Illumination type electronic part of rotational operation

Abstract: The present invention relates to an illumination type electronic part of rotational operation which is used in audio equipment or the like and makes it possible to recognize the position of rotational operation of a knob by the light from a built-in light emitting device. Its object is to provide an illumination type electronic part of rotational operation which is able to cope with changes in specifications for the rotational operation shaft readily, to withstand a strong thrust force applied to the rotational operation shaft, to reduce the hitting sound emitted from the rotatable stopper of the rotational operation shaft, and also to light up the illumination means disposed on the end of the rotational operation shaft in a stable manner. In order to achieve the foregoing object, the rotational operation shaft is made in a simple hollowed cylindrical shape, and also the rotor having a flange and a stopper for restricting the extent of its rotational motion is prepared separately from the rotational operation shaft and produced by resin molding. Furthermore, the rotor is made of a transparent resin and integrally molded together with the light collecting lens for the light emitting device.

Description: BACKGROUND OF THE INVENTION The present invention relates to an illumination type electronic part of rotational operation, which is mainly used in audio equipment and capable of indicating clearly the operational positions of its knob by means of light from a built-in light source such as an LED (Light Emitting Diode). A motor-driven illumination type variable resistor of rotational operation will be explained as an example of the prior art illumination type electronic part of rotational operation with the help of Fig. 5 through Fig. 8. As shown in the drawings, the motor-driven illumination type variable resistor of rotational operation is composed of a variable resistor 1, a speed reduction gear mechanism 2, and a motor 3. The variable resistor 1 is composed of a metal bushing 5, a resistance varying means, and an illuminating means. The bushing 5 has a housing member 4. The resistance varying means is composed of a rotational operation shaft 11, which is supported by the bushing 5 and freely rotatable, a driver 12, a brush holder 13, a brush 14, and a resistor substrate 15. The rotational operation shaft 11 is integrally formed of a cylindrical member 7 which has a through-hole 6 therein, a flange 8 disposed on the rear end of said cylindrical member 7, a projection 9 disposed at a position of the periphery of said flange 8, and a bow-shaped linkage 10 disposed on the end of said projection 9. The brush holder 13 is linked with the bow-shaped linkage 10 by means of a projection for linkage 12A of the driver 12. The resistor substrate 15 is held by a substrate holder 19, and a resistor is formed on the surface of said substrate 15. The illuminating means is comprised of an LED 16, which serves as a light source and is located inside the concaved housing 4 and at the rear end of the feed-through hole 6 of the rotational operation shaft 11, and a holder 17 for holding the LED 16. Besides, the rotational motion of the rotational operation shaft 11 is restricted in its extent by the projection 9 of the rotational operation shaft 11 hitting a projection 18 disposed at the lower portion of the concaved portion of the housing 4 of the bushing 5. Also, a housing box 20 of the speed reduction gear mechanism 2 and the motor 3 are put together with the back of the substrate holder 19 of the variable resistor 1 and, at the same time, the bushing 5, the substrate holder 19 and the housing box 20 are put together to make an integral body by means of a U shaped bracket 21, to which the motor 3 is fastened by screws. This structure makes it possible to transmit the rotational motion of the motor 3 to the driver 12 of the variable resistor 1 through the speed reduction gear mechanism 2. Accordingly, when the motor 3 is rotated by application of a voltage, the rotational motion thereof is reduced in its speed by the speed reduction gear mechanism 2 and transmitted to the projection for linkage 12A of the driver 12 of the variable resistor 1. The brush holder 13 linked with said projection for linkage 12A is rotated and the brush 14 held by the brush holder 13 is moved in sliding on the resistor substrate 15 to change resistance values. At this time, a voltage is applied across terminals 22 and the LED 16 is activated to emit light. The emitted light reaches out of the rotational operation shaft 11 through the feed-through hole 6 and illuminates an indicator of a knob (not shown in the drawings) mounted on the end of the rotational operation shaft 11. Further, in connection with the transmission of rotational motion between a last stage reduction gear 23 of the speed-reduction gear mechanism 2 and the projection for linkage 12A of the driver 12, a structure, wherein the transmission is carried out by means of a friction clutch 25 using a sheet spring 24, is employed. In case where the variable resistor is manipulated by rotating the rotational operation shaft 11 by hand, said clutch 25 is forced to slip. However, with the foregoing prior art illumination type variable resistor of rotational operation, all of the long cylindrical member 7 having the feed-through hole 6, the flange 8 on the rear end of the cylinder, the projection 9 on the periphery of the cylinder, and the bow-shaped linkage 10 on the rear end of the cylinder have to be put together into an integral body to build the rotational operation shaft 11. Besides, such a molding method as metal die casting or the like requiring a complicated molding die has to be used in making said rotational operation shaft 11. Consequently, the aforementioned structure has presented an inherent difficulty in coping with changes in specifications for the length of the rotational operation shaft 11, the diameter of a knob mounting portion 11A of the rotational operation shaft 11, and the position of a flat portion 11B of the rotational operation shaft 11 to fix the position of a knob against its rotational direction. On account of the flange 8 which has a larger diameter than that of a fitting receptacle of the bushing 5 and is integrally molded with the rear end of the rotational operation shaft 11, the rotational operation shaft 11 has to be inserted from the back of the receptacle of the bushing 5 to put together the bushing 5 and the rotational operation shaft 11. Therefore, when a strong thrusting force is applied to the rotational operation shaft 11 from the front at the time of mounting a knob or the like onto the rotational operation shaft 11, there has been a danger of inflicting damages to some component parts such as the resistor substrate 15 or the like. A stopper mechanism to restrict the extent of the rotational motion of the rotational operation shaft 11 is built in such a way that the projection 9 of the metallic rotational operation shaft 11 made by a die-casting method or the like hits the projection 18 of the concaved housing 4 of the metallic bushing 5 made by a die-casting method or the like. Accordingly, a hitting sound is generated on account of striking between metals with a resultant annoying adverse effect imposed on electrical parts, especially on the ones intended for use in audio equipment. Besides, due to the long and slender feed-through hole 6 which serves as the light channel for the light emitting device of the LED 16, the light intensity will be reduced at the end of the feed-through hole 6, where an indicator of the knob to be illuminated is located, even when an LED of strong directivity is used. Also, it has been a problem that scattering in the values of illumination intensity tends to exist from product to product. SUMMARY OF THE INVENTION The present invention is to provide a solution to the afore-mentioned problems associated with the prior art and its object is to provide an illumination type electronic part of rotational operation which can readily cope with changes in specifications for a rotational operation shaft, can withstand a strong thrusting force applied to the rotational operation shaft, makes only a small hitting sound at the rotation stopper of the rotational operation shaft and also has such effects as stabilized lighting of the illuminating means disposed on the end of the rotational operation shaft or the like. In order to solve the foregoing problems, the illumination type electronic part of rotational operation of the present invention has a structure comprising: a driver interlinked with a brush holder; a substrate which is kept in contact with a brush mounted on said brush holder; a bushing with a concaved housing; a cylindrical rotational operation shaft which is fitted into and supported by said bushing so as to keep the shaft rotating freely and in possession of an elevated step portion for stopping a thrust motion of the rotational operation shaft hitting said bushing, and a feed-through hole; a resin-made rotor which is fixed to the rear end of said rotational operation shaft and in possession of a stopper means of restricting the extent of rotational motion of said rotational operation shaft, a means of linking with the driver, and a recess in its center; and a light emitting device disposed inside said concaved housing and in the back of said recess of the rotor. Simply said, the structure comprises a rotational operation shaft of a simple hollowed cylindrical shape, an elevated step portion for stopping a thrust force disposed on said rotational operation shaft, and a rotor, which has a stopper for restricting the extent of its rotational motion and is prepared separately from the rotational operation shaft by resin molding. The foregoing structure makes it possible to cope readily with changes in specifications for the rotational operation shaft and also to prevent damages from inflicting on the substrate when the rotational operation shaft is manipulated, and furthermore has such effects as prevention of abnormal sound generation or the like. Besides, by having the rotor molded by use of a transparent resin and also having the light collecting lens for the light emitting device molded together, it will be possible to make the illuminating means disposed on the end of the rotational operation shaft much brighter. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional side view of an illumination type electronic part of rotational operation as one of the exemplary embodiments of the present invention. Fig. 2 is a perspective view of an illumination type electronic part of rotational operation as one of the exemplary embodiments of the present invention. Fig. 3 is an exploded illustration of a variable resistor forming a principal portion of an illumination type electronic part of rotational operation as one of the exemplary embodiments of the present invention. Fig. 4 is an exploded illustration of a speed reduction gear mechanism forming a principal portion of an illumination type electronic part of rotational operation as one of the embodiments of the present invention. Fig. 5 is a sectional side view of a prior art illumination type electronic part of rotational operation. Fig. 6 is a perspective view of a prior art illumination type electronic part of rotational operation. Fig. 7 is an exploded perspective illustration of a variable resistor forming a principal portion of a prior art illumination type electronic part of rotational operation. Fig. 8 is an exploded perspective illustration of a speed reduction gear mechanism forming a principal portion of a prior art illumination type electronic part of rotational operation. Key to Symbol 31 Variable Resistor 32 Speed Reduction Gear Mechanism 33 Motor 34 Concaved Housing 35 Bushing 36 Elevated Step Portion 37 Feed-through Hole 38 Rotational Operation Shaft 39 Stopper 40 Driver 41 Fitting Hole 42 Recess 43 Light Collecting Convex Lens 44 Rotor 45 Arm 46 Brush Holder 47 Brush 48 Resistor Substrate 49 Light Emitting Device 50 Holder 51 Terminals 52 Projection 53 Substrate Holder 54 Housing Box 55 Frame 56 Speed Reduction Gear 57 Friction Spring 58 Friction Clutch DETAILED DESCRIPTION OF THE INVENTION Details of an illumination type electronic part of rotational operation of the present invention will be explained according to an exemplary embodiment. Fig. 1 through Fig. 4 show the structure of a motor-driven illumination type variable resistor of rotational operation as one of the exemplary embodiments of the present invention. As shown in Fig. 1 through Fig. 4, the motor-driven illumination type variable resistor of rotational operation is composed of a variable resistor 31, a speed reduction gear mechanism 32, and a motor 33. The variable resistor 31 is further made up of a bushing 35, a resistance varying means, and an illuminating means. The bushing 35 is composed of a concaved housing 34 disposed on its base, a bushing's end Portion 35B extending out to the front, and a circular hole 35A in its central portion, and also is molded by metal or resin. The resistance varying means is composed of a cylindrical rotational operation shaft 38, a rotor 44 made of resin, a driver 40 made by a metal die-casting method, a brush 47, and a resistor substrate 48. The rotational operation shaft 38 is comprised of an elevated step portion 36 disposed on its periphery to come into contact with the bushing's end portion 35B, a feed-through hole 37 slightly tapered off from a larger diameter hole 37A at the rear end to a smaller diameter hole 37B at the front end, and a flat portion 38A which can be changed in its position freely, and is fitted into and supported by said circular hole 35A of the bushing 35. The rotor 44 is comprised of a stopper 39 disposed on its periphery for restricting the extent of rotational motion of the rotational operation shaft 38, a fitting hole 41 disposed on its rear end to put the driver 40 in motion, a recess 42 disposed in its center, and a transparent convex lens 43 for light collection disposed in the front end of the recess 42 at a position which corresponds to a place a little recessed from the larger diameter portion 37A located in the rear end of the rotational operation shaft 38. The rotor 44 is prepared separately from the rotational operation shaft 38 and put together with the rotational operation shaft 38 by staking to its rear end. The rotor 44 can also be formed integrally with the lens 43 by employing a transparent molding resin. The driver 40 is comprised of an arm 45 which has a projection 45A disposed on its end and engaged with the fitting hole 41 of the rotor 44, and a center shaft 40A extending backward. The brush 47 is disposed on a brush holder 46 and inter-linked with the center shaft 40A of the driver 40 for rotating together with the center shaft 40A. The resistor substrate 48 is held by a substrate holder 53 and a resistor element is formed on its surface. The brush 47 slides on the resistor substrate 48. The illuminating means is comprised of a light emitting device (LED) 49 disposed inside the concaved housing 34 of the bushing 35 along the direction of the feed-through hole 37 of the rotational operation shaft 38 from the recess 42 of the rotor 44, an insulating resin-made holder 50 to hold said LED 49 to a position behind the transparent convex lens 43, and terminal leads 51 for connection with an outside power source for the LED 49. A restriction is placed on the extent of rotational motion of the rotational operation shaft 38 by the stopper 39 which is disposed on the resin-made rotor 44 and is hitting a projection 52 disposed on the lower portion of the concaved housing 34 of the bushing 35. In the same manner as was in the prior art example, a housing box 54 for containing the speed reduction gear mechanism 32 and the motor 33 are mounted behind the substrate holder 53 of the variable resistor 31. The bushing 35, the substrate holder 53, and the housing box 54 are all put together to complete an integral body by means of a U shaped bracket 55 fastened to the motor 33 by screws. The rotational motion of the motor 33 is transmitted to the driver 40 of the variable resistor 31 through the speed reduction gear mechanism 32. When the motor 33 is rotated by application of a voltage, its rotational motion is reduced in speed by the speed reduction gear mechanism 32 and transmitted to the center shaft 40A of the driver 40 in the variable resistor 31 and adjustment of resistance values is performed by sliding of the brush 47 on the resistor substrate 48 which is carried out by rotation of the brush holder 46 inter-linked with said center shaft 40A. At this time, a voltage is applied across the terminals 51 and the LED 49 is activated to emit light. The emitted light is focused by the transparent convex lens 43 at the front, and reflected by the tapered inner surfaces of the feed-through hole 37 of the rotational operation shaft 38, and illuminates an indicator of a knob (not shown in drawings) mounted on the end of the rotational operation shaft 38. The end portion of the rotational operation shaft 38 is flattened to have a cut surface 38A for mounting the knob. on account of this requirement, the feed-through hole 37 is made smaller in its diameter toward its end to get the smaller diameter hole 37B. Further, the speed reduction gear mechanism 32 is formed of a friction clutch 58 comprising a last stage reduction gear 56 and a friction spring 57, and coming into contact with the center shaft 40A of the driver 40. The rotational motion of the motor 33 is transmitted to the driver 40 through the friction clutch 58. In case where the variable resistor 31 is manipulated by rotating the rotational operation shaft 38 by hand, said friction clutch 58 is forced to slip. In other words, the illumination type electronic part of the present invention as defined in claim 1 is characterized by having a rotational operation shaft 38, which is a simple hollowed cylinder, and disposed with an elevated step portion 36 to serve as a stopper against a thrust force, and by preparing a rotor 44 disposed with a stopper 39 for restricting the extent of rotational motion separately from the rotational operation shaft 38, and in addition by use of a molding resin for preparing the rotor 44. According to the foregoing structure, the illumination type electronic part of rotational operation of the present invention and its embodiments defined in the dependent claims have the following effects: The simple hollowed cylindrical shape adopted in the rotational operation shaft has made it possible to cope with changes in specifications for the rotational operation shaft in length, diameter or the like within a short period for low cost since it can be produced easily by machining such as cutting and scraping without the necessity of using dies for die-cast molding or the like. Also, by having an elevated step portion to serve as a stopper against a thrust force disposed on a rotational operation shaft, by having said rotational operation shaft inserted from the front side of a fitting and supporting hole of a bushing and by having a rotor fixed by staking to the rear side of said bushing to prevent its coming off from said rotor, it has become possible not only to enhance the durability in rotational operation against the thrust force that may be applied unexpectedly to the end of the rotational operation shaft when mounting a knob or during the movement of the equipment using said electronic part since from place to place the thrust force is absorbed by the elevated step portion disposed on the periphery of the rotational operation shaft and by the end of bushing's fitting hole, but also to prevent such adverse effects as damages or the like inflicted on other component parts such as the resistor substrate or the like. Besides, by having the rotor, on which a stopper is disposed, made of resin and also the projection of the bushing hit by the resin-made stopper, the hitting sound given forth between the stopper and the bushing has been made small even when the bushing is made of metal by a die-casting method or the like. Accordingly, a silent illumination type electronic part of rotational operation has become available for use in audio equipment or the like. In addition, on account of the light collecting lens disposed on the end of the rotor, the light emitted from the light emitting device in the rear end of the feed-through hole of the rotational operation shaft is intensified by said light collecting lens and the indicator on the end of the rotational operation shaft is illuminated brightly. Also, due to the slight tapering of the feed-through hole of the rotational operation shaft existing between its larger diameter at the rear end and its smaller diameter at the front end, the light is propagated by reflection along the tapered surface walls inside the feed-through hole to light up efficiently the indicator on the end of the rotational operation shaft even if said feed-through hole is small in diameter toward the end of the rotational operation shaft. Further, by having the rotor made of a transparent resin and put together integrally with the light collecting lens, it has become possible not only to facilitate the assembly of the lens but also to illuminate the end portion of the rotational operation shaft more efficiently. Although the case of a motor-driven illumination type variable resistor of rotational operation is described as an exemplary embodiment of the present invention in the foregoing, the present invention can be applied to other various kinds of illumination type electronic parts of rotational operation including a non motor-driven illumination type variable resistor.

Claims: An illumination type electronic part of rotational operation comprising: a driver (40) which is interlinked with a brush holder (46) ; a substrate (48) which is kept in contact with a brush (47) mounted on said brush holder (46) ; a bushing (35) with a concaved housing (34) ; a cylindrical rotational operation shaft (38) which is fitted in and supported by said bushing (35) so as to keep the shaft rotating freely, and in possession of an elevated step portion (36) for stopping a thrust motion of the rotational operation shaft (38) hitting said bushing (35), and also a feed-through hole (37) ; a resin-made rotor (44) which is fixed to the rear end of said rotational operation shaft, and in possession of a stopper means (39) of restricting the extent of rotational motion of said rotational operation shaft, a means of linking with the driver, and a recess in its center; and a light emitting device (49) disposed inside said concaved housing and in the back of said recess of the rotor. The illumination type electronic part of rotational operation according to Claim 1 wherein the rotor is made of a transparent resin, and a light collecting convex lens (43) is formed integrally therewith in front of the recess at the center of said rotor, and also the light emitting device is disposed in the back of the hole located in the center of said rotor. The illumination type electronic part of rotational operation according to Claim 2 wherein the light collecting convex lens of the transparent resin-made rotor and the light emitting device are located toward inside of the rear end of the feed-through hole of the cylindrical rotational operation shaft and also said feed-through hole (37) is gradually changing its diameter from the larger diameter section (37A) in its rear end to the smaller diameter section (37B) in its front end. The illumination type electronic part of rotational operation according to Claim 1 wherein a resistance element is formed on the substrate.

Inventors: MATSUI HIROSHI, MURAKAMI TOMITARO, NAKAGAWA YOSHINOBU, MATSUI, HIROSHI, MURAKAMI, TOMITARO, NAKAGAWA, YOSHINOBU
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1993
Main classification: H01C1
IPC codes: H01C10