Position control device

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a position control device, more particularly to one suitable for controlling movement of a pointer or cursor.

2. Description of the Related Art

Many types of cursor control devices, such as joysticks, computer mice and digitizing boards, are available in the market. Since conventional joysticks employ at least four microswitches to detect the desired direction of movement, it difficult to further reduce the size of the joystick for application on a computer keyboard.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide a position control device having a simple construction and a relatively small size.

According to the present invention, a position control device comprises a base board, a conductive spring contact unit and a control key. The base board has one side provided with a conductive contact set that includes a plurality of angularly spaced conductive contacts. The conductive spring contact unit is secured to the base board, and includes a plurality of angularly spaced spring contact arms that extend in radial directions and in a direction away from the base board such that each of the spring contact arms overlies spacedly a corresponding one of the conductive contacts of the conductive contact set. The control key is disposed on the conductive spring contact unit such that application of a force on the control key in a direction toward the base board will result in movement of an appropriate one of the spring contact arms for establishing electrical connection with the corresponding one of the conductive contacts.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:

FIG. 1

is an exploded view illustrating the first preferred embodiment of a position control device according to the present invention;

FIG. 2

is a sectional view showing the first preferred embodiment in a non-operated state;

FIG. 3

is a schematic top view of the first preferred embodiment, with a control key thereof illustrated in phantom lines;

FIG. 4

is a sectional view showing the first preferred embodiment in a first operative position;

FIG. 5

is a sectional view showing the first preferred embodiment in a second operative position;

FIG. 6

is a sectional view illustrating the second preferred embodiment of a position control device according to the present invention;

FIG. 7

is an exploded view illustrating the third preferred embodiment of a position control device according to the present invention; and

FIG. 8

is a sectional view showing the third preferred embodiment in a non-operated state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure.

Referring to

FIGS. 1

to

3

, the first preferred embodiment of a position control device according to the present invention is shown to comprise a base board

1

, a conductive spring contact unit

2

, and a control key

3

.

The base board

1

, such as a printed circuit board or a thin film circuit board, is formed with a first through hole

10

. A conductive ring member

11

is mounted in a periphery of the base board

1

that confines the first through hole

10

. In this embodiment, three conductive contact sets are provided on a top side of the base board

1

, each of which includes eight angularly spaced conductive contacts

12

disposed at different angular positions with respect to the first through hole

10

. The conductive contact sets are located at different radial distances with respect to the first through hole

10

. The conductive ring member

11

and the conductive contacts

12

are connected electrically to a control circuit (not shown) via circuit traces (not shown) on the base board

1

in order to provide the conductive ring member

11

and the conductive contacts

12

with different electrical characteristics. Since the feature of the present invention is not directed to the construction of the control circuit, which can be easily achieved by the person skilled in the art, a detailed description of the same will be omitted herein for the sake of brevity.

In the preferred embodiment, the conductive spring contact unit

2

is formed integrally from a metal spring plate, and includes a central portion

20

and eight angularly spaced spring contact arms

21

that radiate from the central portion

20

and that curve upwardly in a direction away from the base board

1

. The spring contact arms

21

thus cooperate to form a bowl-shaped configuration. Each of the spring contact arms

21

overlies spacedly a corresponding one of the conductive contacts

12

in each of the conductive contact sets. Each of the spring contact arms

21

is formed with three contact projections

22

, each of which corresponds to said one of the conductive contacts

12

in a respective one of the conductive contact sets. The central portion

20

is formed with a second through hole

23

that is aligned with the first through hole

10

. The conductive spring contact unit

2

is secured on the top side of the base board

1

, with the conductive spring contact unit

2

in electrical contact with the conductive ring member

11

such that the conductive spring contact unit

2

has the same electrical characteristic as the conductive ring member

11

. In this embodiment, a rivet

4

is formed with a third through hole

40

coaxial with the through holes

10

,

23

, and is mounted in the first and second through holes

10

,

23

, thereby securing the conductive spring contact unit

2

on the base board

1

.

The control key

3

has a top operating side

30

and a conic bottom base side

32

such that a cross-section of the control key

3

decreases gradually in the direction toward the base board

1

. The control key

3

has a peripheral portion

36

formed with a stop flange

31

that extends in the direction toward the base board

1

. The control key

3

further has a mounting post

33

that extends from a central part of the base side

32

in the direction toward the base board

1

. The control key

3

is disposed on the conductive spring contact unit

2

such that the mounting post

33

extends through the third through hole

40

in the rivet

4

, and such that the spring contact arms

21

bear against the base side

32

of the control key

3

. Since only distal ends of the spring contact arms

21

bear against the base side

32

, the remaining parts of the spring contact arms

21

form spaces

37

with the base side

32

. The spring contact arms

21

are initially in a slightly compressed state by virtue of the weight of the control key

3

. The distal ends of the spring contact arms

21

further form clearances

35

with the stop flange

31

in the radial directions. Due to the clearances

35

, deformation of the spring contact arms

21

is possible and can be limited by the stop flange

31

. The mounting post

33

has a cross-section smaller than the size of the third through hole

40

to permit pivoting movement of the mounting post

33

relative to the base board

1

. A retainer

5

engages one end of the mounting post

33

that extends through the rivet

4

for retaining pivotally the control key

3

on the base board

1

. In this embodiment, the retainer

5

is hemispherical in shape, and has a convex surface

50

that abuts against the rivet

4

and that extends into the third through hole

40

. The convex surface

50

aids pivoting movement of the mounting post

33

and proper positioning of the control key

3

. An optional operating stick

34

, which is aligned with the mounting post

33

, may be mounted on the operating side

30

of the control key

3

to facilitate pivoting control of the latter.

Referring to

FIGS. 2

to

5

, when a force is applied on the control key

3

in the direction toward the base board

1

, the control key

3

will force the conductive spring contact unit

2

to elastically deform. Depending on the amount of the applied force, at least one of the contact projections

22

on the spring contact arm

21

pressed by the control key

3

will be brought into contact with the corresponding conductive contact

12

on the base board

1

, thereby permitting control of cursor direction and moving speed. Particularly, when the control key

3

is pressed lightly so as to pivot relative to the base board

1

in the direction indicated by the arrow in

FIG. 4

, an appropriate one of the spring contact arms

21

will be moved toward the base board

1

. A first contact projection

22

on the appropriate spring contact arm

21

will be brought into contact with the corresponding conductive contact

12

of the first conductive contact set closest to the conductive ring member

11

, thereby establishing electrical connection between the conductive contact

12

and the conductive ring member

11

. The control circuit (not shown) is thus informed of the desired direction of cursor movement. As shown in

FIG. 5

, when a greater amount of force is applied on the control key

3

, the second and third contact projections

22

on the appropriate spring contact arm

21

will eventually be brought into contact with the corresponding conductive contacts

12

of the second and third conductive contact sets, thereby informing the control circuit (not shown) of the desire to move the cursor at faster speeds. Once the control key

3

is released, the restoring force of the spring contact arms

21

will restore the control key

3

to the initial non-operated state shown in FIG.

2

.

Because the conductive spring contact unit

2

is provided with eight spring contact arms

21

, position control in at least eight directions is possible in the position control device of

FIGS. 1

to

5

. That is to say, if two adjacent spring contact arms

21

are simultaneously pressed by the control key

3

for contacting the conductive contacts

12

, the direction of movement will be in the direction between the adjacent spring contact arms

21

. Thus, direction and speed control is possible in sixteen directions in the position control device of

FIGS. 1

to

5

. The number of spring contact arms

21

and the number of conductive contacts

12

can be varied to vary the sensitivity of the position control device.

FIG. 6

illustrates the second preferred embodiment of a position control device according to the present invention. Unlike the previous embodiment, a biasing member

6

, in the form of a coil spring, is sleeved on the mounting post

33

and bears against the base side

32

of the control key

3

and the rivet

4

, thereby biasing the control key

3

away from the base board

1

. The biasing member

6

facilitates restoring of the control key

3

to the initial non-operated state.

FIGS. 7 and 8

show the third preferred embodiment of a position control device according to the present invention. Unlike the previous embodiments, no mounting post is provided for retaining the control key

3

′ on the base board

1

. Instead of a mounting post, a hollow positioning cover

7

is in use. The positioning cover

7

includes an annular bottom flange

70

mounted on the base board

1

and surrounding the conductive contact sets, an upright outer peripheral wall

71

extending upwardly from the bottom flange

70

and beyond the operating side

30

of the control key

3

′ an annular upper flange

72

extending radially and inwardly from a distal end of the outer peripheral wall

71

and overlapping the peripheral portion

36

of the control key

3

′, and an upright inner peripheral wall

73

extending downwardly from the upper flange

72

for restricting the movement of the control key

3

′ in the direction away from the base board

1

. The inner peripheral wall

73

confines an opening

74

for access to the operating side

30

of the control key

3

′. The base side

32

of the control key

3

′ is formed with a central recess

38

. A spiral coil spring

39

is in the form of a series of concentric turns of increasing diameter. The coil spring

39

has a wider end that extends into the central recess

38

and that bears against the control key

3

′. Unlike the previous embodiments, the rivet

4

′ is a solid body having a recessed top side

41

. The coil spring

39

further has a narrow end that is seated on the recessed top side

41

of the rivet

4

′. The operation of the third preferred embodiment is essentially the same as that of the previous embodiments and will not be detailed further.

While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.