Pen coordinate reading device with pen attribute detecting...

Details Pen coordinate reading device with pen attribute detecting... Pen coordinate reading device with pen attribute detecting...

2000-08-10

2004-06-01

Chow, Dennis-Doon (Department: 2675)

Computer graphics processing and selective visual display system

Display peripheral interface input device

Stylus

C345S174000, C178S018070

Reexamination Certificate

active

06744426

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coordinate reading device and a coordinate input device.
2. Description of the Related Art
Various types of coordinate reading device and a coordinate input device have been proposed.
SUMMARY OF THE INVENTION
FIG.
1
(
a
) is a configuration of a conceivable coordinate reading device and a conceivable coordinate input device. The conceivable coordinate reading device includes: a table
91
, a scanning circuit
92
, and a detection circuit
90
. The tablet
91
is provided with a plurality of X sense coils (conductive loop wires) X
1
to Xm and Y sense coils (conductive loop wires) Y
1
to Yn. The X sense coils X
1
to Xm are for detecting X coordinates of a pen (coordinate input device)
400
, the Y sense coils Y
1
to Yn are for detecting Y coordinates of the pen
400
. The scan circuit
90
is for serially scanning the sense coils X
1
-Xm and Y
1
-Yn on the tablet
91
. The detection circuit
90
is for calculating the x and y coordinates of the pen by detecting induction signals generated at the sense coils X
1
-Xm and Y
1
-Yn.
The pen (coordinate input device)
400
includes a coil
401
that generates an alternating magnetic field. When the pen
400
contacts the tablet
91
, some sense coils that are located near to the pen
400
generate induction signals
97
due to magnetic coupling with the alternating magnetic field from the coil
401
. The induction signals
97
are inputted into the detection circuit
90
. The induction signal
97
are amplified at an amplifier
93
and then its amplitude is detected at an amplitude detection circuit
94
. Next, and A/D conversion circuit
95
converts the measured amplitude into digital values, and outputs the digital values to a CPU
96
. The CPU
96
calculates the positional coordinate of the pen
400
based on the inputted digital values from the A/D conversion circuit
95
. For example, the CPU
96
may refer to a coordinate table that stores data indicative of a relationship between a plurality of digital values and coordinate positions. The CPU
96
selects a positional coordinate that corresponds to the digital values presently inputted from the A/D conversion circuit
95
.
Japanese Patent-Application Publication (Kokai) No. HEI-5-233127 discloses a coordinate reading device for a plurality of different type pens. Each pen transmits a code train that includes attribute information indicating attributes of the pen. The coordinate reading device detects the attribute information in the signal.
FIG.
1
(
b
) is a timing chart showing an example of the code train transmitted from the pen. The code train G includes ten bits; two start bits, seven bits indicating pen attribute information, and a single stop bit. The code train G is superimposed on an alternating magnetic field from the pen in accordance with an operation clock F and then outputted.
In the coordinate reading device, the sense coils generate signals to response to the alternating magnetic field transmitted from the pen. The coordinate reading device reads the code train G that is superimposed in the generated signals, and detects the pen attribute information.
According to this method proposed by the publication, however, the coordinate reading device cannot recognize the pen attribute information unless it receives the code train G over a plurality of periods from the start bit to the stop bit.
Also, the coordinate reading device can not recognize the pen attribute information unless the operation clock of the pen is synchronized with the operation clock of the coordinate reading device.
Further, if detection by the sense coils is started somewhere between the start bit and the stop bit, then the coordinate reading device has to wait until the next start bit, and receive the entire code train from the start bit to the stop bit, or will not be able to detect pen attribute information. Thus, it takes a great deal of time to determine the pen attribute information.
Japanese Patent-Application Publication (Kokai) No. HEI-7-160400 discloses another coordinate reading device and a pen (coordinate input device). According to this publication, the pen generates an alternating magnetic field, whose frequency changes according to color of ink in the pen. The pen includes a switch that enables changing the frequency of the alternating magnetic field in accordance with the ink color. The coordinate reading device recognizes the color of the ink by detecting frequency of the alternating magnetic filed outputted from the pen.
In the configuration proposed by this publication, however, the coordinate input device (pen) switches frequency in accordance with the ink color. The coordinate reading device detects the ink color according to the received frequency. It is impossible for the pen to transmit values that consecutively change, such as pressure, at which the pen is pressed against the writing surface of the coordinate reading device. Also, because only a certain number of frequency bands can be used, this configuration can use frequency to designate only a limited number of attributes, that is, the ink color.
Japanese Patent-Application Publication (Kokai) No. HEI-5-274079 discloses a coordinate input device (pen) which includes a marker portion and a case portion. The marker portion is detachably attached to the case portion, and includes a coil and an ink tank filled with ink. The marker portion is used to draw character and figures on a white board using the ink in the ink tank. The case portion includes a battery and a signal tuning circuitry for producing signals to cause the white board to detect the position of the pen. When the ink in the marker portion runs out, then the marker portion is detached from the case portion and is discarded. A new marker portion filled with ink is then attached to the case portion in its place. With this configuration, the battery and the circuitry in the case portion can still be used, so running costs are low. However, the only information the white board obtains from the tuning unit is the position of the input unit on the board.
In view of the above-described drawbacks, it is an objective of the present invention to provide an improved coordinate input device which is capable of transmitting information so that the coordinate reading device can distinguish the information in a short period of time, and to provide an improved coordinate reading device which is capable of distinguishing information, transmitted from a coordinate input device, in a short period of time.
It is another objective of the present invention to provide an improved method for communicating information so that an information receiving side can distinguish the information in a short period of time.
It is another object of the present invention is to provide an improved coordinate input device which is capable of transmitting information indicating a variety of attributes and consecutively-changing values, and an improved coordinate reading device which is capable of detecting information indicating a variety of attributes and consecutively-changing values.
It is still another objective of the present invention to provide an improved coordinate input device wherein a single case portion can be used with a plurality of different marker portions with different colors, wherein the marker portions can be exchanged simply and easily, wherein the characters drawn on the board will properly match ink color information transmitted to the coordinate reading device.
In order to attain the above and other objects, the present invention provides a coordinate reading system, comprising: a coordinate input device, the coordinate input device including: a coil generating an alternating magnetic field; an angle-modulation portion that modulates the alternating magnetic field in an angle modulation to thereby successively change an angle state of the alternating magnetic field into a plurality of different states in a plurality of successive time durations, with a length of at least one tim

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