JP5388809B2 - Hydrostatic gas bearing spindle - Google Patents

Description

  The present invention relates to a high-precision hydrostatic gas bearing spindle used in the manufacturing process, inspection process and the like of magnetic disks and optical disks.

The hydrostatic gas bearing spindle supports the main shaft in a non-contact manner by the hydrostatic gas bearing, and therefore has high rotational accuracy and is used for a work spindle or a tool spindle of a precision processing machine or a precision inspection apparatus. In such a spindle, in order to prevent intrusion of disturbance and improve controllability, the motor rotor is often directly attached to the main shaft without using a belt or the like.
Especially in applications such as manufacturing and inspection processes for magnetic disks and optical disks, it is necessary to write data signals at high density in order to improve the recording density of the disk, and high positioning accuracy between the disk and the recording unit or reproducing head, etc. In addition, high rotational accuracy of the spindle is required. In a static pressure gas bearing spindle used for such applications, feedback control is often performed by directly attaching a synchronous servo motor using a permanent magnet to a motor rotor and a rotary encoder to a main shaft. For example, as the synchronous servo motor, hydrostatic gas bearing spindle using servo motors and coreless servo motor with cores are known (Patent Document 1).

JP 2006-84279 A

  In the disk master manufacturing apparatus using the static pressure gas bearing spindle, the disk master is mounted on a rotary table attached to the spindle main end. Then, with the disc master rotated, the resist applied to the master surface is irradiated with a converged electron beam or a focused laser beam, and the beam is relatively parallel to the main surface of the rotary table. By moving, the recorded information is exposed or drawn on the disc master.

However, in such a disk master manufacturing apparatus, when the heat generated by the spindle motor or the like is transmitted to the disk master through the main shaft, the reaction speed of the resist becomes unstable and uneven reaction occurs. Further, when the main shaft expands due to heat, a relative position change occurs between the beam irradiation portion and the master surface. As a result, recording of highly accurate information is hindered.
For this reason, the static pressure gas bearing spindle used in the disk master manufacturing apparatus described above is required to reduce heat generation and heat transfer in addition to high rotational accuracy.

  An object of the present invention is to provide a hydrostatic gas bearing spindle capable of effectively reducing heat generation and heat transfer.

A hydrostatic gas bearing spindle according to a first configuration of the present invention includes a hydrostatic gas bearing that rotatably supports a main shaft, and a motor that rotates a main shaft by fixing a motor rotor to the main shaft. A hydrostatic gas bearing spindle in which one end portion of the main shaft is a rotating body installing portion for attaching the rotating body, and a main body of the spindle excluding the rotating body setting portion of the main shaft as a material of the rotating body setting portion of the main shaft It is characterized by using ceramics having a lower thermal conductivity than the part. As the ceramic in this case, a material having low thermal conductivity is preferable among ceramics, and for example, zirconia ceramics is preferable.
According to this configuration, as the material of the rotating body installation part of the main shaft to which the target member of the runout accuracy measuring device or the rotary table is attached as the rotated body, the thermal conductivity is higher than that of the main body of the spindle excluding the rotating body installation part of the main shaft. Therefore, it is possible to effectively reduce the heat generated on the main shaft side from being conducted to the rotated body through the rotated body installation portion. Since only the rotating body installation part of the spindle is made of ceramics with low thermal conductivity, the material of the spindle body can be freely selected according to various requirements required for the spindle, such as metal materials, workability, cost, etc. Can be selected.
Zirconia ceramics have low thermal conductivity among ceramics, and can more effectively reduce the heat generated on the main shaft side from being conducted to the rotating body. In addition, zirconia ceramics is excellent as a material for the rotating body installation portion because it has functions such as high strength and corrosion resistance.
When this static pressure gas bearing spindle is used in, for example, a disk master manufacturing apparatus, a rotary table on which the disk master is mounted is attached to the rotating body installation portion as a rotated body, but heat generated by the main shaft is transmitted to the disk master. This reduces the relative position change between the irradiated part of the beam and the master surface due to thermal expansion of the spindle, and highly accurate information. Can be recorded.

Before SL is made of metal the spindle body portion excluding the driven rotating body installation portion of the spindle, a through hole penetrating in the axial direction around the driven rotating body installation section, wherein the main shaft main body and the driven rotating body installation section Are electrically connected to a metal rotating body attached to the through hole by a conductive wire wired in the through hole .
In the disk master production apparatus using this hydrostatic gas bearing spindle, the measurement result by the runout accuracy measuring device that measures the rotational runout precision of the spindle and the rotation position detection result of the spindle by the rotary encoder are used as the disk master on the rotary table. The position of the electron beam converging spot on the surface of the disk master is controlled and corrected so that the disk master can be exposed with high precision so that the disk master can be exposed with high precision. Alternatively, there is a case where only the rotational accuracy is measured for accuracy assurance or the like without controlling and correcting the beam convergence spot position. In these cases, the target member of the shake accuracy measuring device is attached to the rotating body installation portion of the main shaft, and the capacitance type displacement sensor is used as the shake accuracy measuring device in terms of normal measurement accuracy and ease of installation. Is used.
When measuring with this capacitance type displacement sensor, it is necessary to ground the AC current component in the target member due to the measurement principle. Either ground directly between the target member and ground, or between the target member and ground. In a required area, a portion facing each other through a minute gap is provided, and a capacitor portion having a large capacitance is formed and grounded.
In this hydrostatic gas bearing spindle, although ceramics having a lower thermal conductivity than the main body of the spindle excluding the rotating body installation part is used as the material of the rotating body installation part of the main shaft, the vibration is caused by the ground path having the above configuration. The target member of the accuracy measuring device can be reliably grounded.

Such hydrostatic gas bearing spindle to other configurations in this inventions, Oite the first configuration, the material of the main shaft body portion, except for the driven rotating body installation section of the main shaft is alumina ceramics, the main shaft A through-hole that communicates with each other in the axial direction is provided at the center of the rotating body installation portion and the main spindle main body, and the metal rotation shaft of the motor is provided at the end of the main shaft opposite to the rotated body installation portion. It is provided coaxially with the through hole, and the motor rotating shaft and a metal rotating body attached to the rotating body installation portion are electrically connected by a conductive wire wired in the through hole .
In the case of this configuration, zirconia ceramics is used as the material of the rotating body installation portion of the main shaft, and alumina ceramics having a smaller coefficient of thermal expansion than metal is used as the material of the main body of the main shaft. Thermal deformation caused by the difference in thermal expansion coefficient can be prevented at the joint with the main spindle body. Further, even if zirconia ceramics is used as the material of the rotating body installation portion of the main shaft and alumina ceramics is used as the material of the main body of the main shaft, a metal rotating body such as a target member attached to the rotating body installation portion is Since the conductive wire wired in the through hole is electrically connected to the motor rotating shaft, the rotating body can be easily grounded to the outside.

Hydrostatic gas bearing spindle according to still another configuration of this inventions is Oite the first configuration, the material of the main shaft body portion, except for the driven rotating body installation section of the main shaft is alumina ceramics, the main shaft A through-hole that communicates with each other in the axial direction is provided at the center of the rotating body installation portion and the main spindle main body, and the metal rotating shaft of the motor is disposed at the end of the main shaft opposite to the rotating body installation portion. Is formed coaxially with the through-hole, and a conductive plating layer is formed on the inner peripheral surface of the through-hole of the main shaft main body portion and the end surface in contact with the motor rotation shaft, and the metal that is attached to the plating layer and the rotating body installation portion The rotating body is electrically connected by a conductive wire wired in a through hole of the rotating body installation portion .
In the case of this configuration, even if zirconia ceramics is used as the material for the rotating body installation portion of the main shaft and alumina ceramics is used as the material for the main body of the main shaft, the metal rotation of the target member or the like attached to the rotating body installation portion The body is electrically connected to the motor rotating shaft through conductive wires wired in the through hole of the rotating body installation portion of the main shaft, the inner peripheral surface of the through hole of the main shaft main body portion and the end surface contacting the motor rotating shaft. Therefore, the rotated body can be easily grounded to the outside.

In the present invention, a disk made of a conductive material is fixed to the metal rotating shaft of the motor, and a conductive grounding member having a flat surface facing the surface of the disk through a minute gap is formed as a static pressure gas bearing. You may hold | maintain with the electroconductive holding member fixed to the housing of the spindle.
In this configuration, an alternating current component is passed from the motor rotating shaft through the disk, the conductive grounding member, and the conductive holding member by the action of the capacitor formed by the minute gap between the disk and the conductive grounding member. Since it is electrically connected to the housing, a metal rotating body such as a target member attached to the rotating body installation portion of the main shaft can be reliably grounded to the outside.

According to the present invention, a conductive earth member having a conductive fibrous member fixed to a disk made of a conductive material on the metal rotating shaft of the motor and having a conductive fibrous member in contact with the surface of the disk is provided as a static pressure gas bearing spindle. It may be held by a conductive holding member fixed to the housing. The fibrous form of the conductive fibrous member refers to a form in which a large number of fibers exist not only as thin as fibers but also through spaces.
In this configuration, since the disk and the conductive ground member are loosely contacted via the conductive fibrous member, the target member can be energized between the two members regardless of discharge and attached to the rotating body installation portion of the main shaft. The metal rotating body such as can be reliably grounded to the outside. Further, the presence of the conductive fibrous member does not hinder the rotation of the main shaft.

The static pressure gas bearing spindle according to the configuration of the reference proposal example is a static pressure gas bearing spindle including a static pressure gas bearing that rotatably supports a main shaft and a motor with a core that rotationally drives the main shaft. A motor rotor fixed to one end of the main shaft, a motor core disposed on the outer periphery of the motor rotor and facing the motor rotor via a predetermined gap, an excitation coil wound around the motor core, and a hydrostatic gas bearing spindle A motor case that covers the motor rotor, the motor core, and the exciting coil and that holds the motor core, a cooling water passage that surrounds the periphery of the motor core on the wall of the motor case, and the cooling water passage A water supply port for supplying cooling water from the outside and a drain port for draining the cooling water in the cooling water passage to the outside are provided. In addition, a low-temperature compressed air generator that converts compressed air introduced from the outside into low-temperature cold air, and the cold air that opens in the motor case and that is generated by the low-temperature compressed air generator flows into the motor case toward the excitation coil. And a cool air exhaust port for exhausting the cool air that has opened and flowed into the motor case to the outside of the motor case through the excitation coil.
According to this configuration, the motor case is provided with a cooling water passage that surrounds the periphery of the motor core, and cooling water is supplied to the cooling water passage from the outside, so that the motor case, the motor core, and the excitation coil can be cooled. Thus, heat generation in the cored motor can be reduced. Further, since the cool air generated by the ultra-low temperature air generator is caused to flow toward the exciting coil, the heat generation in the cored motor can be further reduced. Thus, the thermal expansion of the spindle can be miniaturized by reducing the heat generated by the cored motor. In a disk master production apparatus using this hydrostatic gas bearing spindle, when the main shaft is thermally expanded due to heat, a relative position change occurs between the beam irradiation unit and the disk master surface, and recording of high-precision information is hindered. However, since the heat generation in the motor with the core can be reduced as described above, it is possible to prevent a decrease in the accuracy of information recording due to heat.

The static pressure gas bearing spindle according to another configuration of the reference proposal example is a static pressure gas bearing spindle including a static pressure gas bearing that rotatably supports the main shaft and a coreless motor that rotationally drives the main shaft. A motor rotor fixed to one end portion of the main shaft, a rotor yoke fixed to one end portion of the main shaft and disposed on the outer peripheral side of the motor rotor, and facing the motor rotor via a predetermined interval, and between the rotor yoke and the motor rotor And an excitation coil disposed so as to be in non-contact with both members, and a motor case provided in a housing of a static pressure gas bearing spindle, covering the motor rotor, rotor yoke, and excitation coil, and holding the excitation coil. And an ultra-low temperature air generator that converts compressed air introduced from outside into ultra-low temperature cold air, A cold air supply port that opens into the motor case and causes the cool air generated by the ultra-low temperature air generator to flow into the motor case toward the motor rotor, and the cold air that opens and flows into the motor case flows into the inner periphery of the excitation coil. A cool air exhaust port for exhausting the motor case from the side through the outer peripheral side is provided.
According to this configuration, the cool air generated by the ultra-low temperature air generator flows into the motor case from the cool air supply port of the motor case toward the motor rotor, and the inflowed cool air passes through the excitation coil by the centrifugal force generated by the rotation of the motor rotor. Because it is exhausted out of the motor case from the cold air exhaust port, even cold air with low jet pressure generated by the ultra low temperature air generator,
The motor rotor, exciting coil, and rotor yoke can be air-cooled, and heat generation in the coreless motor can be reduced. In a disk master production apparatus using this hydrostatic gas bearing spindle, when the main shaft is thermally expanded due to heat, a relative position change occurs between the beam irradiation unit and the disk master surface, and recording of high-precision information is hindered. However, since the heat generation in the coreless motor can be reduced as described above, it is possible to prevent a decrease in the accuracy of information recording due to heat.

The static pressure gas bearing spindle according to still another configuration of the reference proposal example is a static pressure gas bearing spindle including a static pressure gas bearing that rotatably supports a main shaft and a coreless motor that rotationally drives the main shaft. A motor rotor fixed to one end portion of the main shaft; a rotor yoke fixed to one end portion of the main shaft and disposed on the outer peripheral side of the motor rotor; and facing the motor rotor via a predetermined interval; and the rotor yoke and the motor rotor An excitation coil disposed so as to be in non-contact with the two members, and a motor case provided in a housing of a static pressure gas bearing spindle, covering the motor rotor, rotor yoke, and excitation coil, and holding the excitation coil And having the excitation coil and the motor rotor held by the motor case A coil cover member made of a non-magnetic and electrically insulating material that covers the exciting coil in a sealed state in a non-contact state is provided in each of the rotor yoke and the rotor yoke, and cooling water is externally provided in the sealed space covered with the coil cover member. The motor case is provided with a water supply port for supplying water and a drain port for draining the cooling water in the sealed space to the outside.
According to this configuration, since the exciting coil is cooled in a completely sealed space covered with the coil cover member without being leaked, the exciting coil can be sufficiently cooled, and the coreless Heat generated by the motor can be effectively reduced. In the disk master manufacturing apparatus using this hydrostatic gas bearing spindle, the heat generation by the coreless motor in the hydrostatic gas bearing spindle can be reduced as described above, so that it is possible to prevent deterioration in information recording accuracy due to heat. .

Material before Symbol coil cover member may be a ceramic. The cooling water may be a fluorinated inert liquid.

Before SL paste Peltier element to the exciting coil, it may be intended to cool the exciting coil by controlling the Peltier element from the outside.

A cooling water passage for cooling the housing to the wall of the housing of the hydrostatic gas bearing spindle, a water supply port for supplying cooling water to the cooling water passage from the outside, and a drainage port for draining the cooling water in the cooling water passage to the outside It is also possible to provide a water passage tube that communicates the drain port with the water supply port of the motor case, and the cooling water in the cooling water passage is also used for cooling the exciting coil.
In this configuration, a water cooling system for the housing is provided in addition to the water cooling system for the excitation coil, and both water cooling systems are communicated with each other by a water tube so that the cooling water is used for both cooling the housing and the excitation coil. As a result, the number of water flow tubes that are dragged with the movement of the hydrostatic gas bearing spindle is reduced, and the adverse effects on speed fluctuations during the movement of the spindle are suppressed, and thermal deformation of the spindle is effectively reduced. it can.

In hydrostatic gas bearing spindle before Symbol Izuka, in hydrostatic gas bearing spindle in the disk mastering apparatus for exposing or rendering the recorded information by irradiating an electron beam or a laser beam to the resist applied on the surface of the disc master And the said to-be-rotated body may be a turntable which mounts the said disc original disc.
In this way, when applied to a disc master production device, the heat generated by the spindle can be reduced from being transferred to the disc master, so that the resist reaction speed instability and unevenness due to heat can be reduced, resulting in thermal expansion of the spindle. It is possible to suppress the relative position change between the beam irradiation portion and the master disk surface, and to record information with high accuracy.

A hydrostatic gas bearing spindle of the present invention includes a hydrostatic gas bearing that rotatably supports a main shaft, and a motor that rotates a main shaft by fixing a motor rotor to the main shaft, and rotates one end portion of the main shaft. In a static pressure gas bearing spindle as a rotating body installation part for mounting a body, the material of the rotating body installation part of the main shaft has a higher thermal conductivity than the main body of the spindle excluding the rotating body installation part of the main shaft. use physician the lower ceramics (first configuration), the said main shaft is made of the main shaft body portion, except the driven rotating body installation part is a metal, provided with a through hole penetrating in the axial direction center of the rotary member installation portion Since the main shaft body and the metal rotating body attached to the rotating body installation portion are electrically connected with the conductive wire wired in the through hole , the heat conduction in the main shaft can be effectively reduced, This static pressure gas bearing spindle When used in, for example, a disk mastering device, it becomes possible to record accurate information.
According to another aspect of the present invention, there is provided a static pressure gas bearing spindle according to the first configuration, wherein the material of the main body of the main shaft excluding the rotating body setting portion of the main shaft is alumina ceramics, and the rotating body setting portion of the main shaft And a through-hole that communicates with each other in the axial direction at the center of the main spindle body, and the metal rotary shaft of the motor is connected to the through-hole at the end opposite to the rotating body installation portion of the main spindle. Provided coaxially, this motor rotating shaft and the metal rotating body attached to the rotating body installation part are electrically connected by a conductive wire wired in the through hole, effectively reducing heat conduction in the main shaft In addition, when this static pressure gas bearing spindle is used in, for example, a disk master production apparatus, it is possible to record information with high accuracy.
According to still another aspect of the present invention, in the static pressure gas bearing spindle, in the first configuration, the material of the main body of the main shaft excluding the rotating body mounting portion of the main shaft is alumina ceramics, and the rotating body of the main shaft is installed. And a through-hole that communicates with each other in the axial direction at the center of the main shaft portion and the main shaft main body portion, and the metal rotation shaft of the motor is disposed at the end of the main shaft opposite to the rotating body installation portion. A metal rotating body that is provided coaxially with the inner peripheral surface of the through hole of the main shaft main body and an end surface that is in contact with the motor rotating shaft, and is attached to the plating layer and the rotating body installation portion. Is electrically connected by a conductive wire wired in the through-hole of the rotating body installation portion, so that heat conduction in the main shaft can be effectively reduced. For example, when this static pressure gas bearing spindle is used in a disk master production apparatus , Recording of accurate information becomes possible.

It is sectional drawing of the static pressure gas bearing spindle which concerns on 1st Embodiment of this invention. It is sectional drawing of the static pressure gas bearing spindle which concerns on other embodiment of this invention. It is a fragmentary sectional view showing the modification of the same static pressure gas bearing spindle. It is sectional drawing of the static pressure gas bearing spindle which concerns on other embodiment of this invention. It is sectional drawing of the static pressure gas bearing spindle which concerns on a reference proposal example . It is sectional drawing of the static pressure gas bearing spindle which concerns on the other reference proposal example . It is a cross-sectional view of a hydrostatic gas bearing spindle according to other references proposed example of et. It is a fragmentary sectional view showing the modification of the same static pressure gas bearing spindle. It is a cross-sectional view of a hydrostatic gas bearing spindle according to other references proposed example of et.

  A first embodiment of the present invention will be described with reference to FIG. The static pressure gas bearing spindle A is configured to support the main shaft 1 in a housing 2 in a non-contact manner by a static pressure gas bearing 3 and to rotate the main shaft 1 by a motor 6. Here, the static pressure gas bearing spindle A is configured as a part of the disk master manufacturing apparatus. The static pressure gas bearing 3 is provided on sleeves 5 a and 5 b that constitute the inner periphery of the housing 2. The static pressure gas bearing 3 includes a static pressure gas journal bearing 3a and a static pressure gas thrust bearing 3b. The hydrostatic gas journal 3a and the hydrostatic gas thrust bearing 3b are arranged in the housing 2 in the radial and axial bearing gaps (several μm to several tens of μm) between the sleeves 5a and 5b of the housing 2 and the main shaft 1, respectively. The main shaft 1 is supported in a non-contact manner by ejecting compressed gas from the nozzles 4a, 4b, 4c and 4d. The main shaft 1 has a flange 1ba on the outer periphery of the upper portion, and the hydrostatic gas thrust bearing 3b is configured to eject compressed gas into bearing spaces on both sides of the flange 1ba. Each nozzle 4a, 4b, 4c, 4d is connected to an external compressed gas supply source (not shown) via an air supply path 11 formed in the housing 2 and the sleeves 5a, 5b. The housing 2 includes an upper housing 2a that covers an upper side including the flange 1ba of the main shaft 1, and a lower housing 2b that covers a lower side from the flange 1ba of the main shaft 1. One sleeve 5a serving as the inner peripheral portion of the upper housing 2a is disposed to face the upper surface of the main shaft flange 1ba, and the other sleeve 5b serving as the inner peripheral portion of the lower housing 2b is provided below the lower surface of the main shaft flange 1ba and the flange 1ba. It is arranged to face the outer peripheral surface of the main spindle on the side.

  The motor 6 is disposed at the lower end of the main shaft 1 coaxially with a metal rotating shaft 7, a motor rotor 8 made of a permanent magnet provided on the rotating shaft 7, and an outer peripheral side of the motor rotor 8. The motor stator 9 and a synchronous servo motor with a core constituted by the motor rotor 8 and the motor case 10 covering the motor stator 9 are provided. The motor case 10 is fixed to the lower end of the lower housing 2b. The motor stator 9 includes a motor core 9a supported by the motor case 10 and arranged on the outer peripheral side of the motor rotor 8 with a predetermined gap therebetween, and an excitation coil 9b wound around the motor core 9a.

  A rotary plate (not shown) of the rotary encoder 12 is attached to the tip of the motor rotating shaft 7, and a head part (not shown) of the rotary encoder 12 is attached to the lower end of the motor case 10. The rotational position signal output from the rotary encoder 12 is fed back to the drive unit (not shown) of the motor 6 to reduce the rotational unevenness and rotational fluctuation of the static pressure gas bearing spindle A.

  The upper end portion of the main shaft 1 projects upward from the upper housing 2a, and constitutes a rotated body installation portion 1a for installing the target member 13b and the rotary table 14 of the runout accuracy measuring device 13. That is, the target member 13b and the rotary table 14 which are the rotating bodies are attached to the rotating body installing portion 1a coaxially therewith and are driven to rotate together with the main shaft 1. In addition to the target member 13b, the shake accuracy measuring device 13 includes a capacitance displacement meter 13a that detects the rotational shake accuracy of the main shaft 1 using the target member 13b as a target. The displacement meter 13a is provided on the upper housing 2a. It is installed at the upper end so as to face the target member 13b in the radial direction. Thereby, at the time of rotation of the main shaft 1, the rotation accuracy of the rotating body installation portion 1 a on the main shaft 1 can be measured by the shake accuracy measuring device 13. The target member 13 b of the runout accuracy measuring device 13 is a metal member, and here, the target member 13 b is directly attached to the rotated body installation portion 1 a of the main shaft 1. The turntable 14 is a body to be rotated on which a disk is mounted, which is also made of a metal member, and is here installed on the target member 13b. When the target member 13b is not attached, the turntable 14 is directly attached to the rotated body installation portion 1a.

  As the material of the rotating body setting portion 1a of the main shaft 1, ceramics having a lower thermal conductivity than the main shaft main body portion 1b excluding the rotating body setting portion 1a of the main shaft 1 is used. In this embodiment, zirconia ceramics is used. Zirconia ceramics have a low thermal conductivity of about 3 W (mk). On the other hand, the main spindle body 1b is made of metal. The zirconia ceramics used as the material of the rotating body installation portion 1a is not limited to pure zirconia, but various mixtures that serve as stabilizers, such as magnesium oxide (MgO), calcium oxide (CaO), yttrium oxide (Y2). It may be added with rare earth oxides such as O3). Zirconia is zirconium oxide (ZrO2).

  A through hole 15 penetrating in the axial direction is provided at the center of the rotating body installation portion 1a, and the target member 13b and the main spindle main body portion 1b, both of which are made of metal, are connected through the conductive wires 16 wired in the through hole 15. And are electrically connected. As a result, even if zirconia ceramics is used as the material of the rotating body setting portion 1a of the main shaft 1, the target member 13b attached to the rotating member setting portion 1a is replaced with the conductive wire 16, the metal main shaft body 1b, and the housing. 2 can be grounded to the outside. In this ground path, since the bearing gap between the metal main spindle body 1b and the sleeves 5a, 5b of the housing 2 is several μm to several tens μm, a capacitor having a large capacitance is formed, and an alternating current component is generated. Can be easily grounded.

In the disk master manufacturing apparatus using the static pressure gas bearing spindle, the beam irradiation is performed to irradiate the disk master on the rotary table 14 with the detection result by the runout accuracy measuring device 13 and the rotation position detection result by the rotary encoder 12. The position of the electron beam convergence spot on the surface of the disk master is controlled and corrected during exposure so that the disk master can be exposed with high accuracy. Alternatively, there is a case where only the rotational accuracy is measured for accuracy assurance or the like without controlling and correcting the beam convergence spot position. In these cases, since a capacitive displacement meter is used as the shake accuracy measuring device 13, it is necessary to ground the target member 13b.
In the static pressure gas bearing spindle A, although zirconia ceramics is used as the material of the rotating body installation portion 1a of the main shaft 1, the grounding of the target member 13b of the runout accuracy measuring device 13 is ensured by the configuration of the grounding path described above. Can be taken to.

  As described above, in the static pressure gas bearing spindle A, as a material of the rotating body installation portion 1a of the main shaft 1 to which the target member 13b of the runout accuracy measuring device 13 and the rotary table 14 are attached as the rotating body, Since low zirconia ceramics are used, it is possible to prevent the heat generated on the main shaft 1 side from being conducted from the rotary table 14 to the disk master mounted thereon. As a result, it is possible to prevent the reaction speed of the resist applied to the surface of the disk master from becoming unstable due to heat or causing unevenness of the reaction, and the recorded information can be exposed or drawn with high accuracy. Since the zirconia ceramic-made rotated body setting portion 1a is provided separately from the main spindle body 1b of the main spindle 1 and is attached to the main spindle main body 1b, the main spindle main body 1b has a main spindle made of steel or other metal material. A material suitable as 1 can be used.

  FIG. 2 shows another embodiment of the present invention. In the embodiment of FIG. 1, the hydrostatic gas bearing spindle A uses alumina ceramics as its material instead of making the main body 1b of metal. Further, in the center of the main spindle body 1b as well as the rotated body setting portion 1a, a through hole 17 penetrating in the axial direction is formed in the center of the main spindle body 1b with the through hole 15 of the rotated body setting portion 1a. They are provided so as to communicate with each other. Providing a metal motor rotating shaft 7 coaxially with the lower end of the main spindle body 1b is the same as in the embodiment of FIG. The target member 13b made of metal and the motor rotating shaft 7 are electrically connected to each other through the conductive wires 16 wired in the through holes 15 and 17. Further, a disc 18 made of a conductive material is fixed to the tip of the motor rotating shaft 7, and a conductive grounding member 19 having a flat surface facing the surface of the disc 18 with a minute gap is provided to the motor. The case 10 is held by an L-shaped conductive holding member 20 fixed to the lower end of the case 10. That is, the conductive holding member 20 is fixed to the housing 2 via the motor case 10. The disc 18 is made of metal.

  Thus, even if zirconia ceramics is used as the material of the rotating body installation portion 1a of the main shaft 1 and alumina ceramics is used as the material of the main body 1b, the target member 13b attached to the rotating body installation portion 1a is electrically conductive. The wire 16, the motor rotation shaft 7, the disk 18, the conductive ground member 19, the conductive holding member 20, the motor case 10, and the housing 2 can be grounded to the outside. On the surface of the conductive grounding member supporting portion 20a, which is a horizontal portion of the conductive holding member 20, facing the disk 18, a circular recess 20b for accommodating the disk-shaped conductive grounding member 19 so as to be movable up and down. Is formed concentrically with the disk 18. Further, the conductive grounding member support portion 20a is provided with three screw holes 21 penetrating through the circular recess 20b and arranged in the circumferential direction of the circular recess 20b, and screwed into these screw holes 21. The conductive ground member 19 is set on the set screw 22. Further, the conductive grounding member support portion 20a is provided with a screw insertion hole 23 penetrating through the central position of the recess 20b, and the conductive grounding member 19 is provided with a screw hole 24 in the central portion facing the screw insertion hole 23. Is provided. The conductive grounding member 19 is screwed into the screw hole 24 of the conductive grounding member 19 by screwing a bolt 25 inserted into the screw insertion hole 23 from below the conductive grounding member support 20a. Fixed to. Thus, the height of the conductive grounding member 19 is adjusted using the set screw 22 and the bolt 25 so that the conductive grounding member 19 is parallel to the circular plate 18 and the gap between the two members becomes an optimum gap of several μm to several tens of μm. It becomes possible. In this case, the optimum gap is a gap in which a capacitor having a large capacitance is formed between the disk 18 and the conductive earth member 19 so that an AC current can be easily grounded. Other configurations are the same as those in the embodiment of FIG.

  In particular, in this embodiment, the material of the rotating body setting portion 1a in the main shaft 1 is made of zirconia ceramics, and the material of the main shaft main body portion 1b excluding the rotating body setting portion 1a is made of alumina ceramic having a smaller thermal expansion coefficient than that of metal. Therefore, it is possible to prevent the occurrence of thermal deformation due to the difference in thermal expansion coefficient at the joint portion between the rotating body installation portion 1a and the main shaft main body portion 1b. In the disk master manufacturing apparatus using the static pressure gas bearing spindle A, when the main shaft 1 is thermally deformed, a relative position change occurs between the beam irradiation unit and the disk master surface, and high-precision information recording is performed. Although it is obstructed, it is possible to prevent thermal deformation of the main shaft 1 as described above, and therefore it is possible to prevent a decrease in the accuracy of information recording due to thermal deformation.

  FIG. 3 shows another configuration example of the ground path between the disk 18 and the conductive ground member 19. In this configuration example, a conductive fibrous member 19 a that loosely contacts the surface of the disk 18 is provided in a brush shape on the surface of the conductive ground member 19 that faces the disk 18. In this case, since the disk 18 and the conductive ground member 19 are electrically connected via the conductive fibrous member 19a, it can be directly energized. Further, since the conductive fibrous member 19a is loosely in contact with the surface of the disk 18, the rotation of the main shaft 1 is not hindered.

  FIG. 4 shows still another embodiment of the present invention. In the embodiment shown in FIG. 2, the hydrostatic gas bearing spindle A has a conductive plating layer 26a on the inner peripheral surface of the through hole 17 of the main spindle body 1b and the lower end face of the main spindle main body 1b in contact with the motor rotating shaft 7. , 26b, and a conductive wire in which a metal target member 13b attached to the rotating body installation portion 1a of the main shaft 1 and the plated layers 26a, 26b are wired in the through hole 15 of the rotating body installation portion 1a. 16 is electrically connected. The plating layers 26a and 26b may be a single layer of electroless nickel plating or gold plating having conductivity, or a plurality of layers in which these are laminated. Here, the conductive relay member 27 is fitted into the through hole 17 of the main spindle body 1b, and the conductive wire 16 is connected to the plating layer 26a via the conductive relay member 27, but the relay member 27 is omitted. Then, the conductive wire 16 may be directly connected to the plated layer 26a. Other configurations are the same as those in the embodiment of FIG.

Thus, even if zirconia ceramics is used as the material of the rotating body installation portion 1a of the main shaft 1 and alumina ceramics is used as the material of the main body 1b, the target member 13b attached to the rotating body installation portion 1a is electrically conductive. The wire 16, the conductive relay member 27, the plated layers 26 a and 26 b, the motor rotating shaft 7, the disk 18, the conductive ground member 19, the conductive holding member 20, the motor case 10, and the housing 2 can be grounded to the outside. . Moreover, the conductive wire wired in the long through-hole 17 of the main spindle body 1b is not necessary, and the assembly of the main spindle 1 is simplified.
In each of the above embodiments, the case where the motor 6 has a core has been described. However, the present invention can be similarly applied even when the motor 6 is coreless.

FIG. 5 shows a reference proposal example . In this hydrostatic gas bearing spindle A, in the embodiment of FIG. 1, an outer wall 10b is provided on the outer peripheral side of the peripheral wall 10a of the motor case 10 to form a double wall, and the cooling water surrounding the periphery of the motor core 9a between these two walls. A passage 28 is formed. The outer wall 10b of the motor case 10 is provided with a water supply port 29 for supplying cooling water to the cooling water passage 28 from the outside and a drain port 30 for draining the cooling water of the cooling water passage 28 to the outside. Further, a low-temperature compressed air generator 31 that converts compressed air introduced from outside into low-temperature cold air of 0 ° C. or less is provided, and cold air generated by the low-temperature compressed air generator 31 is provided at the lower end of the peripheral wall 10 a of the motor case 10. Is provided in the motor case 10 so as to flow toward the excitation coil 9b of the motor stator 9, and the cold air that has flowed into the portion where the peripheral wall 10a and the outer wall 10b of the motor case 10 overlap each other passes through the excitation coil 9b. A cold air exhaust port 33 for exhausting outside the case 10 is provided. Other configurations are the same as those in the embodiment of FIG.

In the static pressure gas bearing spindle A, the motor case 10 is provided with a cooling water passage 28 surrounding the motor core 9a, and cooling water is supplied to the cooling water passage 28 from the outside. The motor core 9a and the exciting coil 9b can be cooled, and the heat generation in the motor 6 can be reduced. Further, the cool air generated by the low-temperature compressed air generator 31 is caused to flow into the motor case 10 from the cool air supply port 32 of the motor case 10 toward the excitation coil 9b, and the inflowed cool air is passed through the excitation coil 9b to the motor case 10. Since the air is exhausted out of the motor case 10 through the cold air outlet 33, the motor core 9a can be simultaneously cooled from the inside and outside, and the heat generated by the motor 6 can be reduced to a very small value. That is, when the motor 6 is a motor with a core, the core 9a comes into contact with the motor case 10 and if the motor case 10 is cooled with water, the core 9a and the exciting coil 9b can be cooled. The motor rotor 8 is also cooled by blowing low-temperature compressed air from the above, and both are used in combination to enhance the cooling effect.
Thus, by reducing the heat generation in the motor 6, the thermal expansion of the main shaft 1 can be miniaturized. In the disk master manufacturing apparatus using the static pressure gas bearing spindle A, when the spindle 1 is thermally expanded by heat, a relative position change between the beam irradiation unit and the disk master surface occurs, and high-precision information recording is performed. Although it is obstructed, since the heat generation in the motor 6 can be reduced to a very small value as described above, it is possible to prevent a decrease in the accuracy of information recording due to heat.

FIG. 6 shows another reference proposal example . In this static pressure gas bearing spindle A, in the embodiment of FIG. 1, the motor 6 is a coreless synchronous servomotor instead of a synchronous servomotor with a core. That is, the coreless motor 6 in this case includes a motor rotation shaft 1bd formed integrally with the lower end portion of the main shaft 1, a motor rotor 8 made of a permanent magnet fixed to the motor rotation shaft 1bd, and an outer peripheral side of the motor rotor 8. And a rotor yoke 34 facing the motor rotor 8 with a predetermined interval, an excitation coil 35, and a motor case 10. The rotor yoke 34 is fixed to a flange-like yoke support portion 1bc formed integrally with the base portion of the motor rotation shaft 1bd in the main shaft 1. The exciting coil 35 is disposed between the rotor yoke 34 and the motor rotor 8 so as not to contact these two members. The motor case 10 is fixed to the lower end of the lower housing 2b, covers the motor rotor 8, the rotor yoke 34, and the exciting coil 35, and holds the exciting coil 35 via a coil base 36 such as resin.

  In addition, an ultra-low temperature air generator 44 that converts compressed air introduced from outside into ultra-low temperature cool air of about −30 to −40 ° C. is provided, and at the lower end of the motor case 10, the cool air generated by the ultra-low temperature air generator 44 is provided. A cool air supply port 32 is provided to flow into the motor case 10 toward the vicinity of the main shaft 1 at the lower end of the motor rotor 8, and the inflowing cool air is passed through the outer peripheral side from the inner peripheral side of the excitation coil 35 to the peripheral wall of the motor case 10. A cold air exhaust port 33 for exhausting the motor case 10 is provided. Here, as in the case of the embodiment of FIG. 1, the target member 13b and the rotary table 14 of the runout accuracy measuring device 13 attached to the rotating body installation portion 1a of the main shaft 1 are not shown, but other configurations are illustrated. This is the same as in the first embodiment.

If the motor 6 is a coreless motor as described above, there is an advantage that high rotational accuracy of the main shaft 1 can be easily obtained because the cogging torque is small. However, the exciting coil 35 is only held in the motor case 10 via a coil base 36 made of resin or the like, and is made of a metal core disposed in contact with the motor case 10 as in the case of a motor with a core. Does not have a part. For this reason, the heat generated in the excitation coil 35 during rotation cannot be transmitted to the motor case 10 side through the core portion, but is only transmitted to the motor case 10 side through the resin coil base 36. Cannot be cooled.
In the static pressure gas bearing spindle A, as described above, the cold air generated by the ultra-low temperature air generator 44 is caused to flow into the motor case 10 from the cold air supply port 32 of the motor case 10 toward the motor rotor 8, and the cold air that has flowed in. Is exhausted from the cool air exhaust port 33 of the motor case 10 to the outside of the motor case 10 through the inner periphery side to the outer periphery side of the excitation coil 35, so that the excitation coil 35 can be efficiently cooled by air cooling. Although the cold air from the ultra low temperature air generator 44 is an ultra low temperature of about −30 to −40 ° C., the jet pressure of the cold air is unlikely to be high due to the structure of the apparatus. However, in this embodiment, since cold air is introduced toward the vicinity of the main shaft 1 at the lower end of the rotating motor rotor 8, the introduced cold air is guided to the outer periphery by the centrifugal force of the motor rotor 8, and the motor rotor 8. The outer periphery of the motor and the inner periphery of the exciting coil 35, the outer periphery of the exciting coil 35 and the rotor yoke 34 are cooled, and smoothly flow into the cool air exhaust port 33 of the motor case 10 to be exhausted, thereby efficiently cooling the motor 6. Can do. Thus, when the motor 6 is a coreless motor, the ultra-low temperature air from the ultra-low temperature air generator 44 is blown and cooled in the vicinity of the motor shaft on the end face of the rotor 8. With this structure, even if the pressure of the air ejected from the ultra low temperature air generator 44 is weak, the cold air is guided to the outer periphery of the rotor 8 by the centrifugal force of the rotor 8 and discharged to the outside, whereby the motor 6 is cooled. The Therefore, a sufficient cooling effect can be obtained with the compact and inexpensive ultra-low temperature air generator 44, for example, without using another large and expensive compressed air cooling device as shown in FIG.

Figure 7 is showing the other references proposed examples et. In the static pressure gas bearing spindle A, the exciting coil 35 of the coreless motor 6 is covered with a coil cover member 37 in a sealed state in the reference proposal example of FIG. The coil cover member 37 is made of a material such as ceramics that is nonmagnetic and has electrical insulation and corrosion resistance, and is held at the lower end of the motor case 10. Further, at the lower end of the motor case 10, a water supply port 29 for supplying cooling water from the outside to the sealed space 50 covered with the coil cover member 37 and a drain port 30 for draining the cooling water of the sealed space 50 to the outside are provided. Provided. That is, in this reference proposal example , the above-described water cooling mechanism is adopted instead of the air cooling mechanism in the case of the reference proposal example of FIG. As the cooling water in this case, a fluorine-based inert liquid having excellent electrical insulation properties, high thermal and chemical stability, and inert and nonflammable properties is desirable. Although not shown, this cooling water is returned from the motor 6 to the chiller, cooled to a predetermined temperature, and then supplied to the motor 6 again to be circulated.

In this reference proposal example , since the exciting coil 35 is cooled in a completely sealed space 50 covered with the coil cover member 37 without being leaked, the exciting coil 35 is sufficiently cooled. Can do.

Figure 8 shows another exemplary configuration of a cooling mechanism excited magnetic coil 35. In this configuration example, the excitation coil 35 is cooled with the coolant and the Peltier element 38 by attaching the low temperature side of the Peltier element 38 to the excitation coil 35 and controlling the Peltier element 38 from the outside. Thereby, the cooling effect of the exciting coil 35 can be further enhanced.

Figure 9 is showing the other references proposed examples et. In the static pressure gas bearing spindle A, in the reference proposal example of FIG. 7, cooling water passages 39A and 39B for cooling the housing 2 are supplied to the wall of the housing 2, and cooling water is supplied to the cooling water passages 39A and 39B from the outside. The water supply ports 40A and 40B are provided, and the water discharge ports 41A and 41B are provided for draining the cooling water of the cooling water passages 39A and 39B to the outside. One cooling water passage 39A is provided in the upper end wall of the upper housing 2a in a rectangular shape, and the other cooling water passage 39B is provided in the peripheral wall of the lower housing 2b in a rectangular shape. The drain port 41A that opens to the cooling water passage 39A of the upper housing 2a communicates with the water supply port 40B that opens to the cooling water passage 39B of the lower housing 2b via the first water flow tube. Further, the drainage port 41B that opens to the cooling water passage 39B of the lower housing 2b is communicated with the water supply port 29 for cooling the exciting coil at the lower end of the motor case 10 through the second water flow tube 43, thereby cooling. Water is circulated and supplied from the cooling water passages 39 </ b> A and 39 </ b> B of the housing 2 to the sealed space 50 that covers the exciting coil 35. Other configurations are the same as those of the reference proposal example of FIG.

As described above, in this reference proposal example , the water cooling system of the housing 2 is provided separately from the water cooling system of the exciting coil 35, and these water cooling systems are made to communicate with each other through the water tubes 42 and 43, thereby supplying the cooling water to the housing. 2 and cooling of the exciting coil 35, the number of the water flow tubes 42 and 43 that are dragged with the movement of the static pressure gas bearing spindle A is reduced, so that the main shaft 1 is thermally deformed. It can be effectively reduced.

In this reference proposal example , the cooling water flowing from the cooling water passage 39A to the cooling water passage 39B and the cooling water flowing from the cooling water passage 39B to the sealed space 50 of the excitation coil 35 are guided by the water flow tubes 42 and 43. Although shown about the example, it is not restricted to this, You may provide piping and a flow path instead of these water flow tubes 42 and 43 in the housing 2 or the motor case 10. FIG.

Although not shown in the reference proposal examples of FIG. 5 and FIG. 7, the cooling water passages 39A and 39B similar to those in the embodiment of FIG. 9 are used in the reference proposal examples in combination with the water cooling system of the motor 6. You may form in the housing 2. FIG.

In each embodiment shaped state and Reference proposed example described above, a case has been exemplified using any of the multitude air supply type as the externally pressurized gas bearing 3, those porous air supply system as the externally pressurized gas bearing 3 Even if it is used, the same effect can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Main axis | shaft 1a ... To-be-rotated body installation part 1b ... Main axis | shaft main-body part 2 ... Housing 3 ... Static pressure gas bearing 6 ... Motor 7 ... Motor rotating shaft 8 ... Motor rotor 9a ... Motor core 9b ... Excitation coil 10 ... Motor case 13 ... Runout accuracy Measuring device 13b ... Target member (rotated body) of runout accuracy measuring device
DESCRIPTION OF SYMBOLS 15 ... Through-hole 16 of to-be-rotated body installation part ... Conductive wire 17 ... Through-hole 18 of spindle main-body part ... Disk 19 ... Conductive earth member 20 ... Conductive holding member 26a, 26b ... Plating layer 28 ... Cooling water passage 29 ... Water supply port 30 ... Drain port 31 ... Low temperature compressed air generator 32 ... Cool air supply port 33 ... Cool air exhaust port 34 ... Rotor yoke 35 ... Excitation coil 37 ... Coil cover member 38 ... Peltier elements 39A, 39B ... Cooling water passage 40A, 40B ... Water supply port 41A, 41B ... Drain port 42, 43 ... Water flow tube 44 ... Ultra-low temperature air generator

Claims (6)

A rotating body installation portion for attaching a rotating body to one end of the main shaft, comprising: a static pressure gas bearing that rotatably supports the main shaft; and a motor that rotates the main shaft by fixing a motor rotor to the main shaft. In the static pressure gas bearing spindle,
As the material of the rotary member installation portion of the spindle, have use a ceramic lower thermal conductivity than the main shaft body portion, except for the driven rotating body installation section of the main shaft, main shaft except the driven rotating body installation section of the main shaft The main body is made of metal, and a through-hole penetrating in the axial direction is provided at the center of the rotated body installation portion, and the main body and the metal rotated body attached to the rotated body installation portion are connected to the through hole. A hydrostatic gas bearing spindle characterized in that it is electrically connected by a conductive wire wired to the wire . A rotating body installation portion for attaching a rotating body to one end of the main shaft, comprising: a static pressure gas bearing that rotatably supports the main shaft; and a motor that rotates the main shaft by fixing a motor rotor to the main shaft. In the static pressure gas bearing spindle,
The main body of the main shaft excluding the rotating body installation portion of the main shaft using ceramics having a lower thermal conductivity than the main body of the main shaft excluding the main body of the rotating body as the material of the main body of the rotating body. The material of the part is alumina ceramics, and a through-hole that communicates with each other in the axial direction is provided at the center of the main body of the main body and the main body of the main shaft, and is opposite to the main body of the main body. A metal rotating shaft of the motor is provided coaxially with the through hole at the end of the motor, and a conductive wire in which the motor rotating shaft and a metal rotating body attached to the rotating body installation portion are wired to the through hole. A hydrostatic gas bearing spindle characterized by electrical connection. A rotating body installation portion for attaching a rotating body to one end of the main shaft, comprising: a static pressure gas bearing that rotatably supports the main shaft; and a motor that rotates the main shaft by fixing a motor rotor to the main shaft. In the static pressure gas bearing spindle,
The main body of the main shaft excluding the rotating body installation portion of the main shaft using ceramics having a lower thermal conductivity than the main body of the main shaft excluding the main body of the rotating body as the material of the main body of the rotating body. The material of the part is alumina ceramics, and a through-hole that communicates with each other in the axial direction is provided at the center of the main body of the main body and the main body of the main shaft, and is opposite to the main body of the main body. The metal rotating shaft of the motor is provided coaxially with the through hole at the end of the shaft, and a conductive plating layer is formed on the inner peripheral surface of the through hole of the main spindle main body and the end surface in contact with the motor rotating shaft. A hydrostatic gas bearing spindle, wherein the rotating member installation part and a metal rotating body attached to the rotating object installation part are electrically connected by a conductive wire wired in a through hole of the rotation object installation part. The conductive earth member according to claim 2 or 3 , wherein a disk made of a conductive material is fixed to a metal rotary shaft of the motor, and a conductive ground member having a flat surface facing the surface of the disk via a minute gap. A static pressure gas bearing spindle held by a conductive holding member fixed to the housing of the static pressure gas bearing spindle. In Claim 2 or Claim 3 , while fixing the disk which consists of a conductive material to the metal rotating shaft of the motor, the conductive grounding member which has the conductive fibrous member which contacts the surface of this disk, A hydrostatic gas bearing spindle held by a conductive holding member fixed to the housing of the hydrostatic gas bearing spindle. The hydrostatic gas bearing spindle according to any one of claims 1 to 5 , wherein a material of the rotating body installation portion of the main shaft is zirconia ceramics.

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