Dimming device and LED driver device with a dimming device

Abstract

A dimming device, characterized in that the dimming device comprises: a dimmer (101) wherein the dimmer (101) comprises a resistor component with an adjustable resistance value; an impedance-frequency converter network (102) connected to the resistance component to convert the resistance value of the dimmer (101) into a frequency signal, where different resistance values ​​correspond to frequency signals with different frequencies; a controller (103) connected to the impedance-frequency converter network (102) to receive the frequency signal from the impedance-frequency converter network (102), to identify the frequency from the frequency signal and to control the output current of an LED driver (20) connected to the controller (103) based on the identified frequency, the impedance-frequency converter network (102) comprises: an optocoupler (1022) wherein the impedance frequency converter network (102) is connected to the controller (103) via the optocoupler (1022) in order to transmit the frequency signal of the impedance frequency converter network (102) in isolation to the controller (103).

Description

Technical field

[0001] The present disclosure relates to the field of electronics, in particular circuit design, and more specifically to a dimming device and an LED driver device comprising a dimming device. background

[0002] In LED lighting systems, galvanic isolation between the dimmer and the LED driver is a crucial aspect, as it affects not only product safety but also the precision and reliability of the dimming process. Conventional isolation methods typically use an optocoupler, a component that transmits electrical signals via light to achieve electrical isolation. An optocoupler consists of a light transmitter (such as an LED) and a light receiver (such as a phototransistor) housed in an opaque enclosure to ensure electrical isolation.

[0003] In practice, as inFig. As shown in Figure 6, a dimmer can comprise multiple DIP switches S1-SN, with each switch representing a different brightness setting. To achieve dimming, the signal from each DIP switch must be transmitted to the LED driver. In a conventional design, each DIP switch requires a separate optocoupler for signal transmission. Therefore, each DIP switch is equipped with a corresponding optocoupler (6001-600N in [reference missing]). Fig. 6) connected. These signals are then received by the sampling terminals ADC1-ADCN of an analog-to-digital converter (ADC) of the controller 603, and the controller 603 controls the LED driver based on these signals to adjust the brightness of the LED.

[0004] However, this method has some limitations. First, using multiple optocouplers increases cost and complexity, as each DIP switch requires its own optocoupler. Second, the need for multiple optocouplers increases the required printed circuit board (PCB) area. Furthermore, the requirement to provide multiple ADC sampling connections on the controller occupies many of the controller's pins. Task

[0005] Therefore, there is a need to develop a dimming device that enables isolated dimming while simultaneously reducing the cost of this dimming device, minimizing its PCB layout area, and reducing the number of pins used on the controller. Description of the invention

[0006] To overcome the aforementioned disadvantages of the prior art, the present disclosure provides a solution for the isolated dimming of an LED driver which uses only an optocoupler, a control connection and a series and parallel circuit structure of switches and resistors or a sliding resistor, thereby solving the aforementioned technical problems.

[0007] To achieve the aforementioned goal, the present disclosure is realized through the following technical solution: According to one aspect of the present disclosure, a dimming device is provided which includes: a dimmer with a resistor component with an adjustable resistance value; an impedance-to-frequency converter network that converts the resistance value into a frequency signal; a controller that receives the frequency signal, identifies the frequency, and controls the output current of an LED driver.

[0008] The impedance-frequency converter network includes an optocoupler for isolated transmission of the frequency signal to the control unit.

[0009] In this way, by using a resistor component with an adjustable resistance value as a dimmer, converting different resistance values ​​into different frequencies using the impedance-frequency converter network, and transmitting the frequency signal to the controller via a single optocoupler, a cost-effective solution for isolated dimming is created. Consequently, the present disclosure achieves isolated dimming of an LED driver using only one optocoupler, one controller connection, and a series-parallel circuit structure of switches and resistors or a sliding resistor. • In one embodiment, the resistance component comprises at least two parallel-connected resistance units, each consisting of a switch and a resistor in series. This simplifies the circuit structure of the dimmer. • In one embodiment, the switches are DIP switches, which allows for simple and controllable operation. • In another embodiment, the resistance component is a sliding resistor, which is a simple and effective method for adjusting the resistance. • In one embodiment, the impedance-to-frequency converter network comprises a first and a second RC charge / discharge network. To generate a self-sustaining oscillation for converting the resistance value into a frequency signal, two conditions must be met: 1. Amplitude amplification; 2. a phase shift of 180 degrees.

[0010] The use of two RC networks fulfills these conditions, since a single RC network can only achieve a phase shift of 90 degrees, while two RC networks can achieve a phase shift of 180 degrees. This allows the conversion of the resistance value into a frequency signal with a simple circuit structure. • In one embodiment, the controller includes an edge-trigger circuit that triggers on a signal edge (transition from low to high or high to low). This increases the precision of the timing control and reduces the complexity of the circuit. Detection is strictly dependent on the signal edge, not on the duration of the signal state, which ensures stability and predictability and reduces the risk of false triggering at high speeds. • In another embodiment, the impedance-frequency converter network includes a parallel-connected diode that provides voltage clamping, absorption of voltage spikes and a low-impedance path, increasing the stability of the circuit.

[0011] The present disclosure provides a dimming device and an LED driver device incorporating a dimming device. The dimmer is implemented using a series-parallel circuit structure of DIP switches and resistors or a slide resistor. An impedance-frequency converter network allows different resistance values ​​to be converted into different frequencies and transmitted in isolation via a single optocoupler, forming a cost-effective, isolated dimming structure. This overcomes the technical problems associated with the use of multiple optocouplers, namely high cost, large and complex PCB layout area, and high pin density on the controller. Brief description of the drawings

[0012] The drawings contained herein, which form part of this description, illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure without unduly limiting them. The drawings include: Fig. Figure 1 is a schematic diagram of an LED driver device according to an embodiment of the present disclosure Fig. Figure 2 is a schematic diagram of a first embodiment of the dimming device in the LED driver device. Fig. Figure 3 is a schematic diagram of a second embodiment of the dimming device in the LED driver device. Fig. Figure 4 is a schematic circuit diagram of the impedance-frequency converter network in the dimming device. Fig. Figure 5 is a voltage-time diagram of the sampling by the edge trigger circuit. Fig.Figure 6 is a schematic diagram of a dimming device according to the state of the art. Preferred embodiment of the invention

[0013] To enable those skilled in the art to better understand the technical solutions of this disclosure, the technical solutions in the embodiments of the disclosure are described clearly and completely below with reference to the drawings. It is obvious that the described embodiments represent only a part and not all embodiments of this disclosure. All other embodiments that a person skilled in the art derives from the embodiments described herein without any creative effort fall within the scope of protection of this disclosure.

[0014] The basic idea of ​​this disclosure is to implement a dimmer using a component with an adjustable resistance value. The varying resistance value is converted into a frequency signal with varying frequencies by an impedance-to-frequency converter network. This frequency signal is transmitted in isolation to a controller via a single optocoupler. The controller then identifies the frequency from the signal and, based on this, controls the output current of the connected LED driver. This creates a cost-effective, isolated dimming solution.

[0015] Fig.Figure 1 shows a schematic diagram of the LED driver device (100). It can comprise an LED driver (20) and a dimming device (10) connected to the switching transistor of the LED driver (20). The dimming device (10) dims the LED by changing the duty cycle of the conduction time of the switching transistor in the LED driver (20). Since the present disclosure does not relate to an improvement of the LED driver (20) itself, and its operation is known to those skilled in the art, the LED driver (20) is not described in further detail here in order to avoid unnecessarily obscuring the inventive idea.

[0016] In detail, as in Fig. As shown in 1, the dimming device (10) may include: • A dimmer (101) containing a resistance component with an adjustable value (not shown). • An impedance-frequency converter network (102) connected to the resistance component to convert its resistance value into a frequency signal. • A controller (103) connected to the network (102) to receive the isolated DIM frequency signal as a dimming signal. The controller identifies the frequency of the DIM signal and controls the output current of the LED driver (20) accordingly.

[0017] As in Fig. As shown in Figure 2, the resistance component of the dimmer (101) can consist of at least two resistance units connected in parallel. Each unit comprises a switch (e.g., S1) connected in series and a resistor (e.g., RP1). In the example shown, there are N units (S1 / RP1 to SN / RPN). The switches S1-SN can be DIP switches, allowing a user to change the state of the circuit to adjust the brightness.

[0018] The impedance-frequency converter network (102) comprises: • A first RC charge / discharge network (1020) with a first resistor (R3) and a first capacitor (C3). • A second RC charge / discharge network (1021) with a second resistor (R2) and a second capacitor (C2).

[0019] The circuit is designed to create a self-sustaining oscillation. This requires a phase shift of 180 degrees, which is achieved by combining the two RC networks (since each RC network contributes 90 degrees). The signal is then transmitted in isolation to the controller (103) via the optocoupler (1022).

[0020] As in Fig. As shown in Figure 3, this embodiment differs from the first in that the resistance component of the dimmer (101) This is a sliding resistor (RV). Adjusting the slider changes the resistance value fed into the circuit, which in turn changes the frequency of the output signal of the impedance-frequency converter network.

[0021] The following describes the operating principle with reference to Fig. 4 and Fig. 5 described.

[0022] Fig. Figure 4 shows an example circuit of the converter network. The diode (DA) has a reference terminal (point C) at 2.495V. • When the voltage at point C is below 2.495V, the diode (DA) is reverse-biased. Points A and B are charged. The NPN transistor (Q1) and the optocoupler (1022) are active, therefore the output D is at a low level. • When the voltage at point C rises above 2.495V, the diode (DA) becomes conductive. Points A and B discharge. The transistor (Q1) and the optocoupler (1022) become inactive, therefore the output D goes to a high level.

[0023] This cycle generates an oscillating frequency at point D. Changing the resistance value of the dimmer (which is connected in parallel with R3) changes the time constant of the RC network and thus the frequency. For example, changing the resistance from 20 kΩ to 10 kΩ can change the frequency at point D from 880 Hz to 1230 Hz.

[0024] The controller (103) uses its edge-trigger circuit (1030) to detect the edges of the signal at point D and thus measure its frequency, as shown in Fig. 5 shown.

[0025] Example with 4 dimming levels (Table 1): Assume the dimmer has two resistor units (S1 / RP1 and S2 / RP2), as shown in Fig.2. This allows for four states: Condition Switch S1 Switch S2 Time constant of the first RC element 1 Open Open R3 * C3 2 Open Closed (R3 / / RP2) * C3 3 Closed Open (R3 / / RP1) * C3 4 Closed Closed (R3 / / RP1 / / RP2) * C3 Note: / / denotes the parallel connection of resistors.

[0026] Each of these four states generates a unique frequency at point D. The controller detects which of the four frequencies is present and sets the output current of the LED driver to one of four predefined values.

[0027] The described embodiments are merely examples. It is understood that technical details not described in detail in one embodiment can be derived from other embodiments. It is obvious to a person skilled in the art that various modifications and improvements can be made within the framework of the basic principles of this disclosure, which also fall within the scope of protection of this disclosure. LEGEND OF REFERENCE MARKS 100 LED driver device 10 Dimming device 20 LED drivers 101 dimmers 102 Impedance-to-Frequency Converter Network 103 Control 1020 First resistor-capacitor charge / discharge network 1021 Second Resistor-Capacitor Charge / Discharge Network 1022 Optocouplers 1030 Edge trigger circuit

Claims

[1] A dimming device, characterized by , that the dimming device includes: a dimmer (101) wherein the dimmer (101) comprises a resistor component with an adjustable resistance value; an impedance-frequency converter network (102) connected to the resistance component to convert the resistance value of the dimmer (101) into a frequency signal, where different resistance values ​​correspond to frequency signals with different frequencies; a controller (103) connected to the impedance-frequency converter network (102) to receive the frequency signal from the impedance-frequency converter network (102), to identify the frequency from the frequency signal and to control the output current of an LED driver (20) connected to the controller (103) based on the identified frequency, the impedance-frequency converter network (102) comprises: an optocoupler (1022) wherein the impedance frequency converter network (102) is connected to the controller (103) via the optocoupler (1022) in order to transmit the frequency signal of the impedance frequency converter network (102) in isolation to the controller (103). [2] Dimming device according to claim 1, characterized by , that the resistance component comprises at least two resistance units connected in parallel, each resistance unit comprising a switch connected in series and a resistor. [3] Dimming device according to claim 2, characterized by that the switches are DIP switches. [4] Dimming device according to claim 1, characterized by that the resistance component is a sliding resistance (RS). [5] Dimming device according to claim 1, characterized by , that the impedance-frequency converter network (102) further comprises: a first resistor-capacitor charge / discharge network (1020) comprising a first resistor (R3) and a first capacitor (C3) connected in series, wherein a first terminal of the first resistor (R3) is connected to a first terminal of the resistive component, and a second terminal of the first resistor (R3) is connected to a second terminal of the resistive component and a first terminal of the first capacitor (C3); a second resistor-capacitor charge / discharge network (1021) comprising a second resistor (R2) and a second capacitor (C2) connected in series, wherein a second terminal of the second resistor (R2) is connected to the first terminal of the first resistor (R3) and a first terminal of the second capacitor (C2), and a second terminal of the first capacitor (C3) is connected to a second terminal of the second capacitor (C2), wherein the resistance value of the resistance component is converted into the frequency signal by the first resistor-capacitor charge / discharge network (1020) and the second resistor-capacitor charge / discharge network (1021). [6] Dimming device according to claim 1, characterized by , that the controller (103) comprises an edge trigger circuit (1030), wherein the edge trigger circuit (1030) is connected to the optocoupler (1022) to receive the frequency signal from the optocoupler (1022) and to identify the frequency from the frequency signal. [7] Dimming device according to claim 5, characterized by , that the impedance-frequency converter network (102) further comprises: a diode (DA) connected in parallel to the second resistor-capacitor charge / discharge network (1021), wherein the cathode of the diode (DA) is connected to the first terminal of the second resistor (R2) and the anode of the diode (DA) is connected to the second terminal of the second capacitor (C2). [8] An LED driver device, characterized by , that the LED driver device comprises an LED driver and a dimming device according to one of claims 1-7, wherein the dimming device is connected to the LED driver.

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