Abstract:
The present invention provides a color-mixing light-emitting diode module. According to the present invention, a first light-emitting chip and two second light-emitting chips are disposed on a holder. The first light-emitting chip emits red light and the plurality of second light-emitting chips emit white light. The red light and the white light are mixed, giving mixed light with high color rendering and brightness. Objects illuminated by the mixed light will exhibit colors closest to their original colors as perceived by eyes. Furthermore, by arranging the first and second light-emitting chips in matrix, the color rendering of the light-emitting diode module can be adjusted and improved.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a light-emitting diode (LED) module, and particularly to a color-mixing LED module. 
     BACKGROUND OF THE INVENTION 
     Technologies progress with each passing day. In the lighting technology, the advancement is especially significant. The LED technology has been developing actively in recent years. The emittable light spans visible light, infrared light, and ultraviolet light; the light intensity is also raised substantially. With the emergence of white LEDs, the development is gradually directed to lighting applications nowadays. 
     An LED is monochromatic light source. On the other hand, the white light (the sunlight) in the nature has a wide-band spectrum. Thereby, a single LED cannot emit light with multiple colors; other materials should be used as auxiliaries. In other words, it is impossible that a single LED emits white light. Instead, a white LED is formed by the monochromatic light composed of three primary colors, namely, red (R), green (G), and blue (B), or by converting the monochromatic light emitted by an LED into white light by using fluorescent powders. Then, the overall spectrum contains the spectra of the three primary colors, which stimulate the light sensing cell in human eyes and thus eliciting the sense of white light. 
     All of the popular white LEDs adopt a single light-emitting unit to emit light with shorter wavelength, such as blue or ultraviolet light. Then, by using phosphor, a portion or all of the light is converted to the light containing green and red light, which have longer wavelengths in spectrum. The conversion of wavelength of light is named fluorescence. Its principle is that after short-wavelengths photons (blue, violet, and ultraviolet light) are absorbed by electrons in the fluorescent material, the electrons are excited to a high-energy-level and unstable excited state. Afterwards, when the electrons return to the original levels, a part of the energy is dissipated in the form of heat, while the rest is released in the form of photons. Because the energy of the released photons is less than before, their wavelengths will be longer. In addition, during the conversion process, a portion of energy is converted to heat, which is energy loss. Thereby, the efficiency of such kind of white LEDs is lower. 
     Besides, although the current LED technology is advancing continuously, there are still many drawbacks. High-efficient LED chips are power consuming and elicit high temperature, resulting in waste of power as well as shortening in lifetime. Hence, improvements are required in heat dissipation and color rendering. Traditional bulbs and halogen lamps have superior color rendering; fluorescent tubes also have high color rendering. Illumination by light sources with low color rendering results in an abnormal feel of color. Moreover, it also harms vision and health. 
     Technical research and development are devoted to reinforcing color rendering. It is generally believed that artificial light sources should enable human eyes to percept colors with correctness, just as seeing objects in the sunlight. Thereby, good color rendering means closer to the real look of objects in the sunlight, while bad color rendering means distortion. If the colors seen in a certain light source are utterly identical to those seen in standard illumination, the general color rendering index (Ra) is defined as 100. Basically, values of the general color rendering index greater than Ra80 will satisfy higher lighting requirements for color visibility. Of course, depending on application scenes and purposes, the requirements can be different. This gauge is the color-rendering property of a light source and named as the general color rendering index. The general color rendering index is the difference between the colors of an object illuminated by a certain light source and a reference light source. 
     The present invention improves the drawbacks according to the prior art. According to the present invention, a first light-emitting chip and two second light-emitting chips are disposed on a holder for die bonding and wire bonding. The first light-emitting chip emits red light and the plurality of second light-emitting chips emit white light. The red light and the white light are mixed, giving a mixed light with high color rendering and brightness. Objects illuminated by the mixed light will exhibit colors closest to their original colors as perceived by eyes. 
     SUMMARY 
     In the structure of the light-source module in current LEDs, because the light emitted by the red LED chip will illuminate the green fluorescent powder inside the cover layer, the red light emitted by the red LED chip will be absorbed and sheltered by the green powder, leading to attenuation in intensity and hue. Consequently, the white light source generated by the light-source module of the LED cannot have good color rendering and brightness concurrently; the light-source module of the LED will be inferior in color rendering or brightness. Accordingly, an objective of the present invention is to provide a color-mixing LED module, which can maintain the intensity and hue of red light for enhancing color rendering and brightness of the mixed light source. Hence, the object of improving color rendering and brightness of the present invention can be achieved. 
     In order to achieve the main objective and effect described above, the present invention provides a color-mixing LED module, which mainly comprises a holder, a frame member, at least a first light-emitting chip, and at least two second light-emitting chips. The frame member is disposed on the holder and includes at least a frame for partitioning into a first accommodating space and two accommodating spaces. The first light-emitting chip is bonded in the first accommodating space and emits light with wavelength ranging from 590 nm to 700 nm. A piece of first sealing glue covers the light-emitting path of the first light-emitting chip. In addition, the plurality of second light-emitting chips are disposed on one side of the first light-emitting chip and bonded in the plurality of second accommodating spaces. A piece of second sealing glue covers the light-emitting path of the second light-emitting chips and contains red fluorescent powder. Besides, the first light-emitting chip and the plurality of second light-emitting chips are disposed on the holder in a one-to-two matrix. 
     Furthermore, the frame member is disposed on the holder and includes at least a frame for partitioning into a first accommodating space and two accommodating spaces. The first light-emitting chip is bonded in the first accommodating space and emits light with wavelength ranging from 590 nm to 700 nm. A piece of first sealing glue covers the light-emitting path of the first light-emitting chip. In addition, the plurality of second light-emitting chips are disposed on one side of the first light-emitting chip and bonded in the plurality of second accommodating spaces. A piece of second sealing glue covers the light-emitting path of the second light-emitting chips and contains red fluorescent powder and green fluorescent powder with a ratio between 1:2 and 1:50. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a three-dimensional structural diagram of the color-mixing LED module according to the first embodiment of the present invention; 
         FIG. 2  shows a cross-sectional structural diagram of the color-mixing LED module according to the second embodiment of the present invention; 
         FIG. 3  shows a schematic diagram of the light homogenizer of the color-mixing LED module according to the third embodiment of the present invention; 
         FIG. 4  shows a schematic diagram of the light guiding frame of the color-mixing LED module according to the fourth embodiment of the present invention; and 
         FIG. 5  shows a schematic diagram of multiple chips of the color-mixing LED module according to the fifth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In order to make the structure and characteristics as well as the effectiveness of the present invention to be further understood and recognized, the detailed description of the present invention is provided as follows along with embodiments and accompanying figures. 
     The present invention solves the drawback of inferior color rendering in the light emitted by LEDs according to the prior art by providing a color-mixing LED module, The main characteristic of the present invention is producing a mixed light with high color rendering. When the mixed light illuminates an object, the object will exhibit more realistic colors in human eyes. 
     Please refer to  FIG. 1 , which shows a three-dimensional structural diagram of the color-mixing LED module according to the first embodiment of the present invention. As shown in the figure, the color-mixing LED module according to the present invention mainly comprises a holder  10 , a frame member  20 , at least a first light-emitting chip  30 , and at least two second light-emitting chips  40 . 
     The frame member  20  is disposed on the holder  10  and includes at least a frame  210  for partitioning into a first accommodating space  220  and two accommodating spaces  230 . The first light-emitting chip  30  is bonded in the first accommodating space  220  and emits light with wavelength ranging from 590 nm to 700 nm. A piece of first sealing glue  310  covers the light-emitting path of the first light-emitting chip  30 . In addition, the plurality of second light-emitting chips  40  are disposed on one side of the first light-emitting chip  30  and bonded in the plurality of second accommodating spaces  230 . A piece of second sealing glue  410  covers the light-emitting path of the second light-emitting chip  40  and contains red fluorescent powder. Besides, the first light-emitting chip  30  and the plurality of second light-emitting chips  40  are disposed on the holder  10  in a one-to-two matrix. 
     Moreover, when the second light-emitting chips  40  emit blue light with wavelength ranging between 380 nm and 500 nm, the second sealing glue  410  further includes green fluorescent powder or yellow fluorescent powder. As the blue light passes through the second sealing glue  410 , white light is generated. The preferable wavelength of the blue light is between 450 nm and 500 nm. When the second light-emitting chips  40  emit ultraviolet (UV) light, the second sealing glue  410  further includes green fluorescent powder and blue fluorescent powder. As the UV light passes through the second sealing glue  410 , which contains red, green, and blue fluorescent powder, white light is generated. The UV light can be divided into three segments. UV-A includes wavelengths between 400 nm and 315 nm; UV-B includes wavelengths between 280 nm and 315 nm; and UV-C includes wavelengths between 200 nm and 280 nm. All these three segments can be used. By using the above structure, the light emitted by the second light-emitting chips  40  passes through the second sealing glue  410  and thus generating white light. There are many ways to emit white light. Several methods have been proposed in the above description. Nonetheless, the technology of emitting white light is not main technical characteristic of the present invention. Hence, the details will not be described. The white light described above further accompanies light emitting of the first light-emitting chip  30 . The first light-emitting chip  30  emits red light with a wavelength between 590 nm and 700 nm. The preferable wavelength of the red light is between 610 nm and 700 nm. By using the red light emitted by the first light-emitting chip  30  and the converted red light by the red fluorescent powder provided in the second sealing glue  410 , the purpose of improving color rendering and brightness of the mixed light can be achieved. 
     Please refer to  FIG. 2 , which shows a cross-sectional structural diagram of the color-mixing LED module according to the second embodiment of the present invention. As shown in the figure, likewise, according to the second embodiment of the present invention, the frame member  20  is disposed on the holder  10  and includes at least a frame  210  for partitioning into a first accommodating space  220  and two accommodating spaces  230 . The first accommodating space  220  is the same as the one according to the first embodiment. In addition, the second light-emitting chips are bonded in the second accommodating spaces  230 . The wavelength of the light emitted by the second light-emitting chips  40  ranges between 380 nm and 500 nm. A piece of second sealing glue  410  covers the light-emitting path of the second light-emitting chips  40  and contains red fluorescent powder and green fluorescent powder with a ratio between 1:2 and 1:50. 
     The same method as the first embodiment is used for bonding the second light-emitting chips  40  in the second accommodating spaces  230 . The second light-emitting chips  40  can emit blue or UV light. When the second light-emitting chips  40  emit blue light with a wavelength between 380 nm and 500 nm, the ratio of the red fluorescent powder to the green fluorescent powder described above is between 1:2 and 1:50. Preferably, the wavelength of the blue light is between 450 nm and 500 nm. When the second light-emitting chips  40  emit UV light, the second sealing glue  410  further includes blue fluorescent powder. The wavelength of the UV light is between 200 nm and 400 nm. By using the above structure, the light emitted by the second light-emitting chips  40  passes through the second sealing glue  410  and thus generating white light. The white light described above further accompanies light emitting of the first light-emitting chip  30 . The first light-emitting chip  30  emits red light with a wavelength between 590 nm and 700 nm. The preferable wavelength of the red light is between 610 nm and 700 nm. The light emitted by the first light-emitting chip  30  is mixed with the light emitted by the second light-emitting chips  40  for enhancing color rendering and brightness. In addition, by adjusting the ratio between the red and green fluorescent powder described above, the color temperature can be adjusted accordingly. 
     The first light-emitting chip  30  and the plurality of second light-emitting chips  40  according to the present invention are disposed on the holder  10 . The first light-emitting chip  30  and the plurality of second light-emitting chips  40  can be connected electrically using serial connection, parallel connection, or combination of serial and parallel connections, depending on the requirement of users. 
     Please refer to  FIG. 3 , which shows a schematic diagram of the light homogenizer of the color-mixing LED module according to the third embodiment of the present invention. As shown in the figure, the present invention makes use of the lower height of the frame  210  than the height of the frame member  20 . Besides, a sealing layer  60  is disposed inside the frame member  20 . The sealing layer  60  covers the first accommodating space  220 , the plurality of the second accommodating spaces  230 , and the frame  210 . The number of refractions of the light emitted by the first light-emitting chip  30  and the plurality of second light-emitting chips  40  is increased by passing through the sealing layer  60 , resulting in enhanced color uniformity. Thereby, the present invention provides the efficacy of improving color uniformity. 
     Please refer to  FIG. 4 , which shows a schematic diagram of the light guiding frame of the color-mixing LED module according to the fourth embodiment of the present invention. As shown in the figure, the material of the frame  210  according to the present invention can be semi-transparent, represented in dashed lines. The semi-transparency here can be further defined as when the frame  210  is illuminated by light with a wavelength longer than 450 nm, the transmissivity of the frame  210  is above 80% and less than 100%. By using the semi-transparent frame  210 , when the second light-emitting chip  40  emits blue light, the blue light passing through the second sealing glue  410 , which contains mixture of red and green fluorescent powder, can be mixed with the red light emitted by the first light-emitting chip  30  via the frame  210 . Thereby, the efficacy of uniformity and color mixing can be further enhanced. 
     Please refer to  FIG. 5 , which shows a schematic diagram of multiple chips of the color-mixing LED module according to the fifth embodiment of the present invention. As shown in the figure, the frame  210  is disposed on the holder  10  and partitions the frame  210  into at least a first accommodating space  220  and at least a second accommodating space  230 . Thereby, the first accommodating space  220  can bond one or multiple first light-emitting chips  30  and the second accommodating space  230  can bond one or multiple second light-emitting chips  40  as well. Thus, the light-emitting intensity of the first and second light-emitting chips  30 ,  40  can be controlled, respectively, which, in turn, enables adjustment of color temperature and hue to the requirement of users and achieving the efficacy of adjusting color temperature and hue. 
     To sum up, the present invention provides a color-mixing LED module. According to the present invention, the red light will not be sheltered or absorbed by green fluorescent powder; the intensity and hue will not be attenuated; and the color rendering and brightness of the light emitted by this structure is superior. The quantity, combination, arrangement (matrix arrangement), and electrical connection of the first and second light-emitting chips can be altered with flexibility according to users&#39; requirements. In addition, the frame  210  can be varied in height, reflectivity, and transmissivity according to requirements. These are quite different from the formal cup design according to the prior art. 
     Accordingly, the present invention conforms to the legal requirements owing to its novelty, nonobviousness, and utility. However, the foregoing description is only embodiments of the present invention, not used to limit the scope and range of the present invention. Those equivalent changes or modifications made according to the shape, structure, feature, or spirit described in the claims of the present invention are included in the appended claims of the present invention.