Patent Publication Number: US-9421588-B2

Title: Anti-cleanser dispersing element, object holder, and dry washing device

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is based on and claims priority from Japanese Patent Application No. 2011-235272, filed on Oct. 26, 2011 and No. 2012-142248, filed on Jun. 25, 2012, the disclosure of which is hereby incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a dry washing device to wash an object by dispersing a cleanser to collide with the object, an object holder used in the dry washing device, and an anti-cleanser dispersing element set in the object holder. 
     2. Description of the Related Art 
     To manufacture print circuit boards, in soldering process with a flow soldering tank, a masking jig is often used for masking an area of a board other than that to be soldered. Such a masking jig is a plate with openings called dip palette or flow palette. It is necessary to periodically wash the surfaces of the jig to remove fluxes accumulated thereon in a repeated use, which decrease masking accuracy. 
     To remove fluxes or adhesives from an object such as jig, the top and bottom surfaces of the object is washed with an injected solvent in a tank, rinsed with water to remove the solvent, and dried with warm air. However, washing the object with a solvent by a washing machine not only uses a large amount of solvent but also consumes a large amount of energy for the disposal of liquid waste containing the fluxes and the drying process. This increases manufacturing costs and brings a large load on the environment. 
     To deal with the problem, a dry washing machine is available which blasts off a solid, light-weight, dispersive cleanser in a washing tank at a high speed, allows the cleanser to continuously contact or collide with an object, and separates attached matters on the object without using a solvent. This dry washing machine can effectively clean the object with a small amount of solvent by circulating the cleanser in the washing tank to repeatedly collide with the object. Especially, by use of a cleanser of a thin flexible plate-like shape, it can exert cleaning performance with a less amount of cleanser as much as that of ultrasonic cleaning. 
     For example, Japanese Patent No. 4531841 discloses a washing device having a downsized washing tank which can efficiently wash an object with uneven surfaces with a dispersed cleanser by placing the object outside the washing tank and sliding it relative to the opening of the tank. This device can prevent the cleanser from leaking to outside the tank and properly return it to the tank area so that it can maintain the number of cleanser particles to collide with the object and exert good, stable cleaning performance. 
     Specifically, referring to  FIG. 15 , this device comprises a semi-cylindrical washing tank  6  with an opening  6   a  and an object holder  3 . The holder  3  holding a flow palette  4  is set on the opening  6   a  of the tank. It also includes a pool portion  19  on the side of the opening in which the cleanser is accumulated. While the holder  3  is holding the object  4 , the pool portion is moved in horizontal direction in the drawing. A cleanser  5  is a thin resin plate but is represented by circles in the drawing for better understanding. 
     An acceleration nozzle  11  is provided on the center of the bottom of the washing tank  6  to inject air streams to disperse the cleanser  5  and remove the fluxes from the object  4 . The cleanser is absorbed into a suction duct  18  connected with a not-shown suction unit, returned to the washing tank  6  and used again. Further, the cleanser  5  which has lost motion energy and has been accumulated in the pool portion  19  is returned to the washing tank by a scraper  26  provided on the bottom surface of the object holder  3 . 
     The object holder  3  is a plate longer than the object  4  and includes at the center a concave portion  23  in a form in conformity with the shape of the object  4 . The concave portion  23  is made from an elastic material such as polyurethane rubber or foamed resin and the object  4  is pressed into the concave portion  23  and held by friction. The object holder is configured to tightly hold the object with no gap to prevent the cleanser from clogging and not to leak the air streams. This aims to prevent the cleanser accelerated by compressed air from scattering from the openings of the flow palette and maintain the cleaning performance of the washing tank. 
     Referring to  FIG. 16 , a description is made on how to set the object  4  in the opening of the washing tank. The object  4  is pressed into the concave portion  23  of the holder  3  and the holder is reversed and set in the pool portion  19  of a tank unit  2 . The holder  3  is slid by a not-shown moving mechanism to move the surface of the object for washing.  FIG. 16  shows a linear guide  20  and a side guide  21  of the pool portion  19 . 
     However, the object holder of the above machine faces problems as follows: 
     1. Since the concave portion of the holder is formed in accordance with the shape of a specific object, it cannot hold objects of different shapes and is lack of general versatility. Different holders need to be prepared for different objects. 
     2. It is troublesome to reverse the object to face the washing tank after setting it in the holder. Also, it will be difficult to reverse a large object, which requires labor. 
     3. Holding the object by friction is not stable, and the object may be suctioned by negative pressure in the tank and come off from the holder. 
     For the above reasons, a frame type object holder including a cover for closing only the opening of a washing tank and pins to partially hold an object is mostly in practical use. An object is placed from above in the frame of this holder fixed in a washing machine and supported by the pins on the bottom surface of the frame. The size of the frame is designed to match with the outer shape of an object. To hold a different object of a different outer shape, one side of the frame is slid for size adjustment. For a flow palette as a cleaning object, an operator first sets a printed circuit board or a plate of the same size as that of the printed circuit board on the surface of the flow palette opposite to the one to wash, to cover the openings of the flow palette. Then, the operator places the flow palette and the plate in the frame, and fixes them with the pins. The openings of the flow palette are closed with the plate and the side faces thereof are tightly attached to the inner surfaces of the object holder with no gap from which the cleanser can be scattered. Thus, the plate functions as an anti-cleanser dispersing element. 
     However, this kind of holder faces the following problems:
     1. It cannot deal with objects of different lateral and longitudinal sizes.   2. It cannot deal with objects of shapes other than rectangular.   3. It is troublesome to change the plate for washing different kinds of objects.   

     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an anti-cleanser dispersing element which can be easily set and prevent a cleanser from dispersing irrespective of different surface shapes of objects to wash and makes it easier to hold the object relative to a washing device. 
     According to one embodiment, provided is an anti-cleanser dispersing element for use in a dry washing device which disperses cleanser by an air stream to allow the cleanser to collide with an object for washing. The anti-cleanser dispersing element is disposed on a side of a holder of the object opposite to a side with which the cleanser collides. The anti-cleanser dispersing element is configured to be deformed by its own weight or pressure in accordance with an outer shape of the object, to tightly attach to the object with no gap and prevent the cleanser from moving to the opposite side of the holder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, embodiments, and advantages of the present invention will become apparent from the following detailed description with reference to the accompanying drawings: 
         FIG. 1  is a schematic cross section of the essential part of a dry washing device according to a first embodiment of the present invention; 
         FIG. 2  is a schematic cross section of an anti-cleanser dispersing element; 
         FIG. 3A  shows that the anti-cleanser dispersing element is inserted in the object holder, and  FIG. 3B  shows that it is deformed with pressure; 
         FIG. 4  shows the use of a non-deformable element as an anti-cleanser dispersing element; 
         FIG. 5A  shows an anti-cleanser dispersing element according to a second embodiment before inserted into the object holder and  FIG. 5B  shows the same when deformed by its own weight; 
         FIG. 6A  is a plan view of the structure of an area adjuster,  FIG. 6B  shows an object holder on which an object is mounted after adjusting the area, and  FIG. 6C  shows the holder in which the anti-cleanser dispersing element is set; 
         FIG. 7  is a cross section of the object holder along Y 1  to Y 1  line in  FIG. 6C ; 
         FIG. 8  is a perspective view of another example of the object holder; 
         FIG. 9A  shows a dry washing device according to a fourth embodiment in which an anti-cleanser dispersing unit is opened, and  FIG. 9B  shows the same in which the dispersing unit and a shutter are closed to be ready for washing; 
         FIG. 10A  is a plan view of the anti-cleanser dispersing unit in which an object is held and  FIG. 10B  is a cross section view of the same along Y 2  to Y 2  line in  FIG. 10A ; 
         FIG. 11  is a schematic front view of a dry washing device according to a fifth embodiment; 
         FIG. 12  is a schematic side view of the dry washing device in  FIG. 11 ; 
         FIG. 13A  is a schematic front view of the dry washing device in use when the object is discharged, and  FIG. 13B  is a cross section view of the same along Y 3  to Y 3  line in  FIG. 13A  when the cleanser is blown off; 
         FIG. 14A  is a side view of a dry washing device according to a sixth embodiment in washing operation without the object holder,  FIG. 14B  is a front view of the same in washing operation, and  FIG. 14C  is a plan view of a washing unit with a trajectory of a moving washing unit; 
         FIG. 15  is a cross section view of the essential part of a related art dry washing device; and 
         FIG. 16  perceptively shows how to set an object in the dry washing device in  FIG. 15 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     First Embodiment 
     A first embodiment is described with reference to  FIGS. 1 to 4 .  FIG. 1  shows the essential part of a dry washing device  1  according to the present embodiment which comprises a washing tank unit  2  and an object holder  12 . The washing tank unit  2  includes a tank  6 , a cleanser accelerator  7 , a pool  19 , a separator  10  and a void  8 . The separator  10  faces a suction duct  18  and the void  8  is formed between the separator  10  and the suction duct  18  to expand to outside from the tank  6 . The tank  6  is in a semi-cylindrical shape with an opening  6   a  at the top. The void  8  with a half-circular cross section extends along the length of the tank  6 . The separator  10  includes a large number of small holes or slits through which gaseous matter and powder particles pass but a cleanser cannot. The separator  10  is made of a porous element such as metal net, plastic net, mesh, punching metal, or slit plate, for example, to be a smooth shape not to allow the accumulation of the cleanser. The tank  6  can be of a double structure including the separator therein. 
     The separator  10  is connected to the suction duct  18  via the void  8  and the duct  18  is connected to a not-shown a suction unit which is configured to suction the sufficient amount of air from the tank relative to the amount of air blown from an accelerator nozzle  11  via the duct and separator and keep the tank under a negative pressure. The cleanser accelerator  7  includes an accelerator nozzle  11  with outlets and a not-shown compressed air supply unit as a compressor. The accelerator nozzle  11  is disposed so that the outlets are aligned in a straight line along the center of the tank bottom. The accelerator nozzle  11  is connected via an air pipe with a control valve to the compressed air supply unit which supplies compressed air to the nozzle to blast off the cleanser  5 . 
     The pool  19  is in a concave shape, has a certain length and is provided at both sides of the tank. It has, at the corner of a level surface, a linear guide  20  as a rectangular column made from a smooth material such as fluorine resin with a thickness of about 5 mm, for example. The linear guide  20  works to hold the object holder  12  and guide it to move horizontally in the drawing together with a side guide  21 . The holder  12  is connected with a not-shown driver such as DC motor, air cylinder, or wire driver and moved by the driver according to a control signal from a not-shown controller along the pool in parallel to the operation of the washing tank unit. The size of the pool is equal to or larger than the moving range of the object held by the holder. 
     The object holder  12  comprises a frame  14  to hold the object, facing the opening  6   a  and a pressure element  24  to apply pressure to an anti-cleanser dispersing element  22 A held in the frame  14 . The contour of the frame  14  is larger than the size of the opening  6   a  and includes a base  28  as a rectangular frame to cover the upper part of the opening  6   a  and walls  30  standing on the four sides of the base  28 . The walls  30  are rectangular frames formed by plate folding processing and include top ends folded outward to easily insert the anti-cleanser dispersing element  22 A in the frame  14 . Pins  32  are provided on the opposite sides of the base  28  to protrude inward and support the object  4 . An anti-leakage element  34  is provided on the bottom face of the base  28  to return the cleanser accumulated in the pool  19  to the tank  6 . The anti-leakage element  34  is made of a brush with dense hairs to allow airflow but prevent the leakage of the cleanser  5 . 
     The pressure elements  24  are toggle clamps each including a support element  36  fixed to the base  28 , an arc arm  38  rotatably supported by the support element  36 , and an adjusting pad  40  attached to the tip end of the arm  38  via a screw shaft. The arms  38  are rotated to press the anti-cleanser dispersing element  22 A and the pressed elements  24  are locked by a not-shown lever. The pressure elements  24  are disposed at four positions, facing each other ( FIG. 8 ) to be able to press the maximum support area of the frame  14  relative to the object  4 . The pressure is equalized at the four positions by adjusting the positions of the pads  40 . The position of the support elements  36  relative to the base  28  can be fixed or it can be fixed with a detachable screw to change pressure positions. 
     In  FIG. 2  the anti-cleanser dispersing element  22 A is comprised of a core element  42  to deform in accordance with the outer shape of the object  4 , a plastic plate  44  with rigidity disposed on the face opposite to that with which the cleanser  5  collides, and a surface layer  46  to cover at least the core element  42 . The surface layer  46  is made from an anti-wear material to protect from the collision of the cleanser  5  and not to inhibit the deformability of the core element  42 . In the rest of the drawings the surface layer  45  may be omitted. In the present embodiment the core element  42  is made of a low repulsive urethane sponge, and the surface layer  46  is made from a stretch material and the top end thereof is fixed to the plate  44  by adhesion. The anti-cleanser dispersing element  22 A functions as an individual unit separately from the dry washing device  1 . Herein, low repulsive property refers to low repulsive elasticity of 15% or less (JIS K64003) in a precise sense and a low repulsive foamed material is continuous bubbles composed of polyurethane resin, for example. 
     The core element  42  is inherently soft and not easily used. However, integrated with the rigid plate  44 , its usability is improved. The plate  44  is also an interface to apply pressure evenly to the entire core element  42  at a small number of pressure points (four in the present embodiment). 
     Next, the washing operation of the dry washing device  1  according to the present embodiment is described referring to  FIGS. 3A, 3B . First, the proper amount of the cleanser  5  to wash the object  4  is poured in the tank  6 . The proper amount is preset through experiments. Then, as shown in  FIG. 3A , the object  4  as a flow palette is inserted into the frame  14  and supported by the pins  32 . The anti-cleanser dispersing element  22 A is placed on the flow palette  4  in the frame  14 . With a small gap between the frame  14  and the anti-cleanser dispersing element  22 A, it can be easily inserted in the frame  14 . The bottom face of the anti-cleanser dispersing element  22 A inserted in the frame  14  is restricted by the highest protrusion  4   a  of the flow palette  4  to prevent the cleanser from being dispersed upward to outside of the frame  14 . However, the cleanser  5  flows through the gap between the frame  14  and both ends of the flow palette  4  and the opening  4   b  of the flow palette and becomes accumulated on the flow palette  4 . Thus, the amount of the cleanser  5  is reduced over time and its cleaning performance is degraded accordingly. In  FIG. 3A  the palette  4  includes strips  4   d  to be placed on the pins  32 . 
     The anti-cleanser dispersing element  22 A is inserted in the frame  14  and pressed and locked by the pressure elements  24 . The core element  42  is deformed by the pressure in accordance with the outer shape of the flow palette  4  as shown in  FIG. 3B . The surface layer  46  is also deformed along with the core element  42 . Therefore, the anti-cleanser dispersing element  22 A can be deformed with different heights of the protrusions  4   a  and  4   c , thereby closing the opening  4   b  and the gap between the flow palette  4  and the frame  14 .  FIG. 4  shows a rubber or rigid plate  50  provided to enclose the flow palette  4  in the frame  14 . However, the plate  50  cannot prevent the cleanser  5  from being accumulated on the top surfaces of the flow palette  4  and strips  4   d , and the amount of the cleanser  5  is reduced accordingly. 
     As shown in  FIG. 3B , the anti-cleanser dispersing element  22 A according to the present embodiment tightly encloses the flow palette  4  so that it can prevent the accumulation of the cleanser  5  and certainly return the one not colliding with the flow palette  4  to the tank  6 . Further, the anti-cleanser dispersing element  22 A is arbitrarily deformable in accordance with any shape of the object  4 , which eliminates the necessity to prepare different elements for objects of different shapes. Various elements are arranged on the top surface of the flow palette to fix a print circuit board. The low repulsive sponge and stretch material are flexibly deformed to be able to tightly enclose the opening  4   b . The object does not receive a large load from the low repulsive sponge even if it is pressed thereby. Moreover, applied with pressure, the anti-cleanser dispersing element  22 A is deformed to closely attach to the inner surface of the frame  14  with no gap, preventing a decrease in blast-off speed of the cleanser  5  due to an air leakage. 
     When the anti-cleanser dispersing element  22 A is locked with pressure, a closed space in which the cleanser is dispersed is formed between the flow palette  4  and tank  6 . Then, the air is suctioned from the space by the suction unit driven by a not-shown controller. The controller drives the compressed air supply unit to supply compressed air to the accelerator nozzle  11  and generate a vertically upward air stream. By the air stream, the cleanser  5  is blasted off to collide with the flow palette  4  and efficiently remove attached flux from the surface of the flow palette  4 . After the collision, the cleanser  5  drops by the air stream and gravity, and slides down near the accelerator nozzle  11  while suctioned over the separator  10 . Thereby, attached powder fluxes on the flow palette are suctioned, separated by the separator  10  and collected by the suction unit through the duct  18 . Further, the cleanser having dropped near the accelerator nozzle  11  is blasted off vertically upward again by the air stream from the accelerator nozzle  11 . The dry washing device  1  repeats this operation to remove attached fluxes on the surface of the flow palette. 
     While the flow palette  4  is being cleaned with the cleanser  5 , a part of the cleanser enters the gap between the pool  19  and the object holder  19 . However, the anti-leakage element  34  under the object holder  12  can block the cleanser from leaking to the outside of the washing device  1 , allowing the cleanser to be accumulated on the pool  19 . The cleanser on the pool  19  is scraped by the anti-leakage element  34  along with the reciprocating movement of the object holder  12 , returned to the tank  6 , and blasted off vertically upward again by the air stream from the accelerator nozzle  11 . 
     Thus, the anti-cleanser dispersing element  22 A eliminates the gap in which the cleanser  5  is scattered upward so that the cleanser  5  can be recirculated in the tank  6  and over the pool  19  without reduction in amount. Because of this, the washing device does not decrease in cleaning performance due to a lack of the cleanser even in operation over a long time. Accordingly, it is made possible to certainly clean even large-size flow palettes by reciprocatively moving the object holder  12  relative to the tank  6 . 
     The anti-cleanser dispersing element  22 A can be made of the core element  42  alone without the surface layer  46 . However, it was found by experiment that the low repulsive urethane sponge as the core element  42  is easily damaged by the collision with the cleanser  5 . A large damage impairs the deformability of the core element. In the present embodiment the two different elements work for deformability and anti-wear separately, aiming for preventing early degradation of the anti-cleanser dispersing element  22 A. The surface of the urethane sponge can be formed with coating having anti-wear property and no hindrance to the deformability of the urethane sponge. 
     The anti-wear property of the surface layer  46  of a stretch material does not continue for good and will be degraded over repeated use. A replaceable surface layer  46  is more cost-effective than the replacement of the entire element  22 A. 
     Further, according to the present embodiment the top end of the surface layer  46  is fixed to the plate  44 . It can be formed to be detachable with a loop fastener for replacement. Alternatively, it can be formed in a bag to wrap around the core element  42  and plate  44  and attached/detached by closing/opening the fastener. The present embodiment describes the use of low repulsive urethane sponge as the core element  42  by way of example. However, it can be an arbitrary element such as fluid as air or water or powder or powdery matter as long as a necessary deformability is acquired. 
     The cleanser  5  possesses a pencil hardness (measured under JIS K-56005-4) equal to or larger than that of attached fluxes and a folding strength of 45 or less (measured under JIS P8115). It cracks and creates new edges when continuously given an impact to thereby maintain flux removing performance. In the present embodiment the cleanser  5  is a thin rectangular strip in size of 1 to 100 mm 2  and thickness of 0.05 to 0.2 mm, however, they should not be limited thereto The size, thickness, and material of the cleanser can be arbitrarily determined depending on the object. 
     The thin-strip cleanser is very small in mass relative to air resistance so that it is easily accelerated and dispersed by an air stream flowing in a direction of a large project area. Also, air resistance is small in a direction of a small project area so that the cleanser floating in this direction can maintain fast motion over a long distance. This increases the energy of the cleanser and the force acting on the object, resulting in effectively removing attached matter on the surface of the object and enhancing the cleaning efficiency since repeated circulation of the cleanser increases the frequency at which it contacts the object. 
     Second Embodiment 
       FIGS. 5A, 5B  show an anti-cleanser dispersing element  22 B according to a second embodiment. Only differences from the element  22 A in the first embodiment are described. In the second embodiment the anti-cleanser dispersing element  22 B is deformed by use of the weight of the core element  42  instead of the pressing of the pressure elements  24 . The core element  42  according to the second embodiment is a soft bag such as a plastic bag containing granular elements such as beads. The plate  44  is provided with a handle  52  to allow an operator to hold up the anti-cleanser dispersing element and pull it down in the frame  14 . The anti-cleanser dispersing element  22 B is deformed by its own weight on the flow palette  4  as shown in  FIG. 5B  and can prevent the cleanser from dispersing effectively as the element  22 A in  FIG. 3B . 
     The anti-cleanser dispersing element  22 B does not need the pressure elements, which eliminates the necessity for the operator to operate (lock or unlock) the pressure elements. It may be troublesome to handle the element  22 B containing the beads but elevating and lowering the element  22   b  can be automated with a crane mechanism provided in the washing device. Alternatively, to omit the pressure elements  24 , the plate  44  can be omitted or decreased in size and a horizontal protrusion is provided around the inner surfaces of the walls  30  to narrow the size of the opening of the frame  14 . Then, the anti-cleanser dispersing element as a low repulsive urethane sponge is manually pressed into the frame and deformed. The protrusion functions to stop the element from restoring the original shape and maintain the deformation thereof. 
     Third Embodiment 
     A third embodiment is described with reference to  FIGS. 6A to 6C .  FIG. 7 . The features of the present embodiment are in the frame  14  including an area adjuster  54  to adjust the size of an area of the frame  14  in which the object  4  is supported in accordance with the size of the object  4 . As described above, the outer shapes (even or uneven) and horizontal and vertical sizes of the object  4  are various. In view of dealing with objects of various sizes, the area adjuster  54  is provided on one side of the base  28 . The area adjuster  54  includes an adjustment shaft  56  to insert into the one side of the base  28  and slidable horizontally in the drawings, a movable plate  58  provided at an end of the adjustment shaft  56 , and pins  32  fixed on the surface of the movable plate  58 . 
     For cleaning a smaller object  4  than the opening size (maximum support area) of the frame  14 , the movable plate  58  is moved in parallel by the manipulation of the adjustment shaft  56  to narrow the support area in accordance with the size of the object  4 , as shown in  FIG. 6A . Thus, flow palettes smaller than the frame can be properly secured in the frame  14 .  FIG. 6B  shows the object  4  placed on the pins  32  after adjustment. The size of the anti-cleanser dispersing element  22  is unchanged to cover the maximum support area in  FIG. 6C , even if a very small object  4  is subjected to cleaning. 
       FIG. 7  shows the cross section of the frame  14  in  FIG. 6C  along Y 1  to Y 1  line. The size of the anti-cleanser dispersing element  22  corresponds with the maximum support area irrespective of a change in the size of the support area. When pressed by the pressure elements  24 , the anti-cleanser dispersing element is arbitrarily deformed to close a space X in which no object is present, so as to prevent the cleanser  5  from being dispersed upward and reducing in the amount. 
     Depending on the size of the object  4 , a space is created in the lower part of the support area but it can be similarly closed by the deformed anti-cleanser dispersing element  22 . Alternatively, a frame  140  can be configured of the base  28  also functioning as the walls  30  and the area adjuster  54  can include plural adjustment shafts  56  (three in the drawing) for stable adjustment, as shown in  FIG. 8 . The adjustment shafts  56  are connected via a connection plate  55  outside the frame  140 . Although not shown, the pins  32  are provided on the bottom of the front surface of the movable plate  58 . The position of the adjusted support area is fixed by fixing the center adjustment shaft  54  with a screw  57 . 
     Fourth Embodiment 
     A fourth embodiment is described referring to  FIGS. 9A, 9B  and  FIGS. 10A, 10B . In the fourth embodiment the anti-cleanser dispersing element is integrated with the object holder instead of separated as in the above embodiments, for the purpose of more reliably preventing the cleanser from leaking and easily securing the object.  FIGS. 9A, 9B  show an upright type dry washing device  60  comprised of a base  62  and a body  64  standing vertically on the base  62 . The plane of the pool  19  is inclined rightward in the drawings relative to verticality. The tank unit  2  is disposed at the center of the pool  19  in the body  64 , as in the first embodiment. The base  28  of the object holder is placed to face the opening of the tank unit  2  and connect with a not-shown direct driving means. 
     An anti-cleanser dispersing unit  68  is the anti-cleanser dispersing element integrated with the frame. It is connected with one side of the base  28  via a hinge  66 . A lock mechanism  70  is disposed on the opposite side of the base  28  to securely connect the base  28  and the anti-cleanser dispersing unit  68 . Referring to  FIGS. 10A, 10B , length-adjustable pins  72  are placed on the side face of the anti-cleanser dispersing unit  68 , and include pin fixtures  74  to lock the pins  72  along the anti-cleanser dispersing element  22 A of the unit  68 . 
     The anti-cleanser dispersing unit is moved in a closed space with a shutter  78  and an outer element for safety reason. The shutter  78  is made of three slidable plates  78   a ,  78   b ,  78   c . With the shutter  78  opened, the opened anti-cleanser dispersing unit  68  can be supported by the hinge  66  as a fulcrum as shown in  FIG. 9A . 
     Next, the operation of the dry washing device  60  is described. 
     First, an operator opens the shutter  78  and releases the lock mechanism  70  of the anti-cleanser dispersing unit  68  to pull down the anti-cleanser dispersing unit  68 . Then, the anti-cleanser dispersing unit  68  is held by the hinge  66  and the opened shutter  78 . The anti-cleanser dispersing element  22 A is placed with the stretch material covering the low repulsive urethane sponge on the top side. The operator places an object  4  in the anti-cleanser dispersing unit so that the surface to be washed comes on the top side. Then, by adjusting the length of the pins  72 , the operator inserts one end of the object  4  below the pins  32 , manually holds it down and pushes it into the anti-cleanser dispersing element  22 A as shown in  FIGS. 10A, 10B . The operator extends the other pins  72  and fixes the positions thereof with the pin fixtures  74 . 
     Thus, the object  4  is held while pressed onto the anti-cleanser dispersing element  22 A. The pins  32  are adjusted so that the object  4  comes below the outer frame of the anti-cleanser dispersing unit  68 . Then, the entire unit  68  is rotated around the hinge as the fulcrum to connect with the base and be fixed with the lock mechanisms. When the device is operated with the shutter  78  closed as shown in  FIG. 9B , the cleanser is accelerated by compressed air to collide with the object and remove attached matter. The anti-cleanser dispersing unit  68  can prevent the cleanser from leaking to outside the washing tank  6  and the pool  19 . By use of the anti-cleanser dispersing element  22 A integrated with the frame, it is possible to improve the cleanser leakage preventing function from that in the above embodiments and reduce the time and labor of the operator. 
     Fifth Embodiment 
     A fifth element is described with reference to  FIGS. 11, 12, 13A, 13B . The features of the present embodiment are in that plural objects are continuously washed, which is extremely difficult with the related art dry washing device since it needs to individually hold objects in the object holder. In the present embodiment a sponge roller is used for an anti-cleanser dispersing element  22 C. It includes a low repulsive urethane sponge roller  80  as a core element and a stretch material  82  as a surface layer to cover the sponge roller  80 . Hereinafter, the urethane sponge roller  80  covered with the stretch material  82  is called sponge roller  80 . Further, a tank unit  84  is a drum type in which the cleanser is blasted off by revolving air flows generated from air intake and suction. The sponge roller  80  has a radius sufficient to close an opening  86  of the tank unit  84  with no object present. 
     The use of a flow palette for the object is described. 
     The sponge roller  80  is rotated to press the surface of a flow palette to close the openings thereof. A loader and unloader  88  to carry palettes  4  are provided before and after the tank unit  84  and sponge roller  80 . The palettes are always held by either of the loader and unloader and moved in parallel. The sponge roller  80  is supported by a rotational shaft  81  and rotated by the movement of the palette  4 . 
     A space  92  is provided at downstream of the tank unit  84 , in which the cleanser remaining on the sponge roller  80  and the palette  4  is blown off by an air nozzle  90  connected with the not-shown compressed air supply unit. The removed cleanser falls around an air inlet  94  of the tank unit  84  via a duct, and is suctioned into the air inlet  94  and blasted off again by the revolving air flows  96 .  FIG. 11  shows an air path limiting element  95  to define the cross sectional shape of the air streams  96  and also to function as a porous separator not to allow the cleanser to pass. While the opening  86  of the tank unit  84  is not closed with the palette, the amount of air inflow from the air inlet  94  is small and the cleanser  5  is absorbed onto the air path limiting element  95  by the air intake from the suction duct  18 . With such a configuration, the amount of the cleanser in the tank unit can be prevented from decreasing by bringing back the cleanser attached to the object from the space  92 . In  FIG. 12  a reference numeral  83  represents sidewalls to prevent the leakage of the cleanser. 
       FIG. 13A, 13B  shows an example of the space in which the cleanser is dispersed. As shown in  FIG. 13B , the horn-shape air nozzles  90  blow compressed air from the side of the palette  4  in a large area of the space  92  to concurrently blow off the cleanser attached to the top and bottom surfaces of the palette  4  in a certain direction. The blow amount from the air nozzles  90  is adjusted by an air valve  91 . Blown off from the top surface of the palette  4 , the cleanser drops on the bottom of the space  92  through a space on one side of the space  92 . The space  92  communicates with the air inlet  94  and suctioning air streams flow to the air inlet  94 . The dropped cleanser is carried with the suctioning air streams, suctioned into the air inlet  94 , and returned to the tank unit. 
     The suctioning air streams are supplied from an exit  100  of the space  92 . At the exit  100  the air streams always flow towards the space  92 . Because of this, the air streams from the nozzles  90  and the cleanser do not leak to outside the tank unit. Additionally provided with a short-curtain like element at the exit  100 , it is possible to further prevent the leakage of the cleanser. Further, a scraper  102  can be provided to scrape off the cleanser attached to the surface of the sponge roller  80  due to static electricity and drop it in the space  92  and collect it in the tank unit. Thus, the dry washing device which can wash plate-like objects continuously is realized. 
     A dry washing device according to a sixth embodiment is described with reference to  14 A to  14 C. A dry washing device  110  or palette washing device comprises a washing unit  112  with an opening to blow off the cleanser by revolving air flows, have it collide with an object from the opening in a part of the revolving area and clean the object, an object holder  114  to hold the object in a washable position, and a three-axis type orthogonal robot  116  to move the washing unit  112  to different positions. The orthogonal robot  116  comprises an X shaft  118  for horizontal movement indicated by the arrow D 1 , a Y shaft  120  for orthogonal movement relative to the drawings, and a Z axis shaft  122  for vertical movement, a base to support these shafts, and a not-shown controller to control the movement of the shafts. The washing unit  112  is attached to the bottom end of the Z shaft  122  via a spring  123 . The object holder  114  includes a support frame  124  for the anti-cleanser dispersing element  22 , a pair of frames  126 ,  128  extending upward from the support frame  124 , and the anti-cleanser dispersing element  22  accommodated in the frames  126 ,  128 . The support frame  124  also works as the base of the orthogonal robot  116 . 
     Pins  32  are fixed to the frame  128  to inhibit the palette from floating up by the repulsive force of the anti-cleanser dispersing element  22 . Longer pins  32  are provided on the other frame  126  to be able to hold palettes of different sizes movably in the direction indicated by the arrow H (in  FIG. 14C ). In the present embodiment the anti-cleanser dispersing element  22  is configured to cover the object  4  from below while in the above embodiments it covers the object  4  from above. 
     The washing unit  112  is connected with a suction hose  130  which is connected with a not-shown suction unit. The washing unit  112  is configured to generate revolving air flows at a high speed inside to circulate the cleanser, and allow the cleanser to collide with the object  4  and wash it in an opening  112   a  in the revolving area. When the opening  112   a  is closed with the object  4  while the washing unit  112  is being air-suctioned by the suction unit, outside air is flowed thereinto at a high speed from an inlet  112   b , producing revolving air flows around a cylindrical element  112   c  at the center of the unit  112  as a rotational axis. Thereby, the cleanser is dispersed in the housing of the washing unit  112 . 
     A not-shown porous element is provided between the connecting portion with the suction unit and the inside of the housing. The holes of this element are of a size enough to allow matters to be removed to pass therethrough but to prevent the cleanser from passing therethrough. When the inside of the housing is negatively pressurized by suction, the cleanser is absorbed onto the porous element until the revolving air flows are produced. Therefore, the cleanser is held inside the housing and does not leak to outside even with the opening  112   a  separated from the object  4 . The washing unit  112  uses a housing disclosed in Japanese Patent Application Publication No. 2012-050973 filed by the applicant of the present invention. The washing unit  112  is enclosed in a rectangular case and a spring  123  is fixed to the case, thereby facilitating the connection of the Z shaft  122  and the unit  112  via the spring  123 . 
     A seal element  132  with a smooth surface made from a flexible material is provided around the opening  112   a  of the washing unit  112 . This helps the opening  112   a  closely attach to the palette  4  in accordance with the unevenness in the surface thereof. The seal element  132  can be a brush with nylon hairs or a sponge covered with a felt material. 
     The operation of the dry washing device  110  is described. 
     First, an operator provides a proper amount of cleanser in the housing of the washing unit  112  by suctioning it from the opening  112   a  or pouring it from the air inlet  112   b . Next, the operator sets the palette  4  on the anti-cleanser dispersing element  22 , and inserts one end of the palette  4  below the fixed pins  32  and pushes the other end to hold it down by manipulating the movable pins  32 . Once the palette  4  is secured, the operator makes sure that all the openings of the palette are enclosed with the anti-cleanser dispersing element  22  and inputs an operation start signal to the not-shown controller to operate the suction unit. The controller then operates the X and Y shafts of the orthogonal robot  116  to move the washing unit  112  to the corner (washing home position) of the palette  4 . 
     Then, the controller operates the Z axis of the orthogonal robot  116  to lower the washing unit  112  and press it down onto the palette until the spring  123  is deflected at a certain amount. By this pressure, the seal element  132  is deformed to closely attach to the palette and close the opening  112   a  of the washing unit  112 , thereby decreasing the pressure in the washing unit  112  by suction and increasing the amount of air streams flowing thereinto from the air inlet  112   b . Thus, the cleanser is dispersed by revolving air flows in the washing unit  112  and collides with the palette  4  closely attaching to the opening  112   a . Thereby, the fluxes on the palette surfaces can be quickly removed. 
     Next, the controller moves in parallel the washing unit  112  contacting the palette  4  as indicated by the broken line in  FIG. 14C . It can move it in parallel by the spring  123  along the Z shaft while pressing down the palette irrespective of the unevenness or undulation in the palette surface. By the parallel movement, the washing unit  112  can wash the area larger than the opening  112   a . Moreover, the deformation of the anti-cleanser dispersing element  22  can prevent the occurrence of a gap at the end of the palette or around the opening so that the entire palette surface can be washed without the leakage of the cleanser from the opening of the washing unit. The movement of the washing unit  112  is programmed in advance. Alternatively, the washing unit can be discontinuously moved since the cleanser does not leak to outside due to the cleanser dispersion and absorption effect even if the washing unit is separated from the object (disclosed in Japanese Patent Application Publication No. 2012-50973). 
     It is preferable to move the washing unit in line with the shape of the palette if the palette is made of a frame only or a different-shape palette is used. By optimally moving the washing unit, the washing can be completed in a shorter time and the consumption of cleanser can be reduced. 
     In the present embodiment the orthogonal robot is used for the moving element for the washing unit. Alternatively, a horizontal or vertical multi-joint robot can be used. 
     Further, in the present embodiment the palette is disposed with the surface to be washed on the top side. However, the surface to be washed can face sideways or downward as long as the opening of the palette as an object can be closed with the anti-cleanser dispersing element. It can be washed by changing the movement of the washing unit. 
     Although the present invention has been described in terms of exemplary embodiments, it is not limited thereto. It should be appreciated that variations or modifications may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims.