KR100900499B1 - Luminous apparatus of keypad assembly for mobile communication terminal and kepad assembly having the luminous apparatus - Google Patents

Abstract

The present invention relates to a light emitting device of a keypad assembly for a mobile communication terminal, and more particularly, the light emitting device of the keypad assembly for a mobile communication terminal is provided in the keypad assembly of the mobile communication terminal to emit light with a keytop provided with a plurality of key buttons. In doing that,

Light transmitting sheet; A light source for injecting light into the light guide sheet; And a plurality of reflection patterns provided on a lower surface of the light guide sheet to reflect light passing through the light guide sheet toward a key button provided on an upper side of the light guide sheet. Each of the patterns is printed on the back surface of the light guide sheet in the form of letters so that a user can recognize a plurality of key buttons separately from each other.

Light guide sheet, reflection pattern, light source, text

Description

Luminous apparatus of keypad assembly for mobile communication terminal and kepad assembly having the luminous apparatus

The present invention relates to a light emitting device of a keypad assembly for a mobile communication terminal and a keypad assembly for a mobile communication terminal provided with the light emitting device. A light emitting device for a keypad assembly for a mobile communication and a keypad assembly for a mobile communication terminal provided with the light emitting device.

Mobile communication terminals have been widely used to date because they are easy to carry and have various functions in addition to wireless communication. 1 illustrates an exploded perspective view of a mobile communication terminal according to the prior art, and the mobile communication terminal 100 includes a main body 110 and a folder 120. The main body 110 includes an upper frame 111 and a lower frame 112, and a keypad assembly 130, a light emitting device 140, and a printed circuit between the upper frame 111 and the lower frame 112. The substrate 150 is provided in a stacked structure.

The light emitting device 140 is for illuminating a plurality of key buttons, there is a use of an EL sheet as such a light emitting device, a specific appearance is shown in FIG.

The key top 131 and the key base 133 are provided above the light emitting device 140. A key button 132 is provided on the key top 131, and a plurality of protrusions 134 are provided on the rear surface of the key base 133. The printed circuit board 150 is provided below the light emitting device 140. The dome switch 152 surrounding the plurality of contacts 151 and the plurality of contacts 151 and the dome switch 152 are fixed to the printed circuit board 145 on the upper surface of the printed circuit board 150. A dome sheet top tape 153 is provided.

In this conventional technique, when power is applied from one side of an EL sheet to illuminate a key button, charging and discharging are repeated and light is generated inside the EL sheet, and the generated light illuminates a plurality of key buttons. However, such an EL sheet has to generate high voltage AC current, so it is not only difficult to consume power, manufacturing cost, manufacturing method, etc. Because it illuminates, there are many disadvantages of unnecessary light consumption.

As shown in FIG. 3, a light emitting device 140 using a light source 141 and a light guide sheet 142 made of LEDs is used to overcome these disadvantages. In the light emitting device using the light source 141 and the light guide sheet 142 illustrated in FIG. 3, when light generated from the light source 141 provided at one edge of the light guide sheet 142 is incident into the light guide sheet 142, the light incident device is incident. The light passes through the total reflection at the upper and lower surfaces of the light guide sheet 142.

In this case, a reflective pattern 143 that diffusely reflects light generated from the light source 141 is provided on the rear surface of the light guide sheet 142. The reflective pattern 143 is a discontinuous groove formed on the rear surface, and the light in contact with the discontinuous groove is diffusely reflected without being totally reflected to enter the upper surface side of the light guide sheet facing the reflective pattern to illuminate the key button. Unlike the EL sheet, the light emitting device does not require high-voltage AC current, so there is no difficulty in power consumption, manufacturing cost, or manufacturing method. If the reflective pattern is printed only on the required part, it only illuminates the desired key button so that unnecessary light consumption is consumed. There is no advantage.

The conventional light emitting device has a plurality of reflection patterns 143 corresponding to the key button 132, each of the reflection pattern 143 is in the form of a dot. In this case, the reflective pattern 143 adjacent to the light source 141 provides a small number of dots, and the reflective pattern 143 far from the light source 141 provides a large number of dots, and a detailed shape thereof is illustrated in FIG. 3. .

The reason for varying the number of dots according to the distance from the light source is that the portion close to the light source 141 has sufficient brightness even when a small amount of light is reflected due to the intensity of the light, but is far from the light source 141. This is because a large number of light is reflected from the reflective pattern 143 close to the light source 141, so that the light intensity is weak so that a large number of dots must be provided to reflect sufficient light.

Meanwhile, the light emitted from the light emitting device 140 passes through the key top 131 and the key base 133. However, in order for the light to pass through both the key top 131 and the key base 133, not only the intensity of the light emitted from the light emitting device 140 needs to be strong, but also the overall thickness of the assembly of the keypad assembly becomes thicker. It is a factor that hinders slimming.

In order to solve this problem, there is a plug-in keypad assembly of FIG. 4 in which the key base 133 is removed from the prior art illustrated in FIG. 3 and the printed circuit board 150 is replaced with a flexible one.

4 shows this plug-in type keypad assembly. The keypad assembly includes a light emitting device 140 below the key top 131 and a flexible printed circuit board below the light emitting device. The bottom surface of the flexible printed circuit board is provided with a contact 151, a dome switch 152 surrounding the contact, and a dome sheet top tape 153 for fixing the dome switch to the flexible printed circuit board. As such, the keypad assembly of FIG. 4 may reduce the thickness of the entire mobile communication terminal as the key base is removed.

On the other hand, if the key base is removed from the keypad assembly, the overall structural rigidity decreases and the user's feeling of click tends to be impaired. However, in the technique illustrated in FIG. 4, the flexible printed circuit board is replaced with the light emitting device instead of the key base. Since it is provided on the lower side, the user can feel the click feeling when the user presses the key button as it can contribute to the slimming of the overall mobile communication terminal.

Meanwhile, FIG. 5 illustrates a light guide sheet 142 of the related art shown in FIG. 4, and a plurality of reflective patterns 143 are formed at positions corresponding to the key buttons. As described in the description of FIG. 3, the reflective pattern 143 has a small number of dots printed near the light source, while a large number of dots are printed far from the light source.

4 and 5 also have the following problems.

Since the light emitting device is provided directly under the key top, when the user looks at the key top from the top of the key top, the dots of each reflection pattern provided under the key top are visible.

That is, in the prior art in which the key top and the key base are provided together, the key top and the key base have sufficient thickness, so that the dot provided on the lower side is not visible and the illumination is simply soft and uniform, but in the technology in which the key top is removed, the thickness is thin. (Approximately 50-70% level) The dot form is seen as it is, there is a problem that does not give a good image to the user.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a light emitting device of a keypad assembly for a mobile communication terminal, which contributes to the overall slimming of the mobile communication terminal and gives a good illumination image to the user.

The light emitting device of the keypad assembly for a mobile communication terminal of the present invention for achieving the above object is provided in the keypad assembly of the mobile communication terminal to emit light with a keytop provided with a plurality of key buttons,

Light transmitting sheet; A light source for injecting light into the light guide sheet; And a plurality of reflection patterns provided on a lower surface of the light guide sheet and reflecting light passing through the light guide sheet toward a key button provided on an upper side of the light guide sheet. Each of the plurality of reflection patterns is printed on the back surface of the light guide sheet in the form of letters so that a user can recognize the plurality of key buttons separately from each other.

In the light emitting device, each of the reflective patterns is preferably printed on the rear surface of the light guide sheet further including a number.

In the light emitting device, each of the reflective patterns is preferably printed on the rear surface of the light guide sheet further including a closed curve surrounding the letters and numbers.

In the light emitting device, the reflective pattern is preferably composed of a translucent synthetic resin and a plurality of reflective particles contained in the synthetic resin.

In the light emitting device, the reflective particles are preferably a fluorescent pigment for changing the wavelength band of light incident on the light guide sheet.

In the light emitting device, the fluorescent pigment is preferably made of sulfides of zinc, strontium and barium.

In the light emitting device of the keypad assembly for a mobile communication terminal of the present invention as described above, the reflection pattern is printed on the back surface of the light guide sheet in the form of letters or numbers, so that even if the keypad assembly is slim, the dots are not visible to the user, thereby providing a good image. Can be given.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

6 is a view illustrating a light guide sheet and a light source of the light emitting device according to the present embodiment, FIG. 7 is a perspective view of FIG. 6, FIG. 8 shows a keypad assembly provided with the light emitting device of FIG. 7, and FIG. 9 is FIG. 8. A view showing a state in which light is emitted through the light emitting device.

The light emitting device 40 of the keypad assembly for a mobile communication terminal according to the present embodiment is provided in the keypad assembly of the mobile communication terminal to emit light to the key top 31 having a plurality of key buttons 32.

The light emitting device includes a light guide sheet 41, a light source 42, and a reflective pattern 43.

The light guide sheet 41 is preferably made of a light-transmitting polycarbonate (PC) or polyurethane (Polyurethane: PU), but is transparent to an acrylic resin such as polymethyl methacrylate or methacryl-styrene copolymer. Anything excellent can be used.

On the other hand, in the light guide sheet 41, when light is incident from the light source 42, the light causes total reflection on the upper and lower surfaces of the light guide sheet 41. The total reflection here means reflection with 100% reflectance. Optically, when light travels from a dense medium to a small medium, total reflection occurs when light is incident at an angle greater than the critical angle. That is, light incident from the light source 42 to the light guide sheet 41 is transferred from the light guide sheet 41 (a dense medium having a large refractive index) to air (small medium having a small refractive index) through the upper or lower surface of the light guide sheet 41. When incident, when the incident angle is greater than or equal to the critical angle, total reflection occurs. In particular, such total reflection easily occurs as the difference in refractive index is large. Air has the lowest refractive index, making it easy to totally reflect any contact with any medium.

Meanwhile, in the present embodiment, light incident on the light source 42 is totally reflected on the upper and lower surfaces of the light guide sheet 20 (that is, incident on the upper and lower surfaces of the light guide sheet larger than the critical angle at which total reflection can occur). The thickness of the light guide sheet 41 is designed to be sufficiently small, or is designed to sufficiently maintain the separation distance between the light source 42 and the light guide sheet 41.

The light source 42 is disposed outside one side edge of the light guide sheet 41 to inject light into the light guide sheet 41. The separation distance between the light source 42 and the light guide sheet 41 has a sufficient separation distance such that light incident on the light guide sheet 41 may cause total reflection between the upper and lower surfaces.

The light source 42 emits light when electricity is supplied, and a light emitting diode or the like may be used. The light source 42 is provided in the keypad assembly to prevent the light from leaking to the peripheral portion to reduce the overall failure rate, and does not require a separate light source.

The reflection pattern 43 allows the light traveling through the light guide sheet 41 to be reflected toward the key button 32. A plurality of such reflective patterns 43 are provided to correspond to the key buttons. Among the plurality of reflection patterns 43, each reflection pattern 43 is printed on the back surface of the light guide sheet in the form of letters, numbers, and closed curves surrounding the letters and numbers. However, in addition to the various figures, symbols, etc. may be further printed on the back of each light guide sheet.

The reflective pattern 43 is provided on the lower surface of the light guide sheet 41 in a conventional printing method. Specifically, screen printing, offset printing, pad printing, or the like may be used.

On the other hand, each of the reflective patterns 43 is composed of a resin 44 and the reflective particles (45). The resin 44 is light-transmissive, and the liquid containing the reflective particles 45 is hardened. At the time of printing, a volatile solvent is applied to the lower surface of the light guide sheet 41 together with the resin 44 and the reflective particles 45, but at the time of drying after printing, the solvent is volatilized 100% so that the solid does not remain in the spun pattern. The reflective particles 45, which are powders, are positioned between the resins 44.

The reflective particles 45 have good reflecting properties and use a light-emitting pigment for printing of fine powder made of a phosphor, and may use a white pigment that reflects the light incident from the light-emitting pigment as it is, and varies the wavelength band of the incident light. Preference is given to using fluorescent pigments which are allowed to emit in color. Such fluorescent pigments are preferably made of sulfides of zinc, stromium, and barium to easily express colors, but various kinds of materials may be used.

When light incident on the light guide sheet 41 reaches the reflection pattern 43, the light is not reflected but is incident on the resin 44. The incident light is diffusely reflected at various angles in contact with the surface of the reflective particles 45 as shown in FIG. 9.

Reference numerals 31, 32, 50, 51, 52, and 53 denote key tops, key buttons, flexible printed circuit boards, contacts, dome switches, and dome sheet top tapes, respectively.

The key top 31 is provided above the light emitting device 40. The flexible printed circuit board 50 is provided below the light emitting device 40, and a plurality of flexible printed circuit boards 50 are provided on the bottom surface of the flexible printed circuit board 50 to cover the plurality of contacts 51 and the respective contacts 51. The dome switch 52 and the dome sheet top tape 53 for fixing the dome switch 52 to the flexible printed circuit board 50 are provided.

The light emitting device of the mobile communication terminal according to the present embodiment having such a configuration functions as follows.

When the user needs to illuminate to open a folder or press a predetermined key button, electricity is applied to the light source 42, and thus light is generated from the light source 42. Light generated from the light source 42 is incident on the adjacent light guide sheet 41. The light incident on the light guide sheet 41 proceeds while totally reflecting between the upper and lower surfaces of the light guide sheet 41. When the light comes into contact with the reflective pattern 43 provided on the rear surface of the light guide sheet 41, the key top 31 is diffusely reflected. Is released to the side. Specifically, the light incident on the reflective pattern 43 passes through the transparent resin 44 and comes into contact with the surface of the reflective particles 45, and is reflected at a predetermined angle from the surface of the reflective particles 45. The reflected light is moved to the side of the key top 31 provided above. In this case, when the reflective particles 45 are made of fluorescent pigments, the light is reflected in various colors instead of white light.

The light emitting device of the mobile communication terminal according to the present embodiment having such a function has the following effects.

First, in the prior art illustrated in FIG. 4, since each of the reflective patterns 143 is formed in the form of dots, when the light emitting device 140 is provided on the rear surface of the thin key top 131, the user may have a dot-shaped reflective pattern ( 143), as it is, gave bad perception. In addition, light is not reflected in the dot-dot area, so that uniform illumination is not achieved. In other words, the light is directly above the dot and the light is not reflected between the dots, so it is dark, so that the illumination of the entire key button is uneven. On the contrary, in the present embodiment, since each reflection pattern 43 is in the form of numbers, letters, and other symbols that can be recognized by the user, the user does not give a bad image to the user. On the contrary, the reflected light is reflected in the form of letters, numbers, and other shapes so that the letters are recognized more clearly.

In addition, in the present embodiment, since the reflective pattern 43 is printed only with the required alphanumeric characters, there is no unnecessary light consumption. That is, in the prior art illustrated in FIG. 4, since a plurality of dots are provided in each reflective pattern 143 provided below the key button 132 to illuminate one key button 132, unnecessary light consumption is consumed. (I.e., not only the part where the letter or number part is provided in the key button but also the whole key button). Due to this unnecessary consumption of light, a number of dots had to be prepared far from the light source. On the contrary, in the present embodiment, since the reflection pattern reflects light only in the form of letters or numbers which are necessary, the amount of light reflected from the reflection pattern closer to the light source is less, and the light intensity is increased even if it is far from the light source. It is not attenuated and does not require a technique for increasing light reflection separately. This reduces the overall consumption of light has the advantage of reducing the amount of electricity supplied to the light source.

The keypad assembly 10 of the mobile communication terminal according to the present invention can be modified as follows.

First, the light emitting device according to the present invention may be applied to a keypad assembly having various stacking structures in addition to the slim keypad assembly described above. That is, it can be applied to a keypad assembly provided with a general key top and key base.

In addition, in the light emitting device according to the present invention, various kinds of materials may be used as the reflective particles in addition to the white pigment or the fluorescent pigment. That is, anything that reflects light incident on the light guide sheet can be used.

In addition, the reflective pattern according to the present invention can be applied in various forms in addition to the resin and the reflective particles. That is, any thing can be used as long as it is provided on the back surface of the light guide sheet to reflect the light incident from the light source. However, even in this case, the reflective pattern should be provided on the back surface of the light guide sheet in the form of letters or numbers.

In addition, the reflective pattern according to the present invention may allow the light of different colors to be emitted from letters or numbers provided in the respective reflective patterns. That is, if the types of fluorescent pigments are printed differently so that letters or numbers provided in the respective reflection patterns may emit light of each other, various colors may be realized within one key button. That is, in FIG. 6, "2" may be blue, and abc may be red. On the contrary, in the prior art, it is difficult to implement various colors of light.

Although the present invention has been described in detail with reference to embodiments and various modifications, the present invention is not necessarily limited to these embodiments and modifications, and various modifications may be made without departing from the spirit of the present invention. Can be.

1 is an exploded perspective view of a mobile communication terminal according to the prior art.

2 is a cross-sectional view of the mobile communication terminal of FIG.

3 is a cross-sectional view of a mobile communication terminal according to another prior art.

4 is a cross-sectional view of another mobile communication terminal according to the related art.

5 is a plan view of a light guide sheet of the light emitting device of FIG. 4;

6 is a plan view of a light guide sheet of a light emitting device for a mobile communication terminal according to an embodiment of the present invention;

7 is a perspective view of FIG. 7;

8 is a cross-sectional view of a mobile communication terminal having the light guide sheet of FIG. 6 provided therein.

9 is an enlarged view of some main components of FIG. 8;

<Detailed Description of Drawings>

31 ... Keytop 32 ... Key Button

40 ... light emitting device 41 ... light guide sheet

42 ... light source 43 ... reflection pattern

44 ... Resin 45 ... Reflected Particles

50 ... Flexible Printed Circuit Board 51 .. Contacts

52 ... Dome Switch 53 ... Dome Seat Top Tape

Claims (6)

Is provided in the keypad assembly of the mobile terminal to emit light to the key top provided with a plurality of key buttons, Light transmitting sheet; A light source for injecting light into the light guide sheet; And a plurality of reflection patterns provided on a lower surface of the light guide sheet and reflecting light passing through the light guide sheet toward a key button provided on an upper side of the light guide sheet. Each of the plurality of reflection patterns, Light emitting device of a keypad assembly for a mobile communication terminal, characterized in that the user is printed on the back of the light guide sheet in the form of a character so that the user can recognize a plurality of key buttons. The method of claim 1, Each of the reflective patterns is a light emitting device of a keypad assembly for a mobile communication terminal, characterized in that the printed on the back of the light guide sheet further comprises a number form. The method of claim 2, Each of the reflective patterns further includes a form of a closed curve surrounding the letters and numbers, the light emitting device of the keypad assembly for a mobile communication terminal, characterized in that printed on the back of the light guide sheet. The light emitting device of a keypad assembly for a mobile communication terminal according to any one of claims 1 to 3, wherein the reflective pattern is composed of a transparent synthetic resin and a plurality of reflective particles contained in the synthetic resin. The method of claim 4, wherein The reflective particle is a light emitting device of a keypad assembly for a mobile communication terminal, characterized in that the fluorescent pigment for changing the wavelength band of light incident on the light guide sheet. The method of claim 5, The fluorescent pigment is a light emitting device of the keypad assembly for a mobile communication terminal, characterized in that consisting of sulfides of zinc, strontium, barium.

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