JP2004262608A - Air flotation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flotation device low in compressed-air consumption and capable of stably floating a planar object by air pressure. <P>SOLUTION: The flotation device is provided with an air mixing means mixing supplied compressed air with air in the atmosphere adjacent to the device and is constituted so as to float the object by increasing an air-flow rate and jetting it to the object while decompressing the compressed air by mixing the air in the atmosphere. In a configuration example, primary side compressed air 5 supplied through compressed-air piping 4 is mixed with external atmosphere 6 through an air mixer 3 which is the air mixing means and decompression and volume increase are performed simultaneously. The compressed air increased in quantity is transferred through an enclosure 2 to a pressure spread plate 1 and is jetted to a lower part of the object, so that the object is floated by the air. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic floating device that floats a flat object such as a glass substrate for a display device or a printed circuit board into the air by blowing compressed air.
[0002]
[Prior art]
When a glass substrate for a display device or the like is transported in a clean room, a conveyor device using a belt or a roller has conventionally been used. Alternatively, means for transferring between devices by a robot arm using a vacuum suction pad is also widely used.
[0003]
On the other hand, in order to suppress the occurrence of damage or contamination on the back surface of the glass substrate, there is a technology that floats the substrate by ejecting gas from the surface of an air bearing mechanism or ceramic porous body arranged on the back surface of the substrate and transports it. It is disclosed in publications (for example, see Patent Documents 1 and 2).
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 06-127338 [Patent Document 2]
JP 2000-62951 A [0005]
[Problems to be solved by the invention]
At present, the size of the liquid crystal glass substrate exceeds 1 m × 1 m and is reaching 2 m × 2 m. Also, in PDP (plasma display panel), a glass size of 2 m square or more is used. However, a large amount of compressed air is required at low pressure to float the substrate with air, and the amount of air supply required for floating is proportional to the area of the substrate. The amount is also increasing, which is a problem. A typical levitation design requires 500 liters per minute of air supply per square meter of substrate area, and a 2m x 2m size requires 2000 liters of compressed air per substrate. .
[0006]
When substrate floating by such air is applied to many places in a clean room, it is necessary to prepare and distribute a large amount of compressed air at low pressure. The pressure of the compressed air required at this time is around 10 kPa, and a relatively powerful blower type pump is used to generate such a low pressure. Further, since the original pressure is low, the pipe requires a thick pipe having a diameter of about 50 mm to 100 mm in order to minimize the pressure loss during distribution. It is necessary to secure a space for this piping in the factory, and there is a problem that the degree of freedom of arrangement in installing the apparatus is limited. In addition, the compressed air is blown directly into the clean room, and is jetted directly below the substrate to collide with the back surface of the substrate, so that it needs to be extremely clean. For this purpose, a method is employed in which a filter device is installed immediately after the pressure is generated by the pump to remove minute foreign matter. Since this compressed air is large in volume at low pressure, the filter device becomes large and periodic maintenance of the filter is required.
[0007]
On the other hand, in a liquid crystal or PDP factory, high-pressure compressed air of usually 700 kilopascal or more is prepared for the purpose of supplying to a pad of a heavy air levitation stage in a mechanical unit driving force in a process apparatus, and the factory. It is distributed and plumbed in various places. This pipe has a diameter of about 10 mm because compressed air is used at a high pressure in a small amount. This high-pressure compressed air is also assumed to be used in the vicinity of the substrate, so that it is cleaned through a filter. Here, if the compressed air is supplied to the air levitation device by reducing the pressure with a regulator using the high-pressure compressed air, a pump, a filter and a thick pipe for generating a low pressure are not required, which is convenient. However, since a large amount of high-pressure compressed air is consumed, energy consumption is enormous, which is a major problem.
[0008]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to use a small amount of high-pressure compressed air prepared for factory use, and to reduce the consumption of compressed air. It is an object of the present invention to provide an air levitation device capable of floating a large-sized substrate while causing the substrate to float.
[0009]
[Means for Solving the Problems]
The present invention relates to a device for levitating a planar object with compressed air, and the object of the present invention is to provide an air mixing means for mixing supplied compressed air with air in the atmosphere near the device. This is achieved by reducing the pressure of the compressed air by mixing the air in the atmosphere, and simultaneously increasing the air flow rate and injecting and floating the object.
[0010]
Further, an air intake of the air mixing means is provided above the object, and is configured to take in clean air above the object from the air intake and mix with the compressed air; Heating means for heating the air mixed by the air mixing means; pressure adjusting means for adjusting the pressure of the primary-side supply compressed air taken into the air mixing means; and Pressure detection means for detecting pressure; and feedback control means for feeding back the pressure detected by the pressure detection means to the pressure adjustment of the compressed air supplied to the primary side; the primary supply supplied to the air mixing means. Pressure adjusting means for adjusting the pressure of the compressed air, floating amount detecting means for detecting the floating amount of the object, and the floating amount detected by the floating amount detecting means. Feedback control means for feeding back the amount to the pressure adjustment of the primary side supply compressed air; position detection means for detecting the position of the object; and opening / closing means for opening / closing the compressed air taken into the air mixing means. Compressed air opening / closing control means for controlling the opening / closing of the opening / closing means based on the detection information of the position of the object, and for mixing the opened / closed compressed air and the air in the atmosphere by the air mixing means. And a plurality of air levitation devices are arranged and configured;
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[0012]
FIG. 1 is a perspective view showing a configuration example of a levitation device according to a first embodiment of the present invention, and FIG. 2 is a partial cross-sectional view taken along line AA of FIG. In the present embodiment, the main body of the air levitation device includes a pressure diffusion plate 1 and a housing 2 supporting the pressure diffusion plate. The pressure diffusion plate 1 is made of a material such as porous ceramics, for example, and has a property of uniformly transmitting the pressure applied from below the diffusion plate to the entire upper surface while reducing the pressure inside the material. On the surface of the pressure diffusion plate 1, air is jetted at a uniform pressure. Further, the pressure diffusion plate 1 can be formed of a member in which minute holes of about 100 microns are arranged at regular intervals in a metal plate.
[0013]
The housing 2 mechanically supports the pressure diffusion plate 1 and has a distribution path for compressed air for applying uniform pressure to the pressure diffusion plate 1 and a reservoir tank for suppressing fluctuations in supplied air. Also serves a role.
[0014]
Compressed air is supplied to the housing 2 from outside through the air mixer 3. In FIG. 1, the air mixer 3 is mounted laterally on one wall surface of the housing 2, but the air mixer 3 may be connected near the center of the lower bottom plate of the housing 2, In order to make the pressure distribution inside the body 2 uniform, a plurality may be attached to the wall surface of the housing.
[0015]
In such a configuration, the high-pressure compressed air 5 supplied from the factory is guided to the air mixer 3 of the levitation device through the primary-side compressed air pipe 4. As shown in FIG. 2, the air mixer 3 is composed of a nozzle 7 for jetting compressed air on the primary side, and a mixing chamber for mixing air around the nozzle. A negative pressure is generated in an intake (hereinafter, referred to as an atmospheric suction port), and suction of the external atmosphere 6 is generated.
[0016]
The supply compressed air 5 mixed inside the mixer 3 and the sucked atmosphere 6 become the sum of the volumes of the two and becomes a low-pressure compressed air flow 9 inside the housing 2, which is transmitted to the pressure diffusion plate 1. Is done.
[0017]
As described above, the air levitation device according to the present invention mixes high-pressure compressed air supplied to the device with air in the air sucked by the ejector effect by using, for example, high-compression air prepared for factory use. The main feature is that the supply air flow rate is increased while the pressure is reduced, and the jet is ejected immediately below the object. The air in the atmosphere to be mixed is present in the immediate vicinity of the object to be levitated, and is clean air that has been sufficiently filtered such as in a clean room. In addition, the method of mixing air is characterized by using an ejector effect and having a device configuration in which dust is not generated by a driving mechanism or the like.
[0018]
With this configuration, it is possible to convert a small amount of compressed air supply at high pressure into a large amount of flow at low pressure without deteriorating the environment at the clean room level. It can supply a good air flow. Further, by using the ejector effect for mixing the compressed air, for example, when the supply pressure of 600 kPa is obtained in the factory piping of the compressed air, the pressure required for air floating of the object is reduced to 10 kPa. Then, since the air flow rate after mixing is obtained at least three times the primary supply flow rate, the generation capacity of compressed air required for levitation can be reduced to one third or less in preparation for factory power.
[0019]
Further, in the flotation device of the present invention, since the supply of compressed air to the flotation device is at a high pressure and in a small amount, even a small-diameter pipe is hardly affected by pressure loss, and the space for the compressed air pipe inside and outside the device is not required. Therefore, the degree of freedom in the arrangement of the device is increased. In addition, when handling high-pressure, small-volume compressed air, the pressure regulator and the switching valve can be small, so that a complicated pressure regulation system and switching system can be configured in the immediate vicinity of the flotation device. The design and handling can be simplified by incorporating them all into the.
[0020]
Next, a second embodiment of the air levitation device according to the present invention will be described.
[0021]
FIG. 3 is a cross-sectional view of the vicinity of the mixer according to the second embodiment, corresponding to FIG. 2, and the same components are denoted by the same reference numerals and description thereof will be omitted. In this embodiment, the air inlet of the mixer 3 is extended to above the object 11 to be levitated, and the clean air 6 by the downflow 14 in the clean room is directly supplied instead of the contaminated air near the apparatus. I am able to capture it. FIG. 3 shows a spray nozzle 12 and a substance 13 sprayed by the nozzle as an example of contaminating air near the apparatus. In this case, if the air mixer 3 does not extend the suction port upward, the sprayed substance 13 goes around from the end of the floating object and sucks the polluted atmosphere. By extending the air suction port to the upper part of the floating object, it is possible to take in clean air before spraying.
[0022]
Next, a third embodiment of the air levitation apparatus according to the present invention will be described.
[0023]
FIG. 4 is a cross-sectional view of the vicinity of the mixer according to the third embodiment, corresponding to FIG. 2, and the same components are denoted by the same reference numerals and description thereof is omitted. In this embodiment, a heater 15 is incorporated near the outlet of the mixer 3 as heating means for heating air. Electric power is supplied to the heater 15 from a power supply 16. The high-pressure compressed air and the atmosphere mixed in the mixer 3 are superheated by the heater 15, become low-pressure compressed air 9, and reach the pressure diffusion plate 1. At this time, the temperature of the compressed air 5 supplied through the pipe 4 is reduced by adiabatic expansion inside the mixer 3. Therefore, when the supplied compressed air 5 is already compressed to the room temperature in the factory while being compressed while flowing through the pipe 4, the temperature of the air flow 9 after being mixed with the atmosphere 6 becomes room temperature. Lower than. Further, the air flow 10 ejected through the pressure diffusion plate 1 is also adiabatically expanded, and thus has a lower temperature than the air flow 9. Here, by adjusting the current flowing through the heater 15, it is possible to set the temperature of the finally discharged air flow 10 in a range above and below room temperature, thereby realizing the setting on the low temperature side. A cooling device is not required.
[0024]
Next, a fourth embodiment of the air levitation apparatus according to the present invention will be described.
[0025]
FIG. 5 shows a configuration example of the levitation device according to the fourth embodiment in correspondence with FIG. 1, and the same components are denoted by the same reference numerals and description thereof is omitted. In this embodiment, after the pressure of the compressed air finally given to the pressure diffusion plate 1 is detected by the pressure detecting means (pressure sensor in this example) 17, the detection signal is amplified by the amplifier 18 and the pressure is adjusted. The pressure of the primary side supply compressed air 5 is changed by an electromagnetic pressure regulator 19 as a means, and feedback control is performed so that the pressure at the detection point of the pressure sensor 17 becomes constant. Such control is possible because the pressure of the air flow output from the mixer 3 is proportional to the supply pressure. According to this embodiment, compared to the case where feedback control is performed on a large amount of low-pressure compressed air finally given to the levitation device, control with high resolution and good linearity is performed to perform pressure control at high pressure. It is convenient because it can be performed. Further, since the pressure can be controlled with a small amount of air flow, there is a characteristic that energy loss is small.
[0026]
Next, a fifth embodiment of the air levitation apparatus according to the present invention will be described.
[0027]
FIG. 6 shows a configuration example of a levitation device according to the fifth embodiment in correspondence with FIG. 5, and the same components are denoted by the same reference numerals and description thereof is omitted. In this embodiment, in place of the pressure sensor 17 of the fourth embodiment, a distance sensor 20 is used as a flying height detecting means to detect the flying height of the floating object 11 (flying height in this example). ing. After the flying height signal detected by the distance sensor 20 is power-amplified by the amplifier 18, the compressed air supply pressure is feedback-controlled by the electromagnetic pressure regulator 19. In this embodiment, the flying height of compressed air (compressed air injected to the object 11) can be controlled so that the flying height of the object 11 is kept constant. According to this embodiment, as in the fourth embodiment, it is possible to perform control with low energy loss, high control resolution, and good linearity.
[0028]
Next, a sixth embodiment of the air levitation apparatus according to the present invention will be described.
[0029]
FIG. 7 is a perspective view illustrating a levitation device and a transport device according to a sixth embodiment, and illustrates an example of a configuration in which a plurality of air levitation devices are continuously arranged along a movement path of an object to be levitated. I have. In this embodiment, the floating object 11 is, for example, a liquid crystal glass substrate. The floating object 11 floats on the compressed air jetted by the pressure diffusion plate 1 over a plurality of floating devices, without frictional resistance. It moves in the direction of arrow B in FIG. The driving force for movement is given from the outside of the device by, for example, frictionally driving the end portion with a roller. Here, reference numerals 21 to 23 denote sensors (hereinafter, referred to as substrate presence sensors) for detecting that a glass substrate is present on the upper part of each floating device. Used as a direction position detecting means. Reference numerals 24 to 26 denote opening and closing means for opening and closing the primary supply compressed air supplied to each levitation device. In this example, electromagnetic valves are used. A control device 27 controls the electromagnetic valves 24 to 26 based on the detection signals of the substrate presence sensors 21 to 23. The control device 27 controls the opening and closing of the primary supply compressed air so that the compressed air is released only when the glass substrate 11 is present, and mixes the opened and closed compressed air with air in the atmosphere by the air mixer 3. This causes the glass substrate 11 to be sprayed.
[0030]
In such a configuration, for example, the control of the (N) th electromagnetic valve 25 is performed by the (N) th substrate presence sensor 22 installed immediately above the levitation device and the levitation device adjacent to both the (N) th substrate presence sensor 22. The logical sum of the (N-1) -th sensor 21 and the (N + 1) -th sensor 23, that is, when one of the substrate presence sensors 21 to 23 detects the glass substrate 11, the compressed air is released, and the substrate presence is detected. When all of the sensors 21 to 23 do not detect the substrate, control is performed to close the compressed air. Similarly, if a large number of levitation devices are controlled so as to stop the compressed air when the glass substrate 11 is not hung directly on both sides of the levitation device, if a long air levitation conveyor is configured, Unnecessary consumption of compressed air can be prevented.
[0031]
According to the sixth embodiment, the control of the opening / closing of the compressed air can be performed for the high-pressure, small-volume airflow, so that the influence of the opening / closing on the supply air pressure can be extremely reduced. In addition, since a small electromagnetic valve generally used in a factory can be used for opening / closing control, it is effective to use common components and reduce costs.
[0032]
It should be noted that the present invention is not limited to the embodiments described above, and it is a matter of course that the present invention includes a form in which technical matters of the embodiments are combined.
[0033]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
(1) There is no need to prepare a large amount of low-pressure compressed air as a utility in the factory, and a small amount of high-pressure equipment prepared for driving the mechanism can be shared, so that double investment in pneumatic utility can be avoided.
(2) A place for installing a thick pipe for delivering a large amount of low-pressure compressed air is not required.
(3) Since the compressed air supplied to the device has a high pressure and a small capacity, in the case of an application that is combined with a mechanism that requires driving by compressed air, only one type of compressed air piping is required, and the structure of the device is reduced. And the degree of freedom of installation of the device is increased.
(4) For the control of a large amount of pneumatic air at a low pressure used for air levitation, a commercially available pneumatic control device for a high pressure and a small flow rate can be used, and the apparatus cost can be reduced.
(5) Since a large amount of low pressure air control used for air levitation can be converted into a small amount of high pressure air control, control with high resolution and high linearity can be performed.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a configuration example of a levitation device according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA of FIG.
FIG. 3 is a cross-sectional view showing a structure near an air mixer of a levitation device according to a second embodiment.
FIG. 4 is a sectional view showing a structure near an air mixer of a levitation device according to a third embodiment.
FIG. 5 is a perspective view illustrating a configuration example of a levitation device according to a fourth embodiment.
FIG. 6 is a perspective view illustrating a configuration example of a levitation device according to a fifth embodiment.
FIG. 7 is a perspective view illustrating a configuration example of a levitation device according to a sixth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pressure diffusion plate 2 Housing 3 Air mixer 4 Primary compressed air piping 5 Primary supply compressed air 6 Intake air 7 Primary compressed air jet nozzle 8 in air mixer 8 Primary compressed air Air flow 9 ejected from ejection nozzle 9 Flow of low-pressure compressed air reaching pressure diffusion plate 10 Flow of air ejected from pressure diffusion plate 11 Planar floating object 12 Spray nozzle 13 Sprayed substance 14 Down flow in clean room 15 Heater 16 Heater power supply 17 Pressure sensor 18 Amplifier 19 Electromagnetic pressure regulator 20 Distance sensor 21 (N-1) th substrate presence sensor 22 (N) th substrate presence sensor 23 (N + 1) th Substrate presence sensor 24 (N−1) th solenoid valve 25 (N) th solenoid valve 26 (N + 1) th solenoid valve 27 Controller

Claims (6)

An apparatus for levitating a planar object with compressed air, comprising air mixing means for mixing supplied compressed air and air in the air near the apparatus, and mixing the air in the air to form the object. An air levitation apparatus characterized in that the compressed air is decompressed and, at the same time, the air flow rate is increased, and the air is jetted and floated on the object. An air inlet of the air mixing means is provided above the object, and is configured to take in clean air above the object from the air inlet and mix with the compressed air. The air levitation apparatus according to claim 1, wherein The air levitation apparatus according to claim 1, further comprising a heating unit configured to heat the air mixed by the air mixing unit. Pressure adjusting means for adjusting the pressure of the compressed air supplied to the primary side taken into the air mixing means, pressure detecting means for detecting the pressure of air mixed by the air mixing means, and pressure detected by the pressure detecting means 2. The air levitation apparatus according to claim 1, further comprising a feedback control unit that feeds back to the primary side supply compressed air pressure adjustment. Pressure adjusting means for adjusting the pressure of the primary side supply compressed air to be taken into the air mixing means, floating amount detecting means for detecting the floating amount of the object, and the floating amount detected by the floating amount detecting means. 2. The air levitation apparatus according to claim 1, further comprising a feedback control unit that feeds back the pressure of the compressed air supplied to the primary side. Position detecting means for detecting the position of the object, opening and closing means for opening and closing compressed air taken into the air mixing means, and controlling opening and closing of the opening and closing means based on detection information of the position of the object; A compressed air opening / closing control unit for mixing the compressed air and the air in the atmosphere by the air mixing unit, and a plurality of air levitation devices are provided. 2. The air levitation device according to 1.

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