Dimmer and illumination system

Abstract

To provide a dimmer and an illumination system, capable of suppressing troublesome for cancelling a protection state of an overcurrent while rapidly protecting the overcurrent with a simpler construction.SOLUTION: A dimmer comprises: a signal generation device that receives an input of an operation signal in accordance with an operation instruction in regard to a dimmer level of a light irradiated from a lighting tool, and generates a control signal for generating a dimmer signal of the dimmer level in accordance with the operation signal; a signal output circuit that generates the dimmer signal of the dimmer level in accordance with the operation signal on the basis of the control signal and detects a current of the dimmer signal; an overcurrent protection circuit that performs an overcurrent protection operation that stops an output of the dimmer signal to the signal output circuit in accordance with a detection of an overcurrent of the dimmer signal. The overcurrent protection circuit stops the overcurrent protection operation in accordance with a switch of the control signal when performing the overcurrent protection operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DIMENSIONS FIELD OF THE DISCLOSURE Embodiments of the present invention relate to dimmers and lighting systems. [Background technology]

[0002] There is a lighting system that includes a lighting fixture and a dimmer. The lighting fixture has a light source and illuminates a space by emitting light from the light source. The dimmer is connected to the lighting fixture via a signal line and transmits a dimming signal to the lighting fixture to change the brightness of the light emitted from the lighting fixture. The lighting fixture changes the brightness of the light emitted from the light source in response to the dimming signal received from the dimmer. In this way, the lighting system can arbitrarily change the brightness of the light emitted from the lighting fixture in response to the dimming signal from the dimmer, and illuminate a space at any brightness.

[0003] The dimming signal is a pulse signal that alternates between a first state with a low voltage and a second state with a high voltage. The dimmer changes the brightness of the light emitted from the lighting fixture by changing the interval between the first and second states of the dimming signal.

[0004] In the above-mentioned dimmer, if an unintended load, such as an incompatible lighting fixture, is connected via the signal line, or if the signal line is shorted due to a wiring fault, an overcurrent may flow in the signal line when the dimming signal is switched from the first state to the second state. An overcurrent flowing in the signal line may cause the dimmer or lighting fixture to malfunction.

[0005] For this reason, a dimmer is provided with an overcurrent protection function that detects an overcurrent flowing in a signal line and stops switching of the dimming signal to the second state upon detection of an overcurrent.

[0006] On the other hand, once the overcurrent protection function is activated and an overcurrent protection state is established, the overcurrent protection state cannot be released even if the overcurrent state is resolved unless a reset operation such as turning the power of the dimmer itself on and off is performed. In this way, when an overcurrent protection function is provided, it takes time to release the overcurrent protection state. Also, when the overcurrent protection function is activated, the brightness of the light emitted from the lighting fixture cannot be changed until a reset operation is performed.

[0007] For example, it has been proposed to suppress operation of the overcurrent protection function due to a transient overcurrent caused by the floating capacitance of the signal line, by prohibiting operation of the overcurrent protection function for a predetermined time from the timing of switching the dimming signal from the first state to the second state. This makes it possible to suppress, for example, operation of the overcurrent protection function due to a short-term transient overcurrent that does not affect the operation of the dimmer. Unintended operation of the overcurrent protection function due to a transient overcurrent can be suppressed, and the effort required to release the overcurrent protection state can be reduced.

[0008] However, even if the operation of the overcurrent protection function due to a transient overcurrent is suppressed as described above, when an overcurrent actually occurs, it is still necessary to release the overcurrent protection state. Furthermore, when the operation of the overcurrent protection function due to a transient overcurrent is suppressed, there is a concern that a delay will occur in overcurrent protection when an overcurrent actually occurs, and a timer circuit or the like will be required to measure a predetermined time, which may complicate the configuration of the dimmer.

[0009] For this reason, it is desirable for a dimmer to be able to provide overcurrent protection more quickly with a simpler configuration, and to reduce the effort required to release the overcurrent protection state. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2011-210620 A Summary of the Invention [Problem to be solved by the invention]

[0011] The object is to provide a dimmer and a lighting system that can provide overcurrent protection more quickly with a simpler configuration and can reduce the effort required to release the overcurrent protection state. [Means for solving the problem]

[0012] According to an embodiment of the present invention, there is provided a dimmer that is connected to a lighting fixture via a pair of signal lines and transmits a dimming signal to the lighting fixture for changing the brightness of light irradiated from the lighting fixture, the dimmer including: a signal generator that receives an input of an operation signal corresponding to an operation instruction regarding a dimming level of light irradiated from the lighting fixture and generates a control signal for generating the dimming signal with a dimming level corresponding to the input operation signal; a signal output circuit that receives an input of a current detection signal representing a magnitude of the current of the dimming signal detected from the signal output circuit, detects an overcurrent of the dimming signal based on the current detection signal, and outputs a protection signal to the signal output circuit in response to the detection of an overcurrent of the dimming signal. and an overcurrent protection circuit that performs an overcurrent protection operation to cause the signal output circuit to stop output of the dimming signal by inputting the dimming signal to a signal output circuit, wherein the dimming signal is a pulse signal that alternates between a first state having a low voltage and a second state having a high voltage, and the control signal is a pulse signal that alternates between a third state for setting the dimming signal to the first state and a fourth state for setting the dimming signal to the second state, and the overcurrent protection circuit receives the current detection signal from the signal output circuit and the control signal from the signal generator, and stops the input of the protection signal to the signal output circuit in response to a switching of the control signal from the third state to the fourth state or from the fourth state to the third state when performing the overcurrent protection operation. Effect of the Invention

[0013] According to an embodiment of the present invention, a dimmer and lighting system can be provided that has a simpler configuration, can provide overcurrent protection more quickly, and can reduce the effort required to release the overcurrent protection state. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram illustrating a lighting system according to an embodiment. [Diagram 2] FIG. 1 is a block diagram illustrating a dimmer according to an embodiment. [Diagram 3] 1 is a block diagram illustrating an example of an overcurrent protection circuit according to an embodiment; [Figure 4] 4 is a timing chart illustrating an example of an operation of the dimmer according to the embodiment. [Diagram 5] 10 is a timing chart illustrating an example of another operation of the dimmer according to the embodiment. [Figure 6] FIG. 11 is a block diagram illustrating a modified example of the dimmer according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Each embodiment will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as in reality. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals and detailed descriptions thereof will be omitted as appropriate.

[0016] FIG. 1 is a block diagram illustrating a lighting system according to an embodiment. 1, the lighting system 2 includes a lighting fixture 4 and a dimmer 10. The lighting fixture 4 has a light source 4a. The lighting fixture 4 illuminates a space by emitting light from the light source 4a. The lighting fixture 4 also has a dimming function that changes the brightness of the light emitted from the light source 4a.

[0017] The light source 4a is, for example, a light emitting diode (LED). The light source 4a may be, for example, an organic light emitting diode (OLED), an inorganic electroluminescence light emitting element, an organic electroluminescence light emitting element, or other electroluminescence type light emitting element. The light source 4a may be, for example, a light bulb. The light source 4a may be any light source that can irradiate light in response to the supply of power and change the brightness of the irradiated light. The light source 4a is not limited to one element, and may be, for example, a plurality of elements connected in series, in parallel, or in a combination of series and parallel.

[0018] The dimmer 10 is connected to the lighting fixture 4 via a pair of signal lines 6a, 6b. The dimmer 10 transmits a dimming signal to the lighting fixture 4 to change the brightness of the light emitted from the lighting fixture 4. The lighting fixture 4 changes the brightness of the light emitted from the light source 4a in response to the dimming signal received from the dimmer 10. In this way, the lighting system 2 can arbitrarily change the brightness of the light emitted from the lighting fixture 4 in response to the dimming signal from the dimmer 10, and illuminate a space at any brightness.

[0019] The lighting fixture 4 and the dimmer 10 are connected to a power source PS. The power supplied by the power source PS is, for example, AC power. The power source PS is, for example, a commercial power source. The power source PS may be, for example, a private power generator. The power supplied by the power source PS may be, for example, DC power.

[0020] The lighting device 4 converts the power supplied from the power source PS into power suitable for the light source 4a and supplies the converted power to the light source 4a, thereby causing the light source 4a to emit light. The lighting device 4 also changes the brightness of the light emitted from the light source 4a by controlling the power supplied to the light source 4a.

[0021] The dimmer 10 transmits a dimming signal to the lighting fixture 4 based on the power supplied from the power source PS. The power source PS to which the dimmer 10 is connected may be the same as the power source PS to which the lighting fixture 4 is connected, or it may be different. For example, the dimmer 10 may be connected to a power source PS that supplies AC power, and the lighting fixture 4 may be connected to another power source PS that supplies DC power.

[0022] FIG. 2 is a block diagram illustrating a dimmer according to the embodiment. As shown in FIG. 2, the dimmer 10 includes a conversion circuit 12, a control power supply circuit 14, a signal generator 16, an operation unit 18, a signal output circuit 20, and an overcurrent protection circuit 22.

[0023] The conversion circuit 12 is connected to the power source PS. The conversion circuit 12 converts the power supplied from the power source PS into DC power compatible with the signal output circuit 20, and supplies the converted DC power to the signal output circuit 20. The conversion circuit 12 converts, for example, the AC power supplied from the power source PS into DC power compatible with the signal output circuit 20, and supplies the converted DC power to the signal output circuit 20. The conversion circuit 12 is, for example, an AC-DC converter. More specifically, the conversion circuit 12 converts the AC power of 100V (effective value) of the power source PS into DC power of 13V, and supplies the converted DC power to the signal output circuit 20.

[0024] For example, when the power supplied from the power source PS is DC power, the conversion circuit 12 may be omitted. The power supplied to the signal output circuit 20 is not limited to the power of the conversion circuit 12, and may be the power supplied from the power source PS as is. The conversion circuit 12 is provided as necessary and may be omitted.

[0025] In this example, the conversion circuit 12 supplies the converted DC power to the signal output circuit 20, and also to the control power supply circuit 14 and the overcurrent protection circuit 22. However, the power supplied to the control power supply circuit 14 and the overcurrent protection circuit 22 is not limited to the power of the conversion circuit 12, and may be any power.

[0026] The control power supply circuit 14 generates DC power corresponding to the signal generator 16 from the DC power supplied from the conversion circuit 12, and supplies the generated DC power to the signal generator 16. The control power supply circuit 14 generates, for example, 3.3 V DC power from the 13 V DC power supplied from the conversion circuit 12, and supplies the generated DC power to the signal generator 16. The control power supply circuit 14 is, for example, a step-down circuit.

[0027] However, the configuration of the control power supply circuit 14 is not limited to this, and may be any configuration capable of generating DC power corresponding to the signal generator 16. The configuration of the control power supply circuit 14 may be set appropriately depending on, for example, the power supplied from the power supply PS, the configuration of the conversion circuit 12, and the configuration of the signal generator 16. Furthermore, for example, in cases where the DC power output from the conversion circuit 12 can be directly supplied to the signal generator 16, the control power supply circuit 14 may be omitted.

[0028] The signal generator 16 operates in response to the supply of DC power from the control power supply circuit 14. The DC power supplied from the control power supply circuit 14 to the signal generator 16 is, in other words, a power source for operating the signal generator 16.

[0029] Signal generator 16 is connected to operation unit 18. Operation unit 18 receives an input of an operation instruction related to the dimming level of light emitted from lighting fixture 4, and inputs, to signal generator 16, an operation signal representing the dimming level according to the input operation instruction.

[0030] Operation unit 18 is, for example, a sliding or rotating type manually operable operation input member. Operation unit 18 may be any member that allows a user to manually set the dimming level of the light emitted from lighting device 4 and inputs an operation signal representing the set dimming level to signal generator 16.

[0031] Signal generator 16 receives an operation signal corresponding to an operation instruction related to the dimming level of light emitted from lighting fixture 4. In this example, signal generator 16 receives an operation signal from operation unit 18. Signal generator 16 generates a control signal for generating a dimming signal with a dimming level corresponding to the input operation signal. Signal generator 16 inputs the generated control signal to signal output circuit 20.

[0032] The signal output circuit 20 has a pair of output terminals 20a, 20b. The signal output circuit 20 is connected to a pair of signal lines 6a, 6b via the pair of output terminals 20a, 20b. In other words, the signal output circuit 20 is connected to the lighting fixture 4 via the pair of output terminals 20a, 20b and the pair of signal lines 6a, 6b.

[0033] Based on the control signal input from signal generator 16, signal output circuit 20 generates a dimming signal having a dimming level corresponding to the operation signal, and outputs the generated dimming signal from a pair of output terminals 20a, 20b. In other words, signal output circuit 20 inputs the generated dimming signal to lighting fixture 4 via a pair of output terminals 20a, 20b and a pair of signal lines 6a, 6b. In this way, lighting system 2 can cause lighting fixture 4 to irradiate light with a brightness corresponding to the operation of operation unit 18 by the user.

[0034] The dimming signal is a pulse signal that alternates between a first state with a low voltage and a second state with a high voltage. The signal output circuit 20 (dimmer 10) changes the brightness of the light emitted from the lighting device 4 by changing the interval between the first and second states of the dimming signal. In other words, the signal output circuit 20 causes the lighting device 4 to emit light with a brightness according to the dimming level by changing the interval between the first and second states of the dimming signal according to the dimming level represented by the control signal.

[0035] The control signal is a pulse signal that alternates between a low voltage state and a high voltage state, similar to the dimming signal. The control signal and dimming signal are, for example, PWM (Pulse Width Modulation) signals that alternate between a low voltage state and a high voltage state at a fixed cycle. The signal output circuit 20 changes the duty ratio of the first state and the second state of the dimming signal according to the dimming level represented by the control signal, thereby causing the lighting device 4 to irradiate light with a brightness according to the dimming level.

[0036] For example, the lighting device 4 and the dimmer 10 define a state where one entire cycle of the dimming signal is in the first state as a dimming level of 100%, and a state where one entire cycle of the dimming signal is in the second state as a dimming level of 0%. This allows the lighting device 4 to emit light at a dimming level of 100% (all lights on) when no dimming signal is input, for example, when the dimmer 10 is not connected or when a malfunction occurs in the dimmer 10. In other words, it is possible to prevent the lighting device 4 from being turned off when no dimming signal is input.

[0037] However, the lighting fixtures 4 and dimmer 10 may be configured to set a dimming level of 0% when the entire cycle of the dimming signal is in the first state and a dimming level of 100% when the entire cycle of the dimming signal is in the second state. In this case, for example, turning off the lighting fixtures 4 can make it easier for a user to recognize that there is a problem with the input of the dimming signal. For example, this can prevent the lighting system 2 from being used continuously when the dimmer 10 is broken.

[0038] The control signal and dimming signal may be, for example, a PFM (Pulse Frequency Modulation) signal that alternates between a low voltage state and a high voltage state by changing the period of a low voltage state while keeping the period of a high voltage state constant. However, the control signal and dimming signal are not limited to these, and may be any pulse signal that can appropriately indicate the dimming level by alternating between a low voltage state and a high voltage state.

[0039] The signal generator 16 is, for example, a microcomputer such as an MCU (Micro Controller Unit). The control signal is, for example, a pulse signal (digital signal) output from a digital output terminal of the MCU. The control signal is, for example, a pulse signal that alternates between 0V (low voltage state) and 3.3V (high voltage state). The magnitude of the voltage of the control signal in the high voltage state is, for example, substantially the same as the magnitude of the voltage of the power supplied from the control power supply circuit 14. However, the configuration of the signal generator 16 is not limited to the above, and may be any configuration that can appropriately generate a control signal.

[0040] The signal output circuit 20 has, for example, a switching element (not shown). The switching element has, for example, a pair of main terminals and a control terminal. The switching element is, for example, a semiconductor switching element such as a MOSFET. One main terminal of the switching element is connected to a high-potential output terminal of the conversion circuit 12. The other main terminal of the switching element is connected to one output terminal 20a. The output terminal 20a is, for example, a high-potential output terminal of the signal output circuit 20, and the output terminal 20b is, for example, a low-potential output terminal of the signal output circuit 20.

[0041] The signal output circuit 20 inputs the control signal input from the signal generator 16 to the control terminal of the switching element. The switching element is in the OFF state when the voltage applied to the control terminal is low, and is in the ON state when the voltage applied to the control terminal is high. This generates a dimming signal that is in the first state when the voltage of the control signal is low, and in the second state when the voltage of the control signal is high.

[0042] The voltage magnitude of the dimming signal in the second state is, for example, substantially the same as the voltage magnitude of the DC power supplied from the conversion circuit 12. The dimming signal is, for example, a pulse signal that alternates between 0 V (first state) and 13 V (second state). Thus, the dimming signal is a pulse signal that is normally synchronized with the control signal and has a larger amplitude (voltage magnitude in a high voltage state) than the control signal.

[0043] However, the configuration of the signal output circuit 20 is not limited to the above, and may be any configuration that can appropriately generate a dimming signal according to the control signal. The dimming signal may be a pulse signal whose logic is inverted from that of the control signal under normal conditions, for example, by setting the dimming signal to a first state when the voltage of the control signal is high and setting the signal to a second state when the voltage of the control signal is low.

[0044] In other words, the control signal is a pulse signal that alternates between a third state for setting the dimming signal to the first state and a fourth state for setting the dimming signal to the second state. In this example, the low voltage state is the third state, and the high voltage state is the fourth state. As described above, the control signal may have the high voltage state as the third state and the low voltage state as the fourth state.

[0045] The signal output circuit 20 generates a dimming signal and detects the current of the dimming signal. For example, the signal output circuit 20 detects the magnitude of the current flowing through the higher potential output terminal 20a of the pair of output terminals 20a, 20b as the magnitude of the dimming signal current. The signal output circuit 20 inputs a current detection signal representing the magnitude of the detected dimming signal current to the overcurrent protection circuit 22.

[0046] The overcurrent protection circuit 22 operates based on the DC power supplied from the conversion circuit 12. The overcurrent protection circuit 22 detects an overcurrent of the dimming signal based on the current detection signal input from the signal output circuit 20. The overcurrent protection circuit 22 sets a predetermined threshold value for the magnitude of the current of the dimming signal represented by the current detection signal, and detects an overcurrent of the dimming signal when the magnitude of the current of the dimming signal becomes equal to or greater than the threshold value.

[0047] The current detection signal input from the signal output circuit 20 to the overcurrent protection circuit 22 is, for example, an analog signal corresponding to the magnitude of the current of the detected dimming signal. For example, the signal output circuit 20 may determine whether the magnitude of the current of the detected dimming signal is equal to or greater than a threshold. The current detection signal may be, for example, a digital signal that is low when the current is less than the threshold (when an overcurrent is not detected) and is high when the current is equal to or greater than the threshold (when an overcurrent is detected). The overcurrent protection circuit 22 may detect an overcurrent of the dimming signal in response to, for example, the current detection signal switching from low to high.

[0048] The overcurrent protection circuit 22 performs an overcurrent protection operation to cause the signal output circuit 20 to stop outputting the dimming signal in response to detection of an overcurrent in the dimming signal. The overcurrent protection circuit 22 inputs a protection signal to the signal output circuit 20 in response to detection of an overcurrent in the dimming signal. When a protection signal is input from the overcurrent protection circuit 22, the signal output circuit 20 stops outputting the dimming signal and sets the dimming signal to the first state regardless of the state of the control signal. In this way, the overcurrent protection circuit 22 performs an overcurrent protection operation by inputting a protection signal to the signal output circuit 20.

[0049] The overcurrent protection circuit 22 receives an input of a current detection signal from the signal output circuit 20, and also receives an input of a control signal from the signal generator 16. The signal generator 16 inputs a control signal to the signal output circuit 20, and also to the overcurrent protection circuit 22.

[0050] When the overcurrent protection circuit 22 performs an overcurrent protection operation, the overcurrent protection circuit 22 stops the overcurrent protection operation by stopping the input of the protection signal to the signal output circuit 20 in response to the control signal switching from the third state to the fourth state or from the fourth state to the third state.

[0051] FIG. 3 is a block diagram illustrating an example of an overcurrent protection circuit according to an embodiment. 3, the overcurrent protection circuit 22 includes two NOR circuits 31 and 32 and a NOT gate 33. The NOR circuits 31 and 32 each include a pair of input terminals and an output terminal. The DC power supplied from the conversion circuit 12 is used as a driving power source for the NOR circuits 31 and 32 and the NOT gate 33, for example.

[0052] The current detection signal input from the signal output circuit 20 is input to one input terminal of the NOR circuit 31. In other words, one input terminal of the NOR circuit 31 is connected to the signal output circuit 20 and receives the current detection signal from the signal output circuit 20. The other input terminal of the NOR circuit 31 is connected to the output terminal of the NOR circuit 32. The output terminal of the NOR circuit 31 is connected to one input terminal of the NOR circuit 32.

[0053] The other input terminal of the NOR circuit 32 receives the control signal input from the signal generator 16 via the NOT gate 33. In other words, the other input terminal of the NOR circuit 32 is connected to the signal generator 16 via the NOT gate 33 and receives the control signal input from the signal generator 16.

[0054] The output terminal of the NOR circuit 32 is connected to the other input terminal of the NOR circuit 31, and also serves as the output terminal of the overcurrent protection circuit 22. The overcurrent protection circuit 22 inputs the output signal of the NOR circuit 32 as a protection signal to the signal output circuit 20. In other words, the output terminal of the NOR circuit 32 is connected to the other input terminal of the NOR circuit 31, and is also connected to the signal output circuit 20. The NOR circuit 32 inputs the protection signal to the other input terminal of the NOR circuit 31 and the signal output circuit 20.

[0055] In this example, the overcurrent protection circuit 22 is an RS flip-flop circuit. The current detection signal is input as a set signal of the RS flip-flop circuit. The control signal is input as a reset signal of the RS flip-flop circuit. The protection signal is the output signal (Q signal) of the RS flip-flop circuit.

[0056] FIG. 4 is a timing chart illustrating an example of the operation of the dimmer according to the embodiment. FIG. 4 shows an example of a control signal input from the signal generator 16 to the signal output circuit 20 and the overcurrent protection circuit 22, a signal input to the other input terminal of the NOR circuit 32 via the NOT gate 33 in the overcurrent protection circuit 22, a dimming signal output from the signal output circuit 20, a current detection signal input from the signal output circuit 20 to the overcurrent protection circuit 22, and a protection signal input from the overcurrent protection circuit 22 to the signal output circuit 20.

[0057] As shown in Figure 4, during a normal period when the current magnitude of the dimming signal is less than a threshold value, the dimming signal switches from a low voltage first state to a high voltage second state in response to the control signal switching from a low voltage third state to a high voltage fourth state (timing t1 in Figure 4).

[0058] During the normal period, in response to the control signal switching from the high-voltage fourth state to the low-voltage third state, the dimming signal switches from the high-voltage second state to the low-voltage first state (timing t2 in FIG. 4). This allows the dimming signal to switch between the third and fourth states according to the dimming level set by operation unit 18, thereby switching between the first and second states of the dimming signal and turning on lighting device 4 at a brightness according to the set dimming level.

[0059] The overcurrent protection circuit 22 configures peripheral circuits of the NOR circuit 31 so that, for example, during a normal period in which the current magnitude of the dimming signal is below a threshold, the voltage at one of the input terminals of the NOR circuit 31 that receives the current detection signal is in a low state (low voltage state), and during an abnormal period in which the current magnitude of the dimming signal is above the threshold, the voltage at one of the input terminals of the NOR circuit 31 that receives the current detection signal is in a high state (high voltage state).

[0060] In addition, during a normal period when the current of the dimming signal is less than the threshold, the overcurrent protection circuit 22 sets the voltage of the output terminal of the NOR circuit 32 that outputs the protection signal to a low state. In this case, during the normal period, the voltage of the other input terminal of the NOR circuit 31 is also in a low state. Therefore, during the normal period, the voltages of the pair of input terminals of the NOR circuit 31 are in a low state, and accordingly, the voltage of the output terminal of the NOR circuit 31 is in a high state.

[0061] During a normal period, the voltage of one input terminal of the NOR circuit 32 connected to the output terminal of the NOR circuit 31 is in a high state. Therefore, during a normal period, even if the voltage of the other input terminal of the NOR circuit 32 changes between a low state and a high state in response to a control signal, the voltage of the output terminal of the NOR circuit 32 is maintained in a low state.

[0062] When the control signal switches from the third state to the fourth state and the dimming signal switches from the first state to the second state, if the magnitude of the current of the dimming signal becomes equal to or greater than a threshold value, the voltage of one of the input terminals of the NOR circuit 31 that receives the current detection signal switches from a low state to a high state (timing t3 in Figure 4).

[0063] When the voltage at one of the input terminals of the NOR circuit 31 switches from a low state to a high state, the voltage at the output terminal of the NOR circuit 31 switches from a high state to a low state, and the voltage at one of the input terminals of the NOR circuit 32 also switches from a high state to a low state.

[0064] When the control signal is in the fourth state, the voltage of the other input terminal of the NOR circuit 32 is set to a low state by inverting the logic by the NOT gate 33. Therefore, when the magnitude of the current of the dimming signal becomes equal to or greater than the threshold value, the voltages of the pair of input terminals of the NOR circuit 32 both become low, and the voltage of the output terminal of the NOR circuit 32 switches from low to high (timing t4 in FIG. 4).

[0065] When the voltage of the output terminal of the NOR circuit 32 switches from a low state to a high state, a protection signal is input from the overcurrent protection circuit 22 to the signal output circuit 20. Inputting a protection signal from the overcurrent protection circuit 22 to the signal output circuit 20 is, in other words, switching the protection signal input from the overcurrent protection circuit 22 to the signal output circuit 20 from a low voltage state to a high voltage state.

[0066] In response to the protection signal input from the overcurrent protection circuit 22, the signal output circuit 20 stops outputting the dimming signal and sets the dimming signal to the first state (timing t4 in FIG. 4). In other words, in response to the protection signal input from the overcurrent protection circuit 22, the signal output circuit 20 switches the dimming signal from the second state to the first state. This allows an overcurrent protection operation to be performed during an abnormal period in which the current magnitude of the dimming signal is equal to or greater than a threshold value, thereby making it possible to suppress an overcurrent in the dimming signal. For example, it is possible to suppress a situation in which an overcurrent flows through the signal lines 6a and 6b, causing the dimmer 10 or the lighting fixture 4 to break down.

[0067] After the voltage at the output terminal of the NOR circuit 32 switches to a high state and an overcurrent protection operation is performed, the control signal switches from the fourth state to the third state and the voltage at the other input terminal of the NOR circuit 32 switches from a low state to a high state, and the voltage at the output terminal of the NOR circuit 32 switches from a high state to a low state, and the input of the protection signal is stopped (timing t5 in Figure 4).

[0068] Thus, in this example, when the overcurrent protection circuit 22 performs an overcurrent protection operation, the overcurrent protection circuit 22 stops the overcurrent protection operation by stopping the input of the protection signal to the signal output circuit 20 in response to the control signal switching from the fourth state to the third state.

[0069] After performing the overcurrent protection operation, if the current magnitude of the dimming signal again becomes equal to or greater than the threshold value in response to the control signal switching from the third state to the fourth state, the overcurrent protection operation is performed in the same manner (timing t6 in Figure 4).

[0070] In this way, in the dimmer 10, if the abnormal period continues, the overcurrent protection operation is performed in response to the control signal switching from the third state to the fourth state, and the overcurrent protection operation is stopped in response to the control signal switching from the fourth state to the third state, and the execution and stopping of the overcurrent protection operation is repeated in response to the switching of each state of the control signal.

[0071] As shown in FIG. 4, in the dimmer 10, an overcurrent is detected by the overcurrent protection circuit 22 from the time when the dimming signal switches from the first state to the second state in response to the control signal switching from the third state to the fourth state, and the dimming signal switches from the second state to the first state in response to the execution of the overcurrent protection operation, so that the dimming signal becomes the second state, which has a slightly higher voltage.

[0072] The time during which the dimming signal is in the second state can be set to a range that does not substantially affect the dimming degree, for example, by sufficiently increasing the operating speed of the signal output circuit 20 and the overcurrent protection circuit 22. For example, the time during which the dimming signal is in the second state can be set to a range of less than 1% of the dimming degree.

[0073] As a result, for example, in the case where the state in which one entire cycle of the dimming signal is in the first state is set to 100% dimming, if an abnormal period continues, the lighting device 4 can be made to recognize that the dimming level is set to 100% and the lighting device 4 can be turned on with a brightness of substantially 100%. Conversely, in the case where the state in which the dimming signal is in the first state is set to 0% dimming, if an abnormal period continues, the lighting device 4 can be made to recognize that the dimming level is set to 0% and the lighting device 4 can be turned off.

[0074] On the other hand, if, after performing the overcurrent protection operation, the magnitude of the current of the dimming signal falls below the threshold in response to the control signal switching from the third state to the fourth state, the overcurrent protection operation remains stopped, and the dimming signal is switched between the first and second states in response to the control signal, as described above, so that the lighting device 4 can be turned on at a brightness level corresponding to the set dimming level (timing t7 in Figure 4).

[0075] As described above, in the dimmer 10 of this embodiment, the overcurrent protection circuit 22 performs an overcurrent protection operation to stop the output of the dimming signal in response to detection of an overcurrent in the dimming signal, and when the overcurrent protection operation has been performed, stops the overcurrent protection operation in response to switching of the control signal from the fourth state to the third state.

[0076] As a result, in the dimmer 10 according to this embodiment, even when an overcurrent protection operation is performed, it is possible to reduce the trouble of requiring a user to perform a reset operation, such as turning the power of the dimmer 10 itself on and off.

[0077] Furthermore, in the dimmer 10 of this embodiment, for example, by prohibiting operation of the overcurrent protection function for a predetermined time from the timing of switching the dimming signal from the first state to the second state, it is not necessary to set a period for prohibiting operation of the overcurrent protection function, as in the case of suppressing operation of the overcurrent protection function due to a transient overcurrent, and delays in overcurrent protection can be suppressed.

[0078] Furthermore, unlike the case where the operation of the overcurrent protection function due to a transient overcurrent is suppressed, a timer circuit or the like is not required. For example, the overcurrent protection circuit 22 can be configured only with a relatively inexpensive logic circuit such as an RS flip-flop circuit as shown in FIG. 3 without requiring a relatively expensive component such as a microcomputer having a timer circuit. In the dimmer 10 according to this embodiment, the configuration of the dimmer 10 can be prevented from becoming complicated. For example, it can be prevented from requiring expensive components and from increasing the manufacturing cost of the dimmer 10.

[0079] In this way, the dimmer 10 according to this embodiment can provide overcurrent protection for the dimming signal more quickly with a simpler configuration, and can also reduce the effort required to release the overcurrent protection state.

[0080] In addition, in the dimmer 10 according to the present embodiment, when an overcurrent protection operation is performed due to a transient overcurrent caused by, for example, the floating capacitance of the signal lines 6a and 6b, the dimming function of the lighting fixture 4 is disabled and the lighting fixture 4 is turned on or off. This allows the user to recognize that the wiring conditions of the signal lines 6a and 6b are not appropriate. Similarly, when an overcurrent occurs due to an unintended load connection or a short circuit of the signal lines 6a and 6b, the lighting fixture 4 is turned on or off, allowing the user to recognize the occurrence of an abnormality.

[0081] In the dimmer 10 according to the present embodiment, the overcurrent protection operation can be automatically stopped by simply rewiring the signal lines 6a and 6b or reconsidering the connected load to eliminate the abnormal state, and the dimmer 10 and the lighting fixture 4 can be restored to normal operation without performing a reset operation such as turning the power on and off. In this way, in the dimmer 10 according to the present embodiment, even when an overcurrent occurs due to an abnormality in the load or the signal lines 6a and 6b, the dimmer 10 can be restored to normal operation while minimizing the effort required of the user.

[0082] FIG. 5 is a timing chart illustrating an example of another operation of the dimmer according to the embodiment. As shown in FIG. 5, in this example, when the overcurrent protection circuit 22 performs an overcurrent protection operation, the overcurrent protection circuit 22 stops the overcurrent protection operation by stopping the input of the protection signal to the signal output circuit 20 in response to the control signal switching from the third state to the fourth state (timing t11 in FIG. 5).

[0083] In this way, the overcurrent protection circuit 22 may stop the overcurrent protection operation in response to the switching of the control signal from the third state to the fourth state when the overcurrent protection operation has been performed. The configuration of the overcurrent protection circuit 22 is not limited to the configuration shown in Fig. 3, and may be any configuration that can perform an overcurrent protection operation to stop the output of the dimming signal in response to detection of an overcurrent in the dimming signal, and can stop the overcurrent protection operation in response to the switching of the control signal from the third state to the fourth state or from the fourth state to the third state when the overcurrent protection operation has been performed.

[0084] FIG. 6 is a block diagram illustrating a modified example of the dimmer according to the embodiment. 6, in the dimmer 10a, the operation unit 18 of the dimmer 10 according to the above embodiment is replaced with a communication unit 24. Note that parts that are substantially the same in function and configuration as those in the above embodiment are given the same reference numerals, and detailed description thereof will be omitted.

[0085] In this example, signal generator 16 is connected to a communication unit 24. Communication unit 24 communicates with an external device to receive an operation signal from the external device in response to an operation instruction regarding the dimming level of light emitted from lighting fixture 4. Communication unit 24 inputs the operation signal received from the external device to signal generator 16. In this example, signal generator 16 receives an input of the operation signal from communication unit 24.

[0086] The external device is, for example, a mobile terminal or a dedicated remote control. The mobile terminal is, for example, a smartphone or a tablet terminal owned by the user. The communication unit 24 receives an operation signal from the external device by, for example, performing wireless communication with the external device. However, the communication between the communication unit 24 and the external device is not limited to wireless communication and may be wired communication. The external device may be, for example, a higher-level controller that performs wired communication with the communication unit 24.

[0087] By operating an external device, the user receives an operation signal at communication unit 24 of dimmer 10a. Communication unit 24 inputs the operation signal received from the external device to signal generator 16. In this example, this allows lighting device 4 to emit light with a brightness that corresponds to the user's operation of the external device.

[0088] In this way, the signal generator 16 may receive an input of an operation signal from the operation unit 18, or may receive an input of an operation signal from the communication unit 24. For example, both the operation unit 18 and the communication unit 24 may be provided in the dimmer, and the signal generator 16 may receive an input of an operation signal from both the operation unit 18 and the communication unit 24. The configuration in which the signal generator 16 receives an input of an operation signal is not limited to the above, and any configuration may be used that allows the signal generator 16 to appropriately receive an input of an operation signal.

[0089] The present embodiment includes the following aspects. (Appendix 1) A dimmer that is connected to a lighting fixture via a pair of signal lines and transmits a dimming signal to the lighting fixture to change the brightness of light emitted from the lighting fixture, a signal generator that receives an operation signal corresponding to an operation instruction regarding a dimming level of the light emitted from the lighting device and generates a control signal for generating the dimming signal having a dimming level corresponding to the input operation signal; a signal output circuit having a pair of output terminals connected to the pair of signal lines, generating the dimming signal having a dimming level corresponding to the operation signal based on the control signal, outputting the generated dimming signal from the pair of output terminals, and detecting a current of the dimming signal; an overcurrent protection circuit that receives an input of a current detection signal representing a magnitude of a current of the dimming signal detected from the signal output circuit, detects an overcurrent of the dimming signal based on the current detection signal, and performs an overcurrent protection operation to cause the signal output circuit to stop outputting the dimming signal by inputting a protection signal to the signal output circuit in response to the detection of an overcurrent of the dimming signal; Equipped with the dimming signal is a pulse signal that alternates between a first state having a low voltage and a second state having a high voltage; the control signal is a pulse signal that alternately repeats a third state for setting the dimming signal to the first state and a fourth state for setting the dimming signal to the second state; The overcurrent protection circuit receives the current detection signal from the signal output circuit and the control signal from the signal generator, and when performing the overcurrent protection operation, stops the overcurrent protection operation by stopping the input of the protection signal to the signal output circuit in response to the control signal switching from the third state to the fourth state or from the fourth state to the third state.

[0090] (Appendix 2) an operation unit that receives an input of an operation instruction related to a dimming level of the light emitted from the lighting device and inputs the operation signal representing the dimming level according to the input operation instruction to the signal generator; The dimmer according to claim 1, wherein the signal generator receives the operation signal from the operation unit.

[0091] (Appendix 3) a communication unit that receives the operation signal corresponding to an operation instruction regarding a dimming level of the light emitted from the lighting device from the external device by communicating with the external device, and inputs the operation signal received from the external device to the signal generator; The dimmer according to claim 1 or 2, wherein the signal generator receives the operation signal from the communication unit.

[0092] (Appendix 4) A lighting fixture having a light source, illuminating a space by irradiating light from the light source, and having a dimming function for changing the brightness of the light irradiated from the light source; A dimmer according to any one of appendices 1 to 3, which is connected to the lighting fixture via a pair of signal lines and transmits a dimming signal to the lighting fixture to change the brightness of light emitted from the lighting fixture; A lighting system with.

[0093] Although some embodiments and examples of the present invention have been described, these embodiments or examples are presented as examples and are not intended to limit the scope of the invention. These novel embodiments or examples can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments or examples and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0094] 2...Lighting system, 4...Lighting fixture, 4a...Light source, 6a, 6b...Signal line, 10, 10a...Dimmer, 12...Conversion circuit, 14...Control power supply circuit, 16...Signal generator, 18...Operation unit, 20...Signal output circuit, 22...Overcurrent protection circuit, 24...Communication unit, 31, 32...NOR circuit, 33...NOT gate, PS...Power supply

Claims

1. A dimmer that is connected to a lighting fixture via a pair of signal lines and transmits a dimming signal to the lighting fixture to change the brightness of light emitted from the lighting fixture, a signal generator that receives an operation signal corresponding to an operation instruction regarding a dimming level of the light emitted from the lighting device and generates a control signal for generating the dimming signal having a dimming level corresponding to the input operation signal; a signal output circuit having a pair of output terminals connected to the pair of signal lines, generating the dimming signal having a dimming level corresponding to the operation signal based on the control signal, outputting the generated dimming signal from the pair of output terminals, and detecting a current of the dimming signal; an overcurrent protection circuit that receives an input of a current detection signal representing a magnitude of a current of the dimming signal detected from the signal output circuit, detects an overcurrent of the dimming signal based on the current detection signal, and performs an overcurrent protection operation to cause the signal output circuit to stop outputting the dimming signal by inputting a protection signal to the signal output circuit in response to the detection of an overcurrent of the dimming signal; Equipped with the dimming signal is a pulse signal that alternately repeats a first state having a low voltage and a second state having a high voltage, the control signal is a pulse signal that alternately repeats a third state for setting the dimming signal to the first state and a fourth state for setting the dimming signal to the second state, The overcurrent protection circuit receives the current detection signal from the signal output circuit and the control signal from the signal generator, and when performing the overcurrent protection operation, stops the overcurrent protection operation by stopping the input of the protection signal to the signal output circuit in response to the control signal switching from the third state to the fourth state or from the fourth state to the third state.

2. an operation unit that receives an input of an operation instruction related to a dimming level of the light emitted from the lighting device and inputs the operation signal representing the dimming level according to the input operation instruction to the signal generator; The dimmer according to claim 1 , wherein the signal generator receives the operation signal from the operation unit.

3. a communication unit that receives the operation signal corresponding to an operation instruction regarding a dimming level of the light emitted from the lighting device from the external device by communicating with the external device, and inputs the operation signal received from the external device to the signal generator; The dimmer according to claim 1 , wherein the signal generator receives the operation signal from the communication unit.

4. A lighting fixture having a light source, illuminating a space by irradiating light from the light source, and having a dimming function for changing the brightness of the light irradiated from the light source; The dimmer according to any one of claims 1 to 3, which is connected to the lighting fixture via a pair of signal lines and transmits a dimming signal to the lighting fixture to change the brightness of the light emitted from the lighting fixture; A lighting system with.

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