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 box and a plurality of light emitting diodes mounted on the box. The electric track supplies the lamps with power to light the light emitting diodes. The driver provides the controlling capability on light quantity, quality, frequency and duty ratio.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part application of U.S. patent application Ser. No. 09/837,170, filed Apr. 19, 2001, now U.S. Pat. No. 6,474,838. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to an artificial lighting apparatus using light emitting diodes as a light source for young plants, especially plantlets growing in tissue culture vessels. 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, easy decay, fixed light quality, short life span and flickering. Light emitting diodes (LEDs) have no excess heat problem; thus, LEDs can be arranged very close to the cultured plant to save space. In addition, LEDs have the advantages of a long life span and low power consumption. Therefore, research in culturing plants with LEDs has been proceeding. In 1992, Hoenecke, et al. successfully cultured vegetables by using 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 prior research was 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, referred to as LEDsets, are detachably mounted on the electric track. Each of the LEDset includes a mounting box and at least one type of light emitting diode mounted on the box. The electric track supplies the LEDsets with power to light the 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 LEDset 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. 6A is a block diagram of a driver of the artificial lighting apparatus of the present invention. 
     FIG. 6B is a block diagram of the circuit in FIG.  6 A. 
     FIG. 7 depicts another arrangement of LEDs on a circuit board of the LEDset of the present invention. 
     FIG. 8 depicts another arrangement of LEDs on a circuit board of the LEDset of the present invention. 
    
    
     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 . 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 the photoperiod. A photoperiod of 16/8 indicates an exposure to the light for 16 hours daily. The first number is the duration in hours of the light period and the second number is the duration in hours of the dark period for every 24-hour period. The driver  16  is used to adjust 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 . First LEDs  121  and second LEDs  122  are alternately mounted on the circuit board  126 . The first LEDs  121  are spaced apart the same distance. The first LEDs  121  can be red LEDs, blue LEDs, infrared LEDs or white LEDs. Similarly, the second LEDs  122  are spaced at the same distance. The second LEDs  122  can also be red LEDs, blue LEDs, infrared LEDs or white LEDs. It is therefore understood that the first LEDs  121  and the second LEDs  122  can be the same or be different. If the first LEDs  121  and the second LEDs  122  are different, then the first LEDs  121  and the second LEDs  122  require different voltages, thus requiring four wires in total to supply power. However, the present invention uses a common ground wire for the first LEDs  121  and the second LEDs  122 , thereby reducing the number of wires to three. Referring to FIG. 2, the first LEDs  121  and the second LEDs  122  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. 4 is a perspective diagram of the electric track of the present invention, with a cutaway 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  supplies 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 the 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, and the carrier wave for the waveform 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. 
     FIG. 7 depicts another arrangement of LEDs on a circuit board of the LEDset of the present invention, wherein reference numeral  1210  represents the first LEDs,  1220  the second LEDs and  1230  the third LEDs. The first LEDs  1210  can be red LEDs, blue LEDs, infrared LEDs or white LEDs. The second LEDs  1220  can be red LEDs, blue LEDs, infrared LEDs or white LEDs. Also, the third LEDs  1230  can be red LEDs, blue LEDs, infrared LEDs or white LEDs. 
     FIG. 8 depicts another arrangement of LEDs on a circuit board of the LEDset of the present invention, wherein reference numeral  1210  represents the first LEDs,  1220  the second LEDs,  1230  the third LEDs and  1240  the fourth LEDs. The first LEDs  1210  can be red LEDs, blue LEDs, infrared LEDs or white LEDs. The second LEDs  1220  can be red LEDs, blue LEDs, infrared LEDs or white LEDs. The third LEDs  1230  can be red LEDs, blue LEDs, infrared LEDs or white LEDs. Also, the fourth LEDs  1240  can be red LEDs, blue LEDs, infrared LEDs or white LEDs. 
     Furthermore, it is understood that the above-mentioned LEDs include laser diodes. That is, laser diodes are a category of LEDs. 
     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 plant lets. 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 optimum 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 LEDsets of the present invention are designed so that their mounting and dismounting on the electric tracks is fast and easy, representing a great advantage to the construction of a new plant factory and 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.