A measuring module and an LED dimming circuit using the same

Abstract

The application relates to a measuring module and an LED dimming circuit using the same. The measuring module is electrically connected with a PWM signal generating module and a driving device module. The measuring module is used for detecting a PWM signal and a driving device pass signal. The measuring module comprises a measuring processor, a first measuring capacitor and a second measuring capacitor. The first measuring capacitor is arranged at a signal output end of the PWM signal, and the signal output end is located between electrode plates of the first measuring capacitor. The second measuring capacitor is arranged at a controlled output end of the driving device, and the controlled output end is located between electrode plates of the second measuring capacitor. The electrode plates with the same polarity are electrically connected. The electrode plate with the positive polarity is electrically connected with the measuring processor and outputs a measuring signal. The electrode plate with the negative polarity is grounded. The measuring processor receives the measuring signal, compares the measuring signal with a built-in reference signal, and outputs a measuring result. The application has the effects of reducing the hardware resource demand and improving the measuring stability.

Description

Technical Field

[0001] This application relates to the field of LED drivers, and more particularly to a measurement module and an LED dimming circuit using the measurement module. Background Technology

[0002] LEDs are low-voltage driven constant-current driven devices. Due to the limitations of LED power levels, multiple LEDs typically need to be driven simultaneously to meet brightness requirements. Therefore, specialized [devices / mechanisms] are required. drive circuit Let's turn on the LEDs. Different types of LED lights require different... power adapter .

[0003] Existing dimming methods include PWM dimming, also known as pulse width modulation, where the signal generator uses simple digital pulses to repeatedly switch... LED driver The system only needs to provide digital pulses of varying widths to easily change the output current, thereby adjusting the LED brightness. PWM dimming can provide high-quality white light, is simple to apply, and is highly efficient.

[0004] When using PWM dimming, in order to detect the parameters of the dimming process, it is necessary to measure the response status of the PWM and the driving device. Therefore, two measurement branches are required: one measurement branch measures the PWM, and the other measurement branch measures the driving device. The measurement results of the PWM and the driving device are then compared and calculated to obtain the dimming control result. However, this measurement method requires two measurement branches, which consumes a lot of hardware resources. Summary of the Invention

[0005] To simplify existing measurement methods and reduce the hardware resources occupied by measurement circuits, this application provides a measurement module and an LED dimming circuit using the measurement module.

[0006] Firstly, this application provides a measurement module, which adopts the following technical solution:

[0007] A measurement module is electrically connected to both a PWM signal generation module and a driving device module. The PWM signal generation module generates a PWM signal, and the driving device module supplies power in response to the PWM signal. The signal generated by the driving device module is in phase and frequency with the PWM signal but has a different amplitude. The measurement module is used to detect the path signal between the PWM signal and the driving device.

[0008] The measurement module includes a measurement processor, a first measurement capacitor, and a second measurement capacitor. The first measurement capacitor is disposed at the signal output terminal of the PWM signal, and the lead of the signal output terminal is located between the two electrode plates of the first measurement capacitor. The second measurement capacitor is disposed at the controlled output terminal of the driving device, and the lead of the controlled output terminal is located between the two electrode plates of the second measurement capacitor. The electrode plates of the first and second measurement capacitors with the same polarity are electrically connected, wherein the positive electrode plate is electrically connected to the measurement processor and outputs a measurement signal, and the negative electrode plate is grounded. The measurement processor receives the measurement signal, compares the measurement signal with a built-in reference signal, and outputs the measurement result.

[0009] By adopting the above technical solution, two measuring capacitors are used as measuring probes. The two electrode plates of the measuring capacitors are located on both sides of the corresponding leads, which can sense the changes in the signal on the leads. When there is no signal on the lead, no induced signal is generated on the electrode plates. When the lead maintains a high-level signal, no dynamic induced signal is generated on the electrode plates. When the signal on the lead changes, a dynamic induced signal is generated on the electrode plates, which can be detected and compared by the measurement processor, and finally the measurement result is output. Each measuring capacitor measures a corresponding terminal, and the two capacitors are connected in parallel, which allows the measurement processor to simultaneously detect whether the corresponding terminals are working properly, reducing hardware resource requirements. In addition, when the driving force of the PWM signal decreases and may cause measurement fluctuations, the second measuring capacitor at the controlled output terminal can transfer the induced charge to the first measuring capacitor, improving measurement stability. When the driving capability of the PWM signal is insufficient, when the second measuring capacitor inputs electrical energy to the first measuring capacitor, the electrode plates of the first measuring capacitor make the potential at the signal output terminal more stable, with higher driving capability.

[0010] Preferably, the electrode plates are all flat, and the lead wires of the signal output terminal and the lead wires of the controlled output terminal are integrally provided with a drain plate, which is arranged parallel to the electrode plates.

[0011] By adopting the above technical solution, the current-draining plate and the electrode plate are arranged in parallel, and both have a larger sensing area, which can improve the sensitivity to respond to changes in charge and improve the stability of the measurement results.

[0012] Preferably, the lead wire is cylindrical, and the electrode plate is arc-shaped and attached to one side of the arc-shaped lead wire.

[0013] By adopting the above technical solution, the arc-shaped electrode plate is adapted to the surface of the lead wire. When there is a high-frequency PWM signal on the lead wire, for DC, the current is distributed across the entire cross-section of the conductor. However, at high frequencies, the current distribution becomes uneven, and most of the current is concentrated near the surface of the conductor. Therefore, the arc-shaped electrode plate can improve the measurement response sensitivity.

[0014] Preferably, the lead of the signal output terminal and the lead of the controlled output terminal are integrally provided with a guide plate, and the guide plate is located in the gap between adjacent electrode plates.

[0015] By adopting the above technical solution, the drain plate is located between the opposing arc-shaped electrode plates and separates the two opposing arc-shaped electrode plates, thereby increasing the induction intensity of the lead wire to the electrode plate.

[0016] Preferably, the side of the drainage plate is rolled up to cover the electrode plate electrically connected to the measurement processor.

[0017] By adopting the above technical solution, the induction intensity of the lead wire to the electrode plate is improved, and the induction force between the two electrode plates can be reduced when the potential on the lead wire changes.

[0018] Preferably, the electrode plate has an arc-shaped groove in the middle, and the lead wire passes through the arc-shaped hole formed by the arc-shaped groove on the adjacent electrode plate.

[0019] By adopting the above technical solution, the induction intensity of the lead wire to the electrode plate is further improved, and the measurement response sensitivity is enhanced.

[0020] Preferably, the measurement processor receiving the measurement signal further includes:

[0021] The measurement processor detects the number of level changes of the measurement signal during the period of the PWM signal. If the number of level changes is four, a normal signal is output; otherwise, an abnormal signal is output.

[0022] By adopting the above technical solution, during the period of the PWM signal, when the PWM signal changes twice, the voltage on the first measuring capacitor also changes twice, the driving device operates twice, the voltage on the second measuring capacitor also changes twice, and the time is delayed compared to the first measuring capacitor. The signal transmitted to the measurement processor changes four times.

[0023] Preferably, the comparison between the measured signal and the built-in reference signal further includes:

[0024] If a normal signal is output for a set number of consecutive cycles, the PWM frequency is increased; otherwise, the PWM frequency is maintained or decreased.

[0025] By adopting the above technical solution, the driving module can be assisted in adjusting the frequency. The higher the frequency, the better the controlled lighting effect.

[0026] Secondly, this application provides an LED dimming circuit, which adopts the following technical solution:

[0027] An LED dimming circuit includes a PWM signal generating module, a signal conversion module, a driving device module, and an LED module connected in sequence. The PWM signal generating module is electrically connected to any of the above-mentioned measurement modules, and the measurement module is also electrically connected to the driving device module.

[0028] The PWM signal generation module generates a corresponding PWM signal in response to the received dimming signal, the signal conversion module generates a drive signal in response to the PWM signal, the drive signal and the PWM signal are in phase and have the same frequency but different amplitudes, the drive device module supplies power to the LED module in response to the drive signal, and the measurement module detects the path signal between the PWM signal and the drive device, compares the difference between the PWM signal and the path signal, and outputs the measurement result.

[0029] By adopting the above technical solution, after the LED dimming circuit is equipped with a measurement module, two measurement capacitors are used as measurement probes. Each measurement capacitor measures a corresponding terminal. The parallel connection of the two capacitors allows the measurement processor to simultaneously detect whether the corresponding terminals are working properly, reducing hardware resource requirements. When the PWM signal driving capability is insufficient, when the second measurement capacitor inputs electrical energy to the first measurement capacitor, the electrode plate of the first measurement capacitor makes the potential of the signal output terminal more stable, thus having a higher driving capability.

[0030] This application has at least the following beneficial effects:

[0031] (1) The measurement module uses phase-to-phase connection between the first and second measurement capacitors, which only requires one measurement port of a measurement processor to measure the two signals, thus reducing the hardware resource requirements;

[0032] (2) When the driving force of the PWM signal decreases and may cause measurement fluctuations, the second measurement capacitor at the controlled output terminal can transfer the induced charge to the first measurement capacitor to improve measurement stability.

[0033] (3) When the PWM signal driving capability is insufficient, the second measuring capacitor can input electrical energy to the first measuring capacitor, making the potential at the signal output terminal more stable and having a higher driving capability. Attached Figure Description

[0034] Figure 1 This is a schematic block diagram of the LED dimming circuit of this application;

[0035] Figure 2 This is an enlarged schematic diagram of the flat electrode plate structure in the measurement module;

[0036] Figure 3 This is a schematic diagram of the vertical cross-section of the electrode plate in the measurement module, which is arc-shaped and located in the axial direction.

[0037] Figure 4 This is a schematic diagram of charge movement when the PWM signal is high in the measurement module;

[0038] Figure 5 This is a schematic diagram of charge movement when the PWM signal in the measurement module is at a low level.

[0039] Reference numerals: 1. PWM signal generation module; 2. Signal conversion module; 3. Driver module; 4. LED module; 5. Measurement module; 51. Measurement processor; 52. First measurement capacitor; 53. Second measurement capacitor; 6. Drain plate. Detailed Implementation

[0040] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0041] The embodiments of this application will now be described in further detail with reference to the accompanying drawings.

[0042] This application discloses a measurement module, such as... Figure 1 As shown, both the PWM signal generation module 1 and the driving device module 3 are electrically connected. The PWM signal generation module 1 can use a dedicated PWM chip or an existing PWM generation module in a microcontroller. The corresponding PWM signal can be output by writing to the PWM-corresponding register. The PWM signal generation module 1 is electrically connected to a signal conversion module 2, which amplifies the level of the PWM signal. For example, if the highest level of the PWM signal is 3V, the signal conversion module can amplify the highest level to 12V or 24V. The signal conversion module can use power transistors, MOSFETs, or integrated driver chips with in-phase input and output. The signal conversion module converts the PWM signal into a driving signal and sends the driving signal to the driving device module 3. The driving device module 3 responds to the PWM signal to power the LED module. The signal generated by the driving device module 3 is in phase and frequency with the PWM signal but has a different amplitude. The driving device module 3 includes multiple power devices, which can form a half-bridge or full-bridge to provide the required current to the LED module 4.

[0043] Measurement module 5 is used to detect the PWM signal and the path signal of the driving device. The PWM signal and the path signal are in phase and have the same frequency, but different amplitudes. Measurement module 5 includes a measurement processor 51, a first measurement capacitor 52, and a second measurement capacitor 53. The measurement processor 51 can be a microcontroller, and the PWM signal generation module 1 can be a PWM generation module in the microcontroller. The microcontroller can be a Freescale K60 microcontroller, and the PWM generation module can be the PIT module in the K60 microcontroller. The first measurement capacitor 52 and the second measurement capacitor 53 are self-made capacitors, not purchased finished electronic components. The PWM signal generation module 1, the signal conversion module 2, the driving device module 3, and the LED module 4 can be electrically connected using integrated circuit boards, or using cylindrical wires or hollow wires.

[0044] The first measuring capacitor 52 is located at the signal output terminal of the PWM signal, and the lead of the signal output terminal is located between the two electrode plates of the first measuring capacitor 52. The second measuring capacitor 53 is located at the controlled output terminal of the driving device, and the lead of the controlled output terminal is located between the two electrode plates of the second measuring capacitor 53. If the circuit uses a PCB, it is a PCB with at least three layers, preferably a four-layer PCB. In this case, the lead is located on the middle layer of the PCB, and the electrode plate is located on the upper or lower layer of the lead, and is a large copper-clad sheet. The electrode plates of the first measuring capacitor 52 and the second measuring capacitor 53 with the same polarity are electrically connected, and are also electrically connected to the detection terminal of the measurement processor 51. The detection terminal of the measurement processor 51 indirectly measures the current through a resistor. The positive electrode plate is electrically connected to the measurement processor 51 and outputs a measurement signal, while the negative electrode plate is grounded. The first measuring capacitor 52 and the second measuring capacitor 53 can be pre-charged. When there is no signal, there is no change in charge in the fully charged first measuring capacitor 52 and the second measuring capacitor 53, and the detection terminal does not detect any change in current. When the PWM signal is generated normally, a change in charge occurs on the lead wire, and the charge in the first measuring capacitor 52 and the second measuring capacitor 53 also changes and moves, which can be measured.

[0045] On the PCB, the measurement processor 51 receives the measurement signal. Within one cycle T of the PWM signal, the measurement processor 51 detects the number of level changes in the measurement signal. Normally, the PWM signal changes twice within one cycle T, representing the rising and falling edges of a pulse. The response signal also changes twice, also representing the rising and falling edges of a pulse. Therefore, if the level changes four times, a normal signal is output; otherwise, an abnormal signal is output. Within one cycle of the PWM signal, when the PWM signal changes twice, the voltage on the first measuring capacitor 52 also changes twice, driving the device twice. The voltage on the second measuring capacitor 53 also changes twice, with a time delay compared to the first measuring capacitor 52. Therefore, the signal transmitted to the measurement processor 51 changes four times.

[0046] The measurement processor 51 compares the measured signal with a built-in reference signal and outputs the measurement result. The reference signal can be the number of level changes and the time difference between two adjacent level changes. If the number of level changes is insufficient or the time difference is too long, the output measurement result indicates a circuit fault; otherwise, the output measurement result indicates a normal circuit. To use the measured data as feedback to achieve negative feedback, if a normal signal is output for a set number of consecutive cycles, the PWM frequency is increased; otherwise, the PWM frequency is maintained or decreased. This assists the drive module in adjusting the frequency; a higher frequency results in better controlled lighting effects.

[0047] To increase the driving current and thus the driving power, the circuit may not be entirely based on a PCB. In this case, the electrode plates are all flat, and to increase the sensing area, such as... Figure 2 As shown, the lead wires at the signal output terminal and the lead wires at the controlled output terminal are integrally equipped with a current-guiding plate 6. A special terminal with the current-guiding plate 6 can be used as the lead wire terminal, or the current-guiding plate 6 can be soldered onto the lead wires after the insulation has been stripped. Then, the current-guiding plate 6 is arranged parallel to the electrode plate. After the current-guiding plate 6 and the electrode plate are arranged parallel, both have a larger sensing area, which can improve the sensitivity to changes in charge.

[0048] In another case, such as Figure 3 As shown, another type of wire can be selected as the lead wire. The lead wire is cylindrical, and correspondingly, the electrode plate is also adapted to be arc-shaped and attached to one side of the arc-shaped lead wire. An insulating layer, insulating paper, or gap layer is provided in the middle, so that an arc-shaped groove is formed in the middle of the electrode plate. The lead wire passes through the arc-shaped hole formed by the opposing arc-shaped grooves on the adjacent electrode plates. Similarly, the lead wire at the signal output end and the lead wire at the controlled output end are also provided with a drain plate 6. The drain plate 6 can be arranged in a similar manner to the previous case, and the drain plate 6 is located in the gap between adjacent electrode plates. Furthermore, the side of the drain plate 6 can be rolled up to cover the electrode plate electrically connected to the measurement processor 51. The drain plate 6 is located between the opposing arc-shaped electrode plates and separates the two opposing arc-shaped electrode plates, which can increase the induction intensity of the lead wire to the electrode plate and reduce the induction force between the two opposing electrode plates when the potential on the lead wire changes. This increases the induction intensity of the lead wire to the electrode plate. The lead wire is located in the channel formed by two opposing arc-shaped grooves. When there is a high-frequency PWM signal on the lead wire, the current is distributed across the entire cross-section of the conductor for DC. However, at high frequencies, the current distribution becomes uneven, and most of the current is concentrated near the surface of the conductor. Therefore, the arc-shaped electrode plate can improve the measurement response sensitivity.

[0049] Back Figure 1Measurement module 5 uses two measuring capacitors as measuring probes, eliminating the need for two separate measurement modules 5. Each measuring capacitor has two electrode plates located on opposite sides of a corresponding lead. When a pulse signal is present on the lead, the positive electrode plate can sense the signal change. When the lead maintains a low-level signal, no induced signal is generated on the electrode plate; similarly, when the lead maintains a high-level signal, no dynamic induced signal is generated. However, when the level signal on the lead changes, a dynamic induced signal is generated on the electrode plate, which can be detected and compared by the measurement processor 51, ultimately outputting the measurement result. Each measuring capacitor measures one corresponding terminal, and the parallel connection of two capacitors allows the measurement processor 51 to simultaneously detect whether the corresponding terminals are functioning correctly, reducing hardware resource requirements.

[0050] The positive electrode plates of the first measuring capacitor 52 and the second measuring capacitor 53 are electrically connected. When the lead of the output PWM signal goes high, such as Figure 4 As shown, if the driving force of the lead decreases, it may lead to driving instability or fluctuations in the measurement signal. When the lead output at the controlled output terminal becomes high, the voltage in the second measuring capacitor 53 can be raised, the charge in the second measuring capacitor 53 can be transferred to the first measuring capacitor 52, and the charge induced in the second measuring capacitor 53 can also be transferred to the first measuring capacitor 52. When the voltage of the positive electrode plate of the first measuring capacitor 52 rises, some electrons can be extracted from the terminal of the signal conversion module 2, thereby improving the current driving capability. When the lead outputting the PWM signal becomes low, such as Figure 5 As shown, when the lead output at the controlled output terminal becomes low, the voltage in the second measuring capacitor 53 can be pulled down, and the charge in the first measuring capacitor 52 can be transferred to the second measuring capacitor 53. When the voltage of the positive electrode plate of the first measuring capacitor 52 drops, the low-level stability of the wire can be improved, thus enhancing the driving stability.

[0051] This application also discloses an LED dimming circuit, such as... Figure 1 As shown, it has any of the above-mentioned measurement modules 5 built in.

[0052] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A measurement module electrically connected to a PWM signal generation module (1) and a driving device module (3), wherein the PWM signal generation module (1) generates a PWM signal, the driving device module (3) is powered in response to the PWM signal, and the signal generated by the driving device module (3) is in phase and frequency with the PWM signal but has a different amplitude, characterized in that: The measurement module (5) is used to detect the path signal between the PWM signal and the driving device; The measurement module (5) includes a measurement processor (51), a first measurement capacitor (52), and a second measurement capacitor (53). The first measurement capacitor (52) is disposed at the signal output terminal of the PWM signal, and the lead of the signal output terminal is located between the two electrode plates of the first measurement capacitor (52). The second measurement capacitor (53) is disposed at the controlled output terminal of the driving device, and the lead of the controlled output terminal is located between the two electrode plates of the second measurement capacitor (53). The electrode plates of the first measurement capacitor (52) and the second measurement capacitor (53) of the same polarity are electrically connected. The positive electrode plate is electrically connected to the measurement processor (51) and outputs a measurement signal, while the negative electrode plate is grounded. The measurement processor (51) receives the measurement signal, compares the measurement signal with a built-in reference signal, and outputs the measurement result. The first measuring capacitor (52) and the second measuring capacitor (53) are electrically connected to the same polarity of the electrode plates and are electrically connected to the detection terminal of the measuring processor (51). The detection terminal of the measuring processor (51) indirectly measures the current through a resistor. The measuring processor (51) detects the number of level changes of the measuring signal in one cycle T of the PWM signal. The reference signal is the number of level changes or the time difference between two adjacent level changes. The measuring processor (51) compares the measuring signal with the built-in reference signal and outputs the measurement result. If the number of level changes is not up to standard or the time difference is too long and not up to standard, the output measurement result is a circuit fault. Otherwise, the output measurement result is a normal circuit.

2. The measurement module according to claim 1, characterized in that: All electrode plates are flat. The lead wires of the signal output terminal and the lead wires of the controlled output terminal are integrally provided with a drain plate (6). The drain plate (6) is arranged parallel to the electrode plate.

3. The measurement module according to claim 1, characterized in that: The lead wire is cylindrical, and the electrode plate is arc-shaped and attached to one side of the arc-shaped lead wire.

4. The measurement module according to claim 2, characterized in that: The lead wire of the signal output terminal and the lead wire of the controlled output terminal are integrally provided with a guide plate (6), and the guide plate (6) is located in the gap between adjacent electrode plates.

5. The measurement module according to claim 4, characterized in that: The side of the drain plate (6) is rolled up to cover the electrode plate that is electrically connected to the measurement processor (51).

6. The measurement module according to claim 3, characterized in that: An arc-shaped groove is provided in the middle of the electrode plate, and the lead wire passes through the arc-shaped hole formed by the opposite arc-shaped groove on the adjacent electrode plates.

7. The measurement module according to claim 1, characterized in that: The measurement processor (51) receiving the measurement signal further includes: The measurement processor (51) detects the number of level changes of the measurement signal during the period of the PWM signal. If the number of level changes is four, it outputs a normal signal; otherwise, it outputs an abnormal signal.

8. The measurement module according to claim 7, characterized in that: The comparison between the measured signal and the built-in reference signal also includes: If a normal signal is output for a set number of consecutive cycles, the PWM frequency is increased; otherwise, the PWM frequency is maintained or decreased.

9. An LED dimming circuit, characterized in that: The system includes a PWM signal generating module (1), a signal conversion module (2), a driving device module (3), and an LED module (4) connected in sequence. The PWM signal generating module (1) is electrically connected to a measurement module as described in any one of claims 1-8. The measurement module (5) is also electrically connected to the driving device module (3). The PWM signal generation module (1) generates a corresponding PWM signal in response to the received dimming signal. The signal conversion module (2) generates a drive signal in response to the PWM signal. The drive signal is in phase and frequency with the PWM signal but has a different amplitude. The drive device module (3) supplies power to the LED module (4) in response to the drive signal. The measurement module (5) detects the path signal between the PWM signal and the drive device, compares the difference between the PWM signal and the path signal, and outputs the measurement result.

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