Abstract:
A refrigerator includes a storing unit for storing vegetables; a light emitting unit for irradiating light onto the vegetables stored in the storing unit to promote photosynthesis of the vegetables; an input unit for receiving an operation instruction on whether the light emitting unit is to be turned on or off; a timer for detecting a current time to output current time information; and a control unit for controlling the light emitting unit in response to the operation instruction. If the operation instruction requests that the light emitting unit be off, the control unit controls the light emitting unit to be off; and if otherwise, the control unit controls the light emitting unit to be on or off depending on the current time information.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a refrigerator capable of promoting photosynthesis of vegetables; and, more particularly, to a refrigerator capable of promoting photosynthesis of vegetables by emitting light onto vegetables stored therein in such as manner that the vegetables can be kept in an environment similar to the natural environment, thereby maintaining the freshness thereof. 
   BACKGROUND OF THE INVENTION 
   In general, the refrigerator includes a compressor, a condenser, an expansion valve and an evaporator to perform a cooling cycle, and thus keeps the freshness of food items for a long period of time by cold air generated through such a cooling cycle. 
   In such a refrigerator, a freezer compartment for preserving food items in a frozen state and a refrigerator compartment for preserving the food items in a refrigerated state are partitioned inside a main body forming external appearance thereof, so that the food items can be stored in either the refrigerator compartment or the freezer compartment according to the storage temperature of the food items. 
     FIG. 1  shows a configuration of a conventional refrigerator  10  whose refrigerator compartment is provided with a plurality of shelves  11  and a vegetable room  12  to separately store a large amount of food items such as vegetables or fruits therein. 
   Such a refrigerator keeps the vegetables stored therein at a low temperature by simply controlling the cold air, whereby the freshness of the vegetables can be maintained for a certain period of time. However, in case of preserving them for a long time, the freshness of the vegetables may not be maintained. 
   The vegetables, which belong to the plant kingdom, respire and transpire even while they are stored in a refrigerator. Therefore, in order to maintain the freshness of the vegetables stored in the refrigerator, it is necessary to suppress the respiration and the transpiration. 
   Accordingly, the conventional refrigerator can maintain a certain degree of freshness by keeping the vegetables at a low temperature to suppress the respiration and in a high humidity to prevent the transpiration. However, since the chlorophyll contained in the vegetables cannot be prevented from being decomposed, the freshness of the vegetables cannot be maintained due to a decrease in the concentration of chlorophyll contained in the vegetables with the lapse of a certain period of time. 
   SUMMARY OF THE INVENTION 
   In order to solve the above-mentioned problem, it is, therefore, an object of the present invention to provide a refrigerator capable of promoting photosynthesis of vegetables to maintain the freshness of the vegetables stored therein by installing a photosynthesis promotion unit in the refrigerator and controlling the photosynthesis promotion unit in such a manner that the photosynthesis occurs in the vegetables stored in the refrigerator under conditions similar to those of the natural environment. 
   In accordance with one aspect of the present invention, there is provided a refrigerator including a storing unit for storing vegetables; a light emitting unit for irradiating light onto the vegetables stored in the storing unit to promote photosynthesis of the vegetables; an input unit for receiving an operation instruction on whether the light emitting unit is to be turned on or off; a timer for detecting a current time to output current time information; and a control unit for controlling the light emitting unit in response to the operation instruction, wherein, if the operation instruction requests that the light emitting unit be off, the control unit controls the light emitting unit to be off; and if otherwise, the control unit controls the light emitting unit to be on or off depending on the current time information. 
   In accordance with another aspect of the present invention, there is provided a control method of a refrigerator including a storing unit for storing vegetables and a light emitting unit for emitting light onto the vegetables stored in the storing unit to promote photosynthesis of the vegetables, the method comprising the steps of: a first step of receiving an operation instruction on whether the light emitting unit is to be on or off; a second step of controlling the light emitting unit to be off if the operation instruction requests that the light emitting unit be off, and receiving current time information from a timer if the operation instruction requests that the light emitting unit be on; and a third step of controlling the light emitting unit to be on or off based on the current time information if the operation instruction requests that the light emitting unit be on. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and features of the present invention will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a perspective view for showing a conventional refrigerator; 
       FIG. 2  is a cross sectional view for illustrating a configuration of a refrigerator capable of promoting photosynthesis of vegetables in accordance with the present invention; 
       FIG. 3  is a block diagram for showing a configuration for controlling the photosynthesis of the vegetables stored in the refrigerator in accordance with the present invention; and 
       FIG. 4  is a flow chart for describing a process for controlling the photosynthesis of the vegetables stored in the refrigerator in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that they can be readily implemented by those skilled in the art. 
     FIG. 2  is a cross sectional view for illustrating a configuration of a refrigerator capable of promoting photosynthesis of vegetables in accordance with the present invention; and  FIG. 3  is a block diagram for showing a configuration for controlling the photosynthesis of the vegetables stored in the refrigerator in accordance with the present invention. 
   As shown therein, a refrigerator  100  in accordance with the present invention includes a main body  110  divided into a freezer compartment at an upper portion thereof and a refrigerator compartment at a lower portion thereof; one or more photosynthesis promotion units  200 , installed in the refrigerator compartment, for emitting light required for photosynthesis of vegetables; a timer  230  for providing time information to the photosynthesis promotion units  200  so that the photosynthesis promotion units  200  can operate according to a current time; and an input unit  240 . 
   In the main body  110 , a louver  120  is installed to form a duct for supplying air cooled in a cooling unit into the freezing and refrigerator compartments. In particular, the photosynthesis promotion units  200  are fixed to a front side of the louver  120  installed in the refrigerator compartment. 
   The louver  120  has at least one discharge opening  130  for discharging air cooled in the cooling unit to an inside of the refrigerator compartment, and at least one suction opening  140  for sucking the air which has exchanged heat with stuff stored in the refrigerator compartment. 
   The cold air supplied through the louver  120  keeps the vegetables stored in the refrigerator compartment at a low temperature, thereby suppressing respiration thereof. 
   The photosynthesis promotion units  200  are installed in an inner side surface or a backside surface of the main body  110  in such a manner that light can be emitted from the photosynthesis promotion units  200  to the vegetables stored in the refrigerator compartment. Here, the light is turned on or off depending on time; or the light intensity is adjusted such that the vegetables stored in the refrigerator compartment can perform photosynthesis under conditions similar to the natural environment. 
   To be more specific, each photosynthesis promotion unit  200  includes a control unit  210  for controlling the operation of the photosynthesis promotion units  200 ; and a light emitting unit  220  for emitting light. 
   The control unit  210  outputs signals for turning on and off the light emitting unit  220  and for adjusting the light intensity (brightness) of the light emitted from the light emitting unit  220 . 
   To be more specific, the control unit  210  compares a current time detected by the timer  230  to a reference time to determine whether the light emitting unit  220  should be turned on or off. If the detected current time is within daytime zone (for example, 7 a.m. to 7 p.m.), the control unit  210  outputs an ON signal to the light emitting unit  220 . On the contrary, the control unit  210  outputs an OFF signal to the light emitting unit  220  if the detected current time is within nighttime zone (for example, 7 p.m. to 7 a.m.). 
   Further, the control unit  210  may divide the daytime hours into a plurality of time zones. For example, the daytime zone may be divided into a first time zone (for example, 7 a.m. to 11 a.m.), a second time zone (for example, 11 a.m. to 3 p.m.) and a third time zone (for example, 3 p.m. to 7 p.m.), and the control unit  210  may adjust the light intensity of the light emitted by emitting unit  220  according to the time zones. 
   It is preferable that the control unit  210  is included in a refrigerator controller for controlling main operations of the refrigerator. 
   The light emitting unit  220 , configured with, e.g., a plurality of LEDs for emitting light having different wavelengths, is turned on and off in response to the control signal outputted from the control unit  210 . Further, as described above, the light intensity of the light emitted from the light emitting unit  220  may be adjusted by the control unit  210 . 
   More specifically, the light emitting unit  220  is configured with a first LED  221  and a second LED  222 . The wavelength of light emitted from the second LED  222  is different from that of first LED  221 , and the second LED  222  is disposed to be, e.g., adjacent to the first LED  221 . Preferably, the first LED  221  emits light whose wavelength is within a range from 600 to 650 nm, whereas the second LED  222  emits light whose wavelength is within a range from 450 to 500 nm. With this configuration, light of an appropriate wavelength can be supplied to the vegetables according to current states thereof (e.g., whether the vegetables are in a growth stage or a mature stage). 
   As described above, the vegetables stored in the refrigerator compartment can be supplied with light of an appropriate wavelength and an appropriate light intensity according to the time and the current states of the vegetables. Thus, biological or chemical processes that cause to deteriorate the freshness of vegetables can be suppressed. To be specific, the decomposition of chlorophyll contained in leaves of vegetables is suppressed. Thus, the decrease in the chlorophyll concentration is also suppressed to keep vegetables green in color. Further, the decrease in the amount of vitamin C contained in vegetables is also suppressed. Thus, vegetables can be kept fresh for a longer period of time, while maintaining the nutrients therein to be intact. 
   Meanwhile, although the photosynthesis promotion units  200  are preferably installed at an uppermost portion of the louver  120  so that light is irradiated downward from the upper portion of the refrigerator compartment, it is also possible to install some of the light emitting units  220  underneath the shelves that partitions the inside of the refrigerator compartment as shown in  FIG. 2 . 
   The timer  230 , which is a clock for example, serves to detect the current time to generate current time information for determining the turn-on or turn-off of the light emitting unit  220 , and the appropriate light intensity of the light emitted therefrom to be adjusted. Then, the current time information is inputted to the photosynthesis promotion units  200 . 
   The input unit  240  serves to receive operation instructions from a user of the refrigerator. The operation instructions include temperature selections of the freezer compartment and the refrigerator compartment; a selection of high-speed or normal refrigerating mode; and a selection of the turn-on or turn-off of the photosynthesis promotion units  200 . If one or more of the operation instructions of the photosynthesis promotion units  200  are inputted, the input unit  240  transfers the operation instructions to the control unit  210  as electrical signals. For example, if the operation instructions inputted from the input unit  240  request that the photosynthesis promotion units be turned on, the input unit  240  transmits a signal corresponding to this request to the control unit  210 . 
   Next, the operation of the refrigerator capable of performing the photosynthesis of vegetables will be described with reference to  FIGS. 3 and 4 . 
   When the refrigerator starts the operation, the operation instructions, which including temperature selections of the freezer compartment and the refrigerator compartment, a selection of high-speed or normal refrigerating mode and a selection of the turn-on or turn-off of the photosynthesis promotion units  200 , are inputted to the input unit  240  in step S 100 . 
   In step S 110 , it is checked whether the operation instructions, inputted in step  100 , request that the photosynthesis promotion units  200  be turned on or off. Then, if the operation instructions request that the photosynthesis promotion units  200  be turned on, the process is proceeded to step S 121 . In step S 121 , the control unit  210  controls the refrigerator to perform a cooling cycle is performed according to the operation instructions inputted from the input unit  240 , such that the temperatures of the freezer compartment and the refrigerator compartment are adjusted to the selected temperatures, and the refrigerating more is set to be the high-speed or normal refrigerating pursuant to the selection included in the operation instructions. 
   On the other hand, if the operation instructions inputted in step  100  request that the photosynthesis promotion units  200  be turned on, the process is proceeded to step S 120 . In step S 120 , the control unit  210  transmits a time request signal that requests the current time information to the timer  230 . In response thereto, the timer  230  detects the current time and transmits the current time information to the control unit  210 . 
   Further, it is preferable that information about the current states of the vegetables is also inputted to the input unit  240  in step S 110 , and, in response thereto, the control unit  210  selects the wavelength of the light in step S 120 . For example, if the vegetables are in a mature stage, a wavelength of 600 to 650 nm is selected. On the contrary, for example, if the vegetables are in a growth stage, a wavelength of 450 nm to 500 nm, which is required for early growths of vegetables, is selected. Accordingly, the vegetables can be supplied with light having an appropriate wavelength according to the current states of the vegetables. 
   Next, in step S 130 , if the current time is determined to be in the daytime zone based on the current time information provided from the timer  230 , the control unit  210  performs step S 141  to transmit a turn-on signal to turn on the photosynthesis promotion unit(s)  220  whose wavelength of light corresponds to the wavelength selected in step S 120 . However, if the current time is determined in step S 130  to be in the nighttime zone, the control unit  210  performs step S 141  to transmit a turn-off signal to turn off all of the photosynthesis promotion units  220 . 
   More specifically, in step S 140 , the control unit  210  compares the current time detected by the timer  230  to the reference time to determine whether the light emitting units  220  are to be turned on or off. If the detected current time is within daytime zone (for example, 7 a.m. to 7 p.m.), the control unit  210  outputs a turn-on signal to the light emitting units  220 , whereas it outputs a turn-off signal of the light emitting unit  220  if the detected current time is within nighttime zone (for example, 7 p.m. to 7 a.m.). 
   Preferably, in step S 140 , the control unit  210  outputs not only the turn-on and turn-off signals but also an intensity control signal for adjusting the light intensity of the light emitting unit  220 . To be specific, the control unit  210  divides the daytime zone into a plurality of time zones such as the following: the first time zone (for example, 7 a.m. to 11 a.m.), the second time zone (for example, 11 a.m. to 3 p.m.) and the third time zone (for example, 3 p.m. to 7 p.m.). Then, if the turn-on signal is to be transmitted to the light emitting units  220 , and if the detected current time is within a specified time zone (the first time zone, for example), the control unit  210  adjusts the light intensity of the light emitting units  220  to a preset level corresponding to that time zone (the first time zone, for example). 
   Herein, similarly to the natural environment, the preset level of light intensity is set to be higher around midday than the morning and afternoon hours. In this manner, the light conditions for the vegetables in the refrigerator compartment can be set to be similar to those in the natural environment, so that the vegetables can be kept fresh in the refrigerator. 
   As described above, in accordance with the present invention, light required for photosynthesis of vegetables can be supplied sufficiently into the refrigerator, and the light conditions for the vegetables in the refrigerator can be set to be similar to those in the natural environment. 
   Thus, since decomposition of chlorophyll of the vegetables can be suppressed, it is possible to maintain the freshness of the vegetables stored in the vegetable room of the refrigerator. 
   While the invention has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.