JP2016148779A - Method of measuring optical film, optical film measuring device, and method of manufacturing optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to accurately measure the dimensions of components even when a PET film is arranged.SOLUTION: There is provided a method of measuring an optical film 1 in which a phase difference layer 4 including first and second areas having slow axis directions different from each other is provided on a laminate including a transparent film material 2 or a PET film, the method comprising the steps of: making linearly polarized light and monochromatic measurement light incident obliquely on the optical film 1 and making reflected light incident through a linear polarization plate 15 to photograph the optical film 1 to acquire results of imaging of the first and second areas having contrasts different from each other; and performing image processing on the imaging results to measure the dimensions of the first and second areas.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical film such as a pattern retardation film according to a passive three-dimensional image display.

  In recent years, an image display device that displays a three-dimensional image by a passive method has been provided. Here, FIG. 4 is a schematic view showing a passive type image display device using a liquid crystal display panel. The passive-type image display device sequentially assigns pixels of the liquid crystal display panel that are continuous in the vertical direction or the horizontal direction (vertical direction in the example of FIG. 4) for the right eye and the left eye, respectively. Driving with the image data for the left eye, thereby displaying the image for the right eye and the image for the left eye simultaneously. In addition, a pattern retardation film is arranged on the panel surface (viewer side) of the liquid crystal display panel so that the light emitted from the right-eye pixel and the left-eye pixel is linearly polarized light having different directions for the right-eye and left-eye. Convert to As a result, in the passive method, glasses equipped with corresponding polarizing filters are worn, and a right-eye image and a left-eye image are selectively provided to the viewer's right and left eyes, respectively, and a three-dimensional image is displayed. To do.

  Therefore, in the pattern retardation film, two types of band-like regions in which the slow axis direction (direction in which the refractive index is maximized) are orthogonal to each other are sequentially formed corresponding to the setting of the pixels in the liquid crystal display panel. Here, as the slow axis direction of the adjacent belt-like regions, a combination of +45 degrees and −45 degrees, or 0 degrees and +90 degrees with respect to the horizontal direction is usually employed. In the example of FIG. 4, the long side direction of the screen is shown as the horizontal direction in accordance with the name in the normal image display device.

  Conventionally, a patterned retardation film is produced by sequentially producing an alignment film and a retardation layer while transporting a substrate made of a film material such as TAC (triacetylcellulose), which is a transparent film material with small optical anisotropy. Is done. In addition, an adhesive layer, a separator film, and the like for use in attachment to the image display panel are further provided.

  When the dimensional accuracy of the pattern phase difference film is lowered, the relative position accuracy with respect to the corresponding pixel is lowered, so that crosstalk occurs and the image quality is remarkably deteriorated. Here, crosstalk is a phenomenon in which light emitted from the image display panel that should be supplied to the right and left eyes originally leaks to the left and right eyes. For this reason, conventionally, in the manufacturing process of the pattern retardation film, in the state where the pattern retardation film is arranged between a pair of linear polarizing plates by crossed Nicol arrangement or parallel Nicol arrangement at the stage before providing the adhesive and separator film, The dimension of the belt-like region formed on the pattern retardation film was measured by transmitted light, and the measurement result was used for product management. In this measurement method, a quarter-wave plate is disposed between the pattern retardation film and the outgoing light side linear polarizing plate as necessary.

  With respect to the pattern retardation film according to such a passive method, Patent Documents 1 and 2 propose a method of measuring the dimensions of each part with transmitted light.

  By the way, in a pattern phase difference film, it is desired to measure the dimensions of each part in a state where an adhesive layer and a separator film which are final forms are arranged. However, the PET (polyester) film normally used for the separator film has a large retardation value, so that in the state where the separator film is arranged, the measurement method using transmitted light, which is a conventional method, can identify adjacent band-like regions. After all, it was difficult to measure the dimensions of each part.

JP 2013-15563 A JP 2013-15564 A

  The present invention has been proposed in view of such circumstances, and an object of the present invention is to enable accurate measurement of the dimensions of each part even when a PET film or the like is placed.

  This inventor repeated earnest examination in order to solve the subject mentioned above. As a result, the present invention has been completed with the idea that the dimensions of each part are measured by reflected light by oblique incidence.

  Specifically, the present invention provides the following.

(1) In the measurement method of the optical film in which the retardation layer having the first and second regions having different slow axis directions is provided on the transparent film material or the laminate including the PET film,
A linearly polarized light and monochromatic light are incident obliquely on the optical film, and reflected light is incident through the linear polarizing plate to image the optical film, thereby providing contrast in the first and second regions. Get different imaging results,
A method for measuring an optical film, which performs image processing on the imaging result and measures dimensions according to the first and second regions.

  According to (1), the first and second regions are sufficient even when a member having a large retardation value is provided on the optical film by acquiring an imaging result using reflected light by oblique incidence. The imaging result can be acquired while ensuring the contrast ratio, and thereby the dimensions of each part can be measured with high accuracy even when a PET film or the like is placed.

(2) In (1),
An optical film measuring method in which a quarter-wave plate is provided on the optical film side of the linearly polarizing plate.

  According to (2), it is possible to obtain an imaging result with a much higher contrast ratio by adjusting the quarter-wave plate.

(3) In (1) or (2),
A method for measuring an optical film, wherein the optical film is a pattern retardation film.

  According to (3), it can apply to a pattern phase difference film, and can measure the dimension of each part with high precision also in the state where PET film etc. are arranged.

(4) About the optical film in which the retardation film provided with the 1st and 2nd area | region where a slow axis direction differs is provided in the laminated body containing a transparent film material or a PET film, said 1st and 2nd In the optical film measuring device for measuring the dimensions related to the area,
Linearly polarized light, optical system on the light source side that obliquely enters measurement light by monochromatic light on the optical film,
An imaging-side optical system that acquires an imaging result from reflected light of the measurement light,
The optical system on the light source side
A light source that emits monochromatic measuring light;
A linear polarizing plate that converts measurement light emitted from the light source into measurement light by linear polarization;
The imaging side optical system is:
A quarter-wave plate that transmits the reflected light from the optical film;
A linearly polarizing plate that transmits the transmitted light of the quarter-wave plate;
An imaging device that receives the light transmitted through the linearly polarizing plate and outputs an imaging result; and
The optical film measuring device comprises:
An optical film measuring device that acquires a measurement result of the dimension by image processing of an imaging result obtained by the imaging device.

  According to (4), the first and second regions are sufficient even when a member having a large retardation value is provided on the optical film by acquiring an imaging result using reflected light by oblique incidence. The imaging result can be acquired while ensuring the contrast ratio, and thereby the dimensions of each part can be measured with high accuracy even when a PET film or the like is placed.

(5) In the method for producing an optical film in which a transparent film material or a laminate including a PET film is provided with a retardation layer having first and second regions having different slow axis directions,
Linearly polarized light, monochromatic light measurement light is obliquely incident on the optical film, and reflected light is imaged through a linear polarizing plate to obtain imaging results having different contrasts in the first and second regions,
Processing the imaging result to measure a dimension related to repetition of the first and second regions;
The manufacturing method of the optical film which manages the manufacturing process of the said optical film with a measurement result.

  According to (5), the first and second regions are sufficient even when a member having a large retardation value is provided on the optical film by acquiring the imaging result using reflected light by oblique incidence. The imaging result can be acquired while ensuring the contrast ratio, and thereby the dimensions of each part can be measured with high accuracy even when a PET film or the like is placed.

  According to the present invention, the dimensions of each part can be accurately measured even when a PET film or the like is placed.

It is a figure which shows the pattern phase difference film which concerns on 1st Embodiment of this invention. It is a figure which shows the manufacturing process of the pattern phase difference film of FIG. It is a figure where it uses for description of a measurement process. It is a figure where it uses for description of a pattern phase difference film.

[First Embodiment]
(Image display device)
FIG. 1 is a view showing a pattern retardation film according to the first embodiment of the present invention. In the image display device according to this embodiment, the pixels of the liquid crystal display panel that are continuous in the vertical direction (the left-right direction in FIG. 1) sequentially display the right-eye pixel for displaying the right-eye image and the left-eye image. They are distributed to the left-eye pixels to be displayed, and are driven by right-eye and left-eye image data, respectively. As a result, the image display device alternately divides the display screen into a band-like region for displaying an image for the right eye and a band-like region for displaying an image for the left eye. Display at the same time. In this image display device, the pattern phase difference film 1 shown in FIG. 1 is disposed on the panel surface of the liquid crystal display panel, and the pattern phase difference film 1 corresponds to light emitted from pixels for the right eye and the left eye, respectively. To give the phase difference. Thereby, this image display apparatus displays a desired three-dimensional image by a passive method.

[Pattern retardation film]
In the pattern retardation film 1, for example, an orientation layer 3, a retardation layer 4, an adhesive layer 5, and a separator film 6 are sequentially provided on one side of a base material 2 made of a transparent film material of triacetyl cellulose. The pattern phase difference film 1 exposes the adhesive layer 5 by peeling the separator film 6, and is disposed on the panel surface of the image display panel by the adhesive layer 5.

  In the pattern retardation film 1, the retardation layer 4 is formed of a liquid crystal material, and the alignment of the liquid crystal material is patterned by the alignment regulating force of the alignment layer 3. The orientation of the liquid crystal molecules is indicated by a long and narrow ellipse in FIG. By this patterning, the pattern phase difference film 1 is formed in a band shape alternately with the right-eye area A and the left-eye area B sequentially with a certain width corresponding to the pixel assignment in the liquid crystal display panel. A phase difference corresponding to each of the light emitted from the right-eye and left-eye pixels is given.

  In the pattern retardation film 1, after the photo-alignment material layer made of the photo-alignment material is produced, the alignment layer 3 is produced by irradiating the photo-alignment material layer with ultraviolet rays by linearly polarized light by a so-called photo-alignment technique. Here, the ultraviolet rays applied to the photo-alignment material layer are set such that the direction of polarization differs between the right-eye region A and the left-eye region B by 90 degrees. The retardation layer 4 is produced by solidifying (curing) the liquid crystal material in an aligned state by the alignment regulating force of the alignment layer 3, whereby the pattern retardation film 1 includes the right eye region A and the left eye region. B gives a phase difference corresponding to the transmitted light.

〔Manufacturing process〕
FIG. 2 is a flowchart showing manufacturing steps of the pattern retardation film 1. In the manufacturing process of the pattern retardation film 1, the base material 2 is provided by a long transparent film material wound up on a roll, and the alignment layer material layer is sequentially produced while the base material 2 is fed out from the roll and conveyed ( Step SP1-SP2). Here, although various manufacturing methods can be applied to the alignment layer material layer, in this embodiment, a coating liquid in which a photo-alignment material is dispersed in a solvent such as benzene is applied by a die and then dried. Produced. As the photo-alignment material, various materials to which a photo-alignment technique can be applied can be applied.

  Subsequently, in this manufacturing process, an alignment layer is formed by irradiating ultraviolet rays in the exposure process (step SP3). Subsequently, in this manufacturing process, in the retardation layer manufacturing process (step SP4), the coating liquid for the retardation layer is applied with a die or the like, and then dried. Subsequently, the coating layer of the retardation layer is irradiated with ultraviolet rays, whereby the liquid crystal material is solidified (cured) in an aligned state by the alignment regulating force of the alignment layer 3, and the retardation layer 4 is produced. Then, this manufacturing process produces the adhesion layer 5 by coating the coating liquid of the adhesion layer 5 in adhesion layer preparation process SP5. In the subsequent separator film arrangement step SP6, the separator film 6 is arranged. Thereby, this manufacturing process produces a pattern phase difference film by a long film shape.

  In this manufacturing process, in the subsequent measurement process SP7, the dimension is measured while the pattern retardation film having the long film shape thus produced is conveyed in-line. Here, this dimension is measured by measuring a total pitch defined by the width of a predetermined number of belt-like regions corresponding to the upper and lower ends of the screen. In this manufacturing process, the total pitch is sequentially measured in the longitudinal direction of the pattern phase difference film by this long film shape by measuring at a constant time interval while conveying the pattern phase difference film.

  In the subsequent cutting process SP8, this manufacturing process cuts the pattern retardation film having a long film shape into a size to be attached to the panel surface of the corresponding image display panel. At the time of this cutting, this manufacturing process selects the part where the total pitch passes the product standard based on the measurement result measured in step SP7, and cuts the pattern retardation film, thereby controlling the measurement result as a process control. To use. When using the measurement results for process management, for example, the center of the total pitch distribution can be determined by varying the tension during substrate transport, varying the drying temperature of the coating liquid for the alignment layer and / or retardation layer, etc. It can be widely applied to various process management such as variable.

[Measurement process]
FIG. 3 is a diagram for explaining the measurement process. In this measurement step, the total pitch of the pattern retardation film 1 is measured by the measurement device 11. Here, in the manufacturing process, the pattern retardation film having a long film shape is guided by the guide roller 12 disposed on the lower side and conveyed in the horizontal direction with the base material 2 positioned on the upper side. Here, the pattern retardation film 1 conveyed in this way vibrates up and down during the conveyance process, and such vibration makes measurement of dimensions difficult. Therefore, this manufacturing process optically measures the dimension of the pattern retardation film from above the pattern retardation film 1 directly above the guide roller 12 at the position of the guide roller 12 where the vertical vibration is suppressed. Therefore, the total pitch can be measured reliably by effectively avoiding deterioration of measurement accuracy.

  The dimension may be measured by pressing the pattern phase difference film in the conveyance process from above with a guide roller and optically measuring the dimension from below, and conveying the pattern phase difference film in the vertical direction. In this way, the dimensions may be measured optically from the side opposite to the side in the pressing direction while being pressed by the guide roller from the side.

  The measurement device 11 emits measurement light, which is measurement light, from the light source 10, converts the measurement light into linearly polarized light by the linearly polarizing plate 13, and obliquely enters the pattern retardation film 1 from the substrate 2 side. Here, the measurement light is monochromatic light, and thus, for example, a laser light source is applied to the light source 10. The measuring device 11 is configured so that the direction of the polarization plane of the measurement light by the linearly polarized light according to this oblique incidence is 45 degrees with respect to the slow axis direction of the band-like regions A and B in the pattern retardation film 1 ( The direction of the linearly polarizing plate 13 is set) (the extending direction of the strip regions A and B or the direction orthogonal to the extending direction). Further, the incident direction of the measurement light is set so as to be in a direction crossing the pattern retardation film 1 (repeating direction of the band-like region) when viewed from above the pattern retardation film 1.

  As described above, the measurement light incident obliquely by the linearly polarized light that forms an angle of 45 degrees with respect to the slow axis direction of the band-like regions A and B is the surface of the pattern retardation film 1 and each constituent member constituting the pattern retardation film. The light is reflected and emitted from the boundary surface, the surface of the guide roller 12, and the like. Focusing on the reflection on the side surface of the adhesive layer 5 of the retardation layer 4 among the reflected light on each of these boundary surfaces and the like, when the measurement light is perpendicularly incident on the surface of the pattern retardation film 1 (incident angle θ1 = 0) In this case, the measurement light is converted into circularly polarized light having different directions by adding a phase difference of +1/4 wavelength and -1/4 wavelength in the band-like regions A and B in the retardation layer 4, respectively. The light is reflected at the adhesive layer 5 side interface, and the direction according to the circularly polarized light is reversed during the reflection. Further, the reflected light by the inverted circularly polarized light is emitted after being converted into linearly polarized light having the same plane of polarization in the band-like regions A and B due to the phase difference by the phase difference layer 4. As a result, the regions A and B cannot be identified depending on the reflected light of the incident light that is vertically incident in this way, and the total pitch cannot be measured.

  However, when the measurement light is obliquely incident as in this embodiment, the incident light is given a phase difference different from the quarter wavelength in the phase difference layer 4, so that the band-shaped regions A and B The elliptical polarized light whose major axis direction is symmetric with respect to the extending direction reaches the interface on the adhesive layer 5 side, and here, the rotational direction related to the elliptically polarized light is reversed. Further, the reflected light by the elliptically polarized light thus inverted is given a phase difference different from the quarter wavelength in the phase difference layer 4, and as a result, the reflected light has different major axis directions in the belt-like regions A and B. The light is emitted by elliptically polarized light. As a result, according to the obliquely incident light as described above, it is possible to identify the strip regions A and B in the reflected light.

  In addition, the reflection light reflected on the side surface of the pressure-sensitive adhesive layer 5 of the retardation layer 4 is not transmitted through the separator film 6, so that the retardation in the separator film 6 is measured as in the case of measuring the dimensions with the transmitted light. It can be used for measurement of dimensions without being affected by the value.

  Therefore, in this measuring apparatus 11, for the outgoing light that is emitted after being regularly reflected by the pattern retardation film 1 (outgoing each θ2 = reflected light at the incident angle θ1), a quarter wavelength is provided on the optical path of the reflected light. The plate 14, the linearly polarizing plate 15, and the imaging device 16 are sequentially arranged. Here, the directions of the quarter-wave plate 14 and the linearly polarizing plate 15 are adjusted so that the contrast ratio can be secured most in the strip regions A and B. In the adjustment of the contrast ratio, the quarter-wave plate 14 may be omitted if a sufficient contrast ratio can be secured in practice. As a result, in the measurement apparatus 11, the imaging device 16 captures the band-like areas A and B with the highlight and the low light, respectively, or conversely, the band-like areas A and B with the low light and the highlight, respectively. The obtained imaging result can be obtained, and the areas A and B can be identified by the contrast difference in the imaging result, and the total pitch can be measured.

  That is, the measuring device 11 captures the imaging result of the imaging device 16 at the computer 17 at time intervals used for measurement. The computer 17 measures the total pitch by image processing of the captured imaging result. More specifically, for example, the computer 17 extracts the contour from the imaging result to detect the boundary between the strip regions A and B, and measures the boundary by the number corresponding to the total pitch in the direction crossing the strip regions A and B. The total pitch on the imaging result is measured, and the total pitch is calculated by multiplying the measurement result on the imaging result by the magnification according to the imaging result.

  By the way, the obliquely incident measurement light includes the interface between the substrate 2 and the alignment layer 3 of the pattern retardation film 1, the interface between the alignment layer 3 and the retardation layer 4, the interface between the adhesive layer 5 and the separator film 6, and the separator film. And the guide roller 12 are also reflected, and the reflected light also enters the imaging device 16. The reflected light from such an interface will reduce the contrast ratio of the band-like regions A and B, which will reduce the dimensional measurement accuracy of the pattern retardation film 1, and in a severe case, the measurement itself becomes difficult. .

  Here, when the incident angle θ1 of the measurement light is small, the contrast ratio of the strip regions A and B in the imaging result is remarkably large because the amount of reflected light reflected at the interface of the separator film 6 (the surface of the guide roller) is large. It has been found that the contrast ratio of the band-like regions A and B in the imaging result increases as the incident angle θ1 increases.

  However, as the incident angle θ1 of the measurement light increases, the contour becomes blurred in the imaging result acquired by the imaging device 16, and it becomes difficult to extract the contour in the processing of the imaging result. According to various investigation results, it is possible to set the incident angle θ1 to 30 degrees or more and 50 degrees or less, more preferably to set the incident angle θ1 to 30 degrees or more and 40 degrees or less, and to measure the dimensions reliably. it can.

  Thereby, in this embodiment, the light source 10 and the linearly polarizing plate 13 constitute an optical system on the light source side that obliquely enters measurement light of linearly polarized light and monochromatic light on the pattern retardation film 1 that is an optical film to be measured. The quarter-wave plate 14, the linearly polarizing plate 15, and the imaging device 16 constitute an imaging-side optical system that acquires an imaging result from reflected light of measurement light.

[Other Embodiments]
As mentioned above, although the specific structure suitable for implementation of this invention was explained in full detail, this invention can change the structure of the above-mentioned embodiment variously in the range which does not deviate from the meaning of this invention.

  That is, in the above-described embodiment, the case where the alignment layer is formed using the photo-alignment layer has been described. However, the present invention is not limited thereto, and when the alignment layer is formed by rubbing, a fine line-shaped uneven shape is formed. The method can be widely applied to the case where an alignment layer is produced by transfer. In addition, a retardation layer may be prepared from a photoalignable liquid crystal polymer having a photoalignment function, and the alignment layer may be omitted.

  In the above-described embodiment, the case where the total pitch is measured has been described. However, the present invention is not limited to this, and when the width of the belt-like regions A and B is measured, the position of the border between the belt-like regions A and B and the meandering are determined. The present invention can be widely applied to the measurement of the dimensions related to the areas A and B when measuring.

  In the above-described embodiment, the case where the dimension is measured for the pattern phase difference film in which the regions A and B which are the first and second regions having different slow axis directions are repeated has been described. Not limited to this, the point is widely used when measuring dimensions related to the first and second regions of the optical film by the retardation layer having the first and second regions having different slow axis directions. Can be applied.

  In the above-described embodiment, the case where the alignment layer, the retardation layer, the adhesive layer, and the separator film are sequentially disposed on the base material has been described. However, the present invention is not limited to this, and one surface of the base material is provided. The present invention can also be widely applied when an alignment layer and a retardation layer are provided and an adhesive layer and a separator film are disposed on the other surface of the substrate. In this case, the measurement light is incident from the phase difference layer side, and the dimensions are measured by the reflected light.

  In the above-described embodiment, the case where the present invention is applied to an optical film in which a retardation layer is provided on a substrate made of a transparent film has been described. However, the present invention is not limited thereto, and a laminate including a PET film is used. It can be widely applied when measuring an optical film provided with a retardation layer.

  In the above-described embodiment, the case where the dimension is measured in-line has been described. However, the present invention is not limited to this, and can be widely applied to a case where a test piece for inspection is separately obtained and measured. .

  In the above-described embodiment, the case where the dimensions of the band-like regions A and B are measured by applying to the pattern retardation film is described. However, the present invention is not limited to this, and the rectangular region is formed instead of the belt-like region. In addition, the present invention can be widely applied to the case where the dimensions related to the regions A and B having the rectangular shape are measured by applying to the optical film having the regions A and B.

DESCRIPTION OF SYMBOLS 1 Pattern phase difference film 2 Base material 3 Orientation layer 4 Phase difference layer 7 Pattern phase difference film original fabric 10 Light source 11 Measuring device 12 Guide roll 13, 15 Linearly polarizing plate 14 1/4 wavelength plate 16 Imaging device 17 Computer

Claims (5)

In the measurement method of an optical film in which a retardation film having first and second regions having different slow axis directions is provided on a transparent film material or a laminate including a PET film,
A linearly polarized light and monochromatic light are incident obliquely on the optical film, and reflected light is incident through the linear polarizing plate to image the optical film, thereby providing contrast in the first and second regions. Get different imaging results,
A method for measuring an optical film, which performs image processing on the imaging result and measures dimensions related to the first and second regions. The optical film measuring method according to claim 1, wherein a quarter-wave plate is provided on the optical film side of the linearly polarizing plate. The method for measuring an optical film according to claim 1, wherein the optical film is a pattern retardation film. About the optical film in which the retardation layer having the first and second regions having different slow axis directions is provided in the laminate including the transparent film material or the PET film, the first and second regions. In the optical film measuring device that measures the dimensions,
Linearly polarized light, optical system on the light source side that obliquely enters measurement light by monochromatic light on the optical film,
An imaging-side optical system that acquires an imaging result from reflected light of the measurement light,
The optical system on the light source side
A light source that emits monochromatic measuring light;
A linear polarizing plate that converts measurement light emitted from the light source into measurement light by linear polarization;
The imaging side optical system is:
A quarter-wave plate that transmits the reflected light from the optical film;
A linearly polarizing plate that transmits the transmitted light of the quarter-wave plate;
An imaging device that receives the light transmitted through the linearly polarizing plate and outputs an imaging result; and
The optical film measuring device comprises:
An optical film measuring device that acquires a measurement result of the dimension by image processing of an imaging result obtained by the imaging device. In the method for producing an optical film in which a retardation film having first and second regions having different slow axis directions is provided on a transparent film material or a laminate including a PET film,
Linearly polarized light, monochromatic light measurement light is obliquely incident on the optical film, and reflected light is imaged through a linear polarizing plate to obtain imaging results having different contrasts in the first and second regions,
Processing the imaging result to measure a dimension related to repetition of the first and second regions;
An optical film manufacturing method that manages the manufacturing process of the optical film according to a measurement result.

Images