AN ELECTRIC DEVICE WITH AN OPERATION INDICATING LAMP

Abstract: An electric device with an operation indicating light has a base and a case transversely divisible in a main frame and a case cover. The main frame is fitted to the base at one open end of the frame. A resin material is injected into the space provided by the base and the main frame. The case cover is fitted to the other open end of the main frame so that an operating indicating lamp can be seen through an indicating hole in the case cover. Thus, the device can be easily assembled, and the resin material does not leak from the gap between the operation indicating lamp and the indicating hole. Cracks are prevented from developing in the solder connecting the lamp to the circuit board. In addition, the lamp can be positioned at a high precision because no packing is required to prevent resin leakage.

Description: 1. Field of the Invention This invention relates to an electric device with an operation indicating lamp which may be used with a solid state relay and, more particularly to an improved device which can be easily assembled. 2. Related Art An electric device which is used for a solid state relay and has a light emitting diode (LED) as an operation indicating lamp is well known. In the conventional device, the LED is electrically connected to a circuit board and can be seen through an indicating hole disposed in the front cover of a case. A packing is interposed between the base of the LED and the front cover. The case is filled with a resin material which is injected through an opening in the case. The resin in set to fix the position of the circuit board and the electric components mounted on the board. However, before setting, the resin leaks out through the indicating hole and the gap between the front cover and the LED. Therefore, in order to prevent resin leakage, the base of the LED and the packing are continuously pushed against the cover until the resin is completely set. However, cracks easily develop in the solder electrically connecting the leads of the LED to the circuit board. The assembly of the device requires a long time. Further, because the packing for preventing resin leakage is easily deformed, the LED cannot be positioned exactly. SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide an electric device with an operation indicating lamp which prevents resin leakage. It is another object of this invention to provide an electric device with an operation indicating lamp which prevents cracks from developing in the solder electrically connecting the terminals of the LED to the circuit board. It is a still another object of this invention to provide an electric device with an operation indicating lamp which is easily assembled. It is a further object of this invention to provide an electric device with an operation indicating lamp which requires no packing to prevent resin leakage. It is a still further object of this invention to provide an electric device with an operation indicating lamp which is precisely positioned. According to this invention, there is provided an electric device with an operation indicating lamp comprising a base; a case transversely divisible into a main frame and a case cover, the main frame being fitted to the base and the case cover having an indicating hole; an operation indicating lamp visible through the indicating hole provided in the case cover; and a resin material for fixing the components in the case, the resin material being injected into the space provided by the base and the main frame. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front sectional view of an electric device with an operation indicating lamp and illustrating a first embodiment of the invention; Fig. 2 is a side sectional view of the device of Fig. 1; Fig. 3 is a disassembled perspective view of a case employed in an electric device with an operation indicating lamp in a second embodiment of the invention; Fig. 4 is a partial side sectional assembled view of the case of Fig. 3; Fig. 5 is a front sectional view of the device of Fig. 4; Fig. 6 is an enlarged partial-sectional view of Fig. 4; Fig. 7 is a disassembled perspective view of a case employed in an electric device with an operation indicating lamp in a third embodiment of the invention; Fig. 8 is a side partial-sectional view of the assembled case of Fig. 7; Fig. 9 is a sectional view of the case cover of Fig. 8; Fig. 10 is a disassembled perspective view of a case employed in an electric device with an operation indicating lamp in a fourth embodiment of the invention; Fig. 11 is a sectional view of the case cover of Fig. 10; Fig. 12 is an enlarged sectional view of the case cover of Fig. 11; Fig. 13 is a disassembled perspective view of a case employed in an electric device with an operation indicating lamp in a fifth embodiment of this invention; and Fig. 14 is a sectional view of the case cover of Fig. 13. DETAILED DESCRIPTION OF THE EMBODIMENTS Referring to Figs. 1 and 2, there is shown an electric device which may be employed in a resin molding type solid state relay. The device includes a case 2 which is divisible into a main frame 3 and a case cover 4. The case 2 is fitted to a base 1 at an open end of the main frame 3. A circuit board 5 is electrically connected to a plurality of terminals 6 which protrude from the base 1. An LED 7 serving as an operation indicating lamp is electrically connected to the circuit board 5 and visible through an indicating hole 2a of the case cover 4. A resin material 8 is injected into the space provided by the base 1 and the main frame 3 and set to fix the circuit board 5 and the components mounted on the board 5. The assembling method of the device will be described hereinafter. First of all, the LED 7 is positioned on the board 5 so that the top thereof slightly protrudes from an edge of the board 5 and is electrically connected to the board 5. Then, the board 5 is vertically set and electrically connected to the terminals 6. Subsequently, the main frame 3 is fitted to the base 1 at one open end of the frame 3. The resin material 8 is injected into the space provided by the base 1 and the main frame 3. Finally, the case cover 4 is fitted to the other open end of the main frame 3 so that the LED 7 can be seen through the indicating hole of the case cover 4. Because the indicating hole 2a is provided in the case cover 4, the resin material 8 does not leak from the indicating hole 2a and the gap between the LED 7 and the indicating hole 2a. The LED 7 does not need to be continuously pushed against the case cover 4, preventing cracks from developing in the solder connecting the LED 7 to the circuit board 5 and allowing the easy assembly of the device. Further, because no packings are required for preventing the resin leakage, the LED 7 can be positioned precisely. In Figs. 3 through 6 showing an electric device in accordance with a second embodiment of this invention, guide grooves 4c, 4c on case cover 4 are respectively engaged with guide rails 3c, 3c which are longitudinally provided along the longer edge of the open end of the main frame 3. The case cover 4 is slid along the guide rails 3c, 3c to plug the open end of the main frame 3. The case cover 4 has a protrusion 4b with which the cover 4 is locked to the open end of the main frame 3 (See Fig. 5). Further, as shown in Fig. 6, the indicating hole 2a is tapered with the inner diameter smaller than the outer one. Because the minimum diameter of the hole 2a is smaller than the diameter of the LED 7, a gap is not developed between the hole 2a and the LED 7 even if the LED is positioned with a deviation from the normal position, preventing foreign matter such as dust from entering. In the third embodiment, as shown in Figs. 7 through 9, the guides 4d, 4d of the case cover 4 are respectively engaged with the guide grooves 3d, 3d provided at the open end of the main frame 3. The case cover 4 is slid along the guide grooves 3d, 3d to plug the opening end of the main frame 3. In the fourth embodiment, as shown in Figs. 10 through 12, the case cover 4 has four locking holes 4e, and the main frame 3 has four locking pieces 3e at the open end. The cover 4 is mounted to plug the open end of the main frame 3 by locking the pieces 3e to the holes 4e. As shown in Fig. 12, the indicating hole 2a provided on the cover 4 is tapered with the outer diameter smaller than the inner one. Because the minimum diameter is smaller than the diameter of the LED 7, the LED 7 is positioned by the inner wall of the hole 2a leaving no gap between the LED 7 and the hole 2a. In this embodiment, because the case cover 4 is mounted on the main frame 3 before the resin is set, a bar 4g disposed on the cover 4 is fixed by the resin, preventing the cover 4 from coming off the main frame 3. In the fifth embodiment, as shown in Figs. 13 and 14, the cover 4 has four locking pieces 4f, and the main frame 3 has four locking holes 3f at the opening. The cover 4 is mounted to plug the open end of the main frame 3 by locking the pieces 4f to the holes 3f. It should be understood that the above description is merely illustrative of this invention and that many changes and modifications may be made by those skilled in the art without departing from the scope of the appended claims.

Claims: An electric device with an operation indicating lamp comprising: a base; a cage member transversely divisible into a main frame and a case cover, said main frame being fitted to said base, and said case cover having an indicating hole therein; an operation indicating lamp visible through said indicating hole; and a resin material for fixing the components in said case member, said resin material being injected into the space provided by said base and said main frame. An electric device with an operation indicating lamp according to Claim 1 wherein said main frame has at least one guide roll longitudinally provided along a longer of a pair of edges of an open end of said main frame, and said case cover has a guide groove engaging said at least one guide rail. An electric device with an operation indicating lamp according to Claim 2, including a pair of guide rails and guide grooves. An electric device with an operation indicating lamp according to Claim 1 wherein said main frame has at least one guide groove provided at an open end of said main frame, and said case cover has a guide engaging with said guide groove. An electric device with an operation indicating lamp according to Claim 4, including two pair of engaging guide grooves. An electric device with an operation indicating lamp according to Claim 1 wherein said case cover has a locking hole, and said main frame has a locking piece at its open end which is locked to said locking hole. An electric device with an operation indicating lamp according to Claim 6, including a plurality of locking pieces and locking holes. An electric device with an operation indicating lamp according to Claim 1 wherein said main frame has a locking hole at an open end, and said case cover has a locking piece which is locked to said locking hole. An electric device with an operation indicating lamp according to Claim 8, including a plurality of locking pieces and locking holes. An electric device with an operation indicating lamp according to Claim 1 wherein said indicating hole has a tapered opening. An electric device with an operation indicating lamp according to Claim 10 wherein said tapered opening is tapered toward said indicating lamp. An electric device with an operation indicating lamp according to Claim 10 wherein said tapered opening is tapered away from said indicating lamp. An electric device with an operation indicating lamp according to Claim 1 wherein said indicating light is an LED positioned on a circuit board adjacent said case cover. A method of making a resin filled electric device with an indicating light therein, comprising: a) positioning an indicating lamp on a circuit board, b) providing a base, a main frame and a separable cover, said cover having an indicating hole formed therein, c) connecting the board to electrical terminals in the base, d) assembling the main frame to the base, e) injecting resin in space formed by the main frame and base, and f) fitting the cover onto the main frame with the indicating light adjacent an inner edge of the hole in the cover. The method of Claim 14, including sliding the cover onto grooves on the main frame. The method of Claim 14, including interconnecting cooperating locking pieces and locking holes on the cover and the main frame.

Inventors: YAMAMOTO, MASATO OMRON TATEISI ELECTRONICS CO.
Applicants: OMRON TATEISI ELECTRONICS CO.
Application year: 1987
Main classification: H05K7
IPC codes: H05K5, H05K3, H01L23, H01L33