JP3996329B2 - Backlight film body and method for producing backlight film body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film body such as an optical sheet (a diffusion film, a lens film, a deflection film) or a reflection film (reflection plate) used for a backlight.
[0002]
[Prior art]
Optical sheets and reflective films used for backlights are attached to the front and back surfaces of the light guide plate. Various methods are used to fix these optical sheets and reflectors, and double-sided tape is often used. ing.
However, as the size of the liquid crystal display device increases, the frame becomes narrower, and there is a problem in fixing with a double-sided tape. For example, the size of the liquid crystal screen used in an A4 notebook type personal computer has increased from 10 inches to 14 inches. However, as the screen becomes larger, the edge of the liquid crystal display device becomes narrower (the frame is narrowed).
[0003]
Due to this narrowing of the frame, the non-display area 51 at the peripheral edge of the backlight 50 as shown in FIG. 10 is narrowed. In the non-display area 51 at the periphery of the backlight, fixing of members such as a light guide plate, an optical sheet, and a reflector, storage of a lamp tube, arrangement of light shielding printing for preventing sheet misalignment, warping, bright lines / dark lines, etc. It is used to improve the quality of
When this non-display area 51 becomes narrow, the area where the double-sided tape can be applied becomes narrow, and the application work of the double-sided tape becomes very difficult.
[0004]
In other words, the work of applying the double-sided tape to the reflector or optical sheet is performed manually or mechanically, but when the double-sided tape is attached to the reflector or optical sheet, Since the double-sided tape is extended and twisted, if the area where the double-sided tape can be applied is small, the operation becomes very difficult.
In addition, the reflector or optical sheet once attached and fixed with the double-sided tape may be peeled off again due to incorrect attachment, but at this time, the double-sided tape may be peeled off from the reflector or optical sheet, causing displacement or stretching. Problems occur.
[0005]
As described above, the double-sided tape is very difficult to cope with the narrowing of the frame.
In the present invention, it is proposed to employ glue printing instead of double-sided tape as one of the countermeasures for narrowing the frame. Since glue printing is less likely to peel off or stretch than double-sided tape, it is possible to cope with a narrow frame of the backlight.
[0006]
[Problems to be solved by the invention]
Now, the selection criteria for “glue” that bonds one member to another are: a) adhesive strength, b) peels cleanly when peeled, c) does not discolor due to light, d) does not discolor due to temperature, e) temperature -There are many items such as the adhesive strength does not change with humidity, f) the glue hardness does not change with temperature, humidity, etc., g) cost. In selecting the glue, it is necessary to consider many of these items. Therefore, there are few glues that satisfy the conditions, and much labor is required for the examination.
[0007]
Moreover, even a paste having a desired adhesive strength cannot be adopted unless other necessary conditions are satisfied, and as a result, there is a problem that various required adhesive strengths cannot be obtained.
The present invention has been made in view of such a problem, and a problem to be solved by the present invention is to easily obtain various adhesive forces.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has taken the following technical means. That is, a feature of the present invention is a backlight film body on which paste printing for application is performed, and the paste printing is a part for adjusting adhesive force in an adhesive area on which paste printing is performed. The paste printing is performed in the form of scattered dots having a substantially uniform distribution in the bonding area . If the glue printing is applied partially within the bonding area to adjust the adhesive strength, the adhesive strength can be reduced compared to the case where the glue printing is applied to the entire bonding area. Different adhesive forces can be achieved even if glue is used.
[0009]
The adhesive area as possible out to the portion corresponding to the non-display area of the backlight periphery. Even if paste printing is partially applied to the bonding area, uniform bonding force can be obtained in the bonding area by applying the paste printing in the form of scattered dots having a substantially uniform distribution.
Furthermore, it is preferable that an identification symbol for identifying the type of the film body is written by glue printing. As described above, when the identification symbol is written on the film body by glue printing, it is easy to distinguish various types of film bodies on a production line or the like. In addition, since the identification symbol is written by glue printing, the identification symbol can be marked on the film body by glue printing when performing paste printing for application, which is efficient. In addition, numbers, characters, symbols, arbitrary figures, etc. can be adopted as the identification symbols.
[0010]
Further, as another aspect of the present invention, a shrunk pattern is printed on a reflection plate as a backlight film, specifically on a contact surface of the reflection plate attached to the reflection surface side of the light guide plate with the light guide plate. As a result, unevenness can be formed. The unevenness is preferably obtained by printing a transparent shrink pattern. A feature of the manufacturing method according to the present invention is a method of manufacturing a backlight film body on which glue printing for pasting is performed, wherein the glue is applied to an adhesive area on which the paste printing of the film body is performed. When printing, an adhesive area having a desired adhesive force is formed by making the area of the glue print different from the area of the entire adhesive area, and the glue print is applied in the form of scattered dots having a substantially uniform distribution in the adhesive area. In the point.
[0011]
The adhesive strength can be increased by increasing the area of the glue print relative to the total area of the adhesive area, and the adhesive strength can be reduced by reducing the area of the adhesive print. Can be realized. In addition, as a method of performing the paste printing, a uniform adhesive force can be obtained in the adhesion area by applying it in the form of scattered dots having a substantially uniform distribution in the adhesion area. Furthermore, when performing paste printing, if an identification symbol for identifying the type of film body is applied to the film body simultaneously by glue printing, the type of film body can be identified by performing glue printing. Therefore, convenience in production lines and the like is increased.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing a schematic configuration of the backlight 1. The backlight 1 is disposed on the light guide plate 2, the optical sheet (film body) 3 disposed on the surface (light exit surface) 2 a of the light guide plate 2, and the back surface (reflection surface) 2 b of the light guide plate 2 (film). A light source (lamp) 5 is provided on one end side of the light guide plate 2.
[0013]
The light guide plate 2 is made of acrylic resin and has a rectangular shape (rectangular shape) in plan view. As shown in the side view of FIG. 1, the light guide plate 2 is formed in a substantially wedge shape in a side view in which a front surface 2a that is a light exit surface and a back surface 2b that is a reflection surface are formed non-parallel. The light guide plate 2 is not limited to a wedge shape, and may be a flat plate shape.
In the present embodiment, the optical sheet 3 includes a diffusion plate (PET) 3a, a first lens sheet (PET) 3b, and a second lens sheet (PET) 3c, which are stacked in this order from the bottom. . The lens sheets 3b and 3c can be omitted, and the specific configuration of the optical sheet disposed on the light exit surface 2a of the light guide plate 2 is not particularly limited. The optical sheets 3a, 3b, 3c and the reflecting plate 4 are formed in a rectangular shape (rectangular shape) that is substantially the same shape as the light guide plate 2 in plan view.
[0014]
A linear light source 5 is disposed to face an end surface (introduction surface) 2 c on the thick side of the light guide plate 2, that is, an end surface 2 c on one side of the long sides of the rectangular light guide plate 2. The linear light source 5 is provided along the long side end surface 2c which is an introduction surface, and light is introduced into the light guide plate 2 from the introduction surface 2c.
The linear light source 5 is attached to one side of a frame (not shown) to which the light guide plate 2, the optical sheet 3, and the reflection plate 4 are attached.
FIG. 2 shows how the reflecting plate 4 and the light guide plate 2 are fixed. On the surface of the reflecting plate 4 facing the light guide plate 2, glue printing 6 for fixing to the light guide plate 2 is applied. Yes. The paste printing 6 is a portion corresponding to the non-display area of the backlight 1 and is applied to the adhesion area (shaded portion in FIG. 2) A at the edge of one side 4a of the long sides of the reflector 4. . Also, no glue printing is applied to the other three edges.
[0015]
The adhesive area A to which the paste printing is applied is formed in a strip shape in parallel with the long side 4a with a certain width from the end of the long side 4a. Since glue printing is less likely to peel off than double-sided tape, the width can be reduced compared to double-sided tape, and the space occupied by glue printing can be reduced to accommodate narrower frames. In particular, when the reflector 4 is once pasted and fixed to the light guide plate 2 and then peeled off again, if the double-sided tape is used, the double-sided tape may be peeled off from the reflector 4 or the double-sided tape may be stretched and damaged. However, since glue printing is difficult to peel off from the reflector 4, such a problem is unlikely to occur.
[0016]
If the width of the bonding area A is, for example, 1 mm or less, it can sufficiently cope with the narrowing of the frame. Further, if the width of the bonding area A is about 0.3 mm, further space saving can be achieved. Also, compared to the operation of “pasting” the double-sided tape on the reflector 4, the operation of “printing” the paste on the reflector 4 has better positional accuracy, and the use of glue printing can cause misalignment. Can be prevented. When verified in the present embodiment, the accuracy of paste printing is ± 0.2 mm, and high reliability was obtained. Further, by reducing the width of the paste printing, abnormal light emission in the paste printing can be suppressed.
[0017]
Moreover, since the paste printing 6 of the reflecting plate 4 is provided only on one side and is fixed to the light guide plate 2 only on one side, even if the reflecting plate 4 is extended by applying heat, all the sides are not fixed. The elongation can be absorbed, and the reflection plate can be prevented from bending, wrinkling, and lifting.
FIG. 3 shows the second lens sheet 3c as the uppermost layer among the optical sheets. The lens sheet 3c has a portion corresponding to a non-display area (backlight peripheral portion) of the backlight 1 and is glue-printed on an adhesive area (shaded portion in FIG. 3) B at the edge of the short sides 13a and 13b. 7a, 7b and 7c are applied.
[0018]
In addition, the long side 13c where the linear light source 5 is arranged and the other long side 13d are not subjected to paste printing. Since the long side 13c is close to a linear light source, if the long side 13c is subjected to paste printing, the paste printing may cause abnormal light emission, and the light guide plate 2 corresponding to the long side 13d also on the other long side 13d side. Since there is some reflected light reflected on the side end surface 2d of the long side (opposite surface of the introduction surface 2c), abnormal light emission may occur if paste printing is applied to the long side 13d.
Since the second lens sheet 3c is provided with paste printing 7a, 7b, 7c on both short sides 13a, 13b that are orthogonal to the long side 13c on which the linear light source 5 is disposed, abnormalities due to glue printing Less luminescence.
[0019]
The reflector 4 has paste printing 6 on the long side 4a. If necessary, a shielding member for blocking abnormal light emission is provided on the backlight 1 along the long side 4a. May be.
Further, in the second lens sheet 3c, the short sides 13a, 13b are provided with the paste prints 7a, 7b, 7c. It is possible to prevent the second lens sheet 3c from being displaced in a direction parallel to the.
[0020]
The positional deviation of the second lens sheet in the direction of the short sides 13a and 13b causes a deviation of the reflected light generation position on the side edge 2d of the long side of the light guide plate 2, but the paste printing 7a is applied to the short sides 13a and 13b. , 7b, 7c can prevent this.
Furthermore, in the second lens sheet 3c, paste printing is performed only on the two opposite sides 13a and 13b. Therefore, even if the second lens sheet 3c is stretched by applying heat, the elongation is not performed on the unfixed sides. It can be absorbed, and the optical sheet can be prevented from being bent, wrinkled or lifted.
[0021]
On one short side 13a of the second lens sheet 3c, glue printing 7b, 7c is given in two places, and glue printing 7a, 7b, 7c is given in three places together with the other short side 13b. However, even in a plurality of places as described above, paste printing can be performed at a time.
Ear parts 15a and 15b projecting sideways are formed on both short sides 13a and 13b of the second lens sheet 3c. These ears 15a and 15b are for positioning the second lens sheet 3c on the frame frame.
[0022]
Further, the other optical sheets 3a and 3b are similarly formed with ears, and can be similarly positioned. The diffusion plate 3a and the first lens sheet 3b are not subjected to paste printing, and are engaged with the frame frame 17 by the ears and sandwiched between the second lens sheet 3c as the uppermost layer and the light guide plate 2. It is fixed.
In order to perform paste printing on a film body such as the optical sheet 3 (second lens sheet 3c) or the reflecting plate 4, a printing plate (screen) having a hole in a position corresponding to a portion (bonding area) to be printed on the film body. ) Is used for screen printing.
[0023]
In this case, the glue printing may be performed on all of the bonding areas A and B as shown in FIG. 2 or FIG. 3, but may also be performed partially on the bonding area A as shown in FIG. 4 or FIG. Good. That is, in the adhesive area A, the circular paste print 6 is applied as a dotted pattern. By partially applying the glue printing 6 in the bonding area A, the total area of the glue printing 6 is smaller than the area of the bonding area A, and the adhesive force is smaller than that in which the entire adhesive area A is glued. Become.
Therefore, even when paste printing is performed using the same glue, different adhesive strengths can be obtained depending on the area of the glue print 6. For example, as shown in FIG. 5, the total area of the paste print 6 is reduced by reducing the area of one of the circular paste prints 6 or by reducing the number of the circular paste prints 6 as compared with FIG. Small adhesion can be obtained.
[0024]
In this way, an arbitrary adhesive force can be obtained by changing the pattern of the glue print 6. Note that the shape of each glue print 6 is not limited to a circular shape, but may be an arbitrary shape such as a quadrangle.
In order to perform partial glue printing, it is easy to use the screen having holes corresponding to each of the six glue prints in the range corresponding to the adhesive area A. In order to change the roughness, the roughness of the screen eyes (holes) may be changed in consideration of physical properties such as the viscosity of the glue used.
[0025]
For example, the adhesive strength can be adjusted by preparing a plurality of screens with different eye roughnesses, changing the screen to be used according to the required adhesive strength, and performing paste printing. The screen roughness can be, for example, 50 to 400 mesh.
Partial glue printing (pattern printing) is dispersed in the bonding area A, but can be performed by screen printing once, which is different from the trouble of performing glue printing on the entire bonding area A. It can be done at the same cost. Further, since the partial paste printing is distributed substantially uniformly in the bonding area A, a uniform adhesive force is given to the bonding area.
[0026]
FIGS. 6A and 6B show another embodiment relating to paste pattern printing. In the adhesive area A, in addition to the circular paste prints 6 and 6, the film bodies 3 and 4 can be printed by glue printing. The number 6a as an identification symbol is written.
This number 6a is used to identify the types of the film bodies 3 and 4 by writing numbers such as “1” and “2” on the various film bodies. For example, when only the material is changed, it is difficult for the worker to distinguish on the production line, but it can be distinguished by the number 6a as the identification symbol.
[0027]
Moreover, when using the similar film bodies 3 and 4, film number 3 and 4 can be distinguished by the number 6a as an identification symbol. Thus, management of the film bodies 3 and 4 becomes easy because the identification symbol 6a is described. Further, since the identification symbol 6a can be applied by screen printing at the same time as glue printing for adhesion, a special operation for marking the identification symbol 6a is not required.
In FIG. 6, the circular paste print 6 and the number paste print 6a have different shapes. However, as shown in FIG. 7, a large number of number paste prints 6a are applied in the bonding area A, and each number paste print 6a. It is good also as partial glue printing itself. Further, the identification symbol is not limited to a number, and may be an arbitrary shape such as a circle or a square. Further, by changing the shape of the partial paste print 6 applied in a scattered manner depending on the type of the film body, the partial paste print 6 itself can serve as an identification symbol.
[0028]
Since the paste printing as described above is performed by screen printing using a printing plate having a hole in a portion to be printed, even if the shape of the paste printing target is complicated, there are a plurality of paste printing portions. Even if it exists, it can print at once.
In addition, glue printing has higher positional accuracy as in normal ink printing, and is therefore more reliable than applying double-sided tape.
Furthermore, since the thickness of the glue printing can be made very thin, it is effective for thinning the backlight. For example, the thickness of the paste printing can be reduced to about 10 μm.
[0029]
8 and 9 show another embodiment of the backlight. The backlight 101 includes a light guide plate 102, a lens sheet 103 a and a diffusion sheet 103 b disposed on the light exit surface 102 a side of the light guide plate 102, and a reflector plate 104 disposed on the reflection surface 102 b side of the light guide plate 102. Further, a linear light source (lamp) 105 is provided on one end side of the light guide plate 102.
The light guide plate 102 has a light condensing function in order to achieve thinness, light weight and high luminance, and a prism surface is formed on the reflection surface 102b. The prism surface is formed by providing a plurality of parallel triangular stripes, and the triangular stripes extend in a direction orthogonal to the lamp 105. Note that a lenticular may be formed on the reflecting surface 102 instead of the prism. By forming the prism or lenticular, the light guide plate 102 with high light collection efficiency can be obtained.
[0030]
In addition, the light exit surface 102 a of the light guide plate 102 is textured. Since the lens sheet 103a and the diffusion sheet 103b are overlapped as optical sheets one by one on the light exit surface 102a, the light exit surface 102a is thinner than the backlight using two each.
In the backlight 101 configured as described above, the ridge line of the prism (convex portion) of the light condensing light guide plate 102 is in contact with the reflection plate 104 as shown in FIG. Moreover, abnormal light emission occurs at the contact portion between the light guide plate 102 and the reflection plate 104 due to pressing from the chassis 110 disposed on the lower surface of the reflection plate 104 (the surface opposite to the surface facing the light guide plate 102), and the thickness is thin. Therefore, this abnormal light emission is reflected on the light exit surface of the backlight 101. Accordingly, there is a problem that luminance unevenness occurs on the light exit surface of the backlight 101. Further, there is a problem that the reflection surface 102b of the light guide plate 102 is damaged or dirty when pressed strongly.
[0031]
In order to suppress such pressing of the light guide plate reflecting surface 102b to the reflecting plate 104 by the convex portions (prisms), a concavo-convex portion is formed on the surface of the reflecting plate 104 facing the light guiding plate 102. By forming irregularities on the reflecting plate 104, pressing of the convex portions of the light guide plate 102 to the reflecting plate 104 is suppressed, and uneven brightness and abnormal light emission can be prevented.
The unevenness on the reflector 104 can be formed by hot pressing so as to form an uneven surface on the surface of the foamed PET film to be the reflector 104 (contact surface with the light guide plate 102).
[0032]
Further, a concave / convex surface can be formed on the reflective plate 104 by printing a shrink pattern on the reflective plate 104, and the convex surface of the light guide plate reflective surface 102b can be formed in the same manner as the reflective plate 104 having the concave / convex surface formed by hot pressing. Therefore, it is possible to prevent uneven brightness and abnormal light emission.
The uneven surface by shrinkage pattern printing is formed with a transparent UV shrinkage ink. UV shrinkage ink is an ink in which the surface of a printed film is finished in a shrinkage pattern when cured and dried, and the transparent shrinkage pattern forms irregularities.
[0033]
As the shrink ink, for example, a TJN series (particularly, TJN Medium A) manufactured by Seiko Advance Co., Ltd. can be used. Further, a slightly diffusing agent (such as beads) may be mixed in the shrink ink.
In order to manufacture the reflective plate 104 with a shrink pattern, first, a predetermined PET (light absorption part and bright line prevention band) is printed on the foamed PET film to be the reflective plate 104 according to the use of the backlight. This printing can be omitted if unnecessary.
Next, an anchor coat is applied as a pretreatment to the surface of the reflecting plate 104 that comes into contact with the light guide plate 102, and then the UV shrinking ink is solid-printed or pattern-printed as necessary. The printing area may be the entire reflection plate 104 or a partial area as required. Screen printing can be used as the UV shrink ink printing, and the screen mesh can be 60 to 270.
[0034]
Immediately after printing the UV shrink ink, it is dried in a shrink apparatus and UV curing apparatus. At this time, the printed material is fed at a speed of 3 m / min.
Thereafter, the printed material is cut into a predetermined size, and the reflection plate 104 is obtained. It should be noted that this step can be omitted naturally when there is no need to cut the film body during printing, such as the size of the reflector 104.
The unevenness formation of the reflector 104 by the UV shrink ink has the following advantages compared to the unevenness formation by hot pressing.
[0035]
First, the uneven surface formed by hot pressing tends to return to the original flat shape when heated, and the unevenness is reduced or eliminated. For example, when the reflector 104 is heated at 90 ° C. for 1 hour, the unevenness is considerably eliminated. On the other hand, in the reflector 104 in which the shrinkage pattern is formed, the unevenness is not lost by heat.
Further, in the hot press process, when the unevenness is applied, the reflector is stretched by less than about 3%. Therefore, when the unevenness is eliminated by heat, the stretched portion contracts. On the other hand, the size of the reflector 104 on which the shrinkage pattern is formed does not change due to heat. When heat was applied at 90 ° C. for 5 hours to the shrunk pattern of the reflector 104, the dimensional change was less than 0.05.
[0036]
When the dimensional change of the reflector 104 occurs, the light absorbing part for improving the light emission quality of the pack light and the light absorbing band for preventing the bright line are misaligned, and those effects cannot be obtained. Such a problem is less with the reflector 104.
Moreover, since the unevenness | corrugation by shrinkage | contraction pattern printing is transparent, the function as the reflecting plate 104 is securable. When the reflectivity is reduced to 90% or less by shrinkage pattern printing, the reflection plate 104 becomes considerably dark. However, since the shrinkage pattern printing is transparent, a decrease in reflectivity can be prevented compared to an opaque one.
[0037]
Further, since the printed pattern is transparent, it is possible to prevent the printed part such as the light absorption part and the bright line prevention band printed on the reflection plate from being obstructed by the printed shrinkage pattern.
[0038]
【The invention's effect】
According to the present invention, since the glue printing is partially performed for adjusting the adhesive force in the adhesive area, different adhesive forces can be realized even if the same adhesive is used.
Moreover, uniform adhesive force can be obtained in the bonding area by applying the paste printing in the form of scattered dots having a substantially uniform distribution in the bonding area.
Furthermore, since the identification symbol for identifying the type of the film body is written by glue printing, it is easy to distinguish various types of film bodies on a production line or the like.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a backlight. FIG. 2 is a perspective view showing how to attach a light guide plate and a reflection plate.
FIG. 3 is a plan view of an optical sheet.
FIG. 4 is a plan view of a reflector plate in which partial paste printing is performed on an adhesive area.
FIG. 5 is a plan view of a reflector plate in which partial glue printing having a smaller area than that in FIG.
FIG. 6 is a partial plan view of a reflecting plate in which a number as an identification symbol is applied to an adhesive area by glue printing.
FIG. 7 is a partial plan view of a reflector plate that has been subjected to partial glue printing that also serves as an identification symbol in an adhesive area.
FIG. 8 is a perspective view of a backlight according to another embodiment.
FIG. 9 is a side structure of a light guide plate, a reflection plate, and a chassis of a backlight according to another embodiment.
FIG. 10 is a plan view showing a non-display area of a conventional backlight.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Backlight 2 Light-guide plate 3 Optical sheet 4 Reflecting plate 5 Linear light source 6 Paste printing 6a Identification symbol A Adhesive area B Adhesive area

Claims (7)

A backlighting film body paste printing is performed for the pasting,
The glue printing is partially applied for adjusting the adhesive force within the adhesive area where the glue printing is performed ,
The film body for a backlight according to claim 1, wherein the paste printing is applied in the form of dots having a substantially uniform distribution in the bonding area .   The film body for a backlight according to claim 1, wherein the adhesive area is a portion corresponding to a non-display area at a peripheral edge portion of the backlight. Backlight film body according to claim 1 or 2 identification mark for identifying the type of the film body, characterized in that marked by the glue printing. Before SL backlight film body is a reflective plate attached to the reflection surface side of the light guide plate,
The film body for a backlight according to any one of claims 1 to 3, wherein unevenness is formed by shrinkage pattern printing on a contact surface of the reflection plate with the light guide plate. 5. The backlight film body according to claim 4 , wherein the contact surface of the reflection plate with the light guide plate is formed with irregularities by printing a transparent shrinkage pattern. A method for producing a film body for backlight to which paste printing for application is applied,
When performing glue printing on the adhesive area on which the glue printing of the film body is performed, an adhesive area having a desired adhesive force is formed by varying the area of the glue printing with respect to the entire area of the adhesive area ,
A method for producing a film body for a backlight, characterized in that the paste printing is performed in the form of scattered dots having a substantially uniform distribution in an adhesive area . 7. The method of manufacturing a backlight film body according to claim 6 , wherein an identification symbol for identifying a type of the film body is simultaneously applied to the film body by the glue printing when the paste printing is performed.

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