JP2018055785A - Lighting equipment and lighting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide lighting equipment which makes a luminous color unlikely to be changed by a current value supplied to a light-emitting diode or a duty cycle of PWM control, and a lighting apparatus.SOLUTION: Lighting equipment comprises: a power conversion part which supplies a current and turns on a light-emitting element; a switch for making intermittent the current that flows to the light-emitting element; and a dimming control part which generates a PWM signal based on a dimming signal for setting lightness of the light-emitting element, and makes the switch intermittent in accordance with the PWM signal. The PWM signal includes an ON period in which the current is made flow, and an OFF period in which the current is cut off. The ON period and the OFF period are set in such a manner that a light emission wavelength of the light-emitting element is fixed for each level of the set lightness of the light-emitting element.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a lighting fixture and a lighting device.

  A lighting fixture using a semiconductor light emitting element such as a light emitting diode can easily perform dimming control by intermittently supplying a current supplied to the light emitting diode and adjusting a duty cycle. In addition, color rendering control can be easily performed by combining a plurality of colored light emitting diodes and performing dimming control on each.

  In the case of PWM control of a light emitting diode, it is known that the emission color changes depending on the waveform of the current flowing through the light emitting diode and the duty cycle. It is also known that the change in emission color differs depending on the wavelength of light emission of the light emitting diode.

Japanese Patent No. 5760176

  Embodiments provide a lighting apparatus and a lighting device that hardly cause a change in emission color depending on a current value supplied to a light emitting diode and a duty cycle of PWM control.

  The lighting fixture according to the embodiment is based on a power conversion unit that supplies current to turn on the light emitting element, a switch that intermittently switches the current flowing through the light emitting element, and a dimming signal that sets the brightness of the light emitting element. A dimming control unit that generates a PWM signal and switches the switch according to the PWM signal; The PWM signal includes an on period in which the current flows and an off period in which the current is interrupted. The on period and the off period are set so that the light emission wavelength of the light emitting element is constant for each set brightness of the light emitting element.

  In this embodiment, a dimming control unit that generates a PWM signal that is set so that the light emission wavelength of the light emitting element is constant for each brightness of the light emitting element in which the on period and the off period are set by the dimming signal. Since it is provided, the change in the emission color of the light emitting element can be reduced.

It is a block diagram which illustrates the lighting fixture which concerns on 1st Embodiment. It is a schematic diagram for demonstrating the operation principle of the lighting fixture of 1st Embodiment. It is a schematic diagram for demonstrating the operation principle of the lighting fixture of 1st Embodiment. It is a block diagram which illustrates the illuminating device which concerns on 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described 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 the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
In the present specification and drawings, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1 is a block diagram illustrating a lighting fixture according to this embodiment.
As shown in FIG. 1, the lighting fixture 10 of the present embodiment includes a power conversion unit 12, a lighting module 14, a dimming control unit 16, and a switch 18.

  The lighting fixture 10 includes power supply terminals 11a and 11b. The luminaire 10 is connected to the input power source 1 via the power terminals 11a and 11b. The input power source 1 is, for example, a commercial AC power source. The luminaire 10 is turned on when AC power is supplied from the input power supply 1.

  The lighting fixture 10 includes a dimming signal terminal 11c. The luminaire 10 inputs a dimming signal from a dimming device (not shown) via the dimming signal terminal 11c. The dimming signal is a signal for setting the brightness of the lighting module 14, and the lighting fixture 10 is lit with the brightness set by the input dimming signal.

  The power conversion unit 12 is connected between the power supply terminals 11 a and 11 b and the illumination module 14. The power converter 12 receives AC power from the input power supply 1 through the power terminals 11a and 11b. The power conversion unit 12 converts the input AC power into DC power and turns on the lighting module 14.

  The power conversion unit 12 includes, for example, a rectifying / smoothing circuit 121 and a DC-CD converter 122. The rectifying / smoothing circuit 121 converts an AC voltage into a DC voltage and supplies the DC voltage to the DC-DC converter 122. The rectifying / smoothing circuit 121 may include an active smoothing filter. The DC-DC converter 122 converts the DC voltage supplied from the rectifying / smoothing circuit 121 into a substantially constant DC current and supplies it to the illumination module 14. The current output from the DC-DC converter 122 is set in advance, for example. The DC-DC converter 122 outputs a preset current Io and supplies it to the lighting module 14. The DC-DC converter 122 only needs to be able to output a set direct current, regardless of whether it is a switching type or a linear type. The type of the DC-DC converter 122 is appropriately selected according to the input / output voltage and the output power.

  The illumination module 14 includes a light emitting element 15. A plurality of light emitting elements 15 are connected in series, for example. The light emitting element 15 is, for example, a light emitting diode. The light emission color of the light emitting diode is arbitrarily set. Further, as will be described later, the light emitting diode blinks in an on period and an off period according to the emission wavelength. Since the PWM control cycle, which is the sum of the on period and the off period, is sufficiently higher than the frequency that can be visually recognized by humans, the light-emitting diodes according to the on-duty set in the on-period and off-period are for human eyes. It appears to be lit at brightness.

  The dimming control unit 16 converts the dimming signal input via the dimming signal terminal 11c into a PWM signal and outputs the PWM signal. The dimming control unit 16 includes a table 17. As will be described in detail later, the table 17 is configured to supply a current to the lighting module 14 during a period (on period) in which the current is supplied to the lighting module 14 for each dimming degree (brightness of the lighting module 14) corresponding to the dimming signal. A time (off period) Toff during which no current flows is set. That is, the ON period Ton and the OFF period Toff are associated with each dimming degree set and stored in the table 17.

  The switch 18 is connected to the lighting module 14 in parallel. The switch 18 has a control terminal 18 a, and the control terminal 18 a is connected to the output of the dimming control unit 16. The switch 18 is opened and closed according to the PWM signal input to the control terminal 18a.

  The switch 18 is connected in parallel to the illumination module 14 and supplied with the current Io from the power conversion unit 12. When the switch 18 is opened, all of the current Io output from the power converter 12 flows to the lighting module 14. When the switch 18 is closed, all the current Io output from the power conversion unit flows to the switch 18. Therefore, the current IPWM flowing through the illumination module 14 becomes a pulse according to the opening / closing of the switch 18, and the light emission of the light emitting element 15 also becomes a pulse. By making the switching frequency of the switch 18 sufficiently higher than the frequency characteristic of human vision, pulsed light emission is perceived as having a brightness close to the average value over the pulse blinking cycle. That is, the brightness of the illumination module 14 is controlled by PWM control.

Operation | movement of the lighting fixture of this embodiment is demonstrated.
2 and 3 are schematic views for explaining the operation of the lighting fixture of the present embodiment.
The upper diagram in FIG. 2 shows a waveform of a current flowing through the illumination module when the dimming degree is large. In the lower diagram, a waveform of a current flowing through the illumination module when the dimming degree is small is shown. A period during which current flows through the illumination module 14 is referred to as an on period Ton, and a period during which no current flows through the illumination module 14 is referred to as an off period Toff.

  As shown in FIG. 2, the current flowing through the lighting module 14 has a rise time tr and a fall time tf corresponding to the response speed because the response speed of the output voltage of the power converter 12 is limited. The rise time tr and the fall time tf depend on the response characteristics of the output voltage of the power converter 12 and are substantially constant regardless of the on period Ton.

  As shown in the upper diagram of FIG. 2, the current waveform in the on period Ton has a trapezoidal shape when the on period is longer than the rising time tr and the falling time tf. When a trapezoidal current waveform is converted into a square wave, an average value may be taken over the on period Ton, which is as indicated by a dashed line in the figure. The current value of the alternate long and short dash line converted into a square wave is I1.

  As shown in the lower diagram of FIG. 2, the current waveform in the on period Ton becomes a triangular waveform as shown by a broken line as the upper side of the trapezoid becomes shorter as the on period Ton becomes shorter. The square wave converted current value is I2. I2 is a value smaller than I1. In the case of a triangular wave like a broken line, the average current over the ON period Ton is further reduced.

  Thus, the shorter the on-period Ton, the smaller the current value when converted to a square wave, and when the PWM period (Ton + Toff) is constant, the actual on-duty Don (= Ton / (Ton + Toff) ), A current IPWM having a current value lower than the current value according to FIG.

  In the light emitting diode, the emission wavelength changes depending on the flowing current. For example, it is known that a green light emitting diode using GaP, AlGaInP, or the like has a shorter wavelength as a flowing current value is smaller. A blue light emitting diode or a red light emitting diode using GaP, AlGaAs or the like also has a shorter wavelength as the flowing current is smaller. A short wavelength causes a color shift in which the emission color changes.

  In other words, if the on-duty Don is reduced when the illumination module 14 using the light-emitting diode as a light source is dimmed by PWM control with a constant period, the emission color is shifted to the short wavelength side. The degree of color shift varies depending on the material of the light emitting diode and the like, and the green light emitting diode tends to have a larger color shift than the other light emitting colors.

FIG. 3 shows a current waveform when the on-duty Don is changed when the current waveform flowing through the illumination module 14 is in the on period Ton that is sufficiently longer than the rise time tr and the fall time tf.
The upper diagram in FIG. 3 shows a current waveform when the on period Ton and the off period Toff are substantially equal.
The lower diagram of FIG. 3 shows a current waveform when the off period Toff is doubled when the on period Ton is the same as the upper diagram.

  As shown in FIG. 3, when the on period Ton is constant, the on duty Don can be controlled by changing the off period Toff. In the upper diagram of FIG. 3, the on-duty Don is approximately 50%, and in the lower diagram, the on-duty Don is lower than the upper diagram and is approximately 25%.

  Here, when the light source of the illumination module 14 is a light emitting diode, the light emission wavelength of the light emitting diode is also dependent on the on-duty Don.

  For example, it is known that a green light emitting diode or blue diode using GaP, AlGaInP, or the like has a longer wavelength as the on-duty Don is smaller. On the other hand, in the case of a red light emitting diode using GaP, AlGaAs or the like, the wavelength becomes shorter as the on-duty Don is smaller.

  In the example of FIG. 3, in the case of a green or blue light emitting diode, when the on-duty Don is lowered from the state of the upper diagram to the state of the lower diagram, the emission wavelength is shifted to the short wavelength side.

  In the case of a red light emitting diode, when the on-duty Don is lowered from the state of the upper diagram to the state of the lower diagram, the emission wavelength is shifted to the longer wavelength side.

  As described above, when a light emitting diode is used as the light source, when the current IPWM flowing through the illumination module 14 is controlled by a PWM signal having a certain period (reciprocal of the carrier frequency), the current IPWM is caused by the waveform. The effective current value changes. As the current value changes, the light emission wavelength of the light emitting diode shifts, causing a color shift. Here, the effective current value is, for example, a value obtained by averaging the current IPWM over the ON period Ton.

  Further, even when light control is performed by changing the off period Toff, the light emission wavelength of the light emitting diode is shifted by the on-duty Don, resulting in a color shift. The direction and extent of these color shifts differ depending on the material of the light emitting diode and the light emission color. That is, when the waveform of the current flowing through the light-emitting diode is set and an effective current value is set for each on-period Ton, the on-period Ton and the off-period Toff are less likely to cause a color shift depending on the light-emitting diode. Will exist.

  In the lighting fixture 10 of this embodiment, the light control part 16 has the table 17 which set the optimal ON period Ton and OFF period Toff with respect to the light control degree.

  The table 17 stores dimming degree data set corresponding to the dimming signal. The dimming degree data is stored, for example, by setting the brightness of the illumination module 14 in a range of 0% to 100% in a plurality of stages. For example, the dimming data is set in increments of 5% such as 0%, 5%, 10%,.

  In the table 17, data of the on period Ton and the off period Toff are stored in association with each of the dimming degree data. The data of the on period Ton and the off period Toff with respect to the light control data is set so as not to cause a light emission wavelength shift of the light emitting diodes to be lit.

  For example, in the case of a green light emitting diode, the smaller the current value and the longer the off period, the more the color shift occurs on the short wavelength side. Therefore, after acquiring the relationship between the current value and the wavelength shift and the relationship between the off period and the wavelength shift, the appropriate on period Ton and off period Toff are set.

  When the dimming signal is supplied from a dimming device (not shown), the dimming control unit 16 extracts the dimming degree (brightness) data included in the dimming signal and searches the table 17 for the corresponding dimming degree data. To do. The searched dimming degree data is associated with an on period Ton and an off period Toff suitable for the dimming degree. The dimming control unit 16 drives the switch 18 in the on period Ton and the off period Toff according to the dimming degree data.

The effect of the lighting fixture of this embodiment is demonstrated.
In the lighting device of the present embodiment, data of the on period Ton and the off period Toff set in accordance with the dimming degree are acquired in advance, and the data of the dimming degree and the data of the on period Ton and the off period Toff associated therewith are obtained. Therefore, it is possible to make it difficult for color deviation of the illumination module 14 driven by PWM control to occur.

(Second Embodiment)
A lighting device having a color rendering function can be realized by providing power conversion units for lighting the light emitting diodes in the number corresponding to the number of emitted colors.
FIG. 4 is a block diagram illustrating a lighting device of this embodiment.
As shown in FIG. 4, the illuminating device 110 of this embodiment is equipped with lighting fixture 10R, 10G, 10B. The lighting fixture 10R includes a lighting module 14R using a red light emitting diode as a light emitting element. The lighting fixture 10G includes a lighting module 14G having a green light emitting diode as a light emitting element. The lighting fixture 10B includes a lighting module 14B that uses a blue light emitting diode as a light emitting element. The configurations of the lighting fixtures 10R, 10G, and 10B are the same as those in the first embodiment.

  The lighting fixtures 10R, 10G, and 10B include dimming control units 16R, 16G, and 16B having tables 17R, 17G, and 17B that can appropriately dim red, green, and blue light emitting diodes, respectively.

  The tables 17R, 17G, and 17B have optimum on periods and off periods that are associated with the dimming levels of the respective light emitting diodes. Therefore, the light emitting diodes of the respective colors can emit light without causing a wavelength shift according to the dimming degree set for performing the toning and color rendering.

  According to the embodiment described above, it is possible to realize a lighting fixture that hardly causes a change in emission color depending on the waveform of the current supplied to the light emitting diode and the duty cycle of PWM control.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalents thereof. Further, the above-described embodiments can be implemented in combination with each other.

  DESCRIPTION OF SYMBOLS 1 AC power supply, 2 Dimming device, 10, 10R, 10G, 10B Lighting fixture, 11a, 11b Power supply terminal, 11c Dimming signal terminal, 12 Power conversion part, 14 Lighting module, 15 Light emitting element, 16 Dimming control part, 18 switch, 110 lighting device, 121 rectification smoothing circuit, 122 DC-DC converter

Claims (5)

A power conversion unit for lighting the light emitting element by supplying current;
A switch for intermittently passing a current flowing through the light emitting element;
A dimming control unit that generates a PWM signal based on a dimming signal that sets the brightness of the light emitting element and switches the switch according to the PWM signal;
With
The PWM signal includes an on period in which the current flows and an off period in which the current is cut off.
The lighting apparatus set so that the light emission wavelength of the light emitting element is constant for each set brightness of the light emitting element during the on period and the off period.   The lighting fixture according to claim 1, wherein a sum of the on period and the off period has different values over different brightnesses of the light emitting elements. The emission wavelength changes according to the value of the current in square wave conversion over the ON period,
The lighting apparatus according to claim 1, wherein the on period and the off period are set so as to cancel the change in the emission wavelength.   The luminaire according to claim 1, wherein the dimming control unit includes a table including the set brightness and the on period and the off period associated with the brightness. . A first power converter for supplying a first current to light the first light emitting element;
A first switch for intermittently passing a current flowing through the first light emitting element;
A first dimming control unit configured to generate a first PWM signal based on a first dimming signal for setting brightness of the first light emitting element and to intermittently switch the first switch according to the first PWM signal;
A first lighting fixture comprising:
A second power converter for supplying a second current to light the second light emitting element;
A second switch for intermittently passing a current flowing through the second light emitting element;
A second dimming control unit configured to generate a second PWM signal based on a second dimming signal that sets the brightness of the second light emitting element, and to switch the second switch according to the second PWM signal;
A second lighting fixture comprising:
With
The first PWM signal includes a first on period in which the first current flows and a first off period in which the first current is interrupted.
The first on-period and the first off-period are set so that the emission wavelength of the first light-emitting element is constant for each set brightness of the first light-emitting element,
The second PWM signal includes a second on period in which the second current flows and a second off period in which the second current is interrupted.
The second on-period and the second off-period are set so that the emission wavelength of the second light-emitting element is constant for each set brightness of the second light-emitting element,
The second on period and the 2 off period set for each brightness of the second light emitting element are the first on period and the first off period set for each brightness of the first light emitting element. Lighting equipment set independently.

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