Title: Multi-directional pressure-responsive input device
Abstract: The input device of the invention includes: a lower sheet on which four resistors are formed in a manner that each two of them with a center put in between are placed to face each other circumferentially with a spacing of about 90°; an upper sheet overlying the lower sheet with a spacing, on which conductors are formed to face the respective resistors; elastic bodies disposed over the upper sheet to face the respective conductors; and an operation member to retain upper parts of the elastic bodies. And, when the operation member is pressed downward, the elastic bodies are brought into contact with the resistors with interventions of the conductors on the upper sheet.
Patent Number: 6,977,644 Issued on 12/20/2005 to Endo, et al.
| Inventors:
|
Endo; Yoshihisa (Fukushima-ken, JP);
Nakai; Takashi (Fukushima-ken, JP)
|
| Assignee:
|
Alps Electric Co., Ltd. (Tokyo, JP)
|
| Appl. No.:
|
355888 |
| Filed:
|
January 31, 2003 |
Foreign Application Priority Data
| Feb 06, 2002[JP] | 2002-029536 |
| Current U.S. Class: |
345/157; 341/34; 463/37 |
| Intern'l Class: |
G09G 005/08; H03K 017/94; A63F 013/00 |
| Field of Search: |
345/156,161,157
463/37
341/34
|
References Cited [Referenced By]
U.S. Patent Documents
| 4301337 | Nov., 1981 | Eventoff.
| |
| 4433217 | Feb., 1984 | Griffith.
| |
| 5278557 | Jan., 1994 | Stokes et al.
| |
| 5396443 | Mar., 1995 | Mese et al.
| |
| 5431064 | Jul., 1995 | Franz.
| |
| 5555004 | Sep., 1996 | Ono et al.
| |
| 5815139 | Sep., 1998 | Yoshikawa et al.
| |
| 5883617 | Mar., 1999 | Yoshikawa.
| |
| 5912612 | Jun., 1999 | DeVolpi.
| |
| 5945979 | Aug., 1999 | Rutledge et al.
| |
| 6310606 | Oct., 2001 | Armstrong.
| |
| 6504492 | Jan., 2003 | Muurinen.
| |
| 6617982 | Sep., 2003 | Ogata et al.
| |
| 2001/0017592 | Aug., 2001 | Armstrong.
| |
| 2002/0000971 | Jan., 2002 | Armstrong.
| |
| 2002/0021280 | Feb., 2002 | Kato et al.
| |
| 2002/0065134 | May., 2002 | Ogata et al.
| |
| Foreign Patent Documents |
| WO 00/6454/8 | Nov., 2000 | WO.
| |
Primary Examiner: Yang; Ryan
Attorney, Agent or Firm: Brinks Hofer Gilson & Lione
Claims
1. An input device comprising:
a lower sheet on which four resistors are formed around a center, adjacent resistors
being about 90° from each other;
an upper sheet overlying the lower sheet with a spacing, on which conductors
are formed to face the respective resistors;
elastic bodies disposed over the upper sheet to face the respective conductors; and
an operation member to retain upper parts of the elastic bodies, the operation
member being movable in a downward direction or in a slant direction; and
a controller that converts an analog resistance from each of the resistors into
a digital value,
a switching section having first and second output terminals, analog voltage
input terminals, and a trigger signal input terminal, which is capable of switching
a status into one of a first mode that outputs a high level voltage only to the
first output terminal and a second mode that outputs a low level voltage to the
first output terminal and the high level voltage to the second output terminal, wherein
the switching section is configured in a manner that, in the first mode, the
status is switched into the second mode when the analog voltage input terminals
receive a voltage of a predetermined value for a specified period of time, and
in the second mode, the status is switched into the first mode when the trigger
signal input terminal receives the high level voltage;
each two facing resistors are each connected in series to each other;
a first resistor each of the two facing resistors is connected to the first output
terminal and a second resistor each of the two facing resistors is grounded;
the conductors each are connected to the second output terminal; and
nodes of the resistors on one side are connected to the analog voltage input
terminals and the trigger signal input terminal;
wherein by the operation member being pressed downward or in the slant direction,
the elastic bodies are moved downward, the upper sheet is bent, and contact areas
of the conductors and the resistances of the resistors are varied; and
wherein the controller detects a pressing direction and a pressing force of the
operation member, and includes a power-saving section that performs switching to
a power-saving stop mode when the analog resistance does not vary in a predetermined period.
2. An input device according to claim 1, wherein
each of the nodes is connected to the trigger signal input terminal through an
OR circuit; and
wherein each of the conductors is connected to the second output terminal through
a reverse-current blocking diode.
3. An input device according to claim 1, wherein
the lower sheet has plural lower contacts formed thereon;
wherein the upper sheet has upper contacts formed thereon to face each of the
lower contacts; and
wherein the lower contacts and the upper contacts that face each other are made
conductive by the operation member provided over the upper sheet being pressed.
4. An input device according to claim 3, wherein
elastic members made of a domed metal are provided over the upper sheet to face
each of the lower contacts and the upper contacts that face each other; and
wherein the elastic members are deformed by the operation member being pressed,
whereby the lower contacts and the upper contacts that face each other are made conductive.
5. An input device according to claim 1, wherein the operation member is movable
in the downward direction and is movable in a slant direction.
6. An input device according to claim 5, wherein the resistances of the resistors
decrease proportionally with increasing pressing force.
7. An input device according to claim 1, wherein the resistances of the resistors
decrease proportionally with increasing pressing force.
8. An input device comprising:
a lower sheet on which four resistors are formed around a center, adjacent resistors
being about 90° from each other;
an upper sheet overlying the lower sheet with a spacing, on which conductors
are formed to face the respective resistors;
elastic bodies disposed over the upper sheet to face the respective conductors; and
an operation member to retain upper parts of the elastic bodies,
wherein by the operation member being pressed downward, the elastic bodies are
moved downward, the upper sheet is bent, and contact areas of the conductors and
the resistors are varied,
operation of the operation member is detected,
the input device further comprises a controller having first and second output
terminals, analog voltage input terminals, and a trigger signal input terminal,
which is capable of switching a status into one of a first mode that outputs a
high level voltage only to the first output terminal and a second mode that outputs
a low level voltage to the first output terminal and the high level voltage to
the second output terminal,
the controller is configured such that, in the first mode, the status is switched
into the second mode when the analog voltage input terminals receive a voltage
of a predetermined value for a specified period of time, and in the second mode,
the status is switched into the first mode when the trigger signal input terminal
receives the high level voltage,
each two facing resistors are each connected in series to each other,
a first resistor each of the two facing resistors is connected to the first output
terminal and a second resistor each of the two facing resistors is grounded,
the conductors each are connected to the second output terminal, and
nodes of the resistors on one side are connected to the analog voltage input
terminals and the trigger signal input terminal.
9. An input device according to claim 8, wherein the operation member retains
the four elastic bodies, wherein the operation member is inclined, wherein the
elastic bodies are moved downward, wherein the upper sheet is bent, wherein the
contact areas of the conductors and the resistors are varied, and wherein a position
and strength at and by which the operation member is operated are detected.
10. An input device according to claim 8, wherein
each of the nodes is connected to the trigger signal input terminal through an
OR circuit; and
wherein each of the conductors is connected to the second output terminal through
a reverse-current blocking diode.
11. An input device according to claim 8, wherein
the lower sheet has plural lower contacts formed thereon;
wherein the upper sheet has upper contacts formed thereon to face each of the
lower contacts; and
wherein the lower contacts and the upper contacts that face each other are made
conductive by the operation member provided over the upper sheet being pressed.
12. An input device according to claim 11, wherein
elastic members made of a domed metal are provided over the upper sheet to face
each of the lower contacts and the upper contacts that face each other; and
wherein the elastic members are deformed by the operation member being pressed,
whereby the lower contacts and the upper contacts that face each other are made conductive.
Description
This application claims the benefit of priority to Japanese Application 2002-029536,
filed on Feb. 6, 2002.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an input device of a mobile electronic apparatus
such as a portable telephone, specifically to an input device capable of inputting
the direction and strength of a pressing force when a key top (operating member)
is pressed.
2. Description of the Related Art
The input device of a conventional portable telephone is made up with a printed
circuit board 81, metal contacts 83, a contact sheet 84, and
a key top 85, as shown in FIG. 9 and FIG. 10.
The printed circuit board 81 has plural pairs of fixed contacts 86
a,
86
b printed on the surface thereof, as shown in FIG. 9.
FIG. 10 illustrates the switch structure to put a pair of the fixed contacts
86
a, 86
b into a conductive state, and the other fixed
contacts have the same structure. As shown in FIG. 10, the metal contact 83
overlies the fixed contacts 86
a, 86
b mounted on the
printed circuit board 81 so as to face each other, and the contact sheet
84 is adhered on the printed circuit board 81 with the metal contact
83 put in between.
The metal contact 83 is made of a domed thin metal having a structure
capable of elastic deformation, and the circumference thereof is in contact with
the fixed contact 86
b.
And, the key top 85 overlies the contact sheet 84 vertically movably
to face the metal contact 83, and has a downward convex projection formed
to face the center of the metal contact 83.
Now, in this state, pressing the key top 85 downward deforms the metal
contact 83 to bring both the pair of fixed contacts 86
a, 86
b
into contact, whereby the pair of fixed contacts 86
a, 86
b
are made conductive, and a key input detection circuit (not illustrated) detects
that the fixed contacts 86
a, 86
b are conductive, thereby
discriminating a key input.
When a pressing load to the key top 85 is released, the key top 85
returns to the original position by the restoring force of the metal contact 83,
and the fixed contacts 86
a, 86
b are made non-conductive.
In the same manner as the fixed contacts 86
a, 86
b,
a set of fixed contacts 88, 89, 90, 91 that allow four
inputs of right, left, up, and down directions is printed on the upper front of
the printed circuit board 81, as shown in FIG. 9.
When the input operation of the corresponding direction is made by a pair of
the fixed contacts 88, 89, 90, 91 being made conductive
as mentioned above, the portable electronic apparatus shifts the cursor according
to the operated direction, and scrolls the characters and images displayed.
Recent developments have implemented some input devices detect not only the
on-off digital inputs of up, down, right, and left directions but also detect the
strength of force (analog value) during the operation.
In the input device as shown in FIG. 11, four resistors 92, 93,
94, 95 are printed on the printed circuit board 81, instead
of the fixed contacts 88, 89, 90, 91 for four directional
inputs in FIG. 9.
FIG. 12 is a sectional view that illustrates the upper structure of the resistor
92 of these resistors, and the other resistors 93, 94, 95
have the same structure as well.
As shown in FIG. 12, the resistor 92 is printed on the printed circuit
board 81, and a downward convex conductive rubber 96 is located to
overlie the resistor 92.
The conductive rubber 96 is fixed to the key top 85 by way of an
elastic body 97. The key top 85 is energized upward by an elastic
body not illustrated, and the resistor 92 faces the conductive rubber 96
with a slight spacing.
In this state, when the key top 85 is pressed down, the conductive rubber
96 is lowered, the conductive rubber 96 comes in contact with the
resistor 92, the contact area made by the conductive rubber 96 and
the resistor 92 varies according to the pressing force, and the resistance
across the resistor 92 varies.
As the pressing force to the key top 85 becomes stronger, the contact area
of the conductive rubber 96 and the resistor 92 becomes larger; and
as the contact area becomes larger, the variance (decrease) of the resistance across
the resistor 92 becomes greater. Therefore, it is possible to calculate
the force applied to the key top 85 by detecting the variance of the resistance.
When the load to the key top 85 is released, the key top 85 returns
to the original position by the restoring force of the elastic body not illustrated,
and the resistor 92 is made to face the conductive rubber 96 with
a slight spacing.
The circuit to detect the resistance of the resistor 92 is configured
with the four resistors 92, 93, 94, 95, and a controller
(CPU) 98, as shown in FIG. 13.
The controller 98 has analog voltage input terminals A/D1, A/D2
that input analog voltages, and plural input/output terminals not illustrated, etc.
One end of the resistor 92 is connected to one end of the resistor 93,
and the resistors 94 and 95 are connected in the same manner. The
other ends of the resistor 92 and 94 are connected to a power supply
Vcc, and the other ends of the resistor 93 and 95 are connected to
the ground.
The node of the resistors 92 and 93 is connected to the analog
voltage input terminal A/D1, and the node of the resistors 94 and
95 is connected to the analog voltage input terminal A/D2.
And, the controller 98 is designed to monitor the analog voltages to
be inputted to the analog voltage input terminals A/D1 and A/D2.
In the initial state that the resistors 92, 93, 94, 95
and the conductive rubber 96 face each other with a slight spacing, the
resistances of the resistors 92, 93, 94, 95 are equal,
and both the two analog voltage input terminals A/D1, A/D2 input
the voltage of Vcc/2 accordingly.
In this state, when the key top 85 is pressed to bring the conductive rubber
96 into contact with the resistor 92(X+), for example, the resistance
across the resistor 92 decreases; and accordingly, the analog voltage input
terminal A/D1 inputs a voltage higher than Vcc/2, and the analog voltage
input terminal A/D2 inputs the voltage of Vcc/2, which is not varied.
Here, since the voltage inputted to the analog voltage input terminal A/D1
has become higher than Vcc/2, the controller 98 detects that the conductive
rubber 96 comes into contact with the resistor 92(X+), calculates
the variance of the resistance of the resistor 92 from the analog voltage,
calculates the strength of the force that has pressed the key top 85 from
the variance of the resistance, and outputs the result from the output terminal
(not illustrated).
In the portable electronic apparatus, the direction of shifting the cursor and
the direction of scrolling the images are controlled from the direction thus outputted,
and the speed of shifting the cursor and the speed of scrolling are controlled
from the strength of force thus outputted.
However, in this type of input device having the fixed contacts 86
a,
86
b printed on the printed circuit board 81, there occur wear
and smear on the fixed contacts 86
a, 86
b, which lowers
the reliability and shortens the life of the contacts, thus presenting a problem
to be solved.
If the number of key switches is increased to make the input device multi-functional,
the fixed contacts 86
a, 86
b will have to be printed
on the printed circuit board 81 by the number of switches to be increased;
and since the wiring space is required for the number of switches increased, to
miniaturize the printed circuit board 81 has been an obstacle to make the
input device multi-functional.
Further, since the defects of the contact sheet 84 cannot be discovered
before the contact sheet 84 is adhered on the printed circuit board 81,
the replacement of the defective contact sheet 84 has required trouble of
peeling it off the printed circuit board 81, and so on.
Further, since the conductive rubber 96 is put into contact with
the resistor 92 to produce the variance of the resistance, and in addition
to the short life of contacts of the conductive rubber 96 itself due to
abrasion, and further since the conductive rubber 96 is directly pressed
to the resistor 92 made of carbon, for example, the life of the conductive
rubber 96 by abrasion is further shortened accordingly, which is a problem.
Furthermore, in the circuit to detect the resistances of the resistors,
since the controller 98 has to be monitoring the analog voltages inputted
to the analog voltage input terminals A/D1 and A/D2, the power consumption
increases only to shorten the continuous operational time, which is a problem.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problems, and an object
of the invention is to provide an input device that enhances the reliability and
extends the life, facilitates the setting of multi-functions and replacements if
found defective, and reduces the power consumption.
In order to solve the foregoing problems, the input device according to one aspect
of the invention includes: a lower sheet on which four resistors are formed in
a manner that each two of them with a center put in between are placed to face
each other circumferentially with a spacing of about 90°; an upper sheet overlying
the lower sheet with a spacing, on which conductors are formed to face the respective
resistors; elastic bodies disposed over the upper sheet to face the respective
conductors; and an operation member to retain upper parts of the elastic bodies.
Further, this input device is constructed in a manner that, when the operation
member is pressed downward, the elastic bodies are moved downward, the upper sheet
is bent, and contact areas of the conductors and the resistors are varied, and
thereby operation of the operation member is detected.
This construction brings the elastic bodies made of rubber or the like into
contact with the resistors on the lower sheet with interventions of the upper sheet
and the conductors, whereby the abrasion of the elastic bodies is reduced, and
the life thereof is prolonged to enhance the reliability. Further, it does not
need a conductive rubber, thus leading to lowering the production cost.
The input device is also constructed in a manner that the operation member retains
the four elastic bodies, the operation member is inclined, the elastic bodies are
moved downward, the upper sheet is bent and the contact areas of the conductors
and the resistors are varied, and thereby the position and strength at and by which
the operation member is operated are detected.
This construction allows the detection of slant directional operations as well
as the detection of up, down, right, and left directional operations, and also
the detection of the force strength when operated, which achieves a control that
a user can easily manipulate.
According to another aspect of the invention, the input device further
includes a controller having first and second output terminals, analog voltage
input terminals, and a trigger signal input terminal, which is capable of switching
a status into a first mode that outputs a high level voltage only to the first
output terminal or a second mode that outputs a low level voltage to the first
output terminal and the high level voltage to the second output terminal. And in
this construction, the controller is configured in a manner that, in the first
mode, the status is switched into the second mode when the analog voltage input
terminals receive a voltage of a predetermined value for a specified period of
time, and in the second mode, the status is switched into the first mode when the
trigger signal input terminal receives the high level voltage; the two facing resistors
are each connected in series to each other; each of the resistors on one end is
connected to the first output terminal, and each of the resistors on the other
end is grounded; the conductors each are connected to the second output terminal;
and nodes of the resistors on one side are connected to the analog voltage input
terminals and the trigger signal input terminal.
Thanks to this construction, the controller switches the status into the second
mode when the operation member is not operated for a predetermined period of time,
in which the voltage is not applied to the resistors, thus reducing the power consumption.
The input device is also constructed in a manner that each of the nodes is connected
to the trigger signal input terminal through an OR circuit, and each of the conductors
is connected to the second output terminal through a reverse-current blocking diode.
Thanks to this construction, even if, in the second mode, any of the resistors
comes in contact with the corresponding conductor, the trigger signal input terminal
will receive the high level voltage; and, even if, in the first mode, one of the
resistors comes in contact with the corresponding conductor to apply a voltage
to the conductor, it will not give any influence to the other conductors.
The input device is also constructed in a manner that the lower sheet has plural
lower contacts formed thereon, the upper sheet has upper contacts formed thereon
to face each of the lower contacts, and the lower contacts and the upper contacts
that face each other are made conductive by the operation member provided over
the upper sheet being pressed.
Thanks to this construction, the members for inputting operational directions
and the members for key inputs can be integrally formed, which contributes to reducing
the production cost. Since the members for key inputs are constructed only inside
the upper and lower films, the construction is very resistant to corrosions to
contribute to high reliability and a prolonged life of these members, and also
facilitates to discover defects.
The input device is also constructed in a manner that elastic members made of
a domed metal are provided over the upper sheet to face each of the lower contacts
and the upper contacts that face each other, and the elastic members are deformed
by the operation member being pressed, whereby the lower contacts and the upper
contacts that face each other are made conductive.
This construction gives a user a feeling of click during operation, and the
user can confirm secure operation.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an explanatory chart of the upper and lower sheet of an input device
according to the present invention;
FIG. 2 is a sectional view illustrating the construction of a key switch of
the input device according to the present invention;
FIG. 3 is a sectional view explaining the construction to vary the resistance
of a resistor of the input device according to the present invention;
FIG. 4 is a circuit diagram of a detection circuit for the resistance of the
resistor of the input device according to the invention present;
FIG. 5 is a flowchart explaining the operation of a controller of the input
device according to the present invention;
FIG. 6 is an equivalent circuit diagram in the stop mode of the circuit that
detects the resistance of the resistor of the input device according to the present invention;
FIG. 7 is an equivalent circuit diagram in the normal mode of the circuit that
detects the resistance of the resistor of the input device according to the present invention;
FIG. 8 is a chart illustrating the relation between a resistance across the
resistor and a force applied to a conductor of the input device according to the
present invention;
FIG. 9 is a chart that explains the layout and structure of fixed contacts for
switches and fixed contacts for directional inputs, which are printed on a printed
circuit board of a conventionally proposed input device;
FIG. 10 is a sectional view explaining the switch structure that makes a pair
of fixed contacts conductive of a conventionally proposed input device;
FIG. 11 is a chart that explains the layout and structure of fixed contacts
for switches and resistors for directional inputs, which are printed on a printed
circuit board of a conventionally proposed input device;
FIG. 12 is a sectional view explaining the construction to vary the resistance
of a resistor of a conventionally proposed input device; and
FIG. 13 is a circuit diagram of a detection circuit for the resistance of the
resistor of a conventionally proposed input device.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of the input device according to the invention will
be described based on FIG. 1 through FIG. 8. FIG. 1 explains the upper and lower
sheet of the input device according to the present invention, FIG. 2 illustrates
a section of a key switch of the input device according to the present invention,
FIG. 3 illustrates a section of the construction to vary the resistance of a resistor
of the input device according to the present invention, FIG. 4 illustrates a circuit
to detect the resistance of a resistor of the input device according to the present
invention, FIG. 5 is a flowchart explaining the operation of a controller of the
input device according to the present invention, FIG. 6 illustrates an equivalent
circuit in the stop mode of the circuit to detect the resistance of the resistor
of the input device according to the present invention, FIG. 7 illustrates an equivalent
circuit in the normal mode of the circuit to detect the resistance of the resistor
of the input device according to the present invention, and FIG. 8 illustrates
the relation between a resistance across the resistor and a force applied to a
conductor of the input device according to the present invention.
As shown in FIG. 1, the input device according to the invention is made up of
a lower sheet
11 and an upper sheet
12. The lower sheet
11
and upper sheet
12 are made of a sheet of film, which is folded in half
on the center when assembled.
A plurality of lower contacts
13 for key inputs are printed on the lower
sheet
11. And a plurality of upper contacts
14 each facing the lower
contacts
13 are printed on the upper sheet
12.
FIG. 2 is a sectional view illustrating the construction of a switch for the
key input.
As shown in FIG. 2, the lower sheet
11 and the upper sheet
12 are
bonded with an intervention of a spacer
24 described later.
Further, a metal contact
15 is disposed over the upper sheet
12
so as to face a pair of the lower contact
13 and the upper contact
14.
The metal contact
15 is made of a domed thin metal, and assumes a structure
capable of elastic deformation.
A key top (not illustrated) is placed vertically movably over the metal contact
15 with an intervention of a contact sheet
29 so as to face the metal
contact
15, and the key top has a downward convex projection formed to face
the center of the metal contact
15.
In this state, pressing the key top downward deforms the metal contact
15,
so that the lower contact
13 on the lower sheet
11 and the upper
contact
14 on the upper sheet
12 come in contact, whereby the lower
contact
13 and upper contact
14 are made conductive. A key input
detection circuit (not illustrated) detects the lower contact
13 and upper
contact
14 that are made conductive, and discriminates a key input.
When a load applied to the key top is released, the key top returns to the original
position by the restoring force of the metal contact
15, and the lower contact
13 and upper contact
14 are made non-conductive.
Now, when the metal contact
15 elastically deforms and recovers its original
posture, the user feels a click and confirms the key operation.
Since the switch structure of the lower contact
13 and upper contact
14 is made only inside the upper and lower sheets
11,
12,
it is very resistant to corrosions to contribute to a prolonged life, and it facilitates
to discover defects, thus enhancing the reliability.
Next, as shown in FIG. 1, four resistors
16(X+),
17(X-),
18(Y+),
19(Y-) for right, left, up, and down directional inputs, which are made
of carbon, for example, are printed on the upper side of the lower sheet
11
with a spacing of about 90° in such a manner that two of them face each other
with the center put in between. Conductors
20(X+),
21(X-),
22(Y+),
23(Y-) made of silver, for example, are printed on the upper sheet
12
so as to correspondingly face the resistors
16,
17,
18,
19
on the lower sheet
11. The conductors
20,
21 (WX) are connected
with a printed pattern, and the conductors
22,
23 (WY) are connected
with a printed pattern.
FIG. 3 is a sectional view explaining the construction to vary the resistance
of the resistor
16(X+), and the other resistors
17,
18,
19
have the same structure.
As shown in FIG. 3, the resistor
16 is printed on the lower sheet
11,
and the conductor
20 is printed on the upper sheet
12; and the spacer
24 is provided on the part except for the resistor
16 and the conductor
20.
A downward convex-formed elastic body
25 made of rubber or the like is
placed
over the upper sheet
12 so as to face the conductor
20.
The elastic body
25 with a downward convex projection is provided to face
the other resistors
17,
18,
19 as well, which is fixed to
a key top
26 for one directional input. The key top
26 for the directional
input is energized upward by an elastic body (not illustrated) for retaining the
key top
26, and in the initial state, the lower front of the elastic body
25 is in slight contact with the upper sheet
12.
When the key top
26 is pressed downward in this state, the key top
26
is inclined to lower the elastic body
25, leading to bending the upper sheet
12. Thereby, the conductor
20 and the resistor
16 come in
contact, and the contact area varies according to the pressing force, which varies
the resistance across the resistor
16.
As the pressing force is stronger, the contact area of the conductor
20
and the resistor
16 becomes larger because the lower part of the elastic
body
25 is formed in a convex; and as the contact area becomes larger, the
variance (decrease) of the resistance across the resistor
16 becomes greater.
Thereby, it becomes possible to calculate the pressing force by detecting the variance
of the resistance.
When the load to the key top is released, the key top
26 returns to the
original equilibrium by the restoring force of the elastic body for retaining the
key top
26; accordingly, the lower front of the elastic body
25 and
the upper sheet
12 return to the initial state that they are in slight contact,
and the resistor
16 recovers its original resistance.
Thus, the input device according to the invention employing the elastic body
25 made of rubber attains enhanced reliability and prolonged life.
Further, since the elastic body
25 is brought into contact with the
resistor
16 on the lower sheet
11 with an intervention of the upper
sheet
12, it is difficult to be abraded, and attains a higher reliability
and a longer life.
FIG. 4 illustrates a circuit to detect the resistances of the resistors
16,
17,
18,
19 of the input device. As shown in FIG. 4, this detection
circuit is configured with the four resistors
16,
17,
18,
19 and the four conductors
20,
21,
22,
23, and
a controller (CPU)
27.
In the drawing, the arrows attached to the conductors
20,
21,
22,
23 each signify the moving directions thereof in this circuit diagram, when
they are pressed downward.
The controller
27 is equipped with plural input output terminals such
as analog voltage input terminals A/D
1, A/D
2 that input analog voltages,
an output terminal OUT
1 (first output terminal) and an output terminal OUT
2
(second output terminal) that outputs the high level voltage or the low level voltage,
and a trigger signal input terminal IRQ that inputs a trigger signal, etc.
The controller
27 is able to switch the state into the normal mode (the
first mode) that outputs the high level voltage only to the output terminal OUT
1
or the stop mode (the second mode) that outputs the low level voltage to the output
terminal OUT
1 and outputs the high level voltage to the output terminal OUT
2.
The controller
27 is designed to switch the state into the stop mode when,
in the normal mode, a specified voltage is inputted both to the analog voltage
input terminals A/D
1 and A/D
2 for a predetermined period of time,
and to switch the state into the normal mode when, in the stop mode, the high level
voltage is inputted to the trigger signal input terminal IRQ.
Ends of the resistors
16,
17 are connected on one side to make
series connection, and the resistors
18,
19 are connected in the
same manner. The other ends of the resistor
16 and
18 are connected
to the output terminal OUT
1 of the controller
27, and the other ends
of the resistor
17 and
19 are connected to the ground.
The node of the resistors
16 and
17 is connected to the analog
voltage input terminal A/D
1, and the node of the resistors
18 and
19 is connected to the analog voltage input terminal A/D
2. Further,
the both nodes are connected to the trigger signal input terminal IRQ through an
OR circuit
28.
The conductors
20,
21 and conductors
22,
23 each
connected by a printed pattern are connected through reverse-current blocking diodes
D
1, D
2, respectively, to the output terminal OUT
2 of the controller
27.
FIG. 4 shows an example, in which an inexpensive controller
27 with comparably
few input output terminals is employed; however if there are input output terminals
to spare in the controller
27, the foregoing resistors and conductors can
be connected directly to the other input output terminals having equivalent functions
of the controller
27, without using the OR circuit
28 and the reverse-current
blocking diodes D
1, D
2, whereby the number of components can be reduced.
FIG. 5 shows the operational flow of the controller
27. In FIG. 5, when
the controller
27 is powered (step ST
51), the controller
27
outputs the low level voltage to the output terminal OUT
1, outputs the high
level voltage to the output terminal OUT
2, and thereby permits the trigger
signal input terminal IRQ to receive the trigger signal (step ST
52).
Until the trigger signal input terminal IRQ receives the trigger signal of
the high level voltage, the controller
27 stops the other operations to
make the stop mode of standby (step ST
53).
At this moment, the detection circuit is turned into the equivalent circuit illustrated
in FIG. 6. Since the conductors and the resistors are disconnected in this state,
the high level voltage from the output terminal OUT
2 is not consumed. Therefore,
this state is in the mode that hardly consumes the power.
If the key top
26 is pressed down and inclined in this state, for example,
and the conductor
20 is lowered to move to the left in FIG. 6, the conductor
20 will come in contact with the resistor
16, and the high level
voltage from the output terminal OUT
2 will be supplied to the trigger signal
input terminal IRQ by way of the resistor
16 and the OR circuit
28.
That is, the circuit illustrated in FIG. 6 becomes a circuit that detects the operation
of the key top
26 and generates the trigger signal.
And, if the trigger signal input terminal IRQ receives the high level voltage,
the controller
27 stops outputting the high level voltage from the output
terminal OUT
2, inhibits the trigger signal input terminal IRQ from receiving
the trigger signal (step ST
54), and outputs the high level voltage to the
output terminal OUT
1. Thus, the state is turned into the normal mode that
detects analog voltages being inputted to the analog voltage input terminals A/D
1,
A/D
2 (step ST
55).
At this moment, the detection circuit is turned into the equivalent circuit illustrated
in FIG. 7. In FIG. 7, when the conductor
20 comes in contact with the resistor
16 to generate a voltage on the conductor
20, the reverse-current
blocking diodes D
1, D
2 prevents the voltage from influencing the
conductors
22,
23.
While the key top
26 is not operated, the resistances of the resistors
16,
17,
18,
19 are all equal; and both the two analog
voltage input terminals A/D
1, A/D
2 are made to input a specific voltage
of Vcc/2.
However, since the conductor
20 is in contact with the resistor
16,
the resistance across the resistor
16 is decreased, and the analog voltage
input terminal A/D
1 inputs a voltage higher than Vcc/2.
Then, the controller
27 compares whether or not the voltages inputted
to the analog voltage input terminals A/D
1, A/D
2 are equal to Vcc/2
(step ST
56), and answers as not equal (N); thereby, the controller
27
detects that the resistor
16 (X+) and the conductor
20 are in contact,
and calculates the variance of the resistance of the resistor
16 from the
variance of the voltage (step ST
57).
FIG. 8 illustrates the relation between a resistance across the resistor
16
and a force applied to the conductor
20. As shown in FIG. 8, the resistance
R (Ω) across the resistor
16 draws a decreasing curve according to
magnitude of the force P applied to the conductor
20, and the variance (ΔR)
of the resistance is almost proportional to the force P applied to the conductor
20.
Accordingly, the strength of the force applied to the conductor
20
is calculated from the variance (ΔR) of the resistance, and the result is
outputted from the output terminal (not illustrated) (step ST
57).
And, for the power saving, the controller
27 turns the output terminal
OUT
1 into the low level (step ST
58), and stands by until the next
detection time, for example, for 10 milliseconds (step ST
59). When the next
detection time comes, the processing is repeated from the step ST
55.
At the step ST
56, when the voltage values inputted to the analog voltage
input terminals A/D
1, A/D
2 are both equal to Vcc/2 (Y), the controller
checks whether or not a predetermined time has passed since the voltage values
became both equal (step ST
60).
When the predetermined time has passed (Y) after they become equal, the processing
is repeated from the step ST
52, and the status is turned into the stop mode.
When the predetermined time has not passed (N) after they become equal, the
processing is repeated from the step ST
58.
In this manner, while detecting the variance of the resistance of the resistor
16, and when not detecting any variance of the resistance for the predetermined
period of time, the controller
27 switches the status into the stop mode
for the power saving to reduce the power consumption.
The method of the processing is not limited to this. It may be arranged in such
a manner that, in the normal mode, the controller
27 outputs the low level
voltage to the output terminal OUT
1 and the high level voltage to the output
terminal OUT
2 at regular intervals, monitors the trigger signal input terminal
IRQ, and switches the status into the stop mode when the trigger signal input terminal
IRQ does not receive the high level voltage.
When a slant right upper part (between the conductor
20(X+) and the conductor
21(Y+)) of the key top
26 is pressed down, the resistor
16
and the conductor
20 come in contact, and the resistor
17 and the
conductor
21 come in contact. A force Px applied to the conductor
20(X+)
and a force Py applied to the conductor
21(Y+) are calculated by the method
as mentioned above. Accordingly, the force P applied to the key top
26 is
given by the following:
Assuming that the positive direction of the X-axis (direction to the resistor
16) is 0°, and the direction of the key top
26 having been pressed
is θ (°), θ can be calculated from Py/Px=tan θ. In this
manner, even if the pressed position is in a slant direction, the pressed direction
and the strength of the pressed force can be calculated, and the controller
27
outputs the result from the output terminal (not illustrated).
The portable electronic apparatus is made to control the direction of shifting
the cursor and the direction of scrolling on the basis of the direction thus outputted,
and to control the speed of shifting the cursor and the speed of scrolling on the
basis of the strength of the force thus outputted; and a slant directional shifting
of the cursor and scrolling of the images make it easy for a user to manipulate.
As has been described, the input device according to the invention provides: a
lower sheet on which four resistors are formed in a manner that each two of them
with the center put in between are placed to face each other circumferentially
with a spacing of about 90°; an upper sheet overlying the lower sheet with
a spacing, on which conductors are formed to face the respective resistors; elastic
bodies disposed over the upper sheet to face the respective conductors; and an
operation member to retain the upper parts of the elastic bodies. Further, this
input device is constructed in a manner that, when the operation member is pressed
downward, the elastic bodies are moved downward, the upper sheet is bent, and contact
areas of the conductors and the resistors are varied, and thereby the operation
of the operation member is detected. Thus, this construction brings the elastic
bodies made of rubber or the like into contact with the resistors on the lower
sheet with interventions of the upper sheet and the conductors. Thanks to this
construction, the abrasion of the elastic bodies is reduced, and the life thereof
is prolonged to enhance the reliability. Further, since it does not need a conductive
rubber, the production cost can be reduced.
*
