PIS screen LED backlight driver testing device

Abstract

The utility model discloses a testing device for an LED backlight driver of a PIS screen. The testing device comprises an isolation voltage and current measuring module I, a startup and shutdown testing module, a PWM brightness testing module, an isolation voltage and current measuring module II and an isolation voltage and current measuring module III. According to the utility model, through arranging the isolation voltage and current measurement module 1, the PWM brightness test module, the isolation voltage and current measurement module 2, the isolation voltage and current measurement module 3, the LED lamp strip 1 and the LED lamp strip 2, a tester can realize human eye observation by observing brightness changes of the LED lamp strip 1 and the LED lamp strip 2; and a numerical value quantification result can be obtained through voltage and current numerical value changes of each node of the isolation voltage and isolation current measurement circuit I, the isolation voltage and isolation current measurement circuit II and the isolation voltage and isolation current measurement circuit III, so that the integration level is relatively high, the workload is reduced, the operation complexity is reduced, and the production and test efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of subway testing equipment, in particular to a PIS screen LED backlight driver testing device. Background Art

[0002] The PIS system, also known as the passenger information system, is a multimedia comprehensive information system that relies on multimedia network technology and takes the computer system as the core. It allows passengers to timely and accurately understand train operation information and public media information through media equipment installed in station halls, platforms, and train passenger compartments. The PIS system is widely used for platform train entry countdown display, train station information in carriages, video media advertising and emergency status information release, including train broadcasts, internal displays, V-screens, carriage monitoring, emergency call equipment, etc.

[0003] At present, 90% of the PIS screens used in subways do not meet the brightness standards, resulting in problems such as low quality of displayed information and poor passenger experience. According to the performance characteristics of the equipment, the key points of screen life and brightness reduction are the aging of the screen backlight tube and the aging of the liquid crystal. To this end, a new type of LED driver backlight was developed based on the PIS screens of Line 1 Phase I, and a batch of new backlight components were produced and tested after installation.

[0004] Using LED backlight driver to replace the original PIS screen's LCD screen's high-voltage light backlight driver has the following advantages. 1. Energy saving: The original device consumes a lot of power. After replacing it with LED backlight, the power consumption is reduced, saving electricity. 2. Extending the life of the equipment: After replacing the backlight component, the service life of the equipment can be extended and the failure rate can be reduced. 3. Improving passenger satisfaction: After the brightness is improved, the passenger information system plays information clearly, enhancing the visual experience of passengers.

[0005] In order to complete the test of LED drivers and ensure the quality of LED drivers after production, a set of LED driver detection devices is designed to realize functional tests such as voltage, current, backlight brightness adjustment, power on / off test of each LED driver, screen and repair those with poor performance, and avoid affecting the use after replacement after installation in PIS screen.

[0006] In the prior art, the conventional method for testing the LED backlight driver of a PIS screen is to use multiple multimeters or voltage and current meters to measure the voltage and current at each measuring point; use a PWM controller to adjust different PWM duty cycles to achieve control and simulation of the backlight brightness; and use a power switch to achieve power on and off testing of the LED driver. The conventional testing method requires wiring and screwing connections at each test point, and manual data recording and observation of test conditions are required during the batch process, which increases the complexity of manual operation, reduces the ease of use of the test process, increases test time and workload, and is not conducive to the efficiency of the test work.

[0007] Since the power input of the LED driver under test is a DC 36V power supply, the LED driver adjusts the brightness according to the power-on / off signal and the PWM control signal. Its working principle is to input a DC voltage and pass it through a dedicated power management chip to achieve a constant current boost, thereby providing a constant current supply to the LED light bar to ensure the brightness of the LED light. In the circuit, since the grounds of the 36V power supply, LED driver, power-on / off signal and PWM control signal are different between different circuits, in order to avoid direct electrical connection of different grounds affecting normal operation, it is necessary to pay special attention to the need for isolated voltage and current measurement of the circuit, and the power-on / off signal and PWM control signal output need to use isolated output. Utility Model Content

[0008] In view of the deficiencies of the prior art, the purpose of the utility model is to provide a PIS screen LED backlight driver testing device, which uses a test fixture to place the LED driver to be tested on the fixture and electrically connects the driver to be tested, avoiding wiring and screw connections, and reducing workload.

[0009] The utility model provides the following technical solutions:

[0010] PIS screen LED backlight driver test device, including:

[0011] An isolation voltage and current measurement module 1, comprising an isolation voltage and current measurement circuit 1, for measuring an input voltage and an input current of a tested LED driver;

[0012] A power on / off test module, comprising a power on / off drive circuit, wherein the power on / off drive circuit is electrically connected to the LED driver under test and is used to test the power on / off function;

[0013] A PWM brightness test module includes a PWM regulation circuit, which is electrically connected to the LED driver under test and is used to test the LED backlight regulation function, and to set different PWM duty cycle values ​​so that the LED driver can achieve different LED backlight brightness adjustments;

[0014] The second isolation voltage and current measurement module includes a second isolation voltage and current measurement circuit, which is used to measure the first LED constant current output of the LED driver under test, and detect and measure the result of the first LED constant current drive;

[0015] The isolation voltage and current measurement module three includes an isolation voltage and current measurement circuit three, which is used to measure the second LED constant current output of the LED driver under test, and detect and measure the result of the second LED constant current drive.

[0016] Preferably, the isolation voltage isolation current measurement circuit 2 is also electrically connected to an LED light strip 1, and the brightness of the LED light strip 1 changes with the change of the LED backlight brightness.

[0017] Preferably, the isolation voltage isolation current measurement circuit three is also electrically connected to the LED light strip two, and the brightness of the LED light strip two changes with the change of the LED backlight brightness.

[0018] Preferably, a test fixture is further included, wherein the test fixture is used to clamp the LED driver to be tested.

[0019] Preferably, it further comprises a human-computer interaction module, wherein the human-computer interaction module comprises a touch screen, and the touch screen is used for display and human-computer interaction of the test device.

[0020] Preferably, it also includes a key switch, and the key switch is used for key switching and control of human-computer interaction.

[0021] Preferably, it also includes a coding switch, and the coding switch is used to adjust the numerical value of the parameter of human-computer interaction.

[0022] Preferably, it also includes a communication module, and the communication module includes a USB interface for connecting to a computer, a tablet or a mobile phone.

[0023] Preferably, the device also includes a power management circuit for managing the power supply inside the test device, for timing power-on of the power supply, and for managing and controlling the power supply of the LED driver under test. When the voltage and current of the LED driver under test are abnormal, the power supply of the part can be automatically cut off to avoid damage to the test device.

[0024] Preferably, it also includes a working status indicator light for indicating the working status of the device.

[0025] Preferably, a buzzer is also included to provide feedback on user operations and test device status indication; when key operations, coding switch operations, touch screen operations, etc. are performed, the buzzer provides user feedback based on human-computer interaction; when an abnormal alarm status indication occurs, the buzzer will sound an alarm.

[0026] The MCU controller is the main control unit and is electrically connected to external devices and circuits.

[0027] Compared with the prior art, the utility model has the following beneficial effects:

[0028] The utility model discloses a PIS screen LED backlight driver testing device, by setting an isolation voltage and current measuring module 1, a PWM brightness testing module, an isolation voltage and current measuring module 2, an isolation voltage and current measuring module 3, and an LED light strip 1 and an LED light strip 2. The tester can realize human eye observation by observing the brightness changes of the LED light strip 1 and the LED light strip 2, and can also obtain numerical quantization results through the voltage and current value changes of each node of the isolation voltage isolation current measuring circuit 1, the isolation voltage isolation current measuring circuit 2, and the isolation voltage isolation current measuring circuit 3. The utility model has a high integration level, reduces the workload, reduces the operation complexity, and improves the production and testing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution of the implementation mode of the utility model, the drawings required for use in the implementation mode are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is the overall circuit block diagram of the utility model.

[0031] Figure 2 This is a circuit diagram of the tested LED driver of the utility model.

[0032] Figure 3 This is a test flow chart of the PIS screen test device of the utility model.

[0033] Figure 4 This is a DC-DC isolation power supply circuit diagram of the utility model.

[0034] Figure 5 This is a circuit diagram of an LDO reference power supply of the utility model.

[0035] Figure 6 The utility model is a minimum system circuit diagram of the STC single chip microcomputer.

[0036] Figure 7 This is a display circuit diagram of the IIC interface of the utility model.

[0037] Figure 8 This is a voltage measurement circuit diagram of the utility model.

[0038] Fig. 9 This is a current measurement circuit diagram of the utility model.

[0039] Fig.10 The utility model discloses a serial port isolation communication circuit.

[0040] Fig.11 This is a circuit diagram of the switch drive circuit of the utility model.

[0041] Fig.12 This is a PWM backlight driving circuit diagram of the utility model. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the implementation of the utility model clearer, the technical solution in the implementation of the utility model will be clearly and completely described below in conjunction with the drawings in the implementation of the utility model. Obviously, the described implementation is only a part of the implementation of the utility model, not all of the implementations. Based on the implementation of the utility model, all other implementations obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0043] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] See also Figure 1-12 As shown, the PIS screen LED backlight driver test device includes:

[0045] An isolation voltage and current measurement module 1, comprising an isolation voltage and current measurement circuit 1, for measuring an input voltage and an input current of a tested LED driver;

[0046] A power on / off test module, comprising a power on / off drive circuit, wherein the power on / off drive circuit is electrically connected to the LED driver under test and is used to test the power on / off function;

[0047] A PWM brightness test module includes a PWM regulation circuit, which is electrically connected to the LED driver under test and is used to test the LED backlight regulation function, and to set different PWM duty cycle values ​​so that the LED driver can achieve different LED backlight brightness adjustments;

[0048] The second isolation voltage and current measurement module includes a second isolation voltage and current measurement circuit, which is used to measure the first LED constant current output of the LED driver under test, and detect and measure the result of the first LED constant current drive;

[0049] The isolation voltage and current measurement module three includes an isolation voltage and current measurement circuit three, which is used to measure the second LED constant current output of the LED driver under test, and detect and measure the result of the second LED constant current drive.

[0050] The isolation voltage isolation current measurement circuit 2 is also electrically connected to an LED light strip 1, and the brightness of the LED light strip 1 changes with the change of the LED backlight brightness.

[0051] The isolation voltage isolation current measurement circuit three is also electrically connected to the LED light strip two, and the brightness of the LED light strip two changes with the change of the LED backlight brightness.

[0052] like Figure 2 As shown, the power supply provides power to the LED driver under test.

[0053] The isolated voltage and isolated current measurement circuit 1 is used to measure the input voltage and input current of the LED driver under test. The use of isolated voltage and isolated current measurement circuits can realize isolated measurement of voltage and current, avoid affecting the operation of the LED driver under test, and ensure the accuracy of the measurement results. The isolated voltage and isolated current measurement circuit 2 is electrically connected to the LED light strip 1, and is used to measure the LED constant current output of the first channel of the LED driver under test, and detect and measure the result of the first channel LED constant current drive. The isolated voltage and isolated current measurement circuit 3 is electrically connected to the LED light strip 2, and is used to measure the LED constant current output of the second channel of the LED driver under test, and detect and measure the result of the second channel LED constant current drive.

[0054] The on / off drive circuit is electrically connected to the LED driver under test to test the on / off function. The PWM adjustment circuit is electrically connected to the LED driver under test to test the LED backlight adjustment function. By setting different PWM duty cycle values, the LED driver can adjust different LED backlight brightness.

[0055] Human eye observation is achieved by observing the brightness changes of LED light bar 1 and LED light bar 2. Numerical quantification results can also be obtained by the voltage and current value changes of each node of the isolation voltage isolation current measurement circuit 1, the isolation voltage isolation current measurement circuit 2, and the isolation voltage isolation current measurement circuit 3.

[0056] like Figure 1As shown, the MCU controller is the main control unit, which is electrically connected to the external device and circuit respectively. The touch screen is used for the display and human-computer interaction of the test device. The test device can be used and operated through the touch screen without connecting to a computer. The buzzer realizes the feedback of user operation and the status indication of the test device. When key operation, coding switch operation, touch screen operation, etc. are performed, the buzzer is based on the user feedback of the human-computer interaction. When an abnormal alarm or other status indication occurs, the buzzer will alarm. The working status indicator light is used to indicate the working status of the device. The isolation voltage isolation current measurement circuit 1, the isolation voltage and isolation current measurement circuit 2, and the isolation voltage and isolation current measurement circuit 3 are respectively used to measure the input voltage and input current of the tested LED driver; used to measure the LED constant current output of the first channel of the tested LED driver, detect and measure the result of the first channel LED constant current drive; used to measure the LED constant current output of the second channel of the tested LED driver, detect and measure the result of the second channel LED constant current drive. The USB interface realizes the connection with the computer and other devices, realizes the communication between the test device and the computer, and realizes the data upload and data storage of the measured data, data display and test result display, etc. The power management circuit manages the internal power supply of the test device, realizes the timed power-on of the power supply, and realizes the power supply management and control of the LED driver under test. When the voltage and current of the LED driver under test are abnormal, the power supply of this part can be automatically cut off to avoid damage to the test device. The key switch realizes the key switching and control of human-computer interaction. The coding switch realizes the rotation adjustment of the parameter value and other operations of human-computer interaction, has good human-computer interaction, and is convenient for adjusting parameters. The power on and off drive circuit can output a level signal that matches the level of the LED driver under test, such as 3.3V for power on and 0V for power off. It is used to test the power on and off function of the LED driver under test. The PWM adjustment circuit can set different PWM duty cycle values, which is used to test the LED backlight adjustment function of the LED driver under test, and can adjust the brightness of different LED backlights.

[0057] like Figure 3As shown, it is a test flow chart of the PIS screen test device. After the test starts, the MCU control unit of the test device controls the power management circuit to turn on the test power supply, set it to the initial PWM value, set the power on / off function to the power on state, and the current measurement circuit 1, the isolation voltage and isolation current measurement circuit 2, and the isolation voltage and isolation current measurement circuit 3 detect the values ​​of each test point to judge whether the LED driver under test is normal. If the function of the LED driver under test is abnormal, a fault alarm is given, the test result is displayed, and the test is stopped. If the function of the LED driver under test is normal, the power on / off function and PWM brightness test are performed, and the power on / off function and different PWM brightness value tests are automatically performed. Through the current measurement circuit 1, the isolation voltage and isolation current measurement circuit 2, and the isolation voltage and isolation current measurement circuit 3, the values ​​of each test point are detected to judge whether the LED driver under test meets the test requirements. If the test requirements are not met, a fault alarm is given, the test results are displayed, and the test is stopped. If the test requirements are met, the test results are displayed and the test is stopped.

[0058] Take the isolation voltage isolation current measurement circuit 1 as an example:

[0059] like Figure 4 The DC-DC isolated power supply circuit is shown in the figure. The DC-DC isolated power supply circuit in the isolated voltage and isolated current measurement circuit is used to generate an isolated 5V DC voltage to power the isolated voltage and isolated current measurement circuits.

[0060] like Figure 5 The figure shows the LDO reference power circuit diagram. It is used to convert the input 5V voltage into a high-precision reference voltage 3.3V output using the TL431 high-precision voltage reference and the LDO adjustable voltage composed of the NMOS tube, and provide a reference voltage for the MCU and measurement circuit of the isolation voltage and isolation current measurement circuit.

[0061] like Figure 6 The figure shows the minimum system circuit diagram of the STC microcontroller. As the main control MCU, it can measure the voltage and current signals of the isolation voltage and isolation current measurement circuit, drive the display screen, and perform serial communication.

[0062] like Figure 7 The figure shows the display circuit diagram of the IIC interface, which realizes the functions of parameter display, etc.

[0063] like Figure 8 The voltage measurement circuit diagram is shown in Figure 1. The voltage to be measured is electrically connected, and after being stepped down by the resistor network, it becomes a voltage signal that can be detected by the MCU. After analog-to-digital conversion by the ADC inside the MCU, the measured voltage value can be obtained through parameter conversion.

[0064] like Fig. 9As shown in the figure, the current measurement circuit diagram is shown. The current to be measured is electrically connected, and the current sampling resistor is connected in series to the circuit to be measured. The current signal generates a voltage signal through the current sampling resistor. After the voltage signal is amplified by the in-phase ratio of the operational amplifier, the voltage signal is amplified, and after the ADC analog-to-digital conversion inside the MCU, the measured current value can be obtained through parameter conversion.

[0065] like Fig.10 The figure shows a serial port isolation communication circuit. The isolation voltage and isolation current measurement circuits realize isolated communication with other circuits through serial port communication isolated by optical coupler.

[0066] like Fig.11 As shown, it is the circuit diagram of the power-on / off drive circuit. This circuit is a power-on / off drive circuit, and the power supply of this circuit is an isolated power supply. P1.0 is the IO port of the MCU that outputs high and low levels, thereby realizing the power-on or power-off function control. Q5 is an NMOS tube, R68 is the pull-down resistor of the MOS tube gate, R66 is the IO port of the microcontroller P1.0 and the gate resistor of the NMOS in series, R62 is the pull-up resistor of the signal output, and P7 is the output interface. When P1.0 is at a high level, the NMOS tube is turned on, and P7 outputs a low level. When P1.0 is at a low level, the NMOS tube is not turned on, and P7 outputs a high level.

[0067] like Fig.12 As shown in the figure, it is a PWM backlight driving circuit diagram. This circuit is a PWM regulation circuit, and the power supply of this circuit is an isolated power supply. P1.1 is the IO port of the MCU, which outputs PWM signals with different duty cycles, thereby realizing the adjustment function control of the PWM backlight brightness. Q6 is an NMOS tube, R69 is the pull-down resistor of the MOS tube gate, R67 is the gate resistor connected in series with the IO port of the microcontroller P1.0 and the NMOS, R63 is the pull-up resistor of the signal output, and P8 is the output interface.

[0068] When P1.1 is high, the NMOS tube is turned on and P8 outputs a low level. When P1.1 is low, the NMOS tube is not turned on and P8 outputs a high level. When P1.1 outputs PWM signals with different pulse widths, P8 outputs signals with different PWM duty cycles.

[0069] The invention also includes a test fixture, which is used to clamp the LED driver to be tested. The fixture is a prior art and adopts a universal fixture for driver testing disclosed in application number CN201921361865.5.

[0070] The above is only a preferred implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes within the technical scope disclosed by the present invention according to the technical solution and inventive concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. PIS screen LED backlight driver test device, characterized by: include: An isolation voltage and current measurement module 1, comprising an isolation voltage and current measurement circuit 1, for measuring an input voltage and an input current of a tested LED driver; A power on / off test module, comprising a power on / off drive circuit, wherein the power on / off drive circuit is electrically connected to the LED driver under test and is used to test the power on / off function; A PWM brightness test module includes a PWM regulation circuit, which is electrically connected to the LED driver under test and is used to test the LED backlight regulation function, and to set different PWM duty cycle values ​​so that the LED driver can achieve different LED backlight brightness adjustments; The second isolation voltage and current measurement module includes a second isolation voltage and current measurement circuit, which is used to measure the first LED constant current output of the LED driver under test, and detect and measure the result of the first LED constant current drive; The isolation voltage and current measurement module three includes an isolation voltage and current measurement circuit three, which is used to measure the second LED constant current output of the LED driver under test, and detect and measure the result of the second LED constant current drive.

2. The PIS screen LED backlight driver testing device according to claim 1, characterized in that: The isolation voltage isolation current measurement circuit 2 is also electrically connected to an LED light strip 1, and the brightness of the LED light strip 1 changes with the change of the LED backlight brightness.

3. The PIS screen LED backlight driver testing device according to claim 1, characterized in that: The isolation voltage isolation current measurement circuit three is also electrically connected to the LED light strip two, and the brightness of the LED light strip two changes with the change of the LED backlight brightness.

4. The PIS screen LED backlight driver testing device according to claim 1, characterized in that: Also included is a test fixture, which is used to clamp the LED driver under test.

5. The PIS screen LED backlight driver testing device according to claim 1, characterized in that: It also includes a human-computer interaction module, which includes a touch display screen, and the touch display screen is used for display and human-computer interaction of the test device.

6. The PIS screen LED backlight driver testing device according to claim 5, characterized in that: It also includes a key switch, which is used for key switching and control of human-computer interaction.

7. The PIS screen LED backlight driver testing device according to claim 6, characterized in that: It also includes a coding switch, which is used to adjust the numerical value of the parameter of human-computer interaction.

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