JPS59202577A - Graphic input device - Google Patents

Abstract

PURPOSE:To improve resolution by providing a means where a potential induced in the XY electrode of a tablet is stored and obtaining a ratio of sum/difference of the stored potential to calculate a horizontal position. CONSTITUTION:When the tablet 1 is touched with a pen 5, a detection signal is scanned by a scanning pulse and is stored in a storage device 23. The storage device 23 consists of three registers M1-M3, and the detection signal is stored in registers M1-M3 successively. A comparing circuit 26 takes out a maximum level Vmax and a next level Vnext from registers M1-M3 and sends them to a calculating part 27. The calculating part 27 calculates the ratio of sum/difference of them and gives it to a distance calculating part 28. The output of the calculating part 28 is sent to a coordinate determining part 29. Thus, the coordinate of the pen in the horizontal direction is detected with high resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a graphic input device, and particularly to a graphic input device that improves the accuracy and resolution of coordinate reading in a capacitively coupled tablet.

Among the graphical human power devices, the tablet input device is a device that can directly convert information existing as a graphic into the form of coordinate values and input it digitally, such as blueprints and maps.

It is widely used for input and data analysis of weather maps, ocean observation, survey data, etc., and for human input such as handwritten characters and shapes. In the capacitive coupling method, multiple electrode wires are laid in parallel at equal intervals inside the tablet, and there are two electrode wires between the input pin or cursor and the electrode wires. ]11 It is a tablet that uses the full capacity to detect pulse voltages sequentially applied to electrode wires and determines the position coordinates of an input pen, etc., but the resolution is improved by narrowing the spacing between the electrode wires completely. When I try to do so, the electrode wire #lf
l<, there is a risk of wire breakage, and it becomes difficult to maintain sufficient parallelism between the wires.Therefore, as a practical matter, it is nearly impossible to manufacture a tablet with a large input area, and 'fC8 As an attempt to solve this problem, conventional methods have been to find the ratio of the detected voltages of the three electrode lines near the pointing point of the input pen, calculate the pointing position from the geometric relationship, and calculate the minimum resolution of the device. A method has been proposed in which the pitch is smaller than the pitch between electrode lines (Japanese Patent Publication No. 19380/1983).

However, in the above-mentioned conventional technology, y-1'-(α, #
j: fixed i)・・・・・・・・・・・・・・・(1
) The relationship α・d holds approximately, and furthermore, it is attempted to avoid fluctuations in constants caused by non-uniformity of the mechanical dimensions and materials of the device by determining the ratio of detection voltages, but experiments show that Even when there is no mechanical deviation of the device, there is a large error between the distance calculated based on equation (1) above and the actual measured value, making the validity of the approximation questionable, and it has the disadvantage of poor measurement accuracy. Furthermore, in order to find the position, a fractional formula with the quadratic formula of the voltage ratio as the denominator and numerator is used, making calculations cumbersome and the circuit configuration complicated, and special calculation formulas are required near the edges of the tablet. There was this inconvenience.

The present invention has been made in view of the drawbacks of the prior art, and an object of the present invention is to provide a graphic input device that can improve measurement accuracy and resolution with a simple configuration.

The present invention provides a tablet formed by laying a plurality of X, and at least two detected
The above object is achieved by comprising means for storing two electric potentials, and means for calculating the horizontal position of the detecting means on the tablet by calculating the ratio of the sum/difference of the electric potentials stored in the means. It is something.

First, the principle of the present invention will be explained based on FIGS. 1 to 4. As shown in FIG.
are disposed orthogonally to each other and spaced apart from each other in parallel, and an insulating layer 3 is integrally attached above the X electrode lines Xo and Xn. Input bear 5' on this tablet 1! +
7 When the scanning pulse shown in FIG. 2 is applied to each electric @ line Xo-Xn or Yo-Yn by touching the pen directly or indirectly through the drawing paper 6, the voltage is induced in the input pen 5 by capacitive coupling. For example, it is as shown in Figure 3 for Ir No. 11.

Detection signal a1 related to electrode line X1vc closest to input ben 5
is J'1 and the large level Vmax, and the detection signals ai1, ai+1 gradually increase as the distance from the input pen 5 increases.
The level becomes lower to ゜ai-2. Here, the distance function Ls is calculated for the signal levels of the two electrode lines x, , 'x, -1 that sandwich the input bend 5, that is, the maximum level Vmax and the second thickest signal level Vnext.

When we calculate the correspondence between the horizontal distance S from the midpoint of the electrode lines X1-1 and Xi to the touch point 1 of the input ben 5, we find that there is a substantially linear relationship as shown in Figure 4. be.

Therefore, by determining the ratio of the sum and difference of the two detected voltages, the position indicated by the input valve 5 can be determined.

Next, one embodiment of the present invention will be described based on FIGS. 5 to 7.

Is Fig. 5 a tablet input device according to the present invention? ? , 'f is a block diagram illustrating. In the figure, an input bench 5 for drawing figures with a tablet 1-H or inputting 1-1 shapes by following the drawings on a drawing paper 6 is equipped with a pen switch 5A, and the human-powered pen 5 When the tufflet 1 is pressed down, the pen switch 5A is closed and the entire device is put into operation. The pen switch 5A is connected to a control circuit 10, and when the pen switch 5A is closed, a pen switch signal is sent to the control circuit 10. The control circuit 10 is energized by the pen switch signal and starts a control operation, and performs pulse scanning of the master tablet 1 according to a predetermined sequence. That is, the control circuit 10 sends a start signal to the counter 11VCy to cause the counter 11 to count the clock signal output from the oscillator 12. The counted value of the counter 11 is sent to the X decoder 14 or the Y decoder 15 via the X or (or a game controlled by switching in the X direction) 13 by the control circuit 1o. The X and Y decoders 14 and 15 are connected to the X and Y electrode lines Xo of the tablet 1, respectively.
Xn, yO to Yn1 are connected, and the X, Y
The decoder 14, IFi selects an electrode line corresponding to the count value and sequentially applies scanning pulses (see 2nd month). Hereinafter, we will discuss scanning in the X direction as an example of fμ. The scanning pulse is such that the input pen 5, which is capacitively coupled to the tablet 1, detects the pulse applied to the electrode wire near the input pen 5 in contact with the input pen 5.

The detection signal detected by the human-powered sensor 5 is amplified by the amplifier 16, and is then amplified by the input sensor 5 (C).
and a second conhaler that extracts a group of detection signals that are a combination of the detection signals related to the two electrode lines sandwiching the bend touch point of the input bend 5, that is, the detection signal of the maximum level and the detection signal of the second +m3 level. At step 18, signals are distributed. Now, Tablet 1 in the range of Electrode Wire Xi 2~X1 edition
Increased by 1ii when all the upper bent touch points are changed to the X direction.
The detected signal level after i and i is as shown in FIG. The threshold value of the first comparator 17 and the second comparator 1
The threshold values of 8 are each set to the level indicated by Ipi%J (+2) in the same figure. Therefore, the detection signal passing through the first comparator 17 is always one VC, and the second
The number of comparators 18 is 1b and 12) detection'Iii is two or three.

The output side V of the first comparator 17 (is the shaping circuit 1
9 is connected, and after the detection request waveform is shaped, the counter 11 is used as a latch strobe signal.
is sent to the latch circuit 20 into which the count value of is input.

When this latch time hh 20 &, ↓, latch strobe signal is input, the counting box of the MiJ recording wanton 11 at that timing is latched. Latch circuit 20v (The latched data indicates the position i of the electrode line closest to the input ben 5, and the data is output to the coordinate determining section 29, which will be described later.

An Al1) converter 22 is connected to the output side of the amplifier 16 via a hold circuit 21, so that the level of each detection signal is sequentially A-to-D converted. The A/D converted detection signal level data is
The data is stored in a storage unit 23 that includes first to third registers M1 to M3 connected to the output side of the D converter 22. The input sides of the first to third registers M1 to M3 are connected in series, and data is sequentially shifted from the first register M1 to the third register M3 by a clock pulse synchronized with a detection signal. The clock pulse n for this shift operation is generated by shaping the waveform of the output of the TJ'x 2 comparator 18 in a shaping circuit 24 and applying a predetermined delay in a delay circuit 25.

Each of the first to third registers M1 to M3 of the storage unit 23 is
Tablet) 1 is cleared before starting the X-direction scan, and in one scan, the second comparator 18
When two detection signals are output from the second register M2, the data is stored in the second register M2, and the data output later is stored in the third register M1. "0" is 1. If the second comparator 18 outputs three detection signals, @ means the third to
Data related to the previous detection signal is stored in the order of the 11th/register 3 to M1. In FIG. 6, the bend touch point of the input bend 5 is connected to the X electrode line Xi 1r −1 on the tablet 1.
1, -" From 2 to
The two detection signals output from the comparator 18 are H.
, and three detection signals are output for i, I
II range. The level of each detection signal a1-2 to ai+1 for the bent touch point of P1 to P7 is equal to V1 to
The storage state in the third registers M1 to M3 is shown in (1) in FIG.
~(shown in force.

Each of the first to third registers/11 to M3 of the storage section 23
The output side of is connected in parallel to a comparison circuit 26, and this comparison circuit 26 detects the maximum detection signal level Vmax and the second largest detection signal level Vnext from among the data stored in the first to third registers M1 to M3. The system is designed so that the selection is carried out. These two levels Vmax, Vne
This is related to the two electrode lines X1-1 and X that sandwich the bent touch point of the xt id input capen 5. However, the comparator circuit 26 determines whether the bent touch point is on the left or right side when viewed from the midpoint BO between the X electrode lines X1-1 and X, based on the positional relationship of the registers in which the Vmax and VneXt data are stored L7 has a function of determining whether the coordinate determination unit 29 is correct and outputting an addition signal or subtraction signal of “+” or “-” to the coordinate determination unit 29.

Vmax, Vne output from the comparison circuit 26
The two data of xt are sent to Ls complaint 4 calculation 27. This TJS 91 Santo 27 has the input Vmax, Vn
ext +y)% Based on the data, calculate the ratio of the sum/difference of the detection signal voltage according to equation (2) 4, and calculate the value of IJS (≧0)
is calculated and the result is output to the distance calculation unit 28. The distance calculation unit 28 calculates the distance S from the BO corresponding to the LsO value (≧
0) is calculated by reading data from the memory using the address Ls as 45j! according to the scale diagram in FIG. It is sent to the determining unit 29. In addition, here, the thickness h of the drawing paper 6 etc. on the tablet 1 is assumed to be constant 7, and calculation is made according to the Ls-8 line for hvC. The S value calculated in this way is sent to the coordinate determining section 29.

This coordinate determining unit 29 uses the maximum level electrode line position data i output from the latch circuit 20 and the distance calculating unit 28.
When the comparator circuit 26 outputs an addition signal based on the S&''C output from the electrode line XO,
That is, 1=i-1, and when the ball is bent to the left of the BO shown in FIG. 6, X= i -f+(1/2-S)...
According to the formula (3),
The comparator circuit 26 outputs a reduced η- signal (i.e.,
I was touched by the right side of the BO, @UbaX21・”-(1/2-3)・・・・・・・・・
. . . The position is determined by calculating the X coordinate according to equation (4). The coordinates in the y direction can also be determined in exactly the same manner.

Incidentally, in the above embodiment, the case was explained where the thickness h of the manufactured paper was constant, but if the thickness changes, the LS and S lines in FIG. 4 also change, and therefore It becomes necessary to make corrections. Therefore, as shown in FIG.
The total value of $1 is determined by line L (the height of the drawing paper, etc., in other words, the height 11 from the top surface of the tablet 1 to the tip of the input pen 5 is calculated, and the distance is calculated based on the value of h. Part 28
and the thickness standard determination unit 29, and the fixed correction unit 31Q calculates S′−=−(a・h+1)−5,−, ,,−,,−・
・・・－・・・・・・・・・(6) (However, l and a are positive, and by multiplying by correction terms such as linear approximation and quadratic approximation, which are determined experimentally, -[S' is obtained and the horizontal position is By performing this thickness correction, measurement errors caused by uneven mechanical dimensions of the tablet 1 and dents caused by the pressure f of the input ben 5 can also be removed. As shown in the figure, a plurality of Ls divided by h
-8 line table may be prepared and the table corresponding to hK determined by the thickness detection circuit 30 may be drawn to determine S11i'+. -1: Thickness 1 in formula (())
Instead of finding 1, as shown in FIG.
is attached, and the distance between the metal plate 42 pasted on the back side of the paper presser 41 and the tablet 1 is detected by the proximity sensor 43, etc., and the height of the drawing paper 6 is determined. Good too.

As explained above, according to the present invention, the required calculation formula is very simple, so Kr
Positioning can be performed quickly with a simple configuration, and
The measurement accuracy and resolution are significantly the same.

[Brief explanation of drawings]

Figure 4 does not show the partial structure of the tablet.
1, Figure 2 is a timing chart of the scanning pulse, Figure 3 is approximately 2 diagrams showing the detection number 18 after amplification by the input vent, Figure 4 is a diagram related to the principle of the present invention, and Figure 5 is the diagram of the present invention. A block diagram showing a tablet insertion device according to an embodiment of the present invention is shown in Fig. 6, which shows the detection signal level at each point when a person moves in the fx direction on the tablet. i explanatory diagram shown in FIG. 7 (1) to (7) iq! : 7 masterpiece explanatory diagram showing a small portion of the data stored in the storage unit, FIG. 8 is a Glock diagram showing another embodiment, block diagram showing a modification of FIG. 8, claw 10 [': 21f felled 1n I
It is a schematic partial cross-sectional view showing an example of an IFj detection method of Lever-1-1
22...8/J) converter, 23... Storage unit, 27... Ls calculation unit, 28... Distance calculation unit, 29
. . . Coordinate determination unit, 30. .L1 level detection circuit, 31.
...Correction unit, 41...Paper presser, 42...Metal plate, 4
3... Proximity sensor. Patent applicant Pentel Co., Ltd. - 4,4P agent Patent attorney Mu Takahashi 15311.2゜su,
゛Figure 7 (M3) (M2) (Ml)t (2)■2

Claims (2)

[Claims] (1) A tablet formed by laying a plurality of X and Y electrode wires at regular intervals, a means for applying a scanning pulse to each of the electrode wires, and a tablet (according to the scanning pulse).
(A means for detecting the induced potential, a means for storing at least two detected potentials, and a ratio of the sum/difference of the potentials stored in the means is determined to determine the horizontal position of the detecting means on the tablet. A graphic input device comprising means for calculating. (2) A tablet comprising a plurality of X and Y electrode wires laid at one-foot intervals, means for applying a scanning pulse to each of the electrode wires, and a tablet K-inducing according to the scanning pulse. means for detecting the detected potential; and at least two detected potentials.
means for storing two electric potentials; and means for detecting the horizontal position and correcting the horizontal position.