JPS61107422A - Table input device - Google Patents

Abstract

PURPOSE:To reduce the number of times of required scanning of electrode lines, to attain high speed, simplicity in structure and more cost reduction by specifying a coordinate to be commanded depending on the quantity of a charging current of the group electrode line. CONSTITUTION:A CPU applies an address signal AD to a driver DX1 via a multiplexer MPX1. The driver DX1 applies a sequential scanning pulse to the group electrode line according to the address AD. A charging current flows to each group electrode line, a signal SS according to the quantity is generated across a resistor RS and stored in a prescribed number of a RAM via an amplifier AMP, an AD converter and an IO. The CPU activates sequentially drivers DS2, DY1, DY2 to store the signal to a prescribed address of a RAM. The CPU discriminates the contact positionof an input pen 12 based on a digital value of the detection signal SS.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tablet input device, and more particularly to improvements in the electrode wire arrangement and coordinate identification method in a capacitively coupled tablet input device.

[Conventional technology]

Improving functionality and reducing costs are universal themes in product development. In the case of capacitively coupled tablet input devices, one such theme is improving coordinate detection speed and reducing assembly man-hours and the number of parts per unit.

[Problem that the invention seeks to solve]

However, it is difficult to solve these two issues simultaneously. For example, patent application No. 21 filed in 1982 by the applicant
No. 4,501 and Patent Application No. 113,442 of 1981, in order to shorten the scanning time, digit electrode lines for block specification are further arranged between one electrode line for normal coordinate specification.

However, with this method, if the required segment spacing is 6 m, then 1 normal electrode wire is 6 Kl &
After all, you will have to place them at intervals and then place electric beams between them.

The interval between the electrode wires is 3 m, which is half the interval between the segments. As a result, one interval is a lot of chivalry.

Increased man-hours for pattern creation and increased difficulty in processing.

This results in the need to change the electrode line pattern in order to cope with the decrease in the signal output of the lower electrode due to the increased curling effect of the upper electrode, resulting in an increase in cost.

[Means for solving problems]

Therefore, in the present invention, the first and second electrode wires are arranged alternately in 1,000 rows, and the first electrode wires are connected in parallel every m and the second electrode wires are connected in parallel every m + n to form a group electrode. A scanning pulse is applied to the group electrode wires, and the designated coordinates at that time are specified based on the difference in the magnitude of the charge flowing through the group electrode wires.

[For production]

That is, when different numbers of first electrode wires and second electrode wires are connected in parallel in this way, 1, for example, m=7. n=-1
Then, while the 1st, 8th, 15th, ... peaks, etc. of the first electrode line belong to the same electrode ffl, fM group, the second electrode line next to them belongs to the same electrode ffl, fM group. 1'4i of electrode wire
The 8th, 15th, etc. belong to different electrode wire groups, for example, the 8th is the 2nd, the 15th is the 5th, and so on. .

Therefore, if each electrode wire group is scanned and the number of the first electrode wire group closest to the contact position is determined from the timing of the detection pulse at that time, the contact position will be determined from the combination of It becomes possible to judge whether the position is between the electrode line and the second electrode line.

Also, according to the inventor's research, in capacitively coupled tablets,
When you specify the desired coordinates with an input pen or fingertip with the tip of the detection rod grounded, the ground capacitance of the electrode wire passing near the specified coordinates becomes higher than that of other electrode wires, and when scanning There is a characteristic that the charging current flowing through these electrode wires is larger than the charging current flowing through other electrode wires.

Therefore, in the present invention, by adopting the former type of electrode line connection, the required number of electrode line scans can be reduced and high speed can be achieved without increasing the cost, and at the same time, the latter type of detection method can be adopted. Therefore, the structure of the input pen can be simplified, thereby further reducing the cost.

〔Example〕

The details of the present invention will be explained below based on illustrated embodiments. 1st
The figure shows an example of the electrode line arrangement in the X direction. In the figure, 1
1 indicates the first electrode line, and 2 indicates the second electrode line.To distinguish them, suffixes A to Lt are added to them in order from the left. (The electrode wire 2ZIC will be described later.) In this embodiment, the first electrode wires 1 are connected in parallel every five from the left to form a group electrode wire 3.4.
, 5.6, and the second electrode wires 2 are connected every second from the left to form a group electrode) 97,8°9.

FIG. 2 shows an example of the block configuration. In the figure, 11 is a tablet board, and the electrode wire group 3 in the X direction shown in FIG.
In addition to electrode lines 21 to 9, similar electrode wire groups 21 to 27 are also arranged in the Y direction. 12 is an input pen, the detection tip 15 of which is grounded. 14 is a pen switch built into the input pen.

DXl is a driver that supplies scanning pulses to the group electrode lines 5 to 6 of the first electrode line 1 in the X direction in accordance with an address signal supplied from a central processing unit CPU to be described later. DX2. D.Y.
l, DY2 are also drivers, and like DXl, each group electrode line
Scanning pulses are supplied at 7-9 degrees 1-24, and 25-27 degrees, respectively. A power supply voltage VCC is supplied to each power input terminal PT of these drivers via a detection resistor R8, and when the scanning pulse is applied, each group electrode line 3 to 9, 21 to
A detection signal SS is generated across this resistor R8 due to the charging current of 271CrN.

AMP is an amplifier that amplifies the detection signal SS. A/
D is an analog-to-digital converter that converts the analog value of the amplified detection signal into a digital value. M P X is a multiplexer for each driver DX1. DX2. DYE, DYE
The address signal is switched and supplied to 2.

The central processing unit (CPU) is composed of, for example, an Intel Corporation Z80, and executes predetermined processing using a random access memory RAM according to a program written in a read-only memory ROM. IO is an input/output port through which data is exchanged between the central processing unit CPU and external circuits. Note that in the following explanation, the name of each block will be omitted.

Details of the driver DX1 are shown in FIG. 3. In the figure 101
is a decoder that decodes the address signal AD supplied from the CPU via the terminal ADT and the multiplexer MPX. T5 to T7 are field effect transistors, each with a gate.

The respective sources are connected to the corresponding output terminals D3 to D6 of the decoder 101, the respective sources are connected to the corresponding X group electrode lines 5 to 6, and the seven drains are connected to the resistor R8 via the terminal FT. R3-R7 are discharge resistors connected between each source and ground.

In addition, driver DX2. The structures of DY and DY2 are also similar to this driver DX1.

Then, when the input pen 12 comes into contact with the tablet 11,
The pen switch 14 operates and the signal PSW is supplied to the CPU via IO. In response to the arrival of this signal PSW, the CPU supplies a switching signal OH to MPX, and first sets the connection destination to DXl. Then the CPU
For DXl via X, its value becomes 0 at regular time intervals.
An address signal AD that changes sequentially from 3 to 3 is supplied.

DXl sequentially supplies scanning pulses SP3 to SP6 to group electrode lines 5 to 6 in accordance with this address signal AD as described above. By applying these scanning pulses SP5 to SP6, a charging current flows through each group electrode line 3 to 6, and a signal S corresponding to the magnitude of the charging current flows through each group electrode line 3 to 6.
S is generated in the resistor I'LS, and this is supplied to the AMP. The vertical axis shows the pulse height H1, the horizontal axis shows the time t, and No. 4 S83 to S
S6 applies scanning pulses SP5 to S to group electrode lines 5 to 6, respectively.
This is the signal SS detected when P6 is applied. This signal SS is then amplified by the AMP and converted into a digital value according to each pulse height H by the AD.

The CPU uses this digital value supplied via IO as RA
Store it at a predetermined location in M. The next 1CCPU switches MPX and supplies address signal AD to DX2. DX
2 applies scanning pulses SP7 to SP9 to each group electrode line 7 to 9 in accordance with this address signal AD, as described above,
A signal SS is generated at resistor R8. Detection signal S at this time
An example of S is shown in FIG. In this figure, signals SS7 to S
S9 indicates a signal SS when a scanning pulse is applied to group electrode lines 7 to 9, respectively.

These signals SS7 to SS9 are also digitally converted and stored at a predetermined location in the RAM.

Thereafter, in the same manner, the 1st column in the Y direction. Second, a scanning pulse is also applied to the group electrode lines 21 to 27 formed by polar lines, and the detection signal SS (unindicated digital value) at that time is stored in a predetermined location of the RAM.

Next, the CPU, based on the digital value of this detection signal SS,
The contact position of the input pen 12 is determined.

The procedure for determining the contact position in the X direction is expressed by the fourth combination of FIG.
Expressed as A.

First, the CPU detects the signals SS3 to SS detected when the group electrode lines 3 to 6 are scanned by the first polar line in the X direction.
Compare the digital values of 6.

The signal SS having the maximum value among them is extracted. In the example of FIG. 4, signal SS4 is extracted. The fact that this maximum value signal is SS4 means that the input pen 12 is in contact with the area Z4 of the group electrode line 4 shown in FIG. Next, the CPU detects the group electrode lines 7 to 9 by the second electrode line in the X direction.
The largest one and the second one are extracted from the signals SS7 to SS9 detected during scanning. In the example of FIG. 5, the signal S88 is the largest one.

Also, the signal SS7 is detected as the second signal. The biggest one is SS8.

This means that the input pen 12 is in contact with the range Z8 in FIG.
This means that the input pen 12 is in contact with.

Therefore, from this result, the area where the signal SS shown in FIGS. 4 and 5 can be detected is the area where Z4 and Z87 overlap, that is, the area BB is the contact area of the input pen 12 at this time. . Note 1: This area can be specified by previously storing a table as shown in FIG. 6 in the ROM and applying the above determination result to the table. (In Fig. 6, the initial letter SS of the signals is omitted.) Regarding one area AA, the maximum signal SSS when the group electrode line is scanned by the first electrode line, and the maximum signal SS7 when the group electrode line is scanned by the second electrode line. When the second signal SS8 and Nasi.

It will be the same as that of area DE. Therefore, in this embodiment, the dummy electrode line 2Z is arranged next to the electrode line 1A as shown in Fig. 1, and it is connected to the group electrode line 9.
The second signal when scanning the second electrode line group in A is SS
9 to distinguish it from the area DE.

Note that when the area AA is made an unused area, it is not necessary to provide such a dummy electrode 2Z.

The above process is performed by group electrode lines 21 to 27 using Y-direction electrode lines.
The same process is performed for the signal SS obtained when scanning the contact area AA-LL in the Y direction.

Then, the CPU sends data TD indicating the respective contact areas in the X direction and the Y direction to a data processing device (not shown) or the like via the IO.

〔Effect of the invention〕

As explained above, according to the present invention, the detection speed can be improved without complicating the pattern.

Moreover, since the electrode wires are tied together for scanning, the number of parts for scanning is also reduced. In addition, in the present invention, the detection tip of the input pen can be simply grounded, so the number of parts can be reduced in this respect as well. Although the human body is imperfectly grounded, it is also possible to input the coordinates on the tablet with your fingertips without relying on the input pen, and in this case, the input pen itself is not required. .

In addition, in this embodiment, in order to specify the contact position, the largest signal among the signals when the first electrode wire scans the group electrode wire, the largest signal among the signals when the second electrode wire scans the group electrode wire, and Although the second one was used, the same result can be obtained by using the maximum signal related to the group electrode line caused by the first electrode line, the second one, and the largest signal related to the group electrode line caused by the second electrode line. The area can be specified.

[Brief explanation of drawings]

The figure shows one embodiment of the tablet input device of the present invention.
The figure shows the arrangement of electrode lines in the X direction, Figure 2 is a block diagram of the device, Figure 3 is a circuit diagram of driver DX1 in Figure 2, and Figure 4 is the output when scanning group electrode lines 5 and 6. FIG. 5 is a waveform diagram showing the output signal when the group electrode lines 7 to 9 are scanned, and FIG. 6 is a diagram showing a table for specifying the contact area. 1...First electrode wire, 2...
...Second electrode wire. 3-9.21-27...Group electrode wire. 11......Tablet, DXl, D
X2. DYl, DY2...Pulse application means, R8... Current detection means,
CPU, ROM, ILAM...Coordinate identification means. Figure 4: n okoshi season * y, 9 words in the form 5 Figure 5 Figure 5 Hakamada collection T-shi ξ tape 1 and 6th ward

Claims (1)

[Claims] A tablet in which first and second electrode wires are alternately arranged in parallel, the first electrode wires are connected in parallel every m, and the second electrode wires are connected in parallel every m+n, forming a group electrode wire; pulse application means for applying a scanning pulse to the group electrode wire; current detection means for detecting a charging current flowing through the group electrode wire when the scanning pulse is applied; A tablet input device comprising coordinate specifying means for specifying designated coordinates.