JP4533400B2 - LCD module unit - Google Patents

Description

  The present invention relates to a liquid crystal display module unit.

  In recent years, liquid crystal display devices are often used as display devices for electronic devices such as mobile phones and electronic notebooks. As a liquid crystal display device used in such a small electronic device, a sidelight type backlight type liquid crystal display device is employed.

  The above-mentioned sidelight type backlight type liquid crystal display device is generally arranged in a synthetic resin backlight casing after optical films such as a reflection sheet, a light guide plate, a diffusion sheet, and a prism sheet are laminated. A liquid crystal display panel is laminated and integrated on the laminated optical film via a double-sided adhesive tape, and a lamp reflector is provided on the side of the light guide plate to provide a light source such as an LED (Light Emitting Diode). Is arranged.

  As the double-sided pressure-sensitive adhesive tape, in Patent Document 1, in a pressure-sensitive adhesive tape having a base material and an adhesive layer on at least one side of the base material, the base material is colored in the order of white, white and black, and black. A pressure-sensitive adhesive tape characterized by having a layer that is formed is described.

  In recent years, there has been a demand for smaller and lighter liquid crystal display devices in order to further reduce the size and weight of electronic devices. To meet this demand, the thickness of the frame of the backlight housing is reduced, or Although the film thickness is being reduced, the backlight casing itself is easily deformed by reducing the thickness of the backlight casing.

  The deformation of the backlight casing is transmitted to the optical film through the double-sided adhesive tape, and the optical film is thinned, so that the optical film is easily distorted and deformed. As a result, the liquid crystal There has been a problem that the display screen is dark and light.

JP 2004-59723 A

  The present invention provides a liquid crystal display module unit having a high-quality liquid crystal display screen without causing wrinkles or distortion of the optical film due to deformation of the backlight casing.

  In the liquid crystal display module unit of the present invention, a panel disposition step is formed on the inner peripheral surface of the frame-shaped backlight casing, and the liquid crystal display panel is disposed on the panel disposition step. A plurality of optical films are disposed in a laminated state in the backlight casing, and the liquid crystal display panel and the optical film facing the liquid crystal display panel are disposed on the panel disposition step. The double-sided pressure-sensitive adhesive tape has an adhesive layer laminated and integrated on both sides of the substrate, and the cohesive force of the adhesive layer facing the optical film faces the liquid crystal display panel. It is comprised so that it may become lower than the cohesion force of the adhesion layer to do.

  In the liquid crystal display module unit, the double-sided adhesive tape is formed in a frame shape.

  Furthermore, in the liquid crystal display module unit, the optical film facing the liquid crystal display panel is a prism sheet.

  In the liquid crystal display module unit, the cohesive force of the adhesive layer is adjusted by adjusting the degree of crosslinking of the adhesive constituting the adhesive layer.

  Since the liquid crystal display module unit of the present invention has the above-described configuration, the adhesive layer of the double-sided adhesive tape smoothly absorbs the deformation stress accompanying the deformation of the backlight housing, and the deformation stress is transmitted to the optical film. Accordingly, the liquid crystal display screen is not uneven due to wrinkles or distortion of the optical film, and a high quality liquid crystal display screen is provided.

  An example of the liquid crystal display module unit of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the backlight housing 1 of the liquid crystal display module unit A is formed in a rectangular frame shape made of synthetic resin, and a planar rectangle for placing a liquid crystal display panel on the upper end. A frame-shaped panel disposing step 11 is formed in an open state at the upper end surface of the backlight housing 1, and a reflecting plate disposing step 12 for disposing a reflecting plate at the lower end. Is formed in a planar rectangular frame shape in a state of opening at the upper end surface.

  A flat rectangular liquid crystal display panel 5 having a size slightly smaller than the upper end opening of the backlight housing 1 is disposed on the panel placement step 11 of the backlight housing 1. In addition, a plurality of optical films are disposed in the backlight housing 1 in a stacked state.

  Specifically, the light guide plate 2, the diffusion sheet 3, and one or a plurality of prism sheets 4, 4... For improving luminance are laminated in this order, and then the prism sheet 4 is formed. The prism sheet 4 is disposed in the backlight housing 1 so as to face the liquid crystal display panel 5 and to be substantially flush with the panel receiving surface 11a of the panel placement step 11. In addition, optical films other than the above may be appropriately laminated.

  The plurality of optical films 2 to 4 are formed in a flat rectangular shape that is slightly smaller than the flat rectangular opening surrounded by the panel receiving surface 11a of the panel disposing step 11 of the backlight housing 1. In the state where it is disposed in the backlight housing 1, it is between the panel receiving surface 11 a of the panel placement step 11 of the backlight housing 1 and the optical film facing the panel receiving surface 11 a. A gap B1 is formed, and a gap B2 is also formed between the outer peripheral surface of the liquid crystal display panel 5 and the vertical portion 11b of the panel disposing step 11 of the backlight housing 1 facing the liquid crystal display panel 5. Yes.

  The reason why the gaps B1 and B2 are formed in this way is that the backlight housing 1 is made of a synthetic resin, and a slight dimensional error is caused by changes in molding conditions and the like, and this dimensional error is absorbed. is there.

  In addition, a reflector 6 is disposed and integrated with the reflector plate step 12 of the backlight housing 1, and an LED (not shown) is disposed in the backlight housing 1 as a light source. Has been.

  The liquid crystal display panel 5 and the prism sheet 4 facing the liquid crystal display panel 5 are integrated via a double-sided adhesive tape 7 having a rectangular frame shape. The double-sided pressure-sensitive adhesive tape 7 is a flat rectangular shape in which adhesive layers 72 and 73 are laminated and integrated on both surfaces of a base film 71 and the outer shape is substantially the same shape and size as the upper end opening of the backlight housing 1. It is formed in a frame shape.

  The double-sided adhesive tape 7 is disposed on the panel receiving surface 11 a of the panel placement step 11 of the backlight housing 1, and the panel placement step 11 of the backlight housing 1. The width dimension from the outer periphery of the panel receiving surface 11a to the outer periphery of the prism sheet 4 disposed in the opening surrounded by the panel receiving surface 11a of the panel disposing step 11 is The panel receiving surface 11a and the prism sheet 4 of the step portion for disposing the panel of the backlight housing 1 and the liquid crystal display panel 5 are disposed through the double-sided adhesive tape 7 on the entire periphery thereof. Sticking is integrated.

  The synthetic resin constituting the base film 71 of the double-sided pressure-sensitive adhesive tape 7 is not particularly limited. For example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin resins such as polyethylene and polypropylene, Polyvinyl alcohol, polyvinylidene chloride and the like can be mentioned, polyester resins are preferable, and polyethylene terephthalate is more preferable.

  Here, as described above, the backlight housing 1 is made of synthetic resin, and is easily deformed by an external force because the overall rigidity is kept low for weight reduction. A gap B1 is formed between the panel receiving surface 11a of the panel disposing step 11 of the housing 1 and the optical film opposed to the panel receiving surface 11a, particularly the prism sheet 4, and the outer peripheral surface of the liquid crystal display panel 5. A gap B2 is formed between the vertical portion 11b of the panel disposing step portion 11 of the backlight housing 1 facing this.

  In such a state, as shown by the dotted line in FIG. 3, the panel receiving surface 11 a of the panel placement step 11 of the backlight housing 1 is deformed in the direction of approaching or separating from the prism sheet 4. Or when the panel receiving surface 11a of the panel disposition step 11 of the backlight housing 1 is deformed or displaced in the direction away from the liquid crystal display panel 5, as shown by the dotted line in FIG. Deformation stress accompanying this displacement is transmitted to the prism sheet 4 via the double-sided adhesive tape 7, and there is a problem that wrinkles and distortion occur in the prism sheet.

  Therefore, in the present invention, in the adhesive layers 72 and 73 of the double-sided adhesive tape 7, the cohesive force of the adhesive layer 72 facing the prism sheet 4 is lower than the cohesive force of the adhesive layer 73 facing the liquid crystal display panel 5. To prevent the stress generated by the deformation of the backlight casing 1 from being absorbed by the double-sided adhesive tape 7 and transmitted to the prism sheet 4 and to prevent wrinkles and distortions in the prism sheet 4. Yes.

  That is, there is a difference in the cohesive strength of the adhesive layers 72 and 73 of the double-sided adhesive tape 7, and the adhesive that is in contact with both the panel receiving surface 11 a of the panel placement step 11 of the backlight housing 1 and the prism sheet 4. Even if the panel receiving surface 11a of the step 11 for disposing the panel of the backlight housing 1 is relatively displaced with respect to the prism sheet 4, the layer 72 is softly formed and deformed due to the relative displacement. The stress is smoothly absorbed by the adhesive layer 72 and hardly transmitted to the prism sheet 4, and as a result, the prism sheet 4 is not wrinkled or distorted.

  On the other hand, the pressure-sensitive adhesive layer 73 of the double-sided pressure-sensitive adhesive tape 7, that is, the pressure-sensitive adhesive layer 73 in contact with the liquid crystal display panel 5 is formed to have a higher cohesion force than the cohesive force of the pressure-sensitive adhesive layer 72, The liquid crystal display panel 5 is reliably integrated with the backlight housing 1 and the prism sheet 4 via the double-sided adhesive tape 7.

  That is, in the present invention, a difference is provided in the cohesive force of the adhesive layers 72 and 73 of the double-sided adhesive tape 7, and the cohesive force of the adhesive layer 72 in contact with the backlight housing 1 and the prism sheet 4 is reduced to facilitate deformation. In addition, the adhesive layer that is in contact with the liquid crystal display panel 5 is reliably absorbed by immediately absorbing the deformation stress generated with the deformation of the backlight housing 1 and preventing the deformation stress from being transmitted to the prism sheet 4. The cohesive force of 73 is increased to increase the adhesive force, and the backlight housing 1 and the prism sheet 4 and the liquid crystal display panel 5 are firmly integrated.

  The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layers 72 and 73 of the double-sided pressure-sensitive adhesive tape 7 is not particularly limited as long as the cohesive force of the pressure-sensitive adhesive layers 72 and 73 is adjusted as described above. For example, an acrylic pressure-sensitive adhesive, Examples thereof include rubber adhesives and silicone adhesives, and acrylic adhesives are preferable. The pressure-sensitive adhesives constituting the pressure-sensitive adhesive layers 72 and 73 may be the same type or different types.

  The cohesive strength of the adhesive layers 72 and 73 of the double-sided adhesive tape 7 is evaluated as follows. First, a plane rectangular test piece C of 5 mm long × 20 mm wide is cut out from the double-sided adhesive tape. And the connection board D which consists of a 25-micrometer-thick polyethylene terephthalate film on the adhesion layer different from the measuring object of the test piece C is stuck. Note that the connection plate D is adhered to the entire surface of the adhesive layer. Next, as shown in FIG. 5, the test piece C is stuck on the horizontal plane E so that the adhesive layer to be measured is on the horizontal plane E side. In addition, it adjusts so that the horizontal direction (long side direction) of a test piece may correspond to the direction of the tensile force mentioned later.

  Next, a weight F of 200 g is attached to one end of the connection plate D so that a tensile force is applied to the connection plate D in the horizontal direction. In addition, the connection plate D is stuck on the adhesive layer of the test piece C so that the other end surface of the test piece C and the other end surface of the connection plate D are flush with each other. In addition, a detector (not shown) that can measure the amount of movement of the other end of the connection plate D in units of μm is installed.

  Then, the moving distance L in the horizontal direction of the other end edge of the connecting plate D after 3 minutes has passed since the weight is attached to the connecting plate D is measured by a detector in an atmosphere of 23 ° C. Is an index of cohesive strength of the adhesive layer. And it can be judged that the cohesive force of an adhesion layer is so high that the moving distance L of the connection board D is short.

  It is sufficient if there is a difference in cohesive force between the adhesive layers 72 and 73 of the double-sided adhesive tape, and the absolute amount in the above evaluation of the cohesive force of the adhesive layer is not particularly limited. The moving distance L is preferably 100 to 400 μm, more preferably 150 to 350 μm, particularly preferably 200 to 300 μm, and the moving distance L of the adhesive layer 73 having a large cohesive force is preferably 10 to 150 μm, more preferably 15 to The moving distance L of the adhesive layer 72 is preferably 100 μm, particularly preferably 20 to 80 μm, and relatively larger than the moving distance L of the adhesive layer 73.

  If the travel distance L of the adhesive layer 72 having a small cohesive force is less than 100 μm, the flexibility may not be sufficient, and the generation of moire may not be sufficiently prevented. If the distance exceeds 400 μm, the adhesive layer is too flexible and flows out. May end up. Further, if the moving distance L of the adhesive layer 73 having a high cohesive force is out of the range of 30 to 200 μm, moire may not be sufficiently prevented.

  The moving distance L of the adhesive layer 72 having a small cohesive force refers to the moving distance L measured by sticking the adhesive layer 72 on the horizontal plane E, and the moving distance L of the adhesive layer 73 having a large cohesive force is The moving distance L measured by sticking the adhesive layer 73 on the horizontal plane E is said.

  The method for adjusting the cohesive strength of the adhesive layers 72 and 73 of the double-sided adhesive tape 7 is not particularly limited. For example, a method for adjusting the degree of crosslinking of the adhesive constituting the adhesive layers 72 and 73, an adhesive polymer A method of adjusting the molecular weight of the component, a method of adjusting by the blending ratio of the adhesive polymers having different molecular weights, a method of adjusting the addition amount of the adhesive polymer having a flexible skeleton, a method of adjusting the addition amount of the low molecular weight component, etc. The method of adjusting the crosslinking degree of the adhesive which comprises the adhesion layers 72 and 73 is preferable, and it is more preferable to adjust the crosslinking degree of an adhesive by addition of a crosslinking agent.

  In addition, as said crosslinking agent, an isocyanate type crosslinking agent, an epoxy-type crosslinking agent, a chelate type crosslinking agent, an aziridine type crosslinking agent etc. are mentioned, for example, An isocyanate type crosslinking agent is preferable.

  In the above description, the optical film facing the liquid crystal display panel 5 is described as being the prism sheet 4. However, the optical film facing the liquid crystal display panel 5 is not necessarily a prism sheet, and other optical films may be used. Good.

  The liquid crystal display module unit configured as described above is used by being mounted in a small electronic device such as a mobile phone or an electronic dictionary. The liquid crystal display module unit is backed not only at the time of manufacture but also by changes in external force or temperature during use. Even if the light casing 1 is deformed, the deformation stress resulting from the deformation of the backlight casing 1 is hardly transmitted to the optical film 4, and the liquid crystal display module unit provides an excellent liquid crystal display screen.

It is the longitudinal cross-sectional view which showed the liquid crystal display module unit of this invention. It is the disassembled perspective view which showed the liquid crystal display module unit of this invention. It is the model longitudinal cross-sectional view which showed the deformation | transformation state of the backlight housing | casing. It is the model longitudinal cross-sectional view which showed the deformation | transformation state of the backlight housing | casing. It is the schematic diagram which showed the measuring point of the cohesion force of the adhesion layer.

Explanation of symbols

1 Backlight housing
11 Panel placement step
11a Panel receiving surface
12 Steps for disposing the reflector 2 Light guide plate 3 Diffusion sheet 4 Prism sheet 5 Liquid crystal display panel 6 Reflector 7 Double-sided adhesive tape
71 Base film
72 Adhesive layer
73 Adhesive layer A Liquid crystal display module unit B Gap C Test piece D Connection plate

Claims (4)

A panel disposition step is formed on the inner peripheral surface of the frame-shaped backlight case, a liquid crystal display panel is disposed on the panel disposition step, and a plurality of sheets are provided in the backlight case. The liquid crystal display panel and the optical film facing the liquid crystal display panel are integrated with a double-sided adhesive tape disposed on the panel disposition step. In the double-sided pressure-sensitive adhesive tape, the adhesive layers are laminated and integrated on both surfaces of the substrate, and the cohesive force of the adhesive layer facing the optical film is lower than the cohesive force of the adhesive layer facing the liquid crystal display panel. A liquid crystal display module unit characterized by being configured as described above. The liquid crystal display module unit according to claim 1, wherein the double-sided adhesive tape is formed in a frame shape. The liquid crystal display module unit according to claim 1, wherein the optical film facing the liquid crystal display panel is a prism sheet. 2. The liquid crystal display module unit according to claim 1, wherein the cohesive force of the adhesive layer is adjusted by adjusting the degree of crosslinking of the adhesive constituting the adhesive layer.

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