Structure of a diffusing lens for a light emitting diode

Abstract: A structure of a diffusing lens for a light emitting diode (LED). The diffusing lens is mounted on, for example, part of the casing of a receiver included in a telephone. A relatively thick plate-like diffusing lens is press fitted in a slot formed in an end portion of the receiver. Implemented by a light transmitting member, the lens transmits light issuing from an LED in a direction perpendicular to the thicknesswise direction thereof while diffusing it in a predetermined direction. Two holes are formed through the lens in the thicknesswise direction, and each receives and retains an LED therein. Two leads extending out from each LED are drawn out from both ends of the associated hole of the lens and connected to a flexible printed circuit board.

Description: The present invention relates to a lens for diffusing, in predetermined directions, light which issues from a light emitting diode (LED) and, more particularly, to the structure of such a lens which is built in part of the casing of electronic equipment having only a limited space therein. A portable or cordless telephone which is known to the applicants has a casing formed with a slot, and a diffusing lens received in the slot. When a call arrives at the telephone, an LED accommodated in the casing emits light while the lens diffuses the light to the outside of the casing to alert the user of the telephone to the call. The lens is implemented as a relatively thick plate-like light transmitting member and has the outer surface thereof so configured as to form part of the outer periphery of the casing. The LED is located in close proximity to the lens in the casing and supported by a support member in a predetermined position. The support member is affixed to the casing. Inside the casing, part of the lens is notched to form a recess for receiving the LED. As stated above, it is necessary with the previously proposed, but not published, structure to confine the printed circuit board and the support member affixed to the circuit board and support the LED in a predetermined position, i.e., in the recess of the lens in the limited narrow space of the casing. This prevents the various parts from being freely arranged in the casing. A feature of a structure to be described is that it enables a diffusing lens, a printed circuit board, and a light emitting diode to be freely arranged in a narrow space in an equipment casing. In a particular arrangement to be described below there is a diffusing lens which includes a relatively thick plate-like light-transmitting member for transmitting light in a direction perpendicular to the thickness of the member while diffusing the light in predetermined directions, the diffusing lens having at least one hole extending through the thickness of the member and a light emitting diode retained in the hole. The following description and drawings disclose a previously proposed arrangement and, by means of an example, the invention which is characterised in the appended claims, whose terms determine the extent of the protection conferred hereby. In the drawings:- FIG. 1 is a fragmentary perspective view of the casing of a telephone on which a diffusing lens having a conventional structure is mounted; FIG. 2 is a section showing the diffusing lens of FIG. 1 together with members adjoining it; FIG. 3 is a perspective view of a diffusing lens embodying the present invention and mounted on the casing of a telephone; FIG. 4 is a perspective view showing the lens of FIG. 3 specifically; and FIG. 5 is a section showing the lens of FIG. 3 fixed in place in the casing. To understand better the present invention, a brief reference will first be made to a previously proposed structure of a diffusing lens for an LED known to the applicants and shown in FIGS. 1 and 2. As shown, a diffusing lens 16 is mounted on part, i.e., the end of the casing 12 of a telephone 10 by way of example. Specifically, the casing 12 is formed with a slot 14 from the top 12a to the front 12b thereof. The lens 16 in the form of a relatively thick plate is press fitted in the slot 14. Implemented by a light transmitting member, the lens 16 transmits light in a direction perpendicular to the thicknesswise direction thereof while diffusing it in a predetermined direction. The lens 16 has an outer surface 16a which is flush with the outer periphery of the casing 12. A notch or recess 16b is formed in the inner periphery of the lens 16 which faces the interior of the casing 12. In the casing 12, an LED 18 is located in the vicinity of the lens 16 and supported by a support member 20 which is in turn affixed to a printed circuit board 22. The LED 18 is received in the recess 16b of the lens 16. As stated above, the printed circuit board 22 and the support member 20 supported by the circuit board 22 while positioning the lens 16 in the recess 16b have to be accommodated in the limited space of the casing 12. This brings about a drawback that the various parts cannot be freely arranged in the casing 12, as discussed earlier. Referring to FIG. 3-5, a diffusing lens for an LED embodying the present invention will be described which is mounted on part, i. e., the end of the receiver of a telephone by way of example. As shown, the receiver, has a slot 24 at the end of a casing 12 thereof. A diffusing lens 26 in the form of a relatively thick plate is press fitted in the slot 24. The lens 26, like the conventional lens, is implemented by a light transmitting member and transmits light while diffusing it in a predetermined direction. The lens 26 has an end face or emitting face 26a which is exposed to the outside and flush with the outer periphery of the casing 12. More specifically, when the lens 26 is received in the slot 24, the end face 26a forms part of the outer surface of the casing 12. For this purpose, as shown in FIG. 4, the lens 26 is made up of a relatively thick intermediate plate portion 26A having the end face 26a and opposite relative thick plate portions 26B sandwiching the intermediate portion 26A. Holes 28 and 30 are formed through the lens 26 in the thicknesswise direction for receiving LEDs 32 and 34, respectively. A flexible printed circuit board 36 is fixed in place in the casing 12. Leads 32a and 32b and leads 34a and 34b extend out respectively from the LEDs 32 and 34 which are received in the holes 28 and 30. The leads 32a and 32b are drawn out from both ends of the hole 28 and connected to the printed circuit board 36. Likewise, the leads 34a and 34b are drawn out from both ends of the hole 30 and connected to the printed circuit board 36. It is to be noted that the embodiment uses two LEDs 32 and 34 for simply eliminating the irregular distribution of light. As shown in FIG. 5, the printed circuit board 36 made of a flexible material is affixed to the casing 12 with the end portion 36a thereof facing the rear 26c of the lens 26 with the intermediary of a gap 22a. As stated above, in the illustrative embodiment, the LEDs 32 and 34 are retained by the diffusing lens 26 and not by the conventional support member 20, FIGS. 1 and 2. Therefore, it is not necessary to provide the casing 12 with a space otherwise occupied by the support member 20. In addition, since the printed circuit board 36 does not have to hold such a support member, it can be provided with a thinner, lighter and mechanically less strong configuration than the conventional one 12. Hence. it is possible to mount the lens 26 even on a miniature receiver. In summary, it will be seen that the present invention provides a diffusing lens which is formed with a hole for receiving and supporting an LED and, therefore, eliminates the need for an exclusive support member heretofore accommodated in an equipment casing for supporting the LED. This reduces the number of constituent parts and the required space and allows, among others, a printed circuit board to be freely arranged in the casing. Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope of the invention, as defined in the appended claims.

Claims: A diffusing lens (26) structure including a relatively thick plate-like light transmitting member (26A) for transmitting light in directions perpendicular to the thickness of the member (26A) and diffusing the light in a predetermined manner, characterised in that there is at least one hole (28) (30) through the thickness of the lens (26) and in that a light emitting diode (LED) (32) (34) is retained in the hole (28) (30) by the diffusing lens (26). A structure as claimed in claim 1, wherein the diffusing lens (26) is mounted on a part of the casing (12) of an equipment, part (26a) of the diffusing lens (26) being exposed at the outside of the casing (12) and forming a light emitting surface (26a) which constitutes a part of the surface of the casing (12). A structure as claimed in claim 2, wherein the diffusing lens (26) includes a relatively thick intermediate plate portion (26A) and two relatively thick plate portions (26B), each arranged on a respective opposite side of the intermediate plate portion (26A), the intermediate plate portion (26A) being sandwiched between them. A structure as claimed in claim 2, wherein a printed circuit board (36) is fixed to the casing (12) and is located to face the rear of the diffusing lens (26), and wherein leads (32a, 32b) (34a 34b) extend out from the light emitting diode (32) (34) which is retained in the hole (28) (30) through the lens (26) and are connected to the printed circuit board (36). A structure including a plate-like diffusing lens (26) for diffusing light emitted from a light emitting device (32) (34), and a slot (24) formed at an end of a casing (12) of an equipment, the lens (26) being fitted in the slot (24), characterised in that there is a hole (28) (30) through the thickness of the diffusing lens (26) and in that the light emitting device (32) (34) is retained in the hole (28) (30). A structure as claimed in claim 5, further including a printed circuit board (36) to which at least two connection leads (32a, 32b) (34a, 34b) of the light emitting device (32) (34) are electrically connected. A structure as claimed in claim 6, wherein the printed circuit board (36) is flexible. A structure as claimed in claim 5, wherein the light emitting device (32) (34) is a light emitting diode. A structure as claimed in claim 5, wherein the outer surface of (26a) the diffusing lens (26) is flush with the outer surface of the casing (12). A method of mounting a light emitting device (32) (34) in an equipment casing (12), including the steps of forming a slot (24) in a part of the casing (12), fitting a plate-like diffusing lens (26) in the slot (24), there being a hole (28) (30) through the thickness of the lens (26), and introducing the light emitting device (32) (34) into the hole (28) (30), the light emitting device (32) (34) being retained in the hole (28) (30) by the lens (26). A method as claimed in claim 10, further including the step of electrically connecting the leads (32a 32b) (34a 34b) of the device (32) (34) to a flexible printed circuit board (36).

Inventors: NAGAI MICHIO, NAGAI, MICHIO
Applicants: NIPPON ELECTRIC CO, NEC CORPORATION
Application year: 1992
Main classification: H05K5
IPC codes: H04M1, H05K5, G02B3, H01L33, G02B5