller 310. The microcontroller 310 receives the second pulse width modulation signal PWM_2 through the first input PWM_IN and determines whether the driver 320 is malfunctioning based on the second pulse width modulation signal PWM_2 and the pulse width modulation setting value PWM_SET. In addition, the monitoring system 300 has a power switch 340 coupled between the microcontroller 310 and the driver 320. If the microcontroller 310 determines that the voltage output by the driver 320 is greater than the DC voltage setting value (e.g., 28 volts ± 2%), it means that the driver 320 is in an abnormal working state. At this time, the microcontroller 310 controls the power switch 340 to be turned off through the power control signal PWR_EN.

[0058] Figure 4 FIG. 4 shows a flowchart of the operation of the power switch in the monitoring system according to an embodiment. For example, in step S410, the power switch 140 outputs the driving voltage VDD to the driver 120 to operate. Figure 1

[0059] Then, in step S420, the microcontroller 110 determines whether the driver 120 is malfunctioning based on the square wave duty cycle measurement value of the second pulse width modulation signal PWM_2 and the square wave duty cycle setting value of the pulse width modulation setting value PWM_SET. If the driver 120 is not malfunctioning, it returns to step S410, and the power switch 140 continuously outputs the driving voltage VDD to the driver 120.

[0060] ​In step S420, if the microcontroller 110 determines that the driver 120 is malfunctioning, the microcontroller 120 sends a power control signal PWR_EN to turn off the power switch 140, and the power switch 140 stops outputting the driving voltage VDD to the driver 120. In this way, when the driver 120 malfunctions and outputs an abnormal pulse width signal, causing the light emitting diodes LED1-LEDn to abnormally emit light, the microcontroller 110 can turn off the power switch 140 in real time, so that the driver 120 stops outputting the pulse width signal, thereby avoiding the abnormal light emission of the light emitting diodes LED1-LEDn from affecting the user.

[0061] Through the above-mentioned embodiments, when using a head-up display, especially a head-up display for vehicles, the abnormal light emission of the light emitting diodes LED1-LEDn can be suppressed within a very short time (e.g., within 50 ns), thereby avoiding the glare caused by the abnormal light emission from affecting the driver's line of sight.

[0062] Figure 5 According to the above-mentioned embodiments, the microcontroller 310 can quickly determine whether the driver 120 is malfunctioning, and can turn off the power switch 140 to avoid the light emitting diodes LED1-LEDn from abnormally emitting light due to receiving the pulse width signal sent by the malfunctioning driver 120, thereby effectively improving the safety of use or driving. Figure 3 The flowchart 500 of the input switching of the microcontroller 310 is shown in FIG. 5. In step S510, the microcontroller 310 determines the output pulse width modulation setting value PWM_SET. If the microcontroller 310 determines in step S510 that the output pulse width modulation setting value PWM_SET is equal to 1% to 99% of the square wave duty cycle setting value, the microcontroller 310 will execute step S520 to receive the second pulse width modulation signal PWM_2 from the monitoring circuit 330 through the first input PWM_IN.

[0063] If the microcontroller 310 determines in step S510 that the output pulse width modulation setting value PWM_SET is equal to 0% or 100% of the square wave duty cycle setting value, a continuous voltage signal between the low voltage and the high voltage will be generated on the loop LED_K, and at this time the first input PWM_IN of the microcontroller 310 cannot effectively determine the second pulse width modulation signal PWM_2. At this time, the microcontroller 310 will execute step S530 to read the voltage value through the second input ADC_IN to determine whether the square wave duty cycle measurement value of the second pulse width modulation signal PWM_2 is 0% or 100%, so as to ensure the accuracy of the determination of the microcontroller 310.

[0064] In this way, through the above-mentioned monitoring system and monitoring method for the head-up display, the microcontroller can quickly determine whether the driver is malfunctioning, and can turn off the power switch to avoid the light emitting diodes from abnormally emitting light due to receiving the pulse width signal sent by the malfunctioning driver, thereby further avoiding the generation of glare on the head-up display and affecting the user or the driver's line of sight, and effectively improving the safety of use or driving.

[0065] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, and these corresponding changes and modifications shall all belong to the protection scope of the claims of the present application.

Claims

1. A monitoring system for a head-up display, characterized by, The monitoring system comprises: a microcontroller for outputting a pulse width modulation setting value; a driver connected to the microcontroller, the driver receiving the pulse width modulation setting value and outputting a pulse width signal according to the pulse width modulation setting value; a plurality of light emitting diodes connected to the driver, the light emitting diodes emitting light after receiving the pulse width signal and outputting a first pulse width modulation signal; and a monitoring circuit connected to the light emitting diodes, the monitoring circuit adjusting the first pulse width modulation signal to a second pulse width modulation signal and outputting the second pulse width modulation signal to the microcontroller; wherein the microcontroller determines whether the driver is failed according to the second pulse width modulation signal and the pulse width modulation setting value; wherein the pulse width modulation setting value is a square wave duty cycle setting value; wherein if a square wave duty cycle measurement value of the second pulse width modulation signal is higher than a predetermined multiple of the square wave duty cycle setting value, the microcontroller determines that the driver is failed.

2. The monitoring system of claim 1, wherein, wherein the second pulse width modulation signal is a square wave.

3. The monitoring system of claim 1, wherein, wherein a highest voltage value of the second pulse width modulation signal is lower than a highest voltage value of the first pulse width modulation signal and a voltage threshold value of the microcontroller.

4. The monitoring system of claim 1, wherein, wherein the microcontroller has a first input and a second input, the microcontroller receives the second pulse width modulation signal through the first input, and when the square wave duty cycle setting value of the pulse width modulation setting value is equal to 0% or 100%, the microcontroller receives the second pulse width modulation signal through the second input.

5. The monitoring system of claim 1, wherein, wherein the monitoring system further comprises a power switch connected to a power source and the driver, and when the microcontroller determines that the driver is failed, the microcontroller disconnects the power switch.

6. The monitoring system of claim 1, wherein, wherein the monitoring system further comprises an output voltage monitoring circuit, the output voltage monitoring circuit comprises: a voltage divider connected to the driver, the voltage divider receiving the pulse width signal, the voltage divider reducing a voltage of the received pulse width signal and outputting a voltage reduced signal; and a low pass filter connected to the voltage divider and the microcontroller, the low pass filter receiving the voltage reduced signal, the low pass filter filtering the voltage reduced signal and outputting a direct current voltage to the microcontroller; wherein the microcontroller determines whether the driver is failed according to the direct current voltage.

7. A monitoring method for a head-up display, characterized by, The monitoring method comprises: outputting a pulse width modulation setting value by a microcontroller; receiving the pulse width modulation setting value by a driver and outputting a pulse width signal according to the pulse width modulation setting value, the driver being connected to the microcontroller; emitting light after receiving the pulse width signal by a plurality of light emitting diodes and outputting a first pulse width modulation signal, the light emitting diodes being connected to the driver; adjusting the first pulse width modulation signal to a second pulse width modulation signal by a monitoring circuit and outputting the second pulse width modulation signal to the microcontroller; and determining whether the driver is failed by the microcontroller according to the second pulse width modulation signal and the pulse width modulation setting value. The pulse width modulation setting value is a square wave duty cycle setting value in the step of outputting the pulse width modulation setting value by the microcontroller. If a square wave duty cycle measurement value of the second pulse width modulation signal is higher than a predetermined multiple of the square wave duty cycle setting value, the microcontroller determines that the driver is failed in the step of determining whether the driver is failed by the microcontroller according to the second pulse width modulation signal and the pulse width modulation setting value.

8. The monitoring method of claim 7, wherein, The second pulse width modulation signal is a square wave in the step of adjusting the first pulse width modulation signal to the second pulse width modulation signal by the monitoring circuit and outputting the second pulse width modulation signal to the microcontroller.

9. The monitoring method of claim 7, wherein, The highest voltage value of the second pulse width modulation signal is lower than the highest voltage value of the first pulse width modulation signal and a voltage threshold of the microcontroller in the step of adjusting the first pulse width modulation signal to the second pulse width modulation signal by the monitoring circuit.

10. The monitoring method of claim 7, wherein, The microcontroller has a first input terminal and a second input terminal in the step of determining whether the driver is failed by the microcontroller according to the second pulse width modulation signal and the pulse width modulation setting value. The microcontroller receives the second pulse width modulation signal by the first input terminal. When the square wave duty cycle setting value of the pulse width modulation setting value is equal to 0% or 100%, the microcontroller receives the second pulse width modulation signal by the second input terminal.

11. The monitoring method of claim 7, wherein, The microcontroller disconnects a power supply and a power switch of the driver when the microcontroller determines that the driver is failed in the step of determining whether the driver is failed by the microcontroller according to the second pulse width modulation signal and the pulse width modulation setting value.

12. The monitoring method of claim 7, wherein, The monitoring circuit further comprises: a voltage divider receiving the pulse width signal, the voltage divider reducing voltage of the received pulse width signal and outputting a voltage reduced signal; and a low pass filter receiving the voltage reduced signal, the low pass filter filtering the voltage reduced signal and outputting a direct current voltage to the microcontroller; wherein the microcontroller determines whether the driver is failed according to the direct current voltage.

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