Computer keyboard key device made from a rigid printed circuit board

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention discloses a key device for a computer keyboard. More particularly, the key circuit of the computer keyboard is made from a rigid printed circuit board.

2. Description of the Prior Art

Please refer to FIG.

1

and FIG.

2

.

FIG. 1

is a schematic diagram of a known computer keyboard

10

. A sectional view along line

2

—

2

of the computer keyboard

10

is shown in FIG.

2

. The computer keyboard

10

has a plastic housing

12

and a plurality of key devices

14

fixed inside the plastic housing

12

.

The key device

14

includes two stacked flexible printed circuit board

16

, and

18

. The bottom surface

20

of the upper flexible printed circuit board

16

, and the upper surface

22

of the lower flexible printed circuit board

18

each have a conductive segment

24

and

26

respectively. A soft plastic segment

28

is installed between the two printed circuit boards

16

,

18

. A metal plate

13

is installed on the printed circuit board

16

. A supporting plate

17

is installed under the printed circuit board

18

to provide the supporting force needed for pushing the key device

14

. The soft plastic segment

28

has a hole

30

positioned between the conductive segments

24

,

26

, and the hole

30

makes a gap between the conductive segments

24

,

26

.

The key device

14

further includes a keycap

32

, a scissors-like support

34

that is moveable in up and down directions to fix the keycap

32

onto the flexible printed circuit board

32

. An elastic component

36

, installed between the keycap

32

and the flexible printed circuit board

16

, upwardly supports the keycap

32

in an elastic manner. When the keycap

32

is pushed downward, the bottom surface of the elastic component

36

will touch the conductive segment

24

of the flexible printed circuit board

16

, causing the conductive segment

24

to form an electrical connection with the conductive segment

26

of the flexible printed circuit board

18

.

Please refer to FIG.

3

.

FIG. 3

is a schematic diagram of the partial structure of another key device

40

according to the prior art for a computer keyboard

10

. The key device

40

includes two stacked flexible printed circuit boards

42

and

44

, which are adhered together. Isolation layers

54

and

56

are installed on the flexible printed circuit boards

42

and

44

, respectively. The isolation layers

54

is printed on the bottom surface

46

of the flexible printed circuit board

42

, and the isolation layer

56

is printed on the upper surface

48

of the flexible printed circuit board

44

. The isolation layers

54

,

56

encircle the conductive segments

50

and

52

, respectively. Because the isolation layer

54

protrudes from the bottom surface

46

of the flexible printed circuit board

42

, and the isolation layer

56

protrudes from the upper surface

48

of the flexible printed circuit board

44

, the thickness of the two isolation layers

54

and

56

creates a gap between the two conductive segments

50

and

52

.

Because of their flexible nature, decoders cannot be soldered onto the flexible printed circuit boards

16

,

18

and

42

,

44

. Therefore, the computer keyboard

10

can not produce decoded key signals. Instead, it must be connected to a decoding circuit (not shown) through signal lines to produce the corresponding decoded key signals. Furthermore, the supporting plate

17

is used only to provide the supporting force needed to push the key device

14

.

SUMMARY OF THE INVENTION

It is therefore an objective of the present invention to provide a key device that uses a rigid printed circuit board to solve the above-mentioned problems.

Briefly, the present invention provides a way to combine a rigid printed circuit board and a flexible printed circuit board together to form a different key device upon which can be soldered a decoder. The computer keyboard can thus produce decoded key signals without the use of an external decoding circuit.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a schematic diagram of a computer keyboard according to the prior art.

FIG. 2

is a sectional view along line

2

—

2

of the computer keyboard shown in FIG.

1

.

FIG. 3

is a schematic diagram of a partial structure of an alternative key device according to the prior art for the computer keyboard shown in FIG.

1

.

FIG. 4

is a schematic diagram according to the present invention.

FIG. 5

is a sectional view along line

5

—

5

of the computer keyboard shown in FIG.

4

.

FIG. 6

is a schematic diagram of a partial structure of an alternative key device for the computer keyboard shown in FIG.

4

.

FIG. 7

is a schematic diagram of a partial structure of a third embodiment of the key devices for the computer keyboard shown in FIG.

4

.

FIG. 8

is a schematic diagram of a partial structure of a fourth embodiment of the key devices for the computer keyboard shown in FIG.

4

.

FIG. 9

is a schematic diagram of a partial structure of a fifth embodiment of the key devices for the computer keyboard shown in FIG.

4

.

FIG. 10

is a schematic diagram of a partial structure of a sixth embodiment of the key devices for the computer keyboard shown in FIG.

4

.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Please refer to FIG.

4

and FIG.

5

.

FIG. 4

is a schematic diagram of a computer keyboard

80

according to the present invention, and

FIG. 5

is a sectional view along line

5

—

5

of the computer keyboard

80

. The computer keyboard

80

includes a plastic housing

82

, and plurality of key devices

84

fixed on the plastic housing

82

.

As the first embodiment of the present invention shown on

FIG. 5

, the key device

84

includes a keycap

90

, a rigid printed circuit board

86

, a flexible printed circuit board

88

, a soft plastic segment

106

, a metal plate

91

, and an elastic component

94

. The rigid circuit board

86

is installed inside the plastic housing

82

, and the flexible printed circuit board

88

is fixed over the rigid printed circuit board

86

. The soft plastic segment

106

is fixed between the rigid printed circuit board

86

and the flexible printed circuit board

88

. A plurality of holes

89

are formed on the flexible printed circuit board

88

. A plurality of holes

93

are formed on the soft plastic segment

106

, and each of the plurality of holes

93

is positioned right below one of the holes

89

to expose a portion of the upper surface of the rigid printed circuit board

86

. The metal plate

91

is fixed on the flexible printed circuit board

88

, and a scissors-like support

92

that is moveable in an up and down direction for fixing the keycap

90

is fixed on the metal plate

91

. The elastic component

94

for upwardly supporting the keycap

90

is installed between the keycap

90

and the flexible printed circuit board

88

. The metal plate

91

has a pinched portion

97

to support the scissors-like support

92

.

A thermal setting plastic layer

95

is installed between the metal plate

91

and the flexible printed circuit board. By applying heat, the thermal setting plastic layer

95

becomes adhesive and melted, and then the melted thermal setting plastic layer

95

will fill up the holes

89

and

93

. The thermal setting plastic layer

95

adheres together the metal plate

91

and the flexible printed circuit board

88

, and also adheres the metal plate

91

to the rigid printed circuit board

86

through the holes

89

and

93

.

There are other choices for installing the thermal setting plastic layer

95

, it may be installed between the flexible printed circuit board

88

and the soft plastic segment

106

, or between the soft plastic segment

106

and the rigid printed circuit board

86

. In these cases, the thermal setting plastic layer

95

still can adhere together different devices of each layer by filling up the holes

89

and

93

.

Additionally, the thermal setting plastic layer

95

may be installed between the two printed circuit board

88

and

86

to replace the soft plastic segment

106

. In this case, there is no hole formed on the thermal setting plastic layer

95

under the holes

89

of the flexible printed circuit board

88

. The thermal setting plastic layer

95

thus adheres the two printed circuit board

88

and

86

together, and simultaneously adheres the metal plate

91

to the flexible printed circuit board

88

through the holes

89

of the flexible printed circuit board

88

.

The upper surface

96

of the rigid printed circuit board

86

has two adjacent but unconnected conductive ends

98

, and two wires

100

electrically connected with the two conductive ends

98

respectively. The bottom surface

102

of the flexible printed circuit board

88

has a conductive segment

104

extended over the two conductive ends

98

of the rigid printed circuit board

86

. The soft plastic segment

106

has a hole

108

formed between the conductive segment

104

and the two conductive ends

98

, and the thickness of the soft plastic segment

106

defines a gap between the conductive segment

104

and the two conductive ends

98

.

When the thermal setting plastic layer

95

is installed between the two printed circuit boards

86

,

88

, the thermal setting plastic layer

95

will have a hole formed at the position corresponding to the hole

108

of the soft plastic segment

106

to allow the two conductive ends

98

can selectively contact with the conductive segment

104

.

When the keycap is pushed downward, the bottom of the elastic component

94

will touch the conductive segment

104

of the flexible printed circuit board

88

, bringing the conductive segment

104

into contact with the two conductive ends

98

of the rigid printed circuit board

86

, and thus electrically connecting together the two conductive ends

98

.

The required electrical components of the computer keyboard

80

can be selectively fixed onto the upper or the bottom surface of the rigid printed circuit board

86

. For example, a decoder

110

can be soldered on the bottom surface, and the two wires

100

and conductive ends

98

are then electrically connected to the decoder

110

. When the decoder

110

detects that the two conductive ends

98

are electrically conducted to each other, the decoder

110

will produce a corresponding key signal.

Please refer to the second embodiment shown on FIG.

6

.

FIG. 6

is a schematic diagram of the partial structure of an alternative key device

120

for the computer keyboard

80

. The key device

120

includes a rigid printed circuit board

122

and a flexible printed circuit board

124

fixed over the rigid printed circuit board

122

. A dielectric layer

128

, known as the isolation layer, is printed on the bottom surface

126

of the flexible printed circuit board

124

. This dielectric layer

128

encircles a conductive segment

130

, and it defines a gap between the conductive segment

130

and two conductive ends

132

. By applying heat, a thermal setting plastic layer (not shown) disposed between circuit boards

124

and

122

becomes melted and adhesive for bonding the circuit boards

124

and

122

together.

A decoder

134

electrically connected to the two wires

136

and the conductive ends

132

is fixed on the upper or the bottom surface of the rigid printed circuit board

122

. When the decoder

134

detects that the two conductive ends

132

are electrically conducted to each other (via the conductive segment

130

), the decoder

134

will produce a corresponding key signal.

As the two embodiments shown above, because the conductive segments

104

,

130

on the bottom surfaces

102

,

126

of the flexible printed circuit boards

88

,

124

occupy very small area, the volume of the elastic component

94

can be reduced. The volume of the key devices

84

,

120

can thus be reduced, and it will make the keyboard

80

more compact. The rigid printed circuit boards

86

,

122

have a strong structure that can withstand the downward force needed to depress the key

90

, as well as accommodating other required electrical components, such as the decoders

110

and

134

. These decoders can be soldered onto the rigid printed circuit boards

86

,

122

to produce decoded key signals.

Please refer to FIG.

7

.

FIG. 7

is a schematic diagram of the partial structure of the third embodiment of the present invention, a key device

140

for the computer keyboard

80

. The key device

140

includes a metal plate

151

, a rigid printed circuit board

142

fixed under the metal pate

151

, and a flexible printed circuit board

144

fixed between the metal plate

151

and the rigid printed circuit board

142

. A first conductive end

148

is formed on the upper surface

146

of the rigid printed circuit board

142

, and a second conductive contact

152

is formed on the bottom surface

150

of the flexible printed circuit board

144

and right above the first conductive end

148

. A dielectric layer

154

, known as an isolation layer, is printed on the bottom surface

150

of the flexible printed circuit board

144

, which encircles the second conductive end

152

. The dielectric layer

154

protrudes from the bottom surface

150

of the flexible printed circuit board

144

to form a gap between the two conductive ends

148

,

152

.

A thermal setting plastic layer

143

is installed between the metal plate

151

and the flexible printed circuit board

144

. The flexible printed circuit board

144

has a plurality of holes

173

to expose a portion of the upper surface of the rigid printed circuit board

142

. When the thermal setting plastic layer

143

is melted by heat, not only will the metal plate

151

adhere to the flexible printed circuit board

144

, but the thermal setting plastic layer

143

will also adhere the rigid printed circuit board

142

to the flexible printed circuit board

144

through the holes

173

.

The rigid printed circuit board

142

has at least one wire

158

electrically connected to the first conductive end

148

, and the flexible printed circuit board

144

also has at least one wire

156

electrically connected to the second conductive end

152

. A decoder

160

is soldered on the rigid printed circuit board

142

, which is electrically connected to the two conductive ends

148

,

152

and the two wires

158

,

156

. When the decoder

160

detects that the two conductive ends

148

,

152

are electrically conducted together, the decoder

160

will produce a corresponding key signal.

Please refer to FIG.

8

.

FIG. 8

is a schematic diagram of the partial structure of the fourth embodiment of the present invention, a key device

170

for the computer keyboard

80

. The difference between the key device

170

and

140

is the inclusion of a soft plastic segment

172

between the bottom surface

150

of the flexible printed circuit board

144

and the upper surface

146

of the rigid printed circuit board

142

to replace the dielectric layer

154

shown in FIG.

7

.

The soft plastic segment

172

has a plurality of holes

175

, and a hole

174

under the second conductive end

152

to form a gap between the second conductive end

152

and the first conductive end

148

. The flexible printed circuit board

144

also has a plurality of holes

173

that correspond to the holes

175

of the soft plastic segment

172

. When the thermal setting plastic layer

143

is melted by heat, not only will the metal plate

151

adhere to the flexible printed circuit board

144

, but the thermal setting plastic layer

143

will adhere the rigid printed circuit board

142

under the metal plate

151

to the soft plastic segment

172

through the holes

173

and

175

.

The thermal setting plastic layer can also be installed between the flexible printed circuit board

144

and the soft plastic segment

172

, or between the soft plastic segment

172

and the rigid printed circuit board

142

. The thermal setting plastic layer will adhere together different devices of all the layers through the holes

173

and

175

. If the thermal setting plastic layer

143

is of a sufficient thickness, it can replace the soft plastic segment

172

to form the gap between the two printed circuit boards

142

and

144

.

Please refer to FIG.

9

.

FIG. 9

is a schematic diagram of the partial structure of a fifth embodiment of the present invention, a key device

180

for the computer keyboard

80

. The key device

180

includes a keycap

183

, a rigid printed circuit board

182

under the keycap

183

, a metal plate

191

fixed over the rigid printed circuit board

182

, a scissors-like support

185

to moveably fix the keycap

183

on the rigid printed circuit board

182

in an up and down manner, and an elastic component

181

installed between the keycap

183

and the rigid printed circuit board

182

to upwardly and elastically support the keycap

183

. A thermal setting plastic layer

193

between the metal plate

191

and the rigid printed circuit board

182

adheres the metal plate

191

to the rigid printed circuit board

182

. A plurality of pinched portions

195

on the metal plate

191

are used to support the scissors-like support

185

.

The upper surface

184

of the rigid printed circuit board

182

has two adjacent but unconnected conductive ends

186

, and two wires

188

electrically connected to the two conductive ends

186

, respectively. The inside surface

194

of the elastic component

181

has a conductive segment

190

above the two wires ends

186

.

The rigid printed circuit board

182

also has a decoder

196

that is electrically connected to the two conductive ends

186

. When the elastic component

181

is pushed downward, the conductive segment

190

will touch the two conductive ends

186

, electrically connecting them together. When the decoder

196

senses that the two conductive ends

186

are electrically connected to each other (via the conductive segment

190

), the decoder

196

will produce a corresponding signal.

Please refer to FIG.

10

.

FIG. 10

is a schematic diagram of the partial structure of a sixth embodiment of the present invention, a key device

200

for the computer keyboard

80

. The difference between the key device

200

and

180

is that the key device

200

does not have the metal plate

191

. Instead, it has a plurality of predetermined holes

202

on the rigid printed circuit board

182

to fix the pinched portion

195

onto the rigid printed circuit board

182

that is used to support the scissors-like support

185

. The pinched portion

195

may be directly soldered or screwed onto the rigid printed circuit board

182

. The method may also be used in the embodiments that have a flexible printed circuit board.

In contrast to the prior art computer keyboard

10

, the key devices

84

,

120

,

140

,

170

,

180

, and

200

for the computer keyboard

80

according to the present invention include the rigid printed circuit boards

86

,

122

,

142

, and

182

. Because of the rigidity of the rigid printed circuit board, there is no need for any supporting plates. Electrical components that may be required can also be installed on the rigid printed circuit board, such as the decoders

110

,

134

,

160

, and

196

. The keyboard

80

can thus provide decoded key signals.

Those skilled in the art will readily observe that numerous modifications and alternations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.