JP2011038856A - Film thickness measuring device and film thickness measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film thickness measuring device improving the accuracy of on-line measurement, and also to provide a film thickness measuring method. <P>SOLUTION: A film thickness measuring device 100 measures the thickness of a web 20 on-line. For measurement of a film thickness, the film thickness is measured in advance during low speed transportation with a small influence of entraining of air, and the measured value is regarded as a master value (S02). After the transportation speed reaches a production target transportation speed, the difference between a measured value of the film thickness by on-line measurement and the master value, that is, the change amount is determined for measurement during high speed transportation (S05). After calculation of the change amount, the measurement result of the film thickness obtained during the high speed transportation is corrected with the change amount (S06). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a film thickness measuring apparatus and a film thickness measuring method for measuring the thickness of a test film having a strip shape in a non-contact manner. For example, the present invention relates to a film thickness measuring apparatus and a film thickness measuring method that are used in a process of manufacturing an electrode plate for a battery and measure the thickness of a test film online.

  For example, an electrode plate used for a lithium ion battery is manufactured by applying an active material to both surfaces of a strip-shaped metal foil. Specifically, in the manufacturing process of the electrode plate, an active material paste is applied to both sides of the metal foil, the active material paste is dried, the dried active material paste is rolled with a metal foil with a press roll, and the thin film after rolling Is cut to a suitable width and length.

  As described above, in the manufacturing process of the electrode plate, a strip-shaped thin film in which layers of the active material paste are formed on both surfaces of the metal foil is formed. As a film thickness measuring method for measuring the thickness of the thin film, there is known a method of cutting out a part of the thin film after rolling and measuring the film thickness with a contact-type film thickness measuring device when offline. For online measurement, for example, Patent Document 1 and Patent Document 2 disclose a film thickness measuring apparatus that measures a film thickness distribution in the width direction by scanning a laser displacement meter in the width direction.

JP 2002-257506 A JP 2009-47665 A

  However, the conventional film thickness measurement technique described above has the following problems. That is, since the thickness of the thin film after rolling is affected by the thermal expansion of the press roll, the rear end side tends to be thinner than the unwinding front end side. Therefore, there is a request (for example, a request for feedback to the press roll) that the film thickness history in the transport direction from the front end to the rear end should be detected with high accuracy.

  Therefore, it is conceivable to use a non-contact type film thickness measuring device disclosed in Patent Document 1 or the like to measure the thickness of the thin film after rolling on-line. However, in online measurement, the thin film floats from the reference roller due to air entrainment, resulting in measurement errors. This error tends to become more noticeable as the speed of transport of the thin film increases.

  The present invention has been made to solve the above-described problems of the prior art. That is, an object of the present invention is to provide a film thickness measuring apparatus and a film thickness measuring method capable of increasing the accuracy of online measurement.

  A film thickness measuring apparatus for solving this problem is a film thickness measuring apparatus for measuring the thickness of a test film having a strip shape, and is provided from the surface of a reference roller that is a roller for stretching the test film. A first displacement meter for measuring the distance, and a second displacement meter for measuring the distance from the surface of the test film stretched on the reference roller, based on the measurement results of the first displacement meter and the second displacement meter. An online measurement unit that calculates the thickness of the test film, a master acquisition unit that acquires a master value as a reference for the thickness of the test film before the transport speed of the test film reaches the target production speed, A change amount calculation unit that calculates the difference between the measurement value in the online measurement unit and the master value as a change amount after the master value is acquired and the transport speed of the test film reaches the target speed; Correction unit that corrects the measured value in the unit using the variation calculated by the variation calculation unit It is characterized in that it comprises.

  The film thickness measuring apparatus according to the present invention measures the thickness of a film to be measured on-line, and measures in advance a master value serving as a film thickness reference in a state where the influence of air entrainment is small. Then, after the transport speed of the test film reaches the target production speed, the amount of change that is the difference between the measured value of the film thickness by online measurement and the master value is obtained when starting measurement at the high speed transport. Then, after the change amount is calculated, the film thickness measurement result obtained during high-speed conveyance is corrected using the change amount.

  That is, in the film thickness measuring apparatus of the present invention, the amount of change that is a measurement error during high-speed conveyance is obtained based on the master value. This amount of change includes an error that occurred during high-speed conveyance, that is, a floating part due to air entrainment. And in the film thickness measuring apparatus of this invention, the measurement result of the film thickness obtained during high-speed conveyance is correct | amended using the variation | change_quantity. For example, correction is performed to cancel the measurement error corresponding to the change amount. As a result, improvement in measurement accuracy can be expected.

  In addition, the master acquisition unit of the film thickness measuring apparatus of the present invention performs online measurement within a period in which the transport speed of the film to be measured is a second target speed that is lower than the target speed before reaching the target speed. The measurement value obtained by the section may be acquired as a master value. That is, the amount of floating of the test film due to air entrainment is smaller in the low-speed conveyance period at the second target speed than in the high-speed conveyance period at the target speed. For this reason, the value measured during this low speed conveyance period is estimated to have a small measurement error. Therefore, the value measured during this low speed conveyance period is taken as the master value. This eliminates the need for off-line film thickness measurement and allows all measurements to be performed online. For this reason, there is no reduction in operating rate due to offline measurement.

  Moreover, the master acquisition part of the film thickness measuring apparatus of this invention may acquire the thickness of the to-be-tested film measured at the time of offline as a master value. In other words, off-line film thickness measurement is not affected by floating of the test film due to air entrainment. Therefore, when off-line, a part of another film to be tested in the same lot is cut out, and the value obtained by measuring the film thickness is used as a master value, so that it can be expected that the film thickness can be corrected with higher accuracy.

  The change amount calculation unit of the film thickness measuring apparatus of the present invention may calculate the change amount after the start of conveyance of the test film and after the tension of the test film becomes constant. When the transport of the test film is accelerated, the tension of the test film becomes unstable and air entrainment tends to occur. For this reason, the measured value of online measurement is also unstable and the accuracy is lowered. Therefore, the tension of the test film is measured, and the amount of change is calculated by looking at the time when the tension is stable. This can be expected to improve accuracy.

  In addition, the film thickness measuring apparatus includes a second correction unit that corrects the master value as the thickness of the test film until the tension of the test film becomes constant after acquisition of the master. Good. While the tension is unstable, the accuracy of on-line measurement is low, and good products tend to be misjudged as defective. Therefore, the erroneous determination is avoided by canceling the online measurement result until the tension of the film to be measured becomes constant and performing a correction to output a master value that is a non-defective value.

  The correction unit of the film thickness measuring apparatus of the present invention detects the amount of movement of the reference roller in the conveyance direction, and synchronizes with the machining cycle of the upper roller positioned upstream of the reference roller in the conveyance direction of the test film. It is recommended to correct by taking In other words, by obtaining variations in the processing cycle of the upper roller (periodic thickness variation of the test film caused by roller eccentricity, etc.) and reflecting variations in the processing cycle during correction, the accuracy can be further improved. Can be expected. For example, when the film thickness measuring device measures the thickness of the test film after the rolling process, the upper roller corresponds to a press roll in the rolling process.

  Further, the first displacement meter of the film thickness measuring device of the present invention is an optical displacement meter, and the reference roller is preferably subjected to a finishing process for reducing the mirror surface. That is, it can be expected to reduce the measurement error by reducing the specular reflection component by reducing the mirror surface of the reference roller surface. Note that the finishing process for reducing the mirror surface corresponds to, for example, roughening and matting or coloring.

  The finishing process may be a process of projecting fine particles onto the surface of the reference roller. That is, by projecting the fine particles, it is possible to prevent the surface roughness from deteriorating while matt. And since the deterioration of surface roughness is suppressed, the transfer damage to a thin film can be reduced. Furthermore, since innumerable recesses are formed on the surface of the reference roller, an air escape field is generated, and it can be expected that the floating amount of the test film due to air entrainment is reduced.

  Further, the present invention is a film thickness measuring method for measuring the thickness of a test film having a band shape, wherein the distance from a reference roller surface, which is a roller for stretching the test film, is measured by a first displacement meter. Measure the distance from the surface of the test film stretched on the reference roller with the second displacement meter, and determine the thickness of the test film based on the measurement results of the first and second displacement meters. An online measurement step to calculate, a master acquisition step to acquire a master value as a reference for the thickness of the test film before the transport speed of the test film reaches the production target speed, and a master acquisition step after the master value is acquired. After the transfer speed of the test film reaches the target speed, the change amount calculation step for calculating the difference between the measurement value in the online measurement step and the master value as the change amount, and the measurement value in the online measurement step Correction to be corrected using the amount of change calculated in the calculation step It includes thickness measuring method which comprises a step.

  According to the present invention, a film thickness measuring apparatus and a film thickness measuring method capable of increasing the accuracy of online measurement are realized.

It is a block diagram which shows a part of electrode plate manufacturing process concerning embodiment. It is a figure which shows schematic structure of the film thickness measuring apparatus concerning embodiment. It is a figure which shows the concept of thin film floating by air entrainment. It is a flowchart which shows the measurement procedure of the film thickness measuring apparatus concerning embodiment. It is a graph which shows the relationship between a film thickness measured value and time, and the relationship between a thin film conveyance speed and time. 6 is an enlarged graph showing the relationship between the measured film thickness and the time shown in FIG.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a film thickness measuring apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. In the present embodiment, the present invention is applied to a film thickness measuring device that measures the thickness of a thin film formed in the process of manufacturing an electrode plate, which is a manufacturing process of a lithium ion secondary battery.

The lithium ion secondary battery to be manufactured includes a positive electrode plate in which a positive electrode active material (for example, lithium nickelate (LiNiO ₂ )) is applied to both sides of an aluminum foil, and a negative electrode active material ( For example, a negative electrode plate coated with graphite is used. These electrode plates are wound, for example, by sandwiching a separator (for example, polyethylene) between these electrode plates, and sealed in a case together with the electrolyte, thereby forming a wound type secondary battery. This embodiment will be described as a film thickness measuring device that is incorporated in the electrode plate production line as described above and measures the thickness of the thin film that becomes the electrode plate online.

[Electrode plate manufacturing process]
First, a part of the manufacturing process of the positive electrode plate will be described with reference to the block diagram shown in FIG. Each processing shown in FIG. 1 is realized by one transport device. A film thickness measuring device is incorporated in the conveying device.

  In this embodiment, three positive electrode active material pastes are applied in advance along the longitudinal direction on an aluminum foil having a thickness of about 15 μm, a width of about 600 mm, and a length of about 3600 m. A strip-shaped thin film wound into a roll is prepared as an unwinding roll. This thin film becomes the base material of the positive electrode plate. In addition, the dimension of the unwinding roll is an example, and is not limited to this.

  The transport device of this embodiment unwinds a strip-like thin film (hereinafter referred to as “web”) from a winding roll, and transports the web in the order of steps shown in the direction of the arrow in FIG. And each processing is performed in the conveyance process. The processed web is wound into a roll by a winding roll.

  Specifically, as shown in FIG. 1, the transport device of this embodiment includes an unwinding unit 1, a first slitter unit 2, a reservoir unit 3, a press unit 4, a foil unit press unit 5, and a film. A thickness measuring unit 6, a CPC unit unit 7, a second slitter unit 8, an ultrasonic cleaner 9, an inspection unit 10, and a winding unit 11 are provided.

The unwinding unit 1 unwinds the web from the unwinding roll.
The 1st slitter part 2 is equipped with a cutting blade, and cut | disconnects a web continuously to a longitudinal direction. In this embodiment, two cutting blades are provided, and two gaps where the paste is not applied are simultaneously cut out of the web unwound from the unwinding portion 1. Therefore, the webs output from the first slitter unit 2 are three webs. Each of the three webs has a configuration in which there are non-application portions on both sides in the width direction and an application portion in the center.

  The reservoir unit 3 gradually increases the interval between the three webs formed by the first slitter unit 2 and adjusts the tension and conveyance speed of each web.

  The press section 4 presses each of the three webs with a press roller to increase the density of the paste portion and make the thickness uniform. The foil part press part 5 presses the aluminum foil, ie, the non-coated part, where the press part 4 is less affected by the press. Thereby, as for the aluminum foil which comprises a web, a coating part and a non-application part are rolled to the same extent, and a curve is suppressed.

  The film thickness measuring unit 6 measures the thickness of each web after rolling. The film thickness of the web is obtained by stretching the web on a predetermined roller (hereinafter referred to as “reference roller”) and measuring the distance between the optical displacement meter and the reference roller. Details of the film thickness measuring unit 6 will be described later.

The CPC unit 7 adjusts the conveyance position in the width direction of the web by adjusting the tension and conveyance speed of the three webs and correcting the meandering.
The 2nd slitter part 8 is equipped with a cutting blade, and cut | disconnects continuously in a longitudinal direction in the center position of an application part about each of three webs. In this embodiment, three cutting blades are provided, and three webs are cut simultaneously. Accordingly, the total number of webs output from the second slitter unit 8 is six. Further, the web is cut by the second slitter portion 8 so that the non-application portion is present only on one side in the width direction.
The ultrasonic cleaner 9 removes dust and the like from the surface of each of the six webs using ultrasonic waves.

The inspection unit 10 inspects each defect for each of the six webs. In addition, the inspection unit 10 prints a mark for displaying a defect on a location where it is determined that a defect has occurred in the process so far. The portion where this mark is printed is repelled in a later process and is not used in the product.
The winding part 11 winds each of the six webs separately in a roll shape.

[Thickness measuring device]
Then, the film thickness measuring apparatus 100 which comprises the film thickness measurement part 6 is demonstrated. As shown in FIG. 2, the film thickness measuring apparatus 100 includes a reference roller 31 that stretches and conveys the web 20, a drive device 32 that rotationally drives the reference roller 31, and an axial direction of the reference roller 31. The laser displacement meters 41, 42, 43, 44 arranged, a tension detector 46 that measures the tension of the web 20, and a control device 50 that acquires the measurement results of each measuring instrument and controls the driving device 32. ing.

  In the film thickness measuring apparatus 100, the four laser displacement meters 41, 42, 43, and 44 are fixed on the reference roller 31, and each laser displacement meter does not perform a scanning operation. The film thickness measuring apparatus 100 uses the web 20 after roll pressing as a specimen, and the thickness of the web 20 in the width direction can be regarded as constant. Therefore, measurement of the film thickness distribution in the width direction of the web 20 can be omitted.

  The web 20 as a test film is composed of a strip-shaped aluminum foil 21 and a paste layer 22 of a positive electrode active material applied on both surfaces of the aluminum foil 21. The web 20 is stretched around the reference roller 31 and is conveyed as the reference roller 31 is rotationally driven.

  In the film thickness measuring apparatus 100, a value obtained by measurement as follows is used as a measurement raw value. First, the laser displacement meter 41 projects the laser L1 toward the end of the reference roller 31 where the web 20 is not wound. Thereby, the distance from the surface of the reference roller 31 to the laser displacement meter 41 is obtained. Simultaneously with the distance measurement by the laser displacement meter 41, the laser displacement meter 42 is located on the center side in the axial direction of the reference roller 31 with respect to the laser displacement meter 41 (particularly the paste layer 22 is wound). The laser L2 is projected toward the (conveyed position). Thereby, the distance from the paste layer 22 surface to the laser displacement meter 42 is obtained. The difference between the measured value of the laser displacement meter 41 and the measured value of the laser displacement meter 42 becomes a measured raw value of the thickness of the web 20.

  In the film thickness measuring apparatus 100, a laser displacement meter 44 that measures the distance from the surface of the reference roller 31 is also provided at the other end of the reference roller 31. Furthermore, a laser displacement meter 43 that measures the distance from the surface of the paste layer 22 is also provided at the other end in the width direction of the paste layer 22. Thus, by providing two laser displacement meters for measuring the distance from the surface of the reference roller 31 and two laser displacement meters for measuring the distance from the surface of the paste layer 22, the inclination of the reference roller 31 or the web 20 is provided. Can be requested. Note that the laser displacement meters 41, 42, 43, and 44 of this embodiment may be general optical displacement meters.

  In the film thickness measuring apparatus 100 configured as shown in FIG. 2, when the web 20 is conveyed, it is affected by the web 20 floating due to air entrainment. That is, as shown in FIG. 3, with the rotation of the reference roller 31, air is caught in the gap between the reference roller 31 and the web 20. As a result, the air separates the web 20 from the reference roller 31 and causes the web 20 to float. Since the air entrainment amount increases as the speed of conveyance increases, the flying height A of the web 20 tends to increase as the conveyance speed of the web 20 increases. Of course, as the flying height A increases, the measurement error of the laser displacement meters 42 and 43 that measure the distance from the surface of the coating film 22 increases. The measurement error due to the air entrainment is one of the factors that deteriorate the film thickness measurement accuracy.

[Thickness measurement procedure]
Next, the procedure of the film thickness measurement process performed by the control device 50 of the film thickness measurement apparatus 100 will be described with reference to the flowchart of FIG. 4 and the graph of FIG. FIG. 5 shows the relationship (A) between the film thickness measurement value and time and the relationship (B) between the thin film conveyance speed and time. In this film thickness measurement process, a process is performed in consideration of the flying height A of the web 20 by air entrainment. In addition, this film thickness measurement process is an on-line measurement which performs a film thickness measurement, conveying the web 20 which is a test film.

  First, the conveyance of the web 20 is started, and the reference roller 31 is rotated at a low speed so that the conveyance speed of the web 20 becomes a predetermined conveyance speed v1 (an example of a second target speed) (S01). The conveyance speed v <b> 1 may be a value that can determine that the web 20 hardly floats and the influence on the film thickness measurement is small, and is defined in the control device 50 in advance. In this embodiment, for example, the conveyance speed v1 is set to 5 m / min. The conveyance speed v1 varies depending on the size and material of the web 20 and the reference roller 31.

  After the conveyance speed of the web 20 reaches v1, the web 20 is conveyed for a predetermined period at the conveyance speed v1, and the film thickness of the web 20 is measured during the low-speed conveyance. Then, the measured value is stored as a master value (S02). During low-speed conveyance, the amount of air entrained is small, and the flying height of the web 20 is small. Therefore, the measurement error is expected to be extremely small. Therefore, the value measured during low-speed conveyance is adopted as the master value.

  After acquiring the master value, the reference roller 31 is accelerated so as to reach a predetermined transport speed v2 (an example of a target speed) (S03). In this embodiment, for example, the reference roller 31 is driven so that the conveyance speed v2 is 100 m / min. The conveyance speed v2 is a high-speed conveyance speed that is a target speed for production of the conveyance device, and has high productivity, but the amount of air entrainment increases. That is, the measured value (measured raw value in FIG. 5) includes a large amount of floating due to air entrainment, and the measured value is larger than the actual film thickness.

  In particular, during the acceleration or a certain period from the end of the acceleration (range from t2 to t3 in FIG. 5), the tension of the web 20 is in an unstable state, and the measurement accuracy tends to deteriorate significantly due to air entrainment. is there. Therefore, based on the detection result of the tension detector 46, it is determined whether or not the tension of the web 20 is stabilized (S04). The tension detector 46 may be a general one that can detect the tension of the strip-shaped subject, and for example, a strain gauge is applicable. The tension stability can be determined, for example, by detecting the tension at a predetermined interval and determining whether or not the state where the difference between the current detection value and the previous detection value is smaller than the threshold value continues for a predetermined period or longer.

  During periods of unstable tension, the film thickness measurement accuracy is low, so it is expected that a good product will be misjudged as defective. Therefore, while it is determined that the tension is unstable (S04: NO), the master value acquired in S02 is used as a measurement value (S11). This avoids misjudgment.

  On the other hand, if it is determined that the tension is stable (S04: YES), the amount of change during high-speed conveyance is calculated (S05). That is, when it is determined that the tension has changed from an unstable state to a stable state (t3 in FIG. 5), the difference between the measured value of the film thickness at that timing and the master value is calculated. Then, the difference is stored as a change amount at the time of online measurement.

  FIG. 6 is an enlargement of the graph showing the relationship between the measured value of the film thickness shown in FIG. 5 and time, and s1 in FIG. 6 corresponds to the amount of change. This change amount s1 is considered to be a change amount caused by high-speed conveyance, mainly a flying height due to air entrainment. The change amount s1 includes a change over time due to the influence of the thermal expansion of the press roll (change in which the measured raw value in FIG. 5 gradually decreases), but the change over time that occurs until t3 when the tension is stabilized. Is very small compared to the flying height due to air entrainment, and has little effect on the calculated variation.

  After the change amount is calculated in S05, the measured value of the film thickness actually measured thereafter is corrected (S06). That is, the amount of change is subtracted from the value actually measured (measured raw value in FIG. 5), and the value (corrected value in FIG. 5) obtained by canceling the measurement error associated with the amount of change is output. Thereby, after the timing t3 when it can be determined that the tension is stabilized, a value excluding the influence of air entrainment can be set as the measurement value, and it can be expected that the measurement error is reduced.

  In addition, the measured value is a cyclic change due to the roll diameter variation of the press roll during the pressing process in the press unit 4 and the roll diameter variation of the backup roll in the die coating process (the measured raw value in FIG. To be affected. Therefore, the control device 50 may store the periodic change amount in advance. In this case, in the correction of S06, the periodic change amount may be acquired by timing t3, and the film thickness may be corrected in synchronization with the change amount due to the machining cycle. As a result, it is expected that a more appropriate change in film thickness over time can be measured based on the quality variation in the processing cycle (short distance) and the quality variation in the lot (long distance).

[Reference roller]
Next, the configuration of the reference roller 31 for further increasing the measurement accuracy will be described.

  In order to measure the film thickness using an optical displacement meter such as a laser displacement meter, it is necessary to accurately grasp the position of the reference roller 31. In this embodiment, the position of the reference roller 31 is measured by the laser displacement meters 41 and 44. For example, when using a laser displacement meter that detects the position of the measurement object by receiving diffuse reflection components, the reference roller 31 is used. If the surface of 31 is mirror-finished, the irregular reflection component tends to decrease and the measurement error tends to increase.

  Therefore, as the surface processing of the reference roller 31, a finishing process for reducing the mirror surface is performed on the roller surface. An example of the finishing process for reducing the mirror surface is anodizing of aluminum. In addition, the mirror surface can be reduced by roughening and matting or coloring. By reducing the mirror surface, irregular reflection components increase, and the position of the reference roller 31 can be measured with high accuracy.

  Further, as a finishing process for reducing the mirror surface, for example, a shot peening process (for example, WPC process) using fine particles may be performed. The shot peening treatment with fine particles can prevent the surface roughness from deteriorating while matt. Therefore, it can be expected to reduce the transfer scratches on the web 20. Further, in the shot peening process using fine particles, innumerable concave portions are formed on the surface, and the concave portions serve as air escape paths when the web 20 is conveyed. Therefore, the flying height of the web 20 due to air entrainment during high-speed conveyance can also be reduced. Therefore, it can be expected that both the position detection of the reference roller 31 and the position detection of the web 20 are highly accurate.

  As described in detail above, the film thickness measuring apparatus 100 according to the present embodiment measures the thickness of the web 20 (the film to be tested) online, and is transported at a low speed at a transport speed v1 that is less affected by air entrainment in advance. During the period, the master value is measured. Then, after reaching the conveyance speed v2 of the production target, the difference between the measured value of the film thickness of the online measurement and its master value is obtained as a change amount, and the measurement result of the film thickness obtained during the high-speed transfer is obtained as the change amount. It is corrected using. That is, the film thickness measuring apparatus 100 cancels the measurement error corresponding to the change amount by correcting the measurement raw value of the film thickness obtained during the high-speed conveyance by using the change amount. As a result, improvement in measurement accuracy can be expected.

  Moreover, the film thickness measuring apparatus 100 of this embodiment can perform all on-line by making the value measured in the low-speed conveyance period into a master value. In other words, it is not necessary to measure the film thickness offline. For this reason, there is no reduction in operating rate due to offline measurement.

  In the film thickness measuring apparatus 100 of this embodiment, the four laser displacement meters 41, 42, 43, and 44 are fixed on the reference roller 31, and each laser displacement meter does not perform a scanning operation. Therefore, the machine configuration necessary for the scanning operation is unnecessary, and the machine configuration is simple. In addition, when a scanning operation is necessary, it is difficult to achieve high accuracy because it is affected by scanning accuracy (for example, parallelism between a scanning line and a roller shaft). Has no such effect.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, in the embodiment, the manufacturing process of the electrode plate for the positive electrode has been described, but the electrode plate for the negative electrode may be used. Further, the present invention is not limited to the manufacturing process of battery electrode plates, and can be widely applied to the use of measuring the thickness of a thin film formed on a strip-shaped substrate.

  In the embodiment, the master value is acquired by online measurement of the web 20 during low-speed conveyance, but the present invention is not limited to this. For example, the film thickness measured off-line may be stored as a master value. In this case, the low-speed transport period at the transport speed v1 is unnecessary. In addition, since the offline measurement is not affected at all by air entrainment, a master value with higher accuracy can be obtained than in the embodiment in which the master value is acquired by online measurement.

  In the embodiment, the film thickness is a master value until the tension stabilizes at the acceleration of measurement start. However, it is expected that the tension becomes unstable even at the time of deceleration after the measurement. . For this reason, at the end of measurement, after determining that the tension has changed from a stable state to an unstable state, the master value may be substituted for the measured value.

6 Film thickness measuring unit 20 Web (film to be tested)
21 Aluminum foil 22 Paste layer 31 Reference roller 32 Driving device 41, 44 Laser displacement meter (first displacement meter)
42, 43 Laser displacement meter (second displacement meter)
46 Tension detector 50 Control device 100 Film thickness measuring device

Claims (13)

In a film thickness measuring device that measures the thickness of a strip-shaped test film,
A first displacement meter that measures a distance from a surface of a reference roller that is a roller that stretches the test film; and a second displacement meter that measures a distance from the surface of the test film that is stretched by the reference roller; An on-line measuring unit that calculates the thickness of the test film based on the measurement results of the first displacement meter and the second displacement meter;
A master acquisition unit that acquires a master value serving as a reference for the thickness of the test film before the transport speed of the test film reaches the target production speed;
A change amount calculation unit that calculates the difference between the measurement value in the online measurement unit and the master value as a change amount after the acquisition of the master value and after the conveyance speed of the test film reaches the target speed When,
A correction unit that corrects the measurement value obtained by the online measurement unit using the variation calculated by the variation calculation unit;
A film thickness measuring apparatus comprising: In the film thickness measuring device according to claim 1,
The master acquisition unit measures the measurement obtained by the online measurement unit during a period in which the transport speed of the test film reaches the target speed and is a second target speed that is slower than the target speed. A film thickness measuring apparatus for acquiring a value as a master value. In the film thickness measuring device according to claim 1,
The master acquisition unit acquires the thickness of the test film measured when offline as a master value. In the film thickness measuring device according to any one of claims 1 to 3,
The change amount calculation unit calculates the change amount after the start of conveyance of the test film and after the tension of the test film becomes constant. In the film thickness measuring device according to claim 4,
After the acquisition of the master, a second correction unit that corrects the master value as the thickness of the test film is provided until the tension of the test film becomes constant. measuring device. In the film thickness measuring device according to any one of claims 1 to 5,
The correction unit detects the amount of movement of the reference roller in the conveyance direction, and corrects it in synchronization with the processing cycle of the upper roller positioned upstream of the reference roller in the conveyance direction of the film to be tested. A film thickness measuring device characterized by the above. In the film thickness measuring device according to any one of claims 1 to 6,
The first displacement meter is an optical displacement meter,
The film thickness measuring apparatus according to claim 1, wherein the reference roller is subjected to a finishing process to reduce a mirror surface. In the film thickness measuring device according to claim 7,
The film thickness measuring apparatus, wherein the finishing process is a process of projecting fine particles onto the surface of the reference roller. In a film thickness measuring method for measuring the thickness of a test film having a strip shape,
The first displacement meter measures the distance from the reference roller surface, which is a roller for stretching the test film, and the second displacement meter measures the distance from the test film surface stretched on the reference roller. An on-line measurement step of measuring a distance and calculating the thickness of the test film based on the measurement results of the first displacement meter and the second displacement meter;
A master acquisition step of acquiring a master value serving as a reference for the thickness of the test film before the transport speed of the test film reaches the target production speed;
A change amount calculating step for calculating a difference between the measured value by the online measuring step and the master value as a change amount after the acquisition of the master value and the transport speed of the test film reaches the target speed; ,
A correction step for correcting the measurement value in the online measurement step using the variation calculated in the variation calculation step;
The film thickness measuring method characterized by including. In the film thickness measuring method according to claim 9,
In the master acquisition step, the on-line measurement step was performed during a period in which the transport speed of the test film reached the second target speed that was lower than the target speed before reaching the target speed. A film thickness measuring method, wherein a measured value is acquired as a master value. In the film thickness measuring method according to claim 9,
In the master acquisition step, the thickness of the film to be measured measured offline is acquired as a master value. In the film thickness measuring method according to any one of claims 9 to 11,
In the change amount calculating step, the change amount is calculated after the start of conveyance of the test film and after the tension of the test film becomes constant. In the film thickness measuring method according to claim 12,
The film thickness includes a second correction step of correcting the master value as the thickness of the test film after the acquisition of the master and until the tension of the test film becomes constant. Measuring method.

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