JP2011159565A - Dome sheet, printed wiring board, key module and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dome sheet, which prevents a malfunction in a portable information terminal device, and also prevents abnormal light emission or the like by flatly holding a lightguide plate and a key top sheet. <P>SOLUTION: The dome sheet 13 is laminated on a printed wiring board 10 having switch electrodes 11a, 11b, and has a metal dome 15 which is elastically deformed by pressing operation to mutually connect the switch electrodes. The dome sheet 13 has a spacer 31 provided in an area other than the pressing operation area on the opposite side of the side having the metal dome, the spacer securing a gap S with the lightguide plate 16 or key top sheet 19 to be overlapped on the opposite side of the printed wiring board. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dome sheet, a printed wiring board, a key module, and an electronic device. More specifically, the present invention relates to a dome sheet or the like that can prevent an erroneous operation when pressing an operation area of a key top sheet.

  As an operation switch of a portable information terminal device such as a cellular phone, there are many devices including a key top sheet in which operation buttons are provided by printing or the like. Information is input by pressing a predetermined area of the key top sheet.

  The operation switch includes a fixed-side switch electrode provided on a substrate, a resin dome sheet for arranging and holding a metal dome at a predetermined position, and the key top sheet. The metal dome is formed in a bowl shape that can be pressed and deformed, and is disposed on a resin sheet so as to cover the switch electrode. In a mobile phone or the like, there is a light guide plate that introduces light from a light emitting element provided on a side portion between the key top sheet and the dome sheet and irradiates the key top sheet side at a predetermined portion. It is inserted. The light emitted from the light guide plate is used as a backlight for raising letters, numbers, and the like provided on the key top sheet.

  When the operation area on the surface of the key top sheet is pressed, the pressing force is transmitted to the metal dome via the light guide plate or the dome sheet, and the metal dome is elastically deformed. Thereby, the switch electrode on the printed wiring board is made conductive. On the other hand, when the pressing force is released, the metal dome returns to its original form by the elastic restoring force, and the conduction between the switch electrodes is released. Thereby, the switch electrode provided on the printed wiring board is turned on and off.

JP 2009-21114 A

  With the rapid spread of portable information terminal devices such as mobile phones, there is a demand for downsizing, higher functionality, and improved usability of these devices. The number of input keys of the portable information terminal device is large, and the pressing operation area per key is reduced due to the downsizing of the device. On the other hand, in order to input a large amount of information in a short time, the speed at which the user operates the key top sheet is high.

  As described in Patent Document 1, the metal domes are arranged and held on the dome sheet at intervals corresponding to switch electrodes formed on a printed wiring board. A gap is provided between the dome sheet and the key top sheet or the light guide plate to ensure the amount of pressing operation of the metal dome.

  In the operation switch having the above-described configuration, when an intermediate portion of the operation region is accidentally pressed, a pressing force acts on any of the adjacent metal domes and is deformed. For this reason, switch electrodes other than the switch electrode to be operated are often conducted, or two or more switch electrodes are often conducted.

  Further, the above-described gap exists also in an area other than the above-described pressing operation area, for example, between adjacent pressing operation areas or in the peripheral edge of the pressing operation area. The top sheet and the light guide plate are pressed against the dome sheet. For this reason, the dome sheet and the light guide plate or the key top sheet are attached by a pressing operation, and a problem that the surface of the key top sheet is uneven is likely to occur.

  Furthermore, when the light guide plate is deformed or comes into contact with the dome sheet, there is a problem that it is impossible to emit light at a required portion or abnormal light emission occurs.

  The present invention provides a dome sheet that can prevent an erroneous operation in a portable information terminal device and the like, and can prevent abnormal light emission and the like by holding the light guide plate and the key top sheet flat.

  The invention described in claim 1 of the present application is a dome sheet provided with a metal dome that is laminated on a printed wiring board provided with a switch electrode and elastically deformed by a pressing operation to make the switch electrode conductive, A spacer is provided in a region other than the pressing operation region on the side opposite to the side where the metal dome is provided, and a spacer is provided to ensure a gap between the light guide plate or the key top sheet superimposed on the side opposite to the printed wiring board. Is.

  The present invention can be applied to various switches that perform an on-off operation by deforming a metal dome by a pressing operation. For example, the inner surface of the key top sheet is configured to directly press the dome sheet, or a light guide plate is inserted between the key top sheet and the dome sheet so that the pressing force applied to the key top sheet is reduced. The present invention can be applied to those configured to deform the dome sheet via the light guide plate.

  When the spacer according to the present invention is provided on the dome sheet, a gap between the dome sheet and the key top sheet or the light guide plate is secured. Therefore, even if the spacer forming portion is pressed, the key top sheet and the light guide plate are not deformed. Therefore, the pressing force does not act on the nearby metal dome. As a result, when a portion other than the pressing operation region is pressed, the metal dome other than the desired operation key is not deformed and the switch electrode is not conducted, and an erroneous operation can be prevented.

  In addition, the dome sheet can be reliably separated from the key top sheet and the light guide plate at or near the portion where the spacer is provided. For this reason, the dome sheet, the key top sheet and the light guide plate do not come into contact with each other, and these members do not stick to each other. For this reason, the key top sheet and the light guide plate are not deformed to cause unevenness on the surface of the operation unit, and the flatness of these members can be ensured. Moreover, abnormal light emission due to the light guide plate coming into contact with the dome sheet can be prevented.

  The position where the spacer is provided is not particularly limited as long as it is an area other than the pressing operation area. For example, in order to prevent an adjacent switch from being erroneously operated, the spacer can be provided at an intermediate portion between adjacent pressing operation areas. Moreover, in order to ensure the flatness of a key top sheet and a light-guide plate, it can also provide in wide area | regions other than a press operation area | region.

  In order to prevent an erroneous operation, it is preferable to provide the spacer at the peripheral edge of the pressing operation area as in the invention described in claim 2. By providing the spacer on the peripheral edge of the pressing operation area, it is possible to configure the switch so that the switch can be turned on and off only when the inside of the pressing operation area is pressed, and erroneous operation can be reliably prevented.

  The form of the spacer is not particularly limited. For example, a spacer having a columnar protrusion shape such as a columnar shape or a prism shape can be provided. Further, it is also possible to provide a ridge along the edge of the pressing operation area or a cross-shaped spacer in plan view. Furthermore, in order to ensure the smoothness of the key top sheet or the light guide plate, a flat spacer having a large area may be provided.

  Further, the number of spacers is not particularly limited. A plurality of spacers can be provided for one switch electrode. For example, a plurality of columnar spacers can be provided between adjacent pressing operation areas.

  The method for providing the spacer is not particularly limited. For example, as in the invention described in claim 3, the spacer can be provided on the dome sheet by molding. For example, after coating the sheet-like base material constituting the dome sheet with an ultraviolet curable resin with a predetermined thickness, pressing a transfer mold having a concave portion corresponding to the spacer to provide a convex portion protruding from the dome sheet surface, Then, the said spacer can be provided by irradiating an ultraviolet-ray and hardening the said resin. Further, the spacer can be provided by other mold forming methods.

  Moreover, like the invention described in Claim 4, the said spacer can be stuck and provided in the said dome sheet | seat through an adhesive layer. For example, the spacer can be provided by adhering a member having a predetermined thickness functioning as a spacer to a predetermined portion of the dome sheet using an adhesive. When the spacer is formed by bonding, the spacer can be provided using a material that cannot be directly molded on the dome sheet.

  Further, the spacer can be provided by dropping a resin material such as an ultraviolet curable resin having a high viscosity onto a predetermined portion of the dome sheet and curing the resin material in a raised state from the surface.

  The kind and form of the material constituting the spacer are not particularly limited. In addition to the ultraviolet curable resin, various resin materials can be employed.

  As in the invention described in claim 5, the spacer can be provided on the resin coating layer laminated on the surface of the dome sheet including the pressing operation region.

  Positioning or the like can be easily performed by providing a resin coating layer having protrusions constituting the spacers on the entire dome sheet. As a result, not only can the manufacturing be performed easily, but also the spacer can be provided at a desired location with high accuracy. Moreover, the joining strength of the spacer with respect to the dome sheet can be ensured.

  For example, the spacer can be provided by producing a resin sheet having a predetermined shape of the protrusion that constitutes the spacer in advance and adhering it to the dome sheet via an adhesive. In addition, the resin coating layer and the spacer can be integrally formed on the surface of the dome sheet by molding.

  In the invention described in claim 5, when the resin coating in the pressing operation region becomes thick, the click feeling of the metal dome may be lowered or the operability may be lowered. In such a case, the part corresponding to the said press operation area | region of the said resin coating layer can also be notched like the invention described in Claim 6. The cutting method is not particularly limited. For example, it can be cut out using a punch or the like.

  The dome sheet according to the present invention is not only combined with a sheet-like key top in which a plurality of operation keys are set, but also combined with a sheet-like key top divided for each operation key or for each of the plurality of keys. It can also be applied to cases. Further, as in the invention described in claim 7, it can be applied to various printed wiring boards in which a dome sheet is integrally provided. Furthermore, as in the invention described in claim 8, it can be applied to various key modules configured to include a printed wiring board and the dome sheet. Further, the present invention can be applied not only to a key module including a light guide plate but also to a key module not including a light guide plate.

  Moreover, the electronic device to which the dome sheet according to the present invention is applied is not limited, and can be applied to various electronic devices.

  In addition to preventing erroneous operation, the flatness of the light guide plate and key top sheet can be ensured.

It is an external view of an example of a portable information terminal device to which a dome sheet according to the present invention is applied. It is a top view of the operation part of the portable terminal device shown in FIG. It is an enlarged view of the principal part in FIG. It is a figure which shows a key module provided with the dome sheet | seat which concerns on 1st Embodiment, and is an expanded sectional view which follows the IV-IV line in FIG. It is a figure which shows a key module provided with the dome sheet | seat which concerns on 2nd Embodiment, and is an expanded sectional view corresponding to FIG. It is a figure which shows a key module provided with the dome sheet | seat which concerns on 3rd Embodiment, and is an expanded sectional view corresponding to FIG. It is a figure which shows a key module provided with the dome sheet | seat which concerns on 4th Embodiment, and is an expanded sectional view corresponding to FIG. It is a figure which shows the modification of the spacer which concerns on 1st Embodiment, and is a top view corresponding to FIG.

  Embodiments of the present invention will be specifically described below with reference to the drawings. 1 to 3 show a portable terminal device to which the present invention is applied. In this embodiment, the present invention is applied to an operation switch of a foldable mobile phone.

  The cellular phone 1 is configured to include an upper layer casing 2 and a lower layer casing 3, and the edge portion is connected via a hinge portion 5 so as to be openable and closable so that the casings can be folded and stacked. Has been.

  On the inner surface of the upper casing 2 is provided a display unit 2a composed of a liquid crystal display. On the other hand, the inner surface of the lower casing 3 is provided with an operation section in which a plurality of operation keys 4a to be pressed are arranged.

  As shown in FIGS. 2 and 3, the operation key 4a is configured to display the pressing operation region 4 by providing characters, symbols, frame lines, etc. on the surface of the key top sheet 19 formed of a resin sheet. Has been. And it is comprised so that information can be input by pressing this pressing operation area | region 4. FIG.

  FIG. 4 is a cross-sectional view of a main part taken along line IV-IV in FIG. 4 is a view showing a cross section of the switch portion of the key module 100 provided on the key top sheet side provided with the operation key 4a, and does not show the entire cross section of the mobile phone 1. FIG.

  The key module 100 according to the present embodiment is arranged with a flexible printed wiring board 10 on which a switch circuit 11 is formed, a dome sheet 13 that holds a metal dome 15, and a predetermined gap S outside the dome sheet 13. The light guide plate 16 is configured to include a key top sheet 19 that is superimposed on the outside of the light guide plate 16.

  The switch circuit 11 is formed of a wiring 12 formed of a conductive material such as copper on an insulating base sheet 10a, and presses the key top sheet 19 in a portion corresponding to the pressing operation region 4. Switch electrodes 11a and 11b that are opened and closed by operation are provided.

  The dome sheet 13 is formed with an elastically deformable resin sheet such as polyethylene terephthalate, and a metal dome 15 is held at a portion of the resin sheet facing the switch electrodes 11a and 11b. The metal dome 15 is a bowl-shaped member made of a conductive metal material, and is held so that the peripheral edge is in contact with the outer switch electrode 11a.

  The switch electrode 11a that is brought into contact with the peripheral edge of the metal dome 15 by pressing and deforming so that the bulging top of the metal dome 15 is recessed and contacting the switch electrode 11b disposed on the inside. The switch electrode 11b disposed inside is electrically connected.

  An adhesive layer 14 is provided on the surface of the dome sheet 13 that faces the flexible printed wiring board 10, holds the metal dome 15, and is joined to the flexible printed wiring board 10.

  The light guide plate 16 is formed of a resin material having excellent light guide properties such as acrylic resin, silicon resin, polycarbonate resin, polyethylene terephthalate, and the like, and light is introduced from an LED light source (not shown) provided on the side. This light is guided while being totally reflected in the light guide plate.

  At a predetermined position of the light guide plate 16, an illumination unit 17 is provided for emitting light guided into the light guide plate from the surface. The illumination unit 17 is formed by providing irregularities or the like on the surface of the light guide plate 16 or by providing reflective dots, and the light reflected from the illumination unit is transmitted from the surface of the light guide plate 16 to the key top sheet 19. It is comprised so that it may irradiate to the back side. A portion of the light guide plate 16 corresponding to the metal dome 15 is provided with a protrusion 18 for pressing the top of the metal dome 15.

  The key top sheet 19 is formed of a flexible resin sheet such as polyethylene terephthalate, and the pressing operation area 4 is displayed by providing characters, symbols, frame lines, and the like on the surface. Further, a protrusion 20 is provided on the outer surface side of the central portion of the pressing operation area 4 to make the user recognize the center of the operation area. The key top sheet 19 and the light guide plate 16 are joined via an adhesive layer 21.

  As shown in FIG. 4, the dome sheet 13 according to the present embodiment secures a gap S between the dome sheet 13 and the light guide plate 16 on the side opposite to the side where the metal dome 15 is provided. A spacer 31 is provided. As shown in FIG. 3, the spacer 31 according to the present embodiment is provided between the pressing regions 4 and 4 adjacent to each other in the vertical direction.

  The spacer 31 is formed in a cylindrical shape, has a height substantially corresponding to the height of the metal dome 15, and is formed so that the upper end portion contacts the inner surface of the light guide plate 16. In the present embodiment, the upper end portion of the spacer 31 is configured to contact the light guide plate 16, but a slight gap may be formed.

  The spacer 31 is formed integrally with the resin coating layer 30 formed on the dome sheet 13 in a laminated manner.

  The method for forming the spacer 31 and the resin coating layer 30 is not particularly limited. The resin coating layer 30 and the spacer 31 of the above form can be formed by the following method, for example.

  First, an ultraviolet curable resin is applied with a predetermined thickness on a sheet constituting the dome sheet 13. Thereafter, a transfer mold having a recess corresponding to the spacer 31 is pressed against the ultraviolet curable resin on the sheet to transfer and form the protrusions constituting the spacer 31. And the said ultraviolet curing resin is hardened by irradiating an ultraviolet-ray. Thereby, the resin coating layer 30 and the spacer 31 can be formed integrally with the dome sheet 13.

  By providing the spacer 31, a gap S between the dome sheet 13 and the light guide plate 16 is secured in the pressing operation region. Therefore, even if the portion corresponding to the portion where the spacer 31 is formed on the key top sheet 19 is pressed, the key top sheet 19 and the light guide plate 16 are not deformed. For this reason, the pressing force does not act on the nearby metal dome 15. As a result, the metal dome other than the desired operation key is not deformed and the switch electrodes 11a and 11b are not turned on, and an erroneous operation can be prevented.

  Further, the dome sheet 13 and the light guide plate 16 can be reliably separated from each other at or near the portion where the spacer 31 is provided. For this reason, the dome sheet 13 and the light guide plate 16 do not come into contact with each other, and these members do not stick to each other. Further, the key top sheet 19 and the light guide plate 16 are not deformed to cause unevenness, and the flatness of these members can be ensured. Furthermore, abnormal light emission due to the light guide plate 16 coming into contact with the dome sheet 13 can be prevented.

  The position where the spacer 31 is provided is not particularly limited as long as it is an area other than the pressing operation area 4. In the present embodiment, as shown in FIG. 3, the spacer 31 is provided in an intermediate portion between the upper and lower operation areas 4, but can be provided in a part other than the operation area.

  Moreover, in this embodiment, although the columnar spacer 31 was provided, the form of the spacer 31 is not specifically limited. For example, a substantially cross-shaped spacer 531 can be provided so as to surround the corner of the pressing operation region 4 as in the modified example of the spacer according to the first embodiment shown in FIG. Further, a frame-shaped spacer surrounding the peripheral edge of the pressing operation region 4 can be provided. Furthermore, a flat spacer can be provided so as to fill an area other than the pressing operation area.

  FIG. 5 shows a second embodiment of the present invention. Since members other than the spacer 231 are the same as those in the first embodiment described above, the description thereof is omitted.

  In this embodiment, a spacer 231 having a mountain-shaped cross section is provided at the edge of the region corresponding to the pressing operation region of the dome sheet 213.

  The spacer 231 is formed by dropping an ultraviolet curable resin on the dome sheet 213 and curing it while maintaining the mountain shape.

  By providing the spacer 231 according to the second embodiment, the same effect as that of the first embodiment can be exhibited. In addition, the position where the spacer 231 is provided may be an area other than the pressing operation area, and the number of spacers is not particularly limited.

  FIG. 6 shows a third embodiment of the present invention.

  In this embodiment, a resin sheet 330 in which protrusions constituting the spacer 331 are integrally formed is attached via an adhesive layer 344.

  In the present embodiment, the resin sheet 330 in which the spacer 331 is integrally formed can be separately formed. Therefore, it is possible to employ a resin material that cannot directly form a resin coating layer on the dome sheet 313. For example, the spacer 331 can be formed using silicon resin or the like.

  FIG. 7 shows a fourth embodiment of the present invention.

  In the present embodiment, the spacer 431 is formed on the sheet 453 serving as a base material by the same method as in the first embodiment, and a portion corresponding to the pressing operation region 404 is cut out. Thereafter, the sheet 453 is attached to the surface side of the dome sheet 413 through the adhesive layer 444.

  When a resin sheet 430 having a large thickness is laminated on the pressing operation region of the dome sheet 413, the click feeling of the metal dome may be lowered or the operability may be lowered. For example, when the spacer is provided using silicon resin or the like, the thickness of the pressing operation region is increased. In the present embodiment, the dome sheet 413 is configured to be directly pressed through the light guide plate 416 by cutting away a portion of the resin sheet 430 corresponding to the pressing operation region 404. Thereby, the spacer 431 can be provided without impairing the click feeling of the metal dome.

  The scope of the present invention is not limited to the embodiment described above. The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  In addition to preventing erroneous operation in the portable information terminal device, abnormal light emission and the like can be prevented by holding the light guide plate and the key top sheet flat.

DESCRIPTION OF SYMBOLS 1 Portable information terminal device 4 Press operation area | region 10 Printed wiring board 11a Switch electrode 11b Switch electrode 13 Dome sheet 15 Metal dome 16 Light guide plate 19 Key top sheet 31 Spacer S Crevice

Claims (9)

A dome sheet comprising a metal dome that is laminated on a printed wiring board provided with a switch electrode and elastically deformed by a pressing operation to conduct the switch electrode,
In a region other than the pressing operation region on the side opposite to the side where the metal dome is provided, a spacer is provided to ensure a gap between the light guide plate or the key top sheet superimposed on the side opposite to the printed wiring board. , Dome sheet.   The dome sheet according to claim 1, wherein the spacer is provided at a peripheral portion of the pressing operation area.   The dome sheet according to claim 1, wherein the spacer is molded on the dome sheet.   The dome sheet according to claim 1, wherein the spacer is affixed to the dome sheet via an adhesive layer.   The dome sheet according to any one of claims 1 to 4, wherein the spacer is provided on a resin coating layer laminated on a surface of the dome sheet including a pressing operation region.   The dome sheet according to claim 5, wherein a portion of the resin coating layer corresponding to the pressing operation region is cut out.   A printed wiring board comprising the dome sheet according to any one of claims 1 to 6.   A key module comprising the dome sheet according to any one of claims 1 to 6.   An electronic device comprising the dome sheet according to any one of claims 1 to 6.

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