A deep dimming circuit, a lighting device and a DALI lighting system

Abstract

This application provides a deep dimming circuit, a lighting device, and a DALI lighting system, comprising: a constant current source, the constant current source including a dimming chip and a first capacitor; the dimming chip, configured to respond to a PWM control signal, generate a charging control signal in a first timing period to charge the first capacitor with a first current, and generate a PWM dimming signal in a second timing period, the PWM dimming signal corresponding to a second current; a pre-charge automatic shutdown module, configured to generate and output a charging shutdown signal when the voltage of the first capacitor reaches a preset amplitude; the dimming chip is also configured to receive the charging shutdown signal and, in response to the charging shutdown signal, stop charging the first capacitor; an LED module switch module, configured to respond to a synchronous start signal to transmit the PWM dimming signal to the LED module; the LED module starts after the LED module switch module is turned on and dims based on the PWM dimming signal. This circuit achieves the effect of fast single-lamp start-up and synchronous start-up and dimming of multiple lamps.

Description

Technical Field

[0001] This application relates to the field of lighting circuit technology, and in particular to a deep dimming circuit, a lighting device, and a DALI lighting system. Background Technology

[0002] In intelligent lighting scenarios, the DALI protocol is an international standard widely used in indoor lighting control. The system broadcasts commands from the master controller to the slave control units on the bus to achieve rapid switching of lighting scenes. To ensure visual harmony and uniformity, the standard requires that connected luminaires must respond within a specified time window after receiving dimming or turn-on commands, ensuring that all luminaires in the same control group can achieve near-synchronous startup.

[0003] In practical applications, power supplies with high-depth dimming capabilities typically require energy storage capacitors in their circuits to stabilize the output voltage and suppress ripple.

[0004] When starting with deep dimming, the power supply output current is relatively low, resulting in a longer capacitor charging time, which can easily exceed the time window permitted by the protocol. Furthermore, the startup time of different LED luminaires often varies due to differences in their design. Therefore, high-depth dimming power supplies have shortcomings in both rapid startup of individual lamps and synchronous startup of groups. Summary of the Invention

[0005] Based on the technical problems raised in the background art, this application provides a deep dimming circuit, a lighting device, and a DALI lighting system.

[0006] This application provides a deep dimming circuit, comprising: a constant current source, a pre-charge automatic shutdown module, an LED module switch module, and an LED module; the constant current source includes a dimming chip and a first capacitor, the dimming chip being connected to an external MCU control module, and the first capacitor being connected to the dimming chip; the pre-charge automatic shutdown module has its input terminal connected to the first capacitor, and its output terminal connected to both the dimming chip and the LED module; the LED module switch module is connected to the MCU control module and is connected between the dimming chip and the LED module; the dimming chip is configured to receive a PWM control signal from the MCU control module; in response to the PWM control signal, it generates a charging control signal in a first timing period to charge the first capacitor with a first current, and generates a PWM dimming signal in a second timing period. The PWM dimming signal corresponds to the second current; the pre-charge automatic shutdown module is configured to generate and output a charging shutdown signal when the voltage of the first capacitor reaches a preset amplitude; the dimming chip is further configured to receive the charging shutdown signal and, in response to the charging shutdown signal, stop charging the first capacitor; the LED module switch module is configured to receive and respond to a synchronous start signal from the MCU control module, and transmit the PWM dimming signal to the LED module; the LED module starts after the LED module switch module is turned on, and dims based on the PWM dimming signal.

[0007] In one possible implementation, the dimming chip includes: a first pin connected to the first capacitor via a first resistor, configured to output a high level corresponding to the charging control signal to the first capacitor; a second pin connected to the input terminal of the LED module, configured to output a high level corresponding to the PWM dimming signal to the LED module; a third pin connected to the MCU control module and the pre-charge automatic shutdown module respectively, configured to receive the PWM control signal and the charging shutdown signal; and a fifth pin connected to the gate of the first MOSFET via a second resistor, the drain of the first MOSFET being connected to the output terminal of the LED module via a first inductor, and the source of the first MOSFET being grounded, configured to output a pulse width modulation signal corresponding to the PWM dimming signal through the first MOSFET.

[0008] In one possible implementation, the first capacitor is an electrolytic capacitor, and the amplitude of the first current is not lower than a preset threshold, the preset threshold being determined based on the second timing time and the capacitance value of the electrolytic capacitor.

[0009] In one possible implementation, the constant current source further includes a ninth resistor connected in parallel across the first capacitor and configured to provide a discharge circuit for the first resistor.

[0010] In one possible implementation, the pre-charge automatic shutdown module includes: a third transistor, the emitter and base of which are respectively connected to the two ends of a sixth resistor; the sixth resistor is connected between the second pin and the input terminal of the LED module and is configured to provide a bias voltage to the third transistor; and a fourth transistor, the base of which is connected to the collector of the third transistor, the emitter of which is grounded, and the collector of which is used to output a low level corresponding to the charging shutdown signal.

[0011] In one possible implementation, the pre-charge automatic shutdown module further includes: a seventh resistor connected between the sixth resistor and the base of the third transistor; and an eighth resistor connected between the collector of the third transistor and the base of the fourth transistor.

[0012] In one possible implementation, the LED module switching module includes: a second transistor, the base of which is connected to the MCU control module through a third resistor, and the emitter of which is grounded; a fourth resistor and a fifth resistor connected in series between the collector of the second transistor and the sixth resistor; and a fifth MOSFET, the gate and drain of which are respectively connected to the two ends of the fifth resistor, and the gate and source of which are located at the two ends of the sixth resistor.

[0013] In one possible implementation, the LED module switching module further includes a second diode connected in parallel across the fifth MOS transistor.

[0014] A second aspect of this application provides a lighting device having a depth dimming circuit as described in any of the claims of the first aspect of this application.

[0015] The third aspect of this application provides a DALI lighting system having at least two lighting devices, each of which has a depth dimming circuit as described in any of the claims of the first aspect of this application.

[0016] This application provides a deep dimming circuit, lighting device, and DALI lighting system. When the voltage across the first capacitor is lower than the turn-on voltage of the LED module, the LED module does not emit light. When the voltage across the first capacitor approaches the turn-on voltage of the LED module, the pre-charge automatic shutdown module detects current flow and sends a feedback signal to the dimming chip. The dimming chip responds to the feedback signal and stops charging the first capacitor. When the circuit receives a synchronous start signal from the external MCU control module, the LED module can start immediately, achieving rapid lighting. This solves the problem of slow single-lamp start-up due to small charging current under deep dimming, avoids the problem of dim standby brightness, and ensures rapid response and dimming of the LED module under synchronous start signal. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This paper shows a functional module diagram of a depth dimming circuit according to an embodiment of the present application; Figure 2 A schematic diagram of the circuit composition of a depth dimming circuit according to an embodiment of this application is shown.

[0019] The reference numerals in the attached diagram are as follows: 100, MCU control module; 200, constant current source; 300, pre-charge automatic shutdown module; 400, LED module switch module; 500, LED module; N1, dimming chip; C1, first capacitor; C2, second capacitor; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; R7, seventh resistor; R8, eighth resistor; R9, ninth resistor; Q1, first MOSFET; Q2, second transistor; Q3, third transistor; Q4, fourth transistor; Q5, fifth MOSFET; L1, first inductor; D2, second diode. Detailed Implementation

[0020] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third" are configured for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0023] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0024] Figure 1 This paper shows a functional module diagram of a depth dimming circuit according to an embodiment of the present application; Figure 2 A schematic diagram of the circuit composition of a depth dimming circuit according to an embodiment of this application is shown.

[0025] See Figure 1 and Figure 2 The first aspect of this application provides a deep dimming circuit, including: a constant current source 200, a pre-charge automatic shutdown module 300, an LED module switch module 400, and an LED module 500.

[0026] The constant current source 200 includes a dimming chip N1 and a first capacitor C1. The dimming chip N1 is connected to an external MCU control module 100, and the first capacitor C1 is connected to the dimming chip N1. The pre-charge automatic shutdown module 300 has its input connected to the first capacitor C1, and its output connected to both the dimming chip N1 and the LED module 500. The LED module switch module 400 is connected to the MCU control module 100 and is positioned between the dimming chip N1 and the LED module 500.

[0027] The deep dimming circuit provided in this application embodiment uses a dimming chip N1 to charge a first capacitor C1. When the voltage across the first capacitor C1 is lower than the turn-on voltage of the LED module 500, the LED module 500 does not emit light, and the first capacitor C1 continues to charge. When the voltage across the first capacitor C1 approaches the turn-on voltage of the LED module 500, the pre-charge automatic shutdown module 300 detects current flow and sends a feedback signal to the dimming chip N1. The dimming chip N1 responds to the feedback signal and stops charging the first capacitor C1, thereby preventing the LED module 500 from being "slightly lit" before it is officially turned on. At this time, since the first capacitor C1 has been pre-charged to a state close to the turn-on voltage, when the circuit receives a synchronous start signal from the external MCU control module 100, the LED module 500 can start immediately, achieving rapid lighting. This solves the problem of slow single-lamp start-up caused by small charging current under deep dimming, avoids the problem of slightly lit standby, and ensures the rapid response and dimming of the LED module 500 under the synchronous start signal. The circuit has a simple structure, relies mainly on hardware control, has a fast response speed, high stability, and low cost.

[0028] Specifically, the constant current source 200 includes a dimming chip N1 and a first capacitor C1. The dimming chip N1 is connected to the external MCU control module 100, and the first capacitor C1 is connected to the dimming chip N1.

[0029] The dimming chip N1 is configured to receive a PWM control signal from the MCU control module 100; in response to the PWM control signal, it generates a charging control signal in a first timing period to charge the first capacitor C1 with a first current, and generates a PWM dimming signal in a second timing period, the PWM dimming signal corresponding to the second current.

[0030] The PWM control signal is a pulse signal sent by the external MCU control module 100 to the dimming chip N1. This signal can have different functions in different working stages. In the power-on stage, the MCU control module 100 can send a PWM signal with a predetermined pulse width as a start-up trigger signal to enable the dimming chip N1 to precharge the first capacitor C1. In the dimming working stage, the MCU control module 100 transmits brightness control information to the dimming chip N1 by adjusting the duty cycle of the PWM signal.

[0031] The first timing sequence is earlier than the second timing sequence. Furthermore, when the circuit provided in this embodiment is applied to a DALI lighting system, the interval between the first and second timing sequences does not exceed the startup time of the LED module 500 specified by the DALI lighting system.

[0032] To achieve fast charging, the first current is typically the maximum current the circuit can provide. The capacitor needs to be fully charged before the second timing time, meaning the lower limit of the first current is the current value that can fully charge the capacitor before the second timing time arrives.

[0033] Based on the required brightness of the PWM control signal, the second current corresponding to the PWM dimming signal can be any value within the dimming range of 0 to 100. That is, the second current can be any value between the minimum and maximum current that the circuit can provide.

[0034] The pre-charge automatic shutdown module 300 has its input terminal connected to the first capacitor C1, and its output terminal connected to the dimming chip N1 and the LED module 500, respectively. The pre-charge automatic shutdown module 300 is configured to generate and output a charging shutdown signal when the voltage of the first capacitor C1 reaches a preset amplitude.

[0035] The pre-charge automatic shutdown module 300 is connected between the first chip and the LED module 500, enabling it to detect the current flowing to the LED module 500 and promptly output a charging shutdown signal to the dimming chip N1. The dimming chip N1 is also configured to receive the charging shutdown signal and, in response, stop charging the first capacitor C1. This prevents the voltage across the first capacitor C1 from reaching the turn-on voltage of the LED module 500, thus preventing the LED module 500 from dimly lighting up before the LED module switching module 400 is turned on.

[0036] The LED module switch module 400 is connected to the MCU control module 100 and is connected between the dimming chip N1 and the LED module 500. The LED module switch module 400 is configured to receive and respond to the synchronous start signal from the MCU control module 100 and transmit the PWM dimming signal to the LED module 500.

[0037] In practical applications, the MCU control module 100 can simultaneously send the PWM control signal and the synchronization start signal to the dimming chip N1 and the LED module switch module 400, respectively, or it can send the PWM control signal and the synchronization start signal to the dimming chip N1 and the LED module switch module 400 in stages. In this embodiment, when the MCU control module 100 can simultaneously send the PWM control signal and the synchronization start signal to the dimming chip N1 and the LED module switch module 400, the second timing time is the start time required by the DALI protocol. By rapidly charging the first capacitor C1, the charging of the first capacitor C1 can be completed within the start time required by the DALI protocol. Furthermore, by controlling the second timing time, it can be ensured that all lamps in the DALI lighting system are lit synchronously.

[0038] LED module 500 is activated after LED module switch module 400 is turned on, and dimming is performed based on PWM dimming signal.

[0039] In one possible implementation, the dimming chip N1 includes: The first pin is connected to the first capacitor C1 through the first resistor R1 and is configured to output a high level corresponding to the charging control signal to the first capacitor C1.

[0040] The second pin is connected to the input terminal of the LED module 500 and is configured to output a high level corresponding to the PWM dimming signal to the LED module 500.

[0041] The third pin is connected to the MCU control module 100 and the precharge automatic shutdown module 300 respectively, and is configured to receive PWM control signals and charging shutdown signals.

[0042] The fifth pin is connected to the gate of the first MOSFET Q1 through the second resistor R2. The drain of the first MOSFET Q1 is connected to the output terminal of the LED module 500 through the first inductor L1. The source of the first MOSFET Q1 is grounded and is configured to output the pulse width modulation signal corresponding to the PWM dimming signal through the first MOSFET Q1.

[0043] The dimming chip N1 also includes: The fourth pin is connected to the source of the first MOSFET Q1 and grounded; The sixth pin is connected to the second capacitor C2 and grounded.

[0044] The dimming chip N1, the first resistor R1, the first diode, the first inductor L1, and the first MOSFET Q1 form a BUCK circuit, which realizes the design of a constant current circuit.

[0045] In one possible implementation, the first capacitor C1 is an electrolytic capacitor, and the amplitude of the first current is not lower than a preset threshold. The preset threshold is determined based on a second timing time and the capacitance value of the electrolytic capacitor. Specifically, according to C=Q / U and Q=I*T, we know that I=CU / T, where C is used to characterize the capacitance value of the first capacitor C1, U is used to characterize the change in voltage across the first capacitor C1, and T is used to characterize the charging time of the first capacitor C1, which is set to not exceed the time interval between the first timing time and the second timing time.

[0046] In one possible implementation, the constant current source 200 further includes a ninth resistor R9, connected in parallel across the first capacitor C1, configured to provide a discharge circuit for the first resistor R1. The ninth resistor R9 provides a discharge circuit for the first resistor R1 when the dimming chip N1 stops charging, preventing the LED module 500 from exhibiting dim lighting.

[0047] In one possible implementation, the pre-charge automatic shutdown module 300 includes: a third transistor Q3, whose emitter and base are respectively connected to the two ends of a sixth resistor R6; the sixth resistor R6 is connected between the second pin and the input terminal of the LED module 500 and is configured to provide a bias voltage to the third transistor Q3; and a fourth transistor Q4, whose base is connected to the collector of the third transistor Q3, whose emitter is grounded, and whose collector is used to output a low level corresponding to the charging shutdown signal.

[0048] When the voltage across the first capacitor C1 approaches the turn-on voltage of the LED module 500, current begins to flow through the sixth resistor R6. The voltage difference across the sixth resistor R6 is close to the turn-on voltage of the third transistor Q3. At this time, a weak current flows through the third transistor Q3, causing it to turn on. Furthermore, current flows through the fourth transistor Q4, causing it to conduct and output a low level to the dimming chip N1. The third transistor Q3 is a PNP transistor, and the fourth transistor Q4 is an NPN transistor.

[0049] In one possible implementation, the pre-charge automatic shutdown module 300 further includes: a seventh resistor R7 connected between a sixth resistor R6 and the base of a third transistor Q3; and an eighth resistor R8 connected between the collector of the third transistor Q3 and the base of a fourth transistor Q4. The seventh resistor R7 and the eighth resistor R8 serve as protection resistors corresponding to the third transistor Q3 and the fourth transistor Q4, respectively, to protect the third transistor Q3 and the fourth transistor Q4.

[0050] Correspondingly, the third pin of the dimming chip N1 receives a low level from the fourth transistor Q4, so that the EN pin is pulled low, stopping the charging of the first capacitor C1.

[0051] In one possible implementation, the LED module switch module 400 includes: a second transistor Q2, whose base is connected to the MCU control module 100 through a third resistor R3, and whose emitter is grounded; a fourth resistor R4 and a fifth resistor R5, which are connected in series between the collector of the second transistor Q2 and a sixth resistor R6; and a fifth MOSFET Q5, whose gate and drain are respectively connected to the two ends of the fifth resistor R5, and whose gate and source are located at the two ends of the sixth resistor R6.

[0052] When the light needs to be turned on, the external MCU control module 100 sends a synchronous start signal to the LED switch module. The synchronous start signal turns on the second transistor Q2. In the voltage divider circuit composed of the fourth resistor R4 and the fifth resistor R5, the voltage across the fifth resistor R5 is greater than the turn-on voltage of the fifth MOSFET Q5, causing the fifth MOSFET Q5 to conduct, thus achieving rapid start-up.

[0053] In one embodiment, the LED module switch module 400 further includes a second diode D2 connected in parallel across the fifth MOSFET Q5. The second diode D2 provides protection for the fifth MOSFET Q5. Using the above circuit, only simple software configuration on the dimming chip N1 is required to achieve synchronous startup of the constant current deep dimming power supply. This not only ensures fast startup of a single lamp but also guarantees synchronous startup of multiple lamps. The components are simple, primarily using hardware control, resulting in fast response, high stability, and low cost.

[0054] A second aspect of this application provides a lighting device having a depth dimming circuit as provided in any of the first aspects of this application.

[0055] A third aspect of this application provides a DALI lighting system having at least two lighting devices, each of which has a depth dimming circuit as provided in any of the first aspects of this application.

[0056] While exemplary embodiments and their advantages have been described in detail, those skilled in the art can make various changes, substitutions, and modifications to these embodiments without departing from the spirit of this application and the scope of protection defined by the appended claims. Such modifications and variations all fall within the scope defined by the appended claims. For other examples, those skilled in the art should readily understand that the order of process steps can be changed while remaining within the scope of protection of this application.

[0057] Furthermore, the scope of this application is not limited to the processes, mechanisms, manufacturing methods, material compositions, means, methods, and steps of the specific embodiments described in the specification. From the disclosure of this application, those skilled in the art will readily understand that any existing or future processes, mechanisms, manufacturing methods, material compositions, means, methods, or steps that perform substantially the same function or achieve substantially the same results as the corresponding embodiments described in this application can be applied in accordance with this application. Therefore, the appended claims are intended to include these processes, mechanisms, manufacturing methods, material compositions, means, methods, or steps within their scope of protection.

Claims

1. A depth dimming circuit with synchronous start-up function, characterized in that, include: A constant current source (200), a pre-charge automatic shutdown module (300), an LED module switch module (400), and an LED module (500). The constant current source (200) includes a dimming chip (N1) and a first capacitor (C1). The dimming chip (N1) is connected to an external MCU control module (100), and the first capacitor (C1) is connected to the dimming chip (N1). The pre-charge automatic shutdown module (300) has its input terminal connected to the first capacitor (C1) and its output terminal connected to the dimming chip (N1) and the LED module (500) respectively. The LED module switch module (400) is connected to the MCU control module (100) and is connected between the dimming chip (N1) and the LED module (500); The dimming chip (N1) is configured to receive a PWM control signal from the MCU control module (100); in response to the PWM control signal, it generates a charging control signal in a first timing period to charge the first capacitor (C1) with a first current, and generates a PWM dimming signal in a second timing period, the PWM dimming signal corresponding to a second current; The pre-charge automatic shutdown module (300) is configured to generate and output a charging shutdown signal when the voltage of the first capacitor (C1) reaches a preset amplitude. The dimming chip (N1) is also configured to receive the charging off signal and, in response to the charging off signal, stop charging the first capacitor (C1). The LED module switch module (400) is configured to receive and respond to a synchronous start signal from the MCU control module (100) and transmit the PWM dimming signal to the LED module (500). The LED module (500) is activated after the LED module switch module (400) is turned on, and dims based on the PWM dimming signal.

2. The depth dimming circuit according to claim 1, characterized in that, The dimming chip (N1) includes: The first pin is connected to the first capacitor (C1) through the first resistor (R1) and is configured to output a high level corresponding to the charging control signal to the first capacitor (C1); The second pin is connected to the input terminal of the LED module (500) and is configured to output a high level corresponding to the PWM dimming signal to the LED module (500); The third pin is connected to the MCU control module (100) and the precharge automatic shutdown module (300) respectively, and is configured to receive the PWM control signal and the charging shutdown signal; The fifth pin is connected to the gate of the first MOSFET (Q1) through the second resistor (R2). The drain of the first MOSFET (Q1) is connected to the output terminal of the LED module (500) through the first inductor (L1). The source of the first MOSFET (Q1) is grounded and is configured to output a pulse width modulation signal corresponding to the PWM dimming signal through the first MOSFET (Q1).

3. The depth dimming circuit according to claim 1, characterized in that, The first capacitor (C1) is an electrolytic capacitor, and the amplitude of the first current is not lower than a preset threshold. The preset threshold is determined based on the second timing time and the capacitance value of the electrolytic capacitor.

4. The depth dimming circuit according to claim 1, characterized in that, The constant current source (200) also includes: The ninth resistor (R9), connected in parallel across the first capacitor (C1), is configured to provide a discharge path for the first resistor (R1).

5. The depth dimming circuit according to claim 2, characterized in that, The pre-charge automatic shutdown module (300) includes: The emitter and base of the third transistor (Q3) are connected to the two ends of the sixth resistor (R6), respectively. The sixth resistor (R6), connected between the second pin and the input of the LED module (500), is configured to provide a bias voltage to the third transistor (Q3); The fourth transistor (Q4) has its base connected to the collector of the third transistor (Q3), its emitter grounded, and its collector used to output a low level corresponding to the charging off signal.

6. The depth dimming circuit according to claim 5, characterized in that, The pre-charge automatic shutdown module (300) also includes: The seventh resistor (R7) is connected between the sixth resistor (R6) and the base of the third transistor (Q3); The eighth resistor (R8) is connected between the collector of the third transistor (Q3) and the base of the fourth transistor (Q4).

7. The depth dimming circuit according to claim 5, characterized in that, The LED module switch module (400) includes: The base of the second transistor (Q2) is connected to the MCU control module (100) through the third resistor (R3), and its emitter is grounded; The fourth resistor (R4) and the fifth resistor (R5) are connected in series between the collector of the second transistor (Q2) and the sixth resistor (R6); The fifth MOS transistor (Q5) has its gate and drain connected to the two ends of the fifth resistor (R5), and its gate and source are located at the two ends of the sixth resistor (R6).

8. The depth dimming circuit according to claim 7, characterized in that, The LED module switch module (400) also includes: The second diode (D2) is connected in parallel across the fifth MOSFET (Q5).

9. A lighting device, characterized in that, It has a depth dimming circuit as described in any one of claims 1 to 8.

10. A DALI lighting system, characterized in that, It has at least two lighting devices, each of which has a depth dimming circuit as described in any one of claims 1 to 8.

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