Abstract:
An artificial lighting apparatus for young plants that includes at least one electric track and a plurality of lamps. The lamps are detachably mounted on the electric track. Each of the lamps includes a plurality of first light emitting diodes, a plurality of second light emitting diodes and a mounting box. The first and second light emitting diodes are alternately arranged. The electric track supplies the lamps with power to light the first and second light emitting diodes. The driver provides the controlling capability on light quantity, quality, frequency and duty ratio.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to an artificial lighting apparatus using high intensity red and blue light emitting diodes as a mixed light source for young plants, especially the plantlets growth in tissue culture vessel. During the lightperiod provided to the plant, the light quantity, light quality, duty ratio and frequency of the mixed light source of the present invention are adjustable. 
     2. Description of the Related Art 
     In the past, tubular fluorescent lamps (TFLs) were used as artificial light sources in plant tissue culture. However, TFL has problems including heat generation, easily decay, fixed light quality, short life span and flickering. Light emitting diodes (LEDs) have no excess heat problem so that LEDs can be arranged very close to the cultured plant to save culturing space. In addition, LEDs have the advantages of a long life span and low power consumption. Therefore, the research in culturing plants with LEDs has been proceeding. In 1992, Hoenecke, et al. successfully cultured vegetables by high intensity red LEDs (Hoenecke, M. E., R. J. Bula, and T. W. Tibbitts, 1992, Importance of ‘Blue’ photon levels for lettuce seedlings grown under red-light-emitting diodes, HortScience 27 (5) :427-430). In 1993, blue LEDs were successfully developed. In 1996, Okamoto et al. used high intensity red LEDs and blue LEDs to culture plants, with the quantum ratio of 2:1 for red light/blue light (Okamoto, K., T. Yanagi and S. Takita, 1996, Development of plant growth apparatus using blue and red LED as artificial light source, Acta Hort., 440 :111-116). Also in 1996, Yanagi et al. used blue LEDs (170 μmol/m 2 /s) to culture lettuce (Yanagi, T., K. Okamoto and S. Takita, 1996, Effects of blue, red and blue/red lights of two different PPF levels on growth and morphogenesis of lettuce plants, Acta Hort, 440 :117-122). The dry weight of the cultured lettuce using pure blue light was less than that of the lettuce cultured by pure red light or red/blue light. Nevertheless, the cultured lettuce was short and healthy. 
     SUMMARY OF THE INVENTION 
     All the prior researches were made on a small scale, while the present invention is provided for the purpose of mass production. The present invention provides a plant-growing bench including at least one electric track and a plurality of lamps. The lamps, named LEDsets, are detachably mounted on the electric track. Each of the LEDset includes a first type of light emitting diodes, a second type of light emitting diodes and a mounting box. The two types of light emitting diodes are alternately arranged. The electric track supplies the LEDsets with power to light the light emitting diodes. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
     FIG. 1 is a perspective diagram of a plant-growing bench equipped with the present invention and related controlling device. 
     FIG. 2 is a perspective diagram of a LEDset of the present invention. 
     FIG. 3 depicts an arrangement of LEDs on a circuit board of the lamp of the present invention. 
     FIG. 4 is a perspective diagram of a 3-wire electric track of the present invention, which is modified from a commercially available 2-wire electric track. 
     FIG. 5 depicts the 3-wire electric track of the present invention with LEDsets mounted thereon. 
     FIG. 6 is a block diagram of a driver of the artificial lighting apparatus of the present invention. 
     FIGS. 7 a - 7   c  show wiring diagrams to the arrangement of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a plant-growing bench  1  of the present invention can be partitioned into a plurality of layers. On the ceiling of each layer are mounted 3-wire electric tracks  11 , while on each 3-wire electric track  11  are mounted LEDsets  12 . Each LEDset  12  is a mixed light source including high intensity red and blue LEDs mounted on a circuit board attached to a box. Cultured plantlets  2  are provided in tissue culture vessels  2  under the LEDset  12 . Furthermore, a timer  13 , a switch  14 , an AC/DC converter  15  and several drivers  16  are mounted on a sideboard of the plant-growing bench  1 . The AC/DC converter  15  supplies the LEDsets  12  with power through the 3-wire electric tracks  11  to illuminate the plantlets in the vessels  2 . The switch  14  is used for manually turning on/off the power. When the power is on, the timer  13  is used for the control of photoperiod. A photoperiod of {fraction (16/8)} means turn on the light for 16 hours daily. The first number is the duration hours of the light period and the second number is the duration hours of the dark period. The driver  16  is used for adjusting the voltage, current, frequency and duty ratio by the direct current provided to the LEDsets  12 , thereby controlling the light quantity, light quality and lighting cycle of the LEDsets  12  during the light-period. The LEDsets  12 , electric tracks  11  and driver  16  are described in detail as follows. 
     Referring to FIGS. 2 and 3, the LEDset  12  has a mounting box  120  and a circuit board  126  on the box  120 . High intensity red LEDs  122  and blue LEDs  121  are alternately mounted on the circuit board  126 . The blue LEDs  121  are spaced apart by the same distance. Similarly, the high intensity red LEDs  122  are spaced at the same distance apart. It is understood that lighting the high intensity red LEDs  122  and lighting the blue LEDs  121  require different voltages, thus requiring four wires in total to supply power. However, the present invention uses a common ground wire for the high intensity red LEDs  122  and the blue LEDs  121 , thereby reducing the number of wires to three. Referring to FIG. 2, the high intensity red LEDs  122  and the blue LEDs  121  are connected to three wires  123 ,  125 ,  127  through the circuit board  126  and connector  128 , wherein the wires  123 ,  125  are power lines and the wire  127  is the common ground line. Furthermore, an operating handle  124  and a locking element  129  are mounted on the box  120  of the LEDset  12 . When the user pushes the operating handle  124  in direction A, the locking element  129  is rotated in direction B. Two electrodes  123 ′,  125 ′ are provided on the locking element  129  and electrically connected to the wires (power lines)  123 ,  125 . 
     FIG. 7 a  is a wiring diagram showing a connection of anodes for red LEDs. Each anode “+“ of the red LEDs  122  is connected to the power line  123 . FIG. 7 b  is a wiring diagram showing a connection of anodes from blue LEDs. Each anode + of the blue LEDs  121  is connected to the power line  125 . FIG. 7 c  is a wiring diagram showing a connection of cathodes for red and blue LEDs. Each cathode “−” of the red and blue LEDs  122  and  121  are connected to the common ground line  123 . 
     FIG. 4 is a perspective diagram of the electric track of the present invention, wherein a portion of the electric track is cut away to show the inside of the electric track. The electric track  11  has an elongated body  111  and a pair of longitudinal engaging grooves  112 ,  112 ′ and receiving grooves  114 ,  114 ′ provided in the body  111 . Bare copper wires  113 ,  115  are received in the receiving grooves. An elongated cover  118  is fixed to the body  118 . The common ground wire  117  is received in the cover  118  and laterally connected to a plurality of connectors  116  outside the cover  111 . 
     FIG. 5 depicts the electric track with LEDsets mounted thereon. The electric track  11  and the LEDsets  12  are assembled together in the following manner: 
     (1) The user puts the locking element  129  of the LEDset  12  in the electric track  11  and then pushes the handle  124  of the LEDset  12  to rotate the locking element  129  so that the LEDset  12  and the electric track  11  are locked together by the locking element  129 . The electrodes  123 ′,  125 ′ of the LEDset  12  follow the locking element  129  to rotate and then physically contact the bare copper wires  113 ,  115 . 
     (2) The user connects the ground wire  127  of the LEDset  12  to the connector  116  of the electric track  11 . 
     Then, the electric track  11  can supply the LEDset  12  with power. 
     Referring to FIG. 6, the driver  16  includes a waveform generating and controlling circuit  161  and a current amplifying circuit  162 . The waveform generating and controlling circuit  161  outputs desired waveform (e.g. square waves, triangular waves, sine waves, cosine waves and pulses, etc.). Also, the waveform&#39;s amplitude, frequency and duty ratio are adjustable by the waveform generating and controlling circuit  161 . Then, the waveform is amplified by the current-amplifying circuit  162  and sent to the LEDset  12  to control the LEDs&#39; light quantity and lighting cycle. The current of different types of LEDs can be controlled separately, thus controlling the light quality. 
     The plant-growing bench of the present invention is developed for the purpose of mass-production. The plant-growing bench is partitioned into a plurality of layers. On the ceiling of each layer are mounted electric tracks, while on each electric track are mounted LEDsets for simultaneously culturing a large quantity of plantlets. Furthermore, the user can individually control the LEDs&#39; light quantity, light quality and lighting cycle via the driver. Therefore, the plant-growing bench of the present invention is adapted for culturing various kinds of plantlets, wherein the best growth conditions for each are different. Furthermore, researchers can use the plant-growing bench of the present invention to find the best light quantity and light quality for the growths of various plantlets, and to assess the acceptable lighting cycles for saving the electric power and enhancing the photosynthetic efficiency. Furthermore, the lamps of the present invention are well designed so that mounting and dismounting the LEDsets on the electric tracks are fast and easy. That is of great advantage to the construction of a new plant factory and the maintenance of an existing plant factory. 
     While the invention has been described by way of example and in terms of the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.