JP5626840B2 - Lighting device - Google Patents

Description

  The present invention includes a plurality of light sources including light emitting elements that emit light when supplied with a direct current, and can control the light output of the light sources by controlling the direct current supplied to the plurality of light sources. Relates to the device.

  Various lighting fixtures are provided that include a light source that includes a light emitting element that emits light when supplied with a direct current (for example, an organic EL (Electro Luminescence) element, an LED (Light Emitting Diode), or the like). Some of these lighting fixtures perform dimming control of a light source by combining analog control and PWM (Pulse Width Modulation) control in order to expand the range in which dimming can be performed with high accuracy.

  Patent Documents 1 and 2 aim to provide a luminaire that can suppress flickering of the light source near the lower limit of the light output. When the light output setting of the light source exceeds a specified value, dimming is performed by PWM control. There is disclosed an illumination device that performs light control by analog control with a duty ratio of a PWM signal applied to the PWM control unit being 100% when controlled and below a specified value.

  Patent Document 3 aims to adjust the light output accurately to a low dimming level, and when the set dimming level changes within a specified value range or more, the amplitude value of the drive current and the duty ratio An illumination device is disclosed that adjusts the light output of a light-emitting module by changing one of the light-adjusting levels by fixing only one of the other and changing the other dimming level when the set dimming level changes within a specified value or less. ing. Dimming is the adjustment of the light output of the light source, and the dimming level means the magnitude of the light output of the light source indicated in the dimming.

JP 2008-210536 A JP 2008-210537 A JP 2009-054425 A

  In the control method in which analog control is performed at a low dimming level shown in Patent Document 1 or 2, when there are a plurality of light sources, due to variations in characteristics of a power supply, a drive circuit, and the like that supply a drive current to the light sources. Even if the light control level to be set is the same, a difference in light output occurs between the light sources. In particular, since the light output of the light source changes due to a slight difference in current value at a low dimming level near the start of lighting or near extinguishing, the light output of the light source is controlled with high accuracy in the control disclosed in Patent Document 1 or 2. It is difficult. For this reason, even when a plurality of light sources are turned on or off by changing the dimming level in the same manner, the time that can be recognized as turned on or off due to the difference in light output between the light sources (hereinafter, There is a problem that the “lighting and extinguishing timing” is abbreviated between the light sources.

  Patent Document 3 aims to expand the range in which dimming can be performed with high accuracy with respect to one light source. There is no description regarding a plurality of light sources, and even if the dimming level to be set is the same, the light output between the plurality of light sources is not described. There is no description or suggestion about the awareness of the problem that differences arise, which may cause the timing of turning on and off between light sources to vary.

  As described above, when a plurality of light sources are used for a lighting fixture that combines analog control and PWM control to expand the range of dimming with high accuracy, the timing of turning on and off each light source varies. Has not been recognized, and no attempt has been made to eliminate the variation. Hereinafter, the lighting fixture will be referred to as a lighting device.

  An object of the present invention is to provide an illuminating device that can suppress variations in lighting and extinguishing timings between light sources for an illuminating device having a plurality of light sources.

The lighting device according to the present invention includes:
A plurality of light sources composed of light emitting elements that emit light by energizing current;
A dimming level setting unit that sets the same dimming level at a common timing for the plurality of light sources;
When the set dimming level is less than a predetermined level with respect to the current flowing through the light source, the amplitude value of the current is fixed to a predetermined value, and the duty ratio of the current is set When the set dimming level is equal to or higher than the predetermined level, the duty ratio is fixed to 100%, and the amplitude value is set to the set dimming level. A dimming control unit that determines the value changed according to the level;
A drive unit configured to supply current supplied to each light source as a drive current having an amplitude value proportional to the determined amplitude value and the determined duty ratio;
Equipped with a,
The plurality of light sources are divided into a plurality of light source groups, and the light sources belonging to each light source group are of the same type,
One dimming control unit is provided for each light source group.

  According to the illuminating device according to the present application, it is possible to suppress variations in the timing of turning on and off between a plurality of light sources.

It is a block diagram which shows the structural example of the illuminating device which concerns on Embodiment 1 of this invention. (A) It is a figure which shows the relationship between the light control level which concerns on Embodiment 1, and the amplitude value of an analog control signal. (B) It is a figure which shows the relationship between the light control level which concerns on Embodiment 1, and the duty ratio of a PWM control signal. It is a block diagram which shows the structural example of the illuminating device which concerns on the other modification of Embodiment 2. FIG.

(Embodiment 1)
In the first embodiment, for a lighting device including a plurality of light sources, for example, a light control level input by a user is received, and the same light control level is set at a common timing for the plurality of light sources. When the input dimming level is less than a predetermined value (hereinafter referred to as switching dimming level), the light output of the light source is adjusted and controlled by PWM control when the dimming level is lower than the switching dimming level. It is characterized by combining a current control method of performing dimming control.

  FIG. 1 is a block diagram illustrating a configuration example of a lighting apparatus according to Embodiment 1. As illustrated in FIG. 1, the lighting device 1 includes a plurality of light sources 2, a dimming level setting unit 3, a dimming control unit 4, and a driving unit 5. The light control unit 4 and the drive unit 5 are provided for each light source 2. The dimming control unit 4 includes an analog control unit 41 and a PWM control unit 42, and the drive unit 5 includes a DC power supply unit 51, a drive circuit 52, and a switching circuit 53.

  The light source 2 includes one or more light emitting elements such as an LED and an organic EL element that emit light upon receiving a current (referred to as a driving current). Yes. The plurality of light sources 2 may be installed at different locations, or may be installed at the same location. In FIG. 1, one light source is represented by a symbol of one light emitting element.

  The dimming level setting unit 3 is installed as common to a plurality of light sources 2 and has an input function of turning on and off the light source 2 and a dimming level, and at the input lighting, extinguishing and dimming levels. Correspondingly, a turn-on signal, a turn-off signal, and a dimming signal are generated and output to each dimming control unit 4 at a common timing. The lighting, extinguishing, and dimming level are input by rotating or sliding the switch, for example. As shown in FIG. 1, the dimming signal uses a pulse signal having a predetermined frequency, for example, 1 kHz, and the pulse width L, that is, the duty ratio is made to correspond to the inputted dimming level. The dimming signal may be dimming data that is data obtained by digitizing the dimming level.

  The dimming control unit 4 performs analog control via the analog control unit 41 and the PWM control unit 42 when the dimming level specified by the dimming signal is equal to or higher than the switching dimming level, and less than the switching dimming level. In this case, PWM control is performed. Specifically, the dimming control unit 4 receives the input dimming signal, and sends the analog control signal and PWM to the drive circuit 52 of the drive unit 5 via the analog control unit 41 and the PWM control unit 42, respectively. A control signal A is output (see FIG. 1). The analog control signal is a signal having amplitude information, and the PWM control signal A is a signal having duty ratio information, which is a pulse train.

  FIG. 2A is a diagram illustrating the relationship between the light control level and the amplitude value of the analog control signal according to the first embodiment. FIG. 2B is a diagram illustrating the relationship between the light control level and the duty ratio of the PWM control signal A according to the first embodiment.

  As shown in FIG. 2A, the analog control unit 41 increases the amplitude value of the analog control signal according to the dimming level when the dimming level is equal to or higher than a predetermined dimming level (switching dimming level). When it is less than the switching dimming level, the amplitude is fixed to the amplitude at the switching dimming level.

  As shown in FIG. 2B, the PWM control unit 42 fixes the duty ratio to 100% when the dimming level is equal to or higher than the switching dimming level, and sets the duty ratio when the dimming level is lower than the switching dimming level. Decrease according to the dimming level.

  In actual operation, the diagrams shown in FIGS. 2A and 2B are tabulated, for example, and the analog control unit 41 and the PWM control unit 42 obtain the amplitude value and the duty ratio by referring to this table.

  The drive unit 5 supplies a predetermined drive current to the light source 2 via the DC power supply unit 51, the drive circuit 52, and the switching circuit 53 that are connected in series with each other according to the control of the dimming control unit 4. The light source 2 is driven to cause the light source 2 to emit light.

  The DC power supply unit 51 supplies a direct current to the light source 2 as a drive current. The DC power supply unit 51 does not need to have a power supply itself, and may have any function that converts a current supplied from an external power supply into a DC. For example, when alternating current is converted into direct current by combining an alternating current power supply and a rectifier circuit, the alternating current power supply may be an external power supply, and the direct current power supply unit 51 may be a rectifier circuit. Alternatively, the DC power supply unit 51 itself may be shared by a plurality of light sources 2 and excluded from the drive unit 5 and handled as an external power supply.

  The drive circuit 52 receives the analog control signal and the PWM control signal A, generates a PWM control signal B having a predetermined frequency having an amplitude value and a duty ratio determined by each control signal, and outputs the PWM control signal B to the switching circuit 53.

  The switching circuit 53 controls the opening / closing of the electric circuit from the DC power supply unit 51 to the light source 2 and the amplitude value of the drive current supplied to the light source 2 by the input of the PWM control signal B. Specifically, the switching circuit 53 is configured by a switching element such as an FET. The source of the FET is connected in series with the light source 2 and the output terminal of the DC power supply unit 51, the drive circuit 52 is connected to the gate of the FET, and the PWM control signal B is input. The drain current is controlled by the PWM control signal B input to the gate, has the same duty ratio as the PWM control signal B, and has a current amplitude proportional to the amplitude of the PWM control signal B. It becomes. This drain current is supplied to the light source 2 as a drive current (see FIG. 1). Therefore, the drive current of the light source 2 is controlled by analog control when the dimming level is higher than the switching dimming level, and by PWM control when the dimming level is lower than the switching dimming level.

  Next, the operation will be described. The dimming level setting unit 3 is connected to the dimming control unit 4 of each light source 2 as common to the plurality of light sources 2. Therefore, the dimming level input to the dimming level setting unit 3 is output as a dimming signal to the dimming control unit 4 provided for each light source 2 at a common timing. Therefore, the dimming control unit 4 of each light source 2 inputs the same dimming signal at a common timing. After the dimming control unit 4 inputs the dimming signal, as described above, when the dimming level specified by the dimming signal is equal to or higher than the switching dimming level, the analog control method is used, and when the dimming level is lower than the switching dimming level. The drive current controlled by the PWM control method is supplied to the light source 2.

  In the analog control method for controlling the current amplitude, the amplitude value of the drive current varies for each light source due to variations in characteristics of the power source, drive circuit, etc. that supply the drive current to the light source 2. Therefore, the variation in light output for each light source becomes significant for a predetermined dimming level, particularly a low dimming level. On the other hand, in the PWM control method, since the duty ratio is controlled instead of the amplitude control, such a variation hardly occurs. Therefore, a common dimming level setting unit 3 is provided for a plurality of light sources 2, and the same dimming signal is output to the dimming control unit 4 installed for each light source 2 at a common timing, When the dimming level is lower than the switching dimming level, the drive current is controlled by PWM control. This reduces the difference in light output between the light sources 2 that becomes significant when the dimming level is low. As a result, variations in lighting timing and lighting timing between the light sources 2 are also reduced.

  The dimming control method is switched between the two methods in order to expand the range in which dimming can be performed with high accuracy. Since it is difficult to expand the range of dimming with high accuracy unless measures such as increasing the frequency of the control signal are taken with PWM control alone, the dimming level range is shared by different control methods to improve this. ing.

  The switching light control level can be set for each light source 2. In this example, the switching light control level is set to 30% of the maximum light control level.

  In the above description, the dimming control unit 4 takes the output to the drive circuit 52 as a control signal. However, numerical data of the amplitude value and the duty ratio may be output instead of the control signal. In that case, the drive circuit 52 has a function of generating a PWM control signal B having these values from the input amplitude value and numerical value of the duty ratio.

  The light source 2 and the DC power supply unit 51 may be connected to the drain instead of the source of the FET, or may be connected separately to the source and drain.

  Note that the configurations of the dimming control unit 4 and the drive unit 5 need not be limited to the example shown in FIG. When the dimming signal from the dimming level setting unit 3 is received and the dimming level specified by the dimming signal is equal to or higher than the switching dimming level, the drive current is set by analog control. Any configuration may be used as long as the configuration is supplied.

  In addition, the organic EL element is characterized in that light emission efficiency by analog control is higher than that by PWM control. The high luminous efficiency means that an equivalent light output can be obtained with a small amount of power, which meets the demand for power saving. On the other hand, as already described, dimming by PWM control is necessary for a low dimming level from the viewpoint of reducing variation in light output between the light sources 2 and reducing variation in lighting and extinguishing timing. Therefore, when the light source 2 is composed of an organic EL element, by appropriately setting the switching light control level, in addition to the effects described so far, the effect of contributing to power saving as the entire lighting device 1 is achieved. You can expect. Setting the switching dimming level appropriately means that the setting is made in a balance between power saving and a request for expanding the range in which dimming can be performed with high accuracy.

(Embodiment 2)
In the second embodiment, in addition to the contents of the first embodiment, the switching dimming level is the same and appropriate between the plurality of light sources 2 of the same type (the light emission principle and the nominal light output are the same) among the plurality of light sources 2. It is to set to. The structural example of the illuminating device which concerns on Embodiment 2 is the same as that of FIG.

  In the dimming control by analog control, the difference in light output between the light sources 2 with respect to the set dimming level is large particularly at a low dimming level. Therefore, even if the light source 2 is the same type, when switching from PWM control to analog control at a low dimming level, a difference in light output occurs between the light sources 2 due to variations in characteristics of the drive unit 5 and the like. . However, when the light output is large, the eye discriminating power with respect to the difference in the light output is reduced. Therefore, as the dimming level is increased, the difference in the light output due to the variation in the characteristics of the drive unit 5 is the brightness by visual observation. It is difficult to recognize the difference. Therefore, the switching dimming level shown in FIG. 2 is unified between the same types of light sources 2 and set to a somewhat high dimming level, and the dimming level setting unit 3 installed in common for the plurality of light sources 2 is used. By dimming, it is possible to eliminate the difference in visual brightness between the light sources 2 when the dimming control method is switched. In the example of FIG. 2, the switching dimming level is set to 30% of the maximum dimming level. That is, the light control level corresponds to the case where the amplitude value of the drive current supplied to the light source 2 is approximately 30% of the amplitude value (peak current value) of the rated current. If the switching dimming level is set to such a dimming level, the difference in visual brightness between the light sources 2 associated with the switching of the control method is eliminated. This switching level varies depending on the rating of the light source 2.

  FIG. 3 shows a configuration example of a lighting device 1 according to another modification of the second embodiment. In this example, a plurality of light sources 2 are divided into a plurality of groups, and each group includes one or a plurality of the same type of light sources 2, a drive unit 5 associated with the light sources 2, and a dimming control unit common to the groups. One set of four. It does not matter whether the types of the light sources 2 are the same between the groups. Although details of the drive unit 5 are omitted, the details are the same as those of the first embodiment including other configurations.

  In such a case, the variation in the timing of turning on and off between all the light sources 2 is reduced, and by adopting an appropriately set switching dimming level, the light source at the time of switching the control method within each group Variation in brightness between the two is reduced. Note that the variation in lighting and extinguishing timing among all the light sources 2 depends on the dimming level setting equal to or lower than the switching dimming level, and is not affected even if the switching dimming level differs among the groups.

  A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.

(Supplementary note 1) a plurality of light sources composed of light emitting elements that emit light by applying current;
A dimming level setting unit that sets the same dimming level at a common timing for the plurality of light sources;
When the set dimming level is less than a predetermined level (switching dimming level) with respect to the current flowing through the light source, the amplitude value of the current is fixed to a predetermined value, and the duty of the current is set. The ratio is determined to be a value changed according to the set dimming level, and when the set dimming level is equal to or higher than the switching dimming level, the duty ratio is fixed to 100%, and the amplitude value A dimming control unit that determines a value changed according to the set dimming level;
A drive unit configured to supply current supplied to each light source as a drive current having an amplitude value proportional to the determined amplitude value and the determined duty ratio;
A lighting device comprising:

(Additional remark 2) The said dimming control part is provided for every said each light source, The illuminating device of Additional remark 1 characterized by the above-mentioned.

(Appendix 3) The plurality of light sources are divided into a plurality of light source groups, the light sources belonging to each light source group are of the same type, and one dimming control unit is provided for each light source group. The lighting device according to Supplementary Note 1.

(Supplementary note 4) The lighting device according to any one of supplementary notes 1 to 3, wherein the switching dimming level of the dimming control unit is set to be the same between the light sources of the same type.

(Supplementary note 5) The lighting device according to any one of supplementary notes 1 to 4, wherein the plurality of light sources includes a light source composed of an organic EL element.

  It can be used for a lighting device in which a plurality of light sources are turned on at the same time in a large facility.

DESCRIPTION OF SYMBOLS 1 Illuminating device 2 Light source 3 Dimming level setting part 4 Dimming control part 5 Drive part 41 Analog control part 42 PWM control part 51 DC power supply part 52 Drive circuit 53 Switching circuit

Claims (3)

A plurality of light sources composed of light emitting elements that emit light by energizing current;
A dimming level setting unit that sets the same dimming level at a common timing for the plurality of light sources;
When the set dimming level is less than a predetermined level (switching dimming level) with respect to the current flowing through the light source, the amplitude value of the current is fixed to a predetermined value, and the duty of the current is set. The ratio is determined to be a value changed according to the set dimming level, and when the set dimming level is equal to or higher than the switching dimming level, the duty ratio is fixed to 100%, and the amplitude value A dimming control unit that determines a value changed according to the set dimming level;
A drive unit configured to supply current supplied to each light source as a drive current having an amplitude value proportional to the determined amplitude value and the determined duty ratio;
Equipped with a,
The plurality of light sources are divided into a plurality of light source groups, and the light sources belonging to each light source group are of the same type,
One dimming control unit is provided for each light source group,
Lighting device comprising a call. The lighting device according to claim 1, wherein the switching dimming level of the dimming control unit is set to be the same between the light sources of the same type. Wherein the plurality of light sources illuminating device according to claim 1 or 2, characterized in that comprising a light source configured of an organic EL element.

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