Murata Manufacturing Co., Ltd.

Yukinori Ueda

Fumitoshi Masuda

Hiroyuki Kishishita

Katsuhiro Onishi

Hideaki Tsukada

Kiminori Yamauchi

Kenji Matsui

Takeshi Doi

Yukio Hatanaka

Toshi Numata

Motohiro Kinoshita

Hideo Nishizawa

Yoshiyuki Nakatsu

Tomohisa Ogawa

Hong Eui Choi

Kiyoshi Ito

Miroyuki Kishishita

Kunio Ito

A detection device and a rotation angle sensor include a case body and a cover member. A support portion in the case body is provided with fitting protuberances fitted in fitting holes of a printed board, on which a detection component is mounted, so as to position the printed board. Each protuberance has ribs protruding from an outer peripheral surface thereof. The ribs are elastically or plastically deformed by contact with an inner peripheral surface of the corresponding fitting hole of the board, and position the board along a support surface of the support portion. A projecting portion of the cover member is elastically or plastically deformed so as to urge the board toward the support surface of the support portion so that the board is clamped between the projecting portion and the support surface and is positioned in a direction perpendicular to the support surface of the support portion.

Detection device and rotation angle sensor

A thin-thickness variable resistor is provided, which is capable of stabilizing electrical connection between metallic terminals and a resistor by increasing the holding strength for a second terminal by a substrate while preventing the bending strain during the bending work from spreading to a conductive portion conductive to the resistor. A variable resistor comprises a substrate, metallic terminals formed in the substrate by insert-molding, and a slider sliding on a resistor formed on the substrate, wherein the slider is rotatably attached by crimping an eyelet formed in a first metallic terminal. External-connecting portions of the metallic terminals are extended from the bottom portion of the substrate to be bent upwardly along sides of the substrate. Anchor portions to be embedded into the substrate are unitarily formed in the vicinity of the conductive portions of the second metallic terminals conductive to the resistor and between the conductive portions of the second metallic terminals and the external connection portions thereof.

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 includes at least two sliders fixed to the bottom of the concavity of a case, a rotor having an engaging portion for engagement with a tool, on the upper side thereof and rotatably received in the concavity of the case, a resistor substrate having a resistor and an electrode on the underside thereof, capable of being sliding-contacted with the slider, and attached to the underside of the rotor, a cover attached to the opening of the concavity of the case and held in such a manner that the rotor is restrained from rising and is rotatable, and an o ring performing the seal between the inner peripheral surface of the concavity of the case and the outer peripheral surface of the rotor. The rotor has a step portion formed in the outer peripheral surface on the underside thereof with the lower-side portion of the step portion having a short diameter. The resistor substrate is formed into a disk-shape having a diameter longer than that of the short diameter portion of the step portion of the rotor. The O ring is prevented from being released by fixing the resistor substrate to the underside of the rotor.

A variable capacitor includes a driver member including one metal sheet, a head having a driver groove provided therein, engagement portions engaged with a rotor, and a spring function portion in pressure-contact with the rotor are integral with each other. The spring function portion includes a first plate portion extending from one end of the head, which is bent in the first bending portion, and elongated, passing a center shaft, and a second plate portion extending from the end of the first plate portion, which is bent in the second bending portion, and elongated, passing the center shaft. The second plate portion functions as a pressure-contact portion for the rotor.

Variable capacitor

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.

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.

Manufacture of a metal rotor for a trimmer capacitor using cold forging or casting conventionally requires a metal mold to be exclusively used for the metal rotor, which incurs costs associated with the fabrication and maintenance of the mold. According to the invention, however, a metal rotor can be obtained by etching instead of cold forging or casting. Specifically, a metal plate is provided which has a principal surface with a predetermined degree of smoothness for a surface of a rotor electrode. The metal plate is selectively etched using resists, to form a step portion, a driver groove and a circumferential surface for the rotor electrode, which are the components of the metal rotor.

Method of manufacturing metal rotor for trimmer capacitor

In a variable capacitor having a stator with a stator electrode and a rotor with a rotor electrode both of which are housed in a recess section of a casing while allowing the recess section to be closed by a cover, enabling the rotor to be brought into stable close contact with the stator. To this end, a cover (46) made of a chosen metal includes a cover main body (55) which covers the upper opening of a recess section (45) except for an adjustment hole (54) that exposes a driver groove (30) of the rotor (43), leg sections (56, 57) which engage a casing (44) letting the cover main body (55) be secured to the casing (44), and a rotor terminal. The cover main body (55) has a size corresponding to the outer diameter of the variable capacitor (41). This cover main body (55) may have a vent shape so as to create intended elastic force which may act to compress the rotor (43) against the stator (42). More preferably, a spring washer (60) is provided which integrally extends from the cover main body (55) and is folded so that it is placed between the cover main body (55) and the rotor (43).

There is provided a variable resistor having a small number of parts and having an excellent heat releasing property. A rotor is rotatably contained in a concave portion of a case. The rotor has a resistive element provided on the bottom thereof and electrodes connected to both ends of the resistive element. Arms of sliders are provided on the bottom of the concave portion of the case in a sliding relationship with the respective electrodes and resistive element. A metal cover is disposed on the upper surface of the case in contact with the rotor.

In order to prevent flux which is employed for soldering an open type pre-set variable resistor from reaching an upper major surface of a substrate provided with a resistor film, a blocking member is formed in a position upwardly separated from a lower major surface of the substrate by a prescribed distance, to block a through hole provided in the substrate. Further, an engaging portion which is provided on a variable side terminal is located in a position downwardly separated from the upper major surface of the substrate by a prescribed distance, to hold a slider which is rotatable about the central axis of the through hole.

A method of manufacturing an electronic component having a concave portion. A ceramic laminate is prepared having a plurality of sheets with burnaway film formed thereon. The burnaway film material is capable of being burned away by firing. The burnaway film is provided in layers in positions corresponding to the desired position of the concave portion. Firing the ceramic laminate burns out the burnaway film, and a sintered body is formed with a plurality of cavities provided in layers between a plurality of thin laminate layers. Crushing the thin layers of the sintered body forms the concave portion.

Method of providing a sintered ceramic body having a concave portion

In order to obtain a stator of a variable capacitor, prepared is a ceramic laminate having a stator electrode provided in its interior and a plurality of burnaway films of carbon or resin, which can be burned away by firing, provided in positions corresponding to that of a concave portion in the form of layers. This ceramic laminate is fired to burn out the burnaway films thereby obtaining a sintered body provided with a plurality of cavities and a plurality of thin layers, and this sintered body is barrel-polished to crush the thin layers, thereby forming a concave portion. A rotor of a metal forming a rotor electrode is arranged on the stator obtained in the aforementioned manner. A cover of a metal is fixed to the stator through an engaging member engaging in the concave portion of the stator, to rotatably store the rotor while pressing the rotor against the stator by a spring action part.

A variable resistor includes a sliding member having an arm in contact with a substantially circular arc-shaped resistor provided on a substrate and a driver plate portion from which the arm extends. The sliding member is rotatable by a driver, the center of the resistor being a supporting point of the sliding member. The driver plate portion of the sliding member is substantially conical and has driver grooves. The arm is connected to the driver plate portion at both sides of a driver groove adjacent an end of the driver groove. Adjustment of a resistance value is performed by rotating the sliding member with a driver tip inserted in the driver grooves.

A variable resistor of the type having a substantially curved resistor provided on a substrate has an arm portion of a sliding member contacting therewith, the sliding member being rotatable, with a central portion of the resistor as a supporting point, for adjusting the resistance value by rotating the sliding member with a driver. A driver plate of the sliding member is formed substantially into a cone in shape, in which cone a driver groove portion is provided. The driver tip is guided by the conic portion and inserted into the driver groove portion.

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Fukui-ken, Japan

Yukinori Ueda