JP5816074B2 - Lighting device - Google Patents

Description

  The present invention relates to a lighting device capable of stably adjusting brightness and correlated color temperature while suppressing the influence of light emission characteristics (variation) of light emitting diodes (LEDs).

  It has been proposed to apply LEDs to lighting devices. As dimming technology, several proposals have been made for current control in a low luminance region where the current supplied to the LED is small (see, for example, Patent Document 1 to Patent Document 3).

  These patent documents disclose dimming for monochromatic LEDs, but do not disclose dimming and toning for LEDs having different correlated color temperatures.

JP 2008-60222 A JP 2009-54425 A JP 2006-135297 A

  As described above, the dimming technique for the LED having a single correlated color temperature is disclosed in the conventional patent document, but the first LED having the first correlated color temperature and the second LED having the second correlated color temperature are disclosed. There is no disclosure of a technique for performing dimming and toning for two LEDs.

  In addition, as the use of LEDs for lighting devices spreads, new proposals regarding deep light control that effectively perform light control and color adjustment in a wide range are required.

  The present invention has been made in view of such a situation. When dimming control is performed based on a designated brightness, or when toning control is performed based on a designated correlated color temperature, an LED is used. When the current value supplied to the (first LED and the second LED) is supplied with a current smaller than the specific current value with the specific current value specified in advance as a boundary, pulse width modulation is applied to the direct current having the specific current value. When driving currents (first driving current, second driving current) and supplying a current greater than or equal to a specific current value, a direct current is supplied so that the light emission characteristics of the LED can be achieved even when driving in a current range smaller than the specific current value. It is possible to stably adjust the brightness and correlated color temperature by suppressing the influence of (variation), and to perform dimming control and toning control over a wide range with high accuracy and effectiveness. And to provide an illuminating device capable.

The illumination device according to the present invention includes a first LED that emits light at a first correlated color temperature, a first drive circuit that supplies a first drive current to the first LED, a second LED that emits light at a second correlated color temperature, A lighting device comprising: a second drive circuit that supplies a second drive current to a second LED; and a drive control unit that controls the first drive circuit and the second drive circuit, wherein the current value of the first drive current The current value of the second drive current is defined in advance in correspondence with the brightness and the correlated color temperature of each of the first LED and the second LED that are to be controlled, and the brightness and the correlated color temperature are designated. If it is, it prespecified of a lower limit value of the current value of the first driving current corresponding to the specified the brightness and the correlated color temperature, a stable direct current based on said first 1LED emission characteristics When in less than a certain current value, the first driving circuit, the first corresponding to the specific current value to the brightness and the correlated color temperature designated by performing a pulse width modulation DC current to the H level When a current value of the first drive current corresponding to the designated brightness and correlated color temperature is greater than the specific current value, a drive current is generated and supplied to the first LED. Generates the first drive current of a direct current corresponding to the specified brightness and the correlated color temperature and supplies the first drive current to the first LED, and the first brightness corresponds to the specified brightness and the correlated color temperature. the current value of the second driving current, is smaller than the pre-specified specified current value as the lower limit of the stable DC current based on the emission characteristics of the first 2LED, the second driving circuit, the specific electric current value And generating the second driving current corresponding to the brightness and the correlated color temperature designated by performing a pulse width modulation DC current level supplied to the first 2LED, designated the brightness and the When the current value of the second drive current corresponding to the correlated color temperature is greater than the specific current value, the second drive circuit causes the second current of the direct current corresponding to the designated brightness and the correlated color temperature to be determined. It is configured to generate two drive currents and supply them to the second LED.

  Therefore, the lighting device according to the present invention performs LED dimming control based on the designated brightness or when toning control is performed based on the designated correlated color temperature. When a current smaller than the specific current value is supplied with a specific current value specified in advance as a boundary, a direct current having the specific current value is subjected to pulse width modulation to drive current (first drive) Current, the second drive current), and when a current greater than a specific current value is supplied, a direct current is supplied. Therefore, even when driving in a current range smaller than the specific current value, the LED emission characteristics (variation) have an effect. Accordingly, it is possible to stably adjust the brightness and the correlated color temperature, and the light control and the color control in a wide range can be performed with high accuracy and effectively.

  In the illumination device according to the present invention, the specific current value is specified in advance based on the light emission characteristics of the first LED and the light emission characteristics of the second LED.

  Therefore, since the specific current value is specified based on the light emission characteristics of the first LED and the second LED, the lighting device according to the present invention is a current obtained by applying PWM to the direct current having the specific current value as the H level. Since the first LED and the second LED are driven (controlled), even when the light emission characteristics of the first LED and the second LED vary in a low current region (a current region smaller than a specific current value), stable and accurate brightness control ( Dimming control) and correlated color temperature control (toning control) can be realized to perform a wide range of stable dimming and toning.

  In the illumination device according to the present invention, the first LED and the second LED are connected in parallel between a DC power supply and a reference potential line, and one end of the first drive circuit is connected to the reference potential line. A first current detecting element, a first switching element connected between the other end of the first current detecting element and the first LED, a first non-inverting input terminal, and a first inverting input terminal. A first operational amplifier that controls on / off of the first switching element; and a first reference voltage source that inputs a first reference voltage to the first non-inverting input terminal; and the first current detection element and the first A potential at a connection point with the switching element is input to the first inverting input terminal of the first operational amplifier, and the second drive circuit includes a second current detection element having one end connected to the reference potential line. , The other end of the second current detection element A second switching element connected between the second LED, a second operational amplifier having a second non-inverting input terminal and a second inverting input terminal and controlling on / off of the second switching element; And a second reference voltage source for inputting a second reference voltage to the non-inverting input terminal, and the potential at the connection point between the second current detection element and the second switching element is the second operational amplifier. It is inputted to the inverting input terminal.

  Therefore, the lighting device according to the present invention supplies a constant current (first drive current) according to the first reference voltage from the first drive circuit to the first LED, and a constant current (second drive) according to the second reference voltage. Current) is supplied from the second drive circuit to the second LED, so that the first drive circuit and the second drive circuit function as constant current circuits, and therefore the dimming control and the toning control for the first LED and the second LED are highly accurate. Can be realized.

  In the illumination device according to the present invention, the drive control unit controls the first reference voltage of the first reference voltage source in correspondence with the first drive current supplied to the first LED, and the second LED. The second reference voltage of the second reference voltage source is controlled in accordance with the second drive current supplied to the second reference current source.

  Therefore, in the lighting device according to the present invention, the drive control unit adjusts the first reference voltage corresponding to the first drive current, and the drive control unit adjusts the second reference voltage corresponding to the second drive current. Therefore, the first drive current and the second drive current corresponding to the dimming control and the toning control are easily generated, and the first drive current and the second drive current corresponding to the specific current value are easily generated. Can do.

  In the illumination device according to the present invention, a third switching element connected between the reference potential line and the first non-inverting input terminal of the first operational amplifier, the reference potential line, and the second computation. And a fourth switching element connected between the second non-inverting input terminal of the amplifier.

  Therefore, the lighting device according to the present invention turns on and off the third switching element to turn on and off the input to the first non-inverting input terminal of the first operational amplifier, and thus easily and reliably perform pulse width modulation for a specific current value. The first driving current subjected to the pulse width modulation and supplied to the first LED 11 and the fourth switching element is turned on / off to turn on / off the input to the non-inverting input terminal of the second operational amplifier. The second drive current subjected to the pulse width modulation is supplied to the second LED 12 by easily and reliably performing the pulse width modulation on the current value.

  In the illumination device according to the present invention, the first correlated color temperature is a warm color system, and the second correlated color temperature is a cold color system.

  Therefore, the lighting device according to the present invention can perform toning in a wide range from warm colors to cold colors, and can perform dimming while maintaining the same toning, so that a wide range of toning can be performed. Light control and toning control can be performed without a sense of incongruity.

  In the illumination device according to the present invention, the first LED is a first LED group including a plurality of LEDs having the same specification, and the second LED is a second LED group including a plurality of LEDs having the same specification. And

  Therefore, since the illuminating device according to the present invention is an illuminating device that can obtain a large light output, it can be replaced with a conventional luminaire.

  The lighting device according to the present invention controls the LEDs (first LED and second LED) when performing dimming control based on the designated brightness or performing toning control based on the designated correlated color temperature. As for the current value to be supplied, when supplying a current smaller than the specific current value with a specific current value specified in advance as a boundary, a direct current having the specific current value is subjected to pulse width modulation to drive current (first drive current, The second driving current) is used, and a direct current is supplied when a current exceeding a specific current value is supplied.

  Therefore, the lighting device according to the present invention can stably adjust the brightness and the correlated color temperature while suppressing the influence of the light emission characteristics (variation) of the LED even when driving in a current range smaller than the specific current value. Thus, there is an effect that dimming control and toning control in a wide range can be performed with high accuracy and effectiveness.

It is a block diagram which shows the functional block of the illuminating device which concerns on Embodiment 1 of this invention. It is a flowchart which shows the basic operation | movement flow in the illuminating device shown in FIG. FIG. 2 is a circuit diagram specifically illustrating a mutual relationship among a first drive circuit, a second drive circuit, a first LED, and a second LED in the illumination device illustrated in FIG. 1. It is a graph which shows the correlation of the light control stage number in the illuminating device 1 which concerns on Embodiment 2 of this invention, the number of toning stages, the 1st drive current, the 2nd drive current, and the toning correlation color temperature. The dimming rate (the number of dimming steps) versus the toning-correlated color temperature when the dimming control and the toning control are performed by the first driving current and the second driving current shown in FIG. It is a graph which shows the state of. The dimming rate (the number of dimming steps) versus the toning correlation color temperature when the dimming control and the toning control are performed by the first driving current and the second driving current shown in FIG. It is a graph which shows the state of. The dimming rate (the number of dimming steps) versus the toning-correlated color temperature when the dimming control and the toning control are performed by the first driving current and the second driving current shown in FIG. It is a graph which shows the state of. The dimming rate (the number of dimming steps) versus the toning correlation color temperature at the number of toning steps (6 steps) when the dimming control and the toning control are performed by the first drive current and the second drive current shown in FIG. It is a graph which shows the state of. The graph which shows the state of the light control stage number versus the color control correlation color temperature in the color control stage number (9 steps) when performing the light control and the color control by the first drive current and the second drive current shown in FIG. It is. The graph which shows the state of the light control stage number versus the color control correlation color temperature in the color control stage number (10 steps) when performing the light control and the color control by the first drive current and the second drive current shown in FIG. It is. As a comparative example, the number of dimming steps, the number of toning steps, the first driving current, the second driving current, and the toning correlated color when the minimum value of dimming control is set for the lighting apparatus according to Embodiment 1 of the present invention It is a graph which shows the correlation of temperature. The dimming rate (the number of dimming steps) versus the toning correlation color temperature at the number of toning steps (one step) when the dimming control and the toning control are performed by the first driving current and the second driving current shown in FIG. It is a graph which shows the state of. The dimming rate (the number of dimming steps) versus the toning correlation color temperature when the dimming control and the toning control are performed by the first driving current and the second driving current shown in FIG. It is a graph which shows the state of. The dimming rate (the number of dimming steps) versus the toning correlation color temperature at the number of toning steps (6 steps) when the dimming control and the toning control are performed by the first driving current and the second driving current shown in FIG. It is a graph which shows the state of. The dimming rate (the number of dimming steps) versus the toning correlation color temperature when the dimming control and the toning control are performed by the first driving current and the second driving current shown in FIG. It is a graph which shows the state of.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1>
With reference to FIG. 1 thru | or FIG. 3, the illuminating device 1 which concerns on this Embodiment is demonstrated. The lighting device 1 according to the present embodiment changes the magnitude relationship between the light emission states (drive currents) of the first LED 11 that emits a warm color and the second LED 12 that emits a cool color. Toning (adjustment of correlated color temperature) and dimming (adjustment of brightness) with the correlated color temperature fixed are possible. Details will be described below.

  FIG. 1 is a block diagram showing functional blocks of lighting apparatus 1 according to Embodiment 1 of the present invention.

  The lighting device 1 according to the present embodiment includes a first LED 11 that emits light at a first correlated color temperature CT1 (for example, a correlated color temperature 2700K (Kelvin) in a warm color system), and a first drive current Idw that supplies the first LED 11 with a first drive current Idw. A first drive circuit 13, a second LED 12 that emits light at a second correlated color temperature CT2 (for example, a correlated color temperature of 6500 K (Kelvin) in a cold color system), and a second drive circuit 14 that supplies a second drive current Idc to the second LED 12 And a drive control unit 23 for controlling the first drive circuit 13 and the second drive circuit 14.

  The first LED 11 includes a plurality of LEDs having the same specification as the first LED 11 connected in series or in parallel as required (see FIG. 3), and the second LED 12 includes a plurality of LEDs having the same specification as the second LED 12. LEDs are connected in series or in parallel as many as required (see FIG. 3). That is, the first LED 11 is preferably a first LED group including a plurality of LEDs having the same specification, and the second LED 12 is preferably a second LED group including a plurality of LEDs having the same specification. Below, even if it is an LED group containing several LED, it describes only as 1st LED11 and 2nd LED12.

  Therefore, since the 1st LED11 and the 2nd LED12 are made into LED group, respectively since the illuminating device 1 can obtain a big light output, it becomes possible to replace the conventional illuminating device. Hereinafter, the first LED 11 and the second LED 12 may be simply LEDs.

  In the illuminating device 1, the current value of the first drive current Idw and the current value of the second drive current Idc are the brightness to be controlled (the number of light control stages LCm (for example, 10 stages of m = 1 to 10)), see FIG. ) And the correlated color temperature (the toning stage number DCn (for example, 10 stages of n = 1 to 10). See FIG. 4), and the brightness and the correlated color determined by the light emission of the first LED 11 and the second LED 12 When the temperature is specified and the current value of the first drive current Idw corresponding to the specified brightness and correlated color temperature is smaller than the specific current value Iu specified in advance (see FIGS. 4 and 6), The first drive circuit 13 applies a pulse width modulation (hereinafter, may be referred to as PWM) to a direct current equal to the specific current value Iu and corresponds to the designated brightness and correlated color temperature. Raw Idw It is constructed as supplied to the 1LED11 with.

  In the lighting device 1, when the current value of the first drive current Idw corresponding to the designated brightness and correlated color temperature is greater than the specific current value Iu, the first drive circuit 13 A first drive current Idw of a direct current corresponding to the correlated color temperature is generated and supplied to the first LED 11.

  Further, in the lighting device 1, when the current value of the second drive current Idc corresponding to the designated brightness and correlated color temperature is smaller than the specific current value Iu specified in advance, the second drive circuit 14 A DC current equal to Iu is subjected to pulse width modulation to generate a second drive current Idc corresponding to the specified brightness and correlated color temperature and supply it to the second LED 12 to correspond to the specified brightness and correlated color temperature When the current value of the second drive current Idc is greater than the specific current value Iu, the second drive circuit 14 generates a second drive current Idc of DC current corresponding to the specified brightness and correlated color temperature. It is set as the structure supplied to 2nd LED12.

  Therefore, the lighting device 1 according to the present embodiment performs the dimming control based on the designated brightness (the dimming stage number LCm) or based on the designated correlated color temperature (the toning stage number DCn). When the color control is performed, the current values (first drive current Idw, second drive current Idc) supplied to the LEDs (first LED 11 and second LED 12) are specified current values with the specified specific current value Iu as a boundary. When supplying a current smaller than Iu, a direct current having a specific current value Iu is subjected to pulse width modulation to obtain a drive current (first drive current Idw, second drive current Idc). When supplying, a direct current is supplied. Therefore, even when driving in a current range smaller than the specific current value Iu, the influence of the light emission characteristics (variation) of the LED is suppressed and the brightness and brightness are suppressed. It is possible to adjust the correlated color temperature stably, it is possible to perform the dimming control and toning control over a wide range and effectively with high accuracy. That is, deep light control is possible.

  The first correlated color temperature CT1 is preferably a warm color system (first correlated color temperature CT1 = 2600K), for example, and the second correlated color temperature CT2 is preferably a cold color system (second correlated color temperature CT2 = 6500K), for example. With this configuration, the lighting device 1 can perform toning in a wide range from warm colors to cold colors, and perform dimming while maintaining the same toning (same correlated color temperature). Therefore, a wide range of light control and color control can be performed without a sense of incongruity.

  The specific current value Iu is specified (selected) in advance for variations in the light emission characteristics (element characteristics: element constant) of the individual LEDs constituting the first LED 11 and the second LED 12. For example, when the same DC current (forward current) is passed, in the low current region range where the DC current is small (the range smaller than the specific current value Iu), the variation in the light emission characteristics is directly manifested as the light emission state. Thus, it has been found that the variation in the light emission state of the LED can be visually recognized, resulting in an unstable light emission state. That is, for example, even when the same forward current is passed, it is difficult to realize a stable lighting device having a greatly different light emission state.

  As the specific current value Iu, for example, a current of about 2% to 5% is specified with respect to the maximum rated current (the current when the dimming rate (or POWER) is 100% in FIG. 4, for example). Can do. When this current value is reached, variations in the light emission state (element characteristics) of the LEDs appear as variations in the light emission state as they are.

  In the present embodiment, the specific current value Iu is specified as being within a range of 2% to 5%, for example, and a current smaller than the specific current value Iu is supplied as the specified light control stage number LCm and the current value of the second drive current Idc. When necessary, PWM is applied to the specific current value Iu to realize a current value smaller than the specific current value Iu, so that the drive current (first LED 11, second LED 12) supplied to the LEDs (first LED 11, second LED 12) The drive current Idw and the second drive current Idc) can secure a specific current value Iu at a DC value level.

  That is, no matter how small the first drive current Idw and the second drive current Idc are formed by applying PWM to the specific current value Iu, and the direct current level (high level (H level)) of the flowing current is set. Since the specific current value Iu is secured as the specific current value Iu and is supplied as the stable lower limit value of the direct current, a stable lighting state that does not cause a sense of incongruity even when driven in a low current region can be realized. . The operation and effect of the specific current value Iu will be further described in Embodiment 2 (FIG. 4 and subsequent figures).

  As described above, currents smaller than the specific current value Iu (first drive current Idw, second drive current Idc) are formed by pulse width modulation of a direct current equal to the specific current value Iu. Therefore, when a current smaller than the specific current value Iu is supplied to the LED, the specific current value Iu is secured as it is when the LED is in an on state (a period corresponding to a high level (H) in PWM). The influence of LED variation can be suppressed, and when the LED is in an off state (a period corresponding to a low level (L) in PWM), the current value is zero, so there is no influence due to LED variation. Therefore, even when driving with a current smaller than the specific current value Iu, a current substantially smaller than the specific current value Iu does not flow, so that a stable lighting state can be ensured.

  As described above, in the present embodiment, the specific current value Iu is specified in advance based on the light emission characteristics of the first LED 11 and the light emission characteristics of the second LED 12. That is, since the specific current value Iu is specified on the basis of the light emission characteristics of the first LED 11 and the second LED 12, the lighting device 1 uses the current obtained by applying PWM to the direct current having the specific current value Iu as the H level. Since the first LED 11 and the second LED 12 are driven (controlled), the light emission characteristics of the first LED 11 (the plurality of first LEDs 11) and the second LED 12 (the plurality of second LEDs 12) vary in a low current region (current region smaller than the specific current value Iu). Even in this case, stable high-precision brightness control (light control) and correlated color temperature control (color control) can be realized, and a wide range of stable light control and color control can be performed.

  The brightness and the correlated color temperature are designated by, for example, input to the designation signal input unit 21 from the remote controller 30 as the designation signal transmission unit. The designation signal is a signal that designates the dimming stage number LCm (m = 1 to 10) for brightness, and the signal that designates the toning stage number DCn (n = 1 to 10) for the correlated color temperature. is there. In the present embodiment, when m = 1 (dimming step number LC1), for example, the dimming state is 100%, and when m = 10 (dimming step number LC10), the dimming state is, for example, 10% (see FIG. 4). Further, when n = 1 (toning step number DC1), the combined correlated color temperature CCT is, for example, the first correlated color temperature CT1 (2700K), and when n = 10 (toning step number DC10), the combined correlation. The color temperature CCT is, for example, the second correlated color temperature CT2 (6500K) (see FIG. 4).

  In addition, although the input of the designation signal via the remote controller 30 has been exemplified, it may be input directly to the designation signal input unit 21.

  The designation signal input from the remote controller 30 to the designation signal input unit 21 is determined by the designation signal determination unit 22 of the transfer destination. The number of dimming stages LCm (m value) and the number of toning stages DCn (n Value) is determined (extracted). The drive control unit 23 extracts the first drive current Idw and the second drive current Idc corresponding to the light control stage number LCm and the toning stage number DCn determined by the designation signal determination unit 22 from the data storage unit 24.

  The data storage unit 24 lists characteristics of the first drive current Idw and the second drive current Idc that are defined in advance in correspondence with the brightness (light control stage number LCm) and the correlated color temperature (color control stage number DCn) as the control target. It is stored as a table (see FIG. 4). That is, the data storage unit 24 uses a characteristic list of the relationship between the designation signal (the dimming stage number LCm, the toning stage number DCn) and the current data (the current value of the first drive current Idw, the current value of the second drive current Idc). I have it.

  The data storage unit 24 also stores the value of the specific current value Iu. The data storage unit 24 is formed by a flash memory, for example. Further, the current value may be stored in place of an appropriate substitute signal.

  As described above, in the illuminating device 1, the current value of the first drive current Idw and the second drive current Idc that are defined in advance corresponding to the brightness (the light control stage number LCm) and the correlated color temperature (the color control stage number DCn). Are stored in the data storage unit 24 as a characteristic list.

  Therefore, the lighting device 1 stores the values of the first drive current Idw and the second drive current Idc corresponding to the brightness and the correlated color temperature as a characteristic list (characteristic data) in the data storage unit 24. Light control and color control can be performed easily and with high accuracy.

  For example, the control unit 20 configured by a CPU (Central Processing Unit) cooperates with the remote controller 30. Further, the control unit 20 controls operations of the designation signal input unit 21, the designation signal determination unit 22, the drive control unit 23, and the data storage unit 24 via the bus 20b. The operation required for the designation signal input unit 21, the designation signal determination unit 22, the drive control unit 23, and the data storage unit 24 is written in advance as a program, and the control unit 20 uses the designation signal input unit based on the written program. 21, controls the designation signal determination unit 22, the drive control unit 23, and the data storage unit 24.

  FIG. 2 is a flowchart showing a basic operation flow in the lighting device 1 shown in FIG.

  The lighting device 1 determines the content of the designation signal when the designation signal (the light adjustment stage number LCm, the toning stage number DCn) is input, and corresponds to the first drive current Idw and the second drive current Idc corresponding to the designation signal. Current value data to be read is read (extracted) from the data storage unit 24. Next, it is determined whether or not the read current values of the first drive current Idw and the second drive current Idc are larger than the specific current value Iu. When the first drive current Idw or the second drive current Idc is smaller than the specific current value Iu, the drive by the direct current for the first LED 11 and the second LED 12 is changed to the drive by PWM to drive the first LED 11 or the second LED 12 To do. Specifically, the above operation is executed by the following steps S2 to S12.

Step S2:
The designation signal input unit 21 determines the presence / absence of designation based on the input status of the designation signal from the remote controller 30 (the dimming stage number LCm for brightness and the toning stage number DCn for correlated color temperature).

  If specified (step S2: YES), the process proceeds to step S4. If there is no designation (step S2: NO), the process returns to the original.

Step S4:
The designation signal determination unit 22 determines designation contents (designated step number, that is, light control step number LCm, toning step number DCn). That is, the value of m at the light control stage number LCm and the value of n at the toning stage number DCn are determined (extracted). The determination result (value of m, value of n) for the light control stage number LCm and the toning stage number DCn is transmitted to the drive control unit 23.

Step S6:
Based on the determination result in step S4, the drive control unit 23 determines the designation signal (m at the dimming stage number LCm, n at the toning stage number DCn from the characteristic list (data storage unit 24) regarding the designated signal versus current data. ) Corresponding to the first drive current Idw and the second drive current Idc are extracted (see FIG. 4).

  That is, the drive control unit 23 reads from the data storage unit 24 the current value of the first drive current Idw and the current value of the second drive current Idc corresponding to the light control stage number LCm and the toning stage number DCn.

Step S8:
The drive control unit 23 determines whether or not the extracted first drive current Idw or second drive current Idc is smaller than the specific current value Iu.

  When the current value of the first drive current Idw or the second drive current Idc is smaller than the specific current value Iu (step S8: YES), the process proceeds to step S10. On the other hand, when it is larger than the specific current value Iu (step S8: NO), the process proceeds to step S12.

Step S10:
The drive control unit 23 applies pulse width modulation to a direct current equal to the specific current value Iu for the first drive current Idw or the second drive current Idc that is smaller than the specific current value Iu, and performs the corresponding first drive current Idw or second drive. A current Idc is generated. The generation of the first drive current Idw or the second drive current Idc is executed by the first drive circuit 13 or the second drive circuit 14 based on a signal (instruction) from the drive control unit 23.

  That is, by applying PWM to the specific current value Iu, the DC value of the current supplied to the first LED 11 or the second LED 12 (current value when the duty ratio is 100%. That is, at the H level (high level) Since the current value) holds the specific current value Iu, the first LED 11 or the second LED 12 can substantially ensure normal operation, and thus maintains a stable lighting state. Further, the first driving current Idw or the second driving current Idc defined in advance is controlled to be equal to a value smaller than the specific current value Iu by the duty ratio of the PWM with respect to the specific current value Iu.

  For example, when the specific current value Iu is specified to be 5 mA, when 4 mA is defined as the first drive current Idw, the PWM is (5 mA × 80%) / 100% = 4 mA. Is 5 mA (current value at a duty ratio of 100%), and the duty ratio is 80%. A specific example will be further described in Embodiment 2 (FIG. 4).

  The first drive current Idw or the second drive current Idc subjected to PMW is supplied from the first drive circuit 13 or the second drive circuit 14 to the corresponding first LED 11 or second LED 12.

Step S12:
The drive control unit 23 generates a direct current corresponding to the first drive current Idw or the second drive current Idc. The generation of the first drive current Idw or the second drive current Idc as a direct current is executed by the first drive circuit 13 or the second drive circuit 14 based on a signal (instruction) from the drive control unit 23. The circuit operations of the first drive circuit 13 and the second drive circuit 14 will be further described with reference to FIG.

  That is, the first drive current Idw or the second drive current Idc that is a direct current is supplied from the first drive circuit 13 or the second drive circuit 14 to the corresponding first LED 11 or second LED 12.

  The operations of the drive control unit 23, the first drive circuit 13, and the second drive circuit 14 will be described with reference to FIG.

  FIG. 3 is a circuit diagram specifically showing the mutual relationship between the first drive circuit 13, the second drive circuit 14, the first LED 11, and the second LED 12 in the lighting device 1 shown in FIG.

  In addition, since the 1st drive circuit 13 and the 2nd drive circuit 14 are controlled by the drive control part 23, the drive control part 23 is further demonstrated collectively.

  The first LED 11 and the second LED 12 are connected in parallel between the DC power supply PS1 and the reference potential line BS, and the first drive circuit 13 is connected in series to the first LED 11 so that the first drive current Idw flows, and the second LED 12 The second drive circuit 14 is connected in series so that the second drive current Idc flows.

  As for 1st LED11 and 2nd LED12, several LED of the same specification is connected in series, respectively. Further, they may be further connected in parallel. For example, the first LED 11 and the second LED 12 may be in a connected state of 20 series × 4 parallel LEDs (a total of 80 LEDs are mounted). That is, as described above, the first LED 11 is a first LED group including a plurality of LEDs having the same specification, and the second LED 12 is a second LED group including a plurality of LEDs having the same specification.

  The first driving circuit 13 includes a first operational amplifier OP1 having a first reference voltage source VS1 that generates a first reference voltage Vref1, a first non-inverting input terminal Tin1 to which the first reference voltage Vref1 is input, and a first operational amplifier OP1. A first switching element Q11 that is on / off controlled by an output of the operational amplifier OP1 and a first current detection element R1 connected between the first switching element Q11 and the reference potential line BS are provided, and the first current detection element R1 And a potential at a connection point between the first switching element Q11 is input to the first inverting input terminal Tin2 of the first operational amplifier OP1. With this configuration, the first drive circuit 13 can flow a constant current (first drive current Idw) corresponding to the first reference voltage Vref1 to the first switching element Q11, and drives the first LED 11 with a constant current.

  The second driving circuit 14 includes a second reference voltage source VS2 that generates the second reference voltage Vref2, a second operational amplifier OP2 having a second non-inverting input terminal Tin3 to which the second reference voltage Vref2 is input, A second switching element Q21 that is on / off controlled by the output of the operational amplifier OP2; and a second current detection element R2 connected between the second switching element Q21 and the reference potential line BS. Is connected to the second inverting input terminal Tin4 of the second operational amplifier OP2. With this configuration, the second drive circuit 14 can flow a constant current (second drive current Idc) corresponding to the second reference voltage Vref2 to the second switching element Q21, and drives the second LED 12 with a constant current.

  The first switching element Q11 and the second switching element Q21 are configured by MOSFETs, and the first current detection element R1 and the second current detection element R2 are configured by resistors.

  As described above, in the lighting device 1, the first LED 11 and the second LED 12 are connected in parallel between the DC power source PS1 and the reference potential line BS.

  In the lighting device 1, the first drive circuit 13 is connected between the first current detection element R <b> 1 having one end connected to the reference potential line BS, and the other end of the first current detection element R <b> 1 and the first LED 11. A first operational amplifier OP1 having a first switching element Q11, a first non-inverting input terminal Tin1 and a first inverting input terminal Tin2, and controlling on / off of the first switching element Q11; and a first non-inverting input terminal Tin1. And a first reference voltage source VS1 for inputting the first reference voltage Vref1, and the potential at the connection point between the first current detection element R1 and the first switching element Q11 is the first inverting input terminal Tin2 of the first operational amplifier OP1. Has been entered.

  In the lighting device 1, the second drive circuit 14 is connected between the second current detection element R <b> 2 having one end connected to the reference potential line BS, the other end of the second current detection element R <b> 2, and the second LED 12. A second operational amplifier OP2 having a second switching element Q21, a second non-inverting input terminal Tin3 and a second inverting input terminal Tin4 and controlling on / off of the second switching element Q21, and a second non-inverting input terminal Tin3. And a second reference voltage source VS2 for inputting the second reference voltage Vref2, and the potential at the connection point between the second current detection element R2 and the second switching element Q21 is the second inverting input terminal Tin4 of the second operational amplifier OP2. Has been entered.

  Accordingly, the lighting device 1 supplies a constant current (first drive current Idw) according to the first reference voltage Vref1 from the first drive circuit 13 to the first LED 11, and a constant current (second second) according to the second reference voltage Vref2. Since the drive current Idc) is supplied from the second drive circuit 14 to the second LED 12, the first drive circuit 13 and the second drive circuit 14 function as constant current circuits. Therefore, dimming control and dimming for the first LED 11 and the second LED 12 are performed. Color control can be realized with high accuracy.

  The drive control unit 23 (see FIG. 1) controls the first reference voltage Vref1 of the first reference voltage source VS1 corresponding to the first drive current Idw supplied to the first LED 11, and supplies the second LED 12 to the second LED 12. The second reference voltage Vref2 of the second reference voltage source VS2 is controlled in correspondence with the drive current Idc.

  That is, in the lighting device 1, the drive control unit 23 adjusts the first reference voltage Vref1 corresponding to the first drive current Idw, and the drive control unit 23 adjusts the second reference voltage Vref2 corresponding to the second drive current Idc. By adjusting, the first drive current Idw and the second drive current Idc corresponding to the dimming control (the dimming stage number LCm) and the toning control (the toning stage number DCn) are easily generated, and the specific current value Iu The first drive current Idw and the second drive current Idc corresponding to can be easily generated.

  Since the first reference voltage Vref1 is equal to the voltage drop at the first current detection element R1, the first reference voltage Vref1 = (resistance value r1 of the first current detection element R1) × first drive current Idw. Therefore, the first drive current Idw can be adjusted by adjusting the first reference voltage Vref1, and the second reference voltage Vref2, the resistance value r2 of the second current detection element R2, the second drive current Idc, and the like. This is the same, and the second drive current Idc can be adjusted by adjusting the second reference voltage Vref2.

  In order to perform PWM with respect to the first drive current Idw and the second drive current Idc, the first drive circuit 13 is connected to the third switching element Q12, and the second drive circuit 14 is connected to the fourth switching element Q22. Has been. That is, the third switching element Q12 is connected between the reference potential line BS and the first non-inverting input terminal Tin1 (first operational amplifier OP1), and the reference potential line BS and the second non-inverting input terminal Tin3 (second operation). The fourth switching element Q22 is connected to the amplifier OP2).

  Modulation pulses Pm1 and Pm2 whose duty ratios are adjusted by the drive control unit 23 are input to the input terminals of the third switching element Q12 and the fourth switching element Q22, and the first non-inverting input of the first operational amplifier OP1. The first reference voltage Vref1 that is input to the terminal Tin1 is turned on and off, and the second reference voltage Vref2 that is input to the second non-inverting input terminal Tin3 of the second operational amplifier OP2 is turned on and off. The third switching element Q12 and the fourth switching element Q22 are configured by bipolar transistors (BPT).

  By the operations of the third switching element Q12 and the fourth switching element Q22, the first drive current Idw is subjected to on / off control (PWM) according to the modulation pulse Pm1, and the second drive current Idc is determined according to the modulation pulse Pm2. On / off control (PWM) is performed. That is, the third switching element Q12 and the fourth switching element Q22 specify the direct current (H level current value) of the first drive current Idw and the second drive current Idc by the first reference voltage Vref1 and the second reference voltage Vref2. While maintaining the current value Iu, PWM is applied to the first drive current Idw and the second drive current Idc. The first drive circuit 13 and the second drive circuit 14 generate the designated first drive current Idw and second drive current Idc by adjusting the duty ratio of the modulation pulse Pm1 and the modulation pulse Pm2, and the first LED 11 , Supplied to the second LED 12.

  That is, the illumination device 1 (the first drive circuit 13 and the second drive circuit 14) includes the third switching element Q12 connected between the reference potential line BS and the first non-inverting input terminal Tin1 of the first operational amplifier OP1. And a fourth switching element Q22 connected between the reference potential line BS and the second non-inverting input terminal Tin3 of the second operational amplifier OP2.

  Therefore, since the third switching element Q12 is turned on / off to turn on / off the input to the first non-inverting input terminal Tin1 of the first operational amplifier OP1, pulse width modulation for the specific current value Iu can be easily and reliably performed. The first drive current Idw subjected to pulse width modulation is supplied to the first LED 11, and the fourth switching element Q22 is turned on / off to turn on / off the input to the second non-inverting input terminal Tin3 of the second operational amplifier OP2. Then, the pulse width modulation for the specific current value Iu is easily and reliably performed, and the second drive current Idc subjected to PWM is supplied to the second LED 12.

  That is, the first drive current Idw and the second drive current Idc, which are current values defined in advance by PWM and smaller than the specific current value Iu, are supplied to the first LED 11 and the second LED 12 while the H level maintains the specific current value Iu. can do.

  The first reference voltage Vref1 generated by the first reference voltage source VS1 is adjusted by the drive control unit 23 so that the first drive current Idw has a predetermined current value. Further, the second reference voltage Vref2 generated by the second reference voltage source VS2 is adjusted by the drive control unit 23 so that the second drive current Idc has a predetermined current value.

  When PWM is applied, the first reference voltage Vref1 and the second reference voltage Vref2 have a direct current portion (H level current value) of the current values of the first drive current Idw and the second drive current Idc obtained by PWM. The specific current value Iu is fixed.

  It should be noted that both the first LED 11 and the second LED 12 have directivity in the light emission state, and when actually acting as an illuminating device, optical diffusion for mixing light emitted on the front surfaces of the first LED 11 and the second LED 12 is performed. It is preferable to arrange the members.

  The lighting device 1 according to the present embodiment has been described above. In addition, the illuminating device 1 becomes invention which concerns on an LED lighting device in the state before 1st LED11 and 2nd LED12 are combined. Specifically, it is as follows.

  The LED lighting device according to the present invention includes a first drive circuit 13 that supplies a first drive current Idw to a first LED 11 that emits light at a first correlated color temperature CT1, and a second LED 12 that emits light at a second correlated color temperature CT2. A second drive circuit 14 that supplies the drive current Idc and a drive control unit 23 that controls the first drive circuit 13 and the second drive circuit 14 are provided.

  In the LED lighting device according to the present invention, the current value of the first drive current Idw and the current value of the second drive current Idc are defined in advance in correspondence with the brightness and the correlated color temperature to be controlled. If the current value of the first drive current Idw corresponding to the specified brightness and the correlated color temperature is smaller than the specific current value Iu specified in advance when the brightness and the correlated color temperature are specified, the first drive circuit 13 generates a first drive current Idw corresponding to the designated brightness and correlated color temperature by applying pulse width modulation to a direct current equal to the specific current value Iu, and supplies the first drive current Idw to the first LED 11 for the designated brightness. When the current value of the first drive current Idw corresponding to the correlated color temperature is greater than the specific current value Iu, the first drive circuit 13 generates a direct current corresponding to the designated brightness and correlated color temperature. When the first drive current Idw is generated and supplied to the first LED 11 and the current value of the second drive current Idc corresponding to the designated brightness and correlated color temperature is smaller than the specified specific current value Iu, the second The drive circuit 14 applies a pulse width modulation to a direct current equal to the specific current value Iu to generate a second drive current Idc corresponding to the designated brightness and correlated color temperature, and supplies the second drive current Idc to the second LED 12 for the designated LED. When the current value of the second drive current Idc corresponding to the brightness and the correlated color temperature is greater than the specific current value Iu, the second drive circuit 14 determines the first DC current corresponding to the designated brightness and the correlated color temperature. Two drive currents Idc are generated and supplied to the second LED 12.

<Embodiment 2>
With reference to FIGS. 4 to 5F and FIGS. 6 to 7D, dimming control of the lighting apparatus 1 according to the present embodiment, the dimming state by the toning control, the toning state, and the effects will be described. In addition, since the illuminating device 1 which concerns on this Embodiment is the illuminating device 1 which concerns on Embodiment 1, a code | symbol is used suitably and it mainly describes additional description. As described above, the correlated color temperature (first correlated color temperature) emitted by the first LED 11 is 2700 K (Kelvin), and the correlated color temperature (second correlated color temperature) emitted by the second LED 12 is 6500 K (Kelvin). ). Further, the specific current value Iu is exemplified for the case where both the first LED 11 and the second LED 12 are 2 mA, for example.

  In addition, in the first LED 11 (first LED group) and the second LED 12 (second LED group), the number of LEDs and the light emission efficiency were assumed to be equal, and the correlated color temperature CCT after mixing was calculated to be a weighted average. In order to simplify the explanation, the rated maximum values of the first drive current Idw and the second drive current Idc are set to 100 mA.

  FIG. 4 shows the correlation between the light control stage number LCm, the toning stage number DCn, the first driving current Idw, the second driving current Idc, and the toning correlation color temperature CCT in the illumination device 1 according to Embodiment 2 of the present invention. It is a chart.

  In the vertical direction of the chart, the dimming stage number LCm (10 stages of dimming stage number LC1 to dimming stage number LC10) is shown, and in the horizontal direction, the toning stage number DCn (toning stage number DC1 to 10 stages of toning stage DC10) is shown. The first drive current Idw and the second drive current Idc are defined in correspondence with the light control stage number LCm and the toning stage number DCn.

  In the present embodiment, the light control stage number LCm is linearly controlled from 100% to 0%, for example, in units of 10%. The toning stage number DCn is linearly controlled from the first correlated color temperature CT1 (2700K) with the toning stage number DC1 to the second correlated color temperature CT2 (6500K) with the toning stage number DC10. Note that the minimum value of the dimming control is 0%, and the control mode includes a mode in which either the first LED 11 or the second LED 12 is completely turned off.

  In the light control stage number LCm, the light control rate (%), that is, the brightness is controlled. The dimming rate of the light control stage number LC1 is 100% (maximum rated brightness), and is dimmed every 10%, and the dimming rate of the light control stage number LC10 is 10% (10% of the maximum rated brightness). ) The supplied power POWER (arbitrary unit) is matched with the dimming rate.

  In the toning stage number DCn, the toning correlated color temperature CCT (K), that is, the correlated color temperature is controlled. Since the toning correlation color temperature CCT of the toning stage number DC1 is the lighting of only the first LED 11, the toning correlation color temperature CCT is the first correlation color temperature CT1 (2700K), and the toning correlation color of the toning stage number DC10. Since the temperature CCT is the lighting of only the second LED 12, the toning correlated color temperature CCT is the second correlated color temperature CT2 (6500K).

  The relationship between the toning stage number DCn and the toning correlated color temperature CCT will be further described. For example, the toning correlation color temperature CCT of the toning stage number DC2 is 3122K. The toning correlation color temperature CCT (mixed color correlation color temperature) at the toning stage number DCn is obtained by a weighted average of the first driving current Idw and the second driving current Idc. For example, in the light control stage number LC2 and the toning stage number DC2, the first drive current Idw = 80 mA and the second drive current Idc = 10 mA. Therefore, the toning correlation color temperature CCT is (2700 × 80 + 6500 × 10) / (80 + 10) = 28100/90 = 3122K. That is, the toning correlation color temperature CCT is controlled by controlling the ratio between the first drive current Idw and the second drive current Idc.

  Note that the data storage unit 24 stores the first drive current Idw (current value) and the second drive current Idc (current value) in association with the dimming stage number LCm and the toning stage number DCn. Accordingly, when the dimming stage number LCm and the toning stage number DCn are designated, the drive control unit 23 reads the corresponding first drive current Idw and second drive current Idc from the data storage unit 24, and the first drive circuit 13 and The second drive circuit 14 is controlled.

  In the present embodiment, for example, when dimming and toning corresponding to the dimming stage number LC10 and the toning stage number DC2 are designated, the first drive current Idw = 8.89 mA and the second drive current Idc = 1.11 mA. Is defined in advance. The second drive current Idc (second drive current Idcu) = 1.11 mA is smaller than the specific current value Iu (2 mA). Therefore, when the second drive current Idcu is supplied to the second LED 12 as a direct current, the light emission state cannot be normally controlled. Specifically, a phenomenon has been found in which the toning correlated color temperature CCT changes greatly with respect to the value 3122K at the toning stage number DC2.

  Therefore, in the present embodiment, the second drive current Idcu (1.11 mA) is supplied by applying PWM to the specific current value Iu (2 mA). Specifically, the second drive current Idcu obtained by applying a duty ratio of (1.11 mA / 2 mA) × 100 (%) = 55.5% and applying a PWM of 0.555 to the DC current of 2 mA 2Supply to LED12.

  In addition, when light adjustment and color adjustment corresponding to the color adjustment stage number DC10 and the color adjustment stage number DC9 are designated, the first drive current Idw = 1.11 mA and the second drive current Idc = 8.89 mA are defined in advance. . The first drive current Idw (first drive current Idwu) = 1.11 mA is smaller than the specific current value Iu (2 mA). Accordingly, when the first drive current Idwu is supplied to the first LED 11 as a direct current, the light emission state cannot be normally controlled. Specifically, a phenomenon has been found in which the toning correlated color temperature CCT changes greatly with respect to the value 6078K at the toning stage number DC9.

  Therefore, in the present embodiment, the first drive current Idwu (1.11 mA) is supplied by applying PWM to the specific current value Iu (2 mA). Specifically, the second drive current Idwu obtained by applying a duty ratio of (1.11 mA / 2 mA) × 100 (%) = 55.5% and applying a PWM of 0.555 to the DC current of 2 mA is used as the second drive current Idwu. 1 LED 11 is supplied.

  Note that the first drive current Idw and the second drive current Idc are changed, for example, linearly in both directions of the toning stage number DCn and the dimming stage number LCm, as shown below.

  For example, the first drive current Idw is divided into nine equal parts between the toning stage number DC1 and the toning stage number DC10 in the horizontal direction of the chart (the toning stage number DCn). Specifically, it typically appears in the following value at the light control stage number LC2.

  In the light adjustment stage number LC2, the first drive current Idw is 90 mA in the toning stage number DC1, 80 mA in the toning stage number DC2,..., 50 mA in the toning stage number DC5, 40 mA in the toning stage number DC6,. 10 mA is specified for the color stage number DC9 and 0 mA is specified for the toning stage number DC10. In addition, the second drive current Idc is equally divided into nine similarly to the first drive current Idw, but the transition state of the increase / decrease is reversed. That is, the second drive current Idc is 0 mA for the toning stage number DC1, 10 mA for the toning stage number DC2,..., 40 mA for the toning stage number DC5, 50 mA for the toning stage number DC6,. For 80 mA and the toning stage number DC10, 90 mA is defined.

  In the vertical direction of the chart (the light control stage number LCm), the method for defining the first drive current Idw and the second drive current Idc is the same, and the description thereof is omitted.

  FIG. 5A shows the dimming rate (the dimming stage number LCm) versus the dimming level at the toning stage number DC1 when the dimming control and the toning control are performed by the first drive current Idw and the second drive current Idc shown in FIG. It is a graph which shows the state of color correlation color temperature CCT.

  Since the minimum value of the dimming control is 0%, the second LED 12 is completely turned off at the toning stage number DC1. Therefore, the first correlated color temperature CT1 (2700K) is maintained as the toned correlated color temperature CCT in the entire range of the dimming stage number LCm (the dimming rate of 100% to the dimming rate of 10%).

  FIG. 5B shows the dimming rate (the dimming stage number LCm) versus the dimming level when the dimming control and the toning control are performed by the first driving current Idw and the second driving current Idc shown in FIG. It is a graph which shows the state of color correlation color temperature CCT.

  In the toning stage number DC2, the toning correlated color temperature CCT obtained by the weighted average of the first driving current Idw and the second driving current Idc with respect to the first correlated color temperature CT1 and the second correlated color temperature CT2 is 3122K.

  In the toning stage number DC2, when the dimming rate is 10%, the second drive current Idc supplied to the second LED 12 is smaller than the specific current value Iu (2 mA). However, since PWM is applied to the specific current value Iu and the second drive current Idcu (1.11 mA) is supplied to the second LED 12, the entire range of the dimming stage number LCm (the dimming rate 100% to the dimming rate 10). %), The toning correlation color temperature CCT = 3122K is maintained.

  FIG. 5C shows the dimming rate (the dimming stage number LCm) versus the dimming level at the toning stage number DC5 when the dimming control and the toning control are performed by the first driving current Idw and the second driving current Idc shown in FIG. It is a graph which shows the state of color correlation color temperature CCT.

  In the toning stage number DC5, the toning correlated color temperature CCT obtained by the weighted average of the first driving current Idw and the second driving current Idc with respect to the first correlated color temperature CT1 and the second correlated color temperature CT2 is 4389K.

  In the toning stage number DC5, when the dimming rate is 10%, the first drive current Idw supplied to the first LED 11 is 5.56 mA, and the second drive current Idc supplied to the second LED 12 is 4.44 mA. It is. Accordingly, the toning correlation color temperature CCT is maintained at the toning correlation color temperature CCT = 4389K in the entire range of the dimming stage number LCm (the dimming rate of 100% to the dimming rate of 10%).

  FIG. 5D shows the dimming rate (the dimming stage number LCm) versus the dimming level at the toning stage number DC6 when the dimming control and the toning control are performed by the first drive current Idw and the second drive current Idc shown in FIG. It is a graph which shows the state of color correlation color temperature CCT.

  In the toning stage number DC6, the toning correlated color temperature CCT obtained by the weighted average of the first driving current Idw and the second driving current Idc with respect to the first correlated color temperature CT1 and the second correlated color temperature CT2 is 4811K.

  In the toning stage number DC6, when the dimming rate is 10%, the first drive current Idw supplied to the first LED 11 is 4.44 mA, and the second drive current Idc supplied to the second LED 12 is 5.56 mA. It is. Therefore, the toning correlation color temperature CCT is maintained at 4811K in the entire range of the dimming stage number LCm (the dimming rate 100% to the dimming rate 10%).

  FIG. 5E shows the light adjustment stage number LCm versus the color adjustment correlated color temperature CCT at the color adjustment stage number DC9 when the light adjustment control and the color adjustment control are performed by the first drive current Idw and the second drive current Idc shown in FIG. It is a graph which shows the state of.

  In the toning stage number DC9, the toning correlated color temperature CCT obtained by the weighted average of the first driving current Idw and the second driving current Idc with respect to the first correlated color temperature CT1 and the second correlated color temperature CT2 is 6078K.

  In the toning stage number DC9, when the dimming rate is 10%, the first drive current Idw supplied to the first LED 11 is smaller than the specific current value Iu (2 mA). However, since the first drive current Idwu (1.11 mA) is supplied to the first LED 11 by applying PWM to the specific current value Iu, the entire range of the dimming stage number LCm (the dimming rate 100% to the dimming rate 10). %), The toning correlation color temperature CCT = 6078K is maintained.

  FIG. 5F illustrates the light adjustment stage number LCm versus the color adjustment correlated color temperature CCT at the color adjustment stage number DC10 when the light adjustment control and the color adjustment control are performed by the first drive current Idw and the second drive current Idc illustrated in FIG. It is a graph which shows the state of.

  Since the minimum value of the dimming control is 0%, the first LED 11 is completely turned off at the toning stage number DC10. Therefore, the second correlated color temperature CT2 (6500K) is maintained for the toned correlated color temperature CCT in the entire range of the dimming stage number LCm (the dimming rate 100% to the dimming rate 10%).

  As described above, as illustrated in FIG. 4 and FIGS. 5A to 5F, in the lighting device 1 according to the present embodiment, when the dimming control is performed based on the designated brightness (the dimming level LCm), or The current values (first drive current Idw, second drive current Idc) supplied to the LEDs (first LED and second LED) when toning control is performed based on the designated correlated color temperature (toning stage number DCn) When a current smaller than the specific current value Iu is supplied with the specific current value Iu specified in advance as a boundary, a direct current having the specific current value Iu is subjected to pulse width modulation (PWM) to drive current (first drive current) Idw, second drive current Idc), and when a current greater than or equal to the specific current value Iu is supplied, a direct current is supplied. It is possible to stably adjust the brightness and correlated color temperature by suppressing the influence due to the characteristics (variation), and to perform the dimming control and the toning control in a wide range with high accuracy and effectively. . That is, according to the lighting apparatus 1 according to the present embodiment, even when the brightness is controlled, the correlated color temperature does not change and deep light control is possible.

  Next, comparative examples are shown in FIGS. 6 and 7A to 7D. A case where the minimum value of dimming control is set to 2%, for example, for the lighting apparatus 1 according to Embodiment 1 of the present invention will be described as a comparative example.

  FIG. 6 shows, as a comparative example, the dimming stage number LCm, the toning stage number DCn, the first drive current Idw, the first dimming stage number when the minimum value of dimming control is set for the lighting apparatus 1 according to Embodiment 1 of the present invention. It is a graph which shows the correlation of 2 drive current Idc and toning correlation color temperature CCT.

  Since the basic configuration is as shown in FIG. 4, different items will be mainly described.

  In FIG. 6, the minimum value of the dimming control is set to 2%, and 2% as the minimum value is secured when the LED in which the first LED 11 or the second LED 12 is smaller is in the toning control or dimming control. The control form is turned on.

  For example, in the toning stage number DC1, as shown in FIG. 4, in the dimming stage number LC1, the first driving current Idw = 100 mA and the second driving current Idc = 0 mA. On the other hand, in FIG. 6, the first drive current Idw = 98 mA and the second drive current Idc = 2 mA (minimum value of dimming control) are maintained at the toning stage number DC1 and at the dimming stage number LC1.

  Therefore, in the dimming control and the toning control, there is an influence due to the minimum value 2% (2 mA) of the dimming control. Specifically, in the toning stage number DC1, changes in the first driving current Idw, the second driving current Idc, and the toning correlated color temperature CCT from the dimming stage number LC1 to the dimming stage number LC10 are as follows: It becomes difficult to stabilize the toned correlated color temperature CCT.

  In the toning stage number DC1, in the toning stage number LC1, the first driving current Idw = 98 mA and the second driving current Idc = 2 mA (minimum value of the dimming control), and the toning correlation is performed by the same weighted average as in FIG. The color temperature CCT is 2776K. In the light control stage number LC2, the first drive current Idw = 88 mA, the second drive current Idc = 2 mA, and the toning correlation color temperature CCT = 2784K. In the light control stage number LC3, the first drive current Idw = 78 mA, the second drive current Idc = 2 mA, and the toning correlation color temperature CCT = 2799K. .... In the light control stage number LC10, the first drive current Idw = 8 mA, the second drive current Idc = 2 mA, and the toning correlation color temperature CCT = 3460K.

  That is, since the second drive current Idc = 2mA is fixed at the toning stage number DC1, the first driving current Idw is reduced from 98 mA (the dimming stage number LC1), and the first driving current Idw = 8 mA (the dimming stage number LC10). When the value decreases to the first LED 11, the lighting state of the second LED 12 cannot be ignored, and the toned correlated color temperature CCT approaches the second correlated color temperature CT2.

  In the toning stage number DC5, in the dimming stage number LC1, the first driving current Idw = 55.33 mA, the second driving current Idc = 44.67 mA, and the toning correlation color temperature CCT = 4397K. .... In the light control stage number LC10, the first drive current Idw = 5.33 mA, the second drive current Idc = 4.67 mA, and the toning correlation color temperature CCT = 4473K.

  That is, in the toning stage number DC5, the toning correlation color temperature CCT in the case of the dimming stage number LC10 is 4473K with respect to the toning correlation color temperature CCT in the case of the dimming stage number LC1, and the toning correlation color temperature CCT is set to It cannot be secured to a certain level. The influence of the minimum value of the dimming control set as 2% increases as the dimming stage number LCm decreases, and the toning correlated color temperature CCT approaches the second correlated color temperature CT2.

  In the toning stage number DC10, in the dimming stage number LC1, the first driving current Idw = 2 mA (minimum value of dimming control) and the second driving current Idc = 98 mA, and the toning correlation is performed by the same weighted average as in FIG. Color temperature CCT = 6424K. In the light control stage number LC2, the first drive current Idw = 2 mA, the second drive current Idc = 88 mA, and the toning correlation color temperature CCT = 6416K. In the light control stage number LC3, the first drive current Idw = 2 mA, the second drive current Idc = 78 mA, and the toning correlation color temperature CCT = 6405K. .... In the light control stage number LC10, the first drive current Idw = 2 mA, the second drive current Idc = 8 mA, and the toning correlation color temperature CCT = 5740K.

  That is, at the toning stage number DC10, the first driving current Idw is fixed at 2 mA, so the second driving current Idc is reduced from 98 mA (the dimming stage number LC1), and the second driving current Idc = 8 mA (the dimming stage number LC10). When the value decreases to the second LED 12, the lighting state of the first LED 11 cannot be ignored, and the toned correlated color temperature CCT approaches the first correlated color temperature CT1.

  In the toning stage number DC6, in the dimming stage number LC1, the first driving current Idw = 44.67 mA, the second driving current Idc = 55.33 mA, and the toning correlation color temperature CCT = 4803K. .... In the light control stage number LC10, the first drive current Idw = 4.67 mA, the second drive current Idc = 5.33 mA, and the toning correlation color temperature CCT = 4727K.

  In other words, in the toning stage number DC6, the toning correlation color temperature CCT in the case of the dimming stage number LC10 is 4727K with respect to the toning correlation color temperature CCT in the case of the dimming stage number LC1, and thus, It cannot be secured to a certain level. The influence of the minimum value of the dimming control set as 2% increases as the dimming stage number LCm decreases, and the toning correlated color temperature CCT approaches the first correlated color temperature CT1.

  FIG. 7A illustrates the dimming rate (the dimming stage number LCm) versus the dimming level when the dimming control and the toning control are performed using the first driving current Idw and the second driving current Idc illustrated in FIG. It is a graph which shows the state of color correlation color temperature CCT.

  As described above, the toning correlation color temperature CCT is affected by the second LED 12 that is always lit at a minimum value of 2%, and the toning correlation color temperature CCT is equal to the second correlation color temperature CT2 as the dimming rate is reduced from 100% to 10%. It is not possible to secure a constant toned correlation color temperature CCT.

  FIG. 7B illustrates the dimming rate (the dimming stage number LCm) versus the dimming level when the dimming control and the toning control are performed using the first drive current Idw and the second drive current Idc illustrated in FIG. It is a graph which shows the state of color correlation color temperature CCT.

  As in the case of FIG. 7B, there is an influence by the second LED 12, but the absolute value of the change in the toning correlation color temperature CCT is small.

  FIG. 7C shows the dimming rate (the dimming stage number LCm) versus the dimming at the toning stage number DC6 when the dimming control and the toning control are performed by the first driving current Idw and the second driving current Idc shown in FIG. It is a graph which shows the state of color correlation color temperature CCT.

  Contrary to the case of FIG. 7B, there is an influence by the first LED 11, but the absolute value of the change in the toning correlation color temperature CCT becomes small.

  FIG. 7D shows the dimming rate (the dimming stage number LCm) versus the dimming level at the toning stage number DC10 when the dimming control and the toning control are performed by the first drive current Idw and the second drive current Idc shown in FIG. It is a graph which shows the state of color correlation color temperature CCT.

  As described above, the toned correlated color temperature CCT is affected by the first LED 11 that is always lit at the minimum value of 2%, and the toned correlated color temperature CCT is equal to the first correlated color temperature CT1 as the dimming rate is reduced from 100% to 10%. It is not possible to secure a constant toned correlation color temperature CCT.

  Also in this comparative example, the first drive current Idw at the toning stage number DC1 is not 2 mA but 0 mA as in FIG. 4, and the toning stage number DC10 second drive current Idc is not 2 mA but the same as in FIG. If the current is 0 mA, the toned correlated color temperature CCT can be brought into a state in which the correlated color temperature does not change at the toned stage number DCn. However, when the visibility was actually examined, there was a problem that the correlated color temperature flew too much when the toning stage number DC1 was shifted to the toning stage number DC2. As a measure for improvement, in the comparative example, in the toning stage number DC1 and the toning stage number DC10, the LED on the side having the opposite correlated color temperature is driven with a small current. It has been.

1 lighting device 11 first LED
12 Second LED
DESCRIPTION OF SYMBOLS 13 1st drive circuit 14 2nd drive circuit 20 Control part 20b Bus 21 Specification signal input part 22 Specification signal determination part 23 Drive control part 24 Data storage part 30 Remote controller BS Reference potential line CCT Toning correlation color temperature CT1 1st correlation Color temperature CT2 Second correlated color temperature DC1 to DC10 Toning stage number (specified correlated color temperature)
DCn Toning stage number Idc second drive current Idcu second drive current (smaller than specific current value Iu)
Idw first drive current Idwu first drive current (smaller than a specific current value Iu)
Iu specific current value LC1 to LC10 Number of dimming steps (specified brightness)
LCm Dimming Stage Number OP1 First Operational Amplifier OP2 Second Operational Amplifier Pm1 Modulation Pulse Pm2 Modulation Pulse PS1 DC Power Supply Q11 First Switching Element Q12 Third Switching Element Q21 Second Switching Element Q22 Fourth Switching Element R1 First Current Detection Element R2 Second current detection element Tin1 First non-inverting input terminal Tin2 First inverting input terminal Tin3 Second non-inverting input terminal Tin4 Second inverting input terminal Vref1 First reference voltage Vref2 Second reference voltage VS1 First reference voltage source VS2 Second Reference voltage source

Claims (7)

A first LED that emits light at a first correlated color temperature, a first drive circuit that supplies a first drive current to the first LED, a second LED that emits light at a second correlated color temperature, and a second drive current to the second LED A lighting device comprising: a second drive circuit to be supplied; and a drive control unit that controls the first drive circuit and the second drive circuit,
The current value of the first drive current and the current value of the second drive current are defined in advance corresponding to the brightness and correlated color temperature of each of the first LED and the second LED to be controlled,
When the brightness and the correlated color temperature are specified,
The current value of the first drive current corresponding to the specified brightness and the correlated color temperature is smaller than a specific current value specified in advance as a lower limit value of a stable DC current based on the light emission characteristics of the first LED. The first drive circuit generates the first drive current corresponding to the specified brightness and the correlated color temperature by performing pulse width modulation on the direct current having the specific current value at the H level. Supplying the first LED;
When the current value of the first drive current corresponding to the specified brightness and the correlated color temperature is larger than the specific current value, the first drive circuit is configured to specify the specified brightness and the correlated color temperature. Generating the first drive current of the direct current corresponding to the first LED and supplying the first drive current to the first LED,
The current value of the second drive current corresponding to the designated brightness and the correlated color temperature is smaller than a specific current value specified in advance as a lower limit value of a stable DC current based on the light emission characteristics of the second LED. The second drive circuit generates the second drive current corresponding to the specified brightness and the correlated color temperature by performing pulse width modulation on the direct current that sets the specific current value to the H level. Supplying the second LED;
When the current value of the second drive current corresponding to the specified brightness and the correlated color temperature is greater than the specific current value, the second drive circuit is configured to specify the specified brightness and the correlated color temperature. The illumination device is configured to generate the second drive current having a direct current corresponding to the above and supply the second drive current to the second LED. The lighting device according to claim 1,
The lighting device according to claim 1, wherein the specific current value is specified in advance based on a light emission characteristic of the first LED and a light emission characteristic of the second LED. The lighting device according to claim 1 or 2,
The first LED and the second LED are connected in parallel between a DC power source and a reference potential line,
The first drive circuit includes:
A first current detection element having one end connected to the reference potential line; a first switching element connected between the other end of the first current detection element and the first LED; a first non-inverting input terminal; A first operational amplifier having a first inverting input terminal for controlling on / off of the first switching element; and a first reference voltage source for inputting a first reference voltage to the first non-inverting input terminal, A potential at a connection point between the first current detection element and the first switching element is input to the first inverting input terminal of the first operational amplifier;
The second driving circuit includes:
A second current detecting element having one end connected to the reference potential line, a second switching element connected between the other end of the second current detecting element and the second LED, a second non-inverting input terminal, A second operational amplifier having a second inverting input terminal for controlling on / off of the second switching element; and a second reference voltage source for inputting a second reference voltage to the second non-inverting input terminal, The lighting device, wherein a potential at a connection point between the second current detection element and the second switching element is input to the second inverting input terminal of the second operational amplifier. The lighting device according to claim 3,
The drive control unit controls the first reference voltage of the first reference voltage source corresponding to the first drive current supplied to the first LED, and corresponds to the second drive current supplied to the second LED. And controlling the second reference voltage of the second reference voltage source. The lighting device according to claim 3 or 4,
A third switching element connected between the reference potential line and the first non-inverting input terminal of the first operational amplifier; the reference potential line and the second non-inverting input terminal of the second operational amplifier; And a fourth switching element connected between the lighting devices. It is an illuminating device as described in any one of Claim 1- Claim 5, Comprising:
The lighting device according to claim 1, wherein the first correlated color temperature is a warm color system, and the second correlated color temperature is a cold color system. It is an illuminating device as described in any one of Claim 1- Claim 6, Comprising:
The first LED is a first LED group including a plurality of LEDs having the same specification, and the second LED is a second LED group including a plurality of LEDs having the same specification.

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