Abstract:
A solar simulator combines mercury lamps and halogen lamps, to improve upon conventional solar simulators using halogen and infrared lamps which cannot recreate an environment close to that under real sunlight, and upon solar simulators using expensive and fragile metal halide lamps and arc xenon lamps. An environment recreation laboratory for solar simulation includes a lamp bank mounted at an upper portion thereof and including a plurality of halogen lamps, halogen filter lamps being halogen lamps provided with an infrared filter, respectively, and mercury lamps. A temperature control unit includes a cooling unit that discharges air to cool the lamp bank, and an air conditioner that distributes the air discharged by the cooling unit. An electrical panel controls operations of the lamp bank and the temperature control unit, such that an environment within the environment recreation laboratory may very closely simulate the environment under real sunlight.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a solar simulator, and particularly, to a solar simulator using a combination of mercury and halogen lamps so as to be capable of providing an environment with an illumination and a temperature approximating daily changes of radiated sunlight by combining commercial mercury lamps, halogen lamps and halogen filter lamps having an infrared filter.  
         [0003]     2. Description of the Background Art  
         [0004]     In general, an environment recreation laboratory (testing room) is installed indoors. In the environment recreation laboratory, performance and durability of a subject to be tested (sample) is examined within an environment approximating the natural environmental conditions. In order to successfully carry out the performance and durability test on various goods and weapons, equipment for an environment recreation test, which is arranged within the environment recreation laboratory, should be able to recreate conditions approximating the natural environment as much as possible.  
         [0005]     A solar simulator, a lighting device arranged in the environment recreation laboratory, uses a halogen lamp or an infrared lamp to simulate sunlight. However, the halogen lamp and the infrared lamp cannot create all the wavelengths of sunlight. Therefore, to improve the accuracy of the environment recreation test, it is better to perform the test under conditions of actual sunlight than in the environment recreation laboratory.  
         [0006]     Also, some solar simulators simulate the spectral wavelengths of sunlight by using a metal-halide lamp or an arc xenon lamp, but are problematic for several reasons: expensive lamps and difficult manipulation.  
       SUMMARY OF THE INVENTION  
       [0007]     Therefore, it is an object of the present invention to provide a solar simulator using a combination of mercury and halogen lamps, which has a lamp bank in which commercial lamps are properly arranged to emit light, closely simulating sunlight, and which can approximate a daily change of sunlight radiated during a day by controlling a temperature and an irradiance within an environment recreation laboratory provided with the lamp bank.  
         [0008]     Another object of the present invention is to provide a lamp bank that can simulate sunlight to provide the moderns who spend the most time indoors, with an environment similar to that under the real sunlight.  
         [0009]     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a solar simulator using a combination of mercury lamps and halogen lamps in an environment recreation laboratory for solar simulation, the solar simulator comprising: a lamp bank mounted at an upper portion of an environment recreation laboratory and including a plurality of halogen lamps, a plurality of mercury lamps and a plurality of halogen filter lamps being halogen lamps provided with infrared filters, respectively; a temperature control unit including a cooling unit that discharges air for removing high temperature heat generated by the lamp bank, and an air conditioner that distributes the air discharged by the cooling unit to the lamp bank; and an electrical panel for controlling operations of the lamp bank and the temperature control unit.  
         [0010]     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a lamp bank including a plurality of halogen lamps, a plurality of mercury lamps and a plurality of halogen filter lamps being halogen lamps provided with infrared filters, respectively, wherein the plurality of halogen filter lamps are arranged at a central portion thereof, the plurality of halogen lamps are arranged outwardly of the plurality of halogen filter lamps, and the plurality of mercury lamps are arranged outwardly of the plurality of halogen lamps.  
         [0011]     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a unit of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.  
         [0013]     In the drawings:  
         [0014]      FIG. 1  illustrates a perspective view of an environment recreation laboratory implementing a solar simulator in accordance with the present invention;  
         [0015]      FIG. 2  is a top plan view which illustrates a lamp bank comprising the solar simulator of the environment recreation laboratory in accordance with the present invention;  
         [0016]      FIG. 3  is a side elevation view which illustrates an interipr of the environment recreation laboratory implementing the solar simulator in accordance with the present invention;  
         [0017]      FIG. 4A  illustrates a further side elevation view of the interior of the environment recreation laboratory implementing the solar simulator in accordance with the present invention;  
         [0018]      FIG. 4B  schematically illustrates a first electrical panel of the solar simulator in accordance with the present invention; and  
         [0019]      FIGS. 5A and 5B  are graphs respectively showing irradiance profiles for actual sunlight and for light produced by the solar simulator in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0021]      FIG. 1  illustrates a perspective view of an environment recreation laboratory to which the solar simulator in accordance with the present invention is applied. As shown, the environment recreation laboratory includes a lamp bank  10  installed at an upper portion of the environment recreation laboratory and emitting light with three wavelengths, simulating sunlight, a cooling unit  30  for outputting cool air for removing high temperature heat generated by the lamp bank  10 , an air conditioner  20  for dispensing the cool air outputted from the cooling unit  30 , first, second and third electrical panels  40 ,  50  and  60  for controlling the lamp bank  10 , the air conditioner  20  and the cooling unit  30 , and a perforated plate  70  arranged on the same plane with the lamp bank.  
         [0022]     A plurality of halogen lamps, halogen filter lamps and mercury lamps are arranged in a specific order so that the lamp bank  10  may create spectrums of infrared light, visible light and ultraviolet light, simulating sunlight.  
         [0023]     The air conditioner  20  and the cooling unit  30  control the temperature within the environment recreation laboratory to create a desired environment, and remove the high temperature heat generated by the lamp bank  10  to extend a life span of each lamp.  
         [0024]     To control an irradiance within the environment recreation laboratory, the first, second and third electrical panels  40 ,  50  and  60  control ON/OFF operation of each lamp constituting the lamp bank  10 . Also, to control the temperature, those panels control the air conditioner  20  and the cooling unit  30 .  
         [0025]     The perforated plate  70  is installed on the same horizontal plane as the lamp bank  10 , and has small holes so as to prevent the cool air from the air conditioner, which is discharged from a position that is higher than that of the lamp bank  10 , from falling to the floor before flowing to the lamp bank  10 .  
         [0026]      FIG. 2  illustrates an arrangement of a lamp bank in the environment recreation laboratory implementing the solar simulator in accordance with the present invention. Referring to  FIG. 2 , the lamp bank  10  includes commercially available halogen filter, halogen and mercury lamps  11 ,  12  and  13 .  
         [0027]     Here, the lamp bank  10  is constructed by a combination of those lamps  11 ,  12  and  13  in order to obtain irradiance values of infrared light, visible light and ultraviolet light regions, closely approximating sunlight.  
         [0028]     In the case of the spectrum of light emitted by a halogen lamp, an irradiance value increases from a shorter wavelength to a longer wavelength. In contrast, the spectrum of actual sunlight has an irradiance decreased from a shorter wavelength to a longer wavelength. Therefore, if only halogen lamps  12  are used, the irradiance value is low at the ultraviolet light region and is large at the infrared light region, as compared to sunlight.  
         [0029]     Therefore, mercury lamps  13  are arranged to compensate a deficient irradiance at the ultraviolet light region. Also, halogen filter lamps  11  are used to decrease an irradiance at the infrared light region. Here, the halogen filter lamp  11  is a halogen lamp  12  provided with an infrared filter, thereby decreasing the amount of ultraviolet light emitted from the halogen lamp  12 .  
         [0030]     The lamp bank  10  should satisfy a condition of maintaining uniformity of the irradiance within the target area as well as a condition of having an irradiance per wavelength approximating that of sunlight. To this end, the halogen lamps  10  and the halogen filter lamps  11 , the locations of which influence the uniformity of irradiance within the target area, are arranged at a central portion of the lamp bank  10 , and the mercury lamps  13  whose locations have no influence on the uniformity of irradiance are arranged at an outer edge. In order that the lamp bank  10  emits an amount of infrared light approximating natural sunlight, the halogen filter lamps  11  are arranged inwardly of the halogen lamps.  
         [0031]     Specifically, to determine the shape of the lamp bank  10 , the x-axis coordinate and the y-axis coordinate of each lamp constituting the lamp bank  10  is calculated upon inputting to an existing simulation program, data about the distance (H 0 ) between a target or a sample (i.e., a subject to be tested) and the center of a center lamp, the intervals between lamps in both the line and column directions, longitudinal and horizontal lengths of the lamp bank, the number of lamps in both the line and column directions and a zenithal angle. In the present invention, the lamp bank  10  is set to be arranged on a plane parallel to the sample by setting the zenithal angle of the input data as 0°. The reason why the lamp bank  10  is set to be arranged on a plane parallel to the sample is that if the lamp bank  10  is not parallel thereto and has a zenithal angle which is not 0°, the columns are gathered at the center of the zenithal angle. Accordingly, the z coordinate of the lamp bank  10  becomes H 0 , and the x-axis and y-axis coordinates are obtained as the simulation program calculates input data about the intervals between lamps in both the line and column directions, longitudinal and horizontal lengths of the lamp bank and the number of lamps in both the line and column directions.  
         [0032]     According to one embodiment of the present invention, the halogen filter lamps  11 , the halogen lamps  12  and the mercury lamps  13  constituting the lamp bank  10  may be disposed as illustrated in  FIG. 2 , respectively. The irradiance in each wavelength range (spectrum), obtained by experiment, is shown in the following Table 1.  
                                         TABLE 1                                   Wavelength range (μm)   Irradiance (W/m 2 )                                        0.28-0.40   52.9           0.40-0.78   466           0.78-3.00   587                      
 
         [0033]     Namely, as shown in Table  1 , the total irradiance was measured at 1106 W/m 2  within a range of ±10% of 112  0 W/m 2 . Also, from the experiment, it can be known that the illumination within a defined area (60 cm×60 cm) is uniform within the range of ±10% of 1120 W/m 2 .  
         [0034]     The perforated plate  70  is provided on the same plane as the lamp bank  10 , and the size of the holes in the perforated plate  70  is smaller than the interval between the lamps constituting the lamp bank  10 . The perforated plate  70  is formed so as to enable a large amount of the air discharged from the air conditioner  20  to reach the lamp bank  10 . Namely, the perforated plate  70  having the small holes is arranged in order to prevent the denser cool air, which is discharged to a ceiling portion of the environment recreation laboratory from the air conditioner  20 , from descending before reaching the lamp bank  10 . Therefore, a large amount of cooling air can pass through the lamp bank  10 .  
         [0035]      FIG. 3  illustrates an interior of the environment recreation laboratory equipped with the solar simulator in accordance with the present invention. As illustrated, a sample is placed at the center of an area onto which light is emitted from the lamp bank  10  of the environment recreation laboratory. Also, the lamps arranged towards the outer edges are inclined inwardly at predetermined angles toward the center, i.e., towards the sample.  
         [0036]     In the environment recreation laboratory, the air conditioner  20  and the cooling unit  30  for dispersing high temperature heat are arranged, thereby preventing a life span reduction of the lamps due to an increase in the temperature of the lamp bank  10 . The cooling unit  30  includes a compressor, a condenser and a capillary tube, and a fluid refrigerant condensed in the cooling unit  30  is gasified in an evaporator  23  within the air conditioner  20  and discharged through a blower  21 . A heater  22  within the air conditioner  20  controls a temperature of a gaseous refrigerant evaporated by the evaporator  23 .  
         [0037]      FIG. 4A  schematically illustrates a side view of the environment recreation laboratory equipped with the solar simulator in accordance with the present invention. As illustrated, first, second and third electrical panels  40 ,  50  and  60  for respectively controlling the lamp bank  10 , the air conditioner  20  and the cooling unit  30  are provided at a side portion of the environment recreation laboratory.  
         [0038]      FIG. 4B  schematically illustrates a frontal elevation view and a left side elevation view. As illustrated, the first electrical panel  40  includes a blower/cooling unit operation indicator lamp  41  for indicating whether the blower  21  and cooling unit  30  are in operation based upon the lamp&#39;s lighting state, a blower/cooling unit operating switch  42  for operating the blower  21  and the cooling unit  30 , a controller  43  storing reference values for controlling the blower  21  and the cooling unit  30  and reference values for controlling ON/OFF operation of the lamp bank  10 , the controller  43  being responsible for a temperature and irradiance control in accordance with internal signals and a time signal, an irradiance display unit  44 , a temperature display unit  45 , a humidity display unit  46  and a wind velocity display unit  47  for measuring and displaying the irradiance, the temperature, the humidity and the wind velocity of the recreated environment, and a recorder  48  for recording changes in the irradiance, temperature, humidity and wind velocity in the environment recreation laboratory.  
         [0039]     The controller  43  stores irradiance reference values and temperature reference values from sunrise to sunset to control the temperature and the irradiance, and controls the irradiance and the temperature within the environment recreation laboratory on the basis of the stored irradiance and temperature values.  
         [0040]     As one embodiment, a controller made by OYO (model:U-6622P-CH3) may be used, and as the recorder  48 , a commercially available model μR1800 made by YOKOGAWA may be used.  
         [0041]     The second electrical panel  50  includes a lamp lighting checking unit  51  and a lamp switch  52 . The second electrical panel  50  controls ON/OFF operation of each lamp of the lamp bank  10  and simultaneously checks a lighting state of each lamp.  
         [0042]     As an example, a control process in accordance with the present invention to recreate the environment of a region undergoing an air temperature change from 30° C. to 44° C. and an irradiance change from 0 W/m 2  to 1120 W/m 2  during a day will now be described.  
         [0043]     First, an irradiance variation and a temperature variation of the region to be recreated are inputted to the controller  43  and then power is inputted. Then, power is distributed to the lamp bank  10 , the air conditioner  20 , the cooling unit  30  and the first, second and third electrical panels  40 ˜ 60 , and the controller  43  of the first electrical panel  40  controls the irradiance within the environment recreation laboratory in accordance with the time signal.  
         [0044]     Here, the time signal is divided into four levels. The time signal effectively controls the lamp bank, by virtue of the fact that as the level of the time signal increases, more lamps are turned on. Lamps turned on when the time signal corresponds to an upper level (e.g., third level) include those lamps turned on when the time signal corresponds to a lower level (e.g., second level). Also, the time signal at each level turns on at least one halogen filter lamp, one halogen lamp and one mercury lamp.  
         [0045]     In one embodiment, it is set that a first level time signal is applied to the controller for one and one-half hours after sunrise, a second level time signal is applied for the next one and one-half hours, a third level time signal is applied for the next two hours, and a fourth level time signal is applied from 11:00 to 15:00 during which interval the irradiance and temperature are the highest. As the simulated daytime gets closer to sunset, the level of the time signal decreases. In order to realize an environment more closely simulating irradiance variation of the corresponding region, the time signal may have more minutely divided levels over time.  
         [0046]     Also, the controller  43  controls the air conditioner  20  and the cooling unit  30  such that the room temperature measured by a temperature sensor (not shown) arranged within the environment recreation laboratory approaches the reference temperature value.  
         [0047]     The third electrical panel  60  has therein a mercury lamp stabilizer (not IS shown) for maintaining a constant voltage of each mercury lamp  13 , thereby maintaining a constant irradiance.  
         [0048]      FIGS. 5A and 5B  illustrate graphs showing irradiance profiles for actual sunlight and for light produced by the solar simulator in accordance with the present invention.  FIG. 5A  is a graph showing the irradiance profile for actual sunlight of an area, which is to be recreated by the present invention, to show changes in temperature and irradiance during the day. Referring to the graph, the air temperature is changed from 30° C. to 44° C. during the day, and the irradiance is changed from 0W/m 2  to 1120W/m 2 .  FIG. 5B  is a graph showing temperature and irradiance changes within the environment recreation laboratory equipped with the solar simulator in accordance with the present invention. As the controller  43  controls the lamp bank  10 , the air conditioner  20  and the cooling unit  30 , a profile that is very similar to the graph of  FIG. 5A  can be obtained.  
         [0049]     As so far described, by the present invention, an environmental condition within the environment recreation laboratory very closely simulates the environment produced by natural sunlight. The effects of the present invention will now be described.  
         [0050]     First, without being affected by geographical and seasonal factors, a test using simulated solar energy can be performed under the conditions of a temperature of 49° C. and an irradiance of 1120 Wm2, which are typical of harsh environmental conditions required for testing by the military. Secondly, an environment close to the natural environment can be realized even by using relatively inexpensive commercially available lamps. Thirdly, as the lamps are optimally arranged for the test, the radiation uniformity within a target area is maintained within ±10%, and the time and cost required for the test can be reduced by ⅓. Lastly, the lamp bank used for the solar simulator may also be utilized in other applications, for example, the moderns who spend little time outdoors can be provided with simulated natural light even when indoors.  
         [0051]     As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.