Abstract:
A static electricity removal apparatus capable of raising an alternating rate at which ions are generated according to the speed of an object requiring static electricity removal using a high-frequency high voltage AC voltage includes: at least one discharge electrode assembly having a plurality of needle-shaped electrodes aligned with each other, each needle-shaped electrode receiving the high-frequency high voltage AC voltage and generating ions using a corona discharge; a ground electrode for facilitating ion generation by the plurality of needle-shaped electrodes; a high-frequency high voltage generation unit connected to the at least one discharge electrode assembly, the voltage generation unit generating the high-frequency high voltage AC voltage outputted to the plurality of needle-shaped electrodes; and an ion blower adapted to blow ions from the plurality of needle-shaped electrodes to the object requiring static electricity removal.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus for removing static electricity using a high-frequency high voltage alternating current (AC) voltage, and more particularly to a static electricity removal apparatus which is capable of generating ions at an alternating rate according to a moving speed of an object requiring static electricity removal using the high-frequency high voltage AC voltage, thereby enhancing the static electricity removal efficiency. 
     2. Description of the Related Art 
     Generally, in a capacitor fabrication process, a high insulation film (for example, a polypropylene film or the like) is subjected to coating with a high dielectric material while being fed at a high speed using a roller. During this process, when friction and separation occur between the film and the roller guiding the film, a high-level level electrostatic voltage (a maximum of 20,000V) may be generated, resulting in a reduction in work efficiency. For this reason, an apparatus for removing static electricity has been used. 
     The conventional static electricity removal apparatus may, for example, be an ionizer using a commercial AC voltage or a direct current (DC) pulse voltage. However, where the insulation film is treated at a high speed, even after the ionizer has removed the static electricity, a residual electrostatic voltage of a maximum of 7,000V may still remain. Thus, the static electricity removal efficiency of the conventional static electricity removal apparatus is low. 
     To enhance the static electricity removal efficiency, it is necessary to remove the static electricity in accordance with a moving speed of the object requiring static electricity removal. However, ions are generated at a low alternating rate in the conventional static electricity removal apparatus because it uses the commercial AC voltage or the DC pulse voltage, resulting in an inadequate removal of static electricity. 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a static electricity removal apparatus suitable for charged object moving at a high speed, which is capable of raising an alternating rate at which ions are generated in accordance with the speed of the charged object using a high-frequency high voltage AC voltage, resulting in an increased static electricity removal efficiency. 
     In accordance with the present invention, the above and other objects can be accomplished by the provision of a static electricity removal apparatus comprising at least one discharge electrode assembly including a plurality of needle-shaped electrodes aligned with each other, the plurality of needle-shaped electrodes receiving a high-frequency high AC voltage and generating ions using a corona discharge; a ground electrode spaced apart from the discharge electrode assembly by a certain interval, the ground electrode facilitating ion generation by the plurality of needle-shaped electrodes; a high-frequency high voltage generation unit directly connected to the discharge electrode assembly, the voltage generation unit generating the high-frequency high voltage AC voltage outputted to the plurality of needle-shaped electrodes; and an ion blower adapted to blow ions from the discharge electrodes to an object requiring static electricity removal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a cross sectional view of a static electricity removal apparatus using a high-frequency high AC voltage in accordance with an embodiment of the present invention; 
     FIG. 2 is a cross sectional view of a static electricity removal apparatus using a high-frequency high AC voltage in accordance with another embodiment of the present invention; 
     FIGS. 3 a  and  3   b  are side and plan views of discharge electrode assemblies of the static electricity removal apparatus of FIG. 1; 
     FIGS. 4 a  and  4   b  are side and plan views of a discharge electrode assembly of the static electricity removal apparatus of FIG. 2; 
     FIG. 5 is a block diagram showing the construction of a high-frequency high voltage generation unit of the static electricity removal apparatus of FIG. 1 or FIG. 2 according to an embodiment of the present invention; 
     FIGS. 6 a  and  6   b  are side views of a needle-shaped electrode of the static electricity removal apparatus of FIG. 1 or FIG. 2 and a distribution, around the discharge needle, of lines of electric force; 
     FIG. 7 shows a detailed pulse width modulation (PWM) circuit in the high-frequency and voltage generation unit of FIG. 5 according to an embodiment of the present invention; and 
     FIG. 8 shows a detailed ion balance circuit in the high-frequency AC voltage generation unit of FIG. 5 according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     The present invention provides a static electricity removal apparatus using a high-frequency high voltage AC voltage, in which a high-frequency high voltage AC voltage of a frequency of 17 KHz and a maximum voltage of 7000 Volts is generated and then applied to at least one discharge electrode assembly. Hereinafter, a description will be given of the static electricity removal apparatus on the basis of two embodiments, air-blowing and bar types. 
     FIG. 1 is a cross sectional view of a static electricity apparatus of an air-blowing type in accordance with a preferred embodiment of the present invention. 
     As shown in this drawing, the static electricity removal apparatus  10  according to the present invention comprises a fan  11 , first and second discharge electrode assemblies  12   a  and  12   b . The removal apparatus  10  further comprises first and second high-frequency high voltage generation units  13   a  and  13   b  for applying a high-frequency high voltage to the discharge electrode assemblies  12   a  and  12   b . The fan  11  is arranged behind the first and second discharge electrode assemblies  12   a  and  12   b . Each of the discharge electrode assemblies  12   a  and  12   b  has a plurality of needle-shaped electrodes that are aligned with each other. Further, the discharge electrode assemblies  12   a  and  12   b  are respectively placed in upper and lower parts of the removal apparatus  10  to be opposed to each other. 
     The first and second high-frequency high voltage generation units  13   a  and  13   b  which are an important feature of the present invention act to generate a high-frequency high voltage and apply the generated high-frequency high voltage to each of the needle-shaped electrodes of each of the discharge electrode assemblies  12   a  and  12   b  such that a corona discharge occurs around each of the needle-shaped electrodes to generate ions. There is an advantage in that ions are generated at a high alternating rate in the above manner due to the voltage of a high frequency. Finally, the generated ions are moved to charged objects  14  by the fan  11  arranged behind the first and second discharge electrode assemblies  12   a  and  12   b , thereby effectively removing static electricity on the charged objects  14  even while the charged objects  14  move at high speeds. 
     FIG. 2 is a cross sectional view of a static electricity removal apparatus of a bar type which is capable of performing a static electricity removal operation using pressurized air instead of a fan in order to reduce its size in accordance with another preferred embodiment of the present invention. As shown in this drawing, the bar type removal apparatus  20  comprises an air chamber defined in such a way as to communicate with an air inlet defined on a lower surface thereof. The bar type removal apparatus  20  is configured to supply air to the air chamber through the air inlet until air pressure within the air chamber becomes relatively high and to move ions to a charged objects  23  using the force of the air pressure which has become relatively high. 
     The bar type static electricity removal apparatus  20  further comprises a discharge electrode assembly  21  placed between the air inlet and an ion outlet, which includes a plurality of needle-shaped electrodes aligned with each other and spaced at regular intervals, and a high-frequency high voltage generation unit  22  for applying a high-frequency high voltage to each of the needle-shaped electrodes of the discharge electrode assembly  21 . 
     The high-frequency high voltage generation unit  22  generates a high-frequency high AC voltage of a frequency of 17 KHz and a maximum voltage of 7000 Volts according to the present invention. Then, the voltage generation unit  22  applies the generated high-frequency high AC voltage to each of the needle-shaped electrodes of the discharge electrode assembly  21  such that a corona discharge occur using the applied AC voltage to generate ions, thereby achieving a high alternating rate of ion generation. 
     As shown in FIGS. 3 a  and  3   b , each of the first and second discharge assemblies  12   a  and  12   b  of the air-blowing type static electricity removal apparatus  10  has 8 needle-shaped electrodes  31  aligned with each other at intervals of, preferably, about 25 mm. The first and second discharge assemblies  12   a  and  12   b  may preferably be positioned in such a manner as to be opposed to each other such that ions generated from each of the needle-shaped electrodes  31  are effectively moved to the charged objects  14  by air flow from the fan  11  to the charged objects  14 . 
     As shown in FIGS. 4 a  and  4   b , the discharge electrode assembly  21  of the bar type static electricity removal apparatus  20  has  30  needle-shaped electrodes  31  aligned with each other at intervals of about 25 mm. 
     The needle-shaped electrodes  31  are spaced apart from each other at intervals of preferably about 20˜30 mm, most preferably about 25 mm, for the purpose of achieving the maximum ion generation amount and preventing a spark discharge therebetween. 
     Each of the needle-shaped electrodes  31  included in each of the discharge electrode assemblies  12   a ,  12   b  and  21  has a length of 13 mm and a diameter of 1.53 mm, as shown in FIG. 6 a , and is made of tungsten (99.95%). In order to optimize an ion generation amount and ion generation range, it is preferable that the end of each of the needle-shaped electrodes  31  has a radius of curvature of 2 mm. 
     If the high-frequency high voltage AC voltage from the high-frequency high voltage generation unit  13   a ,  13   b  or  22  is applied to the corresponding needle-shaped electrodes  31  having the above described shape, a distribution of lines of electric force is formed in the neighborhood of each of the needle-shaped electrodes  31 , as shown in FIG. 6 b.    
     FIG. 5 is a block diagram showing the construction of the high-frequency high voltage generation unit  13   a ,  13   b  or  22  for applying the high-frequency high voltage AC voltage to the corresponding discharge electrode assembly  12   a ,  12   b  or  21 . 
     The high-frequency high voltage generation unit provided in the present invention includes a frequency generator  51  for generating a high frequency signal having a predetermined frequency (for example, 17 KHz) a pulse width modulation circuit  52  for generating a pulse signal on the basis of the high frequency signal from the frequency generator  51 , a high voltage generation circuit  53  for boosting the voltage level of the pulse signal from the pulse width modulation circuit  52  to a predetermined voltage level, generating a high-frequency high voltage AC voltage signal and outputting the generated high-frequency high voltage AC voltage signal, and an ion balance circuit  54  for inputting the high-frequency high voltage AC voltage signal fed back from the high voltage generation circuit  53  and providing the pulse width modulation circuit  52  with a compensation value according to an output variation of the high-frequency high voltage AC voltage signal outputted from the high voltage generation circuit  53 . 
     When inputting a compensation signal, or the compensation value, from the ion balance circuit  54 , the pulse width modulation circuit  52  adjusts a pulse width of its output pulse signal on the basis of a high frequency signal from the frequency generator  51  in consideration of the compensation signal. 
     FIG. 7 is a detailed circuit diagram illustrating an embodiment of the pulse width modulation circuit  52  and high voltage generation circuit  53 . First, headers  1  and  2  J 3  are simultaneously provided with high frequency signals from the frequency generator  51 . Then, the headers  1  and  2  J 3  respectively apply the provided high frequency signals to upper and lower PWM ICs U 3  as a clock signal of a certain period through associated photo couplers U 1 . At this time, the upper and lower PWM ICs U 3  are respectively provided with (+) pulse signal and (−) pulse signal from the headers  1  and  2 . Then, the upper and lower PWM ICs U 3  transfer the provided (+) pulse signal and (−) pulse signal to a transformer T 1 , respectively. If the (+) pulse signal and (−) pulse signal is applied to the transformer T 1 , then the transformer T 1  outputs a high-frequency high voltage AC voltage through its secondary coil. The high-frequency high voltage AC voltage signal generated in this manner is applied to each of the needle-shaped electrodes of each of the discharge electrode assemblies  12   a  and  12   b  or of the discharge electrode assembly  21 , so that ions are generated at a high alternation rate as shown in FIG.  6 . 
     FIG. 8 is a detailed circuit diagram illustrating an embodiment of the ion balance circuit  54 . The ion balance circuit  54  inputs the high-frequency high voltage AC voltage signal through its input terminal J 7  connected to an output terminal of the high voltage generation circuit  53 . Then, the high-frequency high AC voltage signal inputted to the ion balance circuit  54  is applied to an operational amplifier U 4 D and then amplified by it. Subsequently, a (+) input terminal of an operational amplifier U 4 B inputs the amplified AC voltage signal, and a (−) input terminal thereof inputs a reference voltage. The AC voltage signal inputted to the amplifier U 4 B is integrated by an integration circuit including the operational amplifier U 4 B and passive elements R 29 , R 30 , C 27 , C 30  and so forth. The integrated AC voltage signal is then applied to the pulse width modulation circuit  52  to be used as a compensation signal. 
     It should be noted that the circuit diagrams of FIGS. 7 and 8 have been taken as examples of circuit configurations for generating the high-frequency high voltage AC voltage signal. However, the present invention is not limited thereto. 
     As described above, a high-frequency high voltage AC voltage signal generated by the high-frequency high voltage generation unit is applied to the discharge electrode assembly such that a corona discharge occurs around each of the needle-shaped electrodes of the discharge electrode assembly to generate ions. The ions generated in this manner are moved to the charged objects by the wind (a maximum of 0.87 m 3 /min) from the fan or by air pressure (a maximum of 5 kg/cm 3 ) generated by air injection from the air inlet, and bound to ions causing static electricity on a surface of each of the charged objects, thereby removing the static electricity. 
     The AC voltage applied to the discharge electrode assembly has a high frequency of 17 KHz. Accordingly, an alternating rate at which the ions are generated becomes high. As a result, the static electricity on the charged objects can be rapidly removed even though each of the charged objects moves at a high speed (a maximum of 50 m/sec). 
     As apparent from the above description, the present invention provides a static electricity removal apparatus which is capable of raising an alternating rate of ion generation by applying a voltage of a high frequency to a discharge electrode, thereby effectively removing static electricity occurring on charged objects moving at high speeds. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.