Pen-shaped coordinate pointing device

Details Pen-shaped coordinate pointing device Pen-shaped coordinate pointing device

2001-09-21

2004-10-05

Shalwala, Bipin (Department: 2673)

Computer graphics processing and selective visual display system

Display peripheral interface input device

Stylus

C178S018010, C178S018070, C178S019010, C178S019030, C178S019040

Reexamination Certificate

active

06801192

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pen-shaped coordinate pointing device which indicates a position to be determined and an operation by an operator to a position detecting device, such as a tablet, for determining the position.
2. Description of the Related Art
Conventionally, a pointing device, called a “pen and tablet”, may be used as one of the input devices for computers. The pen and tablet is a combination of a platelike tablet and an input pen to be operated on the tablet by an operator. When the operator indicates an arbitrary position on the tablet with the input pen, the position is detected by the tablet and information about the position is output to a computer.
The assignee of this application has proposed various input pens and the like for pens and tablets, as disclosed in, for example, Japanese Examined Utility Model Application Publication No. 5-4034. An example of a conventional input pen will now be described with reference to FIG.
13
.
FIG. 13
is a cross-sectional view showing the general structure of an input pen
90
, as an example of a conventional input pen. Components of the input pen
90
are housed in a penholder
91
, which has almost the same shape as that of a writing instrument, such as a ballpoint pen or a fountain pen.
At the leading end of the penholder
91
, a lead
92
is disposed so as to be connected to the interior of the penholder
91
. The base end of the lead
92
is positioned in a through hole formed in a ferrite core
94
, and is fixed to a lead holder
96
. The lead holder
96
is fixed to the penholder
91
via a spring
97
.
The lead
92
has a ferrite chip
93
. In a non-operation state of the input pen
90
, approximately two-thirds of the ferrite chip
93
is positioned in the through hole of the ferrite core
94
. The lead
92
is supported by the spring
97
together with the lead holder
96
, so that it can move in the direction of expansion and contraction of the spring
97
, that is, in the axial direction of the penholder
91
, and along the through hole of the ferrite core
94
.
The ferrite core
94
is cylindrical and has a through hole extending in the longitudinal direction, in which the lead
92
is inserted. A coil
95
is wound on the outer side face of the ferrite core
94
, and is connected to a capacitor
98
in the penholder
91
so as to form a tuning circuit
99
.
The tuning circuit
99
of the input pen
90
is excited in response to radio waves of a predetermined tuning frequency, for example, a frequency fo, output from a tablet (not shown), and induced voltage is induced in the coil
95
. When the output of the waves is stopped, radio waves of a predetermined frequency are output from the coil
95
because of a current passing based on the induced voltage. The tablet receives the waves output from the tuning circuit
99
, so that the position of the input pen
90
on the tablet can be detected.
The input pen
90
operates when the leading end of the penholder
91
is pressed against the tablet. During operation, the lead
92
is pushed into the penholder
91
, and the ferrite chip
93
built in the lead
92
is moved toward the base end inside the ferrite core
94
.
Because the coil
95
is wound on the ferrite core
94
, as described, when the positional relationship among the ends of the ferrite core
94
and the ferrite chip
93
is changed, the inductance of the coil
95
is also changed. Therefore, in the tuning circuit
99
including the coil
95
, the inductance of the coil
95
is changed by the movement of the ferrite chip
93
, thereby changing the tuning frequency of the tuning circuit
99
.
In this case, when a radio signal of a frequency fo is output from the tablet, the phase of the induced voltage produced in the coil
95
shifts from that in a non-operation state due to the change in tuning frequency of the tuning circuit
99
. For this reason, the tuning circuit
99
outputs radio waves which are different in phase from the waves output from the tablet.
Accordingly, operation of the input pen
90
can be detected by exciting the tuning circuit
99
withradio waves output from the tablet and by detecting the phase difference between the waves and radio waves output from the tuning circuit
99
.
As described in the above example, the conventional pen and tablet is easy to use because there is no need to connect the tablet and the input pen, and the operational feeling thereof is similar to that of typical writing instruments, such as fountain pens and ballpoint pens.
The conventional input pen, such as the above-described input pen
90
, has a size similar to that of typical writing instruments, such as ballpoint pens, and is suited for use particularly in desktop computers and the like.
In recent years, size reduction of electronic devices has been achieved; for example, portable electronic devices, called “Personal Digital Assistants (PDA)” have become widespread. For this reason, there has also been a demand for size reduction of input devices for use in small electronic devices. It is, however, difficult to achieve a substantial size reduction without changing the constructions of the conventional input pens.
As an example, the above-described input pen
90
must not only be shortened but must also be reduced in diameter for the purpose of size reduction. Therefore, the ferrite core
94
and the lead
92
must also be reduced in diameter.
Since the lead
92
has the ferrite chip
93
therein, however, if it is reduced in diameter, the wall surface of a portion thereof with the ferrite chip
93
therein also becomes thin. Since the lead and the like are made of resin in most cases, such thinning causes insufficient strength, and the lead
92
may undergo plastic deformation due to the load applied during operation. In a case in which the lead
92
is deformed inside the ferrite core
94
, it may abut the inner wall of the ferrite core
94
and may be made unable to move. In this state, input operation with the input pen
90
is impossible. Consequently, it is difficult to reduce the diameter of the lead
92
.
On the other hand, since the ferrite core
94
has a through hole in which the lead
92
is inserted, the through hole and the peripheral wall must be reduced in diameter in order to permit the ferrite core
94
to also be reduced in diameter. In addition to the difficulty in reducing the diameter of the lead
92
, since ferrite is a fragile structural material, if the ferrite core
94
is excessively reduced, cracking may occur due to insufficient strength.
For example, in the step of winding the coil
95
on the ferrite core
94
in the production process of the input pen
90
, tension of the wire is applied to the ferrite core
94
. Furthermore, while such winding is performed in a state in which the ferrite core
94
is fixed, stress concentrates on the fixed portion of the ferrite core
94
due to the tension of the wire. Therefore, the ferrite core
94
must correspondingly have great strength. In consideration of vibrations during transportation and dropping shock tests for products, the strength which the ferrite core
94
should have is significantly great.
If the ferrite core
94
is cracked, the inductance of the coil
95
is lowered below its initial value, and the tuning frequency of the tuning circuit
99
is offset. For this reason, the input pen
90
may not work as the input device.
Therefore, the lead
92
and the ferrite core
94
in the input pen
90
must have a predetermined large strength, and it is difficult to reduce the size of the input pen
90
without changing the structure thereof.
Size reduction of electronic devices improves portability, but may decrease ease of input operation. For this reason, there has been a demand for a small input device that provides high operability.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a thinner pen-shaped coordinate pointing device which indicates a position to be determined and an operation by an operator to a positio

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