JPH0430047B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a coordinate input device for inputting the coordinate position of a character pattern using touch electrodes. [Prior Art] Conventionally, various input devices have been proposed for inputting and recognizing characters, figures, etc. For example, characters drawn on the tablet by a pen-shaped jig using detection lines arranged in a matrix in the X-axis and Y-axis directions on the tablet;
An input device that detects the coordinate position of a figure and converts it into a pulse signal, a device that inputs it to a CRT display device with a light pen, or a device that arranges push buttons in a matrix and follows the characters and figures. There are devices that turn on the necessary push buttons while the device is in the closed position. [Problems with the prior art] When inputting characters and figures by applying the principles of the conventional input devices described above to small electronic devices such as wristwatches, each of the conventional input devices has the following problems. . In other words, input devices using tablets and pen-shaped jigs require special jigs and are complex, and because they are small electronic devices, their surface area is small; for example, in the case of a wristwatch, In this case, it is necessary to overlap the time display section and the input section for characters and graphics, but for this purpose, the tablet must be transparent, but a transparent tablet is difficult to manufacture. In addition, in input devices that use push buttons, the detection accuracy of coordinate positions is determined by the number of push buttons, so in order to improve accuracy, the number of seals must be increased, so it is difficult to use small electronic devices. However, since it is a mechanical switch, it has poor durability and cannot be made transparent. [Object of the Invention] It is an object of the present invention to provide a coordinate input device that allows the coordinate position of character patterns such as characters and figures to be input with high precision even in small electronic devices by using touch electrodes. [Summary of the Invention] A plurality of touch electrodes are arranged in a matrix on an XY coordinate system, and when a human body such as a finger comes into contact with the plurality of touch electrodes when inputting a character pattern,
The contact capacitance component of each touch electrode is detected, and the human body contact coordinate position is detected and stored from the capacitance component of the touch electrode with the largest value of the detected contact capacitance component and the capacitance component of the adjacent touch electrode. This is a coordinate input device. [Embodiment] Hereinafter, an embodiment in which the present invention is applied to an electronic wristwatch having a function of displaying a preset message at an alarm time will be described with reference to the drawings. FIG. 1 is an external view of the electronic wristwatch. A transparent surface glass 2 is fixed to the top surface of the watch case 1, and the top surface of the surface glass 2 is further provided with 4×
A total of 16 transparent touch electrodes 3 are arranged in a matrix of 4 at regular intervals, and above the touch electrodes 3, a dot display section 4 consisting of a liquid crystal display device is also arranged. . Further, inside the watch case 1, in addition to electronic circuit components such as a timekeeping circuit, a liquid crystal drive circuit, and a character pattern processing circuit, a battery and the like are arranged. For convenience of explanation, the 16 touch electrodes are numbered S/0 to S/F in hexadecimal as shown in the figure. 2 and 3 are principle diagrams of the switching characteristics of the touch electrode 3. FIG. In FIG. 2, the watch case 1 is made of metal and is similarly worn on the wrist via a metal back cover (not shown). And watch case 1 has a high potential of power supply voltage.
It is connected to the VDD (logical value “1”) side and is also used as one touch electrode. For this reason,
When the human body touches the touch electrode 3 while the wristwatch is worn on the wrist, the touch electrode 3 can be turned on. Also, the symbol Cx is a stray capacitance component, which is
This is due to the electrode wiring capacitance caused by the wiring of the touch electrode 3 and the gate capacitance caused by the high input impedance of the gate of the CMOSIC used in this embodiment. Also, the code Cy is
This is the contact capacitance component of the human body that occurs between the watch case 1 and the touch electrode 3 when the touch electrode 3 is touched.
Therefore, the stray capacitance component Cx always exists, but the contact component Cy is artificially generated. Further, symbol A is a rectangular wave signal with a predetermined period (for example, 64 Hz), and this rectangular wave signal A is input to each gate of a CMOS inverter 8 consisting of a resistor 5, an N-channel MOS transistor 6, and a P-channel MOS transistor 7. There is. The source side of the transistor 6 is supplied with a low potential Vss (logical value “0”) of the power supply voltage, and the source side of the transistor 7 is supplied with a high potential via the watch case 1.
V _DD is supplied. The output signal of the CMOS inverter 8 is input to the touch electrode 3, and is also output as a signal B via the COMS inverter 9. That is, the signal B is a signal to be determined that is used to determine whether or not a human body is in contact with the touch electrode 3, that is, whether or not there is a touch. Therefore, when the touch electrode 3 is not touched by the human body, the rectangular wave signal A becomes a high potential level and is applied to the CMOS inverter 8 as shown in FIG. 3.
, the output signal of the COMS inverter 9 becomes a low potential level, and therefore the output signal of the inverter 9 becomes a high potential level. At this time, the output signal of the CMOS inverter 8 is affected by the stray capacitance component Cx, so the rise of the output signal of the inverter 9 is different from the rectangular wave signal A at time T0, as shown in FIG. Only late. Next, if a human body touches the touch electrode 3,
A contact capacitance component Cy is formed between the touch electrode 3 and the watch case 1, and this contact capacitance component Cy
is connected in parallel to the stray capacitance component Cx, so the output signal B of the inverter 9 only corresponds to the combined capacitance of the stray capacitance component Cx and the contact capacitance component Cy for the rectangular wave signal A. Output is delayed. Incidentally, the magnitude of the contact capacitance component Cy varies depending on the contact area between the human body and the touch electrode 3 or the contact state such as the pressing force, but is approximately proportional to the contact area. Therefore, the output signal B of the inverter 9 when the contact capacitance component Cy is small is the output signal [third] when the human body is not in contact with the touch electrode 3.
2], as shown in FIG. 3,
The rising edge is output with a further delay of time T1. Furthermore, when the contact capacitance component Cy is large, the output signal B of the inverter 9 is output with its rise delayed by the time T1+T2, as shown in FIG. 3 and FIG. In this way, the CMOS inverter 9
According to the output state of the output signal B, it is possible to know the magnitude of the contact capacitance component Cy, which is output as a value approximately proportional to the contact area. FIG. 4 explains the XY coordinate system set for the touch electrodes 3 arranged in a 4×4 matrix. This XY coordinate system further includes 12 touch electrodes 3 (symbols S/0, S/1, S/2, S/3,
S/
4, S/7, S/8, S/B, S/C, S/D, S/E
,S/F
The coordinate positions of 16×16=256 points are set in the coordinate plane connecting each center position of (respectively shown in ). And its XY coordinate position is point (0,0) ~
It is expressed by (15, 15). Next, with reference to FIGS. 5 and 6, the principle of inputting 256 coordinate positions on the XY coordinate system formed as shown in FIG. 4 will be explained. That is, in the case of the present invention, as described above, since the delay in the rise of the signal B is proportional to the contact capacitance component Cy, that is, proportional to the contact area, the delay amount of the signal B is calculated by a counter described later. By detecting this and calculating the detected value, the center coordinate position of the area currently in contact with the human body is determined. Therefore, in Figure 5a, the person's finger is now the symbol A,
This shows a state in which a plurality of touch electrodes 3 indicated by B, C, D, E, etc. are in contact at the same time. Also, at this time, the counter executes a counting operation for each touch electrode 3, and as a result, each touch electrode 3
A count value proportional to the contact area of each is detected. The control section, which will be described later, first finds the touch electrode 3 with the largest value from among these count values (in the illustrated example, the touch electrode 3 indicated by signal B), and then selects the touch electrode 3 with the largest count value. 3 at the center, each touch electrode 3 above, below, right, and left (as shown in FIG. 5b, symbol D,
Select the touch electrodes 3) indicated by E, A, and C, and use their respective count values to determine the center coordinate position of the current contact area indicated by diagonal lines. The direction and amount of deviation from the center coordinate position of the electrode 3) is calculated, and the coordinates of the center position of the current contact area are determined. In this case, the number of the touch electrode 3 with the maximum count value is Km, the count value of Km is B, the count value of the touch electrode 3 above Km is D, the count value of the touch electrode 3 below Km is E, If the count value of the touch electrode 3 on the left side of Km is A, and the count value of the touch electrode 3 on the right side of Km is C, then the coordinates of the center position can be determined from the five count values of ) to ). It is determined by the calculations performed on the axis. That is, FIG. 6 shows the calculation algorithm, and the horizontal axis is the center position of the touch electrode 3 (that is, points a, b, and c are the centers of the touch electrode 3, respectively, indicated by symbols A, B, and C). (indicating the position), and the vertical axis indicates the count value. Further, in the figure, a point S indicates the center position of the current contact area, its count value is S, and the coordinate position of the point S is determined by congruence of isosceles triangles. In Fig. 6, the intersection of straight line bc and straight line b'c' is P1, and Lc'P is on the left side of point a on straight line ab.
Take a point P2 where 1C=La'P2a. Further, let the intersection of straight line P2a' and straight line b'c' be point S', and let the intersection with the perpendicular line descending from this point S' to straight line ab be the aforementioned point S. Therefore, from the relationship △SS′P1≡△SS′P2, the following equation (1) is obtained, and as a result, equation (2)
is obtained. Note that the pitch of the touch electrode 3 (ie, the distance between points a and b, for example) is defined as lx, and the distance between point S and point b is defined as dx. B-C/lx=S-C/lx+bx=S-A/lx-dx...(1
) dx=lx/2・A−C/B−C (2) The same is true for the y-axis direction, and formula (3) is obtained. That is, dy=ly/2・D-E/B-E (3) Now, when formulas (2) and (3) are applied to the XY coordinates in FIG. 4, the following is obtained. That is, since this XY coordinate consists of points (0, 0) to (15, 15), lx=ly=5 (4). Also, change the numbers of the 16 touch electrodes 3 (5x,
5y), the values of x and y are 0, 1, 2, or 3. Km now =
(5xm, 5ym), its coordinate position (X, Y)
is (X, Y) = (5xm+5/2・A-C/B-C, 5ym+5/2・D-E/B-E) ...(5). However, if Km is the end electrode and there is no adjacent touch electrode 3, that is, xm = 0, xm = 3, ym
When =0 and ym=3, the count values C, A, E, and D are set to "0", respectively. As described above, in the XY coordinate system of FIG. 4, the center coordinate position of the current contact area can be found by calculating equation (5). Next, the circuit configuration will be explained with reference to FIGS. 7 and 8. The control unit 11 stores a microprogram that controls all operations of this electronic wristwatch, and outputs microinstructions AD, DA, 0P, and NA in parallel. Therefore, microinstruction AD is ROM
(read only memory) 12 and RAM (random access memory) 13 as address data. Also, the microinstruction DA is
It is applied as data to the RAM 13 or the arithmetic unit 14. Further, the micro-naming OP is applied to the operation decoder 15, so that the operation decoder 15 receives various control signals CS1,
Output CS2, R/W, X, Y, Z. Further, the microinstruction NA is applied to the address unit 16, and the address unit 16 outputs microinstructions AD, DA, OP, and NA for executing the next process from the microinstruction NA and signals d, e, and 16Hz, which will be described later. Address data for reading is output and applied to the control section 11. ROM12 contains standard vector strings for each character pattern of numbers and alphanumeric characters (described later).
is stored as data, and when the control signal CS1 is applied, the data is read out and given to the arithmetic unit 14. The RAM 13 has various registers as shown in FIG.
It is used for various processing such as timer processing and character recognition processing. Therefore, the T register is for storing the current time, and the A register is for storing the current time.
The register is for storing alarm time, the TM register is for storing timer time, and other registers will be described later. Further, in another area of the RAM 13, there is an area for storing data of the coordinate position (X, Y) calculated by the calculation of the above formula (5).
M1 to M4 are provided as shown in FIG. That is, the areas M1, M2, M3, and M4 are the coordinate position data (X,
Up to 20 Y) can be written each. Then, during the character recognition processing in the calculation unit 14,
From the data written in this way to each area M1 to M4 of the RAM 14, first, the total length of each stroke (stroke length) is calculated, and then each stroke length is divided into six equal parts, and the vector of each part is calculated. A process of determining and obtaining a vector string, further comparing this vector string with the standard vector string for each character pattern in the ROM 12, and determining the most similar character pattern of the standard vector string as the input character pattern data. is executed. In addition, RAM
13, data is read and written in accordance with control signals CS2 and R/W. The stroke and vector will be explained below. Figure 18 shows a state in which the number "2" with a stroke number of 1 is input from the touch electrode 3. As shown in Figure 18A, when character pattern data "2" is input, its coordinate position data is As described above, since this is the first stroke of the RAM 13, it is written to area M1.
Then, as shown in FIG. 18B, after calculating the stroke length of the first stroke, the stroke is divided into six equal parts. Then, as shown in Figure 18C, each equally divided point is approximated by a straight line from the starting point side to the ending point side, and the vector of each part is determined according to the vectors (8 types from 0 to 7) in Figure 19. and a vector sequence is calculated. FIGS. 20, 21, 22, and 23 show standard vector sequences for each character pattern with the number of strokes of 1, 2, 3, and 4, respectively.
It is stored in ROM12. Returning to FIG. 7, the calculation unit 14 receives the control signal
The various calculations described above are executed under the control of
Give to 7. In addition, when a jump calculation is executed, a signal d indicating the presence of calculation result data and a signal c indicating carry occurrence are outputted to the address section 16.
and outputs the next address. Under the control of the control signal Y, the dot display section 4 displays a message stored in advance for a certain period of time at the alarm time. Further, the input section 17 is composed of the touch electrode 3 and the like, and outputs the count value as input data under the control of the control signal Z, and supplies it to the RAM 13 and the calculation section 14 for processing. The oscillation circuit 18 constantly oscillates a reference frequency signal of, for example, 32.768 KHz and supplies it to the frequency dividing circuit 19. Then, the frequency dividing circuit 19 outputs a signal of 16 Hz, which is frequency-divided to 16 Hz, and is applied to the address section 16.
In response to this, the timing processing flow is executed once every 1/16 seconds. Next, the configuration of the input section 17 will be specifically explained with reference to FIG. The 4-bit data a output from the control section 11 is applied to the decoder 21 when character recognition processing is executed. This data a specifies the 16 touch electrodes T1 to TF numbered S0 to SF in Fig. 1 in a time-sharing manner, and the corresponding signal B from each touch electrode (see Fig. 3) This is for sequentially outputting. That is, the data a is decoded by the decoder 21 and converted into signals "1" to "16" which are sequentially output as high potential _VDD level signals, and are sent to the gates of the corresponding transmission gates G1 to G16, respectively. Supplied. Also, transmission gate G1~
The input side of G16 is the corresponding touch electrode T1~TF
The output terminals of the transmission guts G1 to G16 are connected to the output terminals of the transmission gates G1 to G16, respectively.
They are respectively connected to CMOS inverters 8 and 9 explained in the figure. and timing signal generation circuit 2
2 (this rectangular wave signal c has the same purpose as the rectangular wave signal A explained in FIG. 2) is applied as a gate control signal to the CMOS inverter 8 and the AND gate 23, respectively. ing. In addition, the timing signal generation circuit 2
2 outputs a high frequency signal d for causing the counter 25 to perform an actual counting operation, and applies it to the AND gate 23. Further, the output signal of the inverter 9 (the signal B) is inverted by the inverter 24 and supplied to the AND gate 23 as a signal e. As a result, the AND gate 23 outputs a signal f synchronized with the signal d, and the counter 2
It is applied to the clock input terminal CK of No. 5 and counted. Then, the count value X is
The data is sent to the RAM 13 and the calculation unit 14. As already mentioned, this count value X is proportional to the magnitude of the contact capacitance component Cy of the touch electrodes T1 to TF. Note that the clear input terminal CL of the counter 25 is cleared by the signal b output from the timing signal generation circuit 22 when each touch electrode T1 to TF is sequentially specified in a time-sharing manner. It is prepared for the counting operation of the touch electrode. Also, one end is connected to the high potential V _DD level, and the other end is connected to the low potential V _ss via the resistor 26.
The output of the AC switch connected to the level is sent to the control unit 11 via the transstate buffer 27.
It is sent as an AC signal. This is because the stray capacitance component Cx of the touch electrodes T1 to TF varies greatly depending on the environmental conditions, so when inputting a message, etc., turn on the AC switch in advance.
In response to this, the control unit 11 outputs the data a, scans the touch electrodes T1 to TF at least once, obtains a count value for each stray capacitance component Cx, and stores it in the RAM 13. It is provided. Next, the operation will be specifically explained with reference to the flowcharts shown in FIGS. 12 to 17. First, an overview of the overall operation will be explained with reference to the general flow shown in FIG. This general flow is the seventh
Execution is started every time a signal of 16 Hz is output from the frequency dividing circuit 19 shown in the figure, that is, every 1/16 seconds. First, the timekeeping process of step S1 is executed, and the calculation unit 14 performs a predetermined calculation on the previous data in the T register of the RAM 13 to calculate current time data. This current time data is then sent to the dot display section 4 and displayed. Next, timer processing in step S2 is executed.
This timer processing requires some processing to be performed for a certain period of time in the flow described later, and if a certain period of time is preset in the TM register, the specified period of time is subtracted each time this process is executed. Next, a process for determining whether or not the message setting mode is set is executed in step S3. In this judgment process, it is determined whether the message setting mode is set depending on whether a mode switch (not shown) for message setting is turned on or not, and if "YES", the step is executed. Proceeds to S8 and proceeds to the character recognition processing routine, on the other hand,
If "ON", the process advances to step S4.
In this judgment process, it is judged whether or not the alarm time preset in the AL register has been reached.
If ``YES'', the process advances to step S5, where the message data is read out from the RAM and displayed, and when it is displayed for a certain period of time, this is determined in step S6, and the message disappears in step S7. be done. On the other hand, step S4,
When it is determined "NO" in S6, this general flow process ends, and other processes (not shown) are started. Further, when it is determined in step S3 that the message setting mode is set and the process proceeds to step S8, it is determined in step S8 whether or not the flag FA in the RAM 13 is "0". Normally, this flag is set to "0" when character recognition processing is not being executed, and the process then proceeds to step S9, where data "1" is set to the flag FA.
It is stored that character recognition processing is being executed. Then, in accordance with the flow described later, the character pattern recognition process whose coordinates are input from the touch switches T1 to TF of the input unit 4 is executed (step S10).
Then, the input message data is stored in RAM1
3 (step S11), and is further displayed and confirmed on the dot display section 4 (step S12), after which the flag FA is cleared and the character recognition processing execution state is released. Note that in step S8, the flag
When FA is not "0", the process returns to the process being executed previously. FIG. 13 is a flowchart showing the specific content of the character recognition process in step S10.
That is, when entering the character recognition processing step, first, the initialization processing of step SA is executed.
The specific contents of this initialization process are shown in FIG. First, in step SA, flags F1 and F2 in the RAM 13 are both set to data "1", and both the stroke number counter Z and the counter n in the RAM 13 are cleared. Next, proceed to step SA2 and
It is determined whether or not the switch has been turned on. If the switch has not been turned on, the process proceeds to another processing routine, and if it has been turned on, the process enters data input processing in step SE. The content of this data input process consists of a two-step process shown in the flowchart of FIG. That is, the data a for sequentially specifying the touch electrodes T1 to TF in a time-division manner begins to be output. In this case, data a (data n) is "1"
Since it is incremented one by one, data a
As shown in the time chart of FIG. 11, the contents of (data n) change to correspond to the numbers S0 to SF set for the touch electrode T1.
First, the stray capacitance component Cx when the human body does not touch the touch electrode T1 after the AC switch is turned on at the touch electrode T1 is determined as the count value X of the counter 25. That is, a high potential V <sub>DD</sub> signal "1" is output from the decoder 21 and applied to the transmission gate G1 to open it. Therefore, the stray capacitance component of the touch electrode T1 at that time is
Depending on the magnitude of Cx, a signal e that falls with a delay from the rise of the rectangular wave signal C is output from the inverter 24 as the output of the touch electrode <sub>T1</sub> , and
Enter 3. As a result, as shown in FIG. 11, both the rectangular wave signal C and the signal e reach the high potential V <sub>DD</sub>
The AND gate 23 is opened only during the level period, and a signal f synchronized with the signal d is outputted, which is applied to the clock input terminal CK of the counter 25 and counted to obtain the count value X (step SE2). Next, the process proceeds to step SA3, where the count value X1 of the touch electrode T1 (currently, data n is "1", so X1
The result data of adding a constant value ξ to ) is
It is written to the Yn register (n=S1 shown in FIG. 9) of the RAM 13. This process is performed in order to take into consideration the fluctuation of the stray capacitance component Cx, the coefficient error of the counter 35, etc., set ξ=2 to 3, and keep the stray capacitance component at a slightly larger value. Next, proceed to step SA4, and check whether the data n is SF or not, that is, the entire process from touch electrodes T1 to TF is performed.
After it is determined whether or not each stray capacitance component Cx has been detected, the process proceeds to step SA5, where data n is incremented by 1 to become "2", and detection of the stray capacitance component Cx of the touch electrode T2 is started. The subsequent processing is exactly the same as that for the touch electrode T1, and the steps are
SE, SA3 to SA5 are repeated 15 more times, and as a result,
The XS1 to XSF registers in RAM13 each have
After turning on the AC switch, the human body is still touching the electrode T1.
~Each stray capacitance component Cx when TF is not touched is stored, and the corresponding YS1~YSF registers are
A correction value of the stray capacitance component Cx obtained by adding a constant value ξ is stored. When the initialization process SA is completed, the next step SB is the touch process. The details of this touch processing are shown in the flowchart of FIG. First, in step SB1,
The M register in RAM13 is cleared, and
Counter n is reset. Next, the data input process in step SE is executed in the same way, but
In this case, when the character pattern of the number "2" is input by touching the XY coordinates of the touch electrodes T1 to TF with a human body such as a finger, for example, as shown in FIG. Stray capacitance component of
A count value X based on the combined capacitance of Cx and the contact capacitance component Cy is detected. And at this time, the 8th
The operation in the figure is the same as described above, so the explanation will be omitted. First, when the count value X1 (when n=1) of the touch electrode T1 is detected, the step
Proceeding to SB2, the calculations of X1 to Y1 are executed. In other words, the stray capacitance component Cx is calculated from the count value X1 based on the combined capacitance of the stray capacitance component Cx and the contact capacitance component Cy.
Based on the count value Y1 (now as a correction value)
Y1 register (that is, held in the YS1 register), the result data, in other words, a count value based only on the contact capacitance component Cy is calculated, and the T1 register (indicated by TS1 to TSF in FIG. 9) is calculated. written to. Next, in step SB3, a judgment process is executed to determine whether or not the data in the T1 register is greater than the data in the M register (currently "0").
Proceeding to SB4, the data in the T1 register is transferred and held in the M register, and the data of counter n (currently n=1) is transferred and held in the m register.
Therefore, each process in steps SB3 and SB4 is performed by sequentially detecting the contact capacitance components of the touch electrodes T1 to TF.
This is a process to find the maximum value among the count values based only on Cy, that is, the contact capacitance component
Cy is for detecting the touch electrode with maximum. Next, in step SB5, touch electrodes T1 to TF
It is determined whether or not all have been detected, the counter n is incremented by 1, and detection of the touch electrode T2 is started. Thereafter, steps SE, SB2 to SB6 are repeated 15 more times, completing one set of touch processing for the touch electrodes T1 to TF. During this time, by executing steps SB3 and SB4, the number of the touch electrode with the largest contact capacitance component Cy detected as a result of the current touch processing is stored in the m register, and the number of the touch electrode with the largest contact capacitance Cy is stored in the m register. The count value for component Cy is stored in the M register. When the touch processing is completed, the process proceeds to step SC1, where it is determined whether the data in the M register is greater than "0". That is, it is a judgment process to determine whether or not the human body has already touched any of the touch electrodes T1 to TF.If the character pattern has been input and the human body has touched it, as already mentioned, the data in the M register is
“0” is greater, so step SC2
Proceed to. Then, in step SC2, flag F
It is determined whether or not 1 is ``1'', and since it is ``1'', the process proceeds to step SC3, where the TM register is preset for a certain period of time and a timer is started. This is a process in which a character pattern input within a certain period of time set in the TM register is treated as one character. Next, the process advances to step SC4, where flag F1 is cleared. and step
Proceeding to SC5, it is determined whether flag F2 is "1" or not. Since it is currently "1", the process proceeds to step SC6, where the stroke number counter Z is incremented by 1 and becomes "1", and the first stroke is started. The contents are shown below. Next, the flag F2 is cleared at step SC7, and then the key-in processing at step SD is started.
The details of this key-in process are shown in the flowchart of FIG. In this key-in process, first, in step SD1, the number (S0 to SF) of the touch electrode with the largest contact capacitance component Cy stored in the m register is converted into coordinates (xm, ym).
Therefore, these coordinates are xm=0, 1, 2, 3, ym=0, 1, 2, 3 in the XY coordinate system of Figure 4.
For example, S
The coordinates of touch electrode T1 at 0 are (3, 3).
Note that these coordinates (xm, ym) are in the RAM13.
They are stored in the xm register and ym register, respectively. Next, proceed to step SD2, and check whether xm is "0" or not, that is, in FIG. 4, the rightmost number is S3,
S7, SB, SF touch electrodes T3, T7, TB,
It is determined whether or not it is TF, and if so, a correction process is performed in step SD3 when determining the coordinates based on equation (5). That is, the C register in the RAM 13 is cleared (that is, the contact capacitance component of the right touch electrode is "0"), and the A register has touch electrodes T2 with numbers S2, S6, SA, and SE, respectively. , T6, TA, and TE, each data in the TS1 to TSF registers is transferred. On the other hand, if the data of Xm is not "0" at step SD2, the process advances to step SD4.
Furthermore, it is determined whether or not Xm is "3", that is, whether or not the leftmost touch electrodes T0, T4, T8, and Tc whose numbers are S0, S4, S8, and SC in FIG.
If so, in order to correct equation (5), the A register is cleared (that is, the contact capacitance component of the left touch electrode is "0"), and the C register contains:
Touch electrodes T1 with numbers S1, S5, S9, SD,
TS1 required for T5, T9, TD
~Data in the TSF register is transferred. Further, if the data of Therefore, in that case, the numbers S4, S5,
Touch electrodes T4, T5, T8, T9 of S8, S9
The data in the TS1 to TSF registers required for the data are transferred, and the touch electrodes T6, T7, T7, numbered S6, S7, SA, SB are transferred to the C register.
Data in the TS1 to TSF registers required for TA and TB is transferred. The above is the process of correcting the X-axis direction when determining the center coordinates of the current contact area using the above equation (5). This is a correction process. And steps SD7, SD8, SD9,
SD10 and SD11 correspond to the steps SD2, SD3, and
They correspond to SD4, SD5, and SD6, respectively, and are self-explanatory, so a detailed explanation will be omitted. When each of the above processes is completed, the calculation process of equation (5) in step SD12 is executed, the center coordinates (xs, xs) of the current contact area are calculated, and the xs in the RAM 13 is calculated.
Temporarily stored in register and ys register respectively. In this case, the data of the maximum contact capacitance component is now M
Since it is stored in a register, the above step
In SD12, data M is written instead of data B. Further, data S takes values from 0 to 19 (see RAM 13 in FIG. 10). Once the center coordinates (xs, ys) are determined in this way, the process proceeds to step SD13, where the current coordinates (xs, ys) are changed to the previous coordinates (xs-1, ys).
-1), that is, whether the finger is stopped at one place and the center coordinates have not changed. If it has changed, the process proceeds to step SD14.
The coordinates (xs, ys) are stored at address 0 in the first stroke area M1 of the RAM 13 shown in FIG. Then, the S register in the RAM 13 is incremented by 1 and becomes "1". On the other hand, if it is determined in step SD13 that the center coordinates have not changed, the process immediately returns to the touch processing in step SB. With the above steps, the center coordinates of the first address of the first stroke of the input character pattern data have been obtained, and steps SB, SC1 to SC7, and SD are repeated until the finger leaves the touch electrodes T1 to TF. The process is repeated, and during this time the data S changes by 1 from 2 to 19, with a maximum of 19 center coordinates (xs, ys)
are written in addresses 1 to 19 of the area M1. Also, for the 2nd, 3rd, and 4th strokes of a 2-stroke character (for example, "4"), a 3-stroke character (for example, "F"), and a 4-stroke character (for example, "E"), Similarly, if a character is input within the timer time set in the TM register, the area in RAM 13 is
Up to 20 center coordinates (xs, ys) are written in addresses 0 to 20 of M2, M3, and M4, respectively. On the other hand, after executing the initialization process in step SA, the touch process in step SB is executed, but in the next step SC1, it is determined that M>0 is not true because the human body has not touched the touch electrodes T1 to TF yet. If so, proceed to step SC8,
It is determined whether the flag F1 is "1". Since it has already been set to "1" in the initialization process, the process returns to the touch process in step SB.
Then, step SB, SC1, until the human body touches the
SC8, SB, ... are repeated. Also, if flag F1 is set to "1" at step SC8,
If not, the process proceeds to step SC9, where it is determined whether the flag F2 is "0" or not. Then "0"
Otherwise, jump to step SC11, and on the other hand,
If it is "0", the flag F2 is set to "1" in step SC10, and then the process advances to step SC11. In step SC11, it is determined whether the timer time has elapsed or not, and if it has not elapsed, the step SC11 is performed.
Proceed to SC12. When the character pattern is input within the timer time and the process proceeds to step SC12, the flag F1 is set to "1" in step SC12. Then, proceed to step SC13, but for example,
As shown in Fig. 18, if we input the number "2", which corresponds to one stroke, the center coordinates (xs, ys) for that one stroke are maximum 20, RAM1
3 is already stored in area M1. For this reason,
At step SC13, each center coordinate (xs, ys) is tracked to calculate the length of the first stroke, that is, the stroke length. Then, in step _SC14 , the calculated stroke length is divided into six equal parts, as shown in FIG. 18B, and the coordinates of the dividing points are determined.
Next, in step SC15, as shown in FIG. 18C,
Connect the starting point and the dividing point, the dividing point and the dividing point, and the dividing point and the ending point, and according to the vector diagram in Figure 19, 6
Determine each belt of the two divisions and obtain a vector sequence. The vector sequence obtained from the column C in FIG. 18 is "175570". Next, in step SC16, the vector sequence is
Compare with the standard vector string in ROM12. In this case, since the character is a one-stroke character, the direction difference of each component is determined with respect to the standard vector of each character shown in FIG. 20, and then the sum of the direction differences is determined. In other words, the components of the standard vector sequence are "a1a2a3a4a5a6",
The components of the detected vector sequence are "b1b2b3b4b5b6"
Then, first, the difference between each component (a1−b1), (a2−b2)
...Find (a6−b6). As a result of this -7
The value of ~ +7 is calculated, but in the case of -4 ~ +4,
The absolute value is the direction difference, and in the case of -7 to -5, it is 1
The value converted to ~3 is 3 to 1 if it is +5 to +7.
The sum of these six direction differences is determined by using the converted value as the direction difference. For example, if we take the standard vector string "467012" of the character "0" among the standard vectors in Figure 20,
Between the vector sequence "175570", 4-1=
3, 6-7=-1, 7-5=2, 0-5=-5,
After each calculation of 1-7=-6, 2-0=2, find the direction difference 3, 1, 2, 3, 2, 2, 3+1+2+3
The sum of directional differences of +2+2=13 is found. The same applies to other characters "0", "1", "2", etc. Then, in step SC17, the character with the minimum value is extracted from the sum of the direction differences determined as described above, and that character is determined as the input character. Then step SC18
In step SC17, it is determined whether or not multiple characters have been output as similar characters. If multiple characters have been output, step SC19 is further executed.
The detailed characteristics of the input characters are checked and determined. In this case, examples of input characters that are determined to be similar characters are, for example, the characters "P" and "D", "I" and "F", etc., as shown in FIG. In the case of "P" and "D", the 1st and 2nd strokes
The determination is made by comparing the magnitude of the distance between the stroke end point and the end point. As a result, one character is extracted from the plurality of similar characters (step SC20), and that character is displayed on the dot display section 4 as the input character pattern, and is also stored in the RAM 13 as message data. On the other hand, if the minimum sum of differences is one character at step SC18, that character is immediately taken as the input character. Furthermore, in cases where the total number of strokes is 2, 3, or 4, each of the processes in steps SC13 to SC17 is the same as the process for the first stroke for the second, third, and fourth strokes. Of course, other processing is executed. However, in the above embodiment, it is arranged in a 4×4 matrix.
Although 16 touch electrodes arranged along the XY coordinate system were used, the number of touch electrodes is not limited to 16 and may be arbitrary. In addition, the XY coordinate system was composed of 256 points arranged in a 16 × 16 matrix;
The scale of the coordinate system is also not limited to the above embodiment. Furthermore, in the above embodiment, the number of strokes of characters to be input was set to a maximum of 4 numbers and alpha alphabets, but the number of strokes can be arbitrary, and the types of characters can also be katakana, hiragana, kanji, symbols, and even arbitrary figures. It may be. Further, although the stroke length is divided into six equal parts, the number of divisions is not limited to six but may be arbitrary. Furthermore, the present invention is applicable not only to electronic wristwatches but also to other electronic devices. [Effects of the Invention] As explained above, the present invention arranges a plurality of touch electrodes in a matrix on an XY coordinate system,
When a human body such as a finger contacts the plurality of touch electrodes when inputting a character pattern, the contact capacitance component of each touch electrode is detected, and the contact capacitance of the touch electrode with the maximum value of the detected contact capacitance component is determined. Since we have provided a coordinate input device that detects and stores the human body contact coordinate position from the contact capacitance component of the adjacent touch electrode, we have provided a coordinate input device that detects and stores the human body contact coordinate position from the contact capacitance component of the adjacent touch electrode. It is possible to input character pattern coordinates easily and with high precision, and has the advantage of being able to be used in a variety of applications.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is an external view of an electronic wristwatch of the same example, FIG. 2 is a configuration diagram showing the basic principle of the invention, and FIG. 3 is a diagram showing a time chart thereof. Fig. 4 is a configuration diagram of the XY coordinate system, and Fig. 5 is a diagram showing an example of the contact state of a human body to the touch electrode 3 and four touch electrodes 3 extracted around the touch electrode 3 with the maximum contact capacitance component. , Fig. 6 is a diagram explaining the calculation algorithm for determining the center coordinates of the human body contact area, Fig. 7 is an overall circuit configuration diagram, and Fig. 8
The figures are specific circuit diagrams of the input section 17, Figures 9 and 10.
The figures are a diagram conceptually showing the configuration of the RAM 13,
FIG. 11 is a time chart for explaining the operation of the input section 17, FIGS. 12 to 17 are flow charts for explaining the operation, and FIG. 18 is a vector sequence for the number "2". Figure 19 is an explanatory diagram of vectors, and Figures 20, 21, 22, and 23 are illustrations of character patterns with stroke numbers of 1, 2, 3, and 4, respectively. FIG. 24 is a diagram showing a standard vector sequence, and is a diagram showing an example of similar character patterns. 1... Watch case, 2... Surface glass, 3, T
1~TF...Touch electrode, 4...Dot display section,
Cx... Stray capacitance component, CY... Contact capacitance component,
8, 9...CMOS inverter, 11...control unit,
12... ROM, 13... RAM, 14... Arithmetic unit, 15... Operation decoder, 16...
Address section, 17... Input section, 18... Oscillation circuit, 19... Frequency division circuit, 21... Decoder, 22
... Timing signal generation circuit, 23 ... AND gate, 24 ... CMOS inverter, 25 ... Counter, G1 to G16 ... Transmission gate, AC ... AC switch.

Claims (1)

[Scope of Claims] 1. A plurality of touch electrodes arranged in a matrix, and detecting contact capacitance components when a human body simultaneously contacts at least two touch electrodes among the plurality of touch electrodes. contact capacitance component detection means; maximum contact capacitance component touch electrode discriminating means for determining the touch electrode having the maximum value among the contact capacitance components of each touch electrode detected by the contact capacitance component detection means; The maximum contact capacitance component determined by the touch electrode discriminating means is calculated based on the ratio of the contact capacitance component of the touch electrode and the contact capacitance component of the touch electrode adjacent to this maximum contact capacitance component touch electrode. A coordinate input device comprising: a coordinate position detection means for obtaining coordinate data corresponding to a center position; and a storage means for storing the coordinate data obtained by the center coordinate position detection means.