Technical Field The present invention relates to an apparatus for washing and drying a disk-shaped workpiece such as a magnetic disk substrate made of aluminum and its alloy, a method for washing and drying a disk-shaped workpiece, a method for manufacturing a magnetic disk substrate, and a magnetic disk substrate.

Background Art An apparatus for washing and drying a disk-shaped workpiece as a related art will be explained with referring to Fig. 4 only for the purpose of helping the understanding of the present invention. Accordingly, it should not be understood that the apparatus constitutes an applicant's admitted prior art.

The apparatus includes a washing unit 110, a drying unit 120 and an unloading unit 130 arranged in this order. Each unit includes an independent inner space and is isolated from the exterior by a respective covering member 111,121 and 131.

The washing unit 110 is a unit for washing workpieces W. In this unit, a plurality of machined disk-shaped workpieces W, which are conveyed into this unit by aworkpiece feeder (now shown) through a carrying-in window 112 provided in an upper part of the covering member 111, are held by a turntable. Resin brushes rub both sides of the workpiece W while supplying purified water to thereby wash it.

The drying unit 120 is a unit for drying disk-shaped workpieces W, and is isolated from the washing unit 110 by a partitioning wall.

In this drying unit 120, washed workpieces W, which are transferred from the washing unit 110 through a carrying-in window provided in an upper part of the partitioning wall by a workpiece transferring apparatus (not shown), are held by a turntable to be dried while being rotated.

Each of the front cover members llla and 121a of the washing unit 110 and the drying unit 120 is made of transparent acrylic resin so that the inside thereof can be visually confirmed through the front cover members Illa and 121a.

The unloading unit 130 is a unit for temporarily storing the dried workpieces W taken out through a workpiece transferring portion 132 communicating the drying unit 120 with the unloading

unit 130 so that the workpieces W can be transferred to the following processing.

By the way, in the drying unit 120, the washed workpiece W held by the turntable is spun about the self-axis thereof at a predetermined position on the turntable to disperse the moisture adhered thereon during the washing process while the turntable rotates by a predetermined angle. Thus, the washed workpiece W is dried.

As the workpiece spins as mentioned above, however, not only moisture but also minute granular objects such as dust (hereinafter also referred to as"particles") on the workpiece W will be also dispersed. As a result, the particles stagnates in the drying unit 120 and re-adheres to the dried workpiece W. In cases where the <BR> <BR> <BR> <BR> <BR> workpiece W is supposed to be used as a magnetic disk that is required to have high quality, since it is difficult to discriminate between such particles adhered to the workpiece W and defects of the workpiece W, the workpiece W to which particles are adhered will be treated as inferior goods.

To cope with this problem, it is considered to provide a particle-removing air filer 122, called HEPA filter (High <BR> <BR> <BR> <BR> <BR> Efficiency Particulate Air Filter), at an upper covering member 121b of the drying unit 120 for supplying purified air into the drying unit 120 as shown in the arrow A through the air filter 122 so that the inside of the drying unit 120 can be maintained to be clean.

In the aforementioned apparatus, however, the purified air

supplied into the drying unit 120 flows not only toward the washing unit 110 as shown in the arrow B but also toward the unloading unit 130 as shown in the arrow C. Accordingly, the particles dispersed in the drying unit 120 during the drying process of the workpiece W may be carried into the unloading unit 130, which in turn may cause an adhesion of particles to the workpiece W stored in the unloading unit 130. Furthermore, the flow of the purified air supplied from the upper part of the drying unit 120 tends to be interrupted by interior parts such as a turntable in the drying unit 120, and therefore the purified air is hardly introduced to the inner lower portion of the drying unit 120, which causes stagnation of air containing particles.

In order to prevent the air flow from the drying unit 120 to the unloading unit 130 and eliminate the air stagnation in the lower portion of the drying unit 120, it is considered to provide a ventilation duct at the lower portion of the drying unit 120 for local ventilation, or to supply purified air into the unloading unit 130 as shown by the arrow D through the HEPA filer 133 provided on the upper covering member 131a of the unloading unit 130. However, it is considered not enough to solve the aforementioned problems.

Disclosure of Invention It is an object of the present invention to provide an apparatus and a method for washing and drying a disk-shaped workpiece capable of preventing re-adhesion of particles to the

washed and dried workpiece in an unloading unit.

It is another object of the present invention to provide a method for manufacturing an aluminum magnetic disk substrate having a clean surface with little particle, and also to provide such an aluminum magnetic disk substrate.

According to the first aspect of the present invention, an apparatus for washing and drying a disk-shaped workpiece, includes: a washing unit for washing the disk-shaped workpiece, the washing unit having an inner space covered by a covering member; a drying unit for drying the workpiece washed in the washing unit, the drying unit having an inner space covered by a covering member, the inner space of the drying unit being partially or entirely communicated with the inner space of the washing unit ; an unloading unit into which the dried workpiece is transferred from the drying unit, the unloading unit being connected to the drying unit ; a purified gas supplying portion for supplying purified gas into the drying unit; an opening provided at at least a part of the covering member of the drying unit for communicating an inside of the drying unit with an outside thereof; and an opening provided at at least a part of the covering member of the washing unit for communicating an inside of the washing unit with an outside thereof.

In this apparatus for washing and drying a disk-shaped

workpiece, since the opening is provided at at least a part of the covering member of the drying unit so that the inside of the drying unit is communicated with an outside thereof, the purified gas supplied into the drying unit is discharged out of the apparatus through the opening of the covering member of the drying unit.

Furthermore, since the opening is provided at at least a part of the covering member of the washing unit so that the inside of the washing unit is communicated with the outside thereof, it becomes easy for the gas in the drying unit to flow into the washing unit, causing a discharge of the gas through the opening of the washing unit. Accordingly, it is prevented that the gas in the drying unit flows into the unloading unit.

According to the second aspect of the present invention, an apparatus for washing and drying a disk-shaped workpiece, includes: a washing unit for washing the disk-shaped workpiece; a drying unit for drying the workpiece washed in the washing unit, the drying unit being connected to the washing unit; an unloading unit into which the workpiece dried in the drying unit is transferred from the drying unit through a workpiece transferring passage, the unloading unit being connected to the drying unit via the workpiece transferring passage; and a purified gas supplying portion for supplying purified gas into the workpiece transferring passage to prevent a gas flow from the drying unit to the unloading unit.

In this apparatus, the gas supplied into the work transferring

passage between the drying unit and the unloading unit prevents the gas flow from the drying unit to the unloading unit. This decreases a risk that the gas containing the particles in the drying unit flows into the unloading unit and the particles re-adheres to the workpieces in the unloading unit.

According to the third aspect of the present invention, an apparatus for washing and drying a disk-shaped workpiece, includes: a washing unit for washing the disk-shaped workpiece, the washing unit having an inner space covered by a covering member; a drying unit for drying the workpiece washed in the washing unit, the drying unit having an inner space covered by a covering member, the inner space of the drying unit being partially or entirely communicated with the inner space of the washing unit; an unloading unit into which the workpiece dried in the drying unit is transferred from the drying unit through a workpiece transferring passage, the unloading unit being connected to the drying unit via the workpiece transferring passage; a purified gas supplying portion for supplying purified gas into the drying unit; an opening provided at at least a part of the covering member of the drying unit for communicating an inside of the drying unit with an outside thereof; an opening provided at at least a part of the covering member of the washing unit for communicating an inside of the washing unit with an outside thereof; and

a purified gas supplying portion for supplying purified gas into the workpiece transferring passage located between the drying unit and the unloading unit to prevent a gas flow from the drying unit to the unloading unit.

In this apparatus, the opening is provided at at least a part of the covering member of the drying unit so that the inside of the drying unit is communicated with the outside thereof, the purified gas supplied into the drying unit is discharged out of the apparatus through the opening formed in the covering member of the drying unit.

Furthermore, since the opening is provided at at least a part of the covering member of the washing unit so that the inside of the washing unit is communicated with the outside thereof, it becomes easy for the gas in the drying unit to flow into the washing unit, causing a discharge of the gas through the opening of the washing unit. Furthermore, the gas supplied into the work transferring passage between the drying unit and the unloading unit prevents the gas flow from the drying unit to the unloading unit. This decreases a risk that the gas containing the particles in the drying unit flows into the unloading unit and the particles re-adheres to the workpieces in the unloading unit.

According to the fourth aspect of the present invention, a method for washing and drying a disk-shaped workpiece, includes: washing a disk-shaped workpiece in a washing unit; drying the washed workpiece in a drying unit having an inner space partially or entirely communicated with an inner space of the

washing unit; and transferring the dried workpiece from the drying unit to an unloading unit, wherein the drying of the workpiece in the drying unit is performed while supplying purified gas into the inner space of the drying unit and discharging the purified gas in the inner space of the drying unit out of the apparatus through at least a part of a covering member covering the inner space of the drying unit, and wherein the washing of the workpiece in the washing unit is performed while discharging the purified gas flowed into the washing unit from the drying unit out of the apparatus through at least a part of the covering member covering the inner space of the washing unit.

In this washing method, the purified gas supplied into the drying unit is discharged out of the apparatus through the opening of the covering member of the drying unit. Furthermore, it becomes easy for the gas to flow into the washing unit, causing a discharge of the gas through the opening of the washing unit. Accordingly, it is prevented that the gas in the drying unit flows into the unloading unit.

According to the fifth aspect of the present invention, a method for washing and drying a disk-shaped workpiece, includes the steps of: washing a disk-shaped workpiece in a washing unit; drying the washed workpiece in a drying unit connected to the

washing unit; and transferring the dried workpiece from the drying unit to the unloading unit through a work transferring passage connected to the drying unit, wherein purified gas is supplied into the workpiece transferring passage to prevent a gas flow from the drying unit to the unloading unit.

In this method, the purified gas supplied into the work transferring passage between the drying unit and the unloading unit prevents the gas flow from the drying unit to the unloading unit.

This decreases a risk that the gas containing the particles in the drying unit flows into the unloading unit and the particles re- adheres to the workpieces in the unloading unit.

According to the sixth aspect of the present invention, a method for washing and drying a disk-shaped workpiece, includes the steps of: washing a disk-shaped workpiece in a washing unit; drying the washed workpiece in a drying unit having an inner space partially or entirely communicated with an inner space of the washing unit; and transferring the dried workpiece from the drying unit to the unloading unit connected to the drying unit through a workpiece transferring passage, wherein the drying of the workpiece in the drying unit is performed while supplying purified gas into the inner space of the

drying unit and discharging the purified gas in the inner space of the drying unit out of the apparatus through at least a part of a covering member covering the inner space of the drying unit, wherein the washing of the workpiece in the washing unit is performed while discharging the purified gas flowed into the washing unit from the drying unit out of the apparatus through at least a part of the covering member covering the inner space of the washing unit, and wherein purified gas is supplied into the workpiece transferring passage to prevent a gas flow from the drying unit to the unloading unit.

In this method, the purified gas supplied into the drying unit is discharged out of the apparatus through the opening of the covering member of the drying unit. Furthermore, it becomes easy for the gas in the drying unit to flow into the washing unit, causing a discharge of the gas through the open portion of the washing unit.

Furthermore, the purified gas supplied into the work transferring passage between the drying unit and the unloading unit prevents a gas flow from the drying unit to the unloading unit.

According to the seventh aspect of the present invention, a method for manufacturing a washed and dried magnetic disk substrate, includes the steps of: washing a disk-shaped workpiece in a washing unit; drying the washed workpiece in a drying unit having an inner space partially or entirely communicated with an inner space of the

washing unit; and transferring the dried workpiece from the drying unit to an unloading unit, wherein the drying of the workpiece in the drying unit is performed while supplying purified gas into the inner space of the drying unit and discharging the purified gas in the inner space of the drying unit out of the apparatus through at least a part of a covering member covering the inner space of the drying unit, and wherein the washing of the workpiece in the washing unit is performed while discharging the purified gas flowed into the washing unit from the drying unit out of the apparatus through at least a part of the covering member covering the inner space of the washing unit.

According to this method for manufacturing a magnetic disk substrate, the purified gas supplied into the drying unit is discharged out of the apparatus through the opening of the covering member of the drying unit. Furthermore, it becomes easy for the gas in the drying unit to flow into the washing unit, causing a discharge of the gas through the opening of the washing unit.

Accordingly, it is prevented that the gas in the drying unit flows into the unloading unit, which enables a manufacturing of an aluminum magnetic disk substrate with little adhesion of particles.

According to the eighth aspect of the present invention, a method for manufacturing a washed and dried magnetic disk substrate includes the steps of:

washing a disk-shaped workpiece in a washing unit; drying the washed workpiece in a drying unit having an inner space partially or entirely communicated with an inner space of the washing unit; and transferring the dried workpiece from the drying unit to an unloading unit connected to the drying unit through a workpiece transferring passage, wherein purified gas is supplied into the workpiece transferring passage to prevent a gas flow from the drying unit to the unloading unit.

According to this method for manufacturing the magnetic disk substrate, the purified gas supplied into the work transferring passage between the drying unit and the unloading unit prevents the gas flow from the drying unit to the unloading unit. This decreases a risk that the gas containing the particles in the drying unit flows into the unloading unit and the particles re-adheres to the workpieces in the unloading unit. Accordingly, an aluminum magnetic disk substrate with little adhesion of particles can be manufactured.

According to the ninth aspect of the present invention, a method for manufacturing a washed and dried magnetic disk substrate includes the steps of: washing a disk-shaped workpiece in a washing unit; drying the washed workpiece in a drying unit having an inner space partially or entirely communicated with an inner space of the

washing unit; and transferring the dried workpiece from the drying unit to the unloading unit through a work transferring passage connected to the drying unit, wherein the drying of the work in the drying unit is performed while supplying purified gas into the inner space of the drying unit and discharging the purified gas in the inner space of the drying unit out of the apparatus through at least a part of a covering member covering the inner space of the drying unit, wherein the washing of the work in the washing unit is performed while discharging the purified gas flowed into the washing unit from the drying unit out of the apparatus through at least a part of the covering member covering the inner space of the washing unit, and wherein purified gas is supplied into the workpiece transferring passage to prevent a gas flow from the drying unit to the unloading unit.

According to the method for manufacturing a magnetic disk substrate, the purified gas supplied into the drying unit is discharged out of the apparatus through the opening of the covering member of the drying unit. Furthermore, it becomes easy for the gas in the drying unit to flow into the washing unit, causing a discharge of the gas through the opening of the washing unit.

Furthermore, the purified gas supplied into the work transferring passage between the drying unit and the unloading unit prevents a

gas flow from the drying unit to the unloading unit. Accordingly, an aluminum magnetic disc substrate with little adhesion of particles can be manufactured.

According to the tenth aspect of the present invention, in a magnetic disk substrate to which washing in a washing unit, drying in a drying unit having an inner space partially or entirely communicated with an inner space of the washing unit and transferring from the drying unit to an unloading unit are performed in this order, the drying in the drying unit is performed while supplying purified gas into the inner space of the drying unit and discharging the purified gas in the inner space of the drying unit out of the apparatus through at least a part of a covering member covering the inner space of the drying unit, and the washing in the washing unit is performed while discharging the purified gas flowed into the washing unit from the drying unit out of the apparatus through at least a part of the covering member covering the inner space of the washing unit.

In this magnetic disk substrate, since it is prevented for the gas in the drying unit to flow into the unloading unit, an aluminum magnetic disk substrate with little adhesion of particles can be obtained.

According to the eleventh aspect of the present invention, in a magnetic disk substrate to which washing in a washing unit, drying in a drying unit having an inner space partially or entirely

communicated with an inner space of the washing unit and transferring from the drying unit to an unloading unit are performed in this order, the transferring from the drying unit to the unloading unit is performed through a workpiece transferring passage in which a gas flow from the drying unit to the unloading unit is prevented by supplying purified gas into the unloading unit.

In this magnetic disk substrate, since it is prevented for the gas in the drying unit to flow into the unloading unit, an aluminum magnetic disk substrate with little adhesion of particles can be obtained.

According to the twelfth aspect of the present invention, in a magnetic disk substrate to which washing in a washing unit, drying in a drying unit having an inner space partially or entirely communicated with an inner space of the washing unit and transferring from the drying unit to the unloading unit are performed in this order, the drying in the drying unit is performed while supplying purified gas into the inner space of the drying unit and discharging the purified gas in the inner space of the drying unit out of the apparatus through at least a part of a covering member covering the inner space of the drying unit, the washing in the washing unit is performed while discharging the purified gas flowed into the washing unit from the drying unit out of the apparatus through at least a part of the covering member

covering the inner space of the washing unit, and the transferring from the drying unit to the unloading unit is performed through a workpiece transferring passage in which a gas flow from the drying unit to the unloading unit is prevented by supplying purified gas into the unloading unit.

In the magnetic disk substrate, since it is prevented for the gas in the drying unit to flow into the unloading unit, an aluminum magnetic disk substrate with little adhesion of particles can be obtained.

Other objects and advantages of the present invention will be apparent from the following preferred embodiments with referring the attached drawings.

Brief Description of Drawings Fig. 1 is a perspective view showing a schematic structure of an apparatus for washing and drying a disk-shaped workpiece according to an embodiment of the present invention.

Fig. 2 is a front view showing a schematic structure of the drying unit of the apparatus shown in Fig. 1.

Fig. 3 is a perspective view showing a schematic structure of an apparatus for washing and drying a disk-shaped workpiece according to another embodiments of the present invention.

Fig. 4 is a perspective view showing a schematic structure of an apparatus for washing and drying a disk-shaped workpiece as a related art of the present invention.

Best Mode for Carrying Out the Invention Fig. 1 shows an apparatus for washing and drying a disk-shaped workpiece according to the first embodiment of the present invention.

In this embodiment, an aluminum (including its alloy) magnetic disk substrate will be exemplified as a disk-shaped workpiece.

In Fig. 1, the reference numeral 1 denotes an apparatus for washing and drying a disk-shaped workpiece. This apparatus 1 is equipped with a washing unit 10, a drying unit 20 and an unloading unit 30.

Each unit has an inner space covered with a respective covering member 11,21 and 31. The washing unit 10 and the drying unit 20 are divided by a partitioning wall (not shown).

At the external side of the washing unit 10, a workpiece supplying apparatus (not shown) is provided. This workpiece supplying apparatus supplies machined workpieces W into the washing unit 10 through a workpiece carrying-in aperture 12 provided in the covering member 11 of the washing unit 10.

The washing unit 10 is a unit for washing the workpieces W, and is equipped with a turntable for holding a plurality of workpieces W. Then, the carried-in workpieces W are held by the turntable 23 at predetermined positions, respectively. Then, the held workpieces W are moved in a circumferential direction of the turntable 23 in accordance with the rotation of the turntable 23. <BR> <BR> <BR> <P>During the rotation of the turntable 23, both sides of each workpiece

W are rubbed and washed by resin brushes (not shown) while supplying purified water.

Almost the entire front side portion (as seen from the front side of Fig. 1) of the covering member 11 of the washing unit 10 is formed by a metal mesh member. This front side portion constitutes an opening lla communicating an inside of the washing unit 10 with the outside of the apparatus 1. As for the mesh member, a 2.5 mm-square-mesh stainless steel mesh member may be preferably used. However, the mesh member is not limited to this.

At the upper portion of the partitioning wall partitioning the washing unit 10 and the drying unit 20, a work transferring opening (not shown) is provided. Furthermore, a workpiece transferring apparatus (not shown) is disposed so that the workpiece W can pass through the aforementioned work transferring opening.

Thus, the workpiece W washed in the washing unit 10 is taken out from the predetermined position of the turntable 23 by the workpiece transferring apparatus, and is transferred to the drying unit 20.

The drying unit 20 is a unit for drying the washed workpiece W, and is equipped with a vertical type turntable 23 capable of holding a plurality of workpieces W as shown in Fig. 2. This turntable 23 is equipped with six workpiece holding portions 24 arranged in the peripheral direction thereof. At the upper portion of the turntable 23, a workpiece taking-in/taking-out stage ST1 <BR> <BR> <BR> <BR> <BR> is provided. When the turntable 23 makes one revolution clockwisely or counterclockwisely as shown in the arrow in Fig. 2, the workpiece

W is taken out from the workpiece taking-in/taking-out stage ST1 sequentially. During the revolution of the turntable 23, the workpiece W is dried.

Concretely, in the drying unit 20, the aforementioned workpiece taking-in/taking-out stage ST1, a spin drying stage ST2 and an after-spin drying stage ST3 are arranged in the revolution direction of the turntable 23. At the spin drying stage ST2, the workpiece W held by the workpiece holding portion 24 is spun about the self-axis thereof in the washing unit 20 to disperse moisture, dust or the like adhered to the workpiece W, to thereby be dried. <BR> <BR> <BR> <BR> <BR> <P>At the after-spin drying stage ST3, the workpiece W is rotated slowly about the self-axis thereof. As will be understood from the above, since the workpiece taking-in/taking-out stage ST1, the spin drying stage ST2 and the after-spin drying stage ST3 are arranged in the same space of the drying unit 20, there is a possibility that particles dispersed when workpieces W are spun in the spin drying stage ST2 re-adheres to the washed and dried workpieces W.

Accordingly, in this embodiment, HEPA filters 22 (High Efficiency Particulate Air Filter) constituting purified gas (air) supplying portions are provided to the upper covering member 21b of the drying unit 20, and another HEPA filter 25 is also provided to the lower portion of the front covering member 21a of the drying unit 20 so that purified air can be supplied toward the workpieces W held by the turntable 23. Thus, as shown in the arrows A and E, purified air is supplied into the drying unit 20 from the upper and

lower portions thereof. Especially, in this embodiment, since the purified air is also supplied through the lower HEPA filter 25, purified air is supplied into the entire inner space of the drying unit 20 including the lower portion thereof.

The front portion 2 la of the covering member 21 of the drying unit 20 is made of transparent acrylic resin, and the upper portion thereof is made of metal mesh member which constitutes an opening 21c for communicating the inner space of the drying unit 20 with the outer space thereof. As for the mesh member, a 2.5 mm- square-mesh stainless steel mesh member may be preferably used.

However, the mesh member is not limited to this. Although the pressure in the drying unit 20 tends to rise because the purified air is supplied into the drying unit 20 from the upper and lower sides thereof as mentioned above, since the air will be discharged out of the apparatus through the opening 21c as shown by the arrow J in Fig. 1, the pressure rise in the drying unit 20 can be prevented.

Furthermore, since a large opening lla is also provided in the covering member 11 of the washing unit 10, as shown by the arrow B in Fig. 1, a part of the air in the drying unit 20 flows into the washing unit 10, and then, as shown by the arrow K, is discharged out of the apparatus through the opening lla.

Thus, the air in the drying unit 20 is positively discharged <BR> <BR> <BR> <BR> <BR> through the openings 21c and 11a of the drying unit 20 and the washing unit 10, and therefore the particles in the drying unit 20 is discharged out of the apparatus together with the air. In contrast,

the air flow toward the unloading unit 30 is controlled, which in turn decreases the possibility that the particles in the drying unit 20 travels to the unloading unit 30 and adheres to the workpieces W therein.

In addition, another ventilating apparatus may be provided at the rear side of the turntable 23 in the lower portion of the drying unit 20.

The aforementioned unloading unit 30 is a portion which stores the dried workpieces W taken out through a workpiece transferring portion 32 communicating the drying unit 20 with the unloading unit 30 so that the workpiece W is subjected to the following processing.

The unloading unit 30 is provided with a workpiece transferring portion 32 at the drying unit 20 side. Through this workpiece transferring portion 32, dried workpieces W are transferred into the unloading unit 30 by a transferring apparatus (not shown).

The unloading unit 30 is provided with a HEPA filter 33 as a purified gas supplying portion at the upper surface 31a of the covering member 31. Through this filter 33, as shown by the arrow D, purified air is supplied into the unloading unit 30 to keep the inside of the unloading unit 30 clean.

Next, the operation of the apparatus shown in Fig. 1 for washing and drying a disk-shaped workpiece will be explained.

When a workpiece W is supplied to the washing unit 10, the supplied workpiece W is held by the turntable 23, and predetermined washing will be carried out. The washed workpiece W is transferred

to the drying unit 20 and held by the turntable 23 of the drying unit 20. The workpiece W is spun about its self-axis thereof during one revolution of the turntable 23 to remove moisture, dust and the like adhered to the workpiece W.

The dust or the like removed from the workpiece W disperses and floats in the space of the drying unit 20 as particles. However, since purified air is being supplied from the upper and lower sides of the drying unit 20 and the opening 21c is provided in the front covering member 21a of the drying unit 20, the particles floating in the drying unit 20 are discharged out of the apparatus through the opening 21c together with the purified air.

In addition, since the opening lla is also provided in the front covering member of the washing unit 10, a part of air in the drying unit 20 flows into the washing unit 10 through the workpiece transferring aperture of the partitioning wall as shown in the arrow B and then is discharged out of the apparatus from the opening lla of the washing unit 10.

Thus, the air in the drying unit 20 flows out of the apparatus through the opening 21c of the drying unit 20 and the opening lla of the washing unit 10. As a result, the generation of the air flow from the drying unit 20 to the unloading unit 30 is restrained.

Rather, the purified air supplied to the unloading unit 30 through the HEPA filter 33 flows toward the drying unit 20 as shown by the arrow F because the air is pulled by the air flow which is being discharged through both the openings lla and 21c and the pressure

in the unloading unit 30 increases. This further decreases the risk that the particles came from the drying unit 20 re-adheres to the workpiece W stored in the unloading unit 30.

Fig. 3 shows the second embodiment of the present invention.

In this washing and drying apparatus 1 according to this embodiment, as shown by the arrow G, purified air is supplied into the workpiece transferring portion 32 communicating the drying unit 20 with the unloading unit 30 through a HEPA filter 35 constituting a purified gas supplying portion. Since the other structure is the same as that of the first embodiment shown in Figs. 1 and 2, the explanation will be omitted.

The supplying of the purified air into the workpiece transferring portion 32 creates an air curtain which intercepts the work transferring passage by the purified air, thereby effectively intercepting the air movement from the drying unit 20 to the unloading unit 30. Accordingly, it is more assuredly prevented that the air containing particles in the drying unit 20 flows into the unloading unit 30.

In the second embodiment shown in Fig. 3, in addition to the first embodiment, an air curtain is added in the workpiece transferring portion 32 located between the drying unit 20 and the unloading unit 30. However, in the present invention, only the air curtain formed by supplying purified air may be formed in the workpiece transferring portion 32 located between the drying unit 20 and the unloading unit 30 without forming the openings lla and/or

21c in the washing unit 10 and/or the drying unit 20 and without supplying purified air from the lower portion of the drying unit 20. In this case, it is also possible to prevent that the air in the drying unit 20 flows into the unloading unit 30.

Furthermore, the gas existing in the drying unit 20 and the unloading unit 30 and/or the gas to be supplied through the filter may not be limited to air but may be, for example, inert gas.

Furthermore, although the openings lla and 21c provided in the washing unit 10 and the drying unit 20 are formed by a mesh member respectively, the opening may be a perfect opening in which no covering member exists.

Example By using the washing and drying apparatus according to the first embodiment shown in Fig. 1 and the washing and drying apparatus according to the second embodiment shown in Fig. 3, the workpieces as magnetic disk substrates were washed in the washing unit 10, and then dried by the drying unit 20. Thereafter, the dried workpieces are taken out from the drying unit 20, and the number of particles of 0.3 Am grain size and 0.5Mm grain size in each part at the time of taking out from the drying unit 20 and storing them in the unloading unit 30 were measured. The measurements were performed in the drying unit (X portion in Figs. 1 and 3), in the workpiece transferring portion located between the drying unit and the unloading unit (Y portion in Figs. 1 and 3) and in the unloading unit (Z portion in Figs. 1 and 3) three times at different timings

respectively, and each average value was calculated.

On the other hand, as comparative examples, by using a washing and drying apparatus as shown in Fig. 4 in which no opening is formed in the covering members of the washing unit 10 and the drying unit 20 and no purified air is supplied from the lower portion of the drying unit 20 and into the workpiece transferring portion 32 between the drying unit 10 and the unloading unit 30, the number of the aforementioned particles were measured three times at the same portions as mentioned above at different timings.

The measured results are shown in Table 1.

Table 1 Number of particles (pieces/m3) Diameter Portion X Diameter Portion Y Diameter Portion Z of (in the drying unit) (in the workpiece (in the unloading unit) Apparatus particle transferring passage) (µm) 1st 2nd 3rd Average 1st 2nd 3rd Average 1st 2nd 3rd Average time time time time time time time time time Apparatus 1 0.3 353 212 282 282 2118 1906 1377 1800 2083 1765 1730 1860 (First 0.5 71 35 35 46 565 388 388 448 565 494 530 530 embodiment) Apparatus 2 0.3 177 212 318 236 671 847 741 752 671 635 883 731 (Second 0.5 35 35 35 35 71 212 177 152 106 177 318 201 embodiment) Comparative 0.3 2895 1659 3389 2648 6248 6319 5683 6082 6673 5330 5825 5941 Apparatus 0.5 847 388 847 695 1059 1376 1024 1154 1730 1236 1271 1412

As will be understood from the result shown in table 1, in the unloading unit 30 of the comparative apparatus, the average values of the number of particles having the grain size of 0.3 <BR> <BR> <BR> <BR> <BR> am and 0. 5/tm were 5, 941 pieces/M3 and 1, 412 pieces/M3 respectively.

To the contrary, in the first embodiment in which no air curtain was formed in the workpiece transferring portion 32, the average values of the number of particles having the grain size of 0.3 am and 0.5Am were 1,860 pieces/m3and 530 pieces/m3, respectively, and in the second embodiment in which the air curtain was formed in the workpiece transferring portion 32, the average values of the number of particles having the grain size of 0.3Am and 0.5Rm were 731 pieces/m3 and 201 pieces/m3, respectively.

In the drying unit 20 of the comparative apparatus, the average values of the number of particles having the grain size of 0.3 tt m and 0.5Am were 2,648 pieces/m3and 695 pieces/m3, respectively.

To the contrary, in the first embodiment in which no air curtain was formed in the workpiece transferring portion 32, the average values of the number of particles having the grain size of 0.3 am and 0.5Am were 282 pieces/m3 and 46 pieces/m3, respectively, and in the second embodiment in which the air curtain was formed in the workpiece transferring portion 32, the average values of the number of particles having the grain size of 0.3Am and 0.5Am were 236 pieces/m3 and 35 pieces/m3, respectively.

From the results shown in Table 1, according to this invention, it is understood that the number of particles in the drying unit

20 and the unloading unit 30 can be decreased, and therefore the re-adhesion of particles to the dried workpiece can be prevented.

Furthermore, in cases where an air curtain is formed in the workpiece transferring portion 32, it is understood that the effect for preventing particles from being introduced into the unloading unit 30 is more effective as compared with the cases where no air curtain is formed.

Industrial Applicability As mentioned above, since the apparatus for washing and drying a disk-shaped workpiece according to the present invention, the method for washing and drying a disk-shaped workpiece, the method for manufacturing a magnetic disk substrate and the magnetic disk substrate can prevent re-adhesion of particles to the workpiece in an unloading unit, they are suitably used as an apparatus for washing and drying, for example, an aluminum magnetic disk and a method for washing and drying the same.

This application claims priority to Japanese Patent Application No. 2001-45284 filed on February 21,2001, the disclosure of which is incorporated by reference in its entirety.

The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intent, in the use of such terms and expressions, of excluding any of the equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.