WATERPROOF CODING DEVICE WITH BUILT-IN MAGNETIC DISC

A waterproof coding device with a built-in magnetic disc, comprising: a magnetic disc; a knob with a shaft, elastic positioning pieces and a magnet conducting ring; a positioning shaft, the magnetic disc and an inductive circuit board being mounted on the positioning shaft; and, a circular support base being located above a panel, the wall of the base is provided with positioning grooves; the head part of the positioning shaft is penetrated through the panel to be screwed; the knob is mounted on the base, the shaft is movably fitted with a sleeve inside the base, the magnet conducting ring is gripped by magnets on the magnetic disc so that the magnetic disc can rotate synchronously with the knob. The coding device has the advantages of compact structure, water tightness and shock resistance, and is specifically suitable for applications in high-humidity environments and occasions with high shock possibility.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

The invention will be further described as below by embodiments with reference to the drawings.

Referring toFIG. 1toFIG. 3, Embodiment 1 provides a waterproof coding device with a built-in magnetic disc, mainly comprising: a knob10with a magnetic conducting ring13, a circular support base20, a positioning shaft50, a magnetic disc60, an inductive circuit board70, a waterproof sealing gasket30between the circular support base20and a panel40, etc.

The magnetic disc60comprises a plastic disc, in the middle of which an installation hole (used for installing a bearing or shaft collar61) is provided. Eight cavities, in each one of which one cylindrical magnet62is inlaid, are spaced-apart in an approximate periphery part on the same circumerence. Two adjacent magnets62on the magnetic disc60have opposite polarities. The cylindrical magnets may be neodymium-iron-boron magnets, etc.

The magnetic disc60may also be molded from the mixture of plastics and magnetizing powders, and a number of magnets62are distributed at internals in the approximate periphery part of the magnetic disc60by means of partial magnetizing.

The inductive circuit board70is provided thereon with a flat center hole73and two Hall elements (or magnetically sensitive tubes)71for detecting signals representing angular displacement between the knob and the magnetic disc. The two Hall elements are distributed on one circumference corresponding to the eight magnets62on the magnetic disc60, and an included angle between two lines of the two Hall elements and a circle center is 22.5°.

The peripheral wall of the circular support base20is provided thereon with a plurality of positioning grooves22. A sleeve23(acting as a shaft sleeve) is provided in the center of the circular support base20.

The positioning shaft50ofFIG. 3comprises a head part51with a screw hole52, a middle part55, a check ring54between the head part51and the middle part55, and a tail part56. The magnetic disc60is mounted in the middle part55of the positioning shaft50by a bearing or shaft collar61. The inductive circuit board70is screwed at the tail part56of the positioning shaft50by a fastener80(for example, a bolt, a gasket). The upper end of the heat part51of the positioning shaft50is provided with a first positioning plane53that is fitted with an external axle hole with a positioning face on the bottom surface of the sleeve23in the circular support base20, while a threaded section at the tail part56thereof is provided thereon with a second positioning plane57that is fitted with the flat center hole73of the inductive circuit board70, to ensure the initial positions of the magnetically sensitive element71of the inductive circuit board70and the positioning grooves22on the circular support base20. The circular support base20is located above the panel40(for example, a plastic panel, an aluminum panel, etc.). The head part51of the positioning shaft50is penetrated through the installation hole41on the panel40and the waterproof sealing gasket30from inside to outside. The first positioning plane53of the heat part51is fitted with the external axle hole (not shown) with a positioning face on the bottom surface of the sleeve23in the circular support base20, and screwed with the screw hole52of the head part51of the positioning shaft50by a fastening screw21in the sleeve23.

The middle part of the inner top surface of the knob10is provided therein with a shaft11. On the inner top surface of the knob10, 2 or 4 elastic positioning pieces12extend downward around the shaft11, and lower ends of the elastic positioning pieces12are provided with protrusion portions for fitting and positioning the corresponding positioning grooves22on the peripheral wall of the circular support base20. An outer wall of the knob10is provided thereon with an annular cavity, and the magnetic conducting ring13is provided at an opening of the annular cavity. The knob10is mounted on the circular support base20. The shaft11of the knob10is movably fitted with the sleeve23in the circular support base20. The elastic positioning pieces12of the knob10correspond to the corresponding positioning grooves22on the periphery of the circular support base (the positioning grooves22are fitted with the protrusion portions of the elastic positioning pieces12). The magnetic conducting ring13is gripped by the plurality of magnets62on the magnetic disc60so that the magnetic disc60can rotate synchronously with the knob10. When the magnetic disc60rotates synchronously with the knob10, the two Hall elements71on the inductive circuit board70output pulse-coded signals representing angular displacement between the knob and the magnetic disc.

The top surface profile of the circular support base20is a circular arc. The circular arc and the inner top surface of the knob10form a waterproof sealing line. A positioning ring may also be provided on the inner top surface of the knob10, and the edge of the collar of the positioning ring extends downward to form a plurality of elastic positioning pieces12with protrusion portions.

In Embodiment 1 described above, the magnetic disc60and the inductive circuit board70built in the panel of the chassis are mounted and positioned by the positioning shaft50, so that the inductive circuit board is closer to the magnetic disc, which is advantageous to increase the amplitude of output signals of the Hall elements71and reduce the cost of amplification processing for backward signals. The distance from the lower surfaces of the magnets62on the magnet disc60to the Hall elements71on the inductive circuit board70is 0.2-3.5 mm, preferably 0.5-2 mm.

Embodiment 2 provides a waterproof coding device with a built-in magnetic disc, referring toFIG. 4andFIG. 5. Embodiment 2 has a major structure basically the same as Embodiment 1, mainly comprising a knob10with a magnetic conducting ring13, a circular support base20, a positioning shaft50, a magnetic disc60, an inductive circuit board70, a waterproof sealing gasket30between the circular support base20and a panel40, etc.

The difference is that Embodiment 2 has a shaft11′ with a screw as shown inFIG. 5. The shaft11′ with a screw comprises a shaft111′ and a screw112′ extended from one end of the shaft111′. The shaft11′ with a screw is used for replacing the shaft11of the knob10and the fastening screw21in Embodiment 10

With the use of the shaft11′ with a screw, the knob10changes somewhat. In the middle part of the inner top surface of the knob10, a shaft sleeve15extends downward. The inner top surface of the knob10is riveted with four elastic positioning pieces12around the shaft sleeve15. The elastic positioning pieces12are impact molded from elastic metal sheets. The lower ends of the elastic positioning pieces12are provided with protrusion portions fitted with the corresponding positioning grooves22on the peripheral wall of the circular support base20. The outer wall of the knob10is still provided thereon with an annular cavity. The magnetic conducting ring13is provided at an opening of the annular cavity.

Similar to Embodiment 1, the magnetic disc60is mounted in the middle part of the positioning shaft50by a bearing61. The inductive circuit board70is fixed at the tail part of the positioning shaft50by a fastener80. The circular support base20is located above the panel40. The head part of the positioning shaft50is penetrated through the installation hole of the panel40and the waterproof sealing gasket30from inside to outside of the chassis. The first positioning plane of the head part is fitted with the external axle hole (not shown) with a positioning face on the bottom surface of the sleeve23in the circular support base20to be screwed inside the sleeve23with the head part of the positioning shaft50by the screw112′ of the shaft11′ with a screw.

The knob10is mounted on the circular support base20. The shaft sleeve15of the knob10is movably fitted with the shaft11′ with a screw. The elastic positioning pieces12of the knob10correspond to the corresponding positioning grooves22on the peripheral wall of the circular support base20. The magnetic conducting ring13is gripped by the plurality of magnets62on the magnetic disc60so that the magnetic disc60can rotate synchronously with the knob10.

InFIG. 4, the top surface of the circular support base20is in line contact with the inner top surface of the knob10to form a waterproof sealing line.

The embodiments instanced above and descriptions thereof are only provided for describing the invention in details, and should not be regarded as any restriction to the invention. All of various alternative designs made depending on the listed scope of the claims should fall into the patent scope of the invention.