JP2010205451A - Light source positioning structure of keyboard unit for back light - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source positioning structure for realizing positioning accuracy of an LED and a light guiding plate, by butting the light guiding plate against a flexible substrate. <P>SOLUTION: This light source positioning structure of a keyboard unit for the back light includes the light guiding plate 4, a spotted light source (LED) 7 and the flexible substrate 5. The light guiding plate 4 includes a plurality of projections 10 and recessed parts on an end surface on the light incident surface side. The flexible substrate 5 includes a plurality of slits 15 arranged in response to the plurality of projections 10, the LED 7 arranged between the slits or in parallel to the slits 15, and an adhesive member formed in an overlapping part of the flexible substrate 5 and the light guiding plate 4. The respective projections 10 are inserted into the slits arranged on the flexible substrate 5. The light guiding plate 4 is fixed to the flexible substrate 5 so that a distance up to a light incident surface of the light guiding plate 4 from a light emitting surface of the spotted light source 7, becomes a proper distance regulated in a minimum tolerance range, in a position for butting a peripheral edge part of the slits 15 against a base end part outside surface of the projections 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a backlight keyboard unit used for a keyboard or the like as an input unit of a computer, and in particular, to locate a light source that stabilizes the positional relationship between a light emitting element of a point light source and a light guide plate arranged on a flexible substrate. Concerning structure.

  In recent years, keyboards used in electronic devices such as personal computers have become more and more multifunctional. For example, a keyboard in which a phosphorescent material is mixed in characters, symbols, designs, etc. so that the key top can be identified even in a dark place. There are also keyboards that illuminate the display of characters, symbols, designs, etc. from the bottom.

  Therefore, in order to realize downsizing and low power consumption of the illumination means that illuminates from the lower surface, a light source that uses an LED as a point light source as the light source of the illumination means or a light emitting element that is fixed at a predetermined position to emit light Devices that efficiently use light emitted from the element have been developed.

  For example, in Patent Document 1, an LED or a light emitting element as the light source is mounted on a flexible substrate (FPC), and the curved FPC is placed in a notch on one side wall of the housing frame for positioning the LED. What is inserted and engaged at a predetermined position is shown.

  In Patent Document 2, as shown in FIG. 8, there is one in which an FPC 50 extending to the bottom of the frame body 40 is folded and fixed to the side wall of the light guide plate 60. In this specification, many embodiments for positioning the light emitting element 45 arranged on the FPC are shown. In the embodiment of FIGS. 8A and 8B, the tip of the overhanging portion 52 of the FPC 50 is shown. Is provided with a convex end portion 53, and the convex end portion 53 is fitted into the concave portion 56 formed on the side surface of the light guide plate 60, and the guide portion 57 of the light guide plate 60 is applied to the shoulder portion of the overhang portion 52 of the FPC 50 for bonding. A method of attaching and fixing the FPC 50 to the light guide plate 60 via the member 58 is disclosed.

  As another form, as shown in FIG. 9 (a), a concave portion 62 as an insertion space for the light emitting element 45 and a positioning projection 63 are provided on the side surface of the light guide plate 60. A hole 64 that opposes the protrusion 63 is provided. The end portion of the FPC 50 arranged at the bottom of the frame body is folded back to the side surface of the light guide plate 60, and the FPC hole 64 is fitted into the projection 63 of the light guide plate to be welded. The protruding portion of the FPC 50 can be accurately fixed to the side surface of the light guide plate 60 by being arranged accurately. In this case, the light emitting element on the overhanging portion is housed in the concave portion 62 of the light guide plate and emits light toward the light guide plate 60.

  Further, as shown in FIG. 9 (b), a slit-shaped opening is provided in the side portion of the frame body 40 to form a light emitting element storage portion 65, and an overhanging portion 66 of the FPC 50 is inserted into the storage portion. A method is also disclosed in which the tip is pulled out from the opening, and a projection 68 is inserted into the hole 67 of the overhanging portion and welded. According to this method, the overhanging portion 66 is fixed to the frame body 40, and the light emitting element 45 can be accurately positioned in the light emitting element storage portion 65.

  In addition, in Patent Document 3, three pins are formed on the end surface of the transparent light guide plate, and the LED module is attached to the transparent light guide plate by fitting with holes formed in the LED module corresponding to the pins. In some cases, the light guide plate is fitted into the outer frame, the transparent light guide plate is fixed to the hook of the outer frame, the LED module is accommodated in the recess, and the LED module is pressed against the light guide plate with a spring.

  Further, in Patent Document 4, as shown in FIG. 10, in a mobile phone or the like, a light guide plate 60 is fixed between the portable keyboard 70 and the printed circuit board 72 and fixed inside the exterior body, and is placed on the printed circuit board. Some LEDs 75 are configured to illuminate the entire area of the portable keyboard 70 and the liquid crystal display panel 80 from the back side.

  In the backlight unit used for this cellular phone or the like, the light guide plate 60 and the printed circuit board 72 are directly connected without providing a frame.

  Further, as shown in FIG. 7A, in a conventional backlight keyboard unit that irradiates the light of the light emitting element 45 toward the side surface of the light guide plate 60, a recess for inserting the light emitting element 45 into the light guide plate 60. 42 is formed, and a method of positioning the FPC 50 to which the light emitting element 45 (LED) is attached to the light guide plate 60 is used.

  In this case, as shown in FIG. 7 (b), first, the FPC 50 and the reflection sheet 44 are positioned using the positioning pin A, and then attached, and further, the reflection sheet 44 to which the FPC 50 is fixed. Is disposed on the back surface of the light guide plate 60, and the light emitting element 45 is illuminated from the side surface, so that the light guide plate 60 and the reflection sheet 44 are positioned via the positioning pin B.

JP 2005-267881 A JP 2003-90993 A JP 2002-324423 A Japanese Patent Laid-Open No. Hei 6-20217

In the above Patent Documents 1 and 2, since a frame body that supports the light guide plate is used and the FPC is positioned by being regulated by the frame body, the light guide plate and the FPC are not directly in contact and fixed. The positional relationship between the light source and the light guide plate increases the processing accuracy of each component, and the accuracy cannot be maintained.
In Patent Document 3, the LED module is attached to the transparent light guide plate with three pins. However, when the light guide plate is thin (for example, 0.4 mm thick), the pins cannot be raised. Even if it is difficult and can be erected, the LED module cannot be mounted due to insufficient strength.
Moreover, in patent document 4, since LED75 is arrange | positioned at the bottom part side of the light-guide plate 60, the thickness reduction is restrict | limited by the height of LED. Further, since the LED 75 is arranged in a recessed space provided in the light guide plate 60, the positioning of the printed circuit board 72 with respect to the light guide plate 60 is not certain.
Further, in the conventional backlight keyboard unit, in this method, the FPC mounting position error of the light emitting element 45, the mounting error at the positioning pin A, and the mounting error at the positioning pin B are integrated, and the target dimension is obtained. The actual dimensional accuracy is ± 0.5 mm compared to the accuracy of ± 0.2 mm, and the variation in positional accuracy between the light guide plate and the light emitting element increases, resulting in variations in the amount of light emitted from the light guide plate (non-uniform luminance). It was.

  The present invention has been made in view of such circumstances, and provides a light source positioning structure for a keyboard unit for a backlight that achieves improved LED positioning accuracy by abutting a light guide plate against a flexible substrate. Objective.

In order to solve the above-described object, the present invention includes a light guide plate for backlight, at least one point light source disposed on a light incident surface of the light guide plate, and a flexible substrate on which the point light source is mounted. In the light source positioning structure of the keyboard unit for backlight,
The light guide plate has a plurality of protrusions and recesses on an end surface on the light incident surface side, and the flexible substrate has a plurality of slits arranged corresponding to the plurality of protrusions, and between the slits or in parallel with the slits. Including the point light source disposed, and an adhesive member formed on at least one portion where the light guide plate overlaps the flexible substrate,
Each of the protrusions is inserted into the slit provided on the flexible substrate, the peripheral edge of the slit is abutted against the outer surface of the base end of the protrusion, and the point light source The light guide plate is fixed to the flexible substrate so that the distance to the facing surface is an appropriate distance defined in a minimum tolerance range.

  According to this configuration, since the protrusion of the light guide plate is inserted into the slit of the flexible substrate and the peripheral edge of the slit is abutted against the outer surface of the base end portion of the protrusion, the gap dimension between the light guide plate and the point light source is appropriately set. And can be set easily.

  Moreover, since the light guide plate and the flexible substrate are directly fixed via an adhesive member, the positioning accuracy of the point light source with respect to the light guide plate is improved, and the luminance of the backlight illumination can be made uniform.

  In a preferred embodiment of the present invention, an appropriate distance between the light guide plate and the point light source is 0.2 to 0.5 mm, and a minimum tolerance range is ± 0.15 mm. . Thereby, the amount of light incident on the light incident surface of the light guide plate from the light emitting surface of the point light source in the backlight keyboard unit can be made uniform.

In another configuration, the recess of the light guide plate is formed with a notch for receiving the point light source.
As a result, by arranging all the point light sources arranged on the flexible board behind the slit line, the rise of the flexible board due to the fitting of the slit and the protrusion is not directly affected by the point light source, and it is easy In addition, the gap between the point light source of the flexible substrate and the end face of the light guide plate can be accurately maintained.

The protrusion of the light guide plate has a pair of legs adapted to the slit length, and has a recess in which a point light source is disposed between the legs.
Thereby, the point light source mounted on the flexible substrate is not affected by the rise of the flexible substrate due to the fitting of the slit and the projection, and the peripheral edge of the slit abuts against the outer surface of the base end portion of the projection. The gap between the point light source on the flexible substrate and the end face of the light guide plate can be accurately maintained.

  Since the light guide plate is made by die cutting, it is easy to form such protrusions and recesses, and the light source of the backlight keyboard unit has various forms such as the number of point light sources and the arrangement of other parts. Corresponding to the positioning structure, the end face shape of the light guide plate can be easily manufactured.

  In addition, the light guide plate and the flexible substrate can be connected directly or via an adhesive member such as a double-sided tape with a reflection sheet sandwiched between them, and the light guide plate and the flexible substrate can be bonded or bonded to the reflection plate. It is easy, and the overlapping height between the light guide plate and the flexible substrate can be easily controlled.

  In the present invention, a projection formed on the light guide plate is inserted into and abutted into the slit on the flexible substrate, so that the point light source (LED) on the flexible substrate and the end surface (light incident surface) of the light guide plate can be easily formed. The gap can be kept to a minimum deviation tolerance.

It is a disassembled schematic block diagram of the keyboard unit which concerns on this invention. 1A and 1B show a first embodiment of the present invention, in which FIG. 2A is a partial view of a protruding portion of a light guide plate, and FIG. 2B is a partial view showing a shape of a slit provided in a flexible substrate. It is a perspective view which shows the state which inserts the protrusion of a light-guide plate in the slit provided in the flexible substrate which concerns on this invention. It is state sectional drawing after protrusion insertion which concerns on this invention. The gap between the point light source and the light guide plate according to the present invention is shown, (a) is a state diagram in which the flexible substrate and the light guide plate are directly connected, (b) is between the flexible substrate and the light guide plate. FIG. 6 is a state diagram in which a reflection sheet is sandwiched and bonded. The 2nd Embodiment concerning this invention is shown, (a) is a decomposition | disassembly schematic block diagram of the unit similar to FIG. 1, (b) is a fragmentary perspective view which shows the state which inserted the protrusion in the flexible substrate. . The positional relationship between a point light source and a light guide plate arranged on a flexible substrate in a conventional example is shown, (a) is a schematic diagram showing a state in which a concave portion is provided in the light guide plate corresponding to the point light source, (b) is a side sectional view showing a state in which two positioning pins are provided for positioning the flexible substrate and the light guide plate. The engagement relationship of the light guide plate and FPC by a prior art example is shown, (a) is a perspective view, (b) is a side view. The engagement relationship of the protrusion of the light-guide plate and the hole of FPC by a prior art example is shown, (a) is a perspective view, (b) is a sectional side view which shows another example. It is sectional drawing which shows arrangement | positioning of LED and the light-guide plate provided on the printed circuit board of a prior art example.

Embodiments of a light source positioning structure for a backlight keyboard unit according to the present invention will be described below with reference to the drawings.
1 to 5 show a first embodiment of a light source positioning structure of the present invention, and FIG. 1 is an exploded schematic configuration diagram of a keyboard unit.

FIG. 2 is a partial view showing a protrusion shape of the light guide plate and a slit shape of the flexible substrate for fitting the light guide plate and the flexible substrate. FIG. 3 is a perspective view showing a state in which the projection of the light guide plate is inserted into the slit provided in the flexible substrate, and FIG. 4 is a sectional view of the state after the insertion.
FIG. 5 shows a gap between the point light source and the light guide plate, (a) is a state diagram in which the flexible substrate and the light guide plate are directly connected, and (b) is a diagram between the flexible substrate and the light guide plate. FIG. 6 is a state diagram in which a reflection sheet is sandwiched and bonded.

  1 to 3, a keyboard unit 1 according to the present invention includes, from above, a keyboard assembly 2, a masking sheet 3, a lead cap 2a and a stabilizer (not shown) that slides the key cap up and down. The optical plate 4, the flexible substrate 5, and the reflection sheet 6 are combined.

  The light source positioning structure of the present invention positions the point light source (LED 7) with respect to the light guide plate 4 by directly superposing and fixing the light guide plate 4 and the flexible substrate 5, and the light guide plate 4 and the flexible substrate 5 are flexible. In this method, the substrate 5 is directly fitted.

As shown in FIGS. 1 and 2, the light guide plate 4 has a plurality of protrusions 10 and a plurality of recesses 12 and 12 ′ formed on the end surface on the light incident surface side. These recesses include a recess 12 provided in the projection 10 forming the pair of leg portions 11, 11 and a recess 12 ′ disposed between the projection and the projection. Further, in a recess 12 ′ formed between the protrusions 10, the LED 7 and the register 8 (hereinafter referred to as LED 7) disposed in the FPC 5 correspond to the LED 7 and the register 8 (hereinafter referred to as “LED 7”). A notch 14 is provided.
Accordingly, the protrusion 10, the recesses 12, 12 ', and the notches 14 are disposed on the end face of the light guide plate 4 in FIG.

  On the other hand, a plurality of slits 15 arranged in a row are arranged on the FPC in FIG. 1, and LEDs 7 and the like are arranged in the number of about 3 to 10 located behind the slits 15. The LED 7 is provided in parallel with the slit 15 or between the slits. Moreover, the number of the slits 15 is arrange | positioned at the both sides and center part of the flexible substrate 5, and the number is arrange | positioned 3-4 pieces.

The shape of the protrusion 10 inserted into the slit 15 is preferably a U shape having a pair of legs 11 and 11 corresponding to the length of the slit 15 as shown in FIG. A recess 12 is formed between the parts, and the LED 7 and the like located behind the slit 15 are accommodated in this space. For this reason, the end surface 12 a of the recess 12 has a shape that is recessed further to the back than the proximal end portion outer surface 10 a of the protrusion 10.
In addition, the notch 14 of the recess 12 ′ has a shape that is recessed deeper than the base end outer surface 10 a of the protrusion 10, and the end surface 12 a and the notch 14 have the same depth dimension.

The length L of the slit 15 is about 1 mm larger than the width M of the protrusion 10 and is sufficiently longer than the width a of the LED 7 or the like. The slit width W is 0.5 mm with respect to the thickness of the light guide plate of 0.4 mm. Further, the width N of the recess 12 provided in the pair of leg portions 11 of the protrusion 10 is a distance that allows the LED 7 and the like to be sufficiently accommodated.
A double-sided tape 20 as an adhesive member is attached around the rear end of the flexible substrate 5.

  As shown in FIG. 3, when the protrusion 10 having the pair of legs 11, 11 is inserted into the slit 15 of the flexible substrate 5, the insertion of the protrusion 10 causes the flexible substrate 5 in front of the slit to rise. Since the LED 7 and the like are behind the slit, they are not directly subjected to a load due to the rising of the flexible substrate 5. For this reason, dangers, such as position shift of LED7 grade | etc., And disconnection of a wiring part, do not arise.

  The fitting between the slit 15 and the projection 10 is such that the outer surface 10a of the projection base end abuts against the peripheral portion 15a of the slit 15, whereby the coupling position between the light guide plate 4 and the flexible substrate 5 is determined. As shown to (a), the flexible substrate 5 is directly fixed to the light-guide plate 4 through the double-sided tape 20 affixed on the upper surface of the edge part of the flexible substrate 5. As shown in FIG.

As a result, the gap d between the light emitting surface 7a of the LED 7 and the end surface of the light guide plate 4 is determined as the distance from the slit position to the end surface position of the light guide plate 4, so that the gap deviation tolerance between the LED 7 and the light guide plate end surface is It can be obtained by the following calculation formula.

(Gap deviation tolerance) = LED mounting accuracy (± 0.1mm)
+ Light guide plate and flexible substrate positioning accuracy (± 0.05mm)
= ± 0.15mm

  In this way, in the present invention, the gap deviation tolerance range is maintained at ± 0.15 mm so that the luminance of the backlight light is uniform, and the gap between the LED and the end face of the light guide plate is within the proper range 0. It can prescribe | regulate to 2-0.5 mm.

Further, after the protrusion 10 of the light guide plate 4 is inserted into the slit 15, the affixing operation between the bottom of the light guide plate and the flexible substrate 5 is fixed with the double-sided tape 20. In this case, as shown in FIG. By using the double-sided tape 20 disposed between the flexible substrate 5 and the light guide plate 4, the reflection sheet 6 positioned behind the flexible substrate 5 is fixed at the same time.
As another example, the flexible substrate 5 may be extended longer and the reflective sheet 6 may be fixed between the flexible substrate 5 and the light guide plate 4 using the double-sided tape 20.

In the light source positioning structure of the keyboard unit for backlight of the present invention, the light guide plate is abutted against the flexible substrate to realize the positioning accuracy of the LED, and by the combination of the flexible substrate, the light guide plate, the reflective sheet, and the double-sided tape, The overlapping height of the light guide plate 4 and the flexible substrate 5 can be defined, and each material is very thin, and the total height can be adjusted according to the standard of the keyboard unit.
Moreover, since the adhesive member that fixes the flexible substrate to the light guide plate is a double-sided tape, it is easy to bond the light guide plate and the flexible substrate by overlapping them, and the backlight keyboard unit can be made thin at the same time. Can do.

Next, FIG. 6 shows a second embodiment of the present invention, (a) is an exploded schematic configuration diagram of a unit similar to FIG. 1, and FIG. 6 (b) is a fitting of a slit and a protrusion. FIG.
In the second embodiment, the protrusion 10 ′ formed on the light guide plate 4 ′ is trapezoidal or rectangular having a chamfered portion at the tip, and the LED 7 is further provided in the recess 12 ′ formed between these protrusions. A notch 14 is provided for storing the like.

  In addition, the slits 15 are arranged at both ends and the central part as in FIG. 1, and the elements such as the LEDs 7 are arranged behind the line of the slits 15 and are recesses formed between the projections 10 ′ and 10 ′. 12 is housed in a notch 14 provided in the inside.

  FIG. 6 (b) is a perspective view showing the fitting between the slit and the protrusion, but the front portion of the flexible substrate 5 ′ into which the protrusion 10 ′ is inserted is swelled and stress is applied. By arranging the LEDs 7 and the like behind the 15 lines and storing them in the cutouts 14, it is possible to avoid the rise of the flexible substrate 5 ′.

  In the embodiment described above, in the present invention, the thickness of the light guide plate inserted into the slit is about 0.4 mm, but in the future, it can be further reduced, and the flexible substrate at that time This can be dealt with by narrowing the slit width appropriately. And such a light-guide plate is manufactured by die-cutting, can process a shape of a processus | protrusion and a recessed part precisely, and will also reduce manufacturing cost.

DESCRIPTION OF SYMBOLS 1 Keyboard unit 2 Keyboard assembly 4, 4 'Light guide plate 5, 5' Flexible substrate 6 Reflective sheet 7 LED
10, 10 'projection 12, 12' recess 14 notch 15 slit 20 double-sided tape

Claims (4)

A light guide plate for backlight;
At least one point light source disposed on the light incident surface of the light guide plate;
In the light source positioning structure of the keyboard unit for backlight including the flexible substrate on which the point light source is mounted,
The light guide plate has a plurality of protrusions and recesses on the end surface on the light incident surface side,
The flexible substrate has a plurality of slits arranged corresponding to the plurality of protrusions,
The point light source disposed between or parallel to the slits;
An adhesive member formed on at least one portion where the flexible substrate and the light guide plate overlap,
Each of the protrusions is inserted into the slit provided in the flexible substrate,
The peripheral edge of the slit is abutted against the outer surface of the base end of the protrusion,
The light guide plate is fixed to the flexible substrate so that the distance from the light incident surface of the light guide plate to the opposing surface of the point light source is an appropriate distance defined in a minimum tolerance range. Light source positioning structure of the keyboard unit for backlight.   2. The light source positioning structure for a keyboard unit for backlight according to claim 1, wherein the appropriate distance is 0.2 to 0.5 mm, and a minimum tolerance range is ± 0.15 mm.   3. A light source positioning structure for a backlight keyboard unit according to claim 1, wherein the recess of the light guide plate is formed with a notch for receiving the point light source.   4. The projection according to claim 1, wherein the projection of the light guide plate has a pair of legs adapted to the slit length, and a recess in which the point light source is disposed between the legs. A light source positioning structure of the keyboard unit for backlight according to claim 1.