JP6941807B2 - Lighting device and lighting equipment - Google Patents

Description

The present invention relates to a lighting device capable of controlling a dimming level and a lighting fixture provided with the lighting device.

Conventionally, a luminaire capable of changing the brightness of illuminating light, that is, a luminaire capable of dimming is known (see, for example, Patent Document 1).

The luminaire described in Patent Document 1 detects a state of a semiconductor light emitting element and adjusts an operating point of a voltage-current characteristic of the semiconductor light emitting element according to an output of a dimming means to emit a plurality of solid-state lights. We are trying to suppress variations in illumination light intensity between elements.

Japanese Unexamined Patent Publication No. 2009-231147

However, in the luminaire described in Patent Document 1, the voltage detected for adjusting the operating point can be affected by noise. Therefore, when the control is performed based on the detection voltage affected by noise, the illumination light may flicker. In order to suppress the influence of such noise, it is conceivable to suppress the fluctuation of the detection voltage due to noise by integrating the detection voltage. However, in that case, the response of the control that changes the dimming level becomes slow.

Therefore, an object of the present invention is to provide a lighting device capable of suppressing flicker of illumination light from a light emitting element and having good responsiveness of dimming control, and a lighting fixture provided with the lighting device.

In order to achieve the above object, the lighting device according to one aspect of the present invention is a lighting device that supplies power to a light emitting element, is connected in series with the light emitting element, and controls a current flowing through the light emitting element. The light emitting element receives an instruction regarding a current circuit, a variable voltage source that supplies a variable DC voltage to the light emitting element and the constant current circuit, and a dimming level of the light emitting element, and the current corresponding to the received instruction is the light emitting element. The DC voltage is the variable voltage so that the constant current circuit is controlled so that the voltage drop in the light emitting element becomes a predetermined voltage based on the integrated value of the information related to the voltage drop in the light emitting element. A control circuit for controlling the variable voltage source so as to be output from the source is provided, and the control circuit changes the integration time of the integrated value according to the dimming level indicated by the instruction.

Further, in order to achieve the above object, the lighting equipment according to one aspect of the present invention includes the above lighting device and a light emitting element.

According to the present invention, it is possible to provide a lighting device capable of suppressing flicker of illumination light from a light emitting element and having good responsiveness of dimming control, and a luminaire including the lighting device.

FIG. 1 is a circuit diagram showing an example of a circuit configuration of a lighting device and a lighting fixture according to an embodiment. FIG. 2A is a flowchart showing control of the transistor Q2 by the control circuit of the lighting device according to the present embodiment. FIG. 2B is a flowchart showing control of the variable voltage source by the control circuit of the lighting device according to the embodiment. FIG. 3 is a graph showing an operation example of the lighting fixture according to the embodiment. FIG. 4 is a graph showing an operation example of the lighting fixture according to the comparative example. FIG. 5A is an external view of the lighting fixture according to the embodiment. FIG. 5B is an external view of another luminaire according to the embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that all of the embodiments described below show a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement of components, connection modes, etc. shown in the following embodiments are examples, and are not intended to limit the present invention. Therefore, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept of the present invention will be described as arbitrary components.

Further, each figure is a schematic view and is not necessarily exactly illustrated. Further, in each figure, the same components are designated by the same reference numerals.

(Embodiment)
The lighting device according to the embodiment and the lighting equipment provided with the lighting device will be described.

[1. Lighting equipment configuration]
The configuration of the lighting device and the lighting fixture according to the present embodiment will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing an example of a circuit configuration of a lighting device 10 and a lighting fixture 20 according to the present embodiment.

The lighting fixture 20 is a fixture that emits illumination light and has a dimming function. As shown in FIG. 1, the luminaire 20 includes a lighting device 10 and a light emitting element 5.

The light emitting element 5 is an element that receives an electric current and emits illumination light, and is, for example, an LED.

The lighting device 10 is a device that supplies electric power to the light emitting element 5. The lighting device 10 controls the dimming level of the light emitting element 5 based on the dimming signal. The lighting device 10 includes an input circuit 11, a rectifier circuit 12, a variable voltage source 15, a transistor Q2, a resistor R1, and a control circuit 16. Note that FIG. 1 also shows a dimmer 6 connected to the lighting device 10.

The dimmer 6 is a device that outputs a dimming signal instructing the dimming level to the lighting device 10 (more specifically, the control circuit 16). The dimmer 6 includes, for example, an input device such as a dial, a slider, an operation button, and a touch panel, a detection circuit that reads an instruction from the input device, a signal generation / output / communication circuit that outputs the instruction as a dimming signal by wire or wirelessly, and the like. Consists of.

The input circuit 11 is a circuit that receives AC power, and is composed of, for example, a connector connected to a system power source such as a commercial power source, a power filter, and the like.

The rectifier circuit 12 is a circuit that converts AC power into DC power, and is composed of a bridge diode or the like.

The variable voltage source 15 is a power source that supplies a variable DC voltage to the light emitting element 5 and the transistor Q2. The variable voltage source 15 boosts or steps down the DC voltage output from the rectifying circuit 12 to the DC voltage corresponding to the control signal input from the first control terminal 16a of the control circuit 16 and outputs the SEPIC (Single Ended Primery). Inductor Converter).

More specifically, the variable voltage source 15 is a switching power supply including a diode D1, inductors L1 and L2, capacitors C1, C2 and C3, and a transistor Q1.

The capacitor C1 is connected to the two output terminals of the rectifier circuit 12. One terminal of the inductor L1 is connected to the output terminal on the high potential side of the rectifier circuit 12, and the other terminal is connected to the drain electrode of the transistor Q1. One terminal of the capacitor C2 is connected to the drain electrode of the transistor Q1, and the other terminal is connected to one terminal of the inductor L2. One terminal of the inductor L2 is connected to the other terminal of the capacitor C2, and the other terminal is grounded. In the diode D1, the anode electrode is connected to the one terminal of the inductor L2, and the cathode electrode is connected to the output terminal on the high potential side of the lighting device 10. The capacitor C3 is an electrolytic capacitor, the positive electrode of the capacitor C3 is connected to the output terminal on the high potential side of the lighting device 10, and the negative electrode is grounded. The transistor Q1 is an element that switches (that is, repeats on and off) based on a signal output from the first control terminal 16a of the control circuit 16. In the present embodiment, the transistor Q1 is composed of an N-channel MOS (Metal-Oxide Semiconductor) type FET (Field-Effective Transistor).

The transistor Q2 is an example of a constant current circuit that is connected in series with the light emitting element 5 and controls the current flowing through the light emitting element 5, and is, for example, an N-channel MOS type FET. The transistor Q2 also functions as a dropper circuit that drops the voltage applied to the load (light emitting element 5) from the variable voltage source 15 due to the voltage drop (drain-source voltage Vds) generated here.

The resistor R1 is a protective resistance element. The resistance value of the resistor R1 is sufficiently smaller than the resistance value between the drain and the source of the transistor Q2.

The control circuit 16 is a circuit that controls the variable voltage source 15 and the transistor Q2 based on the dimming signal from the dimmer 6, and is realized by, for example, a microcomputer (microcomputer). A microcomputer is a one-chip semiconductor integrated circuit having a ROM in which a program is stored, a RAM, a processor (CPU) for executing the program, a timer, an input / output circuit including an A / D converter and a D / A converter, and the like. ..

More specifically, when the control circuit 16 receives an instruction (dimming signal) about the dimming level of the light emitting element 5 from the dimmer 6, the control circuit 16 performs the following two controls. That is, one controls the transistor Q2 so that the current corresponding to the received instruction flows through the light emitting element 5. The other is variable so that the DC voltage at which the voltage drop at the light emitting element 5 becomes a predetermined voltage is output from the variable voltage source 15 based on the integrated value of the information related to the voltage drop at the light emitting element 5. Control the voltage source 15. Further, the control circuit 16 changes the integration time of the integrated value of the information related to the voltage drop in the light emitting element 5 according to the dimming level indicated by the instruction.

Here, the control circuit 16 includes a first control terminal 16a connected to the control terminal (gate) of the transistor Q1 of the variable voltage source 15 and a second control terminal 16b connected to the control terminal (gate) of the transistor Q2. Has. The control circuit 16 controls the variable voltage source 15 via the first control terminal 16a so that the voltage drop at the transistor Q2 becomes a predetermined voltage. On the other hand, the control circuit 16 controls the transistor Q2 so that a current corresponding to an instruction (dimming signal) from the dimmer 6 flows through the light emitting element 5 via the second control terminal 16b.

[2. motion]
Next, the operation of the lighting device 10 according to the present embodiment configured as described above will be described. Here, the operation of the control circuit 16 that has received the instruction (dimming signal) from the dimmer 6 will be mainly described.

When the control circuit 16 receives an instruction (dimming signal) about the dimming level of the light emitting element 5 from the dimmer 6, the control circuit 16 performs the following two controls in parallel (or in order). That is, one controls the transistor Q2 so that the current corresponding to the received instruction flows through the light emitting element 5. The other is to control the variable voltage source 15 so that a DC voltage such that the voltage drop in the transistor Q2 becomes a predetermined voltage is output from the variable voltage source 15.

FIG. 2A is a flowchart showing control of the transistor Q2 by the control circuit 16 of the lighting device 10 according to the present embodiment.

When the control circuit 16 receives an instruction (dimming signal) about the dimming level from the dimmer 6 (S10), a current corresponding to the instruction (dimming signal) from the dimmer 6 flows through the light emitting element 5. As described above, the transistor Q2 is controlled via the second control terminal 16b (S11).

Specifically, the control circuit 16 stores a correspondence table between the instruction from the dimmer 6 and the voltage applied to the control terminal (gate) of the transistor Q2, and from the dimmer 6 according to the correspondence table. The voltage corresponding to the instruction of is applied to the control terminal (gate) of the transistor Q2.

By such control shown in FIG. 2A, a current corresponding to the instruction from the dimmer 6 flows through the light emitting element 5, and dimming control is performed.

FIG. 2B is a flowchart showing control of the variable voltage source 15 by the control circuit 16 of the lighting device 10 according to the present embodiment.

When the control circuit 16 receives an instruction (dimming signal) about the dimming level from the dimmer 6 (S20), the control circuit 16 determines whether or not the instruction is equal to or higher than a predetermined dimming level (S21).

As a result, when the instruction from the dimmer 6 is equal to or higher than the predetermined dimming level (Yes in S21), the control circuit 16 obtains the information related to the voltage drop in the light emitting element 5 in the first integration time. Integrate (S22).

More specifically, the control circuit 16 monitors the voltage Vds at the connection point between the light emitting element 5 and the transistor Q2 as information related to the voltage drop in the light emitting element 5. When the instruction from the dimmer 6 is equal to or higher than a predetermined dimming level, the control circuit 16 acquires an integrated value obtained by integrating the voltage Vds in the first integration time.

On the other hand, when the instruction from the dimmer 6 is less than the predetermined dimming level (No in S21), the control circuit 16 sets the information related to the voltage drop in the light emitting element 5 longer than the first integration time. Integrate in the second integration time (S23). That is, the integration time is longer when the dimming level indicated by the instruction from the dimmer 6 is less than the predetermined dimming level than when the dimming level is equal to or higher than the predetermined dimming level.

More specifically, when the instruction from the dimmer 6 is less than a predetermined dimming level, the control circuit 16 integrates the voltage Vds with a second integration time longer than the first integration time. Have acquired.

The predetermined dimming level described above may be a dimming level such that flicker caused by noise of the light emitting element 5 becomes inconspicuous, and is, for example, about 20%. Here, the dimming level value (%) is a value corresponding to the brightness, in which the full lighting (maximum brightness) is 100% and the extinguished state is 0%.

Further, the first integration time and the second integration time may be any time as long as the flicker of the light emitting element 5 can be suppressed.

Subsequently, the control circuit 16 controls the variable voltage source 15 so that the integrated value of the information related to the voltage drop in the light emitting element 5 becomes a predetermined voltage (S24). In the present embodiment, the control circuit 16 monitors the voltage Vds as information related to the voltage drop in the light emitting element 5, and performs feedback control on the transistor Q1 so that the voltage Vds becomes a predetermined voltage. do.

The control for the transistor Q1 is, for example, by changing the on-duty of the PWM signal given to the gate terminal of the transistor Q1, that is, by changing the on-time in one on-off cycle in the repeated on-off of the transistor Q1. Will be done.

Strictly speaking, the voltage Vds is the sum of the voltage drop in the transistor Q2 and the voltage drop in the resistor R1. However, since the resistance value of the resistor R1 is sufficiently smaller than the resistance value between the drain and the source of the transistor Q2, in the present embodiment, the control circuit 16 uses the transistor Q2 to set the voltage at the connection point between the light emitting element 5 and the transistor Q2. It is controlled by regarding it as a voltage drop of.

The method of setting the on-duty of the transistor Q1 in the control circuit 16 is not particularly limited, but the on-time Y of the transistor Q1 can be set by calculation as follows, for example.

_{Y = Y n-1 + α} 1 × E n + α 2 × E n-1 ( Equation 1)

_{Here, Y n-1} is the previous on-time applied to the transistor Q1, _{E n} is the current (or latest) the voltage _{Vds, E n-1} is the previous voltage Vds, alpha ₁ Represents a coefficient with respect to the current voltage Vds, and α ₂ represents a coefficient with respect to the past voltage Vds. By using the operation shown in Equation 1, for example, when α ₁ is large and α ₂ is small, the influence of the current voltage Vds becomes relatively large at the on-time Y. Therefore, this example corresponds to the case of using a relatively short integration time. On the other hand, when α ₁ is small and α ₂ is large, the influence of the past voltage Vds becomes relatively large at the on-time Y. Therefore, this example corresponds to the case of using a long integration time.

By using an on-time Y arithmetic expression as shown in Equation 1, the on-time Y corresponding to different integration times can be easily calculated.

Subsequently, an operation example of the lighting fixture 20 including the lighting device 10 according to the present embodiment will be described with reference to the drawings.

FIG. 3 is a graph showing an operation example of the lighting fixture 20 according to the present embodiment. The graph (a) of FIG. 3 shows an example of a voltage drop at the light emitting element 5, that is, a waveform of a forward voltage. Graphs (b) and (c) of FIG. 3 show the waveform of the gate voltage applied to the transistor Q1 and the waveform of the output voltage Vdc of the variable voltage source 15 corresponding to the graph (a), respectively. Has been done.

FIG. 4 is a graph showing an operation example of the lighting fixture according to the comparative example. The graph (a) of FIG. 4 shows an example of the waveform of the forward voltage of the light emitting element 5 which is the same as the graph (a) of FIG. The graphs (b1) and (c1) of FIG. 4 show the waveform of the gate voltage applied to the transistor Q1 and the waveform of the output voltage Vdc of the variable voltage source 15 corresponding to the graph (a), respectively. Has been done. Each waveform shown in the graph (b1) and the graph (c1) is a waveform when only the first integration time is used as the integration time of the voltage Vds used in the control circuit 16, respectively. The graphs (b2) and (c2) of FIG. 4 show the waveform of the gate voltage applied to the transistor Q1 and the waveform of the output voltage Vdc of the variable voltage source 15 corresponding to the graph (a), respectively. Has been done. Each waveform shown in the graph (b2) and the graph (c2) is a waveform when only the second integration time is used as the integration time of the voltage Vds used in the control circuit 16, respectively.

In the examples shown in the graph (b1) and the graph (c1) of FIG. 4, since the first integration time, which is relatively short, is used as the integration time of the voltage Vds, the response of the output voltage Vdc is fast. However, in this example, when the dimming level is less than 20%, the output voltage Vdc shown in the graph (c1) of FIG. 4 is caused by a minute fluctuation in the forward voltage shown in the graph (a) of FIG. Follows. Therefore, in the comparative example shown in the graph (c1), flicker occurs in the illumination light. The minute fluctuation of the forward voltage shown in the graph (a) of FIG. 4 is caused by ripples and noise included in the output voltage Vdc.

Further, in the examples shown in the graph (b2) and the graph (c2) of FIG. 4, since the second integration time, which is relatively long, is used as the integration time of the voltage Vds, the output is as shown in the graph (c2). No minute fluctuation occurs in the voltage Vdc. However, in this example, the response of the output voltage Vdc to the forward voltage is slow.

On the other hand, in the luminaire 20 according to the present embodiment, as shown in the graph (c) of FIG. 3, when the dimming level is less than 20%, minute fluctuations in the output voltage Vdc are suppressed. .. That is, even at the dimming level where flicker is easily noticeable, minute fluctuations in the output voltage Vdc are suppressed to the extent that flicker cannot be confirmed. Moreover, in the luminaire 20 according to the present embodiment, when the dimming level is 20% or more, the integration time of the voltage Vds is relatively short, so that the response to the forward voltage is relatively fast.

[3. summary]
As described above, the lighting device 10 according to the present embodiment is a lighting device 10 that supplies electric power to the light emitting element 5, is connected in series with the light emitting element 5, and controls the current flowing through the light emitting element 5. It includes a current circuit, a light emitting element 5, and a variable voltage source 15 that supplies a variable DC voltage to the constant current circuit. The lighting device 10 further receives an instruction regarding the dimming level of the light emitting element 5, controls a constant current circuit so that a current corresponding to the received instruction flows through the light emitting element 5, and causes a voltage drop in the light emitting element 5. A control circuit 16 for controlling the variable voltage source 15 is provided so that a DC voltage such that the voltage drop in the light emitting element 5 becomes a predetermined voltage is output from the variable voltage source 15 based on the integrated value of the information. The control circuit 16 changes the integration time of the integrated value according to the dimming level indicated by the instruction.

In such a lighting device 10, for example, in the control circuit 16, when the dimming level indicated by the instruction is 20% or more, the integration time is short and the dimming level is less than 20%. Can increase the integration time. Therefore, in the lighting device 10, it is possible to achieve both suppression of flicker of illumination light from the light emitting element 5 and good responsiveness of dimming control.

Further, in the lighting device 10, the integration time may be longer when the dimming level indicated by the instruction is less than the predetermined value than when it is equal to or more than the predetermined value.

As a result, in the lighting device 10, it is possible to suppress the flicker of the illumination light from the light emitting element 5 and to achieve good responsiveness of the dimming control.

Further, in the lighting device 10, the constant current circuit may include a transistor Q2.

This makes it possible to simplify the configuration of the lighting device 10.

Further, the lighting fixture 20 according to the present embodiment includes a lighting device 10 and a light emitting element 5.

As a result, the lighting fixture 20 can exert the same effect as the lighting device 10.

(others)
Hereinafter, specific examples, modifications, and the like of the lighting device 10 and the lighting fixture 20 according to the present embodiment will be described.

5A and 5B are external views of the lighting fixtures 20a and 20b according to the present embodiment, respectively.

The lighting fixture 20a shown in FIG. 5A is a downlight used for stage production and the like, and includes a circuit box 21a, a lamp body 22a, and a wiring 23. The circuit box 21a is a metal box that houses the lighting device 10 (not shown) according to the above embodiment. The lamp body 22a is an appliance to which an LED (not shown), which is a light emitting element 5, is mounted and is embedded and fixed in a ceiling or the like. The wiring 23 is a cable that electrically connects the lighting device 10 in the circuit box 21a and the LED in the lamp body 22a.

The lighting fixture 20b shown in FIG. 5B is a spotlight used for stage production and the like, and includes a circuit box 21b and a lamp body 22b. The circuit box 21b is a metal box that houses the lighting device 10 (not shown) according to the above embodiment, and is attached to a dedicated rail or the like. The lamp body 22b is an instrument equipped with an LED (not shown) which is a light emitting element 5.

Both of such lighting fixtures 20a and 20b include a light emitting element 5 and a lighting device 10 according to the above embodiment that supplies electric power to the light emitting element 5.

As a result, the lighting device 10 included in the lighting fixtures 20a and 20b has the same effect as the lighting device 10 described above. Therefore, flicker can be suppressed when the illumination light is used at an extremely low dimming level of 20% or less, which is required for stage production. Furthermore, the fast response required for stage production can be realized.

Although the lighting device 10 and the lighting fixtures 20a and 20b according to the present invention have been described above based on the embodiments, the present invention is not limited to the embodiments. As long as the gist of the present invention is not deviated, various modifications that can be conceived by those skilled in the art are applied to the present embodiment, and other embodiments constructed by combining some components in the embodiment are also within the scope of the present invention. Included in.

For example, in the above embodiment, the light emitting element 5 is an LED, but the light emitting element 5 is not limited to this, and may be another light emitting element such as an organic EL.

Further, in the above embodiment, the transistor Q2 is used as the constant current circuit in the lighting device 10, but the constant current circuit is not limited to this. For example, a variable resistor may be used as the constant current circuit.

Further, in the above embodiment, the lighting device 10 has an input circuit 11 and a rectifier circuit 12, but these are not always necessary. The lighting device 10 may be a power supply circuit that does not require these circuits, for example, that receives a DC voltage from a battery as an input.

Further, in the above embodiment, the variable voltage source 15 is SEPIC, but the present invention is not limited to this, and any DC voltage source capable of changing the output voltage according to a control signal from the outside is a linear regulator. It may be another voltage source such as.

Further, in the above embodiment, a protective resistor R1 is used for the lighting device 10, but this resistor R1 is not always necessary and may not be mounted according to the required specifications.

Further, in the above embodiment, the control circuit 16 is realized by software by a microcomputer having a program. However, the method is not limited to this, and may be realized in terms of hardware by a dedicated electronic circuit composed of an A / D converter, a logic circuit, a gate array, a D / A converter, and the like.

Further, in the above embodiment, in the control circuit 16, only the first integration time and the second integration time are used, but different integration times may also be used. For example, an integration time that is inversely proportional to the dimming level may be used.

Further, in the above embodiment, the lighting fixtures 20a and 20b are downlights and spotlights, but the lighting fixtures are not limited to these types, and other types of lighting such as ceiling lights, chandeliers, pendant lights, and footlights. It may be an instrument.

In addition, it is realized by arbitrarily combining the components and functions in each embodiment within the range obtained by applying various modifications to each embodiment and the gist of the present invention. Forms are also included in the present invention.

5 Light emitting element 10 Lighting device 15 Variable voltage source 16 Control circuit Q2 Transistor (constant current circuit)

Claims (3)

A lighting device that supplies electric power to a light emitting element.
A constant current circuit that is connected in series with the light emitting element and controls the current flowing through the light emitting element.
A variable voltage source that supplies a variable DC voltage to the light emitting element and the constant current circuit,
Upon receiving an instruction regarding the dimming level of the light emitting element, the constant current circuit is controlled so that the current corresponding to the received instruction flows through the light emitting element, and an integrated value of information relating to a voltage drop in the light emitting element. Based on the above, a control circuit for controlling the variable voltage source so that the DC voltage such that the voltage drop in the light emitting element becomes a predetermined voltage is output from the variable voltage source is provided.
The control circuit changes the integration time of the integrated value according to the dimming level indicated by the instruction .
A lighting device in which the integration time is longer when the dimming level indicated by the instruction is less than the predetermined value and when it is equal to or more than the predetermined value. The lighting device according to claim 1, wherein the constant current circuit includes a transistor. The lighting device according to claim 1 or 2,
A lighting fixture including the light emitting element.

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