JP2007188681A - Surface light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface light-emitting device capable of improving utilization efficiency of a light source. <P>SOLUTION: On the surface light-emitting device, provided with a light guide body 20 having a light incident part 23 formed so as to protrude from the outer circumference of a ring-shaped part 22, and a light source 21 emitting light toward the incident part 23, a groove part 30 which converges in V-shape with its circumference direction as a maximum width is formed on the inner circumferential face of the annular part 22, and the light source 21 is arranged on the extension line of a straight line connecting the valley portion 30a of this groove part 30 and the center of the annular part 22. Thereby, the light which is emitted from the light source 21 and advances in the central direction of the ring-shaped part 22 is reflected by the slanted face 30b of the groove part 30 and advances to the inside of the ring-shaped part 22. As a result, leakage of light transmitting through the inner circumferential face of the annular part 22 and travelling toward central direction is eliminated and utilization efficiency of the light source 21 can be improved to that extent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is arranged on the back side of a nameplate or the like of a rotary operation type electrical component in which an illumination area is provided along a circumferential direction, and guides light from a light source to illuminate the illumination area in a ring shape. The present invention relates to a surface light emitting device.

  In a rotary operation type electrical component applied to an in-vehicle air conditioner system, an audio system, etc., in order to make the rotary operation position of a rotary knob rotated by a passenger visible in a dark place, An annular thin plate-shaped nameplate provided with a display portion is disposed around the rotary knob, and an annular light guide is disposed on the back side of the nameplate, and light from a light source such as a lamp is placed on the annular light guide. A surface light emitting device adapted to irradiate the display portion of the nameplate through a wide range is widely adopted (see, for example, Patent Document 1).

  FIGS. 7 to 9 illustrate a conventional surface light emitting device disclosed in Patent Document 1, FIG. 7 is a sectional view of a rotary operation type electric component to which the surface light emitting device is applied, and FIG. FIG. 9 is a perspective view of a light guide provided in the surface light emitting device. The rotary operation type electric component 1 shown in these drawings includes a rotary knob 2 that is rotated by a passenger, and a rotary encoder that is rotationally driven in conjunction with the rotary knob 2 (only the rotary shaft 6 is shown). An annular thin plate-shaped name plate 3 disposed around the rotary knob 2, a holder 4 that adheres and fixes the inner peripheral portion and the outer peripheral portion of the rear surface of the name plate 3, and an annular guide held by the holder 4 A light body 5, a light source 7 such as a lamp disposed adjacent to the light incident portion 5 c of the annular light guide 5, and a circuit board 8 on which the rotary encoder, the light source 7, and the like are mounted are provided. . The nameplate 3 is provided with a display portion 3a serving as an illumination region along the circumferential direction, and the annular light guide 5 faces the back surface of the display portion 3a of the nameplate 3.

  The annular light guide 5 is a molded product made of a material having high light transmission properties such as acrylic resin, and connects the small-diameter inner ring portion 5a and the large-diameter outer ring portion 5b, which are annular portions, at appropriate locations, The light incident portion 5c is formed in a shape protruding from the outer peripheral surface of the outer ring portion 5b on the extension line of the connecting portion. The light incident portion 5c is formed in a triangular shape in plan view with the outer peripheral surface of the outer ring portion 5b as the bottom, and the light source 7 is disposed so as to face a recess cut out in the bottom surface of the top portion of the light incident portion 5c (see FIG. 7). The annular light guide 5 guides the light of the light source 7 incident on the light incident part 5c to the inside of each ring part 5a, 5b and emits it upward, and the illumination emitted from the upper surface of the inner ring part 5a. The position mark 2a of the rotary knob 2 is illuminated with light, and the display portion 3a of the nameplate 3 is illuminated with illumination light emitted from the upper surface of the outer ring portion 5b. It is also known that the inner ring portion 5a is omitted and only the outer ring portion 5b is formed as an annular portion, and a light incident portion 5c having a triangular shape in plan view is formed on the outer peripheral surface of the annular portion (for example, Patent Document 2).

  The rotary knob 2 has only an illumination area where the position mark 2a exists, and the rotary knob 2 is provided with a flange portion 2b for preventing light leakage during illumination. The nameplate 3 is obtained by applying a light-shielding paint to the front surface of a light-transmitting resin plate except for the display portion 3a, and attaching a colored toning sheet to the entire back surface of the resin plate. The display unit 3a is illuminated by the body 5 with a desired color corresponding to the toning sheet. The display unit 3a is an illumination area in which symbols, characters, and the like, which are indicators of the rotational position of the rotary knob 2, are displayed along the circumferential direction, and it is visually observed where the position mark 2a indicates the display unit 3a. By doing so, the passenger can visually recognize the rotational operation position of the rotary knob 2. The holder 4 is a resin molded product, which also serves as an upper case that is integrated with a lower case (not shown), and the upper end surfaces of the small-diameter annular portion 4a and the large-diameter annular portion 4b adhere and fix the nameplate 3. ing. The circuit board 8 is attached to the lower case, and the rotary operation type electric component 1 is electrically connected to an external circuit through a connector portion (not shown) provided on the circuit board 8 and the lower case. It has become.

The rotary operation type electrical component 1 configured as described above is assembled in a state where the display portion 3a of the nameplate 3 and the rotary knob 2 are exposed in a circular opening 11 formed in the front panel 10 in the vehicle interior, The rotary knob 2 is set to protrude forward from the opening 11. When the occupant rotates the rotary knob 2, the rotation operation position can be confirmed by observing the relative position between the position mark 2a and the display unit 3a, and the position mark 2a Since the display unit 3a can be easily viewed with illumination light from the back side, the passenger can rotate the rotary knob 2 without any trouble.
Japanese Patent Laying-Open No. 2004-227855 (page 2-3, FIG. 6) JP 2004-288585 A (page 3-4, FIG. 1)

  By the way, in the surface emitting device described in Patent Document 1 among the above-described conventional techniques, a light incident part 5c is formed to protrude from the outer peripheral surface of the outer ring part 5b of the annular light guide 5, and the light incident part 5c is also formed. By arranging the light source 7 so as to face the triangular top, the light from the light source 7 is incident on the top of the light incident portion 5c and guided to the inside of the ring portions 5a and 5b continuous on the bottom side. The light traveling from the light source 7 toward the centers of the ring portions 5a and 5b is transmitted through the inner peripheral surface of the inner ring portion 5a. Similarly, in the surface light emitting device described in Patent Document 2, a light source is disposed opposite to the top of the light incident portion formed to protrude from the outer peripheral surface of the annular portion, and the light of this light source is incident on the top of the light incident portion. Since the light is guided to the inside of the annular portion, the light from the light source toward the center of the annular portion is transmitted through the inner peripheral surface of the annular portion. Accordingly, in any case, light leaks through the inner peripheral surface of the annular portion (inner ring portion 5a), and light from the light source that can be used as illumination light in the illumination region is reduced, resulting in insufficient brightness in the illumination region. There was a problem of causing an increase in power consumption of the light source.

  The present invention has been made in view of the situation of the prior art as described above, and an object thereof is to provide a surface light emitting device capable of increasing the utilization efficiency of a light source.

  In order to achieve the above object, the present invention provides a light guide having an annular part and a light incident part protruding from an outer peripheral surface of the annular part, and a light source that emits light toward the light incident part. In the surface light emitting device in which one of both opposing end faces of the annular portion is a light emitting surface and the other is a reflecting surface, the inner circumferential surface of the annular portion is V-shaped outward with the circumferential direction as both ends. The light source is arranged on a linear extension line connecting the apex of the groove and the center of the annular portion.

  In the surface light emitting device configured in this way, the light emitted from the light source and directed toward the center of the annular portion is reflected by the inclined surface of the groove portion and travels toward the inside of the annular portion, and thus transmits through the inner peripheral surface of the annular portion. There is no light leakage toward the central direction, and the use efficiency of the light source can be increased accordingly.

  In the above configuration, the end surface of the groove portion facing the light exit surface side of the annular portion is closed, and if an inclined surface inclined toward the light exit surface is formed in the closed portion, light traveling from the light source toward the center of the annular portion Part of the light is guided to the closed end of the groove by the inclined surface, so the local brightness decrease of the light emitting surface, which is a concern due to the presence of the groove, does not occur, and the light emitting surface including the part where the groove is formed is all around. It is preferable that it can be illuminated with a uniform light amount.

  In the above configuration, the light source may be opposed to the top of the light incident portion formed in a triangular shape in plan view. However, if the light source is disposed inside the cavity formed in the approximate center of the light incident portion, It is preferable that the light guide can be reduced in the radial direction while suppressing the protruding amount of the light portion.

  In the surface light emitting device of the present invention, a groove portion that converges outwardly in a V shape is formed on the inner peripheral surface of the annular portion, with the circumferential direction as both ends, and on a straight extension line connecting the apex of the groove portion and the center of the annular portion. A light source is disposed, and light emitted from the light source and traveling toward the center of the annular portion is reflected by the inclined surface of the groove portion and travels toward the inside of the annular portion. Therefore, the light passes through the inner peripheral surface of the annular portion and travels toward the center. There is no light leakage, and the use efficiency of the light source can be increased accordingly.

  An embodiment of the invention will be described with reference to the drawings. FIG. 1 is a perspective view of a light guide provided in a surface light emitting device according to an embodiment of the present invention, and FIG. 2 is a view of the light guide from the back side. FIG. 3 is a cross-sectional view showing the surface light emitting device in use, FIG. 4 is a transverse cross-sectional view of the light incident portion of the light guide, and FIG. 5 is a vertical cross-sectional view of the light incident portion of the light guide. FIG. 6 is an explanatory diagram showing in plan the path of light emitted from the light source.

  The surface light-emitting device according to the present embodiment includes a light guide 20 that is a molded article made of a material having high light transmittance such as acrylic resin, and a light source 21 that enters the light into the light guide 20. The lamp is used as the light source 21. The light guide 20 includes an annular portion 22 that bends light, and a light incident portion 23 that is integrally formed on the outer peripheral surface of the annular portion 22 and protrudes outward. The annular portion 22 is a light incident portion 23. The plate thickness is reduced as the distance from is increased. The upper side of the annular portion 22 is a flat light exit surface 22a, and the lower side of the annular portion 22 is a sawtooth reflecting surface 22b. As shown in FIG. 2, the sawtooth reflecting surface 22b is composed of a large number of sawtooth projections extending in the radial direction along the circumferential direction, and the light that is bent inside the annular portion 22 is sawtooth reflected. The light is reflected by the surface 22b and emitted from the light exit surface 22a. A cavity 24 is provided in the center of the light incident portion 23, and the light source 21 mounted on the circuit board 25 is arranged at the center position in the cavity 24 as shown in FIG. 3. .

  The light incident portion 23 of the light guide 20 will be described in detail. The cavity 24 is a through-hole penetrating the light incident portion 23 in the plate thickness direction, and the zenith direction of the light source 21 disposed in the cavity 24 is an open end. ing. A pair of slits 24a extending from the opening end to the middle of the plate thickness direction is formed on the inner wall surface of the light incident portion 23 that defines the cavity 24, and the side where the annular portion 22 exists with these slits 24a as a boundary. The region on the opposite side is the retroreflective portion 26. On the outer wall surface of the retroreflective portion 26, a plurality of outward projecting ridge portions 26a extending along the plate thickness direction are formed, and among the light emitted from the light source 21 in four directions, the light emitted backward. Is reflected by the outward projecting ridge 26 a and is directed to the annular portion 22. The retroreflective portion 26 may be continuous with the inner wall surface of the light incident portion 23 without forming the slit 24a.

  On the other hand, the outer condensing lens portion 27 and the inner condensing lens portion 28 are formed at two locations on the left and right sides of the inner wall surface of the light incident portion 23 in the region where the annular portion 22 exists with the slit 24a as a boundary. ing. As shown in FIG. 4, when the straight line connecting the center of the light source 21 and the annular portion 22 arranged in the cavity 24 is P, the outer condenser lens part 27 and the inner condenser lens part 28 on both the left and right sides are related to the straight line P. They are formed at symmetrical positions, both of which are continuous in the order of the outer condensing lens portion 27 and the inner condensing lens portion 28 from the slit 24 a toward the inside of the cavity 24. In addition, the left and right outer wall surfaces of the light incident portion 23 are formed with reflection portions 29 that bulge outwardly, and these reflection portions 29 are formed from the first reflection surface 29 a closer to the light source 21 and the light source 21. The distant second reflection surface 29b is continuous with an obtuse angle close to 180 degrees. The left and right reflecting portions 29 are also formed at symmetrical positions with respect to the straight line P. In both cases, the first reflecting surface 29a extends from the slit 24a along the outer wall surface of the light incident portion 23, and is formed on the second reflecting surface 29b. The second reflection surface 29b is continuous with the end portion, and is continuous with the outer peripheral surface of the annular portion 22 from the end portion of the first reflection surface 29a. Here, the outer condensing lens unit 27 described above is located between the light source 21 and the first reflecting surface 29a. When the light from the light source 21 enters the outer condensing lens unit 27, the outer condensing lens unit 27 is refracted. The shape of the lens portion 27 is designed so as to be directed to the first reflecting surface 29a. Further, the inner condensing lens portion 28 is located between the light source 21 and the annular portion 22, and refracts when the light from the light source 21 enters the inner condensing lens portion 28 and travels toward the inside of the annular portion 22. Thus, the shape of the lens portion 28 is designed.

  As shown in FIG. 2, a groove portion 30 that converges in a V shape with the circumferential direction as a maximum width is formed on the inner peripheral surface of the annular portion 22, and the trough portion 30 a that is the apex of the groove portion 30 is described above. It is formed at a position substantially coinciding with the straight line P (see FIG. 4). That is, the center of the annular portion 22, the valley portion 30 a of the groove portion 30, and the light source 21 are set so as to be positioned on the same straight line P, and both slopes 30 b and 30 b of the groove portion 30 that are diagonally opposed across the straight line P. Is inclined so as to spread outward toward the inner peripheral surface of the annular portion 22. The groove portion 30 maintains a V-shaped cross-sectional shape and extends in the plate thickness direction of the annular portion 22, but the end portion of the groove portion 30 on the light output surface 22 a side is closed, and this closed portion has an inclined surface. 30c is formed. The inclined surface 30c is inclined from the valley portion 30a of the groove portion 30 toward the light exit surface 22a, and the light emitted from the light source 21 toward the upper end blocking portion of the groove portion 30 is inclined as shown by the arrow in FIG. The light is reflected by 30c and emitted from the light exit surface 22a. On the other hand, the end portion of the groove portion 30 on the sawtooth reflection surface 22b side is open, and a pair of inclined surfaces 22c facing each other with the groove portion 30 in between are formed on the lower surface of the annular portion 22. These inclined surfaces 22c are also inclined toward the light exit surface 22a, and the light emitted from the light source 21 and directed to both sides of the lower end of the groove portion 30 is reflected by the inclined surface 22c and emitted from the light exit surface 22a. Thus, among the light emitted from the light source 21 in all directions, part of the light emitted toward the front side and directed toward the groove 30 is guided to the light exit surface 22a by the inclined surface 30c and the inclined surface 22c. The local luminance decrease of the light exit surface 22a which is a concern due to the presence of 30 does not occur, and the light exit surface 22a can be illuminated with a uniform amount of light over the entire circumference.

  In FIG. 6, of the light emitted from the light source 21, the path of light incident in the counterclockwise direction (counterclockwise direction) on the curved optical path of the annular portion 22 is indicated by an arrow. As shown in the figure, the light incident on the outer condenser lens portion 27 from the light source 21 is refracted by the lens portion 27 and travels toward the first reflecting surface 29a, and then is reflected by the first reflecting surface 29a. Then, it proceeds toward the inside of the annular portion 22. The light incident on the inner condensing lens portion 28 from the light source 21 is refracted by the lens portion 28 and travels in the direction of the annular portion 22, and then a part of the light is reflected by the second reflecting surface 29 b. Proceed toward the inside of the annular portion 22. That is, the light incident from the light source 21 to the inner wall surface of the light incident part 23 (the outer condenser lens part 27 and the inner condenser lens part 28) does not pass through the outer wall surface of the light incident part 23 as it is. Light leakage on the outer wall surface 23 is prevented by the reflecting portion 29 (first and second reflecting surfaces 29a and 29b). Further, light incident from the light source 21 in front of the cavity 24 (in the center direction of the annular portion 22) is reflected by the inclined surface 30 b of the groove portion 30 and travels toward the inside of the annular portion 22. The light emitted from the light source 21 to the rear side of the cavity 24 is reflected by the outward protrusion 26a formed on the outer wall surface of the retroreflective portion 26 and becomes recursive light toward the annular portion 22, and this recursive light. Is also incident on the outer condenser lens part 27 and the inner condenser lens part 28 and takes the same path as described above.

  The light emitted from the light source 21 thus guided into the annular portion 22 is bent counterclockwise while repeating reflection on the inner wall surface of the annular portion 22, and a part of the light is reflected by the sawtooth reflecting surface 22b. Then, the light exits from the light exit surface 22a. At that time, since the annular portion 22 is formed so that the plate thickness becomes thinner as it is away from the light incident portion 23, the luminance of the illumination light emitted from the light exit surface 22a of the annular portion 22 is set almost uniformly over the entire circumference. It becomes possible. Moreover, as described above, a part of the light emitted forward of the light source 21 is emitted from the light exit surface 22a directly above the groove portion 30 by the inclined surface 30c, and the light exit surface near the upper portion of the groove portion 30 by the inclined surface 22c. Since the light is emitted from 22a, the local luminance reduction of the light exit surface 22a which is a concern due to the presence of the groove portion 30 does not occur, and the light exit surface 22a can be illuminated with a uniform light amount over the entire circumference. Although not shown in the drawing, the path of light incident in the clockwise direction (clockwise direction) on the curved optical path of the annular portion 22 is the same.

  In the surface light emitting device configured as described above, for example, the annular portion 22 of the light guide 20 is disposed on the back side of a nameplate (not shown) of the rotary operation type electrical component, and the light source 21 on the circuit board 25 is placed in the cavity 24. Therefore, the display portion, which is the illumination region of the nameplate, can be illuminated by the illumination light emitted from the light exit surface 22a of the annular portion 22. As explained in the conventional example, this nameplate is arranged around a rotary knob (not shown), and the relative position between the display portion provided along the circumferential direction of the nameplate and the position mark provided on the rotary knob. By looking at, the rotation operation position of the rotary knob can be visually recognized. Further, a rotating shaft (not shown) to which the rotating knob is attached is loosely inserted into the annular portion 22 of the light guide 20, and the rotating shaft is rotated through the rotating knob, whereby the rotation on the circuit board 25. A rotary encoder (not shown) is driven to rotate.

  As described above, in the surface light emitting device according to this embodiment, the groove portion 30 that converges in a V shape with the circumferential direction as the maximum width is formed on the inner peripheral surface of the annular portion 22. Since the light source 21 is arranged on the extended line of the straight line P connecting the center of the annular portion 22 with the portion 30a), the light emitted from the light source 21 toward the center of the annular portion 22 is reflected by the inclined surface 30b of the groove portion 30. Therefore, it goes to the inside of the annular portion 22. As a result, there is no light leaking through the inner peripheral surface of the annular portion 22 toward the central direction, and the utilization efficiency of the light source 21 can be increased accordingly.

  Further, the end portion of the groove portion 30 on the light exit surface 22a side is closed, and an inclined surface 30c that is inclined toward the light exit surface 22a is formed in the closed portion, so that light traveling from the light source 21 toward the center of the annular portion 22 is formed. Is reflected by the inclined surface 30c formed right above the groove 30 and guided to the light exit surface 22a side. As a result, the local brightness decrease of the light exit surface 22a, which is a concern due to the presence of the groove portion 30, is suppressed, and the light exit surface 22a including the formation portion of the groove portion 30 can be illuminated with a uniform light amount over the entire circumference. . Moreover, a pair of inclined surfaces 22c facing each other with the groove 30 interposed therebetween are formed on the sawtooth reflection surface 22b side of the annular portion 22, and these inclined surfaces 22c are also inclined toward the light exit surface 22a. A part of the light traveling from 21 toward the center of the annular portion 22 is reflected by the inclined surface 22c and guided to the light exit surface 22a on the side of the groove 30. Therefore, in combination with the above-described illumination operation directly above the groove portion 30 by the inclined surface 30c, a local decrease in luminance of the light emission surface 22a at the portion corresponding to the groove portion 30 is effectively suppressed, and the light emission surface 22a is completely removed. It can be illuminated with a uniform amount of light over the circumference.

  Further, a cavity 24 is formed in the center of the light incident portion 23 protruding from the outer peripheral surface of the annular portion 22, and light is incident from the light source 21 disposed in the cavity 24 toward the inner wall surface of the light incident portion 23. As a result, the entire light guide 20 can be reduced in size in the radial direction by suppressing the amount of protrusion of the light incident portion 23 from the annular portion 22, and the light incident on the inner wall surface of the light incident portion 23 from the light source 21 can be reduced. Most of the light can be used as illumination light, and the utilization efficiency of the light source 21 can be increased from this point.

It is a perspective view of the light guide with which the surface emitting device concerning the example of an embodiment of the present invention is equipped. It is the perspective view which looked at this light guide from the back side. It is sectional drawing which shows the use condition of this surface emitting device. It is a cross-sectional view of the light entrance part of the light guide. It is a longitudinal cross-sectional view of the light-incidence part of this light guide. It is explanatory drawing which shows the path | route of the light radiate | emitted from the light source planarly. It is sectional drawing of the rotation operation type electric component to which the conventional surface emitting device was applied. It is a top view of this rotation operation type electric component. It is a perspective view of the light guide with which this surface emitting device is equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Light guide 21 Light source 22 Annular part 22a Light emission surface 22b Sawtooth-like reflective surface 22c Inclined surface 23 Light incident part 24 Cavity 25 Circuit board 30 Groove part 30a Valley part 30b Slope 30c Inclined surface P Straight line

Claims (3)

A light guide having an annular portion and a light incident portion projectingly formed on the outer peripheral surface of the annular portion; and a light source that emits light toward the light incident portion; A surface emitting device in which one is a light emitting surface and the other is a reflecting surface,
A groove portion that converges outwardly in a V shape is formed on the inner circumferential surface of the annular portion, and the light source is disposed on a straight line extending between the apex of the groove portion and the center of the annular portion. A surface light emitting device characterized by the above.   2. The surface light emitting device according to claim 1, wherein an end surface of the groove portion on the light exit surface side is closed, and an inclined surface inclined toward the light exit surface is formed in the closed portion.   3. The surface light emitting device according to claim 1, wherein a cavity is formed at substantially the center of the light incident portion, and the light source is disposed inside the cavity.

Images