Rotating type variable resistor

The rotating type variable resistor includes a housing; a rotating member disposed to be rotatable in the housing; a ring-shaped support member having a conductive pattern at one surface of the support member and disposed at any one side between the housing and the rotating member; and a sliding member disposed at the other side between the housing and the rotating member, and capable of sliding relative to the conductive pattern, wherein the conductive pattern is composed of a high resistor unit containing carbon and a low resistor unit having a specific resistance lower than that of the high resistor unit, and the high resistor unit and the low resistor unit are alternately and repeatedly formed along a direction where the conductive pattern and the sliding member slide.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotating type variable resistor, and in particular, to a structure of a rotating type variable resistor employed for various controllers such as an electronic apparatus especially for the use in a vehicle.

2. Description of the Related Art

A structure of a rotating electric component such as a rotating type variable resistor and an encoder in the related art has a case having a hollow support member and a plurality of contact members (i.e. sliding contacts) embedded in a support unit, an axial member (i.e. rotating member) having a hollow axial unit and being rotatably supported by a case and having a conductive pattern formed in a rotating unit, and a mounting member (i.e. cover member) covering the top of the case (for example, see patent document 1).

Hereinafter, the structure of the rotating electric component of the related art will be described with reference to the accompanying drawings.

FIG. 6is a cross-sectional view illustrating a rotating electric component of the related art, andFIG. 7is a disassembled perspective view illustrating the rotating electric component.

Referring toFIGS. 6 and 7, the case21molded with a synthetic resin has a rectangular support unit21bhaving a ring-shaped concave unit21a, and a cylindrical support unit21dhaving a penetrating hole21cat its center and being perpendicular to the center of the support unit21b, and a plurality of contact members22are embedded as a unit with the terminal in the support unit21bof the case21.

The axial member23molded with a synthetic resin has an axial unit23bhaving a penetrating hole23aat its center, and a ring-shaped rotating member23cformed at the lower end of the axial unit23b, and the axial unit23band the rotating member23care shaped as a unit, and the axial unit23bis shaped like a cylinder having the same diameter throughout the length and thus a straight contour. And a conductive pattern24composed of a resistor or a code pattern is formed at the lower surface of the rotating member23c, and an axial member23having the conductive pattern24inserts the support unit21dto the penetrating hole23a, and the rotating unit23cis received within the concave unit21aso that it is rotatably fitted in to the case21.

A mounting plate25molded with a metal plate has a flat portion25bhaving a hole25a, a pair of legs25crectangularly bent from the flat portion25b, and a plurality of mounting portions25drectangularly bent from the flat portion25b, and the axial unit23band the support unit21dare inserted to the hole25aof the mounting plate25to allow the flat portion25bto cover one surface of the rotating unit23c, and a front end of the leg25cis bent to the lower surface of the case21to allow the case21and the axial member23to fit together, and thus the mounting plate25has the functions of a mounting body and a case.

When a rotating electric component having the above-described configuration rotates the axial portion23bof the axial member23, the rotating unit23cand the conductive pattern24rotate, and the contact piece22slides on and contacts with the conductive pattern24, therefore an output signal is produced.

Further, the rotating electric component of such a configuration is mounted in a printed circuit board (not shown), and a push button switch26is disposed in the printed circuit board positioned within the penetrating hole21cof the case21as shown inFIG. 6. And the support unit21dof the case21and the axial portion23bof the axial member23are cylindrical-shaped, so that another electric component can be disposed in the center space thereof, which yields an electric component having a good space factor.

SUMMARY OF THE INVENTION

However, in the above-described rotating electric component, a rotating unit disposed at the lower end of the axial member and having a conductive pattern is ring-shaped, and is also hollow-shaped to have a large penetrating hole in its center, so that the pattern of the resistor can not be thick, and it becomes elongated, which causes a difficulty in decreasing a total resistance by, for example, about 10 kΩ in order to read a voltage output with an analog to digital (A/D) converter of a central processing unit (CPU). In addition, when a low resistor ink is employed in order to decrease the total resistance, an amount of carbon contained in the ink is increased, which cause the resistor to be weak, so that the sliding lifetime deteriorates from damping etc.

To solve these problems in the conventional method, it is an object of the present invention to provide a rotating type variable resistor capable of reducing a total resistance even when a ring-shaped support member where a conductive pattern such as a resistor is disposed has a hollow shape.

The above object of the present invention is achieved by a first aspect of a rotating type variable resistor, which includes: a housing; a rotating member rotatably disposed in the housing; a ring-shaped support member having a conductive pattern at one surface of the support member and disposed at one of the housing and the rotating member; and a sliding member disposed at the rest of the housing and the rotating member, and capable of sliding relative to the conductive pattern, wherein the conductive pattern is composed of a high resistor unit containing carbon and a low resistor unit having a specific resistance lower than that of the high resistor unit, and the high resistor unit and the low resistor unit are alternately and repeatedly formed along a direction where the conductive pattern and the sliding member slide.

In a second aspect, the high resistor unit is formed of a binder resin in which carbon black and graphite are dispersed. And in a third aspect, the low resistor unit is composed of a silver layer and a carbon layer covering the silver layer, and the carbon layer and the high resistor unit are formed of the same material.

In a fourth aspect, the conductive pattern is arc-shaped such that a summed region of the low resistor units is larger than that of the high resistor units. And in a fifth aspect, the rotating type variable resistor further includes a click body supporting the rotating member at a predetermined position, wherein the rotating member is supported by the click body when the sliding member is in contact with the low resistor unit of the conductive pattern so that a positional relationship between the conductive pattern and the sliding member is kept in a stable state.

According to the present invention as mentioned above, the rotating type variable resistor includes a housing; a rotating member disposed to be rotatable in the housing; a ring-shaped support member having a conductive pattern at one surface of the support member and disposed at one of the housing and the rotating member; and a sliding member disposed at the rest of the housing and the rotating member, and capable of sliding relative to the conductive pattern, wherein the conductive pattern is composed of a high resistor unit containing carbon and a low resistor unit having a specific resistance lower than that of the high resistor unit, and the high resistor unit and the low resistor unit are alternately and repeatedly formed along a direction where the conductive pattern and the sliding member slide, so that a total resistance value of the conductive pattern may be decreased.

In addition, the high resistor unit is formed of a binder resin in which carbon black and graphite are dispersed, so that the total resistance can be further suppressed because of the contained graphite. In addition, the low resistor unit is composed of a silver layer and a carbon layer covering the silver layer, and the carbon layer and the high resistor unit are formed of the same material, so that the formation of the high resistor unit and the carbon layer covering the silver layer can be performed with the same process, which allows the productivity to be enhanced.

In addition, the conductive pattern is arc-shaped such that the entire region of the low resistor units is larger than that of the high resistor units, so that the total resistance of the conductive pattern can be further suppressed from being increased because of the larger summed region of the low resistor unit.

In addition, the rotating type variable resistor further includes a click body supporting the rotating member at a predetermined position, wherein the rotating member is supported by the click body when the sliding member is in contact with the low resistor unit of the conductive pattern so that a positional relationship between the conductive pattern and the sliding member is kept in a stable state by the click body, which does not yield a significant output change in the clicked position so that a stable output is obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention regarding the rotating type variable resistor will be described with reference toFIGS. 1 to 5.

FIG. 1is a disassembled perspective view illustrating a rotating type variable resistor of the present invention,FIG. 2is a plan view illustrating a rotating type variable resistor of the present invention,FIG. 3is a front view illustrating a rotating type variable resistor of the present invention,FIG. 4is a lateral cross-sectional view illustrating a rotating type variable resistor of the present invention, andFIG. 5is a plan view illustrating a conductive pattern and a support unit of the present invention.

Referring toFIGS. 1 to 4, the housing1is formed of an insulating material such as a synthetic resin, and has a substantially circular support unit1aand a cylindrical axis1bprotruded at the center of the support unit1a. The support unit1ais shaped like a box having an opening at its front surface (the top surface inFIG. 4), and a concave-shaped receiving unit1cin its inside. In addition, at the top and bottom positions of an inner wall facing to the cylindrical axis1bin the receiving unit1cofFIG. 1, a pair of concave engagements1dand1ewhich engage protrusion units2band2cof the support member2described later is provided, and at one end of the inner bottom surface of the engagement concave unit1e, a terminal hole1fwhich allows the connection terminal5of the support member2to protrude toward the bottom surface of the housing1is provided.

In addition, at the external portion of the support unit1a, a plurality of outward protruding legs1g, and a plurality of concave grooves1hare provided, and a locking piece8bof a cover member8described later is engaged with the concave groove1hso that the cover member8is mounted in the housing1. In addition, the cylindrical axis1bis hollow, and has a large penetrating hole1iin its center. At the inner wall of the penetrating hole1i, a plurality of guide grooves1jare provided in up and down directions ofFIG. 4, and a manipulating knob of an electronic apparatus (not shown) is mounted to be capable of moving up and down in the guide groove1j, which is also manipulated by a push button switch within the hollow center mounted on a printed circuit board which is not shown.

As such, a large penetrating hole1iis provided at the center of the housing1, and the cylindrical axis1bis hollow so that another electric component can be disposed in the center space, which allows a rotating type variable resistor having a good space factor to be obtained when it is used in a printed circuit board or the like.

The support member2is composed of a resin-stacked plate such as a phenol resin, and is ring-shaped which has a large opening2ain its center. In addition, at the top and bottom positions of the support member2ofFIG. 2, a pair of protrusion units2band2cprotruding outward are provided, and the protrusion units2band2care engaged with the pair of concave engagement units1dand1eprovided within the receiving unit1cof the housing1so that the support member2is positioned within the receiving unit1c.

In addition, at one surface (e.g. the top surface) of the support member2, a common pattern3as a ring-shaped current collecting body formed of a conductive material such as silver, and an arc-shaped conductive pattern4as a resistor formed of a conductive material such as carbon along the circumference of the common pattern3are provided. In addition, at the center of the protrusion unit2c, an electrode3aprotruding from the common pattern3is provided, and a pair of electrodes4aand4aprotruding from both ends of the conductive pattern4are provided at both sides of the electrode3ainterposed between the electrodes.

In addition, connection terminals5are fixed to the electrodes3a,4a, and4a, and these connection terminals5protrude outward from the terminal hole1fprovided at one end of the inner bottom surface of the receiving unit1c. And these connection terminals5are connected to the interconnection pattern on the printed circuit board of an electronic apparatus which is not shown.

In addition, the common pattern3is continuously formed to be ring-shaped with a conductive material such as a silver layer. In addition, the conductive pattern4is formed such that a high resistor unit4b(hatched portion) and a low resistor unit4chaving a specific resistance lower than that of the high resistor unit4bare alternately and repeatedly formed as shown inFIG. 5. The high resistor unit4bis formed of a binder resin in which carbon black, and graphite having an effect of decreasing the resistance is dispersed. By means of the contained graphite, the total resistance can be further suppressed.

In addition, the low resistor unit is composed of a silver layer and a carbon layer covering the silver layer. And in the present embodiment, the carbon layer is formed of the same material as that forming the high resistor unit4b, so that the formation of the high resistor unit4band the carbon layer covering the silver layer of the low resistor unit4ccan be performed with the same process, which allows the productivity to be enhanced. In addition, the common pattern3is composed of two-layered structure having a silver layer and a carbon layer covering the silver layer, which has the same material and configuration as the low resistor unit4c.

In addition, the conductive pattern4is arch-shaped, and a sliding member7fixed to the rotating member6described later slides on the conductive pattern4, wherein the conductive pattern4is formed such that a summed region (summed angle) of the low resistor units4cis larger than that (summed angle) of the high resistor units4b. In this case, both ends connected to the electrodes4aand4aalso constitute a portion of the conductive pattern4and are included in the region of the low resistor unit4c. In addition, in the present embodiment, each length in the circumferential direction of the low resistor unit4cis longer than that in the circumferential direction of the high resistor unit4b, and a sliding region where the sliding member7and the conductive pattern4slide is larger in the entire sliding region of the low resistor units4cthan in the entire sliding region of the high resistor units4b.

As such, the summed region of the low resistor units4cis larger than that of the high resistor units4b, so that the total resistance of the conductive pattern4can be further suppressed.

The rotating member6is formed of an insulating material such as a synthetic resin, and has a ring-shaped rotating plate6aand a rotating axis6bcylindrically protruding at the center of the rotating plate6a. At the bottom surface of the rotating plate6a, a sliding member7composed of a conductive metal plate is provided, which is in elastically contact with the conductive pattern4and the common pattern3of the support member2, and slides on the conductive pattern4and the common pattern3in response to the rotation of the rotating member6. In addition, at the top surface of the rotating plate6a, is built a click cam unit6cthat is composed of concavities and convexities continued in a circular shape.

In addition, the rotating axis6bis hollow and a large engagement hole6dis provided in the center of the rotating axis6b. A plurality of click units6eprotruding outward are provided at the top surface of an external portion of the rotating axis6b, and guide protrusion units6fprotruding outward are provided along the up and down directions of the lower surface from its center.

The engagement hole6of the rotating axis6bis engaged with the cylindrical axis1bof the housing1in the rotating member6so that the rotating plate6ais rotatably received within the receiving unit1c. In this case, the sliding member7fixed at the bottom surface of the rotating plate6ais in contact with the conductive pattern4and the common pattern3of the support member2positioned within the receiving unit1cso that it can slide. And a manipulating knob of an electronic apparatus or the like which is not shown is engaged with the guide protrusion unit6fand the click unit6eof the rotating axis6bso that the rotating member6is rotatably manipulated in response to the rotation manipulation of the manipulating knob.

The cover member8sis formed such that a thin metal plate is punched and bent, and has a ring-shaped cover8a, a plurality of locking pieces8bextended downward from the cover8a, a pair of snap pieces8copposing to each other, and a pair of guide pieces8dopposing to each other in a different direction from the opposing direction of the snap pieces. In addition, a protruded fixing unit8ewhich fixes a click plate9described later is provided on the cover8a.

The cover member8is mounted in the housing1such that a plurality of locking pieces8bare engaged with the plurality of concave grooves1hprovided at the external portion of the housing1to allow their front ends to be cocked so that the opening of the receiving unit1cis covered. In addition, the pair of the guide plates8dis engaged with the concave engagement units1dand1eof the receiving unit1cwhile the protrusion units2band2cof the support member2are pressed so that the support member2is securely interposed and positioned therebetween. In addition, the pair of the snap pieces8cextend downward to the bottom surface from the external surface of the housing1so that it is snapped with a mounting hole of a printed circuit board such as an electronic apparatus which is not shown. In this case, the legs1gof the housing1can be securely fixed by means of screws or the like if necessary.

The click plate9is arc-shaped with an elastic thin metal plate, and an engagement hole9ais provided at both ends of the click plate to engage the fixing unit9eof the cover member8, and a protrusion unit9bwhich protrudes downward is provided at the center of the click plate. When the rotating member6is rotated, the protrusion unit9bslides on and contacts with the click cam unit6chaving an uneven structure formed on the top surface of the rotating plate6aof the rotating member6so that a click feedback is provided.

In this case, when the protrusion unit9bis positioned at the concave portion of the click cam unit6c, the rotating member6is kept at its current position in a stable state, and the sliding member7is in contact with the low resistor unit4cof the conductive pattern4in this stable state. As such, when the sliding member7is in contact with the low resistor unit4c, the stable state is kept by means of the click body which is composed of the click plate9and the click cam unit6c, so that a significant output change does not occur in the click-pausing state, the stable state (at the position of the concave portion), which yields a stable output.

In addition, in the above-described embodiment, the support member2provided with the conductive pattern4is received and positioned within the receiving unit1cof the housing1, and the sliding member7which slides with the conductive pattern4is fixed to the rotating member6, however, the present invention is not limited thereto, the sliding member7may be fixed to the receiving unit1cof the housing1, and the support member2provided with the conductive pattern4may also be fixed to the rotating member6.

In addition, the support member2is composed of a resin-stacked plate such as phenol resin, however, it may be ring-shaped with an insulating material such as FPC or a synthetic resin, and the common pattern3and the conductive pattern4may be formed in this support member. In addition, the housing1and the support member2may be formed as one body to allow the housing with the function of the support member2to be provided with the conductive pattern. In addition, in the above-described embodiment, the housing1is described as one member which has the receiving unit1c, however, the housing may be formed to have two members such as a plate-shaped member and a frame-shaped member, and in this case, a function of the support member2may be provided to the plate-shaped member, which can form the conductive pattern in the plate-shaped member.

According to the above-described embodiment, the rotating type variable resistor has the ring-shaped support member2having the conductive pattern4on one surface, and the sliding member7which can slide relative to the conductive pattern4, and the conductive pattern4is composed of the high resistor unit4bcontaining carbon and the low resistor unit4chaving a specific resistance lower than that of the high resistor unit4b, and the high resistor unit4band the low resistor unit4care alternately and repeatedly formed along a direction where the conductive pattern4and the sliding member7slide, wherein each of the low resistor units4cis disposed between the high resistor units4bat predetermined intervals along the sliding direction of the conductive pattern4, so that the total resistance of the conductive pattern4can be decreased.

Accordingly, by means of the ring-shaped (i.e. circular ring-shaped) support member2having a large opening2ain its center in the above-described embodiment, the total resistor value of the conductive pattern (resistor) can be decreased by, for example, about 10 kΩ even when the width of the conductive pattern4(resistor) cannot be increased.