JP2008235023A - Manufacturing method of light guide plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a light guide plate with uniform light emission assured on one hand, and enabling improvement in click feeling of input keys, on the other. <P>SOLUTION: The manufacturing method of the light guide plate comprises steps of: (S1) preparing a base member; and (S3) forming a convex part with a multi-layer structure on the surface of the base member. If an input module is structured by arranging the light guide plate thus manufactured so as its convex part to be overlapped with an input detecting element, an increase of pressing force the input detecting element transmits to the light guide plate can be prevented, so that click feeling of the input keys can be improved. Here, there is no need of forming a hole in the light guide plate for avoiding decrease of the click feeling, that facilitates securing of uniform light emission of the input keys. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a light guide plate, and more particularly, to a method for manufacturing a light guide plate used in a portable device.

  In recent years, with the improvement in performance of portable information terminals such as mobile phones and PDAs (Personal Data Assistants), relatively complex information is often input from an input module. For this reason, from the viewpoint of facilitating the input of information, there is a demand for an improved click feeling of buttons (input keys) of the input module. Furthermore, from the viewpoint of the appearance design of the portable information terminal and the viewpoint of facilitating the input of information in a dark place, it is also required that the input keys emit light uniformly.

  Conventionally, there has been proposed an input module that guides light supplied from a light source such as an LED (Light Emitting Diode) using a light guide plate and emits an input button (for example, Patent Documents 1 and 2). reference).

  FIG. 8 is a partial cross-sectional schematic diagram showing a conventional input module. As shown in FIG. 8, the input module includes a substrate 12, a metal dome switch 13, a protective film 14 formed on the metal dome switch 13, a light guide plate 16, an LED 15 as a light source, and an input key 7. And a rubber sheet 17 on which is formed. A plurality of metal dome switches 13 are installed on the upper surface of the substrate 12. The metal dome switch 13 is installed in a region directly below the input key 7 (a region overlapping the region where the input key 7 is located). A protective film 14 is formed so as to cover the upper surfaces of the metal dome switch 13 and the substrate 12.

  A light guide plate 16 is provided on the protective film 14. In the light guide plate 16, a portion located under the input key 7 has a reflective portion that becomes a light emitting region, and, for example, dots 19 that are a plurality of protrusions are formed. The dots 19 as the reflection pattern are formed on the back side of the light guide plate 16 (surface on the side facing the metal dome switch 13). The dots 19 are formed in a region overlapping with the input key 7. An LED 15 is provided on the substrate 12 at a position facing the end face of the light guide plate 16. The LED 15 has a light emitting surface on its side surface, and is a so-called side light emitting element.

A rubber sheet 17 is disposed on the LED 15 and the light guide plate 16. The rubber sheet 17 is formed with an input key 7 whose surface has, for example, a convex shape. A convex portion 18 is formed on the back side of the input key 7 (the surface on the rubber sheet 17 facing the light guide plate 16). The convex portion 18 is formed to reliably transmit the pressing force to the metal dome switch 13 when the user of the cellular phone presses the input key 7.
JP 2006-324240 A JP 2005-268165 A

  In the conventional input module shown in FIG. 8, a light guide plate 16 is disposed between the input key 7 and a metal dome switch 13 that is an input detection element that detects an input from the input key 7. In this configuration, the pressing force for pressing the input key 7 is transmitted to the metal dome switch 13 through the light guide plate 16. When the input key 7 is pressed, the convex portion 18 comes into contact with the light guide plate 16. The pressing force is transmitted to the light guide plate 16 through the convex portion 18 and the light guide plate 16 is deformed toward the substrate 12, so that a relatively wide area of the flat light guide plate 16 comes into contact with the metal dome switch 13. For this reason, when the metal dome switch 13 is deformed to the substrate 12 side, the pressing force applied to the light guide plate 16 increases and is transmitted to the input key 7 through the contact portion (convex portion 18) between the light guide plate 16 and the rubber sheet 17. Power also increases. That is, the user feels heavy, and there is a problem that the click feeling when the input key 7 is pressed decreases. Here, the click feeling is a response when the input key 7 is pressed and means a sense of contact transmitted to the operator through the input key 7.

  On the other hand, as disclosed in Patent Document 2, a window hole larger than the switch is provided in the light guide plate, and the entire switch is exposed from the window hole, so that the input key and the switch are in direct contact with each other. Therefore, it is possible to avoid a reduction in click feeling. However, in this configuration, a window hole having a planar shape larger than the planar shape of the switch is formed in the light guide plate, so that there is a problem that uniform light emission of the input key becomes difficult.

  Therefore, a main object of the present invention is to provide a method of manufacturing a light guide plate that can improve the click feeling of an input key while ensuring uniform light emission.

  The manufacturing method of the light-guide plate used for a portable apparatus based on this invention comprises the process of preparing a base member, and the process of forming the convex part which has a multilayer structure on the surface of a base member. If the light guide plate manufactured in this way is arranged so that the convex portion overlaps the input detection element to constitute the input module, the input detection element contacts the convex portion when the input key is pressed. Since the portion of the light guide plate that contacts the input detection element is limited to the convex portion, it is possible to prevent an increase in pressing force transmitted from the input detection element to the light guide plate, thereby improving the click feeling of the input key. At this time, since it is not necessary to form a hole in the light guide plate in order to avoid a reduction in click feeling, it is easy to ensure uniform light emission of the input key.

  Moreover, it is desirable that the step of forming the convex portion includes a step of forming at least one layer of the multilayer structure by screen printing. In this case, the light guide plate can be easily mass-produced to form the multilayer structure of the convex portions by screen printing, which is an excellent manufacturing technique capable of mass production simply and at low cost. In addition, convex portions having various shapes and dimensions can be easily manufactured.

  According to the light guide plate manufacturing method of the present invention, it is possible to manufacture a light guide plate that can improve the click feeling of the input key while ensuring uniform light emission.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic perspective view showing a foldable mobile phone using a light guide plate manufactured by the manufacturing method of the present invention. FIG. 2 is a schematic plan view showing an input module that constitutes the input unit of the mobile phone shown in FIG. 3 is a partial cross-sectional schematic view taken along line III-III in FIG. FIG. 4 is a schematic diagram showing the vicinity of region IV in FIG. 3 in an enlarged manner. The mobile phone 1, the input module 10, and the light guide plate 16 constituting the input module 10 will be described with reference to FIGS.

  As shown in FIG. 1, the mobile phone 1 includes an input unit 4 and a display unit 3 connected via the input unit 4 and a hinge unit 5. The input unit 4 and the display unit 3 can be opened and closed by rotating about the hinge unit 5 as a rotation center. The display unit 3 is provided with a display device 6 using a liquid crystal display device (LCD). A speaker 8 is installed above the display device 6 of the display unit 3 (the end of the display unit 3 opposite to the side where the hinge unit 5 is located when viewed from the display device 6).

  The input unit 4 has a plurality of input keys 7 for inputting symbols such as telephone numbers and alphabets. A microphone 9 is installed at the end of the input unit 4 opposite to the side connected to the hinge unit 5.

  In the input unit 4 described above, as shown in FIG. 2, an input module 10 provided with a plurality of input keys 7 is arranged inside the casing. That is, the input unit 4 includes a housing in which a plurality of openings from which the input keys 7 are exposed is formed, and an input module 10 as shown in FIG. 2 installed inside the housing. In the opening described above, the input key 7 of the input module 10 is exposed.

  As shown in FIG. 3, the input module 10 includes a substrate 12, a metal dome switch 13, a protective film 14 formed on the metal dome switch 13, a light guide plate 16, an LED 15 as a light source, and an input key. 7 and a rubber sheet 17 on which 7 is formed. Specifically, as shown in FIG. 3, a plurality of metal dome switches 13 are installed on the upper surface of the substrate 12. The metal dome switch 13 is installed in an area directly below the input key 7 shown in FIG. 2 (an area overlapping the area where the input key 7 is located). A protective film 14 is formed so as to cover the upper surfaces of the metal dome switch 13 and the substrate 12. Any material can be used as the material of the protective film 14.

  A light guide plate 16 is provided on the protective film 14. As a material of the light guide plate 16, any material can be used as long as it is a translucent material. For example, a polycarbonate resin, an acrylic resin, a cycloolefin resin, or the like can be used. Further, the thickness of the light guide plate 16 can be set to 0.02 mm or more and 1.0 mm or less which is easy to transmit a pressing force by a key input and is effective for transmitting light. The planar shape of the light guide plate 16 is substantially rectangular as shown in FIG. Further, in the light guide plate 16, as shown in FIG. 3, a portion located below the input key 7 has a reflective portion serving as a light emitting region, and for example, a plurality of protrusions 19 and projections 20 are formed. ing. The dots 19 and the projections 20 as the reflection pattern are formed on the back side of the light guide plate 16 (the surface on the side facing the metal dome switch 13). The dot 19 is formed in a region overlapping the input key 7 so as to surround the convex portion 20.

  The convex part 20 has a multilayer structure, as shown in FIG. In this case, the convex part 20 shall be a 4 layer structure comprised by the layers 20a-20d. Each of the layers 20a to 20d can be formed by screen printing. All of the layers 20a to 20d may be formed by screen printing. Alternatively, at least one layer of the convex portion 20 having a multilayer structure may be formed by screen printing, and the other layers may be formed by another method. Screen printing is a method of forming a pattern by placing a paste (a kind of ink made of a forming material) on a screen with holes in the pattern shape to be formed, and extruding the paste with a squeegee (rubber spatula). It is.

  In consideration of durability, for example, an acrylic resin, a urethane resin, a silicon resin, or the like can be used as the material of the convex portion 20. Moreover, the thickness of the convex part 20 can be 0.003 mm or more and 3.0 mm or less, for example.

  An LED 15 is installed on the substrate 12 at a position facing the end face of the light guide plate 16. The LED 15 has a light emitting surface on its side surface, and is a so-called side light emitting element. As shown in FIG. 2, the substantially rectangular light guide plate 16 can have a shape in which the same number of notches as the number of LEDs 15 are formed on the outer periphery of the rectangle. Then, the LED 15 that supplies light to the light guide plate 16 can be disposed at the position of the notch so that the light emitting surface of the LED 15 faces the outer peripheral end surface of the light guide plate 16. That is, the LED 15 can supply light to the light guide plate 16 at the outer peripheral end face of the cutout portion of the light guide plate 16. In this way, light can be supplied from the light source (LED 15) to the light guide plate 16 without forming holes in the light guide plate 16 for arranging the LEDs 15.

  Although two LEDs 15 are installed on the substrate 12 in FIG. 2, the number of LEDs 15 is not limited to two, and may be one or three or more. The light guide plate 16 is not formed with a notch, and the LEDs 15 are arranged so as to face the outer peripheral side of the light guide plate 16 on the straight line, and the light guide plate 16 on the outer peripheral end surface of the outer peripheral side on the straight line. The light may be supplied to the light source. Moreover, you may arrange | position so that several LED15 may oppose the corner | angular part or several side of the polygonal light-guide plate 16. FIG.

  A rubber sheet 17 is disposed on the LED 15 and the light guide plate 16 as shown in FIG. The rubber sheet 17 is formed with an input key 7 whose surface has, for example, a convex shape. The input key 7 may have a planar shape that does not have a convex shape. The light guide plate 16 and the rubber sheet 17 may be arranged so as to cover a part of the surface of the substrate 12 as shown in FIG. All the input keys 7 of the module 10 may be formed on the rubber sheet 17, and the light guide plate 16 having substantially the same size as the rubber sheet 17 may be disposed.

  Next, the manufacturing method of the light-guide plate 16 in which the convex part 20 shown in FIG. 3 was formed is demonstrated. FIG. 5 is a flowchart showing a method for manufacturing the light guide plate. As shown in FIG. 5, first, in step (S1), a light guide plate 16 as a base member, which is a component that converts light from a point light source such as an LED 15 into a surface light source, is prepared.

  In the step (S1), a light guide plate 16 in which dots 19 as reflection patterns for reflecting and diffusing light are formed on the back surface side can be prepared. In this case, the light guide plate 16 on which the dots 19 are formed can be manufactured according to an injection molding method using a mold in which the pattern of the dots 19 is engraved. Further, in the step (S1) or a post-processing step (S4) to be described later, for example, a machining method using an NC machine tool, a laser processing method for engraving a dot 19 pattern with a laser, and a resin material on the back side of the light guide plate The dots 19 may be formed on the surface of the light guide plate 16 by an ink jet method in which the dots 19 are printed by being ejected onto the surface, or an imprint method in which a die is pressed against the light guide plate 16 to transfer the dots 19.

  Subsequently, in step (S2), it is determined whether the number of screen printings reaches a predetermined value for the multilayer structure formed by screen printing. If it is determined that the number of screen printings has not reached the predetermined value, screen printing is performed on the rear surface of the light guide plate 16 in step (S3), and one of the multilayer structures constituting the convex portion 20 is formed. Form. Thereafter, the determination in step (S2) is performed again.

  When it is determined in step (S2) that the number of times of screen printing has reached a predetermined value (for example, in the case of the convex portion 20 shown in FIG. 4, screen printing has been performed four times), a predetermined multilayer structure is provided. The convex part 20 is formed. Thereafter, in the post-processing step (S4), the light guide plate 16 is formed into a predetermined shape optimally used for the input module, for example, by punching. Thus, the convex part 20 having a multilayer structure formed by screen printing can be formed on the surface on the back surface side of the light guide plate 16.

  If the light guide plate 16 manufactured in this way is arranged so that the convex portion 20 overlaps the metal dome switch 13 to constitute the input module, the metal dome switch 13 will be projected when the input key 7 is pressed. To touch. Since the portion of the light guide plate 16 that contacts the metal dome switch 13 is limited to the convex portion 20, it is possible to prevent an increase in pressing force transmitted to the light guide plate 16 by the metal dome switch 13, thereby improving the click feeling of the input key 7. Can be made. At this time, since it is not necessary to form a hole in the light guide plate 16 in order to avoid a decrease in click feeling, it is easy to ensure uniform light emission of the input key 7.

  Moreover, in order to form the multilayer structure 20a-20d of the convex part 20 by the screen printing which is the outstanding manufacturing technology which can be mass-produced simply and cheaply, the light-guide plate 16 in which the convex part 20 was formed easily Can be mass produced. Moreover, the convex part 20 of various shapes and dimensions, such as a truncated cone, an elliptical truncated cone, and a hexahedron having a trapezoidal side surface, can be easily manufactured. The convex portion 20 can be formed by cutting the surface of the light guide plate 16 by machining or the like, but in this case, it is difficult to produce the convex portion 20 and the thickness of the light guide plate 16 is reduced. There arises a problem that the transmission path of the narrower. Therefore, the manufacturing method which forms the convex part 20 by screen printing demonstrated in Embodiment 1 is more advantageous.

(Embodiment 2)
FIG. 6 is a partial cross-sectional schematic diagram showing the input module of the second embodiment. The input module according to the second embodiment and the input module according to the first embodiment described above basically have the same configuration. However, the second embodiment is different from the first embodiment in that a convex portion 18 is formed on the rubber sheet 17.

  According to such a configuration, when the pressing force for pressing the input key 7 is the same, the force per unit area transmitted to the metal dome switch 13 becomes larger and the touch is good. That is, by forming the convex portion 18 and the convex portion 20, the contact area between the metal dome switch 13 and the light guide plate 16 and the contact area between the light guide plate 16 and the rubber sheet 17 become smaller. Therefore, when the user of the mobile phone presses the input key 7, a larger pressing force can be reliably transmitted to the metal dome switch 13. Therefore, a better click feeling can be obtained when the input key 7 is pressed.

(Embodiment 3)
FIG. 7 is a partial cross-sectional schematic diagram showing the input module of the third embodiment. The input module of the third embodiment is different from the conventional input module shown in FIG. 8 in that a rib 30 having a pillar structure as a strength member is formed. The rib 30 functions as a strength member that supports the light guide plate 16 at a position away from the surface of the substrate 12 by a predetermined distance. That is, the light guide plate 16 is supported on the substrate 12 by the pillar-shaped ribs 30 so as to cover a part of the surface of the substrate 12.

  The ribs 30 can be formed in a multilayer structure by screen printing, similar to the protrusions 20. That is, the rib 30 having a multilayer structure can be formed on the surface of the light guide plate 16, and at least one of the multilayer structures of the rib 30 can be formed by screen printing. If the ribs 30 are formed by screen printing, the ribs 30 having any shape can be easily provided at any position on the surface of the light guide plate 16. That is, since the column structure that supports the light guide plate 16 can be provided at an arbitrary position on the substrate 12, the degree of freedom in design when arranging each component of the input module can be increased. Therefore, it is possible to reduce the size of the input module.

  In the description of the first to third embodiments, an example in which the convex portion 20 (or rib 30) having a multilayer structure is formed by screen printing is described, but the method for forming the multilayer structure is limited to this. It is not a thing. For example, a convex portion having a multilayer structure may be formed by irradiating a photocurable resin with predetermined light such as ultraviolet rays to be cured into a thin plate shape, and laminating the photocurable resin cured in the thin plate shape. . Further, for example, a convex portion having a multilayer structure may be formed by attaching a film made of a resin material such as PET (polyethylene terephthalate), polyimide, or PEN (polyethylene naphthalate).

  In addition, although the example in which the light guide plate manufactured by the manufacturing method of the present invention is used for a foldable mobile phone has been described, it can also be applied to a straight type or flip type mobile phone. Further, the light guide plate manufactured by the manufacturing method of the present invention can be applied not only to a cellular phone but also to a portable information terminal such as a PDA (personal data assistant), a notebook personal computer, and a digital camera capable of communication. .

  The embodiment disclosed this time is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a perspective schematic diagram which shows the mobile telephone in which the light-guide plate manufactured by the manufacturing method of this invention is used. It is a plane schematic diagram which shows the input module which comprises the input part of the mobile telephone shown in FIG. FIG. 3 is a partial cross-sectional schematic view taken along line III-III in FIG. 2. It is a schematic diagram which expands and shows the area | region IV of FIG. It is a flowchart which shows the manufacturing method of a light-guide plate. FIG. 6 is a partial cross-sectional schematic diagram illustrating an input module according to a second embodiment. FIG. 9 is a partial cross-sectional schematic diagram illustrating an input module according to a third embodiment. It is a partial cross-section schematic diagram which shows the conventional input module.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Mobile phone, 3 Display part, 4 Input part, 5 Hinge part, 6 Display apparatus, 7 Input key, 8 Speaker, 9 Microphone, 10 Input module, 12 Board | substrate, 13 Metal dome switch, 14 Protective film, 15 LED, 16 Light guide plate, 17 rubber sheet, 18 convex portions, 19 dots, 20 convex portions, 20a, 20b, 20c, 20d layers, 30 ribs.

Claims (2)

A method of manufacturing a light guide plate used in a portable device,
Preparing a base member;
Forming a convex part having a multilayer structure on the surface of the base member.   The method of manufacturing a light guide plate according to claim 1, wherein the step of forming the convex portion includes a step of forming at least one layer of the multilayer structure by screen printing.

Images