Abstract:
A plane type electric precipitator includes an electrode plate of plane shape, made of electricity-conducting material; a collecting plate, parallel to the electrode plate and made of electricity-conducting material; a plurality of electrode units, placed on the electrode plate and having tips; wherein direct electric voltage is applied between the electrode plate and the collecting plate, so that air passing through is exposed to high electric fields close to the tips of the electrode units, ionizing suspended particles and trapping ionized particles at the collecting plate, so that an air-cleaning effect results.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a planar electric precipitator, particularly to a planar electric precipitator which is easy to manufacture and of flat shape to be suitable for industrial and home use. 
   2. Description of Related Art 
   In conventional art, particles suspended in the air are removed by letting an air flow pass through a channel in which a pointed electrode is placed. Direct voltage between the electrode and a collecting plate causes the particles contained in the air flow to be ionized and drawn towards the collecting plate and thus to be removed from the air. 
   Electrostatic air cleaning apparatuses as just described work effectively and therefore are widely used to clean air in closed rooms. However, conventional electrostatic air cleaning apparatuses generally have large volumes and need to be placed on floors, which consumes valuable space and is inconvenient. 
   The main reason for a large volume of a conventional electrostatic air cleaning apparatus lies in a large thickness due to required distances between electrodes and collecting plates and the need to install several layers of electrodes and collecting plates for better effectivity. 
   Another shortcoming of conventional electrostatic air cleaning apparatuses is the difficulty during manufacture of precisely controlling distances and mutual orientations between electrodes and collecting plates, so as to prevent smoke from entering air channels and preserving ionizing capability. 
   The present inventor has been aware that conventional art does not solve the problems of large volume, difficulty of manufacturing and cost reduction. U.S. patent publication no. US005925170A “Electric dust-collection unit and air-cleaning apparatus” discloses an electrostatic air cleaning apparatus having a plurality of electrodes, each made of a wire with a needle tip, oriented parallel to each other, which results in a large thickness and hence a large volume of the apparatus. Furthermore, the electrodes, being separable from a base, during manufacture need to be placed precisely one by one, which is difficult and expensive. 
   U.S. patent publication no. US006524369B1 “Multi-stage particular matter collector” discloses an electrostatic air cleaning apparatus having a plurality of electrodes, each being a metal plate with sharp edges, vertically placed on a horizontal collector plate. Therefore, the apparatus has a height that is hard to reduce, resulting in a large volume. 
   U.S. patent publication No. US005322550A “Electrical dust collector” discloses an electrostatic air cleaning apparatus having a plurality of electrodes which are made by punching and bending a metal plate and a plurality of collecting plates made by punching and bending a metal plate, too, and interleaving with the plurality of electrodes. This apparatus has a somewhat reduced thickness, but a satisfactorily small volume is not achieved. Furthermore, manufacturing by punching and bending into precise angles is difficult due to the elasticity of metal plates, so that precision and hence effectivity of the apparatus are not sufficiently high. 
   U.S. patent publication No. US005492557A “Filter device for air purification” discloses an electrostatic air cleaning apparatus having a plurality of electrodes which are made from a metal plate by punching a plurality of holes with pointed flaps reaching inside and being bent away at predetermined angles to form electrodes. Thereby the apparatus is almost flat, but a minimum thickness is still required by orienting a collecting plate perpendicular to the electrodes. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a plane type electric precipitator having a flat shape. 
   Another object of the present invention is to provide a plane type electric precipitator which is easy to manufacture and maintains precision. 
   The present invention mainly comprises a discharging plate, a collecting plate, oriented parallel thereto, a plurality of electrode units, placed on the electrode plate at equal mutual distances and made by punching or laser cutting. Each discharging unit has an electrode opening and at least two electrode tips, placed therein at rotationally symmetric positions. The collecting plate has a plurality of collectors at positions that correspond to positions of the electrode units on the electrode plate. Each collecting unit has a collector surface, shaped like a depression and surrounded by several air-holes. Direct electric voltage is applied between the electrode plate and the collecting plate, so that air passing through is exposed to high electric fields close to the tips of the discharging units, ionizing suspended particles and trapping ionized particles at the collecting plate, so that an air-cleaning effect results. A cover plate covers the electrode plate, preventing accidental touching thereof and providing a decorative look. 
   Due to a flat shape, the present invention is placeable on walls ceilings or floors, without consuming valuable space. Producing the electrode plate and the collecting plate by punching or laser cutting allows for easy manufacturing and precise controlling of dimensions and positions of the electrode units and collecting units, optimizing air-cleaning effectivity of the present invention. 
   The present invention can be more fully understood by reference to the following description and accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of the plane type electric precipitator of the present invention in the first embodiment. 
       FIG. 2  is a perspective view of the plane type electric precipitator of the present invention in the first embodiment. 
       FIG. 3  is a side view of the plane type electric precipitator of the present invention in the first embodiment. 
       FIG. 4  is a top view of the electrode plate of the present invention in the first embodiment. 
       FIG. 5  is a top view of the collecting plate of the present invention in the first embodiment. 
       FIG. 6  is an enlarged cross-sectional view of the electrode plate and the collecting plate of the present invention in the first embodiment. 
       FIG. 7  is an enlarged perspective view of the electrode unit of the present invention in the second embodiment. 
       FIG. 8  is an enlarged cross-sectional view of the electrode plate and the collecting plate of the present invention in the second embodiment. 
       FIG. 9  is an enlarged cross-sectional view of the electrode plate and the collecting plate of the present invention in the third embodiment. 
       FIG. 10  is a partial cross-sectional view of the present invention in the fourth embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As shown in  FIG. 1 , the plane type electric precipitator of the present invention comprises: a electrode plate  10 ; a plurality of electrode units  20 ; a collecting plate  30 ; a plurality of collecting units  40 ; a frame  50 ; a cover plate  60 ; and a plurality of fixing elements  70 . The electrode plate  10  is made of electricity-conducting metal and carries the electrode units  20 . The electrode units  20  serve to ionize particles suspended in air. The collecting plate  30  is oriented parallel to the electrode plate  10 . Direct voltage is applied between the electrode plate  10  and the collecting plate  30 , so that particles flowing by in between are ionized. The-collecting units  40  are mounted on the collecting plate  30  in positions corresponding to the electrode units  20  to increase effectiveness. The frame  50  carries both the electrode plate  10  and the collecting plate  30 . The cover plate  60  is mounted on the frame  50 , covering the electrode plate  10 , protecting against accidental touching thereof, and is preferably made as a decorative object. The fixing elements  70  fix a relative position of the electrode plate  10  against the collecting plate  30 . 
   Referring to  FIGS. 1 and 4 , the electrode plate  10  is made of electricity-conducting metal and carries the electrode units  20 . As shown in  FIG. 4 , each of the electrode units  20  has an electrode opening  21 . Each electrode opening  21  has an inner periphery in which a plurality of electrodes  22  are placed in rotationally symmetric positions. Neighboring electrode units  20  have equal distances and are equally oriented. 
   In a first embodiment of the present invention, the electrodes  22  are oriented parallel to the electrode plate  10  and are made by punching or laser cutting, delineating circumferences of the electrode openings  21  and the electrodes  22 , so that manufacturing is simple and precision is easily controlled. For the electrode units  20  and the electrode plate  10 , readily available parts are used, so that no complicated assembly process is required and cost is reduced. 
   Referring to  FIGS. 1 ,  2  and  6 , the collecting plate  30  is mounted below the electrode plate  10 ., with the collecting units  40  and the electrode units  20  facing each other. As shown in  FIGS. 5 and 6 , each of the collecting units  40  has a collector surface  41 , which is formed as a round depression surrounded by several air holes  42 . The collectors surfaces  41  are made by punching, and the air holes  42  are made by punching or laser cutting, resulting in a simple manufacturing process. 
   Referring again to  FIG. 6 , the electrode units  20  on the electrode plate  10  and the collecting units  40  on the collector plate  30  are placed at positions corresponding to each other. The electrode openings  21  of the electrode units  20  allow air to pass through. Furthermore, since the holes  21  and the collectors surfaces  41  are aligned to each other, air that has passed through one of the electrode openings  21  is directed towards one of the collectors surfaces  41  at a corresponding position. Air hits the collectors surfaces  41 , which are formed like circular depressions, before escaping through the respective surrounding air holes  42 . Therefore, the collector surfaces  41  cause stagnation flow downstream of said electrode openings  21  and air stays close to the collector plate  30  for an extended period, enhancing the effectiveness of particle collection. Furthermore, due to the shape of the collectors surfaces  41  large quantities of particles are readily collected therein. 
   Direct voltage is applied between the electrode plate  10  and the collector plate  30 , so that particles in the air close to tips of the electrodes tips  22  are exposed to a high electric field and ionized. Ionized particles are, due to the electric field between the electrode plate  10  and the collector plate  30 , drawn towards the collecting plate  30  and trapped there. 
   For fixing the relative position of the electrode plate  10  against the collecting plate  30  and simplifying assembly, the plurality of fixing elements  70  pass through both the electrode plate  10  and the collecting plate  30 . As shown in  FIGS. 1 and 6 , each of the fixing elements  70  is shaped like a cylinder with a middle section of a relatively large diameter and two opposite end sections  71  of relatively small diameters. The end sections fit tightly into fixing holes  11  on the electrode plate  10  and fixing holes  31  on the collecting plate  30 . The fixing holes  11  and the fixing holes  31  are aligned to each other and allow to place the electrode plate  10  and the collecting plate  30  precisely above each other. Furthermore, since the middle sections of the fixing elements  70  have equal lengths, the electrode plate  10  and the collecting plate  30  are kept parallel. 
   Thereby, the electrodes tips  22  of the electrode units  20  and the collectors surfaces  41  of the collecting units  40  point precisely towards each other and have equal distances, so that ionization as well as air flow work effectively. 
   Aligning of the electrode units  20  and the collecting units  40  is attainable by various means, which in the scope of the present invention are not restricted to the embodiment described here. 
   Referring to  FIGS. 1-3 , the electrode plate  10  and the collecting plate  30  are mounted on the frame  50  using at least four bolts  80  and nuts  81  at four corners thereof. The frame  50  has a central opening  51  with four corners which is slightly smaller than the electrode plate  10  and the collecting plate  30 , allowing air to pass through. Threaded holes at the four corners of the central opening  51  accommodate the bolts  80 , allowing to fasten the electrode plate  10  and the collecting plate  30  on the frame  50 . The frame  50 , besides supporting the electrode plate  10  and the collecting plate  30 , serves to accommodate electronic and controlling components. 
   As further shown in  FIGS. 1-3 , the cover plate  60  covers the central opening  51  of the frame  50  on an outer side thereof. The cover plate  60  has ventilation openings  61  and four threaded holes  62  at four corners, allowing to fasten the cover plate  60  on the frame  50  using screws  90  and nuts  91 . 
   The cover plate  60  serves to prevent accidental contact of a user or of objects with the electrode plate  10 . Furthermore, the cover plate  60  is preferably provided with a decorative design for good looks. 
   In the embodiment described here, the electrode plate  10 , the collecting plate  30 , the frame  50  and the cover plate  60  all have rectangular shapes. Other suitable geometric shapes, like square, circular or triangular shapes are possible within the scope of the present invention. Preferably, the ventilation openings  61 , the electrode unit  20  on the electrode plate  10  and the collecting unit  40  on the collecting plate  30  have equal distances to ensure a uniform air flow for every place of installation of the present invention. 
   A main characteristic of the present invention lies in the flat shape of the electrode plate  10  and the nearly flat shape of the collecting plate  30 , from which the collectors surfaces  41  protrude by small distances only. Thus the electrode plate  10  and the collecting plate  30  combined have only a small thickness, allowing to place the electric precipitator of the present invention at a wall, on a ceiling or on a floor or as an integral part of an air ventilation system, so that no valuable space is wasted. 
   If hung on a wall, with the cover plate  60  carrying a suitable design, the electric precipitator of the present invention resembles a picture. Suitable designs for placing the present invention at a ceiling or a floor, resembling ceiling elements or wooden floor plates, are also possible. 
   As compared to conventional art, a further advantage of the present invention lies in easy manufacturing of the electrode plate  10  and the collecting plate  30  by punching or laser cutting, allowing to work the electrode units  20  and the collecting units  40  in a simple and precise way with well-defined dimensions and shapes. Aligning the electrode units  20  and the collecting units  40  by the fixing elements  70  is easy and quickly performed, reducing manufacturing cost. 
   Referring to  FIGS. 7-8 , the present invention in a second embodiment has electrode units  20 A with electrodes tips  22 A that are bent towards the collecting plate  30  at defined angles, having tips that are closer to the collecting plate  30  than the distance between the electrode plate  10  to the collecting plate  30 . 
   Referring to  FIG. 9 , the present invention in a third embodiment has a collecting plate  30 A which is a single plane sheet without a collecting unit, with electric discharge occuring between the electrodes  22  of the electrode units  20  and the collecting plate  30 A. 
   Referring to  FIG. 10 , the present invention in a fourth embodiment has several ventilation holes  54  on a rear side of the frame  50 , with a ventilator  55  increasing air flow and hence air cleaning effectivity. 
   While the invention has been described with reference to preferred embodiments thereof, it is to be understood that modifications or variations maybe easily made without departing from the spirit of this invention which is defined by the appended claims.