Switch knob lighting structure

Abstract

To illuminate a predetermined portion of a switch knob with more uniform brightness.SOLUTION: A structure 10 for illuminating a switch knob 1 comprises: a tact switch; a switch knob 1 arranged on a surface part separated from a substrate on which the tact switch is arranged so as to correspond to the tact switch; a light source 6 that illuminates a predetermined portion of the switch knob on the surface part; and a push boss 3 that propagates to the tact switch a depression reaction from the switch knob 1. The push boss 3 has: a pressure reception surface part 3a that receives a pressing force of the switch knob 1; and a wall part 3b provided at a different position from the pressure reception surface part 3a.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an illumination structure for a switch knob. [Background technology]

[0002] Patent Document 1 describes an illumination structure for a switch knob that illuminates a predetermined portion of the switch knob by pressing down the switch knob. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-105783 Summary of the Invention [Problem to be solved by the invention]

[0004] The lighting structure of the switch knob described in Patent Document 1 is not necessarily satisfactory in terms of appearance because the light emitted from the light source causes unevenness in the specific area to be illuminated. Therefore, it may not be easy to illuminate the specific area uniformly, and there is room for improvement.

[0005] The present invention has been made in view of the above, and provides an illumination structure for a switch knob that can emit light uniformly without unevenness in a predetermined portion of the switch knob. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the illumination structure for a switch knob according to the present invention comprises a tact switch that converts a user's pressing reaction into an electrical signal, a switch knob that is arranged on a surface portion spaced from a substrate on which the tact switch is arranged and corresponds to the tact switch, a light source that is arranged on the substrate and illuminates a predetermined portion of the switch knob on the surface portion, and a push boss that is arranged between the tact switch and the switch knob and transmits the user's pressing reaction from the switch knob to the tact switch, wherein the push boss has a pressure-receiving surface portion that receives the pressing force of the switch knob, and a wall portion that is provided at a position different from the pressure-receiving surface portion, and an arm portion extending from the pressure-receiving surface portion has an orthogonal arm portion that extends perpendicular to a virtual straight line connecting a part of the predetermined portion of the switch knob that is illuminated by light reflected by the wall portion and the light source, between a part of the predetermined portion of the switch knob that is illuminated by light reflected by the wall portion and the wall portion. Effect of the Invention

[0007] According to the present invention, it is possible to achieve the effect of uniformly emitting light without unevenness in a predetermined portion of the switch knob. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a front view showing a part of an electronic device including an illumination structure for a switch knob according to a first embodiment. [Diagram 2] FIG. 2 is a vertical cross-sectional view showing the illumination structure of the switch knob according to the first embodiment, taken along the line AA in FIG. [Diagram 3] FIG. 3 is a rear perspective view showing the illumination structure of the switch knob according to the first embodiment as viewed from the rear side. [Figure 4] FIG. 4 is an explanatory diagram showing an optical path of reflected light in the illumination structure of the switch knob according to the first embodiment. [Diagram 5] FIG. 5 is an explanatory diagram showing an illumination state in the illumination structure for the switch knob according to the first embodiment in comparison with a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the switch knob illumination structure according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiment. [First embodiment] <Configuration of Electronic Device 100> Fig. 1 is a front view showing a part of an electronic device 100 including an illumination structure 10 for a switch knob 1 according to a first embodiment. For convenience of explanation, the up, down, left, right, front, and rear directions are defined as the directions of the arrows shown in Fig. 1. These up, down, left, right, front, and rear directions do not limit the directions of the illumination structure 10 in the usage posture, etc. In addition, the other drawings follow the directions in Fig. 1.

[0010] The switch knob 1 is a seesaw switch provided on an operation panel 101 of an electronic device 100. The electronic device 100 is, for example, a car navigation device. Fig. 1 shows a part of the electronic device 100. As shown in Fig. 1, the switch knob 1 is disposed in a light-transmitting portion 102 provided on the operation panel 101, and is a member having an outer shape of a six-point star when viewed from the front. <Configuration of the lighting structure 10 of the switch knob 1> 2 is a vertical cross-sectional view showing an illumination structure 10 for a switch knob 1 according to the first embodiment, taken along the line AA in FIG. 1. As shown in FIG. 2, the switch knob 1 is disposed on a front surface 101a of an operation panel 101 spaced apart from a substrate 11. The switch knob 1 moves in a seesaw manner in response to a user's pressing reaction. The switch knob 1 switches the tactile switch 2 between on and off in response to the user's pressing reaction. A protrusion (not shown) may be formed on the switch knob 1, and the user may be able to tactilely guide the position to be pressed with the finger of the user to operate the switch knob 1 by the feel of the protrusion.

[0011] The tactile switch 2 converts the user's reaction of pressing the switch knob 1 into an electrical signal. The tactile switch 2 is disposed on a substrate 11. A push boss 3 is interposed between the tactile switch 2 and the switch knob 1.

[0012] An illumination section 4, formed here by a light-transmitting section 102, is formed on the outer periphery of the switch knob 1 formed on the surface section 101a of the operation panel 101, between the outer periphery of the switch knob 1 and the surface section 101a of the operation panel 101 spaced apart from the outer periphery of the switch knob 1. The illumination section 4 is an area formed by a gap around the outer periphery of the switch knob 1 formed on the surface of the operation panel 101. The illumination section 4 is formed by a gap, thereby ensuring the operability of the switch knob 1. That is, by forming the illumination section 4 as a gap, light leaks from the light-transmitting section 102 at night, making it easy to see where the switch knob 1 is mounted. As shown in FIG. 1, in this example, the illumination section 4 is formed in the outline shape of a six-star mark, "star." Note that the illumination section 4 may be formed not as a gap, but as a light-transmitting member covered with a transparent member or the like.

[0013] A push boss 3 is disposed between the tactile switch 2 and the switch knob 1. The push boss 3 transmits the user's push reaction from the switch knob 1 to the tactile switch 2. The push boss 3 is provided upright at a position corresponding to a protrusion on the inner surface of the switch knob 1. An elastic member (not shown) is interposed between the switch knob 1 and the push boss 3. The elastic member biases the switch knob 1 forward. The push boss 3 receives the pushing force of the switch knob via the elastic member.

[0014] When an external force is applied by the user's finger or the like to the switch knob 1 inside the light-transmitting portion 102, the top, bottom, left, right, and other ends can be pushed backward against the biasing force of the elastic member. When the finger pressing the switch knob 1 is released, the switch knob 1 returns to its normal position due to the elastic repulsive force of the elastic member.

[0015] The substrate 11 is disposed parallel to and spaced apart from the switch knob 1. A light source 6 is disposed on the substrate 11 for illuminating a predetermined portion of the switch knob 1 on the surface portion 101a of the operation panel 101. The light source 6 is mounted on the substrate 11 in correspondence with the illumination unit 4 so as to emit light to the illumination unit 4. The light source 6 is, for example, an LED chip, and emits light in an on state and goes out in an off state in response to a switching operation of the tact switch 2 or in conjunction with a headlight switch of the vehicle.

[0016] A push portion 2a that is pressed to activate the switch is provided on the front side of the tact switch 2. When the switch knob 1 is in the normal position, the push portion 2a is separated forward from the tip of the push boss 3, and is pressed by the tip of the push boss 3 when a predetermined portion of the switch knob 1 is pressed rearward. This causes the tact switch 2 to operate in accordance with the push boss 3. <Structure of Push Boss 3> Fig. 3 is a rear perspective view showing the illumination structure 10 of the switch knob 1 according to the first embodiment as seen from the rear side. Fig. 4 is an explanatory diagram showing an optical path of reflected light Rl in the illumination structure 10 of the switch knob 1 according to the first embodiment. In the following description, for ease of understanding, it is assumed that the light source 6 outputs light from a light-emitting portion Lp serving as a point light source.

[0017] As shown in Fig. 3, the push boss 3 has a pressure-receiving surface portion 3a and a wall portion 3b in cross section. The push boss 3 may have, for example, a substantially U-shaped cross section as a whole. The push boss 3 is preferably a light-transmitting member that transmits light. Depending on the shape of the illumination unit 4, the push boss 3 may be a non-light-transmitting member that does not transmit light.

[0018] The pressing force of the switch knob 1 is transmitted to the pressing boss 3, and then to the tactile switch 2 via the pressure receiving surface portion 3a.

[0019] The wall portion 3b is provided at a position different from the pressure-receiving surface portion 3a. That is, the wall portion 3b is formed by an arm portion 3c extending from the pressure-receiving surface portion 3a on the back side of the operation panel 101 at the pressure-receiving surface portion 3a. The wall portion 3b is in contact with the back side of the operation panel 101 together with the pressure-receiving surface portion 3a. The wall portion 3b is formed by an arm portion 3c extending from the pressure-receiving surface portion 3a in a direction other than the front and rear. A pair of arms 3c are provided. The wall portion 3b is integrally molded with the push boss 3. 4, the pair of arms 3c are formed to extend downward from the pressure-receiving surface 3a to both the left and right sides in line symmetry with respect to a vertical imaginary straight line B connecting a part P of a predetermined portion of the switch knob 1 and the light source 6. The pair of arms 3c may be formed to extend downward from both the left and right sides of the pressure-receiving surface 3a in line symmetry in an arc shape.

[0020] The orthogonal arms 3c1 are the portions of the pair of arms 3c that extend from the pressure-receiving surface 3a to both the left and right sides in line symmetry with respect to a virtual line in the up-down direction. As shown in Fig. 4, the orthogonal arms 3c1 extend between a part P of a predetermined portion of the switch knob 1 that is illuminated by reflected light by the reflecting surface 3d of the wall 3b and the reflecting surface 3d of the wall 3b, perpendicular to a virtual straight line B that connects the part P of the predetermined portion of the switch knob 1 that is illuminated by reflected light Rl by the reflecting surface 3d of the wall 3b and the light source 6. The orthogonal arms 3c1 are disposed at a position that does not obstruct the optical path of the reflected light Rl.

[0021] As shown in Fig. 3, each wall 3b of the pair of arms 3c extends downward from the tip of the arm 3c. As shown in Fig. 4, the wall 3b has a reflection surface 3d parallel to a virtual straight line B in the vertical direction connecting the light source 6 and a part P of a predetermined part of the switch knob 1 illuminated by the reflected light Rl by the wall 3b.

[0022] As shown in Figure 4, the reflective surface 3d on the surface of the wall portion 3b illuminates the specified portion P of the switch knob 1 with reflected light Rl from both sides in a line-symmetric manner with respect to an imaginary straight line B that connects the specified portion P of the switch knob 1 illuminated by the reflective surface 3d of the wall portion 3b with the light source 6. That is, the reflective surface 3d of the wall portion 3b reflects the light emitted from the light source 6 and reaching the reflective surface 3d of the wall portion 3b, and illuminates a part P of a predetermined portion of the switch knob 1 with the reflected light Rl.

[0023] The wall 3b is a transparent member. The push boss 3 is also made of a transparent member including the pressure receiving surface 3a and the pair of arms 3c in addition to the wall 3b. The wall 3b is made of a transparent plastic material such as polycarbonate or acrylic. The wall 3b may be made of a mirror-polished metal material, an aluminum-deposited material, or a material coated with high-brightness paint. The wall 3b reflects light that reaches the reflective surface 3d of the wall 3b. However, the present invention is not limited to this, and the wall 3b may reflect light that reaches the inside of the wall 3b or the outer surface after passing through the inside of the wall 3b. In other words, the wall 3b may reflect light that reaches other than the reflective surface 3d of the wall 3b.

[0024] The entire portion of the wall portion 3b including the reflective surface 3d has a shape in which the angle of incidence of light emitted from the light source 6 exceeds the critical angle for reflecting light. As a result, when the reflective surface 3d of the wall portion 3b is made of a transparent material, it can reflect the light emitted from the light source 6 as reflected light Rl toward a part P of a predetermined portion of the switch knob 1.

[0025] Here, the reason why the uneven light occurs in the past is that the light from the light source 6 is reflected by the thick wall portion 3a2 shown in FIG. 3 without being transmitted, and the light is difficult to reach the part P of the predetermined part of the switch knob 1. As a result, the part P of the predetermined part of the switch knob 1 becomes dark, and uneven light occurs compared to the surroundings of the part P of the predetermined part. The reason why the light does not transmit through the thick wall portion 3a2 is that the angle of the light from the light source 6 incident on the thick wall portion 3a2 exceeds about 40 degrees, although the angle varies depending on the material, and the light is totally reflected without being transmitted. Therefore, the light of the part P of the predetermined part of the switch knob 1 is weak due to the light reflection of the thick wall portion 3a2. To improve this, the light is reflected on the reflecting surface 3d of the wall portion 3b to collect the light on the part P of the predetermined part of the switch knob 1 to compensate for the light of the part P of the predetermined part of the switch knob 1. As a result, the brightness of the part P of the predetermined part of the switch knob 1 becomes the same as that of its surroundings, and the appearance is improved by uniformly emitting light.

[0026] Here, as shown in FIG. 2 and FIG. 3, the reflecting surface 3d, which reflects the light emitted from the light source 6 on the wall portion 3b and reaches the wall portion 3b to illuminate the part P of the predetermined part of the switch knob 1 with the reflected light Rl, has an area that makes the amount of light of the part P of the predetermined part of the switch knob 1 illuminated by the reflected light Rl by the reflecting surface 3d of the wall portion 3b equal to the amount of light of other parts of the switch knob 1 other than the part P of the predetermined part that is directly illuminated by the light emitted from the light source 6. This makes the brightness of the illumination unit 4 almost equal. The area of ​​the reflecting surface 3d may be appropriately set by correlating the height dimension of the reflecting surface 3d of the wall portion 3b with the length dimension of the reflecting surface 3d of the wall portion 3b. In addition, when light is reflected by a part other than the reflecting surface 3d of the wall portion 3b, the area of ​​the reflecting area of ​​the wall portion 3b may be appropriately set by correlating the height dimension of the reflecting area of ​​the wall portion 3b with the length dimension of the reflecting area of ​​the wall portion 3b. <Lighting operation of the lighting structure 10 of the switch knob 1> 2, light emitted from the light-emitting unit Lp toward the lighting unit 4 in front reaches the lighting unit 4 in the operation panel 101 directly as direct light Sl, passes through the operation panel 101, and is emitted to the front side of the operation panel 101. As a result, the lighting unit 4, which is the outline of the switch knob 1, is illuminated and visually recognized by the user.

[0027] 4 from the light-emitting unit Lp, part of the light is specularly reflected as reflected light Rl by the reflective surface 3d of the wall portion 3b of the push boss 3, reaches the illumination unit 4, passes through the operation panel 101, and is emitted to the front side of the operation panel 101. That is, in the illumination structure 10, the illumination unit 4 is illuminated not only by direct light Sl from the light source 73, but also by reflected light Rl reflected by the reflective surface 3d of the wall portion 3b, particularly from a portion P of a predetermined portion of the switch knob 1. This allows the illumination unit 4 to be viewed from the outside with a more uniform brightness.

[0028] Although not shown, light emitted from the light-emitting unit Lp slightly diagonally upward to the left and right is also reflected multiple times by the reflecting surface 3d of the wall portion 3b as oblique light to illuminate the illumination unit 4. In this embodiment, the light amount of a part P of a predetermined portion of the switch knob 1 illuminated by the reflected light Rl by the wall portion 3b is made to match the light amount of a portion other than the part P of the predetermined portion of the switch knob 1 directly illuminated by light emitted from the light source 6. For this reason, it is preferable that the height dimension from the front end portion 3a1 of the pressure-receiving surface portion 3a of the wall portion 3b is adjusted so that the light amount of the oblique light is included in the light amount of the reflected light Rl. <Comparison of the illumination state in the illumination structure 10 of the switch knob 1 with a comparative example> Fig. 5 is an explanatory diagram showing an illumination state in the illumination structure of the switch knob according to the first embodiment in comparison with a comparative example. As shown in Fig. 5, in addition to the direct light Sl that directly enters the illumination unit 4 from the light source 6, the light emitted toward the wall 3b of the push boss 3 is guided to the illumination unit 4 as reflected light Rl reflected by the reflecting surface 3d of the wall 3b and is made to enter the illumination unit 4. This increases the ratio of the amount of light incident on the illumination unit 4 to the total amount of light emitted from the light source 6, and the illumination unit 4, which is a predetermined portion of the switch knob 1, can be illuminated with more uniform brightness.

[0029] The comparative example in FIG. 5, in which no wall is provided, is an illumination structure having the same configuration as that of the embodiment 1, except that no wall is provided. In the comparative example in FIG. 5, only direct light Sl is incident on the illumination unit 4, so that a part P of a predetermined part of the switch knob 1 is dark. In contrast, in the present embodiment in which the wall 3b is provided, direct light Sl and reflected light Rl are incident on the illumination unit 4, so that a part P of a predetermined part of the switch knob 1 is brightened by the reflected light Rl. That is, the illumination structure 10 has a high utilization efficiency of the light emitted from the light source 6 for the light used to illuminate the illumination unit 4. As a result, the illumination unit 4 is brightened uniformly throughout. Note that the total luminous flux in FIG. 5 is the ratio of the total luminous flux emitted from the light source 6. The reaching luminous flux is the ratio of the luminous flux reaching the illumination unit 4 from the light source 6. The total number is the number of luminous fluxes emitted from the light source 6. The reaching number is the number of luminous fluxes reaching the illumination unit 4 from the light source 6. <Effects> As described above, according to this embodiment, the push boss 3 can have a pressure-receiving surface portion 3a that receives the pressing force of the switch knob 1, and a wall portion 3b provided at a position different from the pressure-receiving surface portion 3a. According to this embodiment, the amount of light that reaches the part P of the predetermined portion of the switch knob 1 can be increased, and the entire illumination portion 4 of the switch knob 1 can be illuminated with a more uniform brightness.

[0030] According to this embodiment, the wall portion 3b reflects the light emitted from the light source 6 and reaching the wall portion 3b, and the reflected light Rl can illuminate the part P of the predetermined portion of the switch knob 1. With this configuration, the amount of reflected light Rl that reaches the part P of the predetermined portion of the switch knob 1 can be increased, and the entire illumination portion 4 of the switch knob 1 can be illuminated with more uniform brightness.

[0031] According to this embodiment, the wall portion 3b can be formed as an arm portion 3c extending from the pressure-receiving surface portion 3a. With this configuration, the wall portion 3b can be reinforced by the arm portion 3c extending from the pressure-receiving surface portion 3a.

[0032] According to this embodiment, the wall portion 3b can have a reflection surface 3d that is parallel to an imaginary line connecting the light source 6 and a part P of the predetermined portion of the switch knob 1 that is illuminated by the reflected light Rl by the wall portion 3b. With this configuration, the amount of reflected light Rl that reaches the part P of the predetermined portion of the switch knob 1 can be optimally increased by the reflection surface 3d, and the entire illumination portion 4 of the switch knob 1 can be illuminated with a more uniform brightness.

[0033] According to this embodiment, the arm 3c extending from the pressure-receiving surface 3a can have an orthogonal arm 3c1 extending between the wall 3b and a part of the predetermined part of the switch knob 1 illuminated by the reflected light Rl by the wall 3b, perpendicular to an imaginary line connecting the light source 6 and the part P of the predetermined part of the switch knob 1 illuminated by the reflected light Rl by the wall 3b. With this configuration, the wall 3b can be reinforced by the orthogonal arm 3c1 extending from the pressure-receiving surface 3a, and the orthogonal arm 3c1 does not obstruct the optical path of the reflected light Rl.

[0034] According to this embodiment, a pair of arms 3c are provided. Each wall 3b of the pair of arms 3c can illuminate a portion P of a predetermined portion of the switch knob 1 line-symmetrically from both sides with reflected light Rl. With this configuration, the amount of reflected light Rl that reaches the portion P of the predetermined portion of the switch knob 1 can be optimally increased line-symmetrically, and the entire illumination unit 4 of the switch knob 1 can be illuminated with more uniform brightness.

[0035] According to this embodiment, the wall portion 3b can be made of a transparent material. With this configuration, the amount of reflected light Rl that reaches the part P of the predetermined portion of the switch knob 1 can be increased by the wall portion 3b made of a transparent material, and the entire illumination portion 4 of the switch knob 1 can be illuminated with more uniform brightness.

[0036] According to this embodiment, the wall 3b can be made of a transparent plastic material, a mirror-polished metal material, an aluminum-deposited material, or a material coated with high-brightness paint. With this configuration, the amount of reflected light Rl that reaches the part P of the predetermined part of the switch knob 1 can be increased by the wall 3b made of various materials, and the entire illumination part 4 of the switch knob 1 can be illuminated with a more uniform brightness.

[0037] According to this embodiment, the wall portion 3b can be molded integrally with the push boss 3. With this configuration, the wall portion 3b is molded integrally with the push boss 3, which can provide reinforcement and facilitates manufacturing.

[0038] According to this embodiment, the wall portion 3b can have a shape in which the angle of incidence of the light emitted from the light source 6 exceeds the critical angle at which the light is reflected. If the angle of incidence of the light emitted from the light source 6 does not exceed the critical angle at which the light is reflected, reflected light Rl cannot be obtained. In contrast, with this configuration, the amount of reflected light Rl that reaches the part P of the predetermined portion of the switch knob 1 can be ensured, and the entire illumination portion 4 of the switch knob 1 can be illuminated with a more uniform brightness.

[0039] According to this embodiment, the reflecting surface 3d, which reflects light emitted from the light source 6 on the wall portion 3b and reaches the wall portion 3b to illuminate a predetermined portion P of the switch knob 1 with reflected light Rl, can have an area that makes the amount of light of the predetermined portion P of the switch knob 1 illuminated by the reflected light Rl by the wall portion 3b equal to the amount of light of other portions of the switch knob 1 other than the predetermined portion P that are directly illuminated by light emitted from the light source 6. With this configuration, the entire illumination portion 4 of the switch knob 1 can be illuminated evenly with more uniform brightness.

[0040] According to this embodiment, the electronic device 100 includes the illumination structure 10 for the switch knob 1 and the operation panel 101. With this configuration, the amount of light reaching a predetermined portion of the switch knob 1 can be increased, and the entire illumination unit 4 of the switch knob 1 can be illuminated with more uniform brightness. [others] The above-described components include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the above-described configurations can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations are possible without departing from the scope of the present invention. [Explanation of symbols]

[0041] 1 Switch knob 2 Tactile Switch 2a Push part 3 Push boss 3a Pressure-receiving surface part 3a1 Front end part 3a2 Thick-walled part 3b Wall part 3c Arm part 3c1 Orthogonal arm part 4 Lighting part 6 Light source 10 Lighting structure 11 Substrate 100 Electronic device 101 Operation panel 101a Surface part 102 Translucent part

Claims

1. A tactile switch that converts the user's pressing reaction into an electrical signal; a switch knob that is disposed on a surface portion separated from a substrate on which the tactile switch is disposed and corresponds to the tactile switch; a light source disposed on the board and configured to illuminate a predetermined portion of the switch knob on the surface portion; a push boss disposed between the tact switch and the switch knob, for transmitting a push response of the user from the switch knob to the tact switch; Equipped with The push boss has a pressure-receiving surface portion that receives a pressing force from the switch knob, and a wall portion that is provided at a position different from the pressure-receiving surface portion, The illumination structure for the switch knob includes an arm extending from the pressure-receiving surface portion, the arm extending perpendicular to a virtual straight line connecting the light source and a part of the specified portion of the switch knob that is illuminated by light reflected by the wall portion, between the part of the specified portion of the switch knob that is illuminated by light reflected by the wall portion and the wall portion.

2. The switch knob illumination structure according to claim 1 , wherein the wall portion has a reflective surface that is parallel to a straight line connecting a portion illuminated by the light source and the light source.

3. 3. The switch knob lighting structure according to claim 1, wherein a reflective surface in the wall portion reflects light emitted from the light source and reaching the wall portion to illuminate a portion of a predetermined portion of the switch knob with the reflected light, the reflective surface having an area such that an amount of light of the portion of the predetermined portion of the switch knob illuminated by the reflected light from the wall portion is equal to an amount of light of another portion of the predetermined portion of the switch knob directly illuminated by the light emitted from the light source.

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