JP5923918B2 - Attaching polarizing film - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a polarizing film sticking method for sticking a polarizing film to the front and back surfaces of a liquid crystal panel, and particularly to sticking a polarizing film that improves the bonding accuracy of the polarizing film and prevents the display contrast of the liquid crystal panel from being lowered. Regarding the method.

  FIG. 5 is a schematic cross-sectional view showing a liquid crystal panel. FIG. 5 shows a TN liquid crystal panel. As shown in FIG. 5, the liquid crystal panel 10 of the liquid crystal display device is composed of a pair of transparent substrates 11 and 12 and a liquid crystal layer 13 therebetween, and on the surface of the transparent substrates 11 and 12 on the liquid crystal layer side, The alignment films 14 and 15 are formed, respectively. The alignment films 14 and 15 are aligned in a specific direction within a plane orthogonal to the stacking direction of the two transparent substrates 11 and 12 and the liquid crystal layer 13. For example, in an IPS type liquid crystal panel, The pair of alignment films 14 and 15 are provided so that their alignment axes are parallel to each other. In the TN liquid crystal panel, the alignment axes are provided so as to be orthogonal to each other. . And the polarizing film is affixed on the surface of the transparent substrates 11 and 12, and the polarization axis of each polarizing film is parallel to the alignment axis of the alignment films 14 and 15 formed on the transparent substrates 11 and 12 to be adhered, respectively. It is adjusted to become.

  When the polarizing film is bonded to the liquid crystal panel 10, for example, as shown in FIG. 6, the polarizing films 3 and 4 are cut according to the dimensions of the liquid crystal panel 10 by a cutting machine such as a cutter, and the polarizing film is cut. 3 and 4 are positioned and attached to the outer frame of the liquid crystal panel 10 as they are. However, when this method is adopted, since the polarizing films 3 and 4 are attached without confirming the direction of the polarizing axes of the polarizing films 3 and 4, the alignment axis of the alignment film of the liquid crystal panel 10 and the polarizing film 3 , 4 in the direction of the polarization axis, for example, there is a problem that the monochrome contrast of the liquid crystal display device is lowered.

  In order to solve this problem, for example, in Patent Document 1, a light source is provided below the liquid crystal panel fixing base, and the amount of light transmitted through the polarizing film is measured by a holder that holds the polarizing film to be attached. A polarizing film pasting device provided with a photometer is disclosed. In this Patent Document 1, the light emitted from the light source is transmitted through the liquid crystal panel (and the polarizing film on the back side), then transmitted through the polarizing film to be pasted, and the amount of transmitted light is measured with a photometer, By rotating the polarizing film to be applied in a plane perpendicular to the optical axis so that the amount of transmitted light is maximized or minimized, the alignment axis of the alignment film and the polarization axis of the polarizing film are parallel. Detected.

JP 2002-14347 A

  However, in the polarizing film sticking device of Patent Document 1, the step of sticking the polarizing film to both surfaces of the liquid crystal panel is divided into two steps, and the amount of transmitted light is measured in each step. There is a problem that the sticking tact time of the polarizing film becomes long.

  This invention is made | formed in view of this problem, Comprising: It aims at providing the sticking method of the polarizing film which can stick a polarizing film to a liquid crystal panel easily and with high precision.

In the method for attaching a polarizing film according to the present invention, a first polarizing film having a first polarizing axis and a second polarizing film having a second polarizing axis are attached to the front and back surfaces of a liquid crystal panel, respectively. In the method of attaching a polarizing film,
Placing the first polarizing film and the second polarizing film facing each other before the first light source that emits illumination light; and
Observing the first and second polarizing films from the front of the first polarizing film, irradiating illumination light from the first light source toward the first and second polarizing films, Of the polarizing film and the second polarizing film, one polarizing film is fixed, and the other polarizing film is rotated around an axis perpendicular to the surface thereof, and the illumination light transmitted through these two polarizing films. Determining the positional relationship between the first and second polarizing films so that the amount of light is maximized or minimized,
When the amount of illumination light transmitted through the first and second polarizing films is maximum or minimum, marks indicating the positional relationship between the first and second polarizing films are marked with the first and second polarizing films. A process attached to
Attaching the first polarizing film and the second polarizing film to the front and back surfaces of the liquid crystal panel using the mark as an index; and
Have
The steps of attaching the first polarizing film and the second polarizing film to the front and back surfaces of the liquid crystal panel,
The second polarizing film and the liquid crystal panel face each other in front of a second light source that emits illumination light having a polarization direction parallel to or orthogonal to the alignment axis of the alignment film on the rear surface side of the liquid crystal panel. A process of arranging them together,
The amount of illumination light transmitted through the second polarizing film and the liquid crystal panel by emitting the illumination light from the second light source and rotating the second polarizing film around an axis perpendicular to the surface thereof Positioning the second polarizing film with respect to the liquid crystal panel so that is maximized or minimized,
Attaching the second polarizing film to the back surface of the liquid crystal panel;
A step of attaching the first polarizing film to the surface of the liquid crystal panel using the mark as an index .

  In the present invention, the step of forming a mark indicating a positional relationship on the two polarizing films is to form a directional mark on, for example, the first polarizing film and the second polarizing film. Alternatively, the step of forming the mark indicating the positional relationship on the two polarizing films is to form a plurality of dots and / or circular marks on the first polarizing film and the second polarizing film, respectively. The directionality can be recognized from the positional relationship between these marks.

The other polarizing film sticking method according to the present invention includes a first polarizing film having a first polarizing axis and a second polarizing film having a second polarizing axis on the front and back surfaces of a liquid crystal panel, respectively. In the attaching method of the polarizing film to be attached,
Attaching the mark for alignment to each of the first polarizing film and the second polarizing film;
Placing the first polarizing film and the second polarizing film facing each other before the first light source that emits illumination light; and
Observing the first and second polarizing films from the front of the first polarizing film, irradiating illumination light from the first light source toward the first and second polarizing films, Of the polarizing film and the second polarizing film, one polarizing film is fixed, and the other polarizing film is rotated around an axis perpendicular to the surface thereof, and the illumination light transmitted through these two polarizing films. Determining the positional relationship between the first and second polarizing films so that the amount of light is maximized or minimized,
The relative positional relationship between the mark on the first polarizing film and the mark on the second polarizing film is detected when the amount of illumination light transmitted through the first and second polarizing films is maximum or minimum. And a process of
The first polarizing film and the second polarizing film are arranged on the front and back surfaces of the liquid crystal panel so that the detected relative positional relationship is established between the marks of the first and second polarizing films. A process of applying,
Have
The steps of attaching the first polarizing film and the second polarizing film to the front and back surfaces of the liquid crystal panel,
The second polarizing film and the liquid crystal panel face each other in front of a second light source that emits illumination light having a polarization direction parallel to or orthogonal to the alignment axis of the alignment film on the rear surface side of the liquid crystal panel. A process of arranging them together,
The amount of illumination light transmitted through the second polarizing film and the liquid crystal panel by emitting the illumination light from the second light source and rotating the second polarizing film around an axis perpendicular to the surface thereof Positioning the second polarizing film with respect to the liquid crystal panel so that is maximized or minimized,
Attaching the second polarizing film to the back surface of the liquid crystal panel;
A step of attaching the first polarizing film to the surface of the liquid crystal panel using the mark as an index .

If this, for example, as the first light source and the second light source, it is possible to use back light of a liquid crystal display device.

  In the present invention, the first and second polarizing films are irradiated so that the illumination light is emitted from the first light source, and the amount of transmitted light transmitted through the two polarizing films is maximized or minimized. The positional relationship is determined, and marks indicating the positional relationship are formed on the first and second polarizing films, respectively. Therefore, by simply sticking two polarizing films to the front and back surfaces of the liquid crystal panel using this mark as an indicator, the direction of the polarization axis is accurately adjusted between the polarizing films, and the polarizing films can be attached easily. is there.

(A) is a figure which shows the alignment process between polarizing films in the sticking method of the polarizing film which concerns on 1st Embodiment of this invention, (b) is a figure which shows the mark formed in two polarizing films, (c) is a figure which shows the sticking process of the polarizing film to a liquid crystal panel. (A) thru | or (c) is a figure which shows the case where a dot or a circular mark is provided in two polarizing films in the sticking method of the polarizing film which concerns on 1st Embodiment. (A) is a figure which shows the alignment process between polarizing films in the sticking method of the polarizing film which concerns on 2nd Embodiment of this invention, (b) is the relative of the mark provided in two polarizing films. It is a figure which shows a positional relationship. (A) is a figure which shows the alignment process between polarizing films in the sticking method of the polarizing film which concerns on 3rd Embodiment of this invention, (b) is a figure which shows the mark formed in two polarizing films, (c) is a figure which shows the sticking process of the polarizing film to a liquid crystal panel. It is a typical sectional view of a liquid crystal panel. It is a figure which shows the pasting method of the conventional polarizing film.

Embodiments of the present invention will be described below. FIG. 1A is a diagram showing an alignment process between polarizing films in the polarizing film sticking method according to the first embodiment of the present invention, and FIG. 1B is a diagram showing marks formed on two polarizing films. FIG. 1C is a diagram showing a step of attaching a polarizing film to the liquid crystal panel. The present invention applies a polarizing film to which a first polarizing film 3 having a first polarizing axis and a second polarizing film 4 having a second polarizing axis are attached to the front and back surfaces of a liquid crystal panel 10, respectively. In the method, a step of arranging the first polarizing film 3 and the second polarizing film 4 so as to face each other before the light source 5 that emits illumination light, and a first and a second from the front of the first polarizing film 3 The second polarizing films 3 and 4 are observed, illumination light is irradiated from the light source 5 toward the first and second polarizing films 3 and 4, and the first polarizing film 3 and the second polarizing film 4 One polarizing film is fixed, and the other polarizing film is rotated around an axis perpendicular to the surface so that the amount of illumination light transmitted through the two polarizing films 3 and 4 is maximized or minimized. , First and second polarizing films 3, When the amount of illumination light transmitted through the two polarizing films 3 and 4 is maximum or minimum, a mark indicating the positional relationship is first displayed on each of the two polarizing films 3 and 4. And attaching the first polarizing film 3 and the second polarizing film 4 to the front and back surfaces of the liquid crystal panel using the mark as an index. is there. In this embodiment, the case where the liquid crystal panel to which the polarizing film is attached is a TN type liquid crystal panel 10 will be described. That is, in this embodiment, the 1st polarizing film 3 is stuck on the surface of the liquid crystal panel 10, and the 1st polarizing film 3 and the 2nd polarizing film 4 with which a polarizing axis orthogonally crosses on the back surface of the liquid crystal panel 10. Affix.

  As shown in FIG. 5, the liquid crystal panel 10 to which the polarizing film is attached is composed of a pair of transparent substrates 11 and 12 and a liquid crystal layer 13 therebetween. Alignment films 14 and 15 are formed on the surfaces, respectively. The alignment films 14 and 15 are aligned in a specific direction within a plane orthogonal to the stacking direction of the two transparent substrates 11 and 12 and the liquid crystal layer 13. The alignment axes are provided so as to be orthogonal to each other. That is, the transparent substrate 11 positioned on the front side of the liquid crystal panel 10 is formed with an alignment film 14 having an alignment axis parallel to the column direction of the pixel arrangement of the liquid crystal panel 10, and is positioned on the back side of the liquid crystal panel 10. An alignment film 15 having an alignment axis parallel to the row direction of the pixel array of the liquid crystal panel 10 is formed on the transparent substrate 12.

  The first and second polarizing films 3 and 4 are, for example, a base material containing a polarizing element made of iodine or a dichroic dye, whose both surfaces are protected by a protective material made of TAC (triacetyl cellulose) or the like. Yes, an adhesive for applying to the liquid crystal panel 10 is applied to one surface of the protective material. Each of the polarizing films 3 and 4 has a polarization axis in a specific direction, and transmits light having a component parallel to the polarization axis when irradiated with illumination light. In the present embodiment, the polarizing films 3 and 4 are attached in parallel with the alignment axes of the alignment films 14 and 15 formed on the transparent substrates 11 and 12 of the liquid crystal panel 10.

  Next, a method for attaching the first and second polarizing films to the liquid crystal panel 10 having the above configuration will be described. In this embodiment, first, before the 1st light source 5 which radiate | emits illumination light, the 1st polarizing film 3 and the 2nd polarizing film 4 are arrange | positioned facing each other. As shown in FIG. 1A, the first light source 5 is a light source that emits non-polarized illumination light, for example, and an LED, a fluorescent lamp, or the like can be used. As the first light source 5, for example, a surface light source capable of irradiating illumination light on the entire surfaces of the first and second polarizing films 3 and 4 can be used, but the size thereof is not particularly limited. In the case where the first light source 5 is a light source that emits illumination light having only a polarization component orthogonal to the polarization direction of the second polarizing film 4, the illumination light emitted from the first light source 5 is the second light source. However, if the illumination light is other than that, it has a polarization component parallel to the polarization direction of the second polarization film 4, so that the illumination light is transmitted to the second polarization film 4. Can be made. Therefore, as the first light source 5, for example, a backlight of a liquid crystal display device can be used in addition to a light source that emits non-polarized illumination light such as an LED and a fluorescent lamp.

  Next, in the state where the second polarizing film 4 is fixed as it is, the first light source 5 emits non-polarized illumination light toward the first and second polarizing films 3 and 4, and the illumination light is emitted. The light is transmitted through the second polarizing film 4 and the first polarizing film 3. In this state, while rotating the first polarizing film 3 around an axis perpendicular to the surface, the transmitted light of the two polarizing films 3 and 4 is observed with the camera 6 or the like, and based on the observed image. Measure the amount of transmitted light.

And when the light quantity of the illumination light which permeate | transmitted the 1st and 2nd polarizing film became the minimum, rotation of the 1st polarizing film 3 is stopped. The light emitted from the first light source 5 and transmitted through the second polarizing film 4 becomes linearly polarized light parallel to the polarization axis of the second polarizing film 4, and this light is applied to the first polarizing film 3. Thereby, only the component parallel to the polarization axis of the first polarizing film 3 out of the transmitted light of the second polarizing film 4 is transmitted to the first polarizing film 3. Therefore, in this embodiment, when the polarization axis of the first polarizing film 3 and the polarization axis of the second polarizing film 4 are in a state of being orthogonal to each other, both of the two polarizing films 3 and 4 are transmitted. The amount of illumination light is almost zero. Therefore, as shown in FIG. 1B, the observation image on the camera side is in a state where the color tone is closest to black.

After stopping the rotation of the first polarizing film 3, marks 3a and 4a indicating the positional relationship are formed on the two polarizing films 3 and 4, respectively. As shown in FIG. 1B, these marks 3a and 4a are linear marks extending with an inclination with respect to the polarization axes of the first and second polarizing films 3 and 4, for example. The mark 3a formed on the polarizing film 3 and the mark 4a formed on the second polarizing film 4 are parallel to each other, and are separated by a distance a when viewed from the direction perpendicular to the surfaces of the polarizing films 3 and 4. Yes.

  Next, as shown in FIGS. 1B and 1C, the first and second polarizing films 3 and 4 are attached to the front and back surfaces of the liquid crystal panel 10 using the marks 3a and 4a as indexes. In the present embodiment, the first and second polarizing films 3 and 4 are formed with marks 3a and 4a indicating the positional relationship, respectively, so that two polarizing films are used with the marks 3a and 4a as indices. 3 and 4 can be easily attached to the front and back surfaces of the liquid crystal panel 10, respectively.

In the conventional polarizing film attaching step, the cut polarizing films 3 and 4 are attached to the outer frame of the liquid crystal panel 10 as they are, and the direction of the polarization axis of the polarizing films 3 and 4 is applied. Since the polarizing films 3 and 4 are affixed to the liquid crystal panel 10 without confirming the above, the polarization axis is shifted between the first polarizing film 3 and the second polarizing film 4, and the contrast is lowered. There was a problem that it occurred.

However, in the present embodiment, since the marks 3a and 4a indicating the positional relationship between the first and second polarizing films 3 and 4 are provided, the polarizing films 3 and 4 are respectively used as indicators for the liquid crystal panel 10. By simply sticking to the front and back surfaces, the polarization axis does not deviate between the two polarizing films 3 and 4, and a reduction in contrast can be prevented.

  In this attaching step, first, the second polarizing film 4 is positioned and attached to the liquid crystal panel 10, and then the first polarizing film 3 is attached to the liquid crystal panel 10 using the marks 3a and 4a as indices. It is preferable. In this case, first, before the second light source 2 that emits illumination light, the second polarizing film 4 and the liquid crystal panel 10 are arranged to face each other, and the illumination light is emitted from the second light source 2. The light is emitted, the second polarizing film 4 is rotated about an axis perpendicular to the surface thereof, and the amount of illumination light transmitted through the second polarizing film 4 and the liquid crystal panel 10 is observed by, for example, a camera. As the second light source 2, the polarization axis of the second polarizing film 4 when the second polarizing film 4 is stuck at a predetermined position on the back surface of the liquid crystal panel 10 (the alignment film 15 on the back side of the liquid crystal panel 10 ( A light source that emits illumination light having a polarization direction parallel or perpendicular to the orientation axis) of FIG. 5) can be used. For example, a liquid crystal display fixed to the back side of the liquid crystal panel 10 when assembling the display device A device backlight can be used.

  For example, as the second light source 2, illumination light having a polarization direction parallel to the alignment axis of the alignment film 15 on the back surface side of the liquid crystal panel 10, for example, as shown in FIG. Use illumination light. As such a second light source 2, as described above, a backlight of a liquid crystal display device can be used. With respect to such a second light source 2, the second polarizing film 4 is rotated around an axis perpendicular to the surface thereof, and the amount of illumination light transmitted through the second polarizing film 4 and the liquid crystal panel 10 is maximized. The position of the second polarizing film 4 is determined so that That is, when the second polarizing film 4 is rotated around an axis perpendicular to the surface, the polarization axis of the second polarizing film 4 is parallel to the polarization direction of the illumination light. The amount of light transmitted through the polarizing film 4 is maximized. Further, since the polarization direction of the illumination light from the second light source 2 is parallel to the alignment axis of the alignment film 15 on the back surface side of the liquid crystal panel 10, the amount of illumination light transmitted through the liquid crystal panel 10 is also maximized. Therefore, the amount of illumination light observed by the camera is maximized. At this position, the second polarizing film 4 is attached to the back surface of the liquid crystal panel 10.

  When the polarization axis of the second polarizing film 4 attached to the back surface of the liquid crystal panel 10 is inclined with respect to the alignment axis of the alignment film 15 on the back surface side of the liquid crystal panel 10, the second polarizing film The illumination light transmitted through the liquid crystal panel 10 and the liquid crystal panel 10 is slightly reduced in light amount, but the illumination light is irradiated and the second polarizing film 4 is rotated to measure the transmitted light amount as in this embodiment. By doing so, it is possible to accurately detect that the alignment axis of the alignment film 15 and the polarization axis of the second polarizing film 4 are parallel to each other when the amount of transmitted light is maximized.

  When the illumination light having the polarization direction orthogonal to the alignment axis of the alignment film 15 on the back surface side of the liquid crystal panel 10 is used as the second light source 2, the second polarizing film 4 is attached at the following position. To be determined. That is, when the second polarizing film 4 is rotated around an axis perpendicular to the surface thereof, the second polarizing film 4 has a polarization axis that is perpendicular to the polarization direction of the illumination light. The amount of light transmitted through the polarizing film 4 is minimized. At this time, the polarization axis of the second polarizing film 4 is parallel to the alignment axis of the alignment film 15 on the back surface side of the liquid crystal panel 10. And the light quantity of the illumination light observed with a camera becomes the minimum. At this position, the second polarizing film 4 is attached to the back surface of the liquid crystal panel 10. Even in this case, it can be accurately detected by the amount of transmitted light that the alignment axis of the alignment film 15 and the polarization axis of the second polarizing film 4 are parallel to each other.

  Next, the first polarizing film 3 is attached to the surface of the liquid crystal panel 10. In the present embodiment, a case where illumination light having a polarization direction parallel to the alignment axis of the alignment film 15 on the back surface side of the liquid crystal panel 10 is used as the second light source 2 will be described. At this time, when viewed from a direction perpendicular to the surface of the polarizing film, the mark 3a provided on the first polarizing film 3 has a predetermined positional relationship with respect to the mark 4a provided on the second polarizing film 4. The 1st polarizing film 3 is stuck so that it may become. This predetermined positional relationship is, for example, the positional relationship when the marks 3a and 4a are formed. As shown in FIG. 1B, the linear marks 3a and 4a are parallel to each other, and the polarizing film 3, When viewed from the direction perpendicular to the surface of No. 4, the distance a is separated.

  Thus, in the attaching process of the polarizing films 3 and 4, first, the second polarizing film 4 is positioned and attached to the liquid crystal panel 10, and then the first polarizing film is used with the marks 3a and 4a as indices. 3 is affixed to the liquid crystal panel 10 so that the alignment axes 14 and 15 of the liquid crystal panel 10 are adjusted so that the polarization axes of the first and second polarizing films 3 and 4 are parallel with high accuracy. For example, it is possible to more effectively prevent the monochrome contrast of the liquid crystal display device from being lowered.

  As described above, in the present embodiment, the polarizing films 3 and 4 are formed with the marks 3a and 4a, respectively, and the polarizing film 3 is simply attached using the marks 3a and 4a as an index. When viewed from a direction perpendicular to the surface of the first polarizing film 3, the polarization axis of the first polarizing film 3 is adjusted to a direction orthogonal to the polarizing axis of the second polarizing film 4. Therefore, the polarization axis of the first polarizing film 3 and the alignment axis of the alignment film 14 on the surface side of the liquid crystal panel 10 can be reliably made parallel, and the display contrast of the liquid crystal panel due to the bonding accuracy of the polarizing film. Can be reliably prevented. In addition, since the first polarizing film 3 is simply attached so that the linear marks 3a and 4a are parallel to each other, the polarizing film 3 can be easily attached. There will be no long-term.

  Next, the operation of the liquid crystal panel to which the polarizing film is attached by the attaching method of this embodiment will be described. The liquid crystal panel 10 having the first and second polarizing films 3 and 4 attached to the front and back surfaces, for example, has a plurality of scan electrodes and sustain electrodes arranged alternately in the row direction and a plurality of data in the column direction. Electrodes are arranged, and one pixel is formed at the intersection of the scan electrode, the sustain electrode, and the data electrode. A second light source 2 such as a backlight is disposed on the back side of the liquid crystal panel 10 and emits, for example, non-polarized illumination light. The liquid crystal molecules in the liquid crystal layer 13 are aligned in a specific direction by the voltage applied to each electrode, and the amount of display light to be transmitted can be adjusted according to each pixel.

  The illumination light emitted from the backlight (second light source 2) first passes through the second polarizing film 4 and the alignment film 15 of the liquid crystal panel 10, and then the polarization direction of the polarizing film 4 and the alignment film 15 alignment. Depending on the direction, the light is incident on the liquid crystal layer 13 while being polarized in a specific direction within a plane perpendicular to the optical axis. In the present embodiment, the second polarizing film 4 attached to the back surface of the liquid crystal panel 10 is attached so that the polarization axis thereof is parallel to the alignment axis of the alignment film 15 with high accuracy. Illumination light incident on the liquid crystal layer 13 has a polarization direction in a plane orthogonal to the optical axis thereof parallel to both the polarization axis of the polarizing film 4 and the alignment axis of the alignment film 15.

The liquid crystal molecules in the liquid crystal layer 13 are aligned in a specific direction by the voltage applied between the electrodes according to each pixel, and the light incident on the liquid crystal layer 13 is polarized by the alignment direction of the liquid crystal molecules. The direction changes. For example, when white display is performed in a certain pixel, a voltage is applied so that the liquid crystal molecules are twisted by 90 ° from the back surface side to the front surface side of the liquid crystal panel 10, and when black display is performed, the liquid crystal molecules are A voltage that is aligned in the same direction as the thickness direction of the liquid crystal panel is applied. Then, the light transmitted through the liquid crystal layer 13 enters the alignment film 14 and the first polarizing film 3. The incident light is transmitted through the alignment film 14 and the first polarizing film 3 only by the components parallel to the alignment axis of the alignment film 14 and the polarization axis of the first polarizing film 3, respectively. It becomes. Therefore, at this time, when the alignment axis of the alignment film 14 and the polarization axis of the first polarizing film 3 are not parallel to each other, the amount of display light is reduced and the display contrast of the liquid crystal panel is lowered. However, in the present embodiment, the first polarizing film 3 attached to the surface of the liquid crystal panel 10 is attached so that the polarization axis thereof is parallel to the alignment axis of the alignment film 14 with high accuracy. For this reason, the display contrast does not decrease regardless of whether the display of each pixel is white display or black display.

  Thus, according to the present embodiment, the polarizing films 3 and 4 can be easily attached, and the polarizing films 3 and 4 can be attached to the front and back surfaces of the liquid crystal panel 10 with high accuracy. A decrease in display contrast can be reliably prevented.

  In the present embodiment, the case where the marks 3a and 4a are each linear has been described. However, the shape of the mark is an example, and the present invention is not limited to this aspect. For example, the shape of the marks 3a and 4a may be a polygon such as a cross or a rectangle, or an ellipse. Further, the shape of the marks 3a and 4a may be a point or a circle. However, when the number of the dots or the circle is one, the first polarizing film 3 and / or the second polarizing film 4 is rotated. Even in this case, since the positional relationship between the mark provided on the first polarizing film 3 and the mark provided on the second polarizing film 4 can be maintained, the first polarizing film 3 and / or the first polarizing film 3 can be maintained. It may not be possible to recognize that the polarizing film 4 of 2 is rotated, and the polarizing film 3 and / or 4 may be stuck on the surface of the liquid crystal panel 10 in a rotated state. Therefore, in the case of providing a dot or a circular mark, if a plurality of these marks are provided on the first polarizing film 3 and the second polarizing film 4, respectively, the directionality is determined from the positional relationship between these marks. If the positions of the first polarizing film 3 and the second polarizing film 4 are adjusted so that the corresponding marks have a predetermined positional relationship, the effects of the present invention can be obtained. .

FIG. 2 is a diagram showing a case where dots or circular marks 3b and 4b are provided on two polarizing films 3 and 4 in the polarizing film sticking method according to the first embodiment. As shown in FIG. 2 (a), in this modification, in the step of providing two polarizing films 3 and 4, circular marks 3b and 3c are provided on the first polarizing film, and the second polarizing film is provided. In FIG. 4, dot-like marks 4b and 4c are provided in the vicinity of the diagonal of the polarizing films 3 and 4, respectively. At this time, when viewed from the direction perpendicular to the surfaces of the polarizing films 3 and 4, the dotted marks 4 b and 4 c provided on the second polarizing film 4 are circular marks 3 b and 3 c provided on the first polarizing film 3, respectively. Each mark is provided so as to be located at the center of the mark. And in the process of sticking the 1st polarizing film 3 on the surface of the liquid crystal panel 10, seeing from the direction perpendicular | vertical to the surface of the polarizing films 3 and 4, the center of the circular marks 3b and 3c is the dotted | punctate marks 4b and 4c. The first polarizing film 3 is attached to the surface of the liquid crystal panel 10 by adjusting the position of the first polarizing film 3 so as to coincide with the above. At this time, as shown in FIG. 2 (c) , even if the mark 4b is located at the center of the mark 3b, the relative position between the mark 3c and the mark 4b when the first polarizing film 3 is rotated. Since the relationship is shifted, it can be detected that the first polarizing film 3 is rotating. Therefore, the third polarizing film 3 is rotated so that the centers of the circular marks 3b and 3c coincide with the dotted marks 4b and 4c, and the first polarizing film 3 is attached to the surface of the liquid crystal panel 10. For example, it is possible to prevent a decrease in black and white contrast of a liquid crystal display device.

  Next, the polarizing film sticking method according to the second embodiment of the present invention will be described. FIG. 3A is a diagram showing an alignment process between polarizing films in the polarizing film attaching method according to the second embodiment of the present invention, and FIG. 3B is provided on two polarizing films. It is a figure which shows the relative positional relationship of a mark. As shown in FIG. 3A, in the present embodiment, before the relative alignment between the first polarizing film 3 and the second polarizing film 4, each polarizing film 3, 4 is used for alignment. The linear marks 3d and 4d are attached.

  In the present embodiment, when the first polarizing film 3 and the second polarizing film 4 are aligned relative to each other, the relative positional relationship between the marks 3d and 4d previously provided on the polarizing films 3 and 4 is set. Is observed with a camera, for example. That is, as shown in FIG. 3B, when the color tone of the observation image on the camera side is closest to black, for example, the mark 3d of the first polarizing film 3 and the mark of the second polarizing film 4 4d are parallel to each other, and are separated by a distance a when viewed from a direction perpendicular to the surfaces of the polarizing films 3 and 4.

  In the present embodiment, when the polarizing films 3 and 4 are affixed to the liquid crystal panel 10, the above-described relative detection of the mark 3d of the first polarizing film 3 and the mark 4d of the second polarizing film 4 by the camera. The position of the 1st polarizing film 3 is adjusted so that it may become a target positional relationship. Thereby, the effect similar to 1st Embodiment is acquired.

  In the present embodiment, the shapes of the marks 3d and 4d formed in advance on the two polarizing films can be modified in the same manner as in the first embodiment.

  Next, the polarizing film sticking method according to the third embodiment of the present invention will be described. FIG. 4A is a diagram showing an alignment process between polarizing films in the polarizing film attaching method according to the third embodiment of the present invention, and FIG. 4B is a diagram showing marks formed on two polarizing films. FIG. 4C is a diagram showing a step of attaching a polarizing film to the liquid crystal panel. In the first embodiment, the case where the liquid crystal panel to which the polarizing film is attached is the TN liquid crystal panel 10, but in this embodiment, the liquid crystal panel to which the polarizing film is attached is an IPS type. The liquid crystal panel 100 of FIG. That is, the first polarizing film 7 attached to the front surface of the liquid crystal panel 100 is attached so that the polarization axis thereof is parallel to the polarization axis of the second polarizing film 4 attached to the back surface. About another structure, it is the same as that of 1st Embodiment.

  Next, a method for attaching the first and second polarizing films to the liquid crystal panel 100 will be described. Also in this embodiment, first, before the 1st light source 5 which radiate | emits illumination light, the 1st polarizing film 7 and the 2nd polarizing film 4 are arrange | positioned facing each other. Then, with the second polarizing film 4 fixed, non-polarized illumination light is emitted from the first light source 5, and the illumination light is transmitted through the second polarizing film 4 and the first polarizing film 7. In this state, the transmitted light of the two polarizing films 7 and 4 is observed with the camera 6 or the like while rotating the first polarizing film 7 about an axis perpendicular to the surface, and based on the observed image. Measure the amount of transmitted light.

In the present embodiment, the rotation of the first polarizing film 7 is stopped when the amount of illumination light transmitted through the first and second polarizing films becomes maximum. The light emitted from the first light source 5 and transmitted through the second polarizing film 4 becomes linearly polarized light parallel to the polarization axis of the second polarizing film 4, and this light is applied to the first polarizing film 7. Thereby, only the component parallel to the polarization axis of the first polarizing film 7 out of the transmitted light of the second polarizing film 4 is transmitted to the first polarizing film 7. Therefore, in this embodiment, when the polarization axis of the first polarizing film 7 and the polarization axis of the second polarizing film 4 are parallel, the amount of illumination light transmitted through both of the two polarizing films 7 and 4 Is the maximum, and as shown in FIG. 4B, the observation image on the camera side has a color tone closest to white.

  Then, after stopping the rotation of the first polarizing film 7, marks 7 a and 4 a indicating the positional relationship are formed on the two polarizing films 7 and 4, respectively. The shape and arrangement of the marks 7a and 4a are the same as in the first embodiment.

  Next, the first and second polarizing films 7 and 4 are attached to the front and back surfaces of the liquid crystal panel 100 using the marks 7a and 4a as indexes. In this attaching step, first, the second polarizing film 4 is attached to the back surface of the liquid crystal panel 100. The attaching process of the first polarizing film 4 is the same as that in the first embodiment. As the second light source 2, as described above, a light source that emits illumination light having a polarization direction parallel or orthogonal to the alignment axis of the alignment film 15 on the back surface side of the liquid crystal panel 10 can be used. When the display device is assembled, a backlight of the liquid crystal display device fixed to the back surface side of the liquid crystal panel 10 can be used.

  When the polarization axis of the second polarizing film 4 attached to the back surface of the liquid crystal panel 100 is inclined with respect to the alignment axis of the alignment film 15 on the back surface side of the liquid crystal panel 100, the second polarizing film 4 and Although the amount of illumination light transmitted through the liquid crystal panel 100 is slightly reduced, the amount of transmitted light is measured while irradiating illumination light and rotating the second polarizing film 4 as in this embodiment. Thus, it is possible to accurately detect that the alignment axis of the alignment film 15 and the polarization axis of the second polarizing film 4 are parallel to each other when the amount of transmitted light reaches a maximum.

  Next, the first polarizing film 3 is attached to the surface of the liquid crystal panel 100. At this time, when viewed from a direction perpendicular to the surface of the polarizing film, the mark 7a provided on the first polarizing film 7 has a predetermined positional relationship with respect to the mark 4a provided on the second polarizing film 4. The 1st polarizing film 7 is stuck so that it may become.

  Also in the present embodiment, the marks 7a and 4a are formed on the two polarizing films 7 and 4, respectively, and the polarizing film 7 is attached using the marks 7a and 4a as an index, so that the surface is perpendicular to the surface of the polarizing film. When viewed from the direction, the polarization axis of the first polarizing film 7 is adjusted in parallel with the polarization axis of the second polarizing film 4. Therefore, the polarization axis of the first polarizing film 7 and the alignment axis of the alignment film 14 on the surface side of the liquid crystal panel 10 can be reliably made parallel. Therefore, also in the present embodiment, it is possible to prevent the display contrast of the liquid crystal panel from being lowered due to the bonding accuracy of the polarizing film, and the first polarizing film 7 is attached between the linear marks 7a and 4a. Is only adjusted to be parallel, so that the polarizing film 7 can be attached easily, and the attaching tact time of the polarizing film is not prolonged.

  In the present embodiment, the marks provided on the two polarizing films can be variously modified in the same manner as in the first and second embodiments.

  In the first to third embodiments, the step of measuring the amount of illumination light before forming the mark 3a (3b, 3c, 3d, 7a) and the mark 4a (4b, 4c, 4d) is the second step. The polarizing film 4 is fixed and the first polarizing films 3 and 7 are rotated around an axis perpendicular to the surface. The first polarizing films 3 and 7 are fixed and the second polarizing film 4 is It may be rotated. Also in the step of attaching the first and second polarizing films 3, 7, and 4 to the liquid crystal panels 10 and 100, for example, the first polarizing films 3 and 7 are attached first, and the mark 3a (3b, 3c, 3d, 7a) and the mark 4a (4b, 4c, 4d) may be used as an index to attach the second polarizing film 4 later.

  In the production of a liquid crystal panel in which a polarizing film is attached to each of the front and back surfaces, the present invention makes it easy to attach a polarizing film by forming a mark indicating a positional relationship between the polarizing films in advance. It is possible to make the polarization axis parallel to the alignment direction of the alignment film with high accuracy, thereby reliably preventing a decrease in display contrast of the liquid crystal display device.

10: liquid crystal panel, 11, 12: transparent substrate, 13: liquid crystal layer, 14, 15: alignment film, 2: backlight, 3, 7: (first) polarizing film, 4: (second) polarizing film 5: 1st light source, 6: Camera, 3a, 3b, 3c, 3d, 4a, 4b, 4c, 4d, 7a: Mark

Claims (5)

In the method of attaching a polarizing film, the first polarizing film having the first polarizing axis and the second polarizing film having the second polarizing axis are attached to the front and back surfaces of the liquid crystal panel, respectively.
Placing the first polarizing film and the second polarizing film facing each other before the first light source that emits illumination light; and
Observing the first and second polarizing films from the front of the first polarizing film, irradiating illumination light from the first light source toward the first and second polarizing films, Of the polarizing film and the second polarizing film, one polarizing film is fixed, and the other polarizing film is rotated around an axis perpendicular to the surface thereof, and the illumination light transmitted through these two polarizing films. Determining the positional relationship between the first and second polarizing films so that the amount of light is maximized or minimized,
When the amount of illumination light transmitted through the first and second polarizing films is maximum or minimum, marks indicating the positional relationship between the first and second polarizing films are marked with the first and second polarizing films. A process attached to
Attaching the first polarizing film and the second polarizing film to the front and back surfaces of the liquid crystal panel using the mark as an index; and
Have
The steps of attaching the first polarizing film and the second polarizing film to the front and back surfaces of the liquid crystal panel,
The second polarizing film and the liquid crystal panel face each other in front of a second light source that emits illumination light having a polarization direction parallel to or orthogonal to the alignment axis of the alignment film on the rear surface side of the liquid crystal panel. A process of arranging them together,
The amount of illumination light transmitted through the second polarizing film and the liquid crystal panel by emitting the illumination light from the second light source and rotating the second polarizing film around an axis perpendicular to the surface thereof Positioning the second polarizing film with respect to the liquid crystal panel so that is maximized or minimized,
Attaching the second polarizing film to the back surface of the liquid crystal panel;
Pasting the first polarizing film on the surface of the liquid crystal panel using the mark as an index . The step of forming a mark indicating a positional relationship on the two polarizing films is to form a directional mark on the first polarizing film and the second polarizing film. Item 10. A method for attaching a polarizing film according to Item 1. The step of forming the mark indicating the positional relationship on the two polarizing films is to form a plurality of dots and / or circular marks on the first polarizing film and the second polarizing film, respectively. The polarizing film sticking method according to claim 1, wherein the directionality is recognized from a positional relationship between these marks. In the method of attaching a polarizing film, the first polarizing film having the first polarizing axis and the second polarizing film having the second polarizing axis are attached to the front and back surfaces of the liquid crystal panel, respectively.
Attaching the mark for alignment to each of the first polarizing film and the second polarizing film;
Placing the first polarizing film and the second polarizing film facing each other before the first light source that emits illumination light; and
Observing the first and second polarizing films from the front of the first polarizing film, irradiating illumination light from the first light source toward the first and second polarizing films, Of the polarizing film and the second polarizing film, one polarizing film is fixed, and the other polarizing film is rotated around an axis perpendicular to the surface thereof, and the illumination light transmitted through these two polarizing films. Determining the positional relationship between the first and second polarizing films so that the amount of light is maximized or minimized,
The relative positional relationship between the mark on the first polarizing film and the mark on the second polarizing film is detected when the amount of illumination light transmitted through the first and second polarizing films is maximum or minimum. And a process of
The first polarizing film and the second polarizing film are arranged on the front and back surfaces of the liquid crystal panel so that the detected relative positional relationship is established between the marks of the first and second polarizing films. A process of applying,
Have
The steps of attaching the first polarizing film and the second polarizing film to the front and back surfaces of the liquid crystal panel,
The second polarizing film and the liquid crystal panel face each other in front of a second light source that emits illumination light having a polarization direction parallel to or orthogonal to the alignment axis of the alignment film on the rear surface side of the liquid crystal panel. A process of arranging them together,
The amount of illumination light transmitted through the second polarizing film and the liquid crystal panel by emitting the illumination light from the second light source and rotating the second polarizing film around an axis perpendicular to the surface thereof Positioning the second polarizing film with respect to the liquid crystal panel so that is maximized or minimized,
Attaching the second polarizing film to the back surface of the liquid crystal panel;
Pasting the first polarizing film on the surface of the liquid crystal panel using the mark as an index . The method for attaching a polarizing film according to claim 1 or 4 , wherein a backlight of a liquid crystal display device is used as the first light source and the second light source.

Images