Dust collector for collecting fine dust in air

Information

  • Patent Grant
  • 6821320
  • Patent Number
    6,821,320
  • Date Filed
    Monday, November 18, 2002
    22 years ago
  • Date Issued
    Tuesday, November 23, 2004
    20 years ago
Abstract
A dust collector for collecting fine dust in air and for cleaning the air is provided. A first friction disk is produced from a first substance. A second friction disk is produced from a second substance that is chargeable triboelectrically in a polarity different from a polarity of the first substance. The first and second friction disks frictionally contact one another. The second friction disk moves relative to the first friction disk, to generate electrostatic charge and thereby attract fine dust.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a dust collector for collecting fine dust in air. More particularly, the present invention relates to a dust collector for collecting fine dust in air, which is used with an air supply assembly for supplying the air through a duct, and can efficiently collect dust or fine particles to clean the




2. Description Related to the Prior Art




There are various types of dust collectors, of which an example is disclosed in U.S. Pat. No. 6,193,788 (corresponding to JP-A 10-249235). A plurality of needle electrodes charges floating fine particles in air by causing corona discharge in the periphery of their needle ends. A plurality of cell-shaped collecting electrodes attract and collect the particles electrostatically after charging by the needle electrodes.




JP-A 10-323580 discloses a frictional electrification device in which objects are charged at an amount required for classifying target crushed trash including plastic material. The frictional electrification device includes an outer container, and an inner container disposed in the outer container in a rotatable and vibratile manner. An agitation blade is disposed in the inner container, for rotating in a direction backward to that of the inner container. When the inner container is supplied with the target crushed trash, the agitation blade mover the target crushed trash toward the trash exit port successively. Electric charge is generated by frictional contact of the inner container with the agitation blade in rotation and vibration, and also by frictional contact between pieces of the target crushed trash. According to a triboelectric series including related substances, the target crushed trash with particular characteristics is charged positively or negatively, and then is exited through a trash exit port. Note that the triboelectric series is a train of substances obtained in such a manner that, when two substances are combined as a pair and frictionally contacted by one another, one is charged positively, the remainder being charged negatively, and that numerous substances are arranged according to the electrically negative and positive characteristics after experiments.




However, the dust collector of the first of the two documents has shortcomings. Because a direct-current power source of high voltage is required, manual handling of the dust collector is dangerous to users. Also, a manufacturing cost is considerably high. Furthermore, the frictional electrification device of the second of the two documents has problems. Electric charge is generated nearly in entirety of the inside of the inner container by the charging operation. For the periodical maintenance after repeated use, large regions in the frictional electrification device should be cleaned, including an inner surface of the inner container and a surface of the agitation blade. However, no disassembly of the outer container of the inner container is disclosed in the document. To clean and maintain the frictional electrification device requires much time and laborious operation.




SUMMARY OF THE INVENTION




In view of the foregoing problems, an object of the present invention is to provide a dust collector for collecting fine dust in air, capable of collecting floating fine particles safely and also at a lost cost.




Another object of the present invention is to provide a dust collector for collecting fine dust in air, capable of being cleaned with great ease.




In order to achieve the above and other objects and advantages of this invention, a dust collector for collecting fine dust in air and for cleaning the air is provided. A first friction member is produced from a first substance. A second friction member is produced from a second substance that is chargeable triboelectrically in a polarity different from a polarity of the first substance. A friction driving mechanism moves one of the first and second friction members relative to a remaining one thereof, and frictionally generates electrostatic charge, to attract the fine dust.




In other words, a first friction device is produced from a first substance. A second friction device is produced from a second substance which is in a different position from the first substance in a triboelectric series of substances, for frictionally contacting the first friction device. A moving mechanism moves one of the first and second friction devices relative to a remaining one thereof, to generate electrostatic charge by charging the first and second friction devices, so as to attract the fine dust.




The first substance is polytetrafluoroethylene.




At least one of the first and second substances has a surface resistance of 10


9


Ω or higher.




Furthermore, there is a passage case for flowing through of the air, the first and second friction devices contact one another inside the passage case. A fan sends the air through the passage case.




The first and second friction devices have a plate shape, the first friction device is stationary with the passage case. The moving mechanism moves the second friction device.




The first and second substances have such characteristics as to be charged respectively in negative and positive states when frictionally contacted on one another.




The fan sends the air from an air intake port of the passage case to an air, exhaust port thereof. Furthermore, a filter is disposed in the air intake, port, for preventing dust from entry therein.




The moving mechanism includes a motor for rotating the second friction device.




The first friction device is secured to a case panel of the passage case.




Furthermore, an access opening is formed in the passage case, and provided with the first friction device secured to an inside thereof. A fastener retains the first friction device in the access opening, the fastener being detached for cleaning or maintaining the first and second friction devices, to allow removal of the first friction device from the access opening.




Furthermore, one case panel in provided with the first friction device secured thereto, retained in the access opening by the fastener, for closing the access opening.




Furthermore, a biasing mechanism presses the second friction device against the first friction device.




The case panel is a lower panel of the passage case disposed on a downside.




In a preferred embodiment, the case panel comprises a lower panel and au upper panel of the passage case disposed on respectively a downside and upside. First and second electrostatic generator units are disposed in respectively the lower and upper panels, each of the first and second electrostatic generator units being constituted by the first and second friction devices.




Furthermore, first and second axial holes are formed through respectively the case panel and the first friction device. The motor is disposed outside the case panel, has an output shaft extending through the first and second axial holes, for rotating the second friction device.




The air is supplied to a thermal bead of a thermal printer by the fan through the passage case, to cool the thermal head.




The second friction device has a disk shape.




The second substance is polypropylene.




In another preferred embodiment, furthermore, a dust eliminating portion rubs away the fine dust stuck on the first or second friction device.




The moving mechanism includes a motor for rotating the second friction device. The dust eliminating portion is a dust eliminating edge portion of the second friction device, extending in a direction away from a rotational center thereof, for rubbing the first friction device in rotation of the second friction device, to eliminate the fine dust stuck on the first or second friction device.




The first and second friction devices are disposed in an upper panel of the passage case disposed on an upside. Furthermore, a dust exit path is formed in a downside of the passage case, for passing down the fine dust from the dust eliminating portion, to exit the fine dust.




Furthermore, a dust containing case is disposed under the dust exit path, for receiving the fine dust to be abandoned.




The passage case includes an intermediate casing frame, has the dust exit path, and in which the first and second friction devices contact one another. An upstream casing frame is connected with the intermediate casing frame on an upstream side, for containing the filter. A downstream casing frame is connected with the intermediate casing frame on a downstream side, for containing the fan.




The first friction device is the intermediate casing frame.




Furthermore, a first shutter openably closes a path of the air extending from the air intake port toward the air exhaust port. A second shutter closes the dust exit path openably. A controller opens and closes the first and second shutters alternately, drives the fan to eject the air from the passage case while the second shutter is closed and the first shutter is open, and drives the moving mechanism to attract the fine dust while the first shutter is closed and the second shutter is open.




The controller measures driving time of driving the moving mechanism, and when the driving time increases to become a predetermined time, stops driving the moving mechanism, and closes the second shutter.




The controller measures elapsed time elapsed after stopping driving the moving mechanism, and when the elapsed time increases to become a predetermined limit time, stops driving the fan, and closes the first shutter.




At a time of powering, the controller closes the first shutter, opens the second shutter, and also drives the moving mechanism to attract the fine dust.




A surface resistance of the intermediate casing frame is higher than a surface resistance of the upstream and downstream casing frames, and is 10


9


Ω or higher.




In a further preferred embodiment, the second friction device has a peripheral edge of which at least one portion extends in a direction away from a rotational center thereof, and constitutes the dust eliminating edge portion.




In another preferred embodiment, the second friction device includes a rotatable plate or disk. At least one opening is formed in the plate or disk, has an inner edge portion including the dust eliminating edge portion.




The at least one opening is plural openings.




In still another preferred embodiment, the second friction device has at least one arm disposed to extend in a direction away from a rotational center thereof, the arm having the dust eliminating edge portion.











BRIEF DESCRIPTION OF THE DRAWINGS




The above objects and advantages of the present invention will become more apparent from the following detailed description when read in connection with the accompanying drawings, in which:





FIG. 1

is a vertical section, illustrating a dust collector of the invention in combination with a thermal head;





FIG. 2

is a vertical section illustrating the dust collector;





FIG. 3

is a perspective illustrating an electrostatic generator unit;





FIG. 4

is an explanatory view illustrating a charged state of the electrostatic generator unit;





FIG. 5

is a graph illustrating a relationship between a potential (V) of charging and surface resistance (Ω) of polypropylene or the second friction disk;





FIG. 6

is an explanatory view illustrating the thermal printer;





FIG. 7

is a vertical section illustrating another preferred dust collector including two electrostatic generator units;





FIG. 8

is a vertical section illustrating a further preferred dust collector in which an electrostatic generator unit is located in the upside;





FIG. 9

is a perspective, partially broken, illustrating the electrostatic generator unit;





FIG. 10

is a block diagram schematically illustrating thermal printer with the electrostatic generator unit;





FIG. 11

is a flow chart illustrating a sequence of the operation of the dust collector;





FIG. 12

is a vertical section illustrating another dust collector in which a fan is disposed near to an air intake port;





FIG. 13

is a perspective, partially broken, illustrating a friction plate according to another preferred embodiment, in which dust eliminating edge portions are formed by forming openings;





FIG. 14

is a perspective, partially broken, illustrating a friction disk according to still another preferred embodiment, which is circular and in which dust eliminating edge portions are formed;





FIG. 15

is a perspective, partially broken, illustrating a friction member according to another preferred embodiment, which is cross-shaped.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) OF THE PRESENT INVENTION




In

FIG. 1

, a dust collector


10


for use with a thermal printer


11


is depicted. The thermal printer


11


includes a thermal head


14


and a lateral panel


12


. The dust collector


10


is fitted in an opening


12




a


formed in the lateral panel


12


, and secured to the thermal printer


11


. A duct


13


is connected with the dust collector


10


, to cool the thermal head


14


by sending cooling air from the dust collector


10


. To keep cooling air free from dust, the dust collector


10


, or air cleaner of dust collecting type is incorporated in a cooling air supply device for the thermal head


14


.




In

FIG. 2

, the dust collector


10


includes a passage case


15


, a filter


16


, a fan


17


and an electrostatic generator unit


18


. In the passage case


15


are formed an air intake port


15




a


and an air exhaust port


15




b


. The passage case


15


has a shape of a rectangular parallelepipedon. The filter


16


is formed from polyurethane foam, and fitted in the air intake port


15




a


. The fan


17


is disposed near to the air exhaust port


15




b


. The electrostatic generator unit


18


is secured to a panel of the passage case


15


between the air intake port


15




a


and the air exhaust port


15




b.






The filter


16


, instead of using the polyurethane foam, may be a HEPA filter (high efficiency particulate air filter) or an ULPA filter (ultra low penetration air filter). The fan


17


includes a propeller or blades


17




a


and a motor


17




b


for rotating the propeller


17




a.






The electrostatic generator unit


18


includes a first friction disk


21


, a second friction disk


22


, a motor


23


and a case panel


24


. The first friction disk


21


as first friction device is formed from polytetrafluoroethylene or Teflon (trade name). The second friction disk


22


as second friction device is formed from polypropylene, and frictionally contacts the first friction disk


21


. The motor


23


as moving mechanism rotates the second friction disk


22


. The case panel


24


or lid panel supports the first friction disk


21


and the motor


23


in a fixed manner. An access opening


15




c


is formed in the passage case


15


, and receives the case panel


24


fitted therein. Four fastening screws


25


as fastener are used to fix the case panel


24


to the access opening


15




c


. When the fastening screws


25


are unfastened, the electrostatic generator unit


18


is removed from the passage case


15


, for a user to clean the first and second friction disks


21


and


22


with great ease by separating the electrostatic generator unit


18


from the passage case


15


.




Axial holes


21




a


and


24




a


are formed in respectively the first friction disk


21


and the case panel


24


. A motor output shaft


26


or transmission shaft of the motor


23


is loosely inserted in the axial holes


21




a


and


24




a


. An engaging key


26




a


projects from a middle portion of the motor output abaft


26


. A key way


22




a


is formed in the second friction disk


22


, becomes engaged with the engaging key


26




a


. When the motor output shaft


26


rotates, the second friction disk


22


also rotates,




In

FIG. 3

, a biasing coil spring


27


as biasing mechanism is positioned at and received by the motor output shaft


26


which projects from an upper surface of the second friction disk


22


. The coil spring


27


presses the second friction disk


22


against the first friction disk


21


. A flange ring


28


or washer is disposed at an upper end of the motor output shaft


26


, contacts the coil spring


27


and pushes the coil spring


27


downwards. A nut


29


is secured to the motor output shaft


26


, and keeps the flange ring


28


in the position. The firmness of fastening the nut


29


can be adjusted to change the force applied by the coil spring


27


between the second friction disk


22


and the first friction disk


21


. Note that four screws


30


fix the first friction disk


21


to the case panel


24


.




When the motor


23


is driven to rotate the motor output shaft


26


, the second friction disk


22


rotates. A lower surface of the second friction disk


22


frictionally contacts and rubs an upper surface of the first friction disk


21


. As the first friction disk


21


is Teflon and the second friction disk


22


is polypropylene, the first friction disk


21


is charged negatively, and the second friction disk


22


is charged positively. This is according to the characteristics of the substances as indicated in the triboelectric series described herein. In

FIG. 4

, positively charged floating fine particles


31


as dust are attracted by the first friction disk


21


. Negatively charged floating fine particles


32


as dust are attracted by the second friction disk


22


. Note that the triboelectric series is a train of substances. When two substances are combined as a pair and frictionally contacted by one another, one is charged positively, the remainder being charged negatively. Various substances are arranged in one series according to the positive and negative states when charged by friction. An effect of charging by frictional contact of two substances in the triboelectric series is lower according to closeness between those in the triboelectric series, and is higher according to a distance between those in the triboelectric series.




The triboelectric series, from the positive side (+) to the negative side (−); Asbestos-Human hair, animal fur Class-Wool-Nylon-Rayon-Lead-Silk-Cotton Hemp-Wood-Human skin-Acetate-Aluminum-Paper-Steel-Copper-Nickel-Rubber-Polypropylene-Polyester-Acrylic material-Polyurethane-Polyethylene-Polyvinyl chloride-KEL-F (trade name of polychloro trifluoro ethylene)-Teflon (trade name).




The dust collector


10


starts operation experimentally. When three minutes lapses after the start, a potential (V) of charging and the surface resistance (Ω) of polypropylene are measured. In

FIG. 5

, a relationship between those two is illustrated. If the surface resistance of the polypropylene is 10


9


Ω or less, the potential is zero. No collection of dust can be effected. It is necessary that at least one of the two substances should have a surface resistance of 10


9


Ω or more for ensuring sufficient potential of charging for the purpose of performance of the dust collection. Note that plural values of the potential were obtained for each one value of the surface resistance. This shows occurrence of deviations in the results of the experiment. In

FIG. 5

, a broken line P indicates an average of the potential values.




In

FIG. 6

, main portions of the thermal printer


11


is depicted. A duct exhaust port


13




a


is included in the duct


13


. A pivot


34


of the thermal head


14


keeps the thermal head


14


rotatable under the duct exhaust port


13




a


. A heat sink assembly


35


of aluminum is secured to a top of the thermal head


14


, and receives cooling air which is supplied through the duct exhaust port


13




a.






A heating element array


36


is incorporated in the thermal head


14


, and positioned opposite to the heat sink assembly


35


. As is well-known in the art, the heating element array


36


includes a great number of heating elements arranged in line perpendicular to the drawing sheet of

FIG. 6. A

platen roller


38


is disposed under the heating element array


36


and opposed thereto. Color thermosensitive recording material


40


is squeezed between the platen roller


38


and the heating element array


36


. A full-color image is recorded to the recording material


40


while the recording material


40


is fed.




The recording material


40


includes a support, plural coloring layers and a transparent protective layer. The support is formed from paper or the like. The coloring layers are overlaid on one another, and develop colors of respectively cyan, magenta and yellow, Among the coloring layers, the cyan coloring layer has the lowest heat sensitivity, and develops the cyan color if relatively high heat energy is applied to it. The magenta coloring layer has a medium heat sensitivity. The yellow coloring layer has the highest heat sensitivity, and develops the yellow color if relatively low-heat energy to applied to it.




The yellow and magenta coloring layers have characteristics of fixability in response to electromagnetic rays. Before the magenta recording, the yellow coloring layer is fixed to prevent further development of yellow by destroying coloring ability of a remaining yellow coloring component. Before the cyan recording, the magenta coloring layer is fixed to prevent further development of magenta by destroying coloring ability of a remaining magenta coloring component. To be precise, the magenta coloring layer has the maximum absorption wavelength of approximately 365 nm, so its coloring ability is destroyed when ultraviolet rays peaking at this wavelength is applied to it. The yellow coloring layer has the maximum absorption wavelength of approximately 420 nm, so its coloring ability is destroyed when visible violet rays peaking at this wavelength is applied to it.




A material roll


40




a


is constituted by the recording material


40


in a continuous form wound in a roll form. A supply roller set


42


unwinds the recording material


40


from the material roll


40




a


. A feeding path


44


in a straight form is supplied with the recording material


40


by the supply roller set


42


. A feeder roller set


45


nips the recording material


40


, and sends the recording material


40


to a printing station where the thermal head


14


and the platen roller


38


operate.




A feeder roller set


46


is disposed in the vicinity of the platen roller


38


. There are a yellow photo fixer


47


and a magenta photo fixer


48


for electromagnetically fixing the recording material


40


after the thermal recording. An ejection roller set


49


is also disposed for feeding the recording material


40


toward a receptacle tray (not shown) after the fixation.




The yellow photo fixer


47


includes an ultraviolet lamp


47




a


and a reflector


47




b


. The ultraviolet lamp


47




a


has a tubular shape, and emits near ultraviolet rays of which a peak of emission is at a wavelength of approximately 420 nm. The magenta photo fixer


48


includes an ultraviolet lamp


48




a


and a reflector


48




b


. The ultraviolet lamp


48




a


has a tubular shape, and emits near ultraviolet rays of which a peak of emission is at a wavelength of approximately 365 nm.




A feeder motor


50


drives the feeder roller sets


45


and


46


and the ejection roller set


49


to transport the recording material


40


in an advancing direction at and a returning direction β. The recording material


40


is fed back and forth along the feeding path


44


by the feeder roller sets


45


and


46


and the ejection roller set


49


. The thermal head


14


records yellow, magenta and cyan images to the recording material


40


during the feeding according to the frame-sequential full-color recording. A cutter


52


is disposed between the supply roller set


42


and the feeder roller set


45


, and cuts the recording material


40


at the predetermined size into a sheet, which is then ejected. Note that, although the recording material


40


has a continuous form with a great length, it is possible to use recording sheets prepared in a regular size.




The operation of the thermal printer


11


is described. When the thermal printer


11


is initially powered, the motors


17




b


and


23


in the dust collector


10


start rotation. The propeller


17




a


is rotated by the motor


17




b


. So external air is let in the passage case


15


of the dust collector


10


through the filter


16


in the air intake port


15




a


. At this time, the filter


16


removes dust or particles of a middle or great size from the air.




The motor


23


rotates the second friction disk


22


, and rubs it on the first friction disk


21


. The first friction disk


21


is charged negatively. The second friction disk


22


is charged positively. Among particles as dust flowing in the air taken in the air intake port


15




a


, the positively charged floating fine particles


31


are attracted by the first friction disk


21


. The negatively charged floating fine particles


32


are attracted by the second friction disk


22


. The cleaned air is ejected through the air exhaust port


15




b


, sent through the duct


13


toward the heat sink assembly


35


of the thermal head


14


. Thus, the thermal head


14


is cooled.




When a printing command signal is input to the thermal printer


11


, the feeder motor


50


starts being rotated in a forward direction. The recording material


40


nipped by the supply roller set


42


is supplied into the feeding path. A front end of the recording material


40


is detected, to start counting to measure a feeding amount of the recording material


40


.




The recording material


40


is fed by the feeder roller set


45


and moved past the thermal head


14


. When a front end of the recording material


40


becomes nipped by the feeder roller set


46


, the recording material


40


is stopped. A shifting mechanism shifts the thermal head


14


, to press the heating element array


36


against the recording material


40


. The feeder motor


50


rotates forwards, to transport the recording material


40


in the advancing direction. When the beginning position of a recording region reaches the thermal head


14


, yellow recording is started.




Yellow image data is subjected to image processing for color compensation, gradation correction and the like, and converted to a signal of driving voltage levels according to gradation levels of pixels. These driving voltage levels are combined with a driving voltage level for bias heating constant for the yellow. Thus, the heating elements in the heating element array


36


are driven. Thus, the yellow coloring layer in the recording material


40


is heated to print a yellow image one line after another.




Upon the start of the yellow recording, the ultraviolet lamp


47




a


in the yellow photo fixer


47


is turned on. When the recording material


40


reaches the yellow photo fixer


47


, ultraviolet rays are applied to the recording material


40


, to fix the yellow coloring layer electromagnetically. When the fixation is completed, the shifting mechanism shifts the thermal head


14


, to move the heating element array


36


away from the recording material


40


. The feeder motor


50


is caused to rotate backwards, to transport the recording material


40


in the returning direction, Also, the ultraviolet lamp


47




a


is turned off. When the recording material


40


is wound back, a beginning position of a recording region of the recording material


40


reaches the thermal head


14


. The feeder motor


50


is stopped. The heating element array


36


is pressed against the recording material


40


. Rotation of the feeder motor


50


is changed over to the forward rotation. Also, magenta image data is converted to driving voltage levels according to magenta gradation levels of the respective pixels. These driving voltage levels are combined with a driving voltage level for bias heating constant for the magenta. Thus, the heating elements in the heating element array


36


are driven.




Upon the start of the magenta recording, the ultraviolet lamp


48




a


in the magenta photo fixer


48


is turned on. When the recording material


40


reaches the magenta photo fixer


48


, ultraviolet rays are applied to the recording material


40


, to fix the magenta coloring layer electromagnetically. When the fixation is completed, the heating element array


36


is moved away from the recording material


40


. The feeder motor


50


is caused to rotate backwards, to transport the recording material


40


in the returning direction.




When the recording material


40


is wound back, the beginning position of the recording region of the recording material


40


reaches the thermal head


14


. The feeder motor


50


is stopped. The heating element array


36


is pressed against the recording material


40


. Rotation of the feeder motor


50


is changed over to the forward rotation. Also, cyan image data is converted to driving voltage levels according to cyan gradation levels of the respective pixels. These driving voltage levels are combined with a driving voltage level for bias heating constant for the cyan. Thus, the heating elements in the heating element array


36


are driven.




When the cyan recording is completed, the recording material


40


is fed further in the advancing direction. The cutter


52


cuts the recording material


40


to obtain a sheet as a print, which is ejected externally to the tray disposed outside the thermal printer


11


.




Even at the initial time of powering the printer, the heat sink assembly


35


of the thermal head


14


is supplied with clean air by the duct


13


. The thermal head


14


can be prevented from being overheated. Heat energy of exact levels can be applied to the recording material


40


for each of the yellow, magenta and cyan colors. A full-color image can be printed with high quality by reliably reproducing the gradation.




If the electrostatic generator unit


18


is used for a long time, dust is stuck on the first and second friction disks


21


and


22


. So the dust collector


10


is cleaned periodically, one time per a month. For the purpose of cleaning, the fastening screws


25


are unfastened to remove the electrostatic generator unit


18


from the passage case


15


. The nut


29


is detached from the motor output shaft


26


, to separate the second friction disk


22


from the first friction disk


21


. Therefore, the first and second friction disks


21


and


22


can be cleaned easily and reliably. Furthermore, the screws


30


may be unfastened, so that the first friction disk


21


can be removed from the case panel


24


and can be cleaned alone. Should the first and second friction disks


21


and


22


be polluted with dirt to an irrecoverable extent, or be scratched or damaged after long use, the first and second friction disks


21


and


22


are replaced with unused disks.




In

FIG. 7

, a second preferred embodiment is illustrated. A dust collector


60


for use with a thermal printer


65


includes two electrostatic generator units


61


and


62


arranged vertically. This construction makes it possible to heighten efficiency by two times as high as that of the initial embodiment. The air can become still cleaner before the supply into a thermal printer


65


. Elements similar to those of the above embodiment are designated with identical reference numerals.




In a manner similar to the above embodiment, the electrostatic generator units


61


and


62


have the second friction disk


22


which is pressed against the first friction disk


21


by the coil spring


27


. When the second friction disk


22


rotates, the first friction disk


21


is rubbed by the second friction disk


22


with high friction. One motor


66


as moving mechanism is disposed on a side of the electrostatic generator unit


62


. An output shaft


67


of the motor


66


extends to the electrostatic generator unit


61


, is engaged with the second friction disk


22


in the electrostatic generator unit


61


, and rotates the second friction disk


22


in each of the electrostatic generator units


61


and


62


.




A passage case


72


of the dust collector


60


includes a case panel or lid panel


71


and an access opening


72




a


. The first friction disk


21


of the electrostatic generator unit


61


is attached to the case panel


71


. The access opening


72




a


receives the case panel


24


fitted therein fixedly, and has a larger size than the case panel


71


. If a user wishes to clean the first and second friction disks


21


and


22


, the combination of the electrostatic generator units


61


and


62


can be removed through the access opening


72




a


by means of the output shaft


67


connecting the two units. Also, the passage case


72


includes an access opening


72




b


and a stopper


73


. The access opening


72




b


receives insertion of the case panel


71


. The stopper


73


is formed with an outer edge of the access opening


72




b


, and regulate a position of the output shaft


67


in an axial direction that is vertical in the drawing.




In

FIG. 8

, a further preferred dust collector


80


is illustrated. A passage case of the dust collector


80


includes an upstream casing frame


81


, an intermediate casing frame


82


and a downstream casing frame


83


. The upstream casing frame


81


contains the filter


16


. There is an electrostatic generator unit


85


incorporated in the intermediate casing frame


82


. The downstream casing frame


83


contains the fan


17


. There are connection frames


86


and


87


for securing the upstream casing frame


81


and the downstream casing frame


83


to the intermediate casing frame


82


with screws. A combination of the upstream casing frame


81


, the intermediate casing frame


82


and the downstream casing frame


83


is the passage case in a quadrilateral prism. The screws on the connection frames


86


and


87


can be unfastened. Thus, the intermediate casing frame


82


can be removed from the dust collector


80


and cleaned easily. Note that there is an air intake port


81




a


through which external air is taken in. An air exhaust port


83




b


lets the air out.




The electrostatic generator unit


85


includes the intermediate casing frame


82


, a rotatable friction disk


94


as second friction device, and the motor


23


. The intermediate casing frame


82


operates as first friction device, and constitutes both of the first friction disk


21


and the case panel


24


according to the initial embodiment. The friction disk


94


is biased by the coil spring


27


toward the intermediate casing frame


82


in the same manner as the second friction disk


22


. Force of the bias of the coil spring


27


to the friction disk


94


is adjusted by the nut


29


to change the position of the flange ring


28


at the motor output shaft


26


of the motor


23


.




The intermediate casing frame


82


is formed from polytetrafluoroethylene or Teflon (trade name), and has a surface resistance of 10


9


Ω or more. Each of the upstream casing frame


81


and the downstream casing frame


83


has a surface resistance of 10


9


Ω or less. The friction disk


94


is formed from polypropylene, and has nearly a semi-circular shape. See FIG.


9


. An inner surface


82




a


of the intermediate casing frame


82


is rubbed by the friction disk


94


rotated by the motor


23


. Then the friction disk


94


is charged positively. The intermediate casing frame


82


is charged negatively. However, there is nearly no electrical charging of the upstream casing frame


81


and the downstream casing frame


83


.




Among dust particles in the air taken in the intermediate casing frame


82


, the positively charged floating fine particles


31


are attracted by the intermediate casing frame


82


. The negatively charged floating fine particles


32


are attracted by the friction disk


94


. At the same time, a dust eliminating edge portion


94




a


of the friction disk


94


in the straight shape rubs away the positively charged floating fine particles


31


lying on the inner surface


82




a


of the intermediate casing frame


82


in the course of rotations of the friction disk


94


.




The electrostatic generator unit


85


is disposed on the upside of the intermediate casing frame


82


. A dust exit path


82




b


is formed in the underside of the intermediate casing frame


82


. A dust containing case


96


is secured to the periphery of the dust exit path


82




b


in a removable manner. The dust containing case


96


is formed from plastic material having flexibility. A groove


96




a


is formed on edges of the dust containing case


96


. A ridge


97


projects from edges of the dust exit path


82




b


, and is engaged with the groove


96




a


for keeping the dust containing case


96


positioned at the dust exit path


82




b


of the intermediate casing frame


82


.




Particles or fine dust


98


is rubbed away from the inner surface


82




a


of the intermediate casing frame


82


by the dust eliminating edge portion


94




a


of the friction disk


94


, and drops and deposits in the dust containing case


96


. Then the dust containing case


96


is removed from the dust exit path


82




b


to discard all the fine dust


98


out of the dust containing case


96


. This can be performed periodically, for example one time per a month. The inside of the intermediate casing frame


82


can be kept clean readily for normal operation of the air cleaning without need of disassembly all of the passage case of the dust collector


80


.




A portion of the intermediate casing frame


82


being charged electrically is mainly located as a part of the inner surface


82




a


directly rubbed on the friction disk


94


. A potential of the charging decreases according to a distance from the portion with the highest potential. Accordingly, there is no occurrence of entire pollution of the inner surface


82




a


with dust in the intermediate casing frame


82


. Note that dust is also stuck on the surface of the friction disk


94


. However, it is likely that the dust does not drop from the friction disk


94


easily. For the purpose of clearing dust from the friction disk


94


, the dust collector


80


is periodically disassembled and cleaned, for example one time per six months. Alternatively, the friction disk


94


can be renewed periodically.




A shutter plate S


1


is incorporated in the downstream casing frame


83


in a movable manner. A path or opening


83




a


of the downstream casing frame


83


on the side of the intermediate casing frame


82


is openably closed by the shutter plate S


1


. A shutter drive device


101


is disposed on an upside of the downstream casing frame


83


, and drives the shutter plate S


1


. A shutter plate S


2


is incorporated in the intermediate casing frame


82


in a movable manner. The dust exit path


82




b


of the intermediate casing frame


82


is openably closed by the shutter plate S


2


. A shutter drive device


102


is disposed beside the intermediate casing frame


82


, and drives the shutter plate S


2


. The shutter plates S


1


and S


2


are opened and closed in an alternate manner, which will be described later in detail.




In

FIG. 10

, a circuit arrangement of a thermal printer


110


provided with the dust collector


80


is illustrated. A motor driver


112


is connected with the motor


23


in the dust collector


80


. A CPU


113


as controller causes the motor driver


112


to rotate the motor


23


. CPU


113


also controls the fan


17


of the dust collector


80


, and the shutter drive devices


101


and


102


. A thermistor


115


is associated with the thermal head


14


, obtains data of the temperature of the thermal head


14


, and sends the temperature data to CPU


113


. The thermal printer


110


includes elements similar to those in the embodiment of FIG.


6


. Such elements are herein designated with identical reference numerals.




A timer


116


is connected with CPU


113


. The timer


116


measures elapsed time T elapsed after the stop of the electrostatic generator unit


85


. Even after the electrostatic generator unit


85


stops operation, potential of the intermediate casing frame


82


and the friction disk


94


being charged remains at a sufficiently high level for collecting dust effectively for a predetermined time, for example 10 minutes. During the period of the 10 minutes, the electrostatic generator unit


85


remains stopped. After the 10 minutes, CPU


113


causes the shutter drive device


101


to close the shutter plate S


1


to stop the air from flowing; The shutter drive device


102


is driven to open the shutter plate S


2


, before CPU


113


rotates the motor


23


to drive the electrostatic generator unit


85


. Thus, the intermediate casing frame


8


Z and the friction disk


94


are caused to generate electrostatic charge. When the shutter plate S


1


is closed, the fan


17


is stopped.




When the electrostatic generator unit


85


starts being driven, the friction disk


94


is charged positively. The intermediate casing frame


82


is charged negatively. The fine dust


98


flowing in the air inside the upstream casing frame


81


and the intermediate casing frame


82


is collected by the surfaces of the intermediate casing frame


82


and the friction disk


94


. The dust eliminating edge portion


94




a


of the friction disk


94


rubs the dust away from the inner surface


82




a


of the intermediate casing frame


82


. As the shutter plate S


1


is closed to stop the flow of the air, the dust drops down from the inner surface


82




a


in a nearly vertical manner, and comes into the dust containing case


96


. Therefore, no pollution with dust occurs inside the upstream casing frame


81


, because dust is collected inside the dust containing case


96


.




The electrostatic generator unit


85


is driven for a predetermined driving time, for example 5 minutes to charge the intermediate casing frame


82


and the friction disk


94


sufficiently. After the lapse of this driving time, the motor


23


is stopped. The shutter plate S


2


is closed. Also, the shutter plate S


1


is opened. The fan


17


restarts being driven. Even when the electrostatic generator unit


85


is stopped, the charged state of the intermediate casing frame


82


and the friction disk


94


can be maintained for approximately 10 minutes. Dust in the air taken in through the filter


16


is collected by the surfaces of the intermediate casing frame


82


and the friction disk


94


. The air is cleaned and sent to the thermal head


14


through the duct


13


. Note that the sequence of those steps is repeated while the power source of the thermal printer


110


is turned on.




The thermal printer


110


also includes an image memory


121


, a work memory


122


, a thermal head driver


123


and a communication interface (I/F)


124


, which are connected with CPU


113


by a data bus


118


. The image memory


121


stores image data of an image obtained from a digital camera or the like. The work memory


122


is used by CPU


113


in operation of subjecting the image data to processing of various corrections or changes.




The communication interface


124


is connected with clients' personal computer PC


1


, PC


2


, PC


3


and so on, and a printer server


125


which is constituted by a local area network (LAN). If an instruction signal for printing is input from any one of the personal computer PC


1


, PC


2


, PC


3


and so on, the printer server


125


causes the communication interface


124


to input a printing command signal to the thermal printer


110


.




The operation of the above-constructed embodiment is described with reference to a flow chart of FIG.


11


. While the thermal printer


110


is not powered, the shutter plate S


1


of the dust collector


80


is closed. The shutter plate S


2


is open. When a power source for the thermal printer


110


is turned on, CPU


113


refers to a counted number that is information generated by the timer


116


, and calculates elapsed time T elapsed after the previous stop of operation of the electrostatic generator unit


85


. It is checked whether the elapsed time T has come up to 10 minutes.




If the thermal printer


110


is powered initially at the very beginning of operation in one day, the elapsed time T is 10 minutes or more. Then it is checked that the shutter plate S


1


is closed and that the shutter plate S


2


is opened. After this, the motor


23


starts being driven. The friction disk


94


rotates, to cause its contact surface to rub the inner surface


82




a


of the intermediate casing frame


82


. The intermediate casing frame


82


is charged negatively. The friction disk


94


is charged positively. Among particles of dust in the air in the upstream casing frame


81


and the intermediate casing frame


82


, the positively charged floating fine particles


31


are attracted by the intermediate casing frame


82


. The negatively charged floating fine particles


32


are attracted by the friction disk


94


.




At the same time as collection of the fine dust


98


, the dust eliminating edge portion


94




a


in the electrostatic generator unit


85


rubs away the fine dust


98


from the inner surface


82




a


of the intermediate casing frame


82


. The fine dust


98


drops to the inside of the dust containing case


96


. The shutter plate S


1


has been closed to stop the flow of the air. The fine dust


98


drops nearly vertically under the gravity, and does not scatter outside an area covered by the dust containing case


96


.




CPU


113


refers to the counted number as a signal output by the timer


116


. When five minutes elapse after the start of the dust collecting operation. CPU


113


stops driving the motor


23


. The shutter drive devices


101


and


102


are operated to close the shutter plate S


2


and open the shutter plate


81


. After this, the fan


17


starts being driven, and sends cooling air through the duct


13


to the thermal head


14


. During the operation of sending the cooling air, the friction disk


94


and the intermediate casing frame


82


remain at the sufficient potential obtained by charging for the dust collection. The dust collection of the friction disk


94


and the intermediate casing frame


82


continues, so that cleaned cooling air can be sent to the thermal head


14


continuously.




When 10 minutes pass after the stop of operation of the electrostatic generator unit


85


, the shutter plate Si is closed, The shutter plate S


2


is opened, to drive the electrostatic generator unit


85


. The sequence of those processes is repeated while the thermal printer


110


is powered.




The thermal head


14


is incessantly cooled. However, it data of temperature of the thermal head


14


input by the thermistor


115


to CPU


113


should become equal to or higher than a predetermined level, operation of the electrostatic generator unit


85


is stopped forcibly even during the step of a normal rotation. The shutter plate S


2


is closed. The shutter plate S


1


is opened. The fan


17


is driven to send cooling air to the thermal head


14


. The printing operation of the thermal printer


110


is the same as that according to the above-described initial embodiment.




The dust containing case


96


is removed from the dust exit path


82




b


periodically, for example one time per a month, to discard the fine dust


98


in a cumulative manner. Note that a sensor may be used for monitoring an amount of the fine dust


98


in the dust containing case


96


or the intermediate casing frame


82


. A buzzer or other alarming device may be driven for generating an acoustic signal when an amount of the fine dust


98


comes up to a predetermined high level. Furthermore, a display panel of LCD may be used in a printer body to display an indication of letters, indicia or the like. A user can be informed of an alarm state by the acoustic signal or the visible indication, and manually remove the dust containing case


96


from the dust exit path


82




b


to discard the fine dust


98


. This makes it unnecessary to check the fine dust


98


periodically.




At each time that a predetermined period elapses, for example six months, the screws on the connection frames


86


and


87


are unfastened to disassemble the dust collector


80


into the three pieces including the upstream casing frame


81


, the intermediate casing frame


82


and the downstream casing frame


83


. The inner surface


82




a


and the friction disk


94


are cleaned in a step included in a periodical maintenance. If the dirt stuck on the friction disk


94


is excessive and not recoverable, the friction disk


94


is replaced with an unused one.




In the present embodiment, the fan


17


is disposed inside the downstream casing frame


83


having the air exhaust port


83




b


of the dust collector


80


. Alternatively, the fan


17


may be positioned in the manner of

FIG. 12

, namely disposed in the upstream casing frame


81


having the air intake port


81




a


. In this construction, the shutter plate S


1


may be disposed in the downstream casing frame


83


, but can be disposed in the upstream casing frame


81


associated with the fan


17


.




In the above embodiment, the friction disk


94


in the electrostatic generator unit has a shape slightly greater than a semi-circle. Alternatively, a rotatable friction ring


127


as second friction device in

FIG. 13

may be used. The friction ring


127


has such a shape that openings are formed in the friction disk


94


and that a rotational central portion


127




a


is defined between the openings. Consequently, five dust eliminating edge portions


127




b


-


127




f


are provided in the friction ring


127


in the number higher than the one edge portion


94




a


of the friction disk


94


. Note that the friction ring


127


rotates in one direction. So three of the dust eliminating edge portions


127




b


-


127




f


are effective in rubbing dust away.




In

FIG. 14

, another preferred rotatable friction ring


128


as second friction device is illustrated. The friction ring


128


has four openings formed in a disk. The openings define eight dust eliminating edge portions


128




a


-


128




h


in a straight form for efficiently rubbing dust away. Note that the friction ring


128


rotates in one direction. So four of the dust eliminating edge portions


128




a


-


128




h


are effective in rubbing dust away.




In

FIG. 15

, another preferred rotatable friction member


129


as second friction device is depicted. The friction member


129


has a cross shape, or has a shape obtained by eliminating a ring portion from the friction ring


128


. Eight dust eliminating edge portions


129




a


-


129




h


are defined in the friction member


129


, and can rub dust away efficiently. Note that the friction member


129


rotates in one direction. So four of the dust eliminating edge portions


129




a


-


129




h


are effective in rubbing dust away. In the friction member


129


, an area of contacting the inner surface


82




a


of the intermediate casing frame


82


is smaller than that of the friction ring


128


. Although an effect of electrostatic charge being generated is smaller than the friction ring


128


, the friction member


129


has its advantage in that peripheral openness of the friction member


129


created by eliminating the ring portion makes it possible to move dust away radially from the friction member


129


.




It is to be noted that a movable friction device can have a shape other than those depicted in

FIGS. 9

,


13


,


14


and


15


. A movable friction device can have any suitable shape or structure that can frictionally contact the stationary friction device or the intermediate casing frame


82


and can rub dust away from it.




In the above embodiments, Teflon (trade name) and polypropylene are selected as substances for contacting each other frictionally to generate charge. However, two different substances of any suitable combination can be selected in positions in the triboelectric series of substances. However, it is known that an effect of charging by frictional contact of two substances in the triboelectric series is lower according to closeness between those in the triboelectric series. So it is necessary that two substances to be selected should be in positions sufficiently distant from each other within the triboelectric series. In the first of the preferred embodiments herein, the first friction disk


21


of Teflon (trade name) is fixed on the case panel


24


by use of the screws. However, a tape of Teflon (trade name) may be used, and attached to the case panel


24


in a fixed manner.




In the above embodiments, the second friction disk


22


, the friction disk


94


, the friction rings


127


and


128


and the friction member


129


are formed from polypropylene, and is movable. The first friction disk


21


and the intermediate casing frame


82


are formed from Teflon, and is stationary. However, a movable friction device may formed from Teflon. A stationary friction device may be formed from polypropylene.




In the initial one of the above embodiments, the first friction disk


21


stationary in the passage case


15


is in a circular shape. However, the first friction disk


21


may be replaced by a plate of a quadrilateral or other form. In the above embodiments, the flat contact surfaces of the first and second friction devices are contacted on each other in a face-to-face manner. However, a combination of the first and second friction devices may be two rollers, or a roller and a flat surface, or the like. In the above embodiments, the second friction disk


22


, the friction disk


94


, the friction rings


127


and


128


and the friction member


129


as second friction device are rotatable. However, a second friction device may be movable back and forth in a straight manner for rubbing a first friction device kept stationary. In the above embodiments, the electrostatic generator units


18


,


61


,


62


,


85


are disposed on the upper panel or the lower panel. However, the electrostatic generator units


18


,


61


,


62


,


85


may be disposed on any one of lateral panels of the passage case


15


,


72


or the intermediate casing frame


82


which extend vertically.




In the initial preferred embodiment, the electrostatic generator unit


18


is disposed in the downside of the passage case


15


. However, the electrostatic generator unit


18


may be disposed in the upside of the passage case


15


. The dust containing case


96


similar to that of the third embodiment may be disposed in the downside of the passage case


15


. In the above embodiments, the dust containing case


96


has a box shape. However, the dust containing case


96


can have a semi-spherical shape for the purpose of receiving the fine dust


98


. In the third of the embodiments, the upstream casing frame S


1


, the intermediate casing frame


82


and the downstream casing frame


83


are connected one another by the connection frames


86


and


87


. However, any fastening structure may be used for connecting the upstream casing frame


81


, the intermediate casing frame


82


and the downstream casing frame


83


. The upstream casing frame


81


, the intermediate casing frame


82


and the downstream casing frame


83


may be connected in a manually removable manner, for example by engagement of ridges and grooves. Furthermore, those may be connected by clips, clamps, or other fastening devices for fastening in a manually detachable manner. In the above embodiments, the electrostatic generator unit


18


,


61


,


62


,


85


is disposed between the filter


16


and the fan


17


. However, the fan


17


can be disposed sear to the filter


16


. See FIG.


12


. The electrostatic generator unit


18


,


61


,


62


,


85


may be positioned downstream from the fan


17


.




In the third of the above preferred embodiments, the driving time of the electrostatic generator unit


85


is set five minutes. The air supply time for supply cooling air to the thermal head


14


is set 10 minutes. The period of discarding the fine dust


98


from the dust containing case


96


is set one month. The period of disassembly and cleaning of the dust collector


80


is set six months. However, any of those values can be changed as required




In the third of the embodiments, the motor


23


, the fan


17


, and the shutter plates S


1


and S


2


are controlled by CPU


113


in the thermal printer


110


. However, a control unit may be incorporated in the dust collector


80


for controlling those elements without being controlled by the thermal printer


110


. It is preferable to control the dust collector


80


to administrate the temperature of the thermal head


14


precisely. To this end, CPU


113


of the thermal printer


110


should be preferably connected with the control unit of the dust collector


80


by a communication system, which enables total control of the combination of the dust collector


80


and the thermal printer


110


.




All of the above-described dust collectors are used in the thermal printer. However, a dust collector or air cleaner according to the invention may be used with devices for any purpose.




Although the present invention has been fully described by way of the preferred embodiments thereof with reference to the accompanying drawings, various changes and modifications will be apparent to those having skill in this field. Therefore, unless otherwise these changes and modifications depart from the scope of the present invention, they should be construed as included therein.



Claims
  • 1. A dust collector for collecting fine dust in air and for cleaning said air, comprising:a first friction member produced from a first substance; a second friction member produced from a second substance that is chargeable triboelectrically in a polarity different from a polarity of said first substance; a friction driving mechanism which moves one of said first and second friction members relative to a remaining one thereof, and which frictionally generates electrostatic charge, to attract said fine dust and attendantly provide clean air for a cooling function; a passage case for defining a path of said air, having an air intake port and an air exhaust port, wherein said first and second friction members are disposed between said air intake port and said air exhaust port and overlapped with one another; and a fan for flowing of said air in said passage case, wherein said first or second friction member attracts said fine dust electrostatically while said air flows in said passage case.
  • 2. A dust collector as defined in claim 1, wherein said first substance is polytetrafluoroethylene.
  • 3. A dust collector as defined in claim 1, wherein at least one of said first and second substances has a surface resistance of 109 Ω or higher.
  • 4. A dust collector as defined in claim 1, further comprising a filter disposed close to said air intake port.
  • 5. A dust collector as defined in claim 4, wherein said air intake port lets in said air from an outside of an instrument, and said air exhaust port ejects said air to blow and cool a heat generating portion of said instrument.
  • 6. A dust collector as defined in claim 5, wherein said instrument is a thermal printer, and said heat generating portion is a thermal head.
  • 7. A dust collector as defined in claim 4, wherein said first friction member is stationary in said passage case, said second friction member is uncovered in said path inside said passage case;said driving mechanism rotates said second friction member.
  • 8. A dust collector as defined in claim 7, wherein said first and second substances have such characteristics as to be charged respectively in negative and positive states when frictionally contacted on one another.
  • 9. A dust collector as defined in claim 7, wherein said driving mechanism includes:a rotational shaft for rotating said second friction member, said rotational shaft being slidable relative to said second friction member, and inserted loosely in said first friction member; a motor for rotating said rotational shaft; and a bias mechanism for pressing said second friction member against said first friction member.
  • 10. A dust collector as defined in claim 9, wherein said first friction member is plate-shaped, and said second friction member is disk-shaped, or substantially semi-circular and plate-shaped, or cross-shaped.
  • 11. A dust collector as defined in claim 9, wherein said rotational shaft includes a flange, disposed on a portion thereof inserted through said second friction member, and said bias mechanism is disposed between said flange and said second friction member.
  • 12. A dust collector as defined in claim 11, wherein said passage case includes;an opening; and a first case panel, secured to an inside of said opening in a removable manner, having an inner surface to which said first friction member is secured fixedly, having an outer surface to which said motor is secured fixedly, and having a hole through which said rotational shaft extends.
  • 13. A dust collector as defined in claim 12, wherein said passage case has a box shape, having upper and lower panels, said first case panel is associated with said upper panel;further comprising: a second case panel associated with said lower panel; a third friction member secured to said second case panel; and a fourth friction member for contacting said third friction member, for being rotated by said rotational shaft, to charge triboelectrically with said third friction member.
  • 14. A dust collector as defined in claim 11, wherein said passage case includes an opening for securing of said first friction member thereto in a removable manner, said first friction member has an inner surface on which said second friction member is disposed, and has an outer surface to which said motor is secured fixedly.
  • 15. A dust collector as defined in claim 9, further comprising a dust eliminating portion for rubbing away said fine dust stuck on said first or second friction member.
  • 16. A dust collector as defined in claim 15, wherein said dust eliminating portion is constituted by an edge portion of said second friction member extending crosswise to a rotational direction, for rubbing away said fine dust from said first friction member upon rotation of said second friction member.
  • 17. A dust collector as defined in claim 16, wherein said first and second friction members are disposed at an upper panel of said passage case disposed on an upside;further comprising a container, disposed under said passage case, for receiving said fine dust being rubbed away.
  • 18. A dust collector as defined in claim 17, wherein said passage case includes:an intermediate casing frame provided with said first and second friction members and said container; an upstream casing frame, connected with said intermediate casing frame on an upstream side, for containing said filter; and a downstream casing frame, connected with said intermediate casing frame on a downstream side, for containing said fan.
  • 19. A dust collector as defined in claim 18, further comprising:a first shutter for closing said path of said air openably; a second shutter for closing a passage port of said container openably; a controller for setting an alternately selected one of first and second shutter modes, wherein said controller, while said first shutter mode is set, closes said second shutter and opens said first shutter, and drives said fan to eject said air from said passage case, and while said second shutter mode is set, closes said first shutter and opens said second shutter, and actuates said driving mechanism to attract said fine dust.
  • 20. A dust collector as defined in claim 19, wherein said controller sets said first shutter mode while said first and second friction members remain electrostatically charged sufficiently for attracting said fine dust, and sets said second shutter mode while said first and second friction members become electrostatically charged at a predetermined level.
  • 21. A dust collector as defined in claim 20, wherein a surface resistance of said intermediate casing frame is higher than a surface resistance of said upstream and downstream casing frames, and is 109 Ω or higher.
  • 22. A dust collector as defined in claim 19, wherein said second friction member is D-shaped.
  • 23. A dust collector as defined in claim 19, wherein said second friction member includes a plurality of openings having a sector shape.
  • 24. A dust collector as defined in claim 19, wherein said second friction member includes a plurality of arm portions extending in different directions from a rotational axis, and a ring portion for connecting ends of said arm portions.
  • 25. A dust collector as defined in claim 20, wherein said second friction member includes a plurality of arm portions extending in different directions from a rotational axis.
  • 26. A dust collector for collecting fine dust in air and for cleaning said air, comprising:a first friction member produced from a first substance; a second friction member produced from a second substance that is chargeable triboelectrically in a polarity different from a polarity of said first substance; a friction driving mechanism for moving one of said first and second friction members relative to a remaining one thereof and for frictionally generating electrostatic charge, including: a rotational shaft including a flange disposed on a portion thereof inserted through said second friction member, said rotational shaft being slidable relative to said second friction member and inserted loosely in said first friction member; a motor for rotating said rotational shaft; and a bias mechanism disposed between said flange and said second friction member and for pressing said second friction member against said first friction member; wherein said driving mechanism rotates said second friction member; a passage case for defining a path of said air, having an air intake port and an air exhaust port, wherein said first and second friction members are disposed between said air intake port and said air exhaust port and overlapped with one another; a fan for flowing of said air in said passage case, wherein said first or second friction member attracts said fine dust electrostatically while said air flows in said passage case and wherein said first friction member is stationary in said passage case and said second friction member is uncovered in said path inside said passage case; and a filter disposed close to said air intake port.
  • 27. A dust collector for collecting fine dust in air and for cleaning said air, comprising:a first friction member produced from a first substance; a second friction member produced from a second substance that is chargeable triboelectrically in a polarity different from a polarity of said first substance; a friction driving mechanism for moving one of said first and second friction members relative to a remaining one thereof and for frictionally generating electrostatic charge, including: a rotational shaft for rotating said second friction member, said rotational shaft being slidable relative to said second friction member and inserted loosely in said first friction member; a motor for rotating said rotational shaft; and a bias mechanism for pressing said second friction member against said first friction member; a passage case for defining a path of said air, having an air intake port and an air exhaust port, wherein said first and second friction members are disposed between said air intake port and said air exhaust port and overlapped with one another; a fan for flowing of said air in said passage case, wherein said first or second friction member attracts said fine dust electrostatically while said air flows in said passage case and wherein said first friction member is stationary in said passage case and said second friction member is uncovered in said path inside said passage case; a filter disposed close to said air intake port; and a dust eliminating portion for rubbing away said fine dust stuck on said first or second friction member, wherein said dust eliminating portion is constituted by an edge portion of said second friction member extending crosswise to a rotational direction and for rubbing away said fine dust from said first friction member upon rotation of said second friction member.
Priority Claims (1)
Number Date Country Kind
2001-352137 Nov 2001 JP
US Referenced Citations (13)
Number Name Date Kind
2184732 Brewer Dec 1939 A
2282770 Sarver May 1942 A
3105750 Kayko et al. Oct 1963 A
3421216 Anna Jan 1969 A
3493109 Carta et al. Feb 1970 A
3616604 Schouw Nov 1971 A
3982043 Simpson Sep 1976 A
4378980 Long Apr 1983 A
5681374 Von Glehn Oct 1997 A
5885330 Lee Mar 1999 A
5888274 Frederick Mar 1999 A
6090189 Wikstrom et al. Jul 2000 A
6193788 Nojima Feb 2001 B1
Foreign Referenced Citations (3)
Number Date Country
4-171065 Jun 1992 JP
6-103745 Apr 1994 JP
10-323580 Dec 1998 JP