Murata Manufacturing Co., Ltd.

Fumitoshi Masuda

Yukinori Ueda

Kiminori Yamauchi

Katsuhiro Onishi

Hideaki Tsukada

Motohiro Kinoshita

Masanori Oshima

Hiromu Okunishi

Shigeki Takahashi

Kenji Matsui

Masashi Morikami

Hiroyuki Watanabe

Minoru Yamaguchi

Tomohisa Ogawa

Toru Ogata

Yutaka Kitamura

A variable resistor is constructed to reliably seal the space between a rotor and a substrate without insert-molding the substrate into a case, and to be produced at a very low cost. This variable resistor includes a hollow square-prism shaped case which is open at the top and the bottom, a substrate which is fitted into the lower opening of the case, and on the top surface of which a collector electrode and an arcuate resistor are provided, a rotor rotatably fitted into the upper opening of the case, a slider mounted on the bottom surface of the rotor and making sliding contact with the collector electrode and the resistor, an annular packing member disposed between the rotor and the substrate for sealing the space therebetween, terminals mounted on the substrate and electrically connected to the resistor and the collector electrode, and a metallic cover.

Variable resistor

A first rotor and a second rotor are prepared. The first rotor has a resistor and inner-peripheral and outer-peripheral electrodes respectively connected to end portions of this resistor. The second rotor has a resistor and inner-peripheral and outer-peripheral electrodes symmetrical with those of the first rotor, provided at a position corresponding to that obtained by rotating the first rotor about the axis of the first rotor by an angle of 180&deg; with respect to the first rotor. A variable resistor selectively uses either one of the first rotor and second rotor. This makes it possible to provide a variable resistor which requires few parts. Also, this makes it possible to reduce the kinds of bending operations that must be performed on the terminals.

A variable resistor comprises a case, slide contactors, a rotor, a metal cover and lead terminals. Arms which are respectively provided at central portions of the slide contactors protrude from a bottom surface of a recess portion of the case and are each shaped like a comb. The arms are respectively contacted, at contact portions A, B and C, by electrodes and resistor of the rotor. Lead terminals are each circular in cross section and are respectively connected, at end surfaces of their lead wires, to the slide contactors. This makes it possible to obtain a variable resistor which is easy to manufacture, low in cost and excellent in reliability.

Slack in the engagement of a shaft 5 and a rotor 3 in a case 1 is prevented by the resiliency of an O ring 6 under radial but not axial compression. Even if heat stress is added, the variable resistor which can secure air-tightness is provided. The rotor 3 and a slider 4 are accommodated in the case 1. A resistance substrate 2 having a collector electrode 25 formed on the central portion of the surface and a circular resistor 24 formed concentrically on the periphery of the collector electrode 25 is engaged with the lower end part of the case 1. A stepped surface 12 supporting the peripheral surface and the bottom surface of the O ring 6 is formed on the upper surface of the case. A boss portion 55 contacting the inner circumference of the O ring 6 and an operating portion 51 projecting on the upper surface of the case 1 and covering the stepped surface 12 is formed on the shaft 5. The inner and outer circumferences of the O ring 6 are pressed and contacted with the stepped surface 12 of the case and the boss portion 55 of the shaft 5. A gap .delta. is provided between either upper or lower end surface of the O ring 6 and the stepped surface 12 or the bottom surface of the operating portion 51.

A first rotor and a second rotor are prepared. The first rotor has a resistor and inner-peripheral and outer-peripheral electrodes respectively connected to end portions of this resistor. The second rotor has a resistor and inner-peripheral and outer-peripheral electrodes symmetrical with those of the first rotor, provided at a position corresponding to that obtained by rotating the first rotor about the axis of the first rotor by an angle of 180.degree. with respect to the first rotor. A variable resistor selectively uses either one of the first rotor and second rotor. This makes it possible to provide a variable resistor which requires few parts. Also, this makes it possible to reduce the kinds of bending operations that must be performed on the terminals.

A variable resistor reduces an inclination of a rotor caused by spring reaction of a slider, and prevents the lowering of contact pressure and deterioration in sliding performance of the slider. The resistor includes a rotor 3 and a slider 4 inside a case 1. The variable resistor also includes a resistor substrate 2 having a collector electrode 25 at a central portion of a surface thereof and having a resistive element 24 in a circular arc shape on an outer side of the collector electrode 25 substantially concentric with the central portion. The resistor substrate 2 is mounted to a lower end portion of the case 1. The slider 4 is provided with a first arm 42 having a substantially U-like shape at one end side of a base portion 41 attached to the rotor 3, having a first contact point portion 42a at a front end of the first arm which is brought into sliding contact with the resistive element 24 in the circular arc shape. The slider 4 is also provided with a second arm 43 and a second contact point portion 43a at a front end of the second arm which is brought into contact with the collector electrode. The arms are bent in directions opposed to each other, wherein the slider 4 is formed such that the first contact point portion 42a is disposed on the inner side of base portion 41 from a folded-bent portion 43b of the second arm 43, and the second contact point portion 43a is disposed on the inner side of the base portion 41 from a folded-bent portion 42b of the first arm 42. The second contact point portion 43a is folded back to the side of the resistor substrate 2.

A variable resistor comprises a slider body, a contact arm which is provided to project from the slider body, a contact part which is formed by bending the contact arm, an arcuate spring arm having a projection for engaging with an engaging portion of a rotor gear, and a stopper which is formed by bending a stopper member provided to project from the slider body. The arcuate spring arm has an inboard structure connected with the slider body at both ends thereof. The projection engages with the engaging portion of the rotor gear, so that the slider body is rotated following rotation of the rotor gear. When the rotor gear is further rotated in such a state that the stopper comes into contact with a case side stopper which is formed on a case thereby inhibiting the slider body from rotation, the engagement between the engaging portion and the projection is released. Thus, the slider body is prevented from overrotation.

Variable resistor having clutch mechanism

A movable electrode is positioned between two fixed electrodes. The movable electrode is rotated in correspondence to a rotation angle to be detected. The fixed electrodes and the movable electrode are split into first split electrode members and second split electrode members not conducting with each other respectively. The first fixed split electrode members are electrically connected with a first external terminal, and the second fixed split electrode members are electrically connected with a second external terminal. Thus, electrostatic capacitances which are derived from the external terminals are varied by rotation of the movable electrode. In this sensor, the varied electrostatic capacitances can be derived through conductive paths comprising no sliding contact portions, while a variable range of the electrostatic capacitances can be increased.

Capacitance type rotation angle sensor

A wiper and a rotor are held to be rotatable with respect to a substrate which is provided on its one major surface with an arcuately extending resistive element. A contact member sliding along the resistive element is formed by bending a portion integrally extending from a wiper body. The wiper is integrally provided with a detent member, which is so formed as to bridge two points of a peripheral edge portion of the wiper body. The detent member engages with the rotor, thereby providing a clutch mechanism for stably transmitting rotation of the rotor to the wiper for rotating the rotor and the wiper along with each other until the wiper is inhibited from the rotation.

First and second fixed electrodes are fixedly provided on a housing which is mounted on a surface whose inclination angle is to be detected. A rotatable electrode is inserted between these fixed electrodes, and this rotatable electrode is mounted on a shaft which is rotatably provided on the housing. The rotatable electrode is made to regularly face a constant direction with respect to the gravitational direction. The first fixed electrode has a central angle of 180.degree., for example, and is split into a first fixed split electrode member having a central angle of 60.degree. and a second fixed split electrode member having a central angle of 120.degree.. Wires are connected to the fixed split electrode members respectively, thereby taking out two series-connected capacitances which are formed by the respective ones of the first and second fixed split electrode members and the rotatable electrode. The second fixed electrode is structured similarly to the first fixed electrode. Thus, it is possible to detect the inclination angle of the surface to be measured on the basis of the capacitances.

Inclination angle sensor

A variable resistor having an insulating substate provided on the surface thereof with a resistor is molded into a resin case, a part of which is heated and bent to rotatably secure a rotor having a sliding member within the case for rotation with respect to the insulating substrate. The insulating substrate is molded into the resin case to make inside of the case airtight. An annular elastic body mounted between the under surface of a skirt portion of the rotor and the insulating substrate makes the space between the rotor and the insulating substrate airtight, and, at the same time, sets the rotational torque of the rotor to a suitable value. The arrangement of the insulating substrate, the resin case and the rotor having the sliding member, reduces the number of parts used for assembling the variable resistor, and together with the use of continuous strip hoop materials for forming terminals and the sliding member, allows for continuous automated production of the variable resistors.

The invention is directed to an electronic component including a casing which is formed by molding a resin material around the stator and the rotor, the rotor being partially exposed through the casing, wherein at least a portion of the surface of the rotor which is in contact with the casing is subjected to a mold releasing treatment, so that the rotor is freely rotatable with respect to the stator and the casing.

Method of molding a casing on a rotary electric component

A variable resistor and a method for manufacturing the same is disclosed in which the variable resistor includes a casing having a bottom wall and a plurality of sidewalls extending from the bottom wall to define an opening of the casing. An insulating substrate is provided having a first surface formed along the bottom wall of the casing and a second surface opposite the first surface facing the opening of the casing. A curved resistor layer and a centrally disposed collector electrode layer are formed on the second surface of the insulating substrate. A rotor member is rotatively disposed within the casing such that its rotation axis extends through the centrally disposed collector layer. A slidable member is connected to the rotor member and is slidably connected to the curved resistor layer and the collector electrode layer for electrically connecting the curved resistor layer and the collector electrode layer. The rotor member is secured within the casing by the sidewalls which are molded to extend inwardly towards the rotational axis defined by the rotor member.

Variable resistor and manufacturing method for the same

A variable resistor whose resistance is adjustable by rotating a rotor on an insulating substrate having an arcuate resistive element. The rotor is formed of an insulating resin and includes an inner skirt and an outer skirt extending from a bottom surface thereof. The inner skirt contacts the upper surface of the insulating substrate inside the arcuate resistive element. A metallic slider is integrated with the rotor by insert molding. The slider comprises a base formed of a metal plate folded at least into two, and arms having contacts at the tips thereof for slidably contacting the resistive element on the insulating substrate. The arms are folded along lines which are parallel to a line extending from the center of the base to the contacts of the arms to cause the contacts to project toward the insulating substrate. One of the metal plates forming the base cooperates with the inner and outer skirts of the rotor to seal a space accommodating the resistive element and the arms of the slider. External electrodes formed on the insulating substrate, with each of them connected with the resistive element, comprises a lower layer of silver, an intermediate layer of nickel or a nickel alloy, and an upper layer of tin or a tin-lead alloy.

Growing community of inventors

Fukui-ken, Japan

Fumitoshi Masuda