JP2010120353A - Method for welding sheet object, and method for manufacturing optical sheet laminate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for welding sheet object for effectively utilizing sheet objects by preventing the molten sheet objects from undesirably expanding to the outside in a face direction when a plurality of the sheet objects are superposed one upon another to be welded to each other, and a method for manufacturing an optical sheet laminate using the same. <P>SOLUTION: A space 7 is formed to a laminate 20 between the sheet object 5 of the uppermost layer being the sheet object of the outermost layer and the sheet object 1 of the lowermost layer over a predetermined melting region 11 where the sheet objects are melted and an expansion region expanded to the outside in the face direction from the melting region 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for welding a sheet body that presses and welds three or more sheets laminated in the thickness direction, and a method for producing an optical sheet laminate using the sheet body. The present invention relates to a method for welding ultrasonically welded sheets and a method for producing an optical sheet laminate using the same.

  Liquid crystal displays are used in mobile phones, notebook computers, liquid crystal televisions, and the like. A backlight is necessary for a transmissive liquid crystal display, and in order to improve display performance, a plurality of optical sheets for adjusting the light emitted from the backlight are stacked on the backlight unit including the backlight. Built in. Examples of the optical sheet that is a sheet body include a light diffusion sheet that diffuses light emitted from a backlight, and a prism sheet that has a plurality of lenses arranged adjacent to each other and controls the traveling direction of light passing through the sheet. Can be mentioned.

  Conventionally, when manufacturing a backlight unit, the optical sheets are punched one by one into a predetermined shape, and the optical sheets after such punching are sequentially stacked in the frame of the backlight unit by hand. .

  Recently, demands for cost reduction as a response to the price reduction of liquid crystal displays have become stricter, and demands for cost reduction have also increased in the manufacturing process of backlight units.

  As a method for meeting such demands, optical sheets such as a diffusion sheet and a prism sheet that have been punched into a predetermined shape one by one in the past are laminated in a required configuration in advance, and a plurality of laminated optical There is a method in which a sheet is welded and punched into a necessary shape in a laminated state. For example, Patent Documents 1 and 2 disclose a method of welding a plurality of sheet bodies.

JP 2007-76069 A JP 2001-158047 A

  A case where a plurality of optical sheets are welded using the method disclosed in Patent Document 1 will be described with reference to FIGS.

  FIG. 6 is a diagram for explaining the state of the laminated body 100 before and after the sheet body is welded. Fig.6 (a) is sectional drawing which shows the laminated body 100 before a sheet | seat body is welded. The laminated body 100 is configured by laminating five sheet bodies 101, 102, 103, 104, and 105 in the thickness direction. 6B is an enlarged plan view showing a part of the laminated body 100 after the sheet body is welded, and FIG. 6C is a cross-sectional line III- shown in FIG. It is sectional drawing in III. FIG. 7 is a plan view showing the laminated body 100 after the sheet body is welded.

  As shown in FIG. 6A, the laminated body 100 is configured by the sheet bodies 101 to 105 having a substantially uniform thickness in the surface direction, and the laminated body 100 is placed on the welding stage 106. The laminated body 100 is welded while being pressed from above by the welding member 108 in such a state.

  At this time, a part of the melted sheet body loses a place to go, and for example, the sheet body is melted in a plan view while spreading between the sheet body 102 and the sheet body 103 as shown in FIG. It spreads outward from the melting region 111, which is a region that flows, and flows out. Hereinafter, an area where the melted sheet body flows out of the melting area 111 in a plan view is referred to as an outflow area 112. That is, a part of the molten sheet body is re-solidified in the melting region 111 to form the re-solidified portion 109 to join each sheet body, while the remaining molten sheet body is re-solidified in the outflow region 112. Thus, the resolidification part 110 is formed.

  In this way, a part of the melted sheet body flows out of the melted region 111 while spreading between the sheets until it is resolidified, so that the outflow region 112 is undesirably enlarged. There is.

  Further, when the laminated body 100 on which the sheet body is welded is punched into a desired shape, if it is necessary to punch out so that the outflow region 112 is not included in the punching region, the outflow region 112 is formed as described above. There is a problem that the material cannot be effectively used due to the increase in size.

  Further, when the melted sheet body flows out by spreading between the sheets, it does not necessarily spread uniformly along the surface direction. Therefore, when the welding process and the punching process are automated, the outflow area 112 is included in the punching area. Therefore, there is a problem in that it is necessary to perform punching at a position far away from the melting region 111 more than necessary, and the portion where the material cannot be effectively used further increases, which is uneconomical.

  Patent Document 2 discloses a method of joining two plastic films by ultrasonic fusion. Specifically, two plastic films were placed on a horizontal base so that the distance between the terminal portions of each film was a predetermined distance, and the plastic film was further stacked to cover both terminal portions. In this state, a method of welding while pressing with an ultrasonic generation horn is disclosed. According to this method, since the diameter of the circular flat portion at the tip of the welding horn is very large compared to the distance between the two plastic films, when a plurality of plastic films are stacked and welded, Since the volume of the member to be increased increases, there is also a problem that the outflow region becomes undesirably large.

  The present invention has been made in view of the above-mentioned problems, and prevents the molten sheet body from undesirably spreading outward when a plurality of sheet bodies are stacked and welded, and the sheet material is effectively used. It is an object of the present invention to provide a method for welding a sheet body that can be used for the present invention and a method for producing an optical sheet laminate using the same.

In the present invention, a sheet body is laminated in a thickness direction of three or more layers to form a laminated body, and the sheet body is melted while pressing the laminated body in the thickness direction by a welding member to weld the sheet body. A sheet body welding method,
The laminated body includes a predetermined melting region in which the sheet body is melted between one outermost layer and the other outermost layer arranged on the outermost side in the thickness direction, and outward in the plane direction from the melting region. The sheet body welding method is characterized in that a space is formed over an extended region extending in a wide area.

  In the invention, it is preferable that the space is formed by forming a notch in the sheet body of at least one or more intermediate layers.

  Further, the present invention is characterized in that the notch is formed in a rectangular shape when viewed in the thickness direction of the laminate.

  In the invention, it is preferable that the space is formed by disposing a plurality of sheet members formed in a strip shape in a plane direction apart from each other in at least one intermediate layer.

Further, the present invention is a method for welding the sheet body,
The welding member is an ultrasonic welding horn, and the sheet body is melted and welded by frictional heat generated between the ultrasonic welding horn and the laminate by applying vibration to the ultrasonic welding horn. This is a method for welding the sheet body.

  In the invention, it is preferable that the laminate includes an optical sheet incorporated in a backlight unit.

Further, the present invention is a welding step of welding the sheet body of each layer by the sheet body welding method,
A laminate after welding, a punching step of punching into a predetermined shape in the thickness direction to form an optical sheet laminate, and a method for producing an optical sheet laminate,
A method for producing an optical sheet laminate, wherein the laminate after welding is punched into a predetermined shape outside the welded region.

  According to the present invention, between each sheet body constituting one outermost layer and the other outermost layer of the laminate, a predetermined melting region in which the sheet body is melted and outward in the plane direction from the melting region. Since the space is formed over the extended region that has spread, when the sheet body is melted while pressing the laminated body in the thickness direction by the welding member, a part of the melted sheet body can flow into the space. it can. Therefore, the melted sheet body can be prevented from undesirably spreading outward in the plane direction, and the material constituting the laminate can be used effectively.

  Below, with reference to drawings, the welding method of the sheet body which concerns on embodiment of this invention is demonstrated in detail.

  FIG. 1 is a cross-sectional view showing step by step a process of welding a plurality of sheet bodies by the sheet body welding method according to the present embodiment. FIG. 2 is an enlarged plan view showing a part of the laminate 20 shown in FIG. The laminated body 20 shown in FIG. 1 has shown the cross section of the laminated body 20 cut | disconnected by the cutting surface line II shown in FIG.

  Fig.1 (a) has shown the state before the several laminated | stacked sheet | seat body is welded. In the following, as shown in the figure, a description will be given of a case where the sheet body is implemented in a laminated body 20 (hereinafter, sometimes referred to as “laminated body having a five-layer structure”) 20 configured to be stacked in five layers. However, the sheet body welding method according to the present embodiment is not limited to the case of five layers, and can be suitably implemented in a laminated body configured by stacking three or more layers. In the laminate 20, it is assumed that one sheet body constitutes one layer.

  In the following description, when the laminated body 20 having a five-layer structure is described, the first layer sheet body 1, the second layer sheet body 2, the third layer sheet body 3, It is assumed that the four-layer sheet body 4 and the fifth-layer sheet body 5 are stacked. Accordingly, the first layer sheet body 1 corresponds to the lowermost sheet body, the fifth layer sheet body 5 corresponds to the uppermost sheet body, and the first layer and the fifth layer sheet bodies 1 and 5 are the outermost layers. It corresponds to each sheet body constituting. Further, the sheet body existing between the first layer sheet body 1 and the fifth layer sheet body 5, that is, the second layer, the third layer, and the fourth layer sheet bodies 2, 3 and 4 are intermediate sheet layers. It corresponds to. The laminate 20 in the present embodiment will be described in detail later.

  The laminate 20 is subjected to a welding process in, for example, an ultrasonic bonding apparatus. The ultrasonic bonding apparatus includes a stage 6 and an ultrasonic welding horn (hereinafter referred to as “horn”) 8. The stage 6 has a horizontal placement surface 6a on which the stacked body 20 is placed. In a state where the stacked body is placed on the placement surface 6a, the placement surface 6a and the first layer sheet body 1 are in contact with each other.

  The horn 8 is a substantially right cylindrical member, and has a substantially hemispherical curved surface 8a that is curved outwardly at one end. In the present embodiment, a horn 8 having one end side formed in a substantially hemispherical shape is used. However, in another embodiment, a horn having a flat surface at the end on one end side is used. There may be.

  The horn 8 is arranged so that the central axis of the horn 8 is perpendicular to the placement surface 6 a and the curved surface 8 a faces the stage 6. That is, the laminate 20 is interposed between the curved surface 8 a of the horn 8 and the mounting surface 6 a of the stage 6.

  An unillustrated ultrasonic transmission source is connected to the horn 8, and the horn 8 is configured to ultrasonically vibrate at a predetermined frequency in a predetermined direction by operating the ultrasonic transmission source. In the present embodiment, the horn 8 is configured to vibrate in the vertical direction in FIG.

  Further, the horn 8 is configured to be driven in a vertical direction in FIG. 1, that is, in a direction approaching and separating from the stacked body 20 mounted on the stage 6 by a moving mechanism such as an actuator (not shown).

  With such a configuration, the ultrasonic bonding apparatus drives the horn 8 vertically downward and ultrasonically vibrates the horn 8 in the vertical direction in a state where the laminated body 20 is pressed. Frictional heat can be generated between 8a and the laminate 20, and the sheet can be melted. And the sheet | seat bodies can be welded by resolidifying the fuse | melted sheet | seat body.

  The laminated body 20 used in the present embodiment will be described in detail. The remaining sheet bodies 1, 2, 4, 5 excluding the third layer sheet body 3 have a substantially uniform thickness along the surface direction. On the other hand, the third layer sheet body 3 is formed with a notch 3a having a predetermined size.

  The notch 3a is formed to extend with substantially the same width d1 in the direction perpendicular to the paper surface in FIG. Thus, since the notch 3a is provided in the 3rd layer sheet body 3, the 1st layer sheet body 1 and the 5th layer are formed in the laminated body 20 formed by stacking the sheet bodies 1-5. A space 7 is formed between the sheet body 5 and the sheet body 5.

  As shown in FIG. 1A, the stacked body 20 before being welded is placed on the stage 6 so that a horn 8 described later is disposed above the space 7 formed in the stacked body 20. More specifically, the stacked body 20 is arranged so that the central axis of the horn 8 is positioned at the approximate center in the width direction of the space 7.

  FIG. 1B shows a state in which the laminate 20 is pushed in the thickness direction by the horn 8. The horn 8 is driven vertically downward from above until a predetermined pressing force is applied to the stacked body 20. And when the predetermined pressing force is given with respect to the laminated body 20, the horn 8 is ultrasonically vibrated by operating an ultrasonic transmission source. At this time, the frictional heat is generated between the curved surface 8a of the horn 8 and the laminated body 20, whereby the sheet body is melted.

  FIG.1 (c) has shown the state immediately after the sheet | seat body fuse | melted. As described above, the horn 8 is ultrasonically vibrated in a state where a predetermined pressing force is applied to the laminated body 20 to obtain a predetermined depth (that is, a distance in the thickness direction from the upper surface of the uppermost sheet body). The sheet body up to is melted. After the horn 8 is ultrasonically vibrated for a predetermined time, the ultrasonic transmission source is stopped. Thereby, when the ultrasonic vibration of the horn 8 is stopped, the molten sheet body is cooled and re-solidified. Since the sheet body is melted in such a state that the front end portion of the horn 8 is pushed into the laminated body 20, the molten sheet body that has lost its destination is in the space 7 previously formed in the laminated body 20. Flows in. That is, a part of the melted sheet body 9 is re-solidified in the concave portion formed by melting the sheet body and welds each sheet body, whereas the remaining melted sheet body 10 It flows into the space 7 formed in the three-layer sheet body 3 and re-solidifies.

  In the present embodiment, as described above, the horn 8 is used as a welding member, and the horn 8 is ultrasonically vibrated to melt the sheet body by frictional heat generated between the horn 8 and the sheet body. ing. The frictional heat at this time is generated in the vicinity of the interface between the horn 8 and the sheet body, and further, the ultrasonic vibration is stopped before the heat is transmitted to the inside of the horn 8, so that it melted in a very short time. The sheet body is cooled. Therefore, even when the material of the sheet body is a synthetic resin, it is possible to prevent the molten sheet body from adhering to the horn 8 and re-solidifying. In other embodiments, the welding member may itself be configured to generate heat.

  FIG. 3 is a diagram for explaining the state of the laminated body 20 before and after the sheet body is welded. Fig.3 (a) is sectional drawing which shows the laminated body 20 before a sheet | seat body is welded. FIG. 3B is a plan view showing the laminated body 20 after the sheet body is welded, and FIG. 3C is a cross-sectional view taken along the section line II-II shown in FIG. .

  Here, the notch 3a formed in the 3rd layer sheet body 3 is demonstrated. The size of the notch 3a is determined based on a predetermined melting region where the sheet body is melted. Here, the predetermined melting region is a region shown when a portion of the laminate 20 where the sheet member is melted is projected onto a plane perpendicular to the thickness direction of the laminate 20, and FIG. It corresponds to a region indicated by a region 11 (hereinafter referred to as “melted region 11”) in b). The melting region 11 of the sheet body is determined in advance based on the shape of the tip of the horn 8 used for melting the sheet body. In the present embodiment, as described above, since one end portion side of the horn 8 is formed in a substantially hemispherical shape, the melting region 11 is circular.

  The notch 3a is formed so as to form a space 7 penetrating in the thickness direction over the melted region 11 and an extended region spreading outward in the plane direction from the melted region 11 on the one plane. . At this time, the size of the extended region is determined in advance based on the volume of the sheet member melted by the horn 8. Here, the diameter of the melting region 11 having a circular shape is defined as d2. The notch 3a is formed so as to form a space extending in the plane direction over the predetermined melting region and the expansion region, that is, formed so as to be larger than the melting region 11, and as shown in FIG. However, it is formed by d1> d2).

  The width d1 has the same configuration as that of the laminate 20 in the present embodiment and is pressed by the horn 8 against the laminate when the space 7 is not formed in the third layer sheet 3. When the sheet body is welded by ultrasonically oscillating the horn 8, the maximum width of the outer shell defining the region where the melted sheet body spreads outward from the melted area in the plane direction and resolidifies (width in FIG. 6). It may be smaller than D1).

  As described above, a part of the molten sheet body 10 flows into the space 7 formed in the third layer sheet body 3 and spreads. At this time, when the melted sheet body 10 reaches the end surface of the notch 3a of the third layer sheet body 3 that defines the space 7, the molten sheet body 10 flows along the end surface. That is, by providing the notch 3a, not only a space into which the melted sheet body 10 flows is formed, but the spread of the melted sheet body 10 can be prevented by the end face of the notch 3a. That is, it is possible to prevent the melted sheet body 10 from flowing out to the region where the five sheet bodies are laminated.

  In the present embodiment, since the notch 3a is formed in a rectangular shape extending in the width d1 when viewed in the thickness direction of the laminate, the molten sheet body 10 is moved outwardly in the plane direction from the space 7, in particular. Spreading in the direction of the width d1 can be effectively prevented, that is, it is possible to prevent a region where the melted sheet body 10 is spread from becoming larger than the width d1. In this way, in the laminate 20, by providing a space of a predetermined size in the intermediate layer in advance, it is possible to limit a region where the melted sheet body 10 spreads, and thus the quality is lowered by the melted sheet body 10. This can reduce as much as possible. In other words, the effective area where quality is maintained in the laminate 20 can be made as wide as possible. That is, the material can be used effectively.

  FIG. 4 is a plan view showing the laminated body 20 after the sheet body is welded. FIG. 4A shows the laminate 20 when the space 7 is formed by the notch 3a shown in FIG. FIG. 4B shows the laminate 20 in the case where the space 7 is formed by configuring the third layer sheet body 3 with a plurality of strip-shaped sheet members 31.

  The laminated body 20 in FIG. 4A is formed by sequentially laminating the sheet bodies drawn from the original fabric rolls corresponding to the respective sheet bodies 1 to 5, and further, the notch in the third layer sheet body 3. For example, 3a is formed by a cutting means (not shown) immediately before the sheet bodies are laminated. In the third layer sheet body 3, the notches 3a are provided at equal intervals with a predetermined interval in the left-right direction of FIG. The laminated body 20 formed in this way is pulled out to the ultrasonic bonding apparatus, and is arranged so that the space 7 is positioned vertically below the horn 8 as described above. Then, as described above, the welding process is performed by the ultrasonic bonding apparatus.

  Moreover, the laminated body 20 of FIG.4 (b) is the sheet | seat body 31 each pulled out from the original fabric roll corresponding to each sheet | seat body 1,2,4,5, and the sheet | seat member 31 previously cut | disconnected by the rectangular strip shape. Are sequentially laminated. The sheet member 31 is disposed between the second layer sheet body 2 and the fourth layer sheet body 4 so as to be separated from each other by a predetermined distance d1. In this way, in the laminated body 20, the sheet members 31 are arranged in the plane direction so as to be spaced apart from each other by the distance d <b> 1, thereby forming the third layer sheet body 3, thereby penetrating the sheet members 31 in the thickness direction. A space 7 is formed. The laminated body 20 formed in this way is pulled out to the ultrasonic bonding apparatus, and is arranged so that the space 7 is positioned vertically below the horn 8 as described above. Then, as described above, the welding process is performed by the ultrasonic bonding apparatus.

  4 (a) and 4 (b), the laminated body 20 is configured so as to form the space 7 only in the third layer sheet body 3. However, in the two or more intermediate layer sheet bodies, It may be configured to form a space.

  Hereinafter, the configuration of the laminate 20 used in the present embodiment and the specifications of the ultrasonic bonding apparatus will be described with a specific example. In the laminate 20, the first layer sheet body 1 is a blade contact sheet having a thickness of 75 μm, the second layer sheet body 2 is a diffusion sheet having a thickness of 50 μm, and the third layer sheet body 3 has a thickness. The prism sheet is 70 μm, the fourth layer sheet body 4 is a prism sheet having a thickness of 70 μm, and the fifth layer sheet body 5 is a diffusion sheet having a thickness of 50 μm. Thus, the laminated body 20 is configured to include optical sheets such as a diffusion sheet and a prism sheet. The diffusion sheet and the prism sheet are obtained by forming a diffusion layer and a prism on the surface of a base film made of polyethylene terephthalate (PET) having a melting point of about 260 degrees, respectively.

  Here, the blade contact sheet is a sheet for preventing the blade from directly hitting the stage on which the laminate 20 is mounted in a punching process described later. The blade contact sheet is also formed using polyethylene terephthalate (PET) as a material.

  The used horn 8 has a hemispherical shape with a tip having a diameter of 3 mmφ, and the ultrasonic bonding device causes the horn 8 to oscillate at a time when a pressing force of 4 to 6 kgf is applied to the laminate 20. Control is performed so that the ultrasonic vibration is performed at 28 kHz for 0.1 second. Further, the notch 3a in the third layer sheet body 3 is formed so that the width d1 is 2.0 mm. When implemented under such conditions, as described above, the melted sheet body 10 that has flowed out of the melting region 11 spreads inside the space 7, that is, in the width direction of the notch 3a, it is out of the plane direction beyond the width d1. It was confirmed that it did not spread.

  As a comparative example, when notch 3a is not formed, that is, under the same conditions as described above except that notch 3a is not formed (however, the pressing force applied to the laminate is 7 to 9 kgf) In this case, the maximum width D1 of the outline defining the region where the melted sheet body spreads outward in the plane direction and resolidifies was 3.2 mm.

  In this way, by forming a space in the laminated body in advance, the area where the melted sheet body spreads outward in the surface direction can be made as narrow as possible. Spreading outward in the direction is prevented, and the sheet material can be used effectively.

  In the present embodiment described above, the laminate 20 has a five-layer structure, but it is naturally preferable also in a laminate having a four-layer structure by removing the diffusion sheet corresponding to the fifth layer sheet 5. Can be implemented.

  Hereinafter, the manufacturing method of the optical sheet laminated body which concerns on the other form of implementation of this invention is demonstrated. In the manufacturing method of the optical sheet laminate according to the present embodiment, the laminate 20 welded by the sheet welding method according to the above-described embodiment is used. FIG. 5 is a perspective view showing a process of manufacturing the optical sheet laminate 21 from the laminate 20 after the sheet as shown in FIG. 4B is welded. The laminated body 20 that has been subjected to the welding process as described above is pulled out by driving a drawing means (not shown), and is conveyed in the A1 direction, and then is changed in direction by about 90 degrees by the guide portion 23, so that A2 Conveyed in the direction.

  Since each sheet body is welded as described above in the laminated body 20, a plurality of laminated sheet bodies can be handled integrally. Since each sheet body is pulled out from the raw roll under tension control, the laminated body 20 becomes easy to handle by welding each sheet body, and the configuration of the manufacturing apparatus for manufacturing the optical sheet laminated body is simplified. be able to.

  When the predetermined punching area in the stacked body 20 is transported to the lower side of the punching device 24, the driving of the drawing means is stopped. When the predetermined punching area is arranged below the punching means 24, the optical sheet laminate 21 having a predetermined shape (rectangular shape in FIG. 5) is manufactured by punching by the punching means 24.

  Here, the predetermined punching region is a region outside the welding region in the laminated body 20 after welding, and in detail, between the spaces 7 provided at equal intervals in the longitudinal direction in the laminated body 20. It is the area that is sandwiched. That is, based on a predetermined shape and dimensions when punched, an interval at which the space 7 is provided, in this case, a longitudinal dimension of the sheet member 31 formed in a rectangular strip shape is determined.

  As described above, by restricting the molten sheet body from spreading outward in the surface direction by forming the space 7 in the laminate 20, based on the predetermined shape and dimensions when punched, The interval at which the space 7 is formed, that is, the longitudinal dimension of the sheet member 31 can be determined so as not to cause a useless portion as much as possible. Therefore, the material can be used effectively.

  The punching process will be described in detail. A punching blade having a predetermined shape (not shown) is lowered from the upper side to the lower side of the stacked body 20 mounted on a stage (not shown) below the punching means 24 by the driving means. At this time, the punching blade reaches the blade contact sheet which is the lowermost sheet body 1 and is lowered to a position where it does not hit the stage. Accordingly, the second layer, the third layer, the fourth layer, and the fifth layer sheet bodies 2, 3, 4, and 5 are punched into a predetermined shape, and the optical sheet laminate 21 is manufactured.

  The punched optical sheet laminate 21 is conveyed at an angle in the guide 23 as described above, so that the laminated laminate 20 is not conveyed following the direction-changing laminate 20 in the A1 direction. Be transported. Thus, the optical sheet laminated body 21 extracted from the laminated body 20 is sandwiched by the hand 22 and conveyed to a predetermined position by a conveying means (not shown).

  In the present embodiment, the optical sheet laminate 21 is conveyed to a predetermined position in the backlight unit. As described above, since a plurality of optical sheets previously laminated in a necessary configuration can be punched into a necessary shape while being laminated and incorporated into the backlight unit, the cost can be reduced in the manufacture of the backlight unit.

It is sectional drawing which shows in steps the process in which a some sheet body is welded with the welding method of the sheet body which concerns on this Embodiment. Fig.1 (a) has shown the state before the several laminated | stacked sheet | seat body is welded. FIG. 1B shows a state in which the laminate 20 is pushed in the thickness direction by the horn 8. FIG.1 (c) has shown the state immediately after the sheet | seat body fuse | melted. It is a top view which expands and shows a part of laminated body 20 shown by FIG. It is a figure for demonstrating the state of the laminated body 20 before a sheet | seat body is welded and after being welded. Fig.3 (a) is sectional drawing which shows the laminated body 20 before a sheet | seat body is welded. FIG. 3B is a plan view showing the laminated body 20 after the sheet body is welded, and FIG. 3C is a cross-sectional view taken along the section line II-II shown in FIG. . It is a top view which shows the laminated body 20 after the sheet | seat body was welded. FIG. 4A shows the laminate 20 when the space 7 is formed by the notch 3a shown in FIG. FIG. 4B shows the laminate 20 in the case where the space 7 is formed by configuring the third layer sheet body 3 with a plurality of strip-shaped sheet members 31. It is a perspective view which shows the process of manufacturing the optical sheet laminated body 21 from the laminated body 20 after the sheet | seat body shown in FIG.4 (b) was welded. It is a figure for demonstrating the state of the laminated body 100 before a sheet | seat body is welded and after being welded. Fig.6 (a) is sectional drawing which shows the laminated body 100 before a sheet | seat body is welded. 6B is an enlarged plan view showing a part of the laminated body 100 after the sheet body is welded, and FIG. 6C is a cross-sectional line III- shown in FIG. It is sectional drawing in III. It is a top view which shows the laminated body 100 after a sheet | seat body was welded.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st layer sheet body 2 2nd layer sheet body 3 3rd layer sheet body 3a Notch 4 4th layer sheet body 5 5th layer sheet body 6 Stage 7 Space 8 Ultrasonic welding horn 8a Curved surface 11 Melting area 20 Lamination Body 31 Sheet member

Claims (7)

Sheet body is formed by stacking sheet bodies in the thickness direction in three or more layers to form a laminated body, melting the sheet body while pressing the laminated body in the thickness direction with a welding member, and welding the sheet body A method,
The laminated body includes a predetermined melting region in which the sheet body is melted between one outermost layer and the other outermost layer arranged on the outermost side in the thickness direction, and outward in the plane direction from the melting region. A method for welding a sheet body, characterized in that a space is formed over an extended area extending into the sheet.   The method for welding a sheet body according to claim 1, wherein the space is formed by forming a notch in the sheet body of at least one or more intermediate layers.   3. The sheet body welding method according to claim 2, wherein the notch is formed in a rectangular shape when viewed in the thickness direction of the laminate.   2. The sheet body according to claim 1, wherein the space is formed by disposing a plurality of sheet members formed in a strip shape in a plane direction apart from each other in at least one intermediate layer. Welding method. It is a welding method of the sheet object according to any one of claims 1 to 4,
The welding member is an ultrasonic welding horn, and the sheet body is melted and welded by frictional heat generated between the ultrasonic welding horn and the laminate by applying vibration to the ultrasonic welding horn. The sheet body welding method.   The method for welding a sheet body according to any one of claims 1 to 5, wherein the laminated body includes an optical sheet incorporated in a backlight unit. A welding step of welding the sheet body of each layer by the sheet body welding method according to claim 6;
A laminate after welding, a punching step of punching into a predetermined shape in the thickness direction to form an optical sheet laminate, and a method for producing an optical sheet laminate,
A method for producing an optical sheet laminate, wherein the laminate after welding is punched into a predetermined shape outside the welded region.

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