Abstract:
A light-emitting device includes a dimmer, a rectifier, a first light-emitting module, a first controller, a second light-emitting module and a second controller. The dimmer is coupled to an alternating current for modulating the alternating current into an alternating signal. The rectifier couples the dimmer to the alternating current for rectifying the alternating signal into a direct current signal. The first light-emitting module is for emitting a first light with a first color temperature. The first controller is coupled to the first light-emitting module for controlling the first light-emitting module to emit the first light. The second light-emitting module is for emitting a second light with a second color temperature different from the first color temperature. The second controller coupled to the second light-emitting module for controlling the second light-emitting module to emit the second light.

Description:
[0001]    This application claims the benefit of Taiwan application Serial No. 105102060, filed Jan. 22, 2016, the subject matter of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    Field of the Invention 
         [0003]    The invention relates in general to a light emitting device and a light emission control method thereof, and more particularly to a light emitting device capable of controlling color temperature and a light emission control method thereof. 
         [0004]    Description of the Related Art 
         [0005]    Normally, the light emitted from the conventional light emitting device has one single color temperature only. However, the emission of the light with one single color temperature can only create one single scenario and can only be used in similar environments, hence limiting the application fields of the light emitting device. 
         [0006]    Therefore, it has become a prominent task for the industries to provide a new light emitting device capable of expanding the application fields of the light emitting device. 
       SUMMARY OF THE INVENTION 
       [0007]    The invention is directed to a light emitting device and a light emission control method thereof capable of expanding the application fields of the light emitting device. 
         [0008]    According to an embodiment of the present invention, a light emitting device is provided. The light emitting device includes a light modulator, a rectifier, a first light emitting module, a first controller, a second light emitting module and a second controller. The light modulator couples an alternating current (AC) and further modulates the alternating current to generate an alternating current dimming signal. The rectifier couples the light modulator and the alternating current and converts the alternating current dimming signal into a direct current dimming signal. The first light emitting module emits a first light with a first color temperature. The first controller couples the first light emitting module and is configured to control the first light emitting module to emit the first light, wherein the brightness of the first light varies with the change in the direct current dimming signal. The second light emitting module emits a second light with a second color temperature, wherein the first color temperature and the second color temperature are different. The second controller couples the second light emitting module and is configured to control the second light emitting module to emit the second light, wherein the brightness of the second light does not vary with the change in the direct current dimming signal. 
         [0009]    According to another embodiment of the present invention, a light emission control method is provided. The light emission control method includes following steps. A light emitting device is provided, wherein the light emitting device includes a light modulator, a rectifier, a first light emitting module, a first controller, a second light emitting module and a second controller; the light modulator couples an alternating current and modulates the alternating current to generate an alternating current dimming signal; and the rectifier couples the light modulator and the alternating current and converts the alternating current dimming signal into a direct current dimming signal. The first light emitting module is controlled to emit a first light by the first controller, wherein the brightness of the first light varies with the change in the direct current dimming signal. The second light emitting module is controlled to emit a second light by the second controller, wherein the brightness of the second light does not vary with the change in the direct current dimming signal. 
         [0010]    The above and other aspects of the invention will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment (s). The following description is made with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a functional block diagram of a light emitting device according to an embodiment of the invention. 
           [0012]      FIG. 2  is a circuit diagram of he light emitting device of  FIG. 1 . 
           [0013]      FIGS. 3A and 3B  are relationship diagrams of the irradiating power of the first light emitting element and the dimming rate of the light modulator of  FIG. 2 . 
           [0014]      FIGS. 4A and 4B  are relationship diagrams of the irradiating power of the second light emitting element and the dimming rate of the light modulator of  FIG. 2 . 
           [0015]      FIG. 5  is a functional block diagram of a light emitting device according to the invention another embodiment. 
           [0016]      FIG. 6  is a circuit diagram of the light emitting device of  FIG. 5 . 
           [0017]      FIG. 7A and 7B  are relationship diagrams of the irradiating power of the first light emitting element and the dimming rate of the light modulator of  FIG. 6 . 
           [0018]      FIG. 8A and 8B  are relationship diagrams of the irradiating power of the second light emitting element and the dimming rate of the light modulator of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Refer to  FIGS. 1 and 2 .  FIG. 1  is a functional block diagram of a light emitting device  100  according to an embodiment of the invention.  FIG. 2  is a circuit diagram of the light emitting device  100  of  FIG. 1 . 
         [0020]    The light emitting device  100  includes a light modulator  110 , a rectifier  120 , a first light emitting module  130 , a first controller  140 , a second light emitting module  150 , a second controller  160  and a third controller  170 . In an embodiment, the light modulator  110 , the rectifier  120 , the first light emitting module  130 , the first controller  140 , the second light emitting module  150 , the second controller  160  and the third controller  170  can be integrated in a circuit board  10  to form a driver on board (DOB) structure, but the embodiment of the invention is not limited thereto. In another embodiment, at least one of the light modulator  110 , the rectifier  120 , the first light emitting module  130 , the first controller  140 , the second light emitting module  150 , the second controller  160  and the third controller  170  can be integrated in the circuit board  10 . For example, the first light emitting module  130 , the first controller  140  and the third controller  170  can be integrated in the circuit board  10 . Or, the second light emitting module  150  and the second controller  160  can be integrated in the circuit board  10 . 
         [0021]    The light modulator  110  couples the alternating current  11  and modulates the alternating current  11  to generate an alternating current dimming signal S 1 ′. The rectifier  120  couples the light modulator  110  and the alternating current  11  and converts the alternating current dimming signal S 1 ′ into a direct current dimming signal S 1 . The first light emitting module  130  emits a first light L 1  with a first color temperature. The first controller  140  couples the first light emitting module  130  through the third controller  170  and controls the first light emitting module  130  to emit the first light L 1 , wherein the brightness of the first light L 1  varies with the change in the direct current dimming signal. The second light emitting module  150  emits a second light L 2  with a second color temperature. The first color temperature and the second color temperature are different. The second controller  160  couples the second light emitting module  150  and controls the second light emitting module  150  to emit a second light L 2 , wherein the brightness of the second light L 2  does not vary with the change in the direct current dimming signal S 1 . Thus, the light emitting device  100  can emit lights with different color temperatures under different dimming rates. In an embodiment, the second color temperature is, for example, 2700 K, and the first color temperature is, for example, 3000 K. 
         [0022]    As indicated in  FIG. 2 , the first light emitting module  130  includes a plurality of first light emitting elements  131  controlled by the third controller  170 . The third controller  170  controls different quantities of first light emitting elements  131  to emit the first light L 1  according to the change in the dimming rate of the light modulator  110 . For example, the higher the dimming rate of the light modulator  110 , the larger the quantity of first light emitting elements  131  can be controlled by the third controller  170  to emit the first light L 1  and increase the brightness of the first light L 1 . 
         [0023]    As indicated in  FIG. 2 , the second light emitting module  150  includes a plurality of second light emitting elements  151  controlled by the second controller  160  to emit the second light L 2 . 
         [0024]    Additionally, the first light emitting element  131  and the second light emitting element  151  can be realized by light emitting diodes (LED). The color temperature of the first light L 1  of the first light emitting element  131  can be higher than that of the second light L 2  of the second light emitting element  151 . In terms of quantity, the quantity of the first light emitting element  131  can be larger than the quantity of the second light emitting element  151 . For example, the quantity of the first light emitting element  131  is  20 , and the quantity of the second light emitting element  151  is 6, but the embodiment of the invention is not limited thereto. 
         [0025]    The relationship between the irradiating power of the first light emitting element  131  and the irradiating power of the second light emitting element  151  and the dimming rate of the light modulator  110  is further exemplified below. 
         [0026]    Referring to  FIG. 3A and 3B , relationship diagrams of the irradiating power of the first light emitting element  131  and the dimming rate of the light modulator  110  of  FIG. 2  are shown. As indicated in  FIG. 3A , the magnitude of the direct current dimming signal S 1  is proportional to the dimming rate of the light modulator  110 . As indicated in  FIG. 3A and 3B , the first predetermined value W 2  of the curve C 1  of  FIG. 3B  corresponds to the low dimming rate W 1  of  FIG. 3A . When the light modulator  110  is under the low dimming rate W 1  (that is, the direct current dimming signal S 1  is lower than the first predetermined value W 2 ), such as under 10% or 50%, the irradiating power of the first light emitting element  131  is 0, and this implies that the first light emitting element  131  does not emit the first light L 1 . When the direct current dimming signal S 1  is higher than the first predetermined value W 2 , the irradiating power of the first light emitting element  131  is larger than 0, and this implies that the first light emitting element  131  emits the first light L 1 . As indicated in  FIG. 3B , the magnitude of the direct current dimming signal S 1  is proportional to the irradiating power of the first light emitting element  131 . That is, the larger the magnitude of the direct current dimming signal S 1 , the higher the emission luminance of the first light emitting element  131 . Conversely, the smaller the magnitude of the direct current dimming signal S 1 , the lower the emission luminance of the first light emitting element  131 . 
         [0027]    Referring to  FIG. 4A and 4B , relationship diagrams of the irradiating power of the second light emitting element  151  and the dimming rate of the light modulator  110  of  FIG. 2  are shown. The irradiating power of the second light emitting element  151  does not vary with the change in the direct current dimming signal S 1 . To put it in greater details, as long as the direct current dimming signal S 1  is larger than 0, the irradiating power of the second light emitting element  151  is larger than 0 and the irradiating power is fixed regardless what the magnitude of the direct current dimming signal S 1  is. 
         [0028]    In the present embodiment, the first color temperature of the first light L 1  can be higher than the second color temperature of the second light L 2 . Thus, when the dimming rate is low, for example, when the direct current dimming signal S 1  is lower than the first predetermined value W 2 , the light emitting device  100  can emit the second light L 2  with low color temperature. When the direct current dimming signal S 1  is equivalent to or higher than the first predetermined value W 2 , the light emitting device  100  can emit the second light L 2  with low color temperature and the first light L 1  with high color temperature at the same time. The irradiating power of the first light L 1  with high color temperature is proportional to the magnitude of the direct current dimming signal S 1 . 
         [0029]    As indicated in  FIG. 3B , the first predetermined value W 2  of the present embodiment is larger than 0. In another embodiment, the first predetermined value W 2  is substantially equivalent to 0. Under such design, as indicated in the curve C 2  of  FIG. 3B , the first light emitting element  131  can emit the first light L 1  with the first color temperature as long as the direct current dimming signal S 1  is higher than 0. The irradiating power of the first light emitting element  131  is proportional to the magnitude of the direct current dimming signal S 1 . 
         [0030]    Refer to  FIGS. 5 and 6 .  FIG. 5  is a functional block diagram of a light emitting device  200  according to the invention another embodiment.  FIG. 6  is a circuit diagram of the light emitting device  200  of  FIG. 5 . 
         [0031]    The light emitting device  200  includes a light modulator  110 , a rectifier  120 , a first light emitting module  130 , a first controller  140 , a second light emitting module  150 , a second controller  160 , a third controller  170 , a first circuit  210  and a second circuit  220 . In an embodiment, the light modulator  110 , the rectifier  120 , the first light emitting module  130 , the first controller  140 , the second light emitting module  150 , the second controller  160 , the third controller  170 , the first circuit  210  and the second circuit  220  can be integrated in a circuit board  10  to form a DOB structure, but the embodiment of the invention is not limited thereto. In another embodiment, at least one of the light modulator  110 , the rectifier  120 , the first light emitting module  130 , the first controller  140 , the second light emitting module  150 , the second controller  160 , the third controller  170 , the first circuit  210  and the second circuit  220  can be integrated in the circuit board  10 . For example, the first light emitting module  130 , the first controller  140 , the third controller  170  and the first circuit  210  can be integrated in the circuit board  10 . Or, the second light emitting module  150 , the second controller  160  and the second circuit  220  can be integrated in the circuit board  10 . 
         [0032]    The first circuit  210  couples the rectifier  120  and the first controller  140 . The first circuit  210  converts the direct current dimming signal S 1  into a first voltage signal A 1 . The first controller  140  controls the first light emitting element  13  of the first light emitting module  130  to emit or not to emit the first light L 1 , and controls the first color temperature of the first light L 1  according to the magnitude of the first voltage signal A 1 . In the present embodiment, the first circuit  210  is a resistor-capacitor circuit, such that the voltage of the converted first voltage signal A 1  is smaller than that of the direct current dimming signal S 1  and will not be too high to damage the controller. 
         [0033]    The second circuit  220  couples the rectifier  120  and the second controller  160 . The second circuit  220  converts the direct current dimming signal S 1  into a second voltage signal A 2 . The second controller  160  can control the second light emitting element  151  of the second light emitting module  150  to emit or not to emit the second light L 2 . In the present embodiment, the second circuit  220  is a resistor-capacitor circuit, such that the voltage of the converted second voltage signal A 2  is smaller than that of the direct current dimming signal S 1  and will not be too high to damage the controller. 
         [0034]    The relationship between the irradiating power of the first light emitting element  131  and the irradiating power of the second light emitting element  151  and the dimming rate of the light modulator  110  of  FIG. 6  is exemplified below. 
         [0035]    Referring to  FIG. 7A and 7B , relationship diagrams of the irradiating power of the first light emitting element  131  and the dimming rate of the light modulator  110   FIG. 6  are shown. As indicated in  FIG. 7A , the magnitude of the first voltage signal Al is proportional to the dimming rate of the light modulator  110 . As indicated in  FIGS. 7A and 7B , the second predetermined value W 3  of the curve C 1  of  FIG. 7B  corresponds to the low dimming rate W 1  of  FIG. 7A . When the light modulator  110  is under the low dimming rate W 1  (that is, the first voltage signal A 1  is lower than the second predetermined value W 3 ), such as under 10% or 50%, the irradiating power of the first light emitting element  131  is 0, and this implies that the first light emitting element  131  does not emit the first light L 1 . When the first voltage signal A 1  is higher than the second predetermined value W 3 , the irradiating power of the first light emitting element  131  is larger than 0, and this implies that the first light emitting element  131  emits the first light L 1 . As indicated in  FIG. 7B , the magnitude of the first voltage signal A 1  is proportional to the irradiating power of the first light emitting element  131 . That is, the larger the first voltage signal A 1  is, the higher the emission luminance of the first light emitting element  131  is. Conversely, the smaller the magnitude of the direct current dimming signal S 1  is, the lower the emission luminance of the first light emitting element  131  is. 
         [0036]    Referring to  FIG. 8A and 8B , relationship diagrams of the irradiating power of the second light emitting element  151  and the dimming rate of the light modulator  110  of  FIG. 6  are shown. The irradiating power of the second light emitting element  151  does not vary with the change in the second voltage signal A 2 . To put it in greater details, as long as the second voltage signal A 2  is larger than 0, the irradiating power of the second light emitting element  151  is larger than 0 and the irradiating power is fixed regardless what the magnitude of the second voltage signal A 2  is. 
         [0037]    In the present embodiment, the first color temperature of the first light L 1  is higher than the second color temperature of the second light L 2 . Thus, when the dimming rate is low, the light emitting device  100  still can emit the second light L 2  with low color temperature as long as the second voltage signal A 2  is higher than 0 although the first voltage signal A 1  is lower than the second predetermined value W 3 . When the first voltage signal A 1  is equivalent to or higher than the second predetermined value W 3 , the light emitting device  100  can emit the second light L 2  with low color temperature and the first light L 1  with high color temperature at the same time. The irradiating power of the first light L 1  with high color temperature is proportional to the magnitude of the first voltage signal A 1 . 
         [0038]    As indicated in  FIG. 7B , the second predetermined value W 3  of the present embodiment is larger than 0. In another embodiment, the second predetermined value W 3  is substantially equivalent to 0. Under such design, as indicated in the curve C 2  of  FIG. 7B , the first light emitting element  131  can emit the first light L 1  with the first color temperature as long as the first voltage signal A 1  is higher than 0. The irradiating power of the first light emitting element  131  is proportional to the magnitude of the first voltage signal A 1 . 
         [0039]    To summarize, the light emitting device of the embodiment of the invention can emit lights with different color temperatures according to different dimming rates, hence expanding the application fields of the light emitting device. To put it in greater details, the light emitting device of the embodiment of the invention can control the color temperature of the emitted light according to the environment. For example, when the dimming rate is low, the light emitting device can emit the light with a warmer color temperature. When the dimming rate is high, the light emitting device can emit the light with a colder color temperature. In an embodiment, the light emitting element of the light emitting device can be realized by light emitting diodes (LEDs), not only saving power but also providing different color temperatures to the emitted lights. In comparison to the conventional incandescent lamb, the light emitting device of the embodiment of the invention can save power consumption by at least 80% or 85%. 
         [0040]    While the invention has been described by way of example and in terms of the preferred embodiment (s), it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.