JP5871366B2 - Levitation transfer device - Google Patents

Description

  The present invention relates to a levitation transport apparatus that transports gas in a state where a gas such as compressed air is jetted to float a substrate.

  A flat panel display such as a liquid crystal display or a plasma display uses a substrate coated with a resist solution (referred to as a coated substrate). The coated substrate is formed by a coating apparatus that uniformly coats a coating solution such as a resist solution or a chemical solution on the substrate.

  A schematic diagram of the coating apparatus is shown in FIG. The coating device 80 includes a transport device 81 that transports the substrate W and a coating unit 82 that coats the substrate with a coating liquid. The coating unit 82 includes a base having a slit extending in a direction perpendicular to the direction of transport of the substrate W by the transport device 81, and discharges the coating liquid from the slit while transporting the substrate W at a predetermined speed. A coating film is formed.

  At this time, when it is desired to prevent foreign matter from adhering to the substrate W during the coating operation, gas is blown to the transport device 81 to float the substrate W with the pressure, and the substrate W is transported in a non-contact state. A levitation transport device may be used.

  An example of this levitation transport device is shown in FIG. This levitation transport device 91 has a suction port 93 for sucking gas in addition to the jet port 92 for jetting gas. Then, when the substrate W is floated, the gas is ejected from the ejection port 92 and simultaneously the substrate W is sucked from each suction port 93, so that the substrate W is floated as compared with the case where the substrate W is floated by performing only gas ejection. Therefore, the flatness of the substrate W can be maintained and the flying height of the substrate W can be precisely controlled.

  On the other hand, in the levitation transfer apparatus 91 as shown in FIG. 14, even if the output from the suction force supply means 94 that applies the suction force to each suction port 93 is constant, the position of the substrate W is Therefore, there is a problem that the suction force changes. A specific example is shown in FIG. As shown in FIG. 15A, when there are few portions where the substrate W exists above the levitation transfer device 91, the number of the suction ports 93 shielded from the upper side by the substrate W is small, and even if a gas is sucked, a leak occurs. Since it is large, the suction force of the suction port 93 that sucks the substrate W is small as indicated by V1 in the graph of FIG. On the other hand, when the portion where the substrate W is present above the levitation transfer device 91 increases as shown in FIG. 15B, the leakage decreases, and accordingly, as shown by V2 in the graph of FIG. The suction force of the suction port 93 that sucks W increases. As a result, the substrate W may be attracted to the levitation transport device 91, or the end portion of the substrate W may collide with the levitation transport device 91.

  As means for suppressing this change in suction force, for example, as shown in Patent Document 1 below, an electrically controlled valve is provided between the suction port and the suction force supply means, and the pressure value in the suction port measured by the pressure sensor is adjusted. Some control devices adjust the opening of the valve so that the suction force becomes a set value.

JP 2007-88201 A

  However, the levitation transport apparatus described in Patent Document 1 has a problem in that the control cannot catch up with the change in the suction force, and the suction force may not be constant. Specifically, in order to electrically control the valve to achieve the target opening, the control device calculates the appropriate opening based on the time for sending the pressure value measured by the pressure sensor to the control device and the pressure value. Response time including the time for the control device to operate the valve, etc., is required so that the calculated opening / closing time is reached, but if the transfer speed of the substrate W is increased, suction is performed before this response time elapses. The force may change. That is, a response delay occurs, and in this case, the opening degree of the valve that has been adjusted through the response time is no longer an appropriate opening degree, and as a result, accurate suction force control cannot be performed.

  In particular, in the coating apparatus as shown in FIG. 13, in order to uniformly apply the coating liquid from the coating unit 82 to the substrate W, the distance between the coating unit 82 and the substrate W is kept constant, that is, the substrate W floats. It is important to keep the height constant. Thus, if the transport device 81 cannot perform accurate suction force control and the flying height of the substrate W becomes unstable, there is a possibility that uneven coating occurs.

  Furthermore, there is a possibility that the substrate W and the transfer device 81 may come into contact with each other. As a result, the back surface of the substrate W may be damaged, a part of the substrate W or the transfer device 81 may be peeled off, and foreign matter may be generated. May occur and foreign matter may adhere or the internal circuit may be destroyed.

  The present invention has been made in view of the above-described problems of the prior art, and can quickly respond to a change in the flying environment accompanying the transport of the substrate and transport the substrate at a constant flying height. The object is to provide a levitating transport device.

In order to solve the above problems, a levitation transport apparatus according to the present invention is a levitation transport apparatus for levitating and transporting a substrate, and a direction in which a substrate is transported by a jet port for ejecting gas and a suction port for sucking gas. A floating stage that floats the substrate at a predetermined height by gas ejection and suction, suction force supply means for supplying suction force to the suction port, and suction force supply A main pipe communicating with the means, a branch pipe communicating with the main pipe and communicating with each of the suction ports, and a differential pressure damper provided in the middle of the main pipe, and the differential pressure damper includes: A path that communicates the inside of the main pipe and the outside air and a valve that shuts off the path, and the valve operates to open and close by an external force exerted on the valve by a differential pressure between the inside of the main pipe and the outside air, The valve operates in response to changes in differential pressure. By opening changes, maintaining a predetermined said pressure difference, the valve during high-speed conveyance of the differential pressure damper further substrate is provided to overshoot, the operating range of the valve in a predetermined differential pressure It is characterized by having a stopper that restricts it from opening too much from the range of the opening assumed from the amount of change .

According to the above levitation conveyance device, the differential pressure damper is provided in the middle of the main pipe communicating with the suction force supply means, and the valve of the differential pressure damper is caused by the external force exerted on the valve by the differential pressure between the main pipe and the outside air. By taking the action of opening and closing, the valve is directly operated by a change in the differential pressure as compared with the case where the valve is operated by control. Therefore, even when the suction force of the suction port changes immediately, such as when the substrate is floated and conveyed, the valve can operate quickly without delay in response, and the suction force is held at a predetermined value. Can be transported at a constant flying height. In addition, the differential pressure damper further limits the valve operating range so that it does not open too far from the range of opening assumed from the amount of change in the predetermined differential pressure, in preparation for the valve overshooting during high-speed conveyance of the substrate. By having the stopper, it is possible to prevent the pressure in the main pipe from becoming unstable and to maintain a stable suction force.

In another embodiment, the present invention is a levitating and conveying device that levitates and conveys a substrate, and has a plurality of ejection ports for ejecting gas in a direction in which the substrate is conveyed, and the substrate is ejected by gas ejection. A levitation stage that floats at a predetermined height, a gas supply means for supplying a gas to the jet outlet, a main pipe communicating with the gas feed means, a communication with the main pipe, and a communication with each jet outlet And a differential pressure damper provided in the middle of the main pipe, the differential pressure damper having a path that communicates the inside of the main pipe with outside air, and a valve that blocks the path. The valve operates to open and close by an external force exerted on the valve by a differential pressure between the main pipe and outside air, and the valve operates to change in accordance with the change in the differential pressure, thereby changing the opening degree. and holding said differential pressure, the differential pressure damper Further provided that the valve at the time of high-speed conveyance of the substrate is overshoot, have a limit stoppers so as not opened too much from the scope of the opening that is assumed the operating range of the valve from the change amount of the predetermined differential pressure It may be characterized.

According to the above levitation transfer apparatus, the differential pressure damper is provided in the middle of the main pipe communicating with the gas supply means, and the valve of the differential pressure damper is opened and closed by the external force exerted on the valve by the differential pressure between the main pipe and the outside air. By performing the operation, the pressure of the gas to be ejected can be maintained at a predetermined value as in the case of the above suction force, so that the substrate can be transported at a constant flying height. In addition, the differential pressure damper further limits the valve operating range so that it does not open too far from the range of opening assumed from the amount of change in the predetermined differential pressure, in preparation for the valve overshooting during high-speed conveyance of the substrate. By having the stopper, it is possible to prevent the pressure in the main pipe from becoming unstable and to maintain a stable gas pressure.

In addition, the valve is adjusted so as to be balanced in a state in which the path is opened in a state where no substrate is present on the floating stage and suction force is supplied from the suction force supply means. It is good to make it.

By doing so, even if the pressure difference is small, the opening degree of the valve changes immediately, and the suction force can be kept more stable.

Further, the valve is adjusted so as to be balanced in a state where the path is opened in a state where a substrate is not present on the levitation stage and gas is supplied from the gas supply means. good.

By doing so, even if the pressure difference is small, the opening degree of the valve changes immediately, and the gas pressure can be kept stable.

  According to the levitation transport apparatus of the present invention, it is possible to quickly respond to a change in the levitation environment accompanying the transport of the substrate and transport the substrate at a constant levitation height.

It is the schematic of the levitation conveyance apparatus in one Embodiment of this invention. It is the schematic of the levitation stage in this embodiment. It is the schematic of the differential pressure | voltage damper in this embodiment. It is a graph showing the change of the attractive force in this embodiment. It is the schematic of the levitation | floating stage in other embodiment. It is the schematic of the differential pressure | voltage damper in other embodiment. It is a graph showing the change of the jet power in other embodiment. It is the schematic of the levitation | floating stage in other embodiment. It is the schematic of the levitation | floating stage in other embodiment. It is the schematic of the levitation | floating stage in other embodiment. It is the schematic of the differential pressure | voltage damper in other embodiment. It is the schematic of the levitation | floating stage in other embodiment. It is the schematic of the coating device which has a conveying apparatus. It is the schematic of the conventional levitation conveyance apparatus. It is the schematic of an example of the board | substrate conveyance using the conventional levitation conveyance apparatus.

  Embodiments according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a levitation transport apparatus according to an embodiment of the present invention. The levitation conveyance apparatus 1 has a levitation stage 2 and a conveyance means 3. The substrate W is levitated by the levitation stage 2, and the conveyance means 3 grips the end of the substrate W. The substrate W is transported by moving in one direction.

  The levitation stage 2 ejects a gas from its surface and levitates the substrate W by the pressure of the ejected gas, which will be described in detail later. Further, in order to maintain the flatness of the substrate W that has floated, gas is also sucked at the same time.

  The transport means 3 is a mechanism that grips the substrate W to transport the substrate W, and includes a suction block that sucks the back surface of the substrate W, a clamping mechanism that grips the substrate W, and the like. In the present embodiment, the transport means 3 is a suction block that sucks the end of the back surface of the substrate W.

  Further, the transport unit 3 is mounted on a linear motion mechanism such as a linear stage, and the transport unit 3 can move in one direction by operating the linear motion mechanism. Here, the substrate W can be transferred by moving the transfer means 3 while holding the substrate W. In the following description, the direction in which the transport unit 3 transports the substrate W is the X-axis direction, the direction orthogonal to the X-axis direction on the horizontal plane is the Y-axis direction, and the direction orthogonal to these is the Z-axis direction. To proceed.

  Next, the levitation stage 2 in this embodiment is shown in FIG.

  The levitation stage 2 includes a levitation plate 10, a differential pressure damper 20, and suction force supply means 30.

  In this embodiment, the floating plate 10 is a flat plate having a jet port 11 and a suction port 12 on the surface. The levitation stage 2 may be formed of only one levitation plate 10 or a plurality of levitation stages 2 may be arranged to form the levitation stage 2.

  When a single floating plate 10 that is long in the substrate transport direction (X-axis direction) is provided, it is easy to float the front surface of the substrate W on the floating plate 10 with equal pressure. It is possible to float the substrate W. On the other hand, when a plurality of floating plates 10 that are short in the X-axis direction are arranged at an appropriate interval, it is necessary to float and convey the substrate W by a predetermined distance compared to the case where a single floating plate 10 is provided. Since the area of the floating plate 10 can be reduced, the floating stage 2 can be formed at low cost. Further, compared to manufacturing the long floating plate 10 as a single product, it is also effective in terms of cost to be able to form the floating plates 10 having a widely distributed size.

  Therefore, it is preferable to properly use the arrangement method of the floating plate 10 according to the required floating accuracy.

  For example, in the coating apparatus 80 shown in FIG. 13, a levitation stage having one long floating plate 10 is provided immediately below the coating unit 82, and the substrate W is loaded into and unloaded from the coating unit 82 before and after that. It is preferable to provide a levitation stage in which a plurality of short levitation plates 10 are arranged at intervals.

  FIG. 2 shows an example in which a plurality of floating plates 10 are arranged in the X-axis direction. However, the present invention is not limited to this, and the floating plates 10 may be arranged in the Y-axis direction, or may be arranged so as to obliquely intersect the X-axis direction or the Y-axis direction. In any case, as described later, the ejection port 11 and the suction port 12 must be arranged in the X-axis direction.

  The ejection port 11 is an opening provided on the surface of the floating plate 10 for ejecting a gas supplied from a gas supply unit (not shown), and the suction port 12 is given a suction force by a suction force supply unit 30 described later. These are openings provided on the surface of the levitation plate 10 for sucking the gas on the levitation stage 2.

  The levitation stage 2 formed by arranging one or a plurality of levitation plates 10 takes a form in which a jet port 11 and a suction port 12 are arranged in the X-axis direction. As a result, the flying height is controlled by jetting and sucking the gas at the jet port 11 and the suction port 12 at the position where the substrate W is present at any position on the floating stage 2. The substrate W can be levitated.

  The suction force supply means 30 is an exhaust device such as a vacuum pump or a blower, and performs exhaust with a constant output.

  The suction force supply means 30 is connected to the main pipe 13, and the pipe is branched into a plurality of branch pipes 15 at the opposite end of the main pipe 13, and these branch pipes 15 are connected to the suction ports 12. In this way, suction force is generated at each suction port 12 by causing the suction force supply unit 30 to communicate with each suction port 12 using a pipe and operating the suction force supply unit 30.

  Further, when branching from the main pipe 13 to the branch pipe 15, a tubular manifold 14 having a plurality of connection ports as shown in the figure may be used. By connecting the ends of the main pipe 13 and each branch pipe 15 to the manifold 14, the pipe can be easily branched.

  The differential pressure damper 20 is provided in the middle of the main pipe 13 and holds the differential pressure between the inside of the main pipe 13 and the outside air at a predetermined value.

  The configuration of the differential pressure damper 20 in this embodiment is shown in FIG.

  The differential pressure damper 20 has a manifold 21, a valve 22, and a shaft 23, and the valve 22 provided in the manifold 21 rotates around the shaft 23, and the opening degree of the valve 22 relative to the opening of the manifold 21. As a result of the change, the pressure difference between the inside of the main pipe 13 and the outside air is maintained at a predetermined value.

  The manifold 21 is a pipe having one end closed and one end open, and connection ports 27 are provided through the tube wall at two locations on the tube wall, and the main pipe 13 is connected to each connection port 27. Has been. Thus, the manifold 21 is provided in the middle of the route of the main pipe 13 and communicates with the outside air through the opening of the manifold 21. Further, the manifold 21 is provided with a hole through which a shaft 23 described later passes through the tube wall.

  The valve 22 is a flat plate having a shape equivalent to or slightly smaller than the shape of the opening of the manifold 21.

  The shaft 23 is a cylindrical rod, and is provided through the manifold 21 in the horizontal direction. Here, the valve 22 is fixed to the shaft 23 in a state in which the valve 22 is accommodated in the opening of the manifold 21, so that the valve 22 blocks the path through which the main pipe 13 communicates with the outside air.

  Here, when the shaft 23 rotates about its own central axis, the valve 22 also rotates. Thereby, the opening degree of the valve 22 with respect to the opening of the manifold 21 is changed, and the cutoff amount of the path through which the main pipe 13 communicates with the outside air is changed. It is preferable that a bearing 28 corresponding to the diameter of the shaft 23 is attached to the manifold 21 so that the shaft 23 rotates without shaking, and the shaft 23 passes through the bearing 28 and the through hole of the manifold 21.

  The valve 22 is fixed to the shaft 23 at a position above the center of gravity. Thereby, when the valve 22 is in a state where it does not receive an external force, the valve 22 is stably brought to rest in a vertical posture, for example, by its own weight without falling down.

  Further, a shaft 29 is attached to the shaft 23 so as to be orthogonal to the shaft 23, and a weight 24 is attached to the shaft 29. Thereby, a moment by the weight 24 and the shaft 29 is applied to the shaft 23.

  Here, by changing the position of the weight 24 along the shaft 29, that is, by changing the distance between the weight 24 and the shaft 23, the moment applied to the shaft 23 can be adjusted without replacing the weight 24. is there.

  Further, the manifold 21 is provided with a stopper 25 at a position where it interferes with the valve 22, so that the range of opening that the valve 22 can take is limited.

  The shaft 23 is provided with a resistance means 26 that can be a resistance to the rotational movement of the shaft 23. The resistance means 26 is capable of suppressing the rotational speed of the shaft 23, and includes a rotary damper that applies a braking force to the rotational motion by the viscous resistance of oil, a friction damper that provides a braking force to the rotational motion by the sliding resistance of rubber, and the like. Is mentioned.

  Next, the operation of the differential pressure damper 20 in the present embodiment will be described with reference to the arrow view of FIG.

  When the suction force supply means 30 operates and a differential pressure is generated between the inside of the main pipe 13 and the outside air, an external force that pushes the valve 22 from the high pressure side to the low side, that is, from the outside air side to the main pipe 13 side. An external force that pushes the valve 22 is applied to the valve 22 (see the arrow (a) in the arrow view of FIG. 3).

  When the external force is larger than the force of the valve 22 that returns to the original posture due to gravity, the valve 22 is moved and rotated by the external force, and the valve 22 is opened with respect to the opening of the manifold 21 (see FIG. 3 arrow). (See arrow (b) in the view). Therefore, the inside of the main pipe 13 and the outside air leak and the outside air flows into the main pipe 13 (see the arrow (c) in the arrow view of FIG. 3), and the differential pressure between the inside of the main pipe 13 and the outside air. Therefore, the external force applied to the valve 22 is reduced. Further, the greater the opening degree of the valve 22, the greater the leak amount.

  When the external force applied to the valve 22 by this leak becomes smaller than the force that the valve 22 tries to return to the original posture, the valve 22 moves in the closing direction. At this time, if there is an opening degree of the valve 22 in which the external force applied to the valve 22 and the force to return the valve 22 to the original posture exist before the valve 22 is completely closed, the valve 22 is stopped at the opening degree. . The pressure in the main pipe 13 at this time becomes equal to the suction force at the suction port 12 of the levitation stage 2.

  Here, the force with which the valve 22 tries to return to the original posture is obtained by the sum of the force due to the weight of the valve 22 and the moment caused by the weight 24 and the shaft 29 on the shaft 23, and can be adjusted by the weight 24 described above. is there. Therefore, by adjusting the weight 24, the opening degree of the valve 22 in a state where the suction force supply means 30 is operating can be adjusted.

  At this time, if the force that the valve 22 tries to return to the original posture with respect to the external force is too large, the valve is in a closed state until a certain amount of external force is applied to the valve 22, and even if a small change in differential pressure occurs May not open. On the other hand, if the force of the valve 22 to return to the original posture is too small, the valve 22 is balanced and stops in an open state, but the degree of change in the opening of the valve 22 due to the change in the differential pressure increases, There is a possibility that the valve 22 will open too much and interfere with the manifold 21 due to the change in the differential pressure.

  Therefore, when the valve 22 is in balance with the external force and is stationary, for example, when the valve 22 is slightly open, such as 10 degrees or less, the opening degree of the valve 22 even if a small change in differential pressure occurs. And the degree of change in the opening of the valve 22 can be reduced. Therefore, when the suction force supply means 30 is operated on the condition that there is no substrate W on the floating stage 2 and an appropriate suction force is obtained at the suction port 12, the valve 22 is slightly opened as described above. Thus, it is desirable to adjust the output of the suction force supply means 30, the weight of the valve 22, and the number and position of the weights 24.

  Next, in a state where the suction force supply means 30 is operated and the pressure difference has already occurred between the inside and outside of the valve 22, the pressure difference is small as when the substrate W passes over the levitation stage 2. When the time increases, the external force applied to the valve 22 increases with the increase, and the opening of the valve 22 immediately increases due to the external force. As a result, the amount of leak increases, the outside air enters the main pipe 13, and the differential pressure decreases. In this way, the operation of canceling the change in the differential pressure is performed, and the differential pressure is kept constant by returning to the original differential pressure.

  On the contrary, when the differential pressure decreases only for a short time, the external force applied to the valve 22 decreases with the decrease, and the opening degree of the valve 22 immediately decreases due to the external force. As a result, the amount of leak decreases, the differential pressure increases and returns to the original differential pressure, and the differential pressure is kept constant.

  In this series of operations, since the change in the pressure difference between the inside and outside of the valve 22 directly affects the opening of the valve 22, for example, the pressure inside the main pipe 13 is measured with a pressure gauge, Compared to a mechanism that electrically adjusts the opening degree of the valve 22 through control, such as changing the opening degree of the valve 22 in response, the valve 22 can operate quickly. When the pressure difference between the inside and outside of the valve 22 fluctuates in a short time, it is possible to maintain the pressure difference more stably than when the valve 22 is adjusted by control.

  Here, as in the case where the substrate W passes over the levitation stage 2 at a high speed, when the change in the differential pressure inside and outside the valve 22 is abrupt, the change in the differential pressure is slower than when the change is slow. Since the external force momentarily applied to the valve 22 is increased, the valve 22 may be opened excessively. At this time, the valve 22 exceeds the opening degree of the valve 22 that can be reached by the amount of change in the differential pressure (overshoot). If the estimated opening is exceeded, the differential pressure becomes too small this time, which may cause the valve 22 to close vigorously and cause overshoot.

  When the overshoot occurs in this manner, the pressure inside the main pipe 13 becomes unstable, so that the suction force at the suction port 12 of the levitation stage 2 becomes unstable, and the flying height of the substrate W can be kept constant. become unable.

  Therefore, in the present embodiment, a stopper 25 is provided to prevent this overshoot operation. That is, the position of the stopper 25 is set so that the opening degree of the valve 22 can be changed within the range of the opening degree of the valve 22 in accordance with the change amount of the differential pressure that can be taken in the transfer operation of the substrate W. It is preferable to prevent the operation of the excess valve 22.

  In order to prevent the overshoot operation, it is also effective to suppress the operation speed of the valve 22. Therefore, in this embodiment, the resistance means 26 is attached to the shaft 23 in order to suppress the operating speed of the valve 22, that is, the rotational speed of the shaft 23.

  In addition, since the resistance means 26 is provided and an appropriate resistance force is given to the rotation operation of the shaft 23, the valve 22 reacts excessively to a minute change in the differential pressure between the inside of the main pipe 13 and the outside air. Can be prevented or operated. As a result, it is possible to prevent the valve 22 from slightly vibrating during the operation of the suction force supply means 30.

  FIG. 4 is a graph showing changes in suction force when a differential pressure damper is provided in the suction pipe as in the present embodiment.

  In the case where the differential pressure damper 20 is not provided, as described above, as the transport of the substrate W advances and the number of the suction ports 12 of the levitation stage 2 shielded increases, the leakage at the suction ports 12 decreases as the figure decreases. As indicated by the circular plot 4, the suction force of the suction port 12 sucking the substrate W was large. On the other hand, when the differential pressure damper 20 is provided, the opening degree of the valve 22 of the differential pressure damper 20 changes and operates to maintain the differential pressure between the inside of the main pipe 13 and the outside air at a predetermined value. As the rhombus plot of FIG. 4 shows, it is possible to maintain a predetermined suction force even if the number of suction ports 12 to be shielded increases.

  Moreover, even when the conveyance speed of the substrate W is fast and the change in the situation where the substrate W shields the suction port 12 is abrupt, that is, even when the change in the differential pressure between the inside of the main pipe 13 and the outside air is abrupt. The stopper 25 and the resistance means 26 can stably hold the predetermined suction force without overshooting, and hold the predetermined suction force better than the adjustment of the opening degree of the valve 22 by control. be able to.

  Next, FIG. 5 shows a form in which the differential pressure damper is applied to the piping on the jet outlet 11 side of the levitation stage 2.

  The gas supply means 31 is a blower or the like, and supplies a gas such as compressed air or nitrogen taken from the outside to the downstream with a constant output.

  The gas supply means 31 is connected to the main pipe 33, and at the opposite end of the main pipe 33, the pipe is branched into a plurality of branch pipes 35, and these branch pipes 35 are connected to the respective jet ports 11. As shown in FIG. 5, a branch from the main pipe 33 to each branch pipe 35 may be configured using a manifold 34.

  As described above, the gas supply means 31 and each of the jet outlets 11 are communicated with each other by using the piping, and the gas supply means 31 is operated, whereby the gas is jetted out of each of the jet outlets 11.

  The detailed structure of the differential pressure damper 40 is shown in FIG.

  The differential pressure damper 40 is provided in the middle of the main pipe 33, and has a manifold 41, a valve 42, and a shaft 43, similar to the configuration in the case of the pipe provided on the suction port 12 side described above. The differential pressure between the inside and outside air is maintained at a predetermined value. Further, similarly to the differential pressure damper 20 described above, a weight 44 for adjusting the opening degree of the valve 42, a stopper 45 and a resistance means 46 for preventing overshoot of the valve 42 are provided.

  Assuming that the valve 42 opens to the outside air side, the weight 44 is mounted on the opposite side of the valve 42 as compared with the case where the differential pressure damper 20 is provided in the suction pipe.

  Next, the operation of the differential pressure damper 40 at this time will be described with reference to the arrow view of FIG.

  When the substrate W is transported on the levitation stage 2 and the substrate W is present on the ejection port 11, the gas flow above the ejection port 11 is obstructed by the substrate W, so the atmospheric pressure (jet power) at each ejection port 11 is Tend to be higher.

  At this time, since the pressure in the main pipe 33 increases and the pressure difference with the outside air increases, an external force that pushes the valve 42 from the main pipe 33 side to the outside air is applied to the valve 42 (( The valve 42 opens to the outside air side (see the arrow (b) in FIG. 6). By this operation, the gas in the main pipe 33 flows to the outside air side (see the arrow (c) in the arrow view of FIG. 6), and the change in the differential pressure is canceled out. Therefore, a predetermined differential pressure can be maintained. it can.

  Therefore, as shown in FIG. 7, it is possible to keep the jet power at each jet port 11 constant, and the floating transportation of the substrate W with a stable flying height is possible.

  Further, the differential pressure damper 40 can be applied to the levitation stage 2 having no suction port 12 and having only the ejection port 11 as shown in FIG. Stable floating transportation of the substrate W is possible.

  Further, FIG. 9 is a combination of the configuration in which the differential pressure damper 20 is provided in the suction pipe as shown in FIG. 2 and the configuration in which the differential pressure damper 40 is provided in the ejection pipe as shown in FIG. A floating stage 2 as shown may be configured.

  With the above-described levitation conveyance apparatus, it is possible to quickly respond to a change in the levitation environment accompanying the conveyance of the substrate and convey the substrate at a constant levitation height.

  In addition, as shown in FIG. 2, a plurality of floating plates 10 are arranged in this embodiment, but as described above, the floating stage 2 is formed by a single floating plate 10 as shown in FIG. Also good. Also in this case, as described above, the differential pressure damper may be provided only on the ejection port 11 side or on both the suction port 12 side and the ejection port 11 side. Alternatively, the floating plate 10 may have only the jet port 11 without the suction port 12, and a differential pressure damper may be provided in the jet pipe.

  Further, in the above description, the differential pressure damper 20 has a configuration in which the valve 22 rotates about the shaft 23 and the opening degree changes as shown in FIG. 3, but as shown in FIG. A configuration is provided in which a differential pressure between the main pipe 13 and the outside air is maintained at a predetermined value by providing a shaft 23 having an inclination and changing the opening degree by operating the valve 22 along the shaft 23 in the inclination direction. There may be.

  In the above description, only one differential pressure damper 20 is provided. However, in order to ensure a sufficient suction force or jet output with the valve 22 open, or for the piping in the apparatus. Depending on factors such as handling, a configuration having a plurality of differential pressure dampers 20 as shown in FIGS. 12 (a) and 12 (b) may be used. At this time, in order to stably transport the substrate W, it is desirable that the pressures of the main pipes 13 through which the differential pressure dampers 20 pass are equal.

DESCRIPTION OF SYMBOLS 1 Levitation conveyance apparatus 2 Levitation stage 3 Conveyance means 10 Levitation plate 11 Jet outlet 12 Suction port 13 Main piping 14 Manifold 15 Branch piping 20 Differential pressure damper 21 Manifold 22 Valve 23 Shaft 24 Weight 25 Stopper 26 Resistance means 27 Connection port 28 Bearing 29 Shaft 30 Suction force supply means 31 Gas supply means 33 Main piping 34 Manifold 35 Branch piping 40 Differential pressure damper 41 Manifold 42 Valve 43 Shaft 44 Weight 45 Stopper 46 Resistance means 80 Coating device 81 Transport device 82 Coating section 91 Floating transport device 92 Jet Outlet 93 Suction port 94 Suction force supply means W substrate

Claims (4)

A levitating and conveying device for levitating and conveying a substrate,
A levitation stage having a surface in which a plurality of ejection ports for ejecting gas and a suction port for sucking gas are arranged in a direction in which the substrate is conveyed, and the substrate is levitated at a predetermined height by ejecting and sucking the gas When,
Suction force supply means for supplying suction force to the suction port;
A main pipe communicating with the suction force supply means;
Branch pipes communicating with the main pipes and communicating with the respective suction ports;
A differential pressure damper provided in the middle of the main pipe;
With
The differential pressure damper has a path that communicates the inside of the main pipe with outside air and a valve that blocks the path, and the valve opens and closes by an external force exerted on the valve by a pressure difference between the inside of the main pipe and outside air. The valve is operated in accordance with the change in the differential pressure and the opening degree is changed to maintain the predetermined differential pressure ,
The differential pressure damper further limits the operating range of the valve so that it does not open too much from the range of opening assumed from the amount of change in the predetermined differential pressure, in preparation for the valve overshooting during high-speed transfer of the substrate. A levitating and conveying apparatus characterized by having a stopper . A levitating and conveying device for levitating and conveying a substrate,
A levitation stage that has a plurality of jet nozzles arranged in the direction in which the substrate is transported, and levitates the substrate at a predetermined height by gas ejection;
Gas supply means for supplying gas to the jet port;
A main pipe communicating with the gas supply means;
A branch pipe that communicates with the main pipe and communicates with each of the spouts;
A differential pressure damper provided in the middle of the main pipe;
With
The differential pressure damper has a path that communicates the inside of the main pipe with outside air and a valve that blocks the path, and the valve opens and closes by an external force exerted on the valve by a pressure difference between the inside of the main pipe and outside air. The valve is operated in accordance with the change in the differential pressure and the opening degree is changed to maintain the predetermined differential pressure ,
The differential pressure damper further limits the operating range of the valve so that it does not open too much from the range of opening assumed from the amount of change in the predetermined differential pressure, in preparation for the valve overshooting during high-speed transfer of the substrate. A levitating and conveying apparatus characterized by having a stopper . The valve is adjusted so as to be balanced in a state in which the path is opened in a state where a substrate is not present on the floating stage and a suction force is supplied from the suction force supply means. The levitation conveyance apparatus according to claim 1. The valve is adjusted so as to be balanced in a state where the path is opened in a state where a substrate is not present on the floating stage and gas is supplied from the gas supply means. The levitation conveyance apparatus according to claim 2.

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