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  Grating and clean room system comprising the sameUSPTO Application #: 20060003684Title: Grating and clean room system comprising the same Abstract: Grating forming the floor of a clean room minimizes turbulence and enhances the rate at which air is discharged therethrough. The grate includes a base plate having a plurality of through-holes. Each of the through-holes includes a receiving portion through which the air is received and an exhausting portion through which the air is exhausted. The cross-sectional area of the receiving decreases toward the exhausting portion, and the cross-sectional area of the exhausting portion decreases toward the receiving portion. (end of abstract) Agent: Volentine Francos, & Whitt PLLC - Reston, VA, US Inventors: Jung-Sung Hwang, Chang-Min Cho, Jae-Hyun Yang, Sang-Mun Chon, Jae-Bong Kim USPTO Applicaton #: 20060003684 - Class: 454186000 (USPTO) Related Patent Categories: Ventilation, Hollow Partition, Having Blower The Patent Description & Claims data below is from USPTO Patent Application 20060003684. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a clean room such as that in which semiconductor devices and liquid crystal displays (LCD) are manufactured. More particularly, the present invention relates to the grating that forms a floor of a clean room system. [0003] 2. Description of the Related Art [0004] Semiconductor devices and liquid crystal displays (LCD) must be manufactured under very precise processing conditions. Therefore, they are fabricated in extremely clean environments unlike many common products of manufacture. In this respect, several semiconductor processing apparatuses are typically provided in separate clean rooms in which the environments are maintained so as to be extremely clean. [0005] In a clean room, technicians work in special dustproof clothes in order to minimize the production of foreign substances such as dust. Also, the upper portion of the clean room is maintained at a pressure slightly higher than the pressure prevailing at the bottom of the clean room such that air (clean air) flows downwardly in the clean room. Grates (panels having holes) provide the floor of the clean room such that the air is discharged through the floor. Therefore, contaminants entrained by the air in the clean room are directed toward the floor of the clean room and are discharged to the outside through the holes of the grating. [0006] However, unlike micro-particles, molecular contaminants in the air of the clean room, referred to as nanoparticles, and airborne molecular contamination (AMC) are not easily removed. In fact, the differential pressure and velocity of the airflow required in the clean room for the nanoparticles and the AMC to be removed must be at least 18% higher than that under which micro-particles are removed. Needless to say, the operating costs of running the air conditioning system of the clean room system to provide such a high differential pressure and airflow velocity are very high. Also, a conventional clean room system that is capable of producing the differential pressure and airflow velocity required for the removal nanoparticles and AMC is very expensive to manufacture. [0007] Also, as illustrated in FIG. 1, eddies are generated when the air passes vertically through the holes in the grating. The eddies are mainly generated at edges of the grates that define the entrances and exits of the holes, as shown with dotted lines. [0008] To conform the effects of these eddies, particles (30,000 to 35,000 counter/cf) were produced at a height of 0.2 m above the conventional grating in a clean room. FIG. 2 illustrates the results of counting the numbers of the particles (30,000 to 35,000 counter/cf) at respective heights in the clean room. As is clear from the results shown in FIG. 2, the particles were distributed to a height of 70 cm due to the eddies. [0009] That is, the eddies generated around the holes of the grating prevent the air from being rapidly exhausted and cause contaminants (in particular, the nanoparticles and the AMC) to reach a height of up to 70 cm from the grating (the floor). As a result, the air is contaminated at the level at which the processes in the clean room are carried out. SUMMARY OF THE INVENTION [0010] An object of the present invention to provide a grate that facilitates a smooth and/or rapid discharging of air from a clean room. [0011] Likewise, another object of the present invention is to provide a clean room system in which air can be discharged smoothly and/or rapidly from the clean room thereof, and which system does not require an expensive air conditioning system. [0012] It is another object of the present invention to provide a grate capable of minimizing eddies in air traveling therethrough to prevent contaminants from being blown upwardly. [0013] According to one aspect of the present invention, a grate used flooring in a clean room comprises a base plate having a plurality of holes that act as nozzles through which the air in the clean room is discharged. [0014] According to another aspect of the present invention, a clean room system comprises a clean room, an air supplying portion including a fan and/or a filter in the ceiling of the clean room to supply clean air into the clean room, and an exhausting portion including grating disposed in the floor of the clean room, the grating defining a plurality of holes through which the air inside the clean room is discharged, and the cross-sectional area of each hole first decreasing and then increasing in a direction from the top (one side) to the bottom (other side) of the grating. [0015] Each of the holes has a receiving portion through which the air is received and an exhausting portion through which the air is exhausted. The cross-sectional area of the receiving portion decreases in a direction toward the exhausting portion. The cross-sectional area of the exhausting portion decreases in a direction toward the receiving portion. [0016] The surfaces that define the receiving portion and the exhausting portion of each hole are frusto-conical or curved. Also, the cross-sectional shape of the holes may be circular or elongate. Still further, each hole may also have a middle portion extending a finite distance between the receiving portion and the exhausting portion. The middle portion has a uniform cross-sectional area. [0017] The grate or grating may also comprise a tile of polyvinyl chloride at the top thereof. BRIEF DESCRIPTION OF THE DRAWINGS [0018] The present invention will now be described in further detail with reference to the accompanying drawings. In the drawings: [0019] FIG. 1 is a sectional view of a conventional grate forming the floor of a clean room; [0020] FIG. 2 is a graph illustrating the distribution of certain particles throughout the height of a clean room whose floor is formed by conventional grating; [0021] FIG. 3 schematic diagram of a clean room system according to the present invention; Continue reading... Full patent description for Grating and clean room system comprising the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Grating and clean room system comprising the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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