JP5889956B2 - Lighting structure and portable computer - Google Patents

Description

  The present invention relates to an illumination structure for illuminating the outside from an opening of a wall, and more particularly to an illumination structure for illuminating a direction close to the surface of the wall while reducing the amount of light guide protruding from the surface of the wall.

  Patent Document 1 discloses a notebook personal computer (hereinafter referred to as a notebook PC) provided with an illumination device (keyboard light) for illuminating the keyboard surface. The illuminating device is realized by an LED holder that houses an LED. The upper edge of the display device extends like a ridge with respect to the surface of the display device, and by attaching the lighting device to the upper edge, the light beam from the LED holder can irradiate the keyboard arranged immediately below. Yes.

  In recent portable computers, a so-called flat design method has been adopted in which the peripheral surface of the display device and the surface of the display device are present on the same plane. In this case, since there is no structure such as a bag on the surface of the display device, it is not possible to employ a keyboard / light having a structure as disclosed in Patent Document 1. In addition, a method of supporting the LED holder with a spring structure and popping it out from the inside of the housing or pushing it into the housing according to the opening / closing of the lid of the notebook PC can be considered, but this is not preferable because the number of parts increases.

  Patent document 2 discloses the light irradiation apparatus comprised with the light source and the light-guide plate. The light guide plate is configured to multiple-reflect light rays incident from the light source and emit the light from between the vertical direction and the horizontal direction with respect to the bottom surface. Patent document 3 discloses the illuminating device which embeds in a wall surface and irradiates a floor. When the light emitted from the fluorescent lamp travels while repeating total reflection inside the wedge-shaped light guide, the illuminating device of the same document gradually emits light obliquely downward when the critical angle is exceeded. It has come to go. The document describes that the emitted light is emitted at an emission angle of 65 ° ± 10 ° with respect to the normal to the wall surface.

Japanese Patent Laid-Open No. 2001-22470 Japanese Patent No. 3982174 JP-A-8-17209

  The method of Patent Document 3 is not suitable for mounting around the display because a long light guide is required to use repetition of total reflection. In addition, since it does not contain light rays that have an emission angle (refraction angle) that is large enough to illuminate an area close to the keyboard display, it cannot be used for keyboard lights. When the light guide plate described in Patent Document 2 is turned upside down and used for a keyboard light, the light guide plate needs to have a length for performing multiple reflections between the front surface F and the back surface R. In addition, since it does not include a light beam having an emission angle that is large enough to irradiate the entire keyboard, it is not suitable for application to a keyboard light for the same reason as in Patent Document 3.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an illumination structure suitable for a keyboard light for a portable computer. It is another object of the present invention to provide an illumination structure that can irradiate a direction close to the surface of the edge frame by reducing the amount of projection of the light guide from the surface of the edge frame. A further object of the present invention is to provide a portable computer in which such an illumination structure is applied to a keyboard light.

  A first aspect of the illumination structure of the present invention is a portable computer comprising a light guide, a system housing having a keyboard mounted on the surface, and a light source disposed on the inner side of the edge frame of the display housing connected by a hinge. Provide lighting structure that can be mounted on The light guide includes an incident surface on which light from the light source is incident, an output surface in which at least a part of the light source protrudes outside the surface of the edge frame, a bottom surface that communicates with the incident surface and the output surface, the incident surface, and the output surface. And a bottom surface in contact with. The light exit surface can refract the light beam directly incident on the region where the light exit surface protrudes from the light source at a refraction angle within a predetermined range from the maximum refraction angle and emit the light to the keyboard.

  The exit surface can be formed as a curve in a cross section cut along a plane perpendicular to the bottom surface including the optical axis of the light source, such that the incident angle of light rays parallel to the optical axis of the light source becomes smaller as it approaches the bottom surface. The emission surface may be a flat surface, but if it is a curved surface, the light collection efficiency of the light emitted from the light source can be increased. At this time, the cross section of the exit surface can be formed by a cubic curve or an arc having a predetermined radius and center angle. If the light source is set so that the light beam traveling on the optical axis of the light source enters the position that protrudes most from the surface of the edge frame in the curved surface, or the shape of the exit surface is selected, the light source directly goes to the exit surface. The incident direct light beam can be refracted and emitted in a direction in which it is uniformly dispersed from the maximum refraction angle to a predetermined refraction angle range. At this time, the tangent plane with respect to the position of the exit surface most protruding from the surface of the wall can be set to be parallel to the surface of the edge frame.

  By tilting the optical axis of the light source with respect to the normal of the edge frame, more light rays that are directly incident on the emission surface from the light source can be emitted in a direction closer to the surface of the edge frame. The facing surface can reflect the light directly incident from the light source only once and enter the light exiting surface. In a cross section cut along a plane perpendicular to the bottom surface including the optical axis of the light source, the incident angle with respect to the position on the emission surface of the light beam passing through the optical axis parallel to the bottom surface passing through the center position of the light source becomes a critical angle. Can be configured.

  In the cross section, the incident angle of the light beam directly incident on the exit surface from the light source is changed from the maximum refraction angle to the refraction angle in a predetermined range as the radiation position of the light source approaches the bottom surface direction from the center position of the light source. Can be configured. A light beam emitted from a position away from the bottom surface from the center position of the light source and directly entering the position on the output surface can be totally reflected. The refraction angle of light emitted from the critical position can be in the range of 45 degrees or more with respect to the maximum refraction angle.

  According to the present invention, an illumination structure suitable for a keyboard light of a portable computer can be provided. Further, according to the present invention, it is possible to provide an illumination structure that can irradiate a direction close to the surface of the edge frame by reducing the projection amount of the light guide from the surface of the edge frame. Further, according to the present invention, a portable computer in which such a lighting structure is applied to a keyboard light can be provided.

It is a figure explaining the illumination assembly applied to the illumination structure concerning this Embodiment. It is a figure explaining the behavior of the light ray in the interface surface of air and acrylic. It is a figure which shows the incident angle (alpha) at the time of the parallel ray irradiated to the incident surface injecting into an opposing surface for every position. FIG. 3 shows a typical ray path in a lighting assembly. It is sectional drawing which shows the illumination structure which attaches an illumination assembly to a wall and irradiates the area | region close | similar to the wall of an irradiation surface from opening of a wall. It is a figure explaining the method of determining the inclination-angle of an optical axis. It is a figure which shows the other example of the cross-sectional shape of a light guide. FIG. 6 illustrates an example of applying a lighting assembly to a keyboard light.

[Lighting assembly]
FIG. 1 is a diagram illustrating a lighting assembly applied to the lighting structure according to the present embodiment. FIG. 1A is a perspective view of the illumination assembly 10 as viewed obliquely from above, FIG. 1B is a plan view seen from above, and FIG. 1C is a view taken along the line AA in FIG. 2 is a cross-sectional view taken along a plane that includes the optical axis of the light source 23 and that is centered in the width W direction and perpendicular to the bottom surface. The light guide 11 has a shape shown in FIG. 1C even if it is cut at any location on a plane parallel to the cross section taken along the line AA.

  The light guide 11 is integrally formed by a method such as compression molding or injection molding using an acrylic (PMMA) resin having a high light transmittance as a material. The light guide 11 includes an incident surface 13, a bottom surface 12, a facing surface 50, and side surfaces 19 and 21. The incident surface 13 and the side surfaces 19 and 21 are planes perpendicular to the bottom surface 12. As an example, the light guide 11 has a width W of 12 mm, a length L of 6 mm, and a height H of 2.5 mm. The cross-sectional shape of the facing surface 50 can be formed by adopting a cubic curve, combining arcs with a predetermined radius and center angle, and further combining straight lines with them.

  A light emitting diode is adopted as the light source 23. As an example, the light emitting surface of the light source 23 is configured such that a light beam is emitted in a conical shape from a radiation surface having a diameter of 2 mm through the center and at an angle of 60 degrees with respect to an optical axis perpendicular to the radiation surface. Light emitted from the light source 23 enters the light guide 11 through the incident surface 13. A region facing the incident surface 13 in the facing surface 50 is referred to as a tip portion. On the facing surface 50, an exit surface 51 can be defined at the tip, and a reflecting surface 53 can be defined between the exit surface 51 and the entrance surface 13. The emission surface 51 is an area where the light emitted from the light source 23 is emitted from the light guide 11 into the air.

  On the exit surface 51, the light incident from the entrance surface 13 is totally reflected once at the inside and the reflecting surface 53 (hereinafter, the first total reflection is referred to as primary total reflection). Total reflection of the totally reflected light beam is called secondary total reflection.) The light beam enters. A light ray that is incident on the facing surface 50 without being totally reflected once inside the light guide 11 is called a direct light beam, and a light beam that is totally reflected once or a plurality of times on the facing surface 50 is called a reflected light beam. . Of the direct light and the reflected light, the light incident on the facing surface 50 at an incident angle less than the critical angle is transmitted through the facing surface 50 and emitted into the air, and the light incident at an incident angle exceeding the critical angle is opposed to the facing surface. Total reflection at 50.

  Therefore, if the exit surface 51 is defined as the region of the light guide from which the light from the light source 23 exits, the range will differ for each incident light beam. In the present specification, the region of the facing surface 50 at the distal end portion of the light guide 11 from which any direct light or reflected light emitted from the light source 23 is emitted is referred to as an emission surface 51. In this specification, since it is not necessary about the behavior of the scattered light which arises inside the light guide 11, description is abbreviate | omitted.

  The bottom surface 12 of the light guide 11 is provided with an absorption layer 25 disposed in close contact with the bottom surface 12 of the light guide 11 so as not to form an air layer. The bottom surface 27 of the absorbing layer 25 corresponds to the bottom surface of the lighting assembly 10 and provides a mounting surface for the lighting assembly 10. The absorption layer 25 is formed of a material close to the refractive index of acrylic so that incident light is not totally reflected by the bottom surface 12 of the light guide 11. Therefore, light incident on the bottom surface 12 at an incident angle exceeding the critical angle enters the absorption layer 25 without being totally reflected.

  In this embodiment, a black translucent material is used for the absorption layer 25 to absorb the light incident on the absorption layer 25, and the incident light is totally reflected at the boundary between the absorption layer 25 and the air. No progress to 50. The absorption layer 25 can be formed by applying black ink to the bottom surface 12 of the light guide 11 by screen printing. However, if the three conditions, that is, an air layer is not sandwiched between the bottom surface 12 and the absorption layer 25, incident light can be efficiently absorbed, and the refractive index is close to that of acrylic, the absorption layer 25 is It can be formed by other materials molded by two colors of black resin and transparent resin or by other methods.

[Refraction angle and reflection angle]
FIG. 2 is a diagram for explaining the behavior of light rays inside acrylic in contact with air. The refractive index is about 1.5 for acrylic 61 and 1 for air. In this case, according to Snell's law, the critical angle θm of light incident on the boundary 63 between the acrylic 61 and the air from the inside of the acrylic 61 is 42 degrees. FIG. 2A shows a state in which a light beam having an incident angle α changed from 0 degree to the critical angle θm is incident on the boundary 61. While the incident angle α is less than the critical angle θm, incident light is emitted from the acrylic 61 into the air at a refraction angle β or an emission angle β (β> α). The relationship between the incident angle α and the refraction angle β at this time is shown in FIG.

  From FIG. 2 (C), the refraction angle β increases almost in proportion to the incident angle α until the incident angle α is about 35 degrees, but the incident angle α exceeds 35 degrees (the refraction angle is 60 degrees). From the above, it can be seen that the rate of increase of the refraction angle β increases with respect to the rate of increase of the incident angle, and the refraction angle β increases rapidly as the critical angle θm is approached. The refraction angle β is maximized immediately before the incident angle α reaches the critical angle θm. The incident angle at this time is called a transmission maximum incident angle, and the refraction angle is called a maximum refraction angle.

  In the illumination structure of the present embodiment, which will be described later, as many rays as possible enter the exit surface 51 at an incident angle α in the range of 35 degrees ≦ α <θm at each incident position, and the incident angle of each ray is as much as possible. The direction of the optical axis of the light source 23, the shape of the emission surface 51, the shape of the reflection surface 53, and the like are determined so as to be evenly dispersed at the positions. FIG. 2B shows a state where a light ray incident at an incident angle α exceeding the critical angle θm is totally reflected at the boundary 63 at a reflection angle γ. In the case of total reflection, light rays travel so that the incident angle α and the reflection angle γ coincide.

[An incident angle with respect to the opposing surface of parallel rays]
In FIG. 3, when a surface light source that radiates parallel rays is arranged on the entire incident surface 13, the incident angle α when the parallel rays are incident on the opposing surface 50 is determined for each position of the opposing surface 50 corresponding to the bottom surface 12. FIG. Here, an example in which the entire facing surface 50 is formed by a cubic curve will be described. The incident angle α with respect to the opposing surface 50 decreases as the position of the opposing surface 50 increases from the incident surface 13, and reaches the critical angle θm at a position corresponding to the length P of the bottom surface 12 measured from the exit surface 13 side. Further, the incident angle α decreases as it approaches the front further, and the incident angle α becomes zero at the position of the length L of the bottom surface 12 corresponding to the most tip of the facing surface 50. Therefore, the opposing surface 50 acts to totally reflect light rays parallel to the bottom surface 12 to a position corresponding to the length P of the bottom surface and to transmit light from a length P to a position corresponding to the length L.

  Therefore, the facing surface 50 for the light ray parallel to the bottom surface 12 becomes the reflecting surface 53 from the length 0 to the position corresponding to the length P, and becomes the emitting surface 51 from the length P to the position corresponding to the length L. . Here, a cubic curve has been described as an example. However, in the case of a continuous curve that has no inflection point and bulges outward as shown in the figure, the positions of the critical angles are different, but the relationship between the distance and the incident angle is the same. Become a trend. The actual light source 23 does not irradiate the incident surface 13 only with light rays parallel to the optical axis, and the radiation surface of the light source 23 is smaller than the area of the incident surface 13 and extends in a conical beam shape of about 60 degrees. Therefore, light rays are incident on the opposing surface 50 at various incident angles α.

[Light path of lighting assembly]
FIG. 4 is a diagram illustrating a typical ray path in the illumination assembly 10. Here, in the light guide having the size shown in FIG. 1, the tip of the facing surface 50 is formed by an arc having a cross section of a radius of 1.5 mm and a central angle of 60 degrees, and the other region having a radius of 9 mm and a central angle. Is formed by a 30 degree arc. FIG. 4 shows a cross section taken along line AA in FIG. The light source 23 emits conical beam-like light with a spread of 60 degrees from the radiation surface perpendicular to the bottom surface 12 to the incident surface 13, and the vertical extension of the radiation light is indicated by light rays 101 and 109 in the figure, A range in the vertical direction of the radiation surface of the light source 23 is indicated by a position S1 and a position S3.

  A light beam 106 travels on an optical axis 100 that passes through the center position S2 of the light source and is perpendicular to the radiation surface. In the optical axis 100, the incident surface 13 and the radiation surface of the light source 23 are adjusted so as to be parallel to the bottom surface 12. In addition, the incident angle of the light beam 106 with respect to the tangent 131 at the position P5 on the facing surface 50 on which the light beam 106 is incident is set in the height direction of the light source 23 so as to coincide with the critical angle.

  First, the path of the direct light beam that is emitted from between the position S1 and the position S3 of the light source and enters the position P5 on the opposing surface will be described. In the figure, light rays 105, 106, and 107 are shown as typical light rays in this case. The direct light beam that is emitted from the position S3 slightly from the position S2 of the light source and is incident on the position P5 is transmitted, and is refracted at the maximum refraction angle as shown in FIG. The direct light beam emitted from between the positions S2 and S3 of the light source and incident on the position P5 has a smaller incident angle as the radiation position approaches the position S3, and the light beam 121 is indicated by an arrow A with the position P5 as the center. The light is emitted in the direction rotated clockwise.

  A direct ray emitted from a position slightly closer to the position S1 than the position S2 of the light source is totally reflected at a reflection angle close to the critical angle and enters the bottom surface 12. The direct light beam that is radiated from between the position S2 and the position S1 of the light source and is incident on the position P5 has a larger incident angle and a larger reflection angle as the radiation position approaches the position S1. Is incident on a position on the bottom surface 12 so as to approach the position P8 to be contacted. Since the light ray incident on the bottom surface 12 is almost absorbed by the absorption layer 25, almost no total reflection occurs at the bottom surface 27.

  Next, a path of light rays emitted from between the positions S1 and S3 of the light source and parallel to the optical axis 100 will be described. As can be inferred from FIG. 3A, the light beam parallel to the optical axis 100 radiated from between the position S1 and the position S2 of the light source has an incident angle exceeding the critical angle, so that the primary total between the position P4 and the position P5. The light is reflected and enters the bottom surface 12 or is secondarily totally reflected at the tip of the facing surface 50 and enters the bottom surface 12. The figure shows a state in which the light beam 104 undergoes primary total reflection at the position P4 and enters the bottom surface 12. All the rays parallel to the optical axis 100 emitted from between the positions S2 and S3 of the light source are transmitted because the incident angle is smaller than the critical angle.

  A light ray parallel to the optical axis 100 emitted from a position slightly from the position S3 than the position S2 of the light source is incident on the opposing surface 50 at the maximum transmission incident angle and is transmitted and maximally refracted, as is apparent from FIG. Refracts at the corner. Then, as the radiation position approaches the position S3 or as the incident position approaches the position P6, the incident angle and the refraction angle become smaller, and the light is refracted in a direction away from the tangent line at each incident position. In the figure, a state in which the light beam 108 is transmitted at the position P6 and is emitted as the light beam 123 is shown.

  In this example, all light rays radiated from between the positions S1 and S2 of the light source and incident between the positions P5 and P6 on the opposing surface are totally totally reflected. A light beam emitted from between the position S2 and the position S3 of the light source and incident between the position P4 and the position P5 on the opposing surface is transmitted and refracted because the incident angle is smaller than the critical angle. The refraction angle of the transmitted light continuously changes depending on each radiation position from the maximum refraction angle to a refraction angle in a range smaller by a predetermined range depending on the incident angle at each incident position.

  Next, a typical direct ray path radiated from the light source 23 and incident on a position other than the range from the position P4 to the position P6 on the facing surface will be described. The illumination assembly 10 has an optical shape so that the light beam 101 is totally reflected at the position P1 of the facing surface 50. Accordingly, the range from the position P1 to the position P0 where the opposing surface 50 and the incident surface 13 communicate with each other does not function optically. The light beam 109 is directly incident on the bottom surface 12, but is absorbed by the absorption layer 25 without being totally reflected on the bottom surface 12.

  In this example, all direct rays incident between the light source 23 and the positions P1 to P4 of the facing surface are totally reflected by the facing surface 50. In the figure, the light beam 101 is totally reflected at the position P1 and incident on the bottom surface 12, and the light beam 102 is totally reflected at the position P2 and incident on the position P7 and transmitted therethrough. The direction of the outgoing light beam 102 rotates to the right of the tangent line 131. The light beam 103 undergoes primary total reflection at the position P 3, undergoes secondary total reflection between the positions P 6 and P 7, and enters the bottom surface 12. Thus, the reflected light beam that has undergone primary total reflection between the position P1 and the position P4 includes light that is incident and transmitted between the position P6 and the position P8. Of the light rays that have been primarily totally reflected at the facing surface 50, most of the light rays that are secondarily totally reflected at the facing surface 50 are incident on the bottom surface 12 and are not emitted.

  In this example, the light beam emitted from the light source 23 and incident between the positions P6 and P8 on the opposing surface is primarily totally reflected and enters or passes through the bottom surface 12. The direct light beam transmitted between the position P6 and the position P8 includes a light beam that is refracted in a direction rotated in the left direction with respect to the tangent 131 (a direction approaching the light guide 11) like the light beam 102. As described above, most of the direct light rays emitted from the light source 23 and incident on the front end portion of the opposing surface 50 have a refraction angle in a range of about 60 degrees from the maximum refraction angle, and a direction almost close to a tangent at the incident position of each light ray. From about 30 degrees to the tangential line, changing the direction evenly.

  The above is a description of a typical light beam path of the illumination assembly 10. The first feature of the illumination assembly 10 is that an area formed by a curved surface centered on the position P5 on the optical axis 100 is formed. The light beam of various paths incident thereon is transmitted and refracted uniformly from the maximum refraction angle to a predetermined refraction angle of about 60 degrees to be emitted. The predetermined refraction angle can be about 45 degrees. The second feature is that light rays emitted from the facing surface 50 are suppressed by suppressing total reflection at the bottom surface 12 by the absorption layer 25. The third feature is that the opposing surface 50 in the range between the position P1 and the position P4 on the opposing surface 50 first totally reflects the light incident thereon, and part of the light enters the range from the position P5 to the position P8. It is in the point of letting it pass.

  The light guide 11 irradiates the tip portion in the downward direction or the direction of the bottom surface 12 using the facing surface 50 that is refracted at a refraction angle ranging from the maximum refraction angle to about 60 degrees. It is a structure suitable for. And since multiple total reflection is not utilized between the opposing surface 50 and the bottom face 12, the length L of a light guide is not subject to optical restrictions. Therefore, when it is not necessary to use the reflected light from the facing surface 50 for illumination, the length L can be shortened to a physically possible range. Therefore, the illumination assembly 10 has an advantageous configuration when applied to a small electronic device having a flat wall on which a large protrusion cannot be formed.

[Lighting structure]
Next, referring to the cross-sectional view of FIG. 5, an illumination structure that irradiates a region near the wall of the irradiation surface 203 by attaching the illumination assembly 10 to the wall will be described. The wall 201 extends vertically upward from the irradiation surface 203. The range irradiated by the illumination assembly 10 is indicated by a distance L2 from the wall. The area of the irradiation surface 203 from the wall position to the distance L2 is referred to as a required irradiation area. The illumination assembly 10 shows the same cross section as in FIG. 4, but the position Q1 where the light beam 106 traveling on the optical axis 100 of the light source 23 is incident on the facing surface 50 is slightly different from the position P5 in FIG. Yes.

  An opening 202 is formed in the wall 201 at a position where the lighting assembly 10 is fixed. The wall 201 is slightly inwardly inclined at the position 209 and further communicates with the mounting portion 207 inclined at an inclination angle θ with respect to the irradiation surface 203. The lighting assembly 10 has a bottom surface 27 attached to a mounting portion 207. Since the bottom surface 27 and the optical axis 100 are parallel, the optical axis 100 is inclined with respect to the irradiation surface 203 at an inclination angle θ. The reason why the wall 201 is slightly inclined toward the inner side of the wall at the position 209 is that the light emitted from the emission surface formed at the tip portion of the light guide 11 is effectively used for irradiation of the irradiation surface 203. is there.

  The reason why the optical axis 100 is inclined with respect to the irradiation surface 203 is to irradiate many light rays in a region from the region near the wall 201 of the irradiation surface 203 to about 30 degrees centering on the light guide. is there. That is, in the light path of FIG. 4, a light beam incident at a maximum transmission angle at a position close to the position P8 is emitted at a maximum refraction angle or a refraction angle in the vicinity thereof, but such a light beam is limited to a reflected light beam. Since the direct light beam has a small incident angle, the required irradiation region can be illuminated with sufficient illuminance by inclining the optical axis 100 in order to be emitted in a direction away from the tangent line. Here, in order to make effective use of light rays emitted from the radiation surface of the light source 23 that spreads in area, the inclination angle θ is set to 45 degrees that is slightly larger than the critical angle θm. The reason will be described later.

  A part of the front end portion of the facing surface 50 protrudes slightly outward from the wall surface 205 through the opening 202. The position Q5 of the facing surface 50 where the light beam 106 traveling on the optical axis 100 is incident is set to the position of the facing surface of the light source 23 such that the position Q5 of the facing surface protrudes most outward from the wall surface 205. ing. The distance L1 between the position Q5 and the wall surface 205 is set to about 2 mm. The interval L1 can be determined based on the illuminance required for the area near the wall 201 of the effective irradiation area, the luminance of the light source, and the like. The tangent 221 at the position Q5 is set to be parallel to the wall surface 205 or perpendicular to the irradiation surface 203.

  In this illumination structure, the area between the position Q5 and the position Q8 on the facing surface is an emission surface that effectively irradiates the required irradiation region. Between the position Q5 and the position Q4 of the opposing surface, the light beam incident on the position where the tangent line at each position falls within the range of the distance L2 on the irradiation surface 203 can irradiate the required irradiation region. Therefore, the opposing surface in the vicinity of the position Q5 between the position Q4 and the position Q5 is also an effective emission surface.

  The direct ray or the first-order totally reflected ray incident from the light source 23 at the representative positions Q5 and Q6 in the range of the emission surface is continuous from the maximum refraction angle to about 60 degrees with respect to the tangent 221 or tangent 223. It is possible to irradiate the required irradiation region with uniform illuminance by emitting at a refraction angle. The direct ray or the reflected ray incident on the range from the position Q5 to the position Q8 also includes a ray 225 emitted in the direction of the wall surface 205 from the tangential plane including the tangent 221 to the position Q5 most protruding from the emission surface.

  In FIG. 5, an example in which the light guide 11 and the light source 23 are arranged inside the wall 201 and a part of the light guide 11 is arranged outside the wall surface 205 using the opening 202 formed in the wall. Although shown, the present invention is not limited to such an arrangement method. For example, using a notch formed at the end of the wall, or placing a light guide and a light source in a recess formed in the wall so that at least a portion of the light guide protrudes from the wall surface. Can be arranged.

[Determination method of tilt angle θ]
Next, the reason why the inclination angle θ of the optical axis 100 with respect to the irradiation surface 203 is set to 45 degrees and 3 degrees larger than the critical angle will be described with reference to FIG. FIG. 6A shows a cross section of the lighting assembly 10 cut along a plane parallel to the bottom surface and including the optical axis. The line 231 is formed by cutting a tangential plane 231 including the tangent 221 in FIG. 6B is a cross-sectional view taken along a plane that is perpendicular to the bottom surface and includes the optical axis, as viewed in the direction of arrows BB in FIG. 6A. FIG. 6C is a cross-sectional view taken along a plane that is perpendicular to the bottom surface and includes the light beam 16c in the direction of arrows CC in FIG. In FIG. 6A, the light beams 106a, 106, and 106c travel on the same plane and enter the positions Q1a, Q1, and Q1c on the opposing surfaces that are in contact with the tangential plane 231 respectively.

  In FIG. 6C, a tangent 231c shows a state in which the tangent plane 231 is cut, and the tangent 231c is rotated slightly to the left from the tangent 221 cut in the tangent plane 231 in FIG. That is, at the position Q1c on the facing surface, the incident angle θc of the light beam 106c traveling on the plane including the optical axis and parallel to the bottom surface is the incident angle θc of the light beam 106 traveling on the optical axis and entering the position Q1 on the facing surface. It becomes smaller than the incident angle θ. The same applies to the position Q1a where the light beam 106a is incident.

  In FIG. 6B, the angle of the tangent 221 with respect to the normal 251 corresponds to an inclination angle θ of 45 degrees. Therefore, the light beam traveling on the optical axis 100 cannot be effectively used because it undergoes primary total reflection at the position Q1 of the opposing surface. However, since the emission surface of the light source 23 has an area spread in the vertical direction, the light beam 105 and the light beam 107 are inclined by about 8 degrees with respect to the optical axis 100, respectively. Therefore, the light beam radiated from the position below the position S5 on the radiation surface passes through the position Q1 on the opposite surface.

  On the other hand, at the position Q1c where the light beam 106c is incident on the tangential plane 231, the incident surface θc of the light beam 106c is inclined because the cut surface of the CC arrow is inclined with respect to the cut surface of the BB arrow. It is about 5 degrees smaller than the angle θ. Therefore, the light beam radiated from the position below the position S6 on the radiation surface passes through the position Q1c on the opposite surface. The light beam for the position Q1a is transmitted in the same manner. Therefore, among the light rays incident on the position of the opposing surface that is in contact with the tangential plane 231 including the positions Q1a, Q1, and Q1c, the light passes through the optical axis and its vicinity on the plane of FIG. Light incident on both sides is not transmitted.

  However, since light rays emitted from a radiation position below the optical axis and incident between a position separated by a predetermined distance from the position Q1 and the position Q1a or the position Q1c are transmitted, the incident light of the light source as a whole is transmitted. The utilization rate is getting higher. In FIG. 6C, light from the region of the radiation surface above the position S6 is not available, but the direct light beam radiated from that position is totally reflected at the position in contact with the tangential plane 231. This is an area that cannot be used for outgoing light. Thus, by setting the inclination angle θ to 45 degrees, the amount of light traveling in parallel with the tangent 221 is increased to increase the incident efficiency, and the interval L1 in FIG. Can be minimized.

[Other examples of light guide]
FIG. 7 is a cross-sectional view showing another example of the cross-sectional shape of the light guide. 7A to 7D each show a cross section at a position corresponding to the arrow AA in FIG. 1, and further, an absorption layer is provided on the bottom surface. In the light guide of FIG. 7A, the opposing surface 301 is a reflective surface formed by a planar emission surface 303 in the range from the position R1 to the position R3 and a cubic curve or an arc having a predetermined radius and central angle. 305 is provided. The inclination of the exit surface 303 with respect to the optical axis of the light source 23 is set so that the light beam 307 traveling on the optical axis is incident on the position R2 of the exit surface 303 at a critical angle. In this case, light rays emitted from between the positions S1 to S3 of the light source in parallel with the optical axis are not transmitted, but light rays incident at an angle smaller than the critical angle are transmitted. The refraction angle is determined by the incident position on the exit surface 303 and the emission position of the light source, but it is possible to obtain the exit light having a refraction angle that is evenly distributed from the maximum refraction angle to a predetermined range.

  However, in this case, the light beam that is primarily totally reflected by the reflecting surface 305 and incident on the exit surface 303 is secondarily totally reflected by the exit surface 303 and is incident on the bottom surface 305. descend. In order to compensate for this, a plane perpendicular to the bottom surface 305 from the position R2 can be formed as shown by the dotted line. When the emission surface 303 is formed so that planes inclined at various angles with respect to the optical axis are adjacent to each other, the most efficient shape shown in FIG. 4 is reached.

  FIG. 7B shows an example in which the emission surface 313 has the same shape as the emission surface of FIG. 4 and the reflection surface 315 is formed in a planar shape. In FIG. 7C, the region 321 on the opposite surface including the emission surface has the same shape as that in FIG. 4, but the region 323 near the light source is curved toward the bottom surface 325 as it approaches the light source. In the region 323, the incident angle and the reflection angle of incident light are increased so that the first total reflected light can enter the exit surface as much as possible. FIG. 7D shows that when the illumination assembly is attached with the optical axis 337 inclined at an inclination angle θ with respect to the wall as shown in FIG. 5, the light guide itself can be attached to the wall without being inclined. It is a thing. In FIG. 7D, a plane 331 that intersects the optical axis at an inclination angle θ of FIG. 5 and a region 333 that connects the plane 331 and the incident surface 335 are formed.

[Example of lighting assembly application]
FIG. 8 is a diagram illustrating an example in which the lighting assembly 10 is applied to a notebook PC. The notebook PC 400 is supported so that the display housing 401 is coupled to the system housing 405 by a hinge 403 and can be opened and closed. A display housing 401 accommodates a liquid crystal display (LCD) 409. A keyboard 407 is mounted on the surface of the system housing 405. The periphery of the LCD 409 is surrounded by edge frames 411a to 411d. The surfaces of the edge frames 411a to 411d and the surface of the LCD 409 exist on the same plane.

  A small opening is formed in the top edge frame 411b, and the lighting assembly 10 is mounted inside. The lighting assembly 10 is attached so that the optical axis is inclined at an angle θ with respect to the surface of the edge frame 411b with the wall 201 of FIG. 5 corresponding to the edge frame 411b. Since the lighting assembly 10 can suppress the height of the light guide 11 protruding from the opening to about 2 mm, it can be applied to a design in which the surface of the edge frames 411a to 411d and the surface of the LCD are flush with each other. It becomes possible. In a state where the display housing 401 is opened, the light beam emitted from the emission surface of the illumination assembly 10 can irradiate the keyboard 407.

  The application example of the lighting assembly 10 is not limited to a notebook PC, but may be applied to a wide range of lighting such as an operation surface of an electronic device such as an electronic dictionary or a smartphone, lighting inside or outside a car, and indoor lighting. Can do. Further, as shown in FIG. 5, the relationship between the illumination assembly and the irradiation surface is not necessarily limited to the case where the irradiation surface is disposed below, and the irradiation surface is disposed on the upper side or the left and right sides. The outgoing light from the light guide can also be directed in those directions.

  Although the present invention has been described with the specific embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and is known so far as long as the effects of the present invention are achieved. It goes without saying that any configuration can be adopted.

DESCRIPTION OF SYMBOLS 10 ... Illumination assembly 11 ... Light guide 12 ... Bottom surface 13 of light guide ... Incident surface 23 ... Light source 25 ... Absorbing layer 27 ... Bottom surface 50 of illumination assembly ... Opposite surface 51 ... Output surface 53 ... Reflective surface 100 ... Optical axis 400 ... Portable computer

Claims (11)

An illumination structure for illuminating a keyboard of a portable computer equipped with a display ,
A light guide;
A light source disposed on the inner side of the surface of the edge frame constituting the casing of the portable computer , including the surface of the display ;
The light guide is
An incident surface on which light from the light source is incident;
An emission surface in which at least a part of the region protrudes outside the surface of the edge frame from an opening formed in the edge frame ;
A bottom surface communicating with the entrance surface and the exit surface;
A reflective surface that is disposed at a position facing the bottom surface and reflects the light that is directly incident from the light source to be incident on the exit surface;
An illumination structure capable of refracting a part of a light beam directly incident from the light source into a region where the exit surface protrudes from the exit surface with a refraction angle within a predetermined range from a maximum refraction angle to the keyboard.   In a cross section cut along a plane perpendicular to the bottom surface including the optical axis of the light source, the exit surface is formed with a curve that reduces the incident angle of light rays parallel to the optical axis of the light source as it approaches the bottom surface. The lighting structure according to claim 1.   3. The illumination structure according to claim 2, wherein, in the cross section, an incident angle with respect to a position on the emission surface of a light beam passing through an optical axis parallel to the bottom surface passing through a center position of the light source is a critical angle.   In the cross section, an incident angle of a light beam that is directly incident on a position on the exit surface from the light source is a predetermined angle from the maximum refraction angle as the radiation position on the light source approaches the bottom surface direction from the center position of the light source. 4. Illumination structure according to claim 3, wherein the illumination structure changes to a range of refraction angles.   The illumination structure according to claim 4, wherein a light beam emitted from a position on the light source in a direction away from the bottom surface from the center position of the light source and directly incident on the position on the emission surface is totally reflected.   The illumination structure according to claim 1, wherein a refraction angle in the predetermined range is 45 degrees or more.   The illumination structure according to claim 2, wherein in the cross section, the curve forming the emission surface is formed by a cubic curve or an arc having a predetermined radius and a central angle. The illumination structure according to claim 2, wherein the light beam traveling on the optical axis of the light source is incident on a position that protrudes most from the surface of the edge frame in the curve. The illumination structure of claim 1 plane tangent position protruding most outwardly from the surface of the edge frame is parallel to the surface of the edge frame. 2. The optical axis of the light source is inclined with respect to a normal to the surface of the edge frame so that a light beam that is directly incident on the emission surface from the light source and exits is directed toward the keyboard. Lighting structure.   The illumination structure according to claim 1, wherein the reflection surface causes the light directly incident from the light source to be totally reflected once and incident on the emission surface.

Images