JP2022087039A - Color measuring device and method of manufacturing sheet - Google Patents

Abstract

To provide a color measuring device by which a tendency of a color tone of sheet can be managed in-line and which is excellent in color measurement accuracy, and also to provide a method of manufacturing the sheet using the same.SOLUTION: A color measuring device includes: light irradiation means for irradiating a conveying sheet with light, light receiving means for receiving at least one of the transmitted light transmitted through the conveying sheet and the reflected light reflected by the conveying sheet; and spectroscopic means for detecting the color by acquiring an optical spectrum of the light received by the light receiving means. The light irradiation means and the light receiving means include thickness measuring means. The light irradiation means, the light receiving means and the thickness measuring means reciprocate in parallel to a width direction of the conveying sheet.SELECTED DRAWING: Figure 1

Description

The present invention relates to a color measuring device capable of in-line evaluation of color tone uniformity of a sheet and color tone control based on thickness, and a method of manufacturing a sheet using the same.

In recent years, sheets such as thermoplastic resin films have been used in various fields, especially for optical applications such as flat panel displays and touch panels, decorative applications such as mirror displays, smartphones and automobile emblems, and UV cut and heat ray cut. In sheets used for wavelength selection applications such as blue light cut, uniformity of color tone is one of the important physical properties from the viewpoint of the quality of the equipment on which they are mounted and the color tone required for the sheet. Therefore, in the film forming process of such a sheet, in-line evaluation of the color tone of the sheet and management of the tendency are possible in terms of quality pass / fail judgment, grasp of abnormality occurrence, and early response to abnormality. is important. It is also important to be able to evaluate the color tone of the entire length and width of the sheet in order to reduce the outflow of defective products and improve the quality.

From the above background, various methods have been used to evaluate the color tone of the sheet inline. As such a method, for example, a method of installing several color sensors having independent color measuring mechanisms in the width direction and displaying a color difference from a reference color tone value (Patent Document 1), and an imaging spectroscope are used. A method of identifying the color tone of a pattern in a designated range of a sheet (Patent Document 2) and the like can be mentioned. In addition, there is a technique that not only makes a pass / fail judgment in the film forming process but also manages the color tone tendency in-line, and enables quick grasping of the situation and response in the event of an abnormality (Patent Document 3).

Japanese Unexamined Patent Publication No. 06-41864. Japanese Unexamined Patent Publication No. 2006-82501 Japanese Unexamined Patent Publication No. 2016-70729

However, in the methods of Documents 1 and 2, although the pass / fail judgment of the color tone can be performed in-line, it is difficult to manage the tendency of the color tone in the process. Further, in the method of Patent Document 3, since the color sensors installed at a plurality of locations are used, the color tone difference due to the characteristic difference of each color sensor becomes a problem, and the light amount difference due to the consumption of the light source device and the influence of the received disturbance light are affected. Therefore, there is a problem that the accuracy is not stable depending on the color measurement location and time. In addition, when the color difference becomes a problem, it is difficult to investigate the specific cause and take timely measures.

The present invention overcomes the above-mentioned problems of the prior art, can manage the tendency of the color tone of the sheet in-line, and further, by simultaneously measuring the thickness of the sheet that affects the color tone, when the color tone difference becomes a problem. It is an object of the present invention to provide a color measuring device capable of investigating the cause of the above and a method of manufacturing a sheet using the same.

The color measuring device for a sheet-like object of the present invention that solves the above problems has the following configuration.
(1) A light irradiating means for irradiating a transport sheet with light, a light receiving means for receiving at least one of the transmitted light transmitted through the transport sheet and the reflected light reflected by the transport sheet, and the light receiving means. A spectroscopic means for detecting a color by acquiring a spectral spectrum of the light is provided, the light irradiation means and the light receiving means are provided with a thickness measuring means, and the light irradiation means, the light receiving means, and the thickness measurement are provided. A color measuring device, characterized in that the means reciprocates in parallel with the width direction of the transport sheet.
(2) The color measuring device according to (1), characterized in that the color is measured at regular intervals in the width direction of the transport sheet.
(3) The light irradiating means, the light receiving means, and the thickness measuring means perform zero point correction at a timing outside the widthwise end of the transport sheet, (1) or (2). The color measuring device described in.
(4) Claims 1 to 1, wherein at least one of the range within 30 cm from the center of the light source of the light irradiation means and the range within 30 cm from the center of the light irradiation point of the light receiving means is dark. The color measuring device according to any one of 3.
(5) The color measuring device according to any one of (1) to (4), which comprises a calculation means for obtaining a color tone value from the spectral spectrum.
(6) The color measuring device according to (5), further comprising a display means for displaying the color tone value in real time at at least one of the color measurement value trend and the saturation distribution.
(7) It is characterized in that the transport sheet is provided with a verification means for verifying whether or not the color tone value is included in the control color tone value range on a straight line parallel to the longitudinal direction arbitrarily drawn, (5) or. The color measuring device according to (6).
(8) The color measuring device according to (7), wherein the verification means includes an alarm function for issuing an alarm when a color tone value outside the controlled color tone value range is observed.
(9) The thickness measuring means measures the thickness value at a position where the distance from the color measuring point is 0 mm or more and 500 mm or less, and displays the thickness value trend on the display means in real time. The color measuring device according to any one of (6) to (8).
(10) The color measuring device according to (9), characterized in that the correlation between the color measuring trend and the thickness value trend is obtained.
(11) The reciprocating light irradiating means, the light receiving means, and the driving part and the traveling part of the thickness measuring means are wear-resistant members, and the dynamic friction coefficient μd between the members in contact during operation is 0.1 ≦ μd. The color measuring device according to any one of (1) to (10), which is a member satisfying <0.3.
(12) A method for manufacturing a sheet, which comprises performing color tone control and thickness control of a conveyed sheet using any of the color measuring devices (1) to (11).

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a color measuring device having the following two features (I) and (II), and a method for manufacturing a sheet using the same.
(I) It is possible to reduce the color measurement error depending on the color measurement location and time, evaluate the color tone in the sheet width direction inline with higher accuracy, and manage the color tone tendency more accurately in inline.
(II) Correlate the color tone spot with the thickness, adjust the thickness so that the target color tone is obtained, distinguish the cause of the color tone spot by thickness or others, and detect the cause of the color tone spot at an early stage. It is possible.

It is a schematic view when the color measuring apparatus which concerns on one Embodiment of this invention is observed from the longitudinal direction. FIG. 5 is a schematic view of the color measuring device and the transport sheet shown in FIG. 1A when observed from a direction perpendicular to the transport sheet surface. It is a schematic diagram which shows the color measurement position in the transport sheet when the color measurement is performed by the aspect of FIG. It is a schematic diagram which shows an example of a colorimetric value trend. It is a schematic diagram which shows an example of a coloring distribution. It is a schematic diagram which shows the color measuring apparatus of the aspect A of FIG. 1, which includes the calculation means, the display means, and the verification means. It is a flowchart which shows the color measuring procedure in the color measuring apparatus of the aspect of FIG. This is an example of a pass / fail determination result displayed on the first display unit of the color measuring device according to the aspect of FIG. It is a schematic diagram which shows the multipoint simultaneous color measuring apparatus used in the comparative example 1. FIG.

Hereinafter, the color measuring device of the present invention will be described in detail. The color measuring device of the present invention includes a light irradiating means for irradiating a transport sheet with light, a light receiving means for receiving at least one of the transmitted light transmitted through the transport sheet and the reflected light reflected by the transport sheet, and the above-mentioned A spectroscopic means for detecting color by acquiring a spectral spectrum of light received by a light receiving means is provided, the light irradiating means and the light receiving means are provided with a thickness measuring means, and the light irradiating means and the light receiving means, The thickness measuring means reciprocates in parallel with the width direction of the transport sheet. Here, color measurement means acquiring a spectral spectrum to obtain an index representing color. Examples of the index representing the color include a color tone value described later.

It is important that the color measuring device of the present invention includes a light irradiating means for irradiating the transport sheet with light. Here, the sheet refers to a sheet-like flexible continuous medium, and specific examples thereof include a thermoplastic resin film and the like. The transport sheet is a sheet that runs in the manufacturing process before it becomes a final product. The light irradiation means is a device provided with a light source that irradiates the transport sheet with light.

In the color measuring device of the present invention, the light irradiation means is arranged on one side of the transport sheet (for example, the upper side or the lower side when the transport sheet is horizontal) so as not to come into contact with the transport sheet. This light irradiation means plays a role of irradiating one side of a transport sheet, which is a color measurement object, with light to generate transmitted light and reflected light necessary for color measurement. Normally, when the light emitted from the light irradiating means reaches the transport sheet, transmitted light transmitted through the transport sheet and reflected light reflected by the transport sheet are generated. Color measurement by the color measuring device of the present invention requires a step in which a light receiving means described later receives transmitted light or reflected light.

The light source used as the light irradiation means is not particularly limited as long as it can obtain the transmitted light and reflected light required for color measurement, and various light sources such as halogen lamps and tungsten lamps are used depending on the color to be measured. Can be used. However, since there is a peak in the visible light region and a sufficient amount of light can be secured even with a small light source, it is preferable to use a halogen lamp from the viewpoint of being suitable for analysis of a wide range of color tones.

It is important that the color measuring device of the present invention includes a light receiving means that receives at least one of the transmitted light transmitted through the transport sheet and the reflected light reflected by the transport sheet. In the color measuring device of the present invention, the light receiving means is arranged on one side of the transport sheet (for example, the upper side or the lower side when the transport sheet is horizontal) so as not to come into contact with the transport sheet. Normally, when the transmitted light is used for color measurement, the light receiving means is arranged on the side opposite to the surface where the light irradiation means is located, and when the reflected light is used for color measurement, the light receiving means is arranged on the surface side where the light irradiation means is located. .. When both transmitted light and reflected light are used for color measurement, light receiving means are arranged on both surface sides.

This light receiving means plays a role of receiving transmitted light and reflected light. The color measurement by the color measuring device of the present invention requires a step in which the spectroscopic means described later acquires the spectral spectrum of the light that has reached the light receiving means. The light receiving means is not particularly limited as long as it has a function of receiving transmitted light or reflected light, and for example, various lenses and the like can be used.

It is important that the color measuring device of the present invention includes a spectroscopic means for detecting a color by acquiring a spectroscopic spectrum of light received by the light receiving means. The spectroscopic means is arranged on the path of the light passing through the light receiving means, in other words, at a position where the light passing through the light receiving means can be incident. This spectroscopic means has a role of separating the light received by the light receiving means for each wavelength band to acquire a spectral spectrum and detecting the color of the carrier sheet from the spectral spectrum.

The spectroscopic means is not particularly limited as long as it is a device capable of spectroscopy, and for example, an imaging spectroscope provided with a slidable slit or a color sensor can be preferably used. When such a spectroscope is used, the spectroscopic spectrum can be obtained by splitting the light received by the light receiving means into a desired wavelength band with a slidable slit and then incorporating the light into the imaging spectroscope main body.

In the color measuring device of the present invention, it is important that the light irradiating means and the light receiving means are provided with the thickness measuring means of the transport sheet from the viewpoint of controlling the thickness at the same time as the color tone with high accuracy. Here, the thickness of the transport sheet means the total thickness of the transport sheet. When the color tone of the transport sheet changes depending on the thickness (for example, heat ray reflection and blue light, and a multilayer laminated film that selectively reflects and cuts visible light), the correlation between the color tone and the thickness of the sheet is evaluated. In terms of quality control, it is important to control the color tone according to the thickness based on the correlation between the two. The thickness measuring means is not particularly limited, but a method of irradiating the transport sheet with radiation and obtaining the thickness from the amount of attenuation when passing through the transport sheet can be used. The details will be described later.

However, when the color measuring device and the thickness measuring means are installed at a distance from each other in the traveling direction of the transport sheet, or when measuring different positions in the width direction of the transport sheet, the measurement points of both are different and the color tone is different. The correct correlation between the value and the thickness value may not be obtained. As a result, when a value deviating from the target color tone value is observed, it becomes difficult to adjust the thickness of the transport sheet to reduce the color tone unevenness.

On the other hand, when the light irradiating means and the light receiving means constituting the color measuring device are provided with the thickness measuring means, the color tone measuring point and the thickness measuring point can be brought closer to each other. By adopting such an aspect, it is possible to correctly collect the correlation between the color tone and the thickness, so that it is possible to set the target thickness and manage the color tone more accurately when adjusting to the target color tone. It becomes.

Further, since the color tone changes due to a factor other than the thickness of the transport sheet, by using the color measuring device of such an embodiment, the color tone change of the transport sheet may be due to the change in the thickness, or another factor (for example, transport). It is possible to distinguish whether the sheet is based on the thickness, thickness ratio, refractive index difference, etc. of each layer constituting the sheet. As a result, it is possible to identify the cause of the color tone abnormality in a shorter time and with higher accuracy.

From the above viewpoint, it is preferable that the color measuring point and the thickness measuring point are as close as possible. Specifically, the thickness measuring means determines the thickness value at the position where the distance from the color measuring point is 0 mm or more and 500 mm or less. It is preferable to measure. Here, "measuring the thickness value at a position where the distance from the color measurement point is 0 mm" means that the color measurement point and the thickness measurement point are exactly the same, and this embodiment is the most ideal. It becomes an aspect.

In the color measuring device of the present invention, it is important that the light irradiating means, the light receiving means, and the thickness measuring means reciprocate in parallel with the width direction of the conveying sheet from the viewpoint of evaluating the color tone of the conveying sheet over a wide range. .. Here, the width direction of the transfer sheet means a direction orthogonal to the traveling direction (longitudinal direction) of the transfer sheet in the surface of the transfer sheet. By adopting such an aspect, not only the color measurement point in the longitudinal direction can be changed by the traveling of the transfer sheet, but also the color measurement point in the width direction can be changed, so that the transfer sheet can be two-dimensionally changed. Color measurement and thickness measurement are possible.

The movable range of the light irradiating means, the light receiving means, and the thickness measuring means is not particularly limited as long as they reciprocate in parallel with the width direction of the conveying sheet. However, from the viewpoint of measuring the color over the entire width of the transport sheet, it is preferable to reciprocate in a section from the outside of one widthwise end to the outside of the other widthwise end. Further, by adopting such an embodiment, when the light irradiation means and the light receiving means are not on the sheet surface, that is, when they are located at both ends of the movable range, for example, the zero point correction described later is performed to perform color measurement unevenness. It is also possible to maintain the color measurement accuracy while reducing the thickness measurement unevenness.

Further, the relative positional relationship between the light irradiating means and the light receiving means is preferably kept constant even during the reciprocating motion from the viewpoint of color measurement accuracy, and the same applies to the thickness measuring means. With such an embodiment, the transmitted light and the reflected light are continuously incident on a certain position of the light receiving means, and the color measurement accuracy and the thickness measurement accuracy can be maintained high. As a method of keeping the relative positional relationship between the light irradiation means and the light receiving means constant, there is a method of moving them in the same direction and at the same speed.

From the viewpoint of stabilizing the color measurement accuracy, the color measuring device of the present invention has at least one of a range within 30 cm from the center of the light source of the light irradiating means and a range within 30 cm from the center of the light irradiating point of the light receiving means. It is preferably dark, and more preferably both of these areas are dark. The range within 30 cm from the center of the light source of the light irradiation means means the range in which the distance from the center of the light source is within 30 cm when the light irradiation means is observed from the direction facing the traveling direction of the light emitted by the light source. .. The range within 30 cm from the center of the light irradiation point of the light receiving means is the range within 30 cm from the center of the light irradiation point of the light receiving means when the light receiving means is observed from the traveling direction of the light emitted by the light source. Say. The dark color means a color that absorbs at least one color of 70% or more and less than 100% when the light emitted from the light source is divided into the three primary colors of light, red, green, and blue. Specific examples of the dark color include black, brown, brown, dark blue, and dark gray.

"The area within 30 cm from the center of the light source of the light irradiation means is dark" means that the area within 30 cm from the center of the light source of the light irradiation means is regarded as a two-dimensional plane perpendicular to the traveling direction of the light. When the total area is 100%, it means that 80% or more and less than 100%, preferably 99.5% or less, is a dark color. Here, the upper limit is set to less than 100% because the light source portion cannot be darkened. "The range within 30 cm from the center of the light irradiation point of the light receiving means is dark color" can be interpreted in the same manner as above, and the upper limit of the area ratio of the dark color portion in the light receiving means is set to less than 100%. This is because the light irradiation point cannot be darkened.

The method of darkening at least one of the range within 30 cm from the center of the light source of the light irradiation means and the range within 30 cm from the center of the light irradiation point of the light receiving means is not particularly limited as long as the effect of the present invention is not impaired. For example, a method of using a dark color member in these ranges or painting these ranges in a dark color can be mentioned. If the target color measurement wavelength is infrared or ultraviolet, use a material that absorbs infrared rays or ultraviolet rays in these ranges, or use a coating material that absorbs infrared rays or ultraviolet rays in these ranges. It is also possible to paint with. Further, from the viewpoint of suppressing a decrease in measurement accuracy due to light other than the light emitted by the light irradiating means (hereinafter, may be referred to as external light), the surface roughness in these ranges is increased to diffusely reflect the external light. Therefore, it is also preferable to suppress the amount of external light that reaches the light receiving means. By making such a mode, it is possible to reduce the reflection of external light on the surface of these ranges and incident on the light receiving portion, so that it is possible to reduce color measurement unevenness and improve color measurement accuracy. ..

Hereinafter, the positional relationship and movement of each means constituting the color measuring device of the present invention will be specifically described with reference to the drawings. FIG. 1 is a schematic view of a color measuring device according to an embodiment of the present invention when observed from the longitudinal direction. Note that A in FIG. 1 represents a color measuring device of a type in which the light receiving means receives the transmitted light, and B in FIG. 1 represents a color measuring device of the type in which the light receiving means receives the reflected light.

In the color measuring device 1 of the embodiment shown in FIG. 1A, the light irradiating means 2 and the spectroscopic means 4 integrated with the light receiving means 3 are located on the upper surface side and the lower surface side thereof without contacting the transport sheet 5. do. Then, the spectroscopic means 4 including the light irradiating means 2 and the light receiving means 3 reciprocate along the rail 7 attached to the frame 6 in parallel with the width direction of the transport sheet 5. When the irradiation light 9 emitted by the light source 8 of the light irradiation means 2 reaches the transport sheet 5, transmitted light 10 and reflected light 11 are generated, and the transmitted light 10 is taken into the spectroscopic means 4 via the light receiving means 3. The transmitted light 10 captured in the spectroscopic means 4 is separated into a desired wavelength band by a movable slit 12 provided in the spectroscopic means 4 and taken into the main body 13 of the spectroscopic means, where the light is captured on the transport sheet 5. A spectroscopic spectrum at the light irradiation point is obtained.

As described above, a halogen lamp can be preferably used as the light source 8, various lenses can be preferably used as the light receiving means 3, and an imaging spectroscope (with a slit 12) can be preferably used as the spectroscopic means 4, and the slit 12 and the spectroscope can be used. A color sensor (not shown) may be arranged between the main bodies 13 of the means according to the color tone to be detected. The same applies to the color measuring device of the aspect shown in B of FIG. 1 to be described later.

In the color measuring device 1 of the embodiment shown in FIG. 1B, the spectroscopic means 4 integrated with the light irradiating means 2 and the light receiving means 3 is located on the lower surface side of the conveying sheet 5 without coming into contact with the frame. It reciprocates along a rail 7 attached to 6 in parallel with the width direction of the transport sheet 5. When the irradiation light 9 emitted by the light source 8 of the light irradiation means 2 reaches the transport sheet 5, transmitted light 10 and reflected light 11 are generated, and the reflected light 11 is taken into the spectroscopic means 4 via the light receiving means 3. The reflected light 11 captured in the spectroscopic means 4 is separated into a desired wavelength band by the movable slit 12 provided in the spectroscopic means 4 and taken into the main body 13 of the spectroscopic means, where the light is captured on the transport sheet 5. A spectroscopic spectrum at the light irradiation point is obtained.

Further, the color measuring device 1 shown in FIGS. 1A and 1B also includes a thickness measuring means. The thickness measuring means exists as a radiation irradiation means A having a radiation source on the upper surface side thereof and a radiation light receiving means B having an ion chamber on the lower surface side without contacting the transport sheet 5 (radiation irradiation means A and radiation receiving means). The position of B may be reversed.) Then, the radiation irradiating means A reciprocates along the rail 7 together with the light irradiating means 2 and the radiation receiving means B together with the spectroscopic means 4. When the radiation (β rays or the like) emitted from the radiation source of the irradiation means passes through the transport sheet 5, the radiation dose thereof is attenuated, and the passed radiation is taken into the ion chamber via the radiation receiving means. The radiation taken into the ion chamber is ionized by the electrodes provided in the ion chamber, and an ionizing current is generated according to the ionization energy. By detecting the ionizing current with an electrometer (not shown) and measuring the electromotive voltage, the radiation dose incident on the radiation receiving means B is measured to obtain the attenuated radiation dose, and the conveyed sheet 5 is obtained from the attenuated radiation dose. Find the thickness of.

The radiation source of the irradiation means A is not particularly limited because the appropriate material changes depending on the thickness, material, density, etc. of the transport sheet to be measured, but is not particularly limited, for example, Kr (Krypton), Pm (Promethium), Sr (Strontium). Etc. can be selected.

It is also preferable that the thickness measuring means is interlocked with the thickness adjusting means and the thickness adjusting means is automatically controlled from the measurement result. Taking the production of a biaxially oriented film by the sequential biaxial stretching method as an example, the amount of polymer discharged from the mouthpiece, the slit gap of the mouthpiece, the rotation speed of the cast drum, the rotation speed of the stretching roll for longitudinal stretching, and the distance between the clips for transverse stretching. The thickness can be adjusted by the width and the like, and the means for adjusting these is called the thickness adjusting means. By taking such a mode, when the thickness (and color tone) of the conveyed sheet changes during manufacturing, it is easy to automatically control the thickness adjusting means from the thickness measurement result and keep the thickness and color tone constant. Become.

From the viewpoint of stabilizing the color measurement accuracy, the color measuring device of the present invention preferably measures colors at regular intervals in the width direction of the transport sheet. Here, "color measurement at regular intervals in the width direction of the transport sheet" means that color measurement is performed so that the length in the width direction between the two color measurement points is constant. At this time, assuming that the total length in the width direction of the transport sheet is 100%, if the above requirements are satisfied in the range of 70% or more and 100% or less, "color measurement is performed at regular intervals in the width direction of the transport sheet. It can be regarded as a thing. At this time, if the part to be discarded (discarded part) that does not become the final product is known in advance at the stage of the transport sheet, the calculation within the range satisfying the above requirements is the part excluding the discarded part from the transport sheet. It is assumed that the length in the width direction of is 100%. It is more preferable that the thickness is measured in the same manner from the viewpoint of improving the measurement accuracy.

By adopting such an aspect, it is possible to measure the color of the conveyed sheet (particularly the part that becomes the final product) by reducing the bias of the color measurement point, and thus it is possible to predict the color tone unevenness of the entire sheet finally obtained. be able to. Therefore, it is possible to detect abnormal color tone at an early stage, and by taking appropriate improvement measures for it, it is possible to keep the production of the final product with poor color tone low. The means for measuring the color at regular intervals in the width direction of the transport sheet is not particularly limited as long as the effect of the present invention is not impaired. A method of making the time interval for performing color constant is mentioned.

Next, when the color measuring device of the present invention is used to measure colors at regular intervals in the width direction of the transport sheet, the color measuring points will be specifically described with reference to FIGS. 2 and 3. .. FIG. 2 is a schematic view of the color measuring device and the transport sheet shown in FIG. 1A when observed from a direction perpendicular to the transport sheet surface (however, the upper part of the frame and the rail on which the light irradiation means travels are shown. do not do.). FIG. 3 is a schematic view showing the color measurement position on the transport sheet when the color measurement is performed in the aspect of FIG.

As shown in FIG. 2, the transport sheet 5 is transported in the longitudinal direction 14, and is not shown in FIG. 2 because it is located on the opposite side of the light irradiation means 2 and the light receiving means (the transport sheet is sandwiched between the light irradiation means 2). ) Reciprocates in the color measuring device 1 in parallel with the width direction 15 from the outside of one width direction end portion of the transport sheet 5 to the outside of the other width direction end portion. At this time, since the point at which the light irradiating means 2 irradiates the light is the color measuring point, the light when the moving speeds of the light irradiating means 2 and the light receiving means are constant and the light irradiating means 2 is on the transport sheet 5. By setting the time interval for irradiating the light to be constant, it is possible to "measure the color at a constant interval in the width direction of the transport sheet".

The transport speed of the transport sheet 5 when passing through the color measuring device 1 is usually constant as long as the position of the color measuring device 1 in the longitudinal direction 14 does not change. Therefore, the positions of the color measurement points when the color measurement is performed in the aspect of FIG. 2 are as shown in FIG. More specifically, under the condition that the transport sheet 5 is transported in the longitudinal direction 14 at a constant speed, the light irradiation means and the light receiving means (both not shown in FIG. 3) are parallel to the width direction 15 at a constant speed. If the time interval for irradiating the light when the light irradiating means is on the transport sheet 5 is constant, the color measuring points 16 are defined in the order indicated by the white arrows in FIG. 3, and each color measuring point is defined. The length 17 in the width direction between the spaces is also constant. The length 17 in the width direction between the color measurement points is not particularly limited as long as the effect of the present invention is not impaired, and is appropriately determined according to the width of the transport sheet 5, the width of the sheet assumed as the final product, and the like. Can be determined.

The color measuring device of the present invention has zero at the timing when the light irradiation means, the light receiving means, and the thickness measuring means are outside the widthwise end of the transport sheet from the viewpoint of reducing the color measurement and the thickness measurement error that occur over time. It is preferable to perform point correction. Here, the zero point means a value when the color is measured in a state where the transport sheet, which is the object of color measurement and thickness measurement, is not irradiated with light and radiation. Zero point correction is to reset the zero point by performing color measurement and thickness measurement in a situation where a color measuring device including a thickness measuring means is in operation and the transport sheet is not irradiated with light and radiation. Say.

More specifically, in the case of color measurement, the spectral spectrum obtained under such conditions is set to 100% at all wavelengths, and the L * value, a * value, and b * value, which will be described later, are set to 100 in order. It means to set 0 and 0. Normally, the zero point of a spectroscope used as a spectroscopic means may deviate from the value set before use due to long-term use of the device, so it is possible to maintain color measurement accuracy by appropriately correcting the zero point. can. Further, in the case of thickness measurement, it means that the ionizing current and electromotive voltage of the radiation obtained under such conditions are set to a thickness of 0 μm. Normally, the radiation source used as a thickness measuring means is measured in a large thickness due to the decrease in the irradiation amount of radiation with the long-term use of the device (apparently, it is observed that the amount attenuated by the transport sheet is increasing). However, in reality, the amount of radiation itself is reduced.) Therefore, the thickness measurement accuracy can be maintained by appropriately correcting the zero point. In the present invention, if the zero point correction is performed for at least one of the color measurement and the thickness, it is considered that the zero point correction has been performed.

Color measurement in a state where the transport sheet is not irradiated with light means that if the light receiving means is a color measuring device that receives transmitted light, the transport sheet does not exist between the light irradiation means and the light receiving means. If the color measuring device is a color measuring device in which the light receiving means receives the reflected light, it exists at a position on the extension of the width direction of the transport sheet and does not come into contact with the transport sheet, and is parallel to the transport sheet surface. Color measurement performed by irradiating a standard reflector with light. The standard reflector is located at a position where light from the light irradiation means is not irradiated except at the timing of zero point correction (for example, outside the reciprocating motion range between the light irradiation means and the light receiving means, or inside the housing of the light irradiation means or the light receiving means. ), It is preferable to provide it in a manner that allows it to be retracted. The standard reflector can be appropriately changed depending on the nature of the reflected light incident on the light receiving means, for example, a mirror or the like when the specular reflected light is incident, and a standard white plate (for example, when the diffuse reflected light is incident). Barium sulfate, polytetrafluoroethylene (PTFE), ceramic, etc.) can be preferably used.

At "timing when the light irradiating means, the light receiving means, and the thickness measuring means are outside the widthwise end of the transport sheet", the light (or standard reflection) emitted by the light irradiating means while the sheet production line is operating. (Reflected light from an object) can reach the light receiving means without hitting the transport sheet (the same applies to the radiation emitted by the irradiation means). Therefore, by performing zero point correction at such timing, the light amount of the light source decreases due to wear due to continuous use, the change in the light receiving amount due to the ambient light amount that becomes a disturbance, and the radiation source without interrupting the production of the sheet. It is possible to set a zero point that appropriately reflects changes in the radiation dose due to a decrease in the radiation dose. As a result, the color measurement and thickness measurement accuracy of the color measuring device can be maintained high for a long period of time.

As a method of recognizing that the light irradiation means, the light receiving means, and the thickness measuring means are outside the widthwise end of the sheet, the reciprocating motion range of the light irradiation means, the light receiving means, and the radiation irradiation means is previously set in the width direction of the sheet. A method of setting the entire length to be included, or a method of widening the reciprocating motion range of the light irradiation means, the light receiving means, and the irradiation means beyond the maximum width of the sheet that can be conveyed by the transfer device can be used.

The color measuring device of the present invention preferably includes a calculation means for obtaining a color tone value from the spectral spectrum from the viewpoint of quantifying the color from the spectral spectrum obtained by the spectral means and facilitating the evaluation of color unevenness of the conveyed sheet. The color tone value means the L * value, the a * value, and the b * value in the CIE1976L * a * b * color system. Here, the L * value represents the brightness of the color from 0 to 100, and the brighter the color, the larger the L * value. The a * value represents the tint in the red and green directions in the range of -100 to +100, and the stronger the redness, the larger the value in the + direction, and the stronger the greenishness, the larger the value in the-direction. The b * value represents the tint in the yellow and blue directions in the range of -100 to +100, and the stronger the yellowness, the larger the value in the + direction, and the stronger the bluishness, the larger the value in the-direction.

By the calculation means in the color measuring device of the present invention, the C light source specified in JIS Z 8722 (2009) and the two-degree field tristimulus values X, Y, Z are acquired from the spectroscopic spectrum, and the JIS Z 8730 (2009) is obtained. The color tone values (L * value, a * value, b * value) can be calculated from the C light source and the two-degree field tristimulus values X, Y, and Z using the specified calculation formula. As long as the color tone value can be calculated by the above method, the type of the calculation means is not particularly limited, and a known computer or software can be used in an appropriate combination.

The installation position of the arithmetic means in the color measuring device of the present invention is not particularly limited as long as it is installed in a manner capable of acquiring spectral spectrum data from the spectroscopic means constituting the color measuring device. In order to acquire the spectral spectrum data from the spectroscopic means, a known method such as a cable capable of data communication or a wireless LAN can be used. Further, it is preferable that the calculation means has a function of converting the color tone value data into a color measurement value trend or a saturation distribution, which will be described later, from the viewpoint of facilitating grasping the abnormality of the color tone of the transport sheet.

From the viewpoint of early grasping of abnormalities, the color measuring device of the present invention preferably includes a display means for displaying a color tone value in real time on at least one of a color measurement value trend and a saturation distribution. Here, the color measurement value trend is defined by any one of "time or the position in the width direction of the color measurement point on the transport sheet" and "at least one of L * value, a * value, and b * value" on the horizontal axis. A chart diagram showing the other as the vertical axis. The saturation distribution is a scatter plot in which one of the a * value and the b * value obtained in an arbitrarily determined period is represented by the horizontal axis and the other is represented by the vertical axis. From the same viewpoint, it is also preferable to display the thickness value trend on the display means in real time.

FIG. 4 is a schematic diagram showing an example of the colorimetric value trend. In the example shown in A of FIG. 4, the vertical axis represents the a * value and the horizontal axis represents the time. For example, by setting the data interval as the time required for the color measuring device to make one round, the longitudinal direction is used. The a * value on a straight line parallel to can be observed over time. In the example shown in B of FIG. 4, the vertical axis represents the a * value, and the horizontal axis represents the position of the color measurement point on the transport sheet in the width direction. This is useful for evaluating the presence or absence of color tone unevenness parallel to the width direction. By also displaying the management color tone value range 18 described later, it is possible to easily evaluate the presence or absence of deviation from the control color tone value range 18.

FIG. 5 is a schematic diagram showing an example of a coloring distribution. In the example shown in FIG. 5, the vertical axis represents the b * value and the horizontal axis represents the a * value, and the balance between the a * value and the b * value at each color measurement point can be evaluated. At this time, the observation period can be set by adjusting the time during which the evaluation result is displayed. The longer this time, the more color measurement points will be displayed, and the shorter this time, the fewer. This time can be adjusted as appropriate according to the purpose. By also displaying the management color tone value range 18 described later, it is possible to easily evaluate the presence or absence of deviation from the control color tone value range 18.

From the viewpoint of early grasping of abnormalities, the color measuring device of the present invention preferably includes a display means for displaying the thickness in combination with the color measurement value trend, the saturation distribution, and the color measurement / thickness measurement time. As an example, a method of managing the correlation between thickness and color tone value using a graph displaying at least one of L * value, a * value, and b * value on the horizontal axis and the thickness on the vertical axis, and the horizontal axis A method of managing the change in thickness over time by using a graph that displays the time and thickness on the vertical axis can be considered. By using such a mode, it is possible to determine at an early stage whether the deviation from the controlled color tone range is due to the thickness of the sheet, calculate the thickness adjustment amount for correcting the appropriate color tone value, and the like at an early stage.

The display means in the color measuring device of the present invention can display the color tone value data and the thickness measurement value data obtained by the calculation means at least one of the color measurement value trend, the saturation distribution, and the thickness measurement value. As long as it is installed in a mode, its type and installation position are not particularly limited. Further, as the display means, a known monitor or the like can be used in connection with the calculation means, or a monitor or the like integrated with the calculation means can be used.

In the color measuring device of the present invention, the color tone value is controlled on a straight line parallel to the longitudinal direction arbitrarily drawn on the transport sheet from the viewpoint of easily evaluating whether the color tone unevenness of the transport sheet is suppressed to a certain level. It is preferable to provide a verification means for verifying whether or not it is included in the value range. Here, the "straight line parallel to the longitudinal direction arbitrarily drawn on the transport sheet" means a straight line parallel to the longitudinal direction drawn on the transport sheet from an arbitrarily selected color measurement point, and the controlled color tone value range is. , Refers to the range of acceptable color tone values. The control color tone value range can be individually set for the required L * value, a * value, and b * value according to the purpose. By verifying whether or not the color tone value is included in the control color tone value range on the straight line, the presence or absence and degree of color tone unevenness in the direction parallel to the longitudinal direction can be easily evaluated.

The verification means in the color measuring device of the present invention is not particularly limited as long as it can set a controlled color tone value range and verify the relationship between the color tone value on a straight line parallel to the longitudinal direction and the controlled color tone value range, and is publicly known. Computers and software can be used in combination as appropriate. Further, the installation position is not particularly limited, and may be integrated with the calculation means. As a mode in which the verification means is integrated with the calculation means, for example, a state in which software for realizing the function of the verification means is also installed in a computer in which software for realizing the function of the calculation means is installed, that is, 1 An embodiment in which a computer is equipped with both a calculation means and a verification means can be mentioned.

Further, in the color measuring device of the present invention, from the viewpoint of early grasping of an abnormality, it is also preferable that the verification means has an alarm function for issuing an alarm when a color tone value outside the controlled color tone value range is observed. In order to make such an aspect, for example, a method of making a computer or software used as a verification means have such a function can be mentioned.

In the color measuring device of the present invention, the reciprocating light irradiating means, the light receiving means, and the driving portion and the traveling portion of the thickness measuring means are wear-resistant members and are in contact with each other during operation (hereinafter, the traveling portion side). The member of the above may be referred to as a member A and the member on the moving portion side may be referred to as a member B). It is preferable that the member has a dynamic friction coefficient μd satisfying 0.1 ≦ μd <0.3. Hereinafter, the coefficient of dynamic friction between the members may be simply referred to as the coefficient of dynamic friction. Here, the "driving unit" is a portion that comes into contact with the traveling unit when the light irradiating means, the light receiving means, and the thickness measuring means reciprocate, and is, for example, the wheel attached to the means or the means. Cable covers, bearings, etc. that move on the traveling portion that accompanies the reciprocating motion, which will be described later, fall under this category. The "traveling unit" is a portion on which the driving unit of each of the above means travels, and for example, a rail or the like corresponds to this. "Abrasion resistant member" means a member whose surface is less likely to be worn due to mechanical scratching or adhesion, for example, carbon steel, chrome steel, manganese steel, chrome molybdenum steel, chromoly steel, marten. Examples thereof include site-based stainless steel, precipitation-curing stainless steel, and austenite-based stainless steel. Further, the "member that comes into contact with each other during operation" refers to a drive unit and a traveling unit that come into contact with each other when the device operates.

In the color measuring device of the present invention, since the light irradiating means, the light receiving means, and the thickness measuring means reciprocate on the transport sheet, the driving part and the traveling part repeatedly contact and rub against each other to generate dust due to friction. Mitigation is required from the viewpoint of the quality of the finally obtained sheet. When the dynamic friction coefficient μd is 0.3 or less, the scattering of shavings due to the rubbing of the drive unit due to repeated reciprocating motion is suppressed, and the generation of scratches and adhered foreign substances due to their adhesion to the transport sheet is reduced. can.

On the other hand, when the dynamic friction coefficient μd is 0.1 or more, slippage of the light irradiating means, the light receiving means, and the thickness measuring means reciprocating on the traveling portion is suppressed, and acceleration / braking performance is maintained. The speed and mileage can be easily and correctly controlled. As a result, malfunctions due to slippage of the counter that measures the mileage are reduced, and the recognition accuracy of the measurement position is improved. Further, since the light irradiating means and the light receiving means operate individually with the transport sheet sandwiched between them, if the mileage of both cannot be controlled correctly, the positional relationship between them and the optical path are deviated, and the light irradiating means irradiates the light. Light may not be received correctly by the light receiving means, but if the dynamic friction coefficient μd is 0.1 or more, such a problem can be alleviated.

The coefficient of dynamic friction can be measured by the following procedure. First, a sample piece having the same material and surface condition as the member A and the member B and processed into a flat surface (referred to as a sample piece A and a sample piece B, respectively) is prepared. The weight of the sample piece B is W (g). The sample piece B is placed in contact with the sample piece A in a direction parallel to the ground, and a weight of 300 g is placed on the sample piece B. After that, a drawstring is attached to the sample piece B, and the pulling member B is slid in a direction parallel to the contact surface of the sample piece A and the sample piece B (direction parallel to the ground). At this time, the force F (g) required to keep the member B moving is measured, and the dynamic friction coefficient μd is obtained according to the following equation.
Equation: μd = F / (W + 300).

From the above viewpoint, it is preferable that the drive unit and the traveling unit are wear-resistant members and are composed of members having a dynamic friction coefficient of 0.1 or more and less than 0.3. A member having a dynamic friction coefficient of 0.1 or more and less than 0.3 is not particularly specified as long as the function of the device is not impaired, but an austenitic stainless steel (SUS304) material having an appropriately polished surface can be preferably used. ..

Hereinafter, the color measuring device of the present invention will be specifically described with reference to the color measuring device of the aspect A of FIG. 1 having a calculation means, a display means, and a verification means as an example. The color measuring device is not limited to the following aspects.

FIG. 6 is a schematic diagram showing a color measuring device of the aspect A of FIG. 1 including a calculation means, a display means, and a verification means. In the color measuring device 1 of the embodiment shown in FIG. 6, the light irradiating means 2 and the spectroscopic means 4 integrated with the light receiving means 3 are located on the upper surface side and the lower surface side thereof without contacting the transport sheet 5. Then, the spectroscopic means 4 including the light irradiating means 2 and the light receiving means 3 reciprocate along the rail 7 attached to the frame 6 in parallel with the width direction of the transport sheet 5. When the irradiation light 9 emitted by the light source 8 of the light irradiation means 2 reaches the transport sheet 5, transmitted light 10 and reflected light 11 are generated, and the transmitted light 10 is taken into the spectroscopic means 4 via the light receiving means 3. The transmitted light 10 captured in the spectroscopic means 4 is separated into a desired wavelength band by a movable slit 12 provided in the spectroscopic means 4 and taken into the main body 13 of the spectroscopic means, where the light is captured on the transport sheet 5. A spectroscopic spectrum at the light irradiation point is obtained.

Further, the light irradiation means 2 includes a radiation irradiation means A, and the radiation irradiation means A includes a radiation source. Further, the spectroscopic means 4 includes a radiation receiving means B, and the radiation receiving means B includes an ion chamber. By making such a mode, the color measuring means and the thickness measuring means are installed in close proximity, and at the same time, they reciprocate along the rail 7.

An imaging spectroscope can be preferably used as the spectroscopic means 4, and when the imaging spectroscope has, for example, a two-dimensional sensor including a monochrome CCD camera, the image is taken by the monochrome CCD camera in the two-dimensional sensor. The vertical direction of the CCD is the wavelength axis, and the horizontal direction is the position axis, which is converted into a spectroscopic spectrum corresponding to the color measurement position of the carrier sheet by the image pickup element of the CCD.

The radiation taken into the ion chamber by the radiation receiving means B is ionized by the electrodes provided in the ion chamber, and an ionizing current is generated according to the ionization energy. By detecting the ionizing current with an electrometer (not shown) and measuring the electromotive voltage, the radiation dose obtained by the radiation receiving means B is measured to calculate the attenuated radiation dose, and the thickness of the transport sheet 5 is determined. can get.

The spectroscopic means 4 is connected to a computer 19 including two CPUs via a cable. Hereinafter, each CPU in the computer 19 may be referred to as a first CPU 20 and a second CPU 21.

The first CPU 20 has a role of calculating a color tone value from the spectral spectrum obtained by the spectroscopic means 4, a role of calculating the thickness of the conveyed sheet 5 from the attenuated radiation amount, and data of the color tone value while the color measuring device is operating. Is transmitted to the second CPU 21, and the color tone value data is compared with a preset management color tone value range to make a pass / fail judgment. At this time, as one of the inspection conditions of the first CPU 20, the length of the transport sheet wound around one intermediate roll is set to the length in the longitudinal direction of the transport sheet to be inspected, so that the length of the transport sheet is set to one intermediate roll. The presence or absence of color tone unevenness and thickness unevenness can be easily evaluated. Further, the first CPU 20 may issue an alarm when the result of the pass / fail determination by comparing the color tone value data with the preset management color tone value range is "No".

Further, in addition to the spectroscopic means 4 and the second CPU 21, the input unit 22, the first display unit 23, and the first output unit 24 are also connected to the first CPU 20. The input unit 22 is a device that inputs inspection conditions such as control color tone values and gives instructions such as start and stop of color measurement. The first display unit 23 is a device for displaying color measurement results and inspection conditions in real time. The first output unit 24 is a device that prints out inspection conditions, inspection results, and the like on paper.

The second CPU 21 is connected to the first CPU 20 by a communication line 25, and is also connected to a second display unit 26 and a second output unit 27. The second CPU 21 has a function of editing the color measurement value obtained by the first CPU 20 into a color measurement value trend and a saturation distribution and a function of editing a thickness value into a thickness trend, and the conditions input by the first CPU 20. The obtained color measurement value and thickness value are immediately transmitted to the second CPU 21, edited in real time into the color measurement value trend, saturation distribution, and thickness value trend, and the color measurement value trend and saturation are displayed on the second display unit 26. Distribution data is displayed.

For the color measurement value trend, for example, it is preferable to display the time or the widthwise position of the color measurement point on the transport sheet as the horizontal axis, and at least one of the L * value, the a * value, and the b * value as the vertical axis. .. In addition, for example, the horizontal axis is time and the vertical axis is a * value, and the horizontal axis is time and the vertical axis is b * value. It is also possible to display a * value for a plurality of color measurement points and to combine these. By taking time on the horizontal axis in the color measurement value trend, the color tone at a certain color measurement point can be observed over time. On the other hand, by locating the transport sheet in the width direction on the horizontal axis, it is possible to observe the presence or absence of color unevenness in the direction parallel to the width direction of the transport sheet.

The saturation distribution is preferably represented as a scatter plot with the a * value obtained in an arbitrarily determined fixed period on the horizontal axis and the b * value on the vertical axis. This "arbitrarily determined fixed period" can be appropriately set according to the number of color measurement points to be displayed. The longer this period, the more historical data can be displayed.

Further, the second output unit 27 is a device that prints out the data of the colorimetric value trend and the saturation distribution on paper. By setting the second output unit 27 to print out data every time the color measurement of a certain unit winding length (time or number of times) is completed, it leads to efficiency improvement such as identification of defective products. be able to.

As described above, in the color measuring device of the aspect of FIG. 6, the first CPU 20 mainly plays the role of the calculation means and the verification means, and the second display unit 26 plays the role of the display means.

FIG. 7 is a flowchart showing a color measuring procedure in the color measuring device of FIG. First, the inspection conditions (object to be inspected, inspection date, inspection speed, color measurement interval, length in the longitudinal direction of the transport sheet to be inspected, etc.) are set on the first CPU 20 side. At this time, the length of the transport sheet to be inspected is one in the longitudinal direction so that the presence or absence of color tone unevenness in the intermediate roll (intermediate spool in FIG. 7) can be evaluated in one cycle of inspection. Set the length of the transport sheet to be wound on the intermediate roll.

Subsequently, the control color tone value range (control reference value in FIG. 7) on the first CPU 20 side is set. This setting may be set automatically by inputting color measurement conditions such as a color object to be measured in advance. Further, the control color tone value range may be the same range on the entire surface of the transport sheet, or may be set to a different range for each position in the width direction. After the setting of the management color tone value range is completed, the information is transmitted to the second CPU 21 side to set the display of the second CPU 21 and set whether to display the color measurement value trend or the saturation distribution (invention of the present invention). Both may be displayed as long as the effect is not impaired.)

In this way, after completing the preset settings of the first CPU 20 and the second CPU 21, after confirming the running of the conveyed film, the light irradiating means 2 and the spectroscopic means 4 integrated with the light receiving means 3 are operated to start color measurement. do. When the color measurement is started, the color tone value data at the color measurement point is accumulated in the first CPU 20 and then or simultaneously transferred to the second CPU 21. The first CPU 20 compares the accumulated color tone value data with the managed color tone value range, makes a pass / fail judgment, and displays the result on the first display unit 23. Further, the color tone value data transferred to the second CPU 21 is converted into a color measurement value trend and a saturation distribution, and these are displayed on the second display unit 26. The timing of data transfer from the first CPU 20 to the second CPU 21 is particularly preferably simultaneous with the accumulation from the viewpoint of real-time monitoring, but if it is difficult due to the specifications of the first CPU 20, a signal indicating intermediate roll rewinding, which will be described later, is transmitted. It can be the same timing as it is done.

At the timing when one cycle of this inspection is completed (the timing when the inspection of one intermediate roll is completed), the first CPU 20 transmits a signal (a signal indicating intermediate roll rewinding) to the second CPU 21, and the first output unit 24 and the first 2 The output unit 27 prints out the pass / fail determination result, the color measurement value trend, and the saturation distribution, respectively. From the results of the obtained print output, it is possible to evaluate the quality of the sheet wound on the obtained intermediate roll and determine whether or not the film formation can be continued.

The first CPU 20, the input unit 22, the first display unit 23, the first output unit 24, and the like can be configured by, for example, a personal computer "Optiplex" (registered trademark) series manufactured by Dell and its peripheral devices. From the viewpoint of recording inspection conditions, colorimetric value data, and the like for a long period of time, the first CPU 20 preferably includes a memory of about 2 GB and a built-in storage device (hard disk, etc.) of about 80 GB. The input unit 22 includes an inspection condition input device such as a keyboard and a switch for issuing a command to start or stop color measurement. When the start of color measurement is input by the switch, the light irradiation means 2 and the spectroscopic means 4 integrated with the light receiving means 3 move in parallel with the width direction of the transport sheet and perform color measurement according to preset conditions. , The pass / fail determination result accompanied by the position information is displayed on the first display unit 23. FIG. 8 shows an example of the pass / fail determination result displayed on the first display unit.

In the example of FIG. 8, the horizontal axis is 15 in the width direction and the vertical axis is 14 in the longitudinal direction to represent the seat surface. Here, the dotted line drawn in parallel with the longitudinal direction 14 corresponds to the width direction position of each color measurement point, and each point located above the dotted line represents a color tone abnormality point (reference numeral 28). It is also preferable that the color tone abnormality portion 28 displays which of L *, a *, and b * the abnormality has occurred so that it can be discriminated by the color and shape of the dots.

The second CPU 21 processes the color tone value data obtained by the first CPU 20, edits and displays the color measurement value trend and the saturation distribution on the second display unit 26 so as to arrange them on the same screen for each color measurement position. To bear. Further, the second CPU 21 has a function of superimposing a data unit (actual trend) on the colorimetric trend and the saturation distribution. Since the second CPU 21 requires a huge amount of data processing, it is preferable to provide a memory and a storage device equivalent to those of the first CPU 20. Further, as the second display unit 26 and the second output unit 27, the same ones as those of the first display unit 23 and the first output unit 24 can be used.

With the above configuration, it is possible to grasp the tendency of color unevenness of the conveyed sheet online, and it is possible to make a pass / fail judgment in the film forming process, manage the tendency, and quickly respond to an abnormality.

Although the specific embodiment of the color measuring device of the present invention has been described above, the present invention is not limited to the above embodiment, and various changes can be made within the range not impairing the effect of the present invention. For example, if a computer equipped with a CPU having sufficient processing capacity is used, the functions of the second CPU 21 described above can be integrated into the first CPU 20 to form a single system including a display unit and an output unit. .. Further, as for the display method of the color tone abnormality portion, the optimum display method can be appropriately adopted according to the purpose.

Hereinafter, the method for manufacturing the sheet of the present invention will be described. The sheet manufacturing method of the present invention is characterized in that the color tone of the conveyed sheet is controlled by using the color measuring device of the present invention. With such an aspect, it is possible to manage the tendency of the color tone of the sheet in-line, so that it is possible to make a pass / fail judgment, manage the tendency, and quickly respond to an abnormality in the color tone in the film forming process.

In the method for manufacturing a sheet of the present invention, the arrangement position and the number of the color measuring devices of the present invention are not particularly limited as long as the effect is not impaired. However, when stretching the sheet, it is preferable to set it downstream from the stretching step from the viewpoint of more reliably evaluating the quality of the final product.

Next, the method for producing a sheet of the present invention will be described below with reference to the production of a biaxially oriented polyethylene terephthalate (PET) film by a sequential biaxial stretching method. Not limited.

First, the resin pellets are supplied to the raw material input section of the extruder, and the resin is heated and melted. After that, the amount of resin extruded is made uniform by a gear pump or the like, the heated and melted resin is extruded, and foreign substances and gelled substances are removed through a filter or the like. At this time, the number of extruders may be one or a plurality, and when a plurality of extruders are used, the thermoplastic resin that has passed through the filter is sent to the laminating device. As the laminating device, a multi-manifold die, a feed block, a static mixer, or the like can be used, and these may be arbitrarily combined.

The resin melt thus obtained is discharged as a sheet-like melt from the mouthpiece, extruded onto a cooling body such as a casting drum, and cooled and solidified to obtain an unoriented sheet. As a specific method for obtaining a non-oriented sheet from a sheet-shaped melt, a wire-shaped, tape-shaped, needle-shaped or knife-shaped electrode is used to apply the sheet-shaped melt to a cooling body such as a casting drum by electrostatic force. A method of bringing them into close contact with each other and quenching and solidifying is preferable. Other methods include blowing air from a slit-shaped, spot-shaped or planar device to bring the sheet-shaped melt into close contact with a cooling body such as a casting drum to quench and solidify it, or cooling the sheet-shaped melt with a nip roll. A method of rapidly cooling and solidifying the product in close contact with the body is also preferable.

Next, the obtained non-aligned sheet is stretched in the longitudinal direction (longitudinal stretching) to obtain a uniaxially oriented sheet. The longitudinal stretching can be performed in one step using one or a plurality of stretching rolls having the same peripheral speed, or can be performed in multiple steps using a plurality of stretching rolls having different peripheral speeds. The magnification is preferably 2 to 7 times. In the longitudinal stretching, it is also possible to heat the non-oriented sheet with a preheating roll and then further heat the non-oriented sheet with an infrared heater or the like.

It is also possible to provide a step of applying a coating agent for forming a functional layer such as an easy-adhesion layer on both sides or one side of the obtained uniaxially oriented sheet after longitudinal stretching. The method for applying the coating agent is not particularly limited, and for example, a reverse coating method, a gravure coating method, a rod coating method, a bar coating method, a wire bar coating method, a die coating method, a spray coating method and the like can be used.

Then, the uniaxially oriented sheet obtained by longitudinal stretching is guided to a tenter device and stretched (transversely) in the width direction to obtain a biaxially oriented film. The tenter device grips both ends of the uniaxially oriented sheet in the width direction by a clip traveling inside the tenter device, and heats the uniaxially oriented sheet to the stretching temperature by traveling in the order of the preheating zone, the stretching zone, the heat fixing zone, and the cooling zone. Then, it is laterally stretched, and then heat-fixed and cooled. In this way, a biaxially oriented film can be obtained.

The temperature of the preheating zone and the stretching zone is preferably 80 to 160 ° C, more preferably 85 to 130 ° C, and 90 to 120, although it depends on the thickness of the finally obtained film, the stretching speed, the presence or absence of in-line coating, and the like. ° C is more preferred. By setting the temperature of the preheating zone and the stretching zone to 80 ° C. or higher, film breakage is reduced, and by setting the temperature to 160 ° C. or lower, a film having sufficient strength can be obtained. The magnification of lateral stretching depends on the thickness of the final film, the speed of stretching, the presence or absence of in-line coating, etc., but from the viewpoint of preventing uneven stretching and breakage of the film, it is 2.5 to 6.0 times. It is preferable, 3.0 to 5.5 times more preferably, and 3.5 to 5.0 times more preferably.

In the method for producing a sheet of the present invention, in order to reduce the occurrence of scratches and the like caused by friction of the film surface when winding as an intermediate roll described later after the lateral stretching step, knurls are used near both ends in the width direction. It may be embossed. It should be noted that such an embossed portion can be cut and removed in the process of making a final product, similarly to the edge portion having a large film thickness.

The biaxially oriented film thus obtained is cooled in the subsequent transfer process, once wound as an intermediate roll by a wide winder, and then cut into a required width and length by a slitter to form a final product. Become. By arranging the color measuring device of the present invention before winding it as an intermediate roll, for example, the color measuring error due to the color measuring point and the timing is reduced, and the color tone in the sheet width direction online is measured with higher accuracy. This also makes it possible to manage color tone trends more accurately in-line.

The film thus obtained has reduced color tone unevenness and can be used as various optical films. Specifically, it can be suitably used as a base film for a prism sheet, a base film for a hard coat, a base film for an antireflection (AR) film, a base film for light diffusion, a transparent conductive film and the like.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

[Resin used in film manufacturing]
The following resin A, resin B, and composition I were used in the production of the film.

(Resin A)
To a mixture of 100 parts by mass of dimethyl terephthalate and 60 parts by mass of ethylene glycol, 0.09 parts by mass of magnesium acetate and 0.03 parts by mass of antimony trioxide are added to the amount of dimethyl terephthalate, and the temperature is raised by heating by a conventional method. Then, a transesterification reaction was carried out. Then, 0.020 parts by mass of an 85% phosphoric acid aqueous solution was added to the transesterification reaction product with respect to the amount of dimethyl terephthalate, and then the mixture was transferred to a polycondensation reaction tank. Further, the reaction system was gradually depressurized while heating and raising the temperature, and a polycondensation reaction was carried out at 290 ° C. under a reduced pressure of 1 mmHg to obtain polyethylene terephthalate (PET) having an intrinsic viscosity (IV) of 0.61. This was designated as resin A.

(Resin B)
PET obtained by copolymerizing 21 mol% of spiroglycol (SPG) having an intrinsic viscosity (IV) of 0.60 and 24 mol% of cyclohexanedicarboxylic acid (CHDC) and resin A were mixed at a ratio of 4: 1 to obtain a copolymerized PET mixture. This was designated as resin B.

(Composition I)
(A) Acrylic / urethane copolymer resin aqueous dispersion: "Sannaron" WG-658 manufactured by Yamanan Synthetic Chemical Co., Ltd. (solid content concentration 30% by mass)
(B) Aqueous dispersion of compound containing isocyanate group and amino group: (solid content concentration 28% by mass)
(C) Epoxy compound (solid): "CR-5L" manufactured by DIC Corporation
(D) An aqueous dispersion of a composition composed of a compound having a polythiophene structure and a compound having an anionic structure: (solid content concentration 1.3% by mass)
(E) Aqueous dispersion of oxazoline compound: "Epocross" (registered trademark) WS-500 (solid content concentration 40% by mass) manufactured by Nippon Shokubai Co., Ltd.
(F) Aqueous dispersion of carbodiimide compound: "Carbodilite" (registered trademark) V-04 (solid content concentration 40% by mass) manufactured by Nisshinbo Holdings Inc.
(G) Silica particles: "Spherica" (registered trademark) slurry 140 (solid content concentration 40% by mass) manufactured by JGC Catalysts and Chemicals Co., Ltd.
(H) Acetylenediol-based surfactant: "Orfin" (registered trademark) EXP4051 (solid content concentration 50% by mass) manufactured by Nissin Chemical Co., Ltd.
(A) to (h) described above in terms of solid content mass ratio, (a) :( b): (c) :( d) :( e): (f) :( g) :( h) = 100 :. Composition I was prepared by mixing so as to be 100: 75: 25: 60: 60: 10: 15, and adjusting the concentration with pure water so that the solid content concentration was 3% by mass.

[Manufacturing of film]
A member having resin A and resin B put into separate twin-screw extruders with vents, resin A is melted at 280 ° C., resin B is melted at 270 ° C., and has 274 slits via a gear pump and a filter, respectively. Was merged with a 549-layer feed block having one separately. At this time, the two layers were alternately laminated so that the outermost layers on both sides of the thick film layer became the resin A, and the thicknesses of the adjacent layers made of the resin A and the layers made of the resin B were made substantially the same. .. Next, the laminated body of the molten resin thus obtained was guided to a T-die and molded into a sheet, and then brought into close contact with a casting drum maintained at a surface temperature of 25 ° C. by electrostatic application and rapidly cooled and solidified to form a non-oriented sheet. Got At this time, the thickness was finely adjusted by adjusting the gap of the base corresponding to the outlet portion of the T-die.

The obtained non-oriented sheet was heated in a roll group set at 75 ° C., then stretched 3.3 times in the vertical direction from both sides of the film while being rapidly heated by a radiation heater for a stretched section length of 100 mm, and then cooled once. A uniaxially oriented film was obtained. Next, both sides of the uniaxially oriented film were subjected to a corona discharge treatment in air, and the composition I of the easy-adhesion layer was applied to both sides with a # 4 wire bar.

Further, the uniaxially oriented film coated with the composition I was guided to a tenter device, preheated with hot air at 100 ° C., and stretched 3.5 times in the lateral direction at a temperature of 110 ° C. After that, heat treatment is performed with hot air at 240 ° C. in the same tenter device, a relaxation treatment of 7% in the width direction is performed at the same temperature, and the film is further cooled to room temperature to form a biaxially oriented film having a thickness of 70 μm and a width of 3,650 mm. Obtained. The biaxially oriented film thus obtained was wound with a winder to obtain a biaxially oriented film roll.

[Color measuring device]
(Color measuring device A)
The color measuring device of the embodiment shown in FIG. 6 was used. Hereinafter, the color measuring device will be specifically described. The color measuring device 1 has a light irradiation means 2 and a spectroscopic means 4, and a light receiving means 3 is attached to the spectroscopic means 4. At this time, the transport film 5 was adjusted to pass between the light irradiation means 2 and the spectroscopic means 4. The light irradiation means 2 and the spectroscopic means 4 are powered and reciprocate along a linear rail 7 attached to the frame 6. The transmitted light 10 reaches the inside of the spectroscopic means 4 via the light receiving means 3, is separated for each desired wavelength band by the movable slit 12 provided in the spectroscopic means 4, is taken into the main body 13 of the spectroscopic means, and has a spectroscopic spectrum. Is obtained.

Further, the light irradiation means 2 includes a radiation irradiation means A, and the radiation irradiation means A includes a krypton radiation source. Further, the spectroscopic means 4 includes a radiation receiving means B, and the radiation receiving means B includes an ion chamber. The radiation irradiating means A and the radiation receiving means B function as thickness measuring means. The radiation taken into the ion chamber via the radiation receiving means B is ionized by the electrodes included in the ion chamber, and an ionizing current is generated according to the ionization energy. By detecting the ionizing current with an electrometer (not shown) and measuring the electromotive voltage, the radiation dose incident on the radiation receiving means B is measured to obtain the attenuated radiation dose, and the conveyed sheet 5 is obtained from the attenuated radiation dose. The thickness of can be obtained.

As the light irradiation means 2, a light irradiation device equipped with a 100V, 180W halogen lamp (model LA-150UE SO24) and a light projecting lens (light receiving spot diameter φ18 mm (model ML-70)) was used. As the light receiving means 3, a light receiving lens (light receiving spot diameter φ15 mm (model ML-30)) was used. The spectroscope 4 includes an imaging spectroscope equipped with a two-dimensional sensor (imaging spectroscope: wavelength range 380 to 780 nm, wavelength resolution 2 nm, slit dimension width 30 μm, height 14.3 mm. Two-dimensional sensor: resolution 1,600. × 1,200, a sensor size of 11.84 × 8.88 mm, and a pixel size of 7.4 μm (Kodak model KAI-2020) were used.

The spectroscopic means 4 is connected to the first CPU 20 of the computer 19 having two CPUs (first CPU 20 and second CPU 21) via a cable, and the first CPU 20 is connected to the spectroscopic means 4 and the second CPU 21 as well as an input unit 22. , The first display unit 23, and the first output unit 24 are also connected. The second CPU 21 is connected to the first CPU 20 by a communication line 25, and is also connected to a second display unit 26 and a second output unit 27.

While the color measuring device is operating, the first CPU 20 has a role of calculating a color tone value from the spectral spectrum obtained by the spectroscopic means 4, a role of transmitting the color tone value data to the second CPU 21, and a role of transmitting the color tone value data to the second CPU 21 in advance. It plays a role of making a pass / fail judgment by comparing with the set management color tone value range. The input unit 22 is a device that inputs inspection conditions such as control color tone values and gives instructions such as start and stop of color measurement. The first display unit 23 is a device for displaying color measurement results and inspection conditions in real time. The first output unit 24 is a device that prints out inspection conditions, inspection results, and the like on paper. The second CPU 21 has a role of editing the color measurement value obtained by the first CPU 20 into a color measurement value trend and a saturation distribution and displaying the color measurement value on the second display unit 26 in real time. The second output unit 27 is a device that prints out the data of the colorimetric value trend and the saturation distribution on paper.

The computer 19, the input unit 22, the first display unit 23, the first output unit 24, the second display unit 26, and the second output unit 27 are the personal computer "Optiplex" (registered trademark) series manufactured by Dell. And its peripherals.

(Color measuring device B)
The multipoint simultaneous color measuring device of the embodiment shown in FIG. 9 was used. Hereinafter, the color measuring device will be specifically described. In the color measuring device 1, 19 light projecting portions 31 are connected to two light sources 29 having a built-in shutter attached to the upper side of the frame 6 via an optical fiber 30 branched into 19 (that is, a built-in shutter). The light source 29, the optical fiber 30 connected to the light source 29, and the light projecting unit 31 correspond to the light irradiation means 2, and there are 38 light projecting units 31 in total). Further, 38 light receiving portions 32 (corresponding to the light receiving means 3) are connected to the spectroscopic means 4 attached to the lower side of the frame 6 via the optical fiber 30 branched into 38 pieces. The light emitted by the light source 29 with a built-in shutter reaches the carrier film 5 as irradiation light 9 from the light projecting unit 31 via the optical fiber 30, and the transmitted light 10 transmitted through the light is transmitted from the light receiving unit 32 to the spectroscopic means 4 through the optical fiber 30. It is taken in and the spectroscopic spectrum can be obtained by the spectroscopic means 4.

Both the light projecting unit 31 and the light receiving unit 32 were arranged linearly at intervals of 100 mm. As the light source 29 with a built-in shutter, a halogen lamp (model MHAA-100W-650-SO) with a 12V, 100W dichroic mirror was used. As the optical fiber 30, a plastic one was used on the light emitting portion 31 side and a quartz one was used on the light receiving portion 32 side (both have a fiber length of 4 m). As the light projecting unit 31, a lens having a light receiving spot diameter of φ18 mm (model ML-70) was used. As the light receiving unit 32, a light receiving spot diameter of φ15 mm (model ML-30) was used. The devices connected to the spectroscopic means 4, the computer 19, and the computer 19 and their roles were the same as those in the first embodiment.

Further, when the color measuring device B is used, it is separately provided with a radiation irradiating means having a krypton radiation source and a radiation receiving means having an ion chamber, and reciprocates by power along a linear rail attached to the frame. A thickness measuring means (not shown) was installed.

(Dynamic friction coefficient)
First, a sample piece having the same material and surface condition as the member A and the member B and processed into a flat surface (referred to as a sample piece A and a sample piece B, respectively) was prepared. The weight of the sample piece B was W (g). The sample piece B was placed in contact with the sample piece A in a direction parallel to the ground, and a weight of 300 g was placed on the sample piece B. Then, a drawstring was attached to the sample piece B, and the pulling member B was slid in a direction parallel to the contact surface of the sample piece A and the sample piece B (a direction parallel to the ground). At this time, the force F (g) required to keep the member B moving was measured, and the dynamic friction coefficient μd was obtained according to the following equation.
Equation: μd = F / (W + 300).

[evaluation]
(Correlation between thickness value and color tone)
During the 50 reciprocating measurements described in Examples 1 and 2 and Comparative Example 1 described later, the film thickness was intermittently varied within ± 3 μm in the width direction and the longitudinal direction, respectively. The thickness was adjusted by adjusting the gap between the T-dies. Using all the measured values at this time, the absolute values | r | of the following three correlation coefficients were calculated. Based on the absolute value of the obtained correlation coefficient, it was evaluated according to the following evaluation criteria.
<Correlation coefficient>
・ Thickness value and L *
・ Thickness value and a *
・ Thickness value and b *
<Evaluation criteria>
◯: Of the three, two or more had a correlation coefficient | r | ≧ 0.8.
X: Of the three, two or more had a correlation coefficient | r | <0.8.
(Shavings from reciprocating motion)
In addition to the 50 round trip measurements for evaluating the correlation between the thickness value and the color tone, 1000 round trips were further measured. The number of shavings adhering to the sheet conveyed during that period was counted using an in-line defect inspection machine Iris-M (manufactured by Ayaha Engineering Co., Ltd.). The number of adhered foreign substances contained in the total length of the film conveyed during 1000 round trips was evaluated according to the following evaluation criteria.
<Evaluation criteria>
◯: The number of adhered foreign substances was less than 10.
X: There were 10 or more adhered foreign substances.
(Comprehensive evaluation)
The comprehensive evaluation was made as follows based on the evaluation results of (correlation between thickness value and color tone) and (shavings due to reciprocating motion), and ○ and Δ were evaluated as acceptable, and × was regarded as unacceptable.
○: (correlation between thickness value and color tone) and (shavings due to reciprocating motion) were both ○ △: (correlation between thickness value and color tone) was ○, and (shavings due to reciprocating motion) ×. X: (correlation between thickness value and color tone) was x.

(Example 1)
With respect to the film obtained by the method described in the section of [Manufacturing of film], immediately before the step of winding the obtained film with a winder, the color is measured using (color measuring device A) described in [color measuring device]. , And thickness measurements were performed. At that time, the light receiving means 3 attached to the light irradiating means 2, the spectroscopic means 4, and the spectroscopic means 4 (hereinafter, these may be collectively referred to as a set of color measuring devices) are parallel and linear with the conveying film 5. It was set to reciprocate at a distance of 4,000 mm. The surface-polished SUS material (between members) is used for the members (members A and B, the member on the traveling portion side is referred to as member A, and the member on the moving portion side is referred to as member B) in which contact / rubbing occurs due to the reciprocating motion. The dynamic friction coefficient of μd = 0.25) was used. The first color measurement is performed at the timing when the set of color measuring devices advances 200 mm from the start point (one end) of the reciprocating motion to acquire the data of L * value, a * value, and b * value, and then the reciprocating motion. The same color measurement was repeated every 100 mm until the distance from the start point of was 3,800 mm (the number of color measurements during this period was 37). Further, after the set of color measuring instruments reached the end point of the reciprocating motion (the end opposite to the starting point), it was driven in the opposite direction to perform the same color measurement. By repeating this measurement over 50 round trips in the same color measurement and thickness measurement, a total of 3,700 color measurements were performed on the conveyed film 5. When the obtained values (L * value, a * value, and b * value) and the thickness value were used for evaluation according to the item of [Evaluation], the correlation between the thickness value and the color tone, and the evaluation of the shavings by the reciprocating motion. Both became ○, so the overall evaluation was also ○. The shavings due to the reciprocating motion were evaluated after further measurement over 1,000 reciprocating motions.

(Example 2)
Measurement and evaluation were carried out in the same manner as in Example 1 except that an aluminum material (dynamic friction coefficient μd between members μd = 0.60) was used for the member that causes contact and rubbing due to reciprocating motion. As a result, the correlation between the thickness value and the color tone was performed. Was ○, and the evaluation of shavings due to reciprocating motion was ×, so the overall evaluation was △. The shavings due to the reciprocating motion were evaluated after further measurement over 1,000 reciprocating motions.

(Example 3)
When the same procedure as in Example 1 is carried out except that the mirror-polished SUS (dynamic friction coefficient μd between members μd = 0.09) is used for the member in which contact / rubbing occurs due to the reciprocating motion, the correlation between the thickness value and the color tone and the reciprocating motion are performed. The evaluation of the shavings by is both ○, but when the actual measurement position gradually deviates from the target measurement position and the reciprocating measurement is repeated continuously even after exceeding 50 reciprocating motions, the light irradiation means is finally used. If the positional relationship of the light receiving means shifts, it becomes impossible to measure the color tone correctly. Therefore, it is superior to Comparative Example 1 but inferior to Example 1.

(Comparative Example 1)
The color was measured using (color measuring device B) described in [Color measuring device], and the thickness was measured using a separately installed thickness measuring means. At that time, the thickness measuring means was measured by the same reciprocating motion as described in Example 1. Further, while the thickness measuring means measures the thickness 37 times on the outward path, the color measuring device B simultaneously measures 37 points in the width direction once to acquire data. By repeating this measurement with the thickness measuring means for 50 round trips in the same thickness measurement and color measurement, a total of 3,700 times of color measurement was performed on the conveyed film 5. When the obtained values (L * value, a * value, and b * value) and the thickness value were used for evaluation according to the item of [Evaluation], the correlation between the thickness value and the color tone was ×, so a comprehensive evaluation was made. Also became x.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to manage the tendency of the color tone of a sheet in-line, and to provide a color measuring device having excellent accuracy. By using the color measuring device of the present invention for manufacturing a sheet used in applications where the required level of color tone uniformity is high (for example, optical applications, decorative applications, wavelength selection applications, etc.), quality improvement and early defective products can be achieved. Elimination is possible.

1 Color measuring device 2 Light irradiation means 3 Light receiving means 4 Spectroscopic means 5 Conveying sheet 6 Frame 7 Rail 8 Light source 9 Irradiation light 10 Transmitted light 11 Reflected light 12 Slit 13 Spectral means main body 14 Longitudinal direction 15 Width direction 16 Color measuring point 17 Length in the width direction between color measurement points 18 Controlled color adjustment range 19 Electronic computer 20 1st CPU
21 2nd CPU
22 Input unit 23 1st display unit 24 1st output unit 25 Communication line 26 2nd display unit 27 2nd output unit 28 Color tone abnormality location 29 Shutter built-in light source 30 Optical fiber 31 Light emitting unit 32 Light receiving unit A Radiation irradiation means B Radiation receiving means

Claims (12)

Light irradiation means that irradiates the transport sheet with light,
A light receiving means that receives at least one of the transmitted light transmitted through the transport sheet and the reflected light reflected by the transport sheet.
And a spectroscopic means for detecting a color by acquiring a spectroscopic spectrum of light received by the light receiving means.
The light irradiation means and the light receiving means are provided with a thickness measuring means.
A color measuring device, wherein the light irradiating means, the light receiving means, and the thickness measuring means reciprocate in parallel with the width direction of the transport sheet. The color measuring device according to claim 1, wherein the color is measured at regular intervals in the width direction of the transport sheet. The color measurement according to claim 1 or 2, wherein the light irradiation means, the light receiving means, and the thickness measuring means perform zero point correction at a timing outside the widthwise end portion of the transport sheet. Device. Any of claims 1 to 3, wherein at least one of the range within 30 cm from the center of the light source of the light irradiation means and the range within 30 cm from the center of the light irradiation point of the light receiving means is dark. Color measuring device described in Crab. The color measuring device according to any one of claims 1 to 4, further comprising a calculation means for obtaining a color tone value from the spectral spectrum. The color measuring device according to claim 5, further comprising a display means for displaying the color tone value in real time at at least one of the color measurement value trend and the saturation distribution. The fifth or sixth aspect of the present invention, wherein the transport sheet is provided with a verification means for verifying whether or not the color tone value is included in the control color tone value range on a straight line parallel to the longitudinal direction arbitrarily drawn. Color measuring device. The color measuring device according to claim 7, wherein the verification means includes an alarm function for issuing an alarm when a color tone value outside the controlled color tone value range is observed. 6. The thickness measuring means is characterized in that the thickness value at a position where the distance from the color measuring point is 0 mm or more and 500 mm or less is measured, and the thickness value trend is displayed on the display means in real time. The color measuring device according to any one of 8 to 8. The color measuring device according to claim 9, wherein the correlation between the color measuring trend and the thickness value trend is obtained. The reciprocating light irradiating means, the light receiving means, and the driving part and the traveling part of the thickness measuring means are wear-resistant members, and the dynamic friction coefficient μd between the members in contact during operation is 0.1 ≦ μd <0. The color measuring device according to any one of claims 1 to 10, wherein the member is a member satisfying 3. A method for manufacturing a sheet, which comprises using the color measuring device according to any one of claims 1 to 11 to control the color tone and the thickness of the conveyed sheet.

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