Small rotary encoder

Details Small rotary encoder Small rotary encoder

2000-11-29

2002-05-21

Friedhofer, Michael (Department: 2832)

Electricity: circuit makers and breakers

Multiple circuit control

Pivoted contact

C200S0110TC, C200S564000, C200S570000, C200S336000, C200S004000

Reexamination Certificate

active

06392168

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to rotary encoders that are used in, for example, computer terminal devices, portable communication devices, or sound devices.
2. Description of the Related Art
The structure of a conventional rotary encoder will be described with reference to
FIGS. 51-55
. As best seen in
FIG. 53
, an insulating base
51
molded out of synthetic resin includes a base portion
51
b
having a hole
51
a
in the center portion thereof, a pair of arms
51
c
which extend at right angles from opposite ends of the base portion
51
b,
and supporting portions
51
d
formed on the ends of the arms
51
c.
The supporting portions
51
d
have holes formed therein by cutting away portions thereof.
Contactors
52
, formed of metallic plates, have contact portions
52
a
and terminal portions
52
b.
Similarly, a common contactor
53
, formed of a metallic plate, has a contact portion
53
a
and a terminal portion
53
b.
The contactors
52
and the common contactor
53
are disposed in a row and are embedded into and mounted to the base portion
51
b.
The contact portions
52
a
and the contact portion
53
a
are positioned within the hole
51
a.
The terminals
52
b
and the terminal
53
b
protrude outwardly from the base portion
51
b.
As best seen in
FIG. 54
, a resilient plate
54
, formed of a metallic plate, is disposed in a row with the contactors
52
and the common contactor
53
and is also mounted to the base portion
51
b.
As best seen in
FIGS. 52 and 55
, a cylindrical rotary member
55
comprises a cylindrical portion
56
molded out of synthetic resin, and a code member
57
provided at the outer circumferential surface of the cylindrical portion
56
. The code member
57
is formed of an electrically conductive material. In particular, the code member
57
is formed by molding electrically conductive resin twice.
A common pattern
57
a,
a comb-like code pattern
57
b,
and a clicking uneven portion
56
a
are formed at the outer circumferential surface of the cylindrical portion
56
so as to be disposed in a row along the direction of the rotational axis.
Shafts
56
b
are provided at both ends of the cylindrical portion
56
. A noncircular hole
56
c
is formed in the center portion of the cylindrical portion
56
.
The rotary member
55
is rotatably mounted to the insulating base
51
by snapping the shafts
56
b
into the supporting portions
51
d
of the pair of arms
51
c.
When the rotary member
55
has been mounted, the contact portion
53
a
of the common contactor
53
is in contact with the common pattern
57
a,
the contact portions
52
a
of the contactors
52
are in contact with the code pattern
57
b,
and the resilient plate
54
is in resilient contact with the uneven portion
56
a.
A dome-shaped cover
58
is mounted to the insulating base
51
so as to cover the rotary member
55
, whereby the body E
2
of the encoder is constructed.
As shown in
FIG. 53
, the body E
2
of the encoder is mounted on a printed circuit board P
2
by placing the bottom surface of the insulating base
51
on the printed board P
2
. The terminal portions
52
b
of the contactors
52
and the terminal portion
53
b
of the common contactor
53
are inserted through a hole in the printed board P
2
and are soldered onto a wiring pattern (not shown).
The conventional rotary encoder having the above-described structure operates as follows. When an actuating shaft (not shown) is inserted in the hole
56
c
of the rotary member
55
and is rotated from the outside, the rotary member
55
is likewise rotated. When the rotary member
55
is rotated, the code member
57
is also rotated. Although the common contact
53
is always in contact with the common pattern
57
a,
the contactors
52
are only in intermittent contact with the code pattern
57
b.
This causes a pulse signal to be generated between the common contactor
53
and the contactors
52
as the rotary member
55
is rotated.
The rotation of the rotary member
55
causes the resilient plate
54
to engage and disengage with the uneven portion
56
a,
thereby generating a clicking of the rotary member
55
.
However, the conventional rotary encoder is formed by molding the code member
57
out of electrically conductive resin. Consequently, the molding of the code member
57
is difficult and expensive to produce. In addition, since the common pattern
57
a,
the code pattern
57
b,
and the clicking uneven portion
56
a
are disposed in a row along the outer circumferential surface of the rotary member
55
, the conventional rotary encoder is relatively large in the direction of the rotational axis of the rotary member
55
.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a small, low-cost rotary encoder that overcomes the above-referenced problems.
To this end, according to a first aspect of the present invention, there is provided a rotary encoder comprising a rotary member which is formed of an insulating material and which has at least one of a columnar shape, a cylindrical shape, and a truncated conical shape; a code member mounted to the rotary member and formed of a metallic plate; and a plurality of contactors which contact the code member. In the rotary encoder, the code member comprises an annular plate-shaped portion and a plurality of tongues formed by bending the plate-shaped portion. The plate-shaped portion is disposed in a direction perpendicular to the direction of the rotational axis of the rotary member. The tongues are disposed so as to be exposed at a circumferential surface side of the rotary member.
Accordingly, since the code member comprising an annular plate-shaped portion and the plurality of tongues are formed of a metallic plate, it is possible to provide a low-cost rotary encoder which can be easily produced with high productivity as compared to the conventional device wherein a molded electrically conductive resin is used.
In addition, since the plate-shaped portion is disposed in a direction perpendicular to the rotational axial direction of the rotary member, and the tongues are disposed so as to be exposed at the circumferential surface side of the rotary member, a proper spacing along the rotational axis is obtained for the plate-shaped portion, thereby permiting the manufacture of a small rotary encoder.
The tongues of the code member may be formed by bending from an outer peripheral portion of the plate-shaped portion. This structure is therefore effective when the tongues need to be made long.
The tongues of the code member may alternatively be by bending from an inner peripheral portion of the plate-shaped portion. This enables material from the metallic plate to be eliminated, making it possible to provide a small, low-cost rotary encoder.
The tongues of the code member may be disposed at an outer circumferential surface side of the rotary member. Accordingly, the contactors can be freely disposed, making it possible to provide a rotary encoder adapted to various forms.
The rotary member may have a cylindrical shape, and the tongues of the code member may be disposed at an inner circumferential surface side of the rotary member. Accordingly, the code member can be made small, making it possible to provide a small rotary encoder.
When a rotary encoder comprises a rotary member, a code member, and a plurality of contactors, the code member may be embedded into the rotary member in order to be mounted to the rotary member. Accordingly, the manufacturing process can be simplified, and improved productivity is achieved, making it possible to provide a low-cost rotary encoder.
When a rotary member comprises a rotary member, a code member, and a plurality of contactors, the tongues of the code member may be fitted into a groove formed in the circumferential surface side of the rotary member in order to mount the code member to the rotary member. Accordingly, it is possible to easily adapt to various forms of the code member, so that an adaptable rotary encoder can be pr

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