JP4418706B2 - Liquid suction / discharge control method and liquid suction / discharge apparatus using the same - Google Patents

Description

  The present invention is a liquid suction / discharge control capable of efficiently performing switching of introduction and discharge of liquid into a pump chamber of a vacuum pressure structure called a pressure vacuum vessel (hereinafter abbreviated as PVV) used in a liquid transfer section. The present invention relates to a method and a liquid suction / discharge device.

  When supplying a slurry (chemical solution) containing an abrasive to a chemical polishing apparatus or the like that polishes the surface of a semiconductor substrate, it is required to always supply the chemical solution continuously. For this purpose, for example, a slurry supply device is used, and a PVV described below is used for the chemical solution transfer section. PVV has a main structure of a pump chamber having a sealed space that can suck and introduce liquid into the room by applying negative pressure to the room and discharge (discharge) the liquid introduced by pressurizing from the room. The liquid to be sucked and discharged has an advantage that it is sent to a necessary portion without being brought into contact with a piston or other mechanical drive device (see Patent Document 1). In addition, in order to continuously supply a chemical solution as in the case of the slurry supply apparatus described above, two or more pump chambers that operate as described above are combined, and the negative pressure and pressurization of these pump chambers are alternately set. By doing so, the liquid is continuously supplied without interruption.

  With reference to FIG. 7, the structure of PVV is demonstrated more concretely. The PVV pump chamber includes a vacuum pump 3 for making the pump chamber 2 negative pressure, a suction valve 5 that allows liquid to be introduced into the pump chamber 2 that has become negative pressure, and pressurizing the pump chamber 2. A gas supply device 4 such as an inert gas and a discharge valve 6 for discharging liquid from the pressurized pump chamber 2. Then, switching between suction and discharge of the liquid into the pump chamber 2 includes a sensor 1 for detecting the presence or absence of the liquid, control of operations of the vacuum pump 3 and the gas supply device 4 by signals from the sensor 1, and This is performed by a control device (not shown) that controls opening and closing of the valve.

  Furthermore, when two PVVs are combined and the liquid is continuously supplied continuously, the two PVVs are operated as follows (see FIG. 7). First, the pump chamber of one PVV is pressurized to discharge the liquid, the discharge is stopped before the liquid reaches the lowest position, and at the same time, the pump chamber is set to a negative pressure to introduce the liquid. To fill the pump chamber to the highest position in the pump chamber. Furthermore, at the same time as stopping the discharge of the liquid from the pump chamber, the discharge of the liquid from the pump chamber is started by pressurizing the pump chamber filled with the liquid of the other PVV, Switch the discharge PVV. As a result, the liquid can be supplied without interruption. In this case, the timing of switching the liquid discharge from the pump chamber of each PVV is particularly important. This PVV switching is performed by a liquid level detection signal from the sensor. As the liquid level detection sensor, there are a float type, a capacitance type, a light transmission type, and the like. At present, a float type sensor is mainly used, but depending on the type of liquid, a capacitance sensor or an optical sensor may be used.

  Hereinafter, a method of switching between introduction of liquid into the pump chamber and discharge of liquid by a commonly performed float sensor will be described. Normally, as shown in FIG. 7, the float sensor 1 can be introduced into the pump chamber 2 at the position of the maximum liquid level (indicated as 1-1 in the figure), and the maximum amount of liquid is discharged from the pump chamber 2. In this case, the sensor 1 detects the presence or absence of liquid in the pump chamber 2 and inputs the information to the control device through the device. The liquid is introduced into or discharged from the pump chamber 2. Specifically, as shown in FIG. 8 (a), when liquid is introduced into the pump chamber and the liquid level rises, the float portion 12 of the sensor gradually rises and approaches the contact point, and the magnet provided in the float portion. The contact of the sensor is sucked to 11 (see FIG. 8B), thereby detecting that the liquid is filled up to the H position in the pump chamber. Contrary to this, the fact that the liquid has been discharged from the pump chamber and the liquid level has reached the L position is detected by separating the contact. Then, introduction of liquid into the pump chamber and discharge of liquid are performed according to these pieces of information.

  In the PVV used in the slurry supply apparatus used for polishing the semiconductor substrate, the liquid feeding operation using the float sensor as described above is always performed. In this case, the maximum amount position (hereinafter referred to as the H position) is used. Or the presence or absence of liquid at the minimum amount position (hereinafter referred to as L position) is detected about 20 to 40 times per hour, and the switching control of the operation of the two PVVs is performed based on the detection result. Yes. In the PVV method, the liquid level operation is usually up and down, and the liquid state and the liquid-free state are alternately repeated at the H position or L position of the liquid in the pump chamber in which the sensor is provided. For this reason, dirt in the sensor and the pump chamber gradually grows, and this may cause false detection. When the liquid feeding operation is stopped due to erroneous detection of the sensor, the slurry supply is interrupted, which greatly affects the polishing process of the semiconductor substrate. Therefore, in order to operate without interrupting the slurry supply, it is necessary to remove contamination in the sensor and the pump chamber so that no malfunction occurs.

  In order to prevent malfunction, periodic cleaning of the sensor and the pump chamber may be performed frequently. However, the cleaning operation is not only complicated, but the operation of the entire apparatus must be stopped each time, and the processing efficiency is significantly reduced. The frequency of cleaning varies depending on the operating conditions such as the chemical solution used, the liquid delivery speed, and the discharge pressure. Furthermore, depending on the environment used, the formation of a thin film on the sensor or pump chamber wall, so-called dirt, can be attached early. The current situation is that it is not possible to determine an appropriate period for carrying out periodic cleaning, and it is usually done early for safety reasons.

  The above-described float type sensor that has been used conventionally has a simple structure of detecting whether the liquid has reached a certain level using buoyancy by directly touching the liquid, so that the inner wall of the PVV pump chamber is It has the feature of being relatively strong against dirt. However, since the float type sensor is in direct contact with the liquid, there is a problem that the slurry adheres to the hinge part, or the liquid is mixed into the float of the hollow structure due to the negative pressure or pressurized environment in the pump chamber. This often causes malfunctions. On the other hand, the optical sensor is installed outside the pump chamber and can detect whether or not the liquid has reached a certain level in a non-contact manner. . For this reason, for example, an attempt has been made to automatically measure the amount of liquid in the pump chamber using a light transmission type sensor and to control the suction and discharge of the liquid into the pump chamber.

Japanese Patent Laid-Open No. 5-1671

  However, the light transmission type sensor is configured to detect whether the liquid has reached a certain level due to the change in the amount of light irradiated into the pump chamber. May not be done. In particular, depending on the type of liquid, for example, a slurry containing an abrasive, dirt adheres to the inner wall, and the subsequent growth is remarkable, or the viscosity is high and the amount of light temporarily changes greatly. In some cases, the filling state of the liquid in the pump chamber is not accurately detected, and erroneous detection may occur. Due to this erroneous detection, the timing of switching between liquid discharge and suction is not normal, and it is not possible to continuously supply the liquid, or it was originally not in the state of introducing the liquid into the pump chamber and switching the liquid discharge Nevertheless, there have been cases where operation has been switched and efficient operation has become impossible. Furthermore, it becomes necessary to perform the cleaning operation of the pump chamber more frequently than necessary due to erroneous detection, resulting in a decrease in operation efficiency.

  Accordingly, the object of the present invention is to accurately control the switching timing of liquid introduction and liquid discharge into the pump chamber by the light transmission type sensor even when the inner wall of the pump chamber is contaminated. As a result, it is an object to provide a liquid suction / discharge control method capable of continuously and efficiently feeding various treatment liquids such as slurry, and a liquid suction / discharge apparatus using the same. Furthermore, another object of the present invention is to calibrate the influence of fluctuations in the amount of light caused by dirt adhering to the inner wall of the pump chamber or the flow of the liquid despite the use of the light transmission type sensor. It is possible to accurately detect the state of the liquid, switch the suction and discharge operations of the liquid accurately, and realize the maximum use of the liquid between the H position and the L position. An object of the present invention is to provide a liquid suction / discharge control method capable of reducing the number of times of cleaning the room as much as possible and achieving excellent processing efficiency, and a liquid suction / discharge apparatus using the same.

（上記式中のＫは、閾値変数であって、２０〜８０％の範囲から選択される値である。） The above object is achieved by the present invention described below. That is, in the present invention, a mechanism for sucking a liquid with a negative pressure in a sealed pump chamber and a pressure in the pump chamber are discharged at both ends of a pump chamber having a vacuum pressure structure called a pressure vacuum vessel. and a mechanism, a method of controlling the suction and discharge of the liquid of the configuration cycle of suction and discharge of the pump Ru is changed, the light amount of a light-transmissive type sensor provided on at least one portion of the pump chamber at all times by these mechanisms Measure and sample N (N is an integer of 1 or more) each of the maximum and minimum values of light intensity every T seconds, calculate the average of these maximum and minimum values, respectively, and obtain the average value Is used to calculate the threshold value used for the next N times of suction and discharge, and the threshold value is compared with the light amount value sent from the sensor after the light amount value used for the calculation of the threshold value. , When the light value is greater than the threshold value, or when the light value becomes smaller than the threshold value, a liquid suction and discharge control method characterized by switching the operation of the discharge and suction.

(K in the above formula is a threshold variable and is a value selected from the range of 20 to 80%.)

  As a preferred embodiment of the present invention, in the above-described configuration, the light transmission type sensor detects the maximum amount of liquid that can be sucked into the pump chamber and the vicinity of the liquid level in the pump chamber when the maximum amount of liquid that can be discharged from the pump chamber is discharged. A liquid suction / discharge control method provided at two locations in the vicinity of the liquid surface of the pump chamber in the case of filling is mentioned. Moreover, as a preferable embodiment of the present invention, there is a liquid suction / discharge control method in which K is 40 to 60% in the above configuration.

  Another embodiment of the present invention includes at least a sealed pump chamber, a mechanism for sucking liquid by making the pump chamber negative, and a mechanism for discharging liquid by pressurizing the pump chamber. And a liquid suction / discharge device having a control mechanism using a light transmission type sensor for switching between liquid suction and discharge, wherein the control mechanism executes the liquid suction / discharge control method described above. It is a certain liquid suction / discharge device.

  According to the present invention, in a PVV used in a liquid transfer unit such as a slurry supply device, even when the liquid filled in the pump chamber is transparent and the inner wall is not contaminated, the inner wall of the pump chamber is contaminated. Even in the event of a failure, the light transmission type sensor can accurately detect the switching timing of the suction and discharge operations of the liquid into the pump chamber. Provided are a liquid suction / discharge control method capable of feeding liquid and a liquid suction / discharge apparatus using the same. In addition, according to the present invention, since the number of times of cleaning the pump chamber can be reduced, high processing efficiency is achieved.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. First, the operation principle of the liquid suction / discharge control method performed by the light transmission type sensor used in the present invention will be described. In the detection by the light transmission type sensor, as shown in FIG. 1, light is irradiated into the pump chamber from one direction, light that has reached through the pump chamber is received at the opposite position, and the amount of light is transmitted through the optical fiber 8. Connect to a transmissive sensor amplifier and display the amount of light received at that time in an analog form. Then, the light quantity value is used to detect the presence or absence of liquid, and the timing for switching between discharge and suction of liquid into the pump chamber is determined, and operation control is performed. In the present invention, the threshold value used to determine when to switch between the liquid discharge and suction operations is calculated as needed according to the process, and the obtained variable threshold value is compared with the light amount value that is constantly sent. By switching between the liquid discharge and suction operations, fluctuations in the amount of light caused by dirt and the like are dealt with, and accurate control matching the liquid state is performed.

A conventional method for switching between liquid discharge and suction is performed as follows. When the liquid is a slurry, the light quantity value may decrease due to the dirt on the inner wall as described above. Considering this, first, the light quantity when there is liquid and the light quantity when there is no liquid. Is measured in advance, the middle value thereof is determined, and the operation is switched when the light quantity value analog-displayed through the light transmission type sensor in actual operation becomes this value. This value is a threshold value. That is, the threshold value is obtained by the following calculation formula, and the value is set as a fixed value.If the light amount value is smaller than this threshold value, it is determined that there is liquid, and if the light amount is larger than the threshold value, there is no liquid. Judgment is made, and the operation of sucking and discharging the liquid is switched.

  For example, when the light quantity value measured in the absence of liquid (hereinafter referred to as a light quantity value without liquid) is 4000 and the light quantity value measured in the presence of liquid (hereinafter referred to as a light quantity value with liquid) is 20, The threshold value is (4000−20) × ½ + 20 = 2010. Control is performed so that the liquid suction and discharge operations are switched when the light quantity value constantly sent from the sensor passes 2010.

  However, in the above-described conventional method, when dirt or the like is generated on the inner wall of the pump chamber in actual operation, the light amount value displayed in an analog manner may be lower than the threshold value 2010 even though there is no liquid. When the liquid is present, it is erroneously detected. In order to prevent this, the threshold may be set higher, but in this case, it may be determined that there is no liquid even though the liquid is still sufficiently available and available. The detection that matches the state of the liquid in the pump chamber is not performed, and efficient processing cannot be performed. As described above, in the conventional control method, switching between the suction and discharge operations of the liquid in the pump chamber is not performed using the liquid between the H position and the L position in the pump chamber in a sufficient state. There was a problem that efficient processing was not performed.

  In contrast to the above-described problems of the prior art, the present inventors have fixed the threshold value in the conventional control method, and therefore cannot perform control corresponding to the amount of light that varies due to dirt on the walls in the pump chamber, fluid flow, or the like. In order to cope with dirt on the walls of the pump chamber and fluid flow, etc., we intensively studied the addition of a sequence control mechanism that automatically calibrates the threshold. As a result, the present inventors have found a sequence control mechanism that can effectively prevent erroneous detection of the sensor and that can achieve an efficient operation state that sufficiently utilizes the liquid in the pump chamber. Hereinafter, a sequence control mechanism for automatically calibrating the sensor threshold will be described.

  As described above, in the PVV, the liquid is sucked by making the inside of the pump chamber, which is a sealed space, into a negative pressure state with a vacuum pump or the like, but the liquid is sucked with the H position as a limit. On the other hand, when liquid is fed, the liquid is discharged by bringing the pump chamber into a pressurized state, but the liquid is discharged with the L position as a limit. Then, at least two PVVs that operate in this way are interlocked, and the timing of switching the suction / discharge operation of each PVV is appropriately controlled, so that the liquid is transferred efficiently and without interruption. As the shape of the PVV pump chamber used in the slurry supply device, for example, a cylindrical one having a diameter of about 100 mm and a length of about 600 to 700 mm is used. A vacuum and pressure application valve is connected to the upper end of the pump chamber, and a suction and discharge valve is connected to the lower end of the pump chamber.

  The PVV operation and the control mechanism for switching the operation for an example in which two PVVs are used and the light transmission type sensor is provided in one place will be described with reference to FIGS. In the description, the number of PVVs is two. However, the number of PVVs may be three, and even if any PVV is in the suction process, the liquid is discharged from any other PVV. In some cases, efficient and efficient liquid feeding is performed. Hereinafter, an example in which the light transmission type sensor is provided at two locations will be described. However, control is possible even at one location, and of course, it may be provided at three or more locations.

  First, the operation of the two PVVs will be described with reference to FIG. FIG. 3 is a diagram for explaining the operation to the last, and there are other connection destinations of sensors and valves in the actual machine. In FIG. 3A, the pump chamber 2 of PVV (hereinafter referred to as PVV-A) indicated by A is filled with a liquid, and all the valves are closed to stop the operation. In combination with this, an inert gas such as nitrogen is introduced from the gas supply device 4 through a valve into the sealed pump chamber 2 of PVV (hereinafter referred to as PVV-B) indicated by B, and the pump chamber The inside of 2 is in a pressurized state, the liquid is discharged through the valve 6, and the liquid is sent to the necessary part. In FIG. 3 (b), the state of FIG. 3 (a) advances, and the operation state is switched in the pump chamber 2 of the PVV-B by the control using the light transmission type sensor, and the liquid is sucked through the valve 5. Done.

  On the other hand, in the PVV-A pump chamber 2, an inert gas such as nitrogen is started to be introduced from the gas supply device 4 through the valve, the inside of the pump chamber 2 is pressurized, and the liquid is discharged through the valve 6. Be started. Further, in FIG. 3 (c), in the PVV-B pump chamber 2, the introduction of the liquid shown in FIG. 3 (b) has progressed, and the valves are filled with the liquid and all the valves are closed to stop the operation. It is in a state. Moreover, in the pump chamber 2 of PVV-A combined with this, discharge of the liquid shown in FIG.3 (b) is advancing. Further, the operation is switched by the control using the light transmission type sensor, and as shown in FIG. 3 (d), the liquid is sucked through the valve 5 in the pump chamber 2 of the PVV-A. . On the other hand, in the PVV-B pump chamber 2, an inert gas such as nitrogen is introduced from the gas supply device 4 through a valve, the inside of the pump chamber 2 is in a pressurized state, and the liquid passes through the valve 6. The liquid is discharged and delivered to the required location.

  The present invention is characterized in that the switching of the above operation is performed as follows using a light transmission type sensor. In the example shown in FIG. 3, the light transmission type sensor 1 is disposed in the vicinity of the H position of each pump chamber 2, and the operation is controlled as follows using this. As shown in FIG. 1, the light transmission type sensor is connected to a light transmission type sensor amplifier (not shown) by an optical fiber or the like, and the amount of light always measured by the sensor is a program logic controller (hereinafter referred to as PLC and PLC). Abbreviated). Then, using the value introduced to the PLC, the liquid suction / discharge control is performed as follows. The light transmission type sensor and the PLC are not particularly limited as long as the light quantity can be taken in analog form. For example, the PLC is a Keyence KV-700 series, and the light transmission type sensor is an FS-V20 series amplifier. As the optical fiber, FU-77V can be used. A reference example of the control of the suction and discharge operations of the liquid in the pump chamber using the light amount in the present invention will be specifically described below.

  An analog signal indicating the amount of light transmitted through the sensor is taken into the PLC. In actual operation, first, as the initial value of the threshold value, the maximum value of the light amount when there is no liquid and the minimum value of the light amount when there is the liquid are taken into the PLC as analog data. As an initial value of K, for example, a numerical value of 50% is input. Here, the suction and discharge of the liquid into the pump chamber 2 usually depends on the capacity of the pump chamber to be used, the type of liquid, and the speed at which the liquid is discharged, but usually about 20 to 40 times per hour. Repeated at a rate. Accordingly, the light amount constantly measured by the light transmission type sensor shows a high value in the absence of liquid and a low value in the state with liquid according to the repetition.

  FIG. 4 shows changes in the value of the amount of light input to the PLC when the liquid is a slurry. Although the measurement of the light quantity in PVV is always performed, in FIG. 4, the representative value of the low light quantity value is indicated by a black circle, and the representative value of the high light quantity value is indicated by a black square. That is, the black square is a data group of light quantity values when there is no liquid, and the black circle is a data group of light quantity values when there is liquid. When the slurry shown in FIG. 4 is used, it can be seen from the black square data group that the light quantity value in the absence of liquid tends to decrease as the number of processing days used increases. This is probably because the slurry adhered to the inner wall with use and the dirt gradually grew, so that the light amount value decreased day by day. However, the light amount value in the absence of the liquid has decreased for a while according to the number of days used, but sometimes shows a high value. This is presumably because a part of the grown dirt adhered to the inner wall dropped. On the other hand, from the black circle data group, the light amount value in the presence of liquid shows a low value regardless of the length of the processing days, but sometimes the light amount value becomes high. This is considered to be a decrease due to fluid flow or the like.

  In the conventional operation control method, as described above, the threshold value calculated from the light quantity value measured in the initial stage of processing is set as a fixed value (indicated by a bold line in FIG. 4), and the threshold value and the pump chamber The control is performed by comparing the light quantity values sent from the sensors provided in. That is, if the light quantity value from the sensor is lower than the threshold value (fixed value), it is determined that there is liquid. Conversely, if the light quantity value obtained above is higher than the threshold value (fixed value), the liquid quantity is It is judged that there is no operation control. Therefore, as shown in FIG. 4, since the value of the light amount fluctuates even though the liquid filling state is the same, the suction and discharge operations cannot be switched at an appropriate timing, which is efficient. The operation was not controlled.

  FIG. 5 shows a change in the amount of light input to the PLC when the liquid is transparent water. In this case, unlike the case of the slurry shown in FIG. 4, the problem of contamination of the inner wall does not occur, the light amount value in the absence of liquid, and the light amount value in the presence of liquid, regardless of the processing date, Indicates a substantially constant value. In the case of a transparent liquid, light does not reflect and easily passes through in the presence of liquid.Therefore, there is little difference in the amount of light from that in the absence of liquid, and the presence or absence of liquid in the pump chamber is compared to colored liquids that are difficult to transmit light. There is a problem that it is difficult to test. However, it is desired that the control for switching the suction / discharge operation of the liquid in the pump chamber be performed in a good state without changing the sensor depending on the type of liquid introduced into the pump.

（上記式中のＫは、閾値変数であって、２０〜８０％の範囲から選択される値である。）Ｋの初期値は、液の性状にもよるが、例えば、５０％とし、その後の液の状況に応じて適宜に変更すればよい。 In the present invention, a sequence control function for automatically calibrating the threshold value of the sensor described below is added to perform operation control. That is, in the present invention, a light transmission type sensor for detecting the presence or absence of liquid in the pump chamber is provided in at least one place of the PVV pump chamber, the light amount is constantly measured by the sensor, and the maximum light amount per T second is obtained. Sample N values and N minimum values (N is an integer of 1 or more), calculate the average value of N maximum values and minimum values, and use these average values to calculate The threshold value is calculated by using the threshold value for the next N times of suction and discharge operation control, and the threshold value is rewritten to a numerical value corresponding to the state of dirt in the pump chamber as needed. Then, when the light amount measurement value becomes larger than the threshold value, or when the light amount measurement value becomes smaller than the threshold value, switching between the discharge operation and the suction operation is performed.

(K in the above formula is a threshold variable and is a value selected from the range of 20 to 80%.) The initial value of K depends on the properties of the liquid, but is set to 50%, for example, and thereafter What is necessary is just to change suitably according to the condition of this liquid.

  FIG. 6 shows light transmission sensors (H) provided at two positions (refer to FIG. 3) of the H position and the L position of the pump chamber constituting the two PVVs A and B placed vertically. The light quantity value from the H sensor at the position and the L sensor at the L position is schematically shown. The upper side of FIG. 6 shows the light quantity value from each sensor installed in PVV-A, and the lower side shows the light quantity value from each sensor installed in PVV-B.

  As described above, in the PVV, normally, suction and discharge are repeated at a rate of about 20 to 40 times per hour and continuously operated. Therefore, in the present invention, first, the time taken when the discharge and suction of the liquid in the pump chamber is performed once without stopping is set to T seconds, and the maximum value of the light amount every T seconds is sampled N times, An average value of these values is calculated, and further, N samples are sampled from the minimum value of the light amount every T seconds, and an average value of these values is calculated. Then, the threshold value is calculated from these average values according to the above formula. The obtained threshold value is used to control the next N times of suction and discharge operations. In other words, when the light quantity measurement value becomes larger than the threshold value obtained above, or when the light quantity measurement value becomes smaller than the threshold value obtained above, the ejection and suction operations are switched. Here, N is an integer of 1 or more. Accordingly, when N is 1, the threshold value is calculated every time the liquid in the pump chamber is discharged and sucked, and the timing of the next discharge and suction operation is controlled by the obtained threshold value. Become. When N is 2, the threshold value is recalculated every time discharge and suction are repeated twice, and the threshold value used for control is rewritten. What is necessary is just to determine N suitably by the property of a liquid, the speed which sends a liquid, etc. Specifically, the value of N is preferably about 2 to 10. Further, it is more preferable that the threshold value is recalculated as 2 or 3 every time discharge and suction are repeated twice or three times.

  More specifically, in the example shown in FIG. 6, one discharge and suction in the pump chamber are performed every 140 to 180 seconds. In the example shown in FIG. 6, a case where the threshold value is calculated every N = 1, that is, every T = 140 to 180 seconds will be described. Here, although the light amount value is schematically shown by a straight line in FIG. 6, the actually transmitted light amount value is a fluctuating value as shown in the partially enlarged view in the figure. As the H sensor light quantity during T1, the maximum value of the light quantity value sent within the time indicated by T discharge 1 in the figure and the minimum value of the light quantity value sent within the time indicated by T waiting 1 The threshold value is calculated from The obtained threshold value is a determination value for the presence / absence of liquid within the time indicated by T2 in the figure, and is a numerical value for determining the timing for switching between the liquid discharge and suction operations. On the other hand, as in the previous case, as the H sensor light quantity during T2, the maximum value of the light quantity value sent within the time indicated by T discharge 2 in the figure and the time indicated by T wait 2 The threshold value is calculated from the minimum value of the light quantity value sent in. The obtained threshold value is a determination value for the presence / absence of liquid within the next suction and discharge operation time, and is a numerical value for determining the timing for switching between the liquid discharge and suction operations. In the example described above, N is set to 1, and sampling of the maximum value and the minimum value is performed by one ejection and suction. However, if the value of N is plural, the highest in the ejection and suction performed a plurality of times. Since the threshold value can be obtained from the average value and the minimum value, it is possible to more appropriately control the timing of the ejection and suction operations.

  The timing for switching between discharge and suction is determined as follows, for example. In the examples of FIGS. 3 and 6, the H sensor is provided near the H position and the L sensor is provided near the L position in both PVV-A and PVV-B. The threshold value calculated and set as described above is compared with the light amount value sent from time to time by these sensors. In the actual operation, the liquid level is lowered by the discharge operation, and when the liquid level passes the PV sensor detection position of PVV-A, that is, the light amount value is changed from a low value (with liquid) to a high value (no liquid). When rising, when the threshold value is exceeded, the operation of PVV-A is switched from discharge to suction. Next, the liquid level rises due to the suction operation, and when the liquid level passes through the HV sensor detection position of PVV-A, that is, the light amount value decreases from a high value (no liquid) to a low value (liquid present). When the threshold value is exceeded, the PVV-A operation is switched from suction to standby. In PVV-B, the discharge operation starts when PVV-A changes from discharge to suction. By repeating this operation, liquid feeding is performed continuously.

  Further, in the example of FIG. 6, as shown in FIG. 3, the pump chamber is in a standby state in a state where the pump chamber is filled with liquid, and therefore, in this system, the suction time needs to be shorter than the discharge time. . In the comparison between the light amount value from the sensor and the threshold value, the presence / absence of the liquid is sensed and operation switching such as ejection, suction, standby, etc. is performed. In the above description, the case where two sensors of the H sensor and the L sensor are installed has been described, but the same detection can be performed using only one of the sensors.

  Next, with reference to FIG. 2, an explanation will be given of a method for changing the apparatus when the control method (system) according to the present invention is applied to a conventional apparatus using an existing actual PVV capacitance sensor. To do. In the system configuration according to the present invention, a PLC manufactured by Keyence Corporation and a light transmission type sensor manufactured by Keyence Corporation were newly used and attached to an existing machine. Of course, if there is a sensor that can capture the amount of light in an analog manner, the system according to the present invention can be controlled without using a specific PLC and sensor. As a sensor that can be used in the system according to the present invention, a change in the presence or absence of liquid can be detected in an analog manner, and therefore, a light transmission type sensor is suitable as a sensor currently known. However, the present invention is not limited to this, and any sensor that can quantitatively (such as analog) output a change in the presence or absence of liquid can be used in the system according to the present invention. Also, the control device is not limited to the PLC, and any device having an analog input, a digital output, and an internal calculation mechanism may be used. The reason why the existing PLC is not used in the control device according to the present invention is to enable the construction of this system with an add-on.

The change procedure is as follows.
(1) First, the H and L capacitance sensors connected to PVV-A and B are removed. (2) Connect the new PLC to the existing PLC.
(3) Connect the new PLC and the optical sensor amplifier 7.
(4) Attach the sensor amplifier and fiber unit to each H and L sensor position.
(5) The transmitted light intensity analog signal of each sensor 1 is taken into the new PLC.
(6) The maximum value (without liquid) and the minimum value (with liquid) of each sensor light quantity are taken into the new PLC as analog data.
The contents of new PLC internal processing after taking in the light intensity analog data are described below.

Sampling N highest light quantity values taken in, and calculating the average value. Similarly, N minimum light quantity values are sampled and an average value is calculated. These average light quantity values are applied to the following threshold value calculation formula to calculate the threshold value. N can be arbitrarily set and is input to the PLC in advance. The formula for calculating the threshold is as follows.

  Here, K in the above equation is a threshold variable, but can be arbitrarily set. For example, it can be set in the range of 20 to 80%, more preferably in the range of 40 to 60%. By changing this variable, the calculation result of the threshold value can be increased (that is, it can be easily detected that there is no liquid) or can be lowered (that is, it can be easily detected that there is liquid). Therefore, this variable may be changed when it is desired to intentionally change the threshold calculation tendency depending on the nature of the chemical solution and the degree of internal contamination. It is good also as a specific value in all the processing periods, for example, can make an initial value 50% and can change after that according to the number of working days. By doing so, it is possible to switch the operation between discharge and suction while making the best use of the liquid in the pump chamber. That is, for example, when the contamination in the pump chamber has become large after the number of working days, even if there is sufficient liquid in the pump chamber, it is detected that there is no liquid if the K value is increased. Things happen. Accordingly, if the K value is set again low at this stage, it is easy to detect the presence of liquid, so that even in this state, switching between the discharge and suction operations can be performed accurately, which is effective.

(7) Compare the threshold calculated in the above (6) with the amount of light sequentially taken from the light transmission type sensor, and if the amount of light is larger than the threshold, the no-liquid signal; Output to the existing PLC.
(8) The threshold value calculation and the presence / absence detection of the liquid performed in (6) and (7) are continuously performed. For this reason, the threshold value is always rewritten to the optimal value calculated from the most recent light amount, and even if the dirt grows and the light amount decreases or the light amount increases for some reason, the threshold value can be followed. Generation of detection can be effectively prevented.

[Other false detection prevention measures]
In the PVV liquid feeding operation, the suction and discharge of liquid is performed by the H sensor with the liquid stopped and stopped, the other PVV-L sensor starts discharging without liquid, and the L sensor stops discharging without liquid and sucks. An operation such as start is performed. Here, the stain inside the PVV, which is the greatest cause of the decrease in the amount of light, is likely to occur at the portion where the liquid suction and discharge are switched. In order to prevent this, it is necessary to make it difficult for dirt to adhere to the beam path of the light transmission type sensor. The solution is to shift the liquid level from the time when the presence or absence of liquid is detected, and perform suction and discharge operations to shift the beam path from the site where dirt adheres and grows, further causing malfunctions. It becomes possible to make it difficult. Specifically, the movement is switched for 0.1 to 2 seconds from the time when the presence or absence of liquid is detected.

Example 1
FIG. 4 shows the light amount collected by the light amount data logging function to the memory card of Keyence PLC used when the liquid suction / discharge control method according to the present invention is executed, and the calculation result data of the threshold value. For the slurry, D-7100 manufactured by Cabot was used. In addition, the variable in the calculation formula for obtaining the threshold value was set to 50%, and N was set to 2. Logging interval: Every 24 hours. From FIG. 4, it can be seen that the amount of light that is judged as having no liquid, which is indicated by a black square, decreases due to the growth of dirt due to the slurry. Therefore, it is considered that a malfunction occurred when the threshold value obtained from the initial light amount was used as a fixed value. However, in this embodiment, as indicated by the white square, the threshold value used for controlling the operation by rewriting while calculating is decreasing according to the growth of dirt, and the liquid presence state is maintained for a long period of time. It was detected accurately.

Example 2
FIG. 5 shows calculation result data of the light amount and the threshold obtained in the same manner as in Example 1 except that the liquid was pure water. As a result, since pure water was fed, there was almost no change over time due to contamination during the period, the amount of light with liquid was maintained at a high value, and it did not decrease as in the case of slurry. The threshold value is an optimum value. In the slurry, the amount of light with liquid is very small because transmission of light is hindered, but in the case of pure water, the light transmission amount is large and the numerical value is high even with liquid. Even in the operating environment as shown on the left, since the threshold value is kept optimal, stable operation is possible.

  As an application example of the present invention, in the PVV used in the liquid transfer unit, the inner wall of the pump chamber of the slurry supply device or the like even when the liquid filled in the pump chamber is transparent and the inner wall is not soiled Even when soiling occurs, the light transmission type sensor can accurately detect the switching timing of the suction and discharge operations of the liquid into the pump chamber. A liquid suction / discharge control method capable of efficiently feeding liquid and a liquid suction / discharge apparatus using the same are exemplified. Examples of utilization of the present invention include a liquid suction / discharge control method that can reduce the number of times of cleaning the pump chamber and achieve high processing efficiency, and a liquid suction / discharge device using the same.

It is the figure which showed typically the light transmission type sensor used by this invention. 1 is a schematic diagram of an apparatus for executing a liquid suction / discharge control method according to the present invention. It is a schematic diagram for demonstrating switching of the operation | movement in the suction / discharge control method of the liquid concerning this invention. It is a figure which shows the relationship between the measured value of the light quantity at the time of performing the suction / discharge control method of the liquid concerning this invention, and the calculated threshold value. It is a figure which shows the relationship between the measured value of the light quantity at the time of performing the suction / discharge control method of the liquid concerning this invention, and the calculated threshold value. It is a figure for demonstrating the calculation method of the threshold value in the suction / discharge control method of the liquid concerning this invention. It is a schematic diagram for demonstrating the suction / discharge control method of the conventional liquid. It is a schematic diagram for demonstrating the sensor used for the suction / discharge control method of the conventional liquid.

Explanation of symbols

1: Sensor 2: Pump chamber 3: Vacuum pump 4: Gas supply device 5: Suction valve 6: Discharge valve 7: Optical sensor amplifier 8: Optical fiber 11: Magnet 12: Float section

Claims (4)

At both ends of a vacuum chamber having a vacuum pressure structure called a pressure vacuum vessel, there is a mechanism for sucking liquid by making the sealed pump chamber negative pressure, and a mechanism for discharging liquid by pressurizing the pump chamber, a method of controlling the suction and discharge of the liquid of the configuration cycle of suction and discharge of the pump by these mechanisms Ru is changed constantly to measure the amount of light by light transmission type sensor provided on at least one portion of the pump chamber, each T seconds The maximum value and the minimum value of the amount of light in each are sampled N (N is an integer of 1 or more), the average value of the maximum value and the minimum value is calculated, and the average value obtained is used to calculate To calculate a threshold value used for the next N times of suction and discharge, compare the threshold value with the light amount value sent from the sensor after the light amount value used for calculating the threshold value, and the light amount value is Threshold When it becomes larger than, or at the time when the light quantity value becomes smaller than the threshold value, the liquid suction and discharge control method characterized by switching the operation of the discharge and suction.

(K in the above formula is a threshold variable and is a value selected from the range of 20 to 80%.)   2 near the liquid level in the pump chamber when the light transmissive sensor discharges the maximum amount of liquid that can be discharged from the pump chamber, and near the liquid level in the pump chamber when the maximum amount of liquid that can be sucked into the pump chamber is filled. The liquid suction / discharge control method according to claim 1, wherein the liquid suction / discharge control method is provided at a location.   The liquid suction / discharge control method according to claim 1, wherein K is 40 to 60%.   At least the sealed pump chamber, a mechanism for sucking the liquid with the pump chamber under negative pressure, a mechanism for discharging the liquid with the pump chamber pressurized, and switching between suction and discharge of the liquid A liquid suction / discharge apparatus having a control mechanism using a light transmission type sensor for controlling the liquid suction / discharge control method according to any one of claims 1 to 3. A liquid suction / discharge device.

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