JP2011054573A - Keyswitch structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a keyswitch structure which elongates illumination life and maintains uniform and good illumination state at a relatively low cost. <P>SOLUTION: A keytop 11 is formed from a transmitting member, with a light-transmitting offprint character 11c being formed. A back plate 17 of transparent member is arranged at the lower part of a membrane sheet 16 which is light-transmitting and has a contact point. A printed wiring board 19 mounting an LED 20 is provided at the lower part of the back plate 17. The LED 20 is arranged directly under the offprint character 11c at the keytop 11. Roughs 16h and 17c are formed on the surface of the membrane sheet 16 and that of the back plate 17. When the LED 20 lights, the light is diffused as it passes the back plate 17 and the membrane sheet 16, to illuminate the offprint character 11c of the keytop 11 after passing through a rink member or the like under the keytop 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a key switch structure of a keyboard used as an input device in an information processing device, a measuring device, a medical device, and the like, and more particularly to a key switch structure having an illumination function that can ensure good operability even in a dark environment.

  Conventionally, a keyboard device capable of ensuring good operability even in a dark environment has been developed. For example, there is a structure shown in FIG. Referring to FIG. 17, letters, symbols, and the like are printed on the upper surface of the key top 1, an elastic member 2 and a link mechanism 3 are provided at the lower portion of the key top 1, and a contact portion 4 is provided at the lower portion thereof. A membrane sheet 5 and a reinforcing plate 6 are disposed. An EL light emitting unit 7 is provided on the upper part of the membrane sheet 5.

  The EL light emitting unit 7 is formed on a dedicated sheet 8 by printing, and light is irradiated from the back side of the key top 1 by the EL light emitting unit 6. By irradiating light from the back side of the key top 1, characters, symbols, and the like printed on the key top 1 appear brightly illuminated. JP-A-2002-251937, for example, discloses a key switch that illuminates the key top 1 using such an EL element.

  JP 2002-251937 A

  However, the key switch structure using the above-described conventional EL element generally has a relatively short illumination lifetime of about 3000 hours, and the information processing equipment, measuring equipment, or There was a problem that it could not be used for medical devices. Furthermore, in order to illuminate, there is a problem that the product is expensive because an inverter that supplies high-frequency and high-voltage AC is essential.

  In addition, when providing an EL element on a keyboard having a link mechanism part widely adopted in notebook computers, it is difficult to provide an EL element directly below the link mechanism part provided on the back surface of the key top. It must be placed in places other than directly below. Therefore, there is a problem that it is difficult to obtain uniform and good illumination of the key top.

Accordingly, an object of the present invention is to provide a key switch structure that has a long illumination lifetime, is relatively inexpensive, and can obtain a uniform and good illumination state.

  In order to solve the above-described problems, the present invention provides a key top having a light-transmitting letter portion, a contact portion, a light-transmitting membrane sheet, and a lower portion of the membrane sheet. And a plate member having a light transmission part and a light source disposed under the plate member, and emitting the light source to emit the light source part through the plate member and the membrane sheet. It is characterized by illuminating. A light emitting diode is used as the light source.

According to the present invention, the membrane sheet is formed to be light transmissive, and the plate member disposed below the membrane sheet is formed to be light transmissive, and the light source is disposed substantially directly below the key top. Therefore, a uniform and favorable illumination state can be obtained. Further, by using a light emitting diode as a light source, an inexpensive device having a long illumination lifetime can be obtained.
The present invention thus configured can increase the operational efficiency of the remote window terminal by enabling the processing of other customers to be executed while internal processing such as examination is being performed.

FIG. 3 is an exploded perspective view illustrating a key switch structure according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a key switch structure according to the first embodiment. It is explanatory drawing which shows the positional relationship of a blank character part and LED. It is sectional drawing which shows a switch closed state. It is explanatory drawing which shows the illumination state in Example 1. FIG. It is a disassembled perspective view which shows the key switch structure of Example 2. FIG. It is explanatory drawing which shows the positional relationship of a keytop and LED. It is explanatory drawing which shows the illumination state in Example 2. FIG. It is a disassembled perspective view which shows the key switch structure of Example 3. FIG. It is explanatory drawing which shows the illumination state in Example 3. FIG. It is a disassembled perspective view which shows the key switch structure of Example 4. FIG. It is explanatory drawing which shows the positional relationship of a keytop and a reflection part. It is explanatory drawing which shows the illumination state in Example 4. FIG. FIG. 10 is an exploded perspective view illustrating a key switch structure according to a fifth embodiment. It is explanatory drawing which shows the positional relationship of a keytop and a reflection part. It is explanatory drawing which shows the illumination state in Example 5. FIG. It is sectional drawing which shows the conventional key switch structure.

  Embodiments of a key switch structure according to the present invention will be described below with reference to the drawings.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals. FIG. 1 is an exploded perspective view showing the key switch structure of the first embodiment, and FIG. 2 is a cross-sectional view showing the key switch structure of the first embodiment.

  1 and 2, the key switch 10 of the first embodiment is provided with a key top 11, a first link member 12 that is slidable with respect to the key top 11, and a rotation with respect to the key top 11. When the second link member 13 and the key top 11 are pressed, they are bent, and when the pressing force is removed, the rubber dome (elastic member) 14 that returns the key top 11 to the original position is returned. The holder 15 that holds the link members 12 and 13, the membrane sheet 16 that has a contact portion immediately below the rubber dome 14, and the holes 17 a that fix the welding pins 15 a of the holder 15, are formed of a permeable material. A back plate (plate member) 17 and a printed wiring board 19 disposed on the back side of the back plate 17 via a spacer 18 (shown in FIG. 2). It has been.

  As shown in FIG. 2, the key top 11 is formed on a main body part 11a formed of a transparent or translucent resin whose light transmission degree is arbitrarily adjusted, and on the upper part of the main body part 11a, and suppresses light transmission. For this purpose, it has a coating portion 11b with a single color or multicolor coating adjusted for the purpose, and a cutout character portion 11c in which a cutout character or a cutout symbol is formed by removing the paint in the form of a character or symbol by laser marking or the like. . The blank character portion 11c includes all characters, symbols, numbers, and the like that are normally printed on the top surface of the key top 11.

  On the back surface of the key top 11, a rotation support portion 11d that supports one end of the first link member 12 rotatably, and a slide support portion that supports one end of the second link member 13 rotatably and movable in the horizontal direction. 11e is provided. The first link member 12 has a pair of leg portions 12a and 12b, and a first connecting rod 12c inserted and supported by the rotation support portion 11d of the key top 11 is provided at one end of the leg portions 12a and 12b. 12b, similarly, a second connecting rod 12d is provided at the other end of the leg portions 12a, 12b so as to connect the leg portions 12a, 12b. On the outer surface of each of 12b, shafts 12e and 12f are provided at positions that are on a line connecting the first connecting rod 12c and the second connecting rod 12d and are equidistant from each connecting rod 12c and 12d. It has been.

  The second link member 13 has a pair of leg portions 13a and 13b, and is supported at one end of the leg portions 13a and 13b by the slide support portion 11e of the key top 11 so as to be rotatable and parallelly movable in the horizontal direction. The first support protrusions 13c and 13d are provided outward and the other end is provided with the second support protrusions 13e and 13f outward at the same distance as between the connecting rods 12c and 12d of the first link member 12. ing. Further, shaft holes 13g and 13h are located on the line connecting the first support protrusions 13c and 13d and the second support protrusions 13e and 13f and at equal distances to the support protrusions 13c and 13d; 13e and 13f. Is provided. Further, the leg portions 13a and 13b are connected by a connecting portion 13i on the tip side of the first support protrusions 13c and 13d.

  The rubber dome 14 is formed in a substantially cup shape using rubber or the like as a raw material, and a contact pressing portion 14a is formed to protrude downward at the center of the inner surface. The holder 15 is divided into one key unit and is formed in a frame shape. A slide guide 15b for supporting the second connecting rod 12d of the first link member 12 so as to be rotatable and horizontally movable in the vicinity of one end thereof. In the vicinity of the other end, rotation guides 15c and 15d for rotatably supporting the second support protrusions 13e and 13f of the second link member 13 are provided.

  Further, an arcuate guide wall 15e for fixing the outer periphery of the rubber dome 14 is provided at the center of both ends of the holder 15 so as to face each other, and the lower surface of the holder 15 surrounds the through hole 16f of the membrane sheet 16. The welding pins 15a having a predetermined length are formed at a plurality of locations.

  As shown in FIG. 2, the membrane sheet 16 includes two flexible sheets 16a and 16b and a spacer sheet 16c sandwiched between the two flexible sheets 16a and 16b. Are provided with a plurality of through holes 16f corresponding to a plurality of keys. The through-hole 16f forms a space between the two flexible sheets 16a and 16b, and the fixed contact 16d is provided on the flexible sheet 16b on the back plate 17 side so as to be positioned to face each other in this space. The movable contact 16e is provided on the flexible sheet 16a on the rubber dome 14 side.

  The fixed contact 16d and the movable contact 16e constitute a contact portion. The membrane sheet 16 is provided with a plurality of through holes 16g so as to be located around the through hole 16f. The membrane sheet 16 has an uneven surface and is entirely formed of a light transmissive member.

  The back plate 17 is disposed at the lower part so as to mount the above-described components, and is formed of a permeable member. The back plate 17 is formed with spacer projections 17b having a thickness equivalent to that of the membrane sheet 16 corresponding to the through holes 16g of the membrane sheet 16, and a welding pin 15a of the holder 15 is provided at the center of each spacer projection 17b. A through hole 17a is provided so as to pass therethrough, and a recess (a counterbore) is formed around each hole 17a on the lower surface side of the back plate 17. The upper surface of the back plate 17 is formed in a concavo-convex shape, and diffuses light transmitted from the lower part upward.

  A printed wiring board 19 is disposed below the back plate 17. The printed wiring board 19 is provided with an LED (light emitting diode) 20. As shown in FIG. 3, the LED 20 is disposed immediately below the cutout character portion 11 c of the key top 11 in a state where the key switch 10 is assembled. FIG. 3 is an explanatory diagram showing the positional relationship between the extracted character portion 11 c of the key top 11 and the LED 20. FIG. 3A shows an example in which the LEDs 20 are arranged horizontally, and FIG. 3B shows an example in which the LEDs 20 are arranged vertically.

  Next, the operation will be described. In FIG. 2, when the key top 11 is pressed from above with an arbitrary load, the key top 11 moves downward, whereby the rubber dome 14 is bent, and the contact pressing portion 14a of the rubber dome 14 is as shown in FIG. Then, the contact portions 16d and 16e of the membrane sheet 16 are pressed. As a result, the switch is closed. Further, regardless of which portion of the top of the key top 11 is pressed by the first link member 12 and the second link member 13, the key top 11 moves downward while maintaining the horizontal state, and the switch closed state is obtained. . FIG. 4 is a sectional view showing the switch closed state.

  FIG. 5 is an explanatory diagram illustrating an illumination state in the first embodiment. In FIG. 5, the LED 20 disposed on the printed wiring board 19 is turned on when a power supply (not shown) is turned on. The light emitted from the LED 20 first passes through the back plate 17 formed of a transparent resin. Since the surface of the back plate 17 has a concavo-convex shape 17 c, the light that has passed through the back plate 17 diffuses as indicated by the arrows when exiting from the back plate 17.

  The light diffused and passed through the back plate 17 passes through the membrane sheet 16 because the membrane sheet 16 is light transmissive. The light passing at this time is diffused again by the irregularities 16 h on the surface of the membrane sheet 16 when it exits the membrane sheet 16. A part of the diffused light passes through the first link member 12 and the second link member 13 from the outside of the rubber dome 14 and reaches the back surface of the key top 11.

  The key top 11 is formed with a cut-out character portion 11c. When light is irradiated on the cut-out character portion 11c from the back surface, it looks like a letter or symbol formed on the top surface of the key top 11.

  The light emitted from the LED 20 is extremely directional. However, according to the first embodiment, the light emitted from the LED 20 disposed on the printed wiring board 19 is a back plate formed of a transparent resin. The first and second link members provided on the top of the membrane sheet 16 are diffused by the surface irregularities 17c when passing through the membrane 17, and further diffused by the surface irregularities 16h when passing through the membrane sheet 16. 12 and 13 can be passed through to reach the bottom surface of the key top 11. As a result, it is possible to illuminate the extracted character portion 11 c formed on the key top 11. By finely diffusing the light, the light illuminating the extracted character portion 11c becomes uniform, and when viewed from the top of the key top 11, it becomes easy to see characters, symbols, and the like.

  Next, Example 2 will be described. FIG. 6 is an exploded perspective view showing the key switch structure of the second embodiment. In FIG. 6, a key top 11 is formed on a main body part 11a formed of a transparent or translucent resin whose light transmission degree is arbitrarily adjusted and an upper part of the main body part 11a, as in the first embodiment. The painted portion 11b with a single color or multi-color coating adjusted to suppress the transmission of light, and the blank character portion formed with the blank character or the blank symbol by removing the paint into the shape of the character or symbol by laser marking or the like 11c.

  The rubber dome 24 is formed in a substantially cup shape from a transparent material, and a contact pressing portion 24a is formed to protrude downward at the center of the inner surface. Fine irregularities are formed on the surface of the rubber dome 24. The lowermost printed wiring board 19 is provided with LEDs 20. As shown in FIG. 7, the LED 20 is disposed immediately below the center of the key top 11 in a state where the key switch is assembled. By disposing the LED 20 directly below the center of the key top 11, the LED 20 is positioned directly below the contact portion between the rubber dome 24 and the membrane sheet 16. FIG. 7 is an explanatory diagram showing the positional relationship between the key top 11 and the LED 20. Fig.7 (a) shows the example which has arrange | positioned LED20 horizontally long, FIG.7 (b) shows the example which has arrange | positioned LED20 vertically long. Other configurations are the same as those of the first embodiment.

  Next, the operation will be described. Here, illumination by the LED 20 will be described. FIG. 8 is an explanatory diagram illustrating an illumination state according to the second embodiment. In FIG. 8, the LED 20 disposed on the printed wiring board 19 is turned on when a power supply (not shown) is turned on. The light emitted from the LED 20 first passes through the back plate 17 formed of a transparent resin. Since the surface of the back plate 17 has a concavo-convex shape 17 c, the light that has passed through the back plate 17 diffuses as indicated by the arrows when exiting from the back plate 17.

  The light diffused and passed through the back plate 17 passes through the membrane sheet 16 because the membrane sheet 16 is light transmissive. The light passing at this time is diffused again by the irregularities 16 h on the surface of the membrane sheet 16 when it exits the membrane sheet 16. The diffused light enters the inside of the rubber dome 24 and further passes through the rubber dome 24. The light passing at this time is further diffused by the unevenness 24 b on the surface of the rubber dome 24 when it exits the rubber dome 24. The diffused light passes through the first link member 12 and the second link member 13 and reaches the back surface of the key top 11.

  The key top 11 is formed with a cutout character portion 11c. When light is irradiated on the cutout character portion 11c, it looks like a letter or symbol formed on the top surface of the keytop 11.

  As described above, according to the second embodiment, the light emitted from the LED 20 disposed on the printed wiring board 19 is diffused by the unevenness 17c on the surface when passing through the back plate 17 formed of the transparent resin. Also, when passing through the membrane sheet 16, it is diffused by the surface irregularities 16h, and when passing through the rubber dome 24, it is also diffused by the surface irregularities 24b. The second link members 12 and 13 can be passed through to reach the lower surface of the key top 11. As a result, it is possible to illuminate the extracted character portion 11 c formed on the key top 11 more uniformly than in the first embodiment.

  In the second embodiment, an example in which the LED 20 is provided immediately below the center of the key top 11 is shown. However, in the case of a large key, the position where characters or symbols are formed on the key top 11 and the center position of the key top In this case, the LED 20 is arranged almost immediately below the formation position of characters, symbols, and the like.

  Next, Example 3 will be described. FIG. 9 is an exploded perspective view showing the key switch structure of the third embodiment. In FIG. 9, a key top 11 is formed on a main body part 11a formed of a transparent or translucent resin whose light transmission degree is arbitrarily adjusted and an upper part of the main body part 11a, as in the first embodiment. The painted portion 11b with a single color or multi-color coating adjusted to suppress the transmission of light, and the blank character portion formed with the blank character or the blank symbol by removing the paint into the shape of the character or symbol by laser marking or the like 11c.

  A backlight unit 21 is provided below the back plate 17. The backlight unit 21 uniformly irradiates light to the entire lower portion of the back plate 17, and includes a fluorescent tube 21a and a reflecting plate 21b, which are light emission sources. Other configurations are the same as those of the first embodiment.

  FIG. 10 is an explanatory diagram illustrating an illumination state in the third embodiment. In FIG. 10, the fluorescent tube 21a of the backlight unit 21 is turned on when a power supply (not shown) is turned on. The light emitted from the fluorescent tube 21a is reflected by the reflecting plate 21b and first passes uniformly through the back plate 17 formed of a transparent resin. Since the surface of the back plate 17 has a concavo-convex shape 17 c, the light that has passed through the back plate 17 diffuses as indicated by the arrows when exiting from the back plate 17.

  The light diffused and passed through the back plate 17 passes through the membrane sheet 16 because the membrane sheet 16 is light transmissive. The light passing at this time is diffused again by the irregularities 16 h on the surface of the membrane sheet 16 when it exits the membrane sheet 16. A part of the diffused light passes through the first link member 12 and the second link member 13 from the outside of the rubber dome 14 and reaches the back surface of the key top 11.

  The key top 11 is formed with a cutout character portion 11c. When light is irradiated on the cutout character portion 11c, it looks like a letter or symbol formed on the top surface of the keytop 11.

  In the third embodiment, the light emitted from the backlight unit 21 uniformly passes through the back plate 17 and is then diffused in the same manner as in the first embodiment and reaches the back surface of the key top 11. Thus, it is possible to illuminate the character portion 11c even more uniformly. In the third embodiment, the rubber dome 14 may be formed of a transparent material as in the second embodiment. Further, as a configuration of the backlight unit 21, instead of providing the fluorescent tube 21a as a light source at the end of the reflection plate 21b, a plurality of fluorescent tubes may be equally arranged at a plurality of locations inside the reflection plate.

  Next, Example 4 will be described. FIG. 11 is an exploded perspective view showing the key switch structure of the fourth embodiment. In FIG. 11, a key top 11 is formed on a main body part 11a formed of a transparent or translucent resin whose light transmission degree is arbitrarily adjusted and an upper part of the main body part 11a, as in the first embodiment. The painted portion 11b with a single color or multi-color coating adjusted to suppress the transmission of light, and the blank character portion formed with the blank character or the blank symbol by removing the paint into the shape of the character or symbol by laser marking or the like 11c.

  The rubber dome 24 is formed in a substantially cup shape from a transparent material, and a contact pressing portion 24a is formed to protrude downward at the center of the inner surface. Fine irregularities are formed on the surface of the rubber dome 24.

  A light guide plate 22 is disposed below the back plate 17. The light guide plate 22 is made of a highly permeable resin, and light passes through the inside while bending. A plurality of reflection portions 23 are formed on the light guide plate 22. As shown in FIG. 12, the reflection portion 23 is provided immediately below the center portion of the key top 11. Further, as shown in FIG. 13, the reflecting portion 23 is formed in a conical shape, and its upper surface 23a and side surface 23b are light reflecting surfaces. FIG. 12 is an explanatory view showing the positional relationship between the key top and the reflecting portion, and FIG. 13 is an explanatory view showing an illumination state in the fourth embodiment.

  In FIG. 11, an LED array 24 is provided at one end of the light guide plate 22. The LED array 24 has a plurality of LED light sources 25 arranged in a line along the surface of the light guide plate 22, and the LED array 24 irradiates one side 22 a of the light guide plate 22 with light. A reflective member 26 is provided on the other side surfaces 22 b, 22 c, and 22 d of the light guide plate 22. Other configurations are the same as those of the first embodiment.

  In FIG. 13, the LED array 24 arranged to face the one side surface 22a of the light guide plate 22 is turned on when a power supply (not shown) is turned on. Light emitted from the LED array 24 passes through the light guide plate 22 while being bent. Light is reflected on the upper surface 23 a and the side surface 23 b of the reflecting portion 23 formed immediately below the center of the key top 11, and part of the reflected light enters the back plate 17. Since the side surface 23b is formed obliquely, the light that has passed through the light guide plate 22 is reflected toward the back plate 17.

  The light that does not strike the reflecting portion 23 is reflected by the reflecting member 26 provided on the side surfaces 22b, 22c, and 22d. The light reflected by the reflecting member 26 passes through the light guide plate 22 again, and a part of the light is reflected by the reflecting portion 23. By repeating this, a relatively large amount of light enters the back plate 17.

  The light that has entered the back plate 17 passes upward through the back plate 17 formed of a transparent resin, and diffuses by the uneven shape 17 c when exiting from the back plate 17. The light that has passed through the back plate 17 passes through the membrane sheet 16 because the membrane sheet 16 is light transmissive. The light passing at this time is diffused again by the irregularities 16 h on the surface of the membrane sheet 16 when it exits the membrane sheet 16. A part of the diffused light enters the inside of the rubber dome 24 and further passes through the rubber dome 24. The light passing at this time is further diffused by the unevenness 24 b on the surface of the rubber dome 24 when it exits the rubber dome 24. The diffused light passes through the first link member 12 and the second link member 13 and reaches the back surface of the key top 11.

  The key top 11 is formed with a cutout character portion 11c. When light is irradiated on the cutout character portion 11c, it looks like a letter or symbol formed on the top surface of the keytop 11.

  As described above, the fourth embodiment can achieve the same effects as the second embodiment. Further, in the fourth embodiment, the number of LEDs can be reduced as compared with the second embodiment in which LEDs are provided by the number of keys. Therefore, it is possible to reduce the cost of the LED and the cost for mounting the LED, and realize an inexpensive illuminated keyboard. can do.

  Next, Example 5 will be described. FIG. 14 is an exploded perspective view showing the key switch structure of the fifth embodiment. In FIG. 14, a key top 11 is formed on a main body part 11a formed of a transparent or translucent resin whose light transmission degree is arbitrarily adjusted and an upper part of the main body part 11a, as in the first embodiment. The painted portion 11b with a single color or multi-color coating adjusted to suppress the transmission of light, and the blank character portion formed with the blank character or the blank symbol by removing the paint into the shape of the character or symbol by laser marking or the like 11c.

  A light guide plate 22 is disposed below the back plate 17 as in the fourth embodiment. The light guide plate 22 is made of a highly permeable resin, and light passes through the inside while bending. A plurality of reflecting portions 27 are formed on the light guide plate 22. As shown in FIG. 15, the reflection portion 27 is provided immediately below the blank character portion 11 c of the key top 11. As shown in FIG. 16, the reflecting portion 27 is formed in a conical shape, and its upper surface 27a and side surface 27b are light reflecting surfaces. FIG. 15 is an explanatory view showing the positional relationship between the key top and the reflecting portion, and FIG. 16 is an explanatory view showing an illumination state in the fifth embodiment.

  In FIG. 14, the LED array 24 is provided at one end of the light guide plate 22 as in the fourth embodiment. The LED array 24 has a plurality of LED light sources 25 arranged in a line along the surface of the light guide plate 22, and the LED array 24 irradiates one side 22 a of the light guide plate 22 with light. A reflective member 26 is provided on the other side surfaces 22 b, 22 c, and 22 d of the light guide plate 22.

  In FIG. 16, the LED array 24 arranged to face the one side surface 22a of the light guide plate 22 is turned on when a power supply (not shown) is turned on. Light emitted from the LED array 24 passes through the light guide plate 22 while being bent. Light is reflected on the upper surface 27 a and the side surface 27 b of the reflecting portion 27 formed immediately below the extracted character portion 11 c of the key top 11, and a part of the reflected light enters the back plate 17. Since the side surface 27b is formed obliquely, the light passing through the light guide plate 22 is reflected toward the back plate 17.

  The light that does not strike the reflecting portion 27 is reflected by the reflecting member 26 provided on the side surfaces 22b, 22c, and 22d. The light reflected by the reflecting member 26 passes through the light guide plate 22 again, and a part of the light is reflected by the reflecting portion 27. By repeating this, a relatively large amount of light enters the back plate 17.

  The light that has entered the back plate 17 passes upward through the back plate 17 formed of a transparent resin, and diffuses by the uneven shape 17 c when exiting from the back plate 17. The light that has passed through the back plate 17 passes through the membrane sheet 16 because the membrane sheet 16 is light transmissive. The light passing at this time is diffused again by the irregularities 16 h on the surface of the membrane sheet 16 when it exits the membrane sheet 16. A part of the diffused light passes through the first link member 12 and the second link member 13 from the outside of the rubber dome 14 and reaches the back surface of the key top 11.

  The key top 11 is formed with a cutout character portion 11c. When light is irradiated on the cutout character portion 11c, it looks like a letter or symbol formed on the top surface of the keytop 11.

  According to the fifth embodiment, the same effect as the first embodiment can be obtained. Further, in the fifth embodiment, the number of LEDs can be reduced as compared with the first embodiment in which LEDs are provided by the number of keys, so that the cost of the LEDs and the cost for mounting the LEDs can be reduced, and an inexpensive illuminated keyboard is realized. can do.

11 Key top 11c Uncut character parts 14, 24 Rubber dome 16 Membrane sheet 17 Back plate 19 Printed wiring board 20 LED
21 Backlight unit 24 LED array 23, 27 Reflector

Claims (6)

A key top on which a light-transmitting blank portion is formed; and
A membrane sheet comprising a contact part and a through-hole part and having light permeability ;
A plate member having a protrusion and having light transparency;
A light source disposed at a lower portion of the plate member,
By positioning the protrusion corresponding to the through hole, the plate member is disposed at the lower part of the membrane sheet ,
A key switch structure characterized by illuminating the extracted character portion of the key top through the plate member and the membrane sheet by causing the light source to emit light. A holder for holding a link member slidably provided with respect to the key top;
2. The key switch structure according to claim 1, wherein the holder is provided with a pin portion, and the holder is fixed to the plate member when the pin portion passes through the protrusion. A light guide plate is provided below the plate member,
3. The key switch structure according to claim 1, wherein the light source includes a light emitting element portion that is arranged at one end portion of the light guide plate and emits light in a surface direction of the light guide plate . The key switch structure according to claim 3, wherein the light guide plate is provided with a reflection portion that reflects light emitted from the light emitting element portion in a direction of the extracted character portion of the key top. It is arranged between the key top and the membrane sheet, is composed of a light transmissive member, has an elastic member that returns to the position based on the pressed key top, and the light guide plate from the light emitting element portion The key switch structure according to claim 3, further comprising a reflecting portion that reflects emitted light toward the elastic member.   6. The key switch structure according to claim 4, wherein the reflection portion is formed in a conical shape.

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