JPH04246713A - Coordinate input device - Google Patents

Abstract

PURPOSE:To prevent the omission of an input point and the division of a stroke which occur in the case chattering is generated at the time of inputting a character and a graphic, and also, to surely recognize the inputted character and graphic. CONSTITUTION:In the case of inputting coordinate data in a pressing position by pressing a pressure sensitive tablet 21 on which a resistance film sheet is superposed and formed with an input pen, a tablet voltage detecting circuit 24 can detect generation of chattering, based on a voltage value corresponding to a resistance value of the pressure sensitive tablet 21 at the time of pressing. A CPU 25 eliminates from an input the coordinate data at the time when generation of chattering is detected by the tablet voltage detecting circuit 24, and also, executes processings for correcting and averaging the input coordinate data except the eliminated coordinate data, by which an omission of an input point and a division of a stroke caused by chattering are prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive coordinate input device used as an input device for OA (office automation) equipment.

0002

[Prior Art] A conventional pressure-sensitive coordinate input device is equipped with two resistive film sheets, and when the resistive film sheets are pressed with an input pen, the contact resistance value between the two resistive film sheets is measured. Some devices are configured so that the X and Y coordinates of the pressed position are input based on the pressed position.

In this pressure-sensitive coordinate input device, chattering may occur when the input pen switches between a contact state and a non-contact state with respect to the resistive film sheet, and the sensitivity of the resistive film sheet may be uneven. Similarly, in such cases, chattering may occur because the dividing resistance value is not constant.

[0004] Therefore, the conventional pressure-sensitive coordinate input device is
In order to prevent such chattering from affecting coordinate input, coordinates are not input while chattering occurs when the input pen switches between contact and non-contact states with the resistive film sheet. , is configured to be able to be handled using hardware and software.

[0005] In addition, in conventional pressure-sensitive coordinate input devices, when the input pen presses the resistive film sheet not only when switching between the contact state and the non-contact state, but also when the input pen is in the contact state, the pressure is weak. For example, when inputting a straight line stroke, the pressure from the input pen is generally weaker at the midpoint between the start point and the end point. There has been a problem in that the contact voltage between the terminals becomes low and chattering occurs, causing the coordinates of the input position to jump to an unexpected point.

[0006] Therefore, the conventional pressure-sensitive coordinate input device is
As described later, the coordinates of the input positions are averaged so that the input coordinates do not jump to unexpected points and characters or figures are not divided in the middle of the stroke.

FIG. 6 is an explanatory diagram for explaining the coordinate reading operation of a conventional pressure-sensitive coordinate input device.
A) is a timing chart thereof, and FIG. 6(B) is a timing chart in which the time axis of FIG. 6(A) is expanded.

As shown in FIG. 6(A), when sampling n reading coordinates used for averaging processing of input position coordinates in an interval (time interval) t, a coordinate input device equipped with The sampling period of the A/D conversion circuit is t/n (=ta).

As shown in FIG. 6(B), CF is the operation start timing for checking the occurrence of chattering before reading the coordinates, x is the start timing of the X coordinate reading operation, and y is the start timing of the Y coordinate reading operation. The start timing and CR are operation start timings for checking the occurrence of chattering after reading the coordinates.

[0010] Therefore, the conventional pressure-sensitive coordinate input device is
In each section t, a chattering check is started at timing CF before the first (first) coordinate reading,
That is, it is determined whether the input pen is in contact with the resistive film sheet or in a non-contact state, and if it is determined that the input pen is in contact with the resistive film sheet,
Start reading the coordinates and Y coordinates respectively. After reading the X and Y coordinates, start checking for chattering at timing CR, and if no chattering is detected, check for chattering before reading the next (second) coordinate, and check the X coordinate of the second coordinate. After reading the X and Y coordinates of the last (n-th) coordinate in the section t,
Start checking for chattering at timing CR. If the occurrence of chattering is not detected by this check, the data of the read n coordinates is averaged, and the input coordinates are configured to not jump to unexpected points and cause characters and figures to be split in the middle of the stroke. .

[0011]

[Problem to be Solved by the Invention] In such a conventional pressure-sensitive coordinate input device, the sampling period t is set for each section t.
Since the data of n coordinates that have been read after reading the nth coordinate in the last periodic section of a are averaged, the processing time for this averaging is equal to the sampling period ta.
If the length becomes longer, there is a problem that n·ta >t and averaging processing cannot be performed.

Therefore, the present invention ensures sufficient processing time for correcting and averaging the read coordinate data, thereby preventing occurrences in the middle of a stroke or insufficient sensitivity of the resistive film sheet when inputting characters or figures. Coordinate input can prevent missing input points and split strokes caused by chattering that occurs when the coordinates are uniform, and can also contribute to reliable recognition of input characters and shapes. It provides equipment.

[0013]

[Means for solving the problem] A pressure-sensitive tablet,
A coordinate data conversion means capable of inputting coordinate data of a pressed position on the tablet, a detection means capable of detecting occurrence of chattering based on a voltage value corresponding to a resistance value of the tablet at the time of pressing, and a detection means capable of detecting occurrence of chattering. It is equipped with a processing means for removing coordinate data inputted when detected, and correcting and averaging input coordinate data other than the removed coordinate data, and processing means necessary for inputting coordinate data by the coordinate data conversion means. The sum of the time and the processing time for correction and averaging by the processing means is configured to be shorter than a predetermined time.

[0014]

[Operation] When the coordinate data of the position where the tablet is pressed is input by the coordinate data conversion means, if the detection means detects the occurrence of chattering based on the voltage value corresponding to the resistance value of the tablet at the time of pressing, the processing means removes coordinate data input when chattering occurs, and corrects and averages input coordinate data other than the removed coordinate data. Further, the configuration is such that the sum of the time required for inputting the coordinate data by the coordinate data conversion means and the processing time for correction and averaging by the processing means is shorter than a predetermined time.

Therefore, sufficient processing time for correcting and averaging the read coordinate data can be secured, and only valid coordinate data can be input, so strokes can be avoided when inputting characters and figures. It is possible to prevent missing input points and split strokes caused by chattering that occurs in the middle of the process or when the sensitivity of the resistive film sheet is uneven. This can help ensure that the process is carried out reliably.

[0016]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of a pressure-sensitive coordinate input device according to the present invention, and FIG. 3 is a perspective view showing a schematic configuration of the pressure-sensitive tablet 21 of FIG. 2.

As shown in these figures, the pressure-sensitive coordinate input device according to the present invention includes a pressure-sensitive tablet 21, a driver circuit 22, an A/D conversion circuit 23, a tablet voltage detection circuit 24, and a CPU (central processing unit). device) 25, ROM (read only memory) 26, and RAM (random access memory) 27.

The pressure sensitive tablet 21, as shown in FIG.
A resistive film sheet 11 and a resistive film sheet 12 for respectively inputting the X and Y coordinates of the pressed position when the input pen 13 is pressed are integrated with a spacer (not shown) sandwiched between them, and are superimposed. It is made up of the following:

As shown in FIG. 2, terminals XH and XL are formed at the left and right ends in the X direction of the resistive film sheet 11 for inputting the X coordinate, which constitutes the pressure sensitive tablet 21, and terminals XH and XL are respectively formed for inputting the Y coordinate. Terminals YH and YL are formed at the upper and lower ends of the resistive film sheet 12 in the Y direction, respectively.

A coordinate input voltage can be applied to each of these terminals XH, XL, YH, and YL by the driver circuit 22, as will be described later.
Terminal XH according to the divided resistance value of the pressing position of the input pen 13
, XL, YH, and YL are determined by A/D.
It is configured to be read by a conversion circuit 23 and converted into a digital value.

Each voltage value converted into a digital value by the A/D conversion circuit 23 is configured to be read by the CPU 25, and the CPU 25 converts the voltage value into a digital value by the driver circuit 2.
2 terminals XH, XL, YH and YL.

In the tablet voltage detection circuit 24, a voltage of, for example, 5V is applied by the driver circuit 22 to the left end terminal XH of the resistive film sheet 11, and the right end terminal XL and the upper and lower end terminals YH and YL of the resistive film sheet 12 are connected to each other. When the input pen 13 switches between a contact state and a non-contact state with respect to the resistive film sheet 11 based on the voltage value of the terminal YL at the lower end of the resistive film sheet 12 when both are opened,
The configuration is such that chattering that occurs when the input pen 13 is weakly pressed while the input pen 13 is in contact with the resistive film sheet 11 can be detected.

The ROM 26 is connected to the CPU 25, and stores in advance a program for the CPU 25 and data on a threshold voltage VSH for determining the occurrence of chattering, which will be described later.

The RAM 27 is connected to the CPU 25 and is used to store input data of X and Y coordinates.
It has 5 work areas, etc.

Driver circuit 22 and A/D conversion circuit 23
is an embodiment of the coordinate data conversion means of the present invention. The tablet voltage detection circuit 24 is an embodiment of the detection means of the present invention. The CPU 25, ROM 26 and RAM 27 are one embodiment of the processing means of the present invention.

A method of reading and inputting the X and Y coordinates of the pressed position using the voltage values of the terminals XH, XL, YH and YL according to the divided resistance value of the pressed position of the input pen 13 will be explained.

For example, a voltage of 5 V is applied from the driver circuit 22 to the terminal XH at the left end of the resistive film sheet 11, and a voltage of 0 V is applied to the terminal XL at the right end. By opening both YH and YL, the X coordinate of the pressed position of the input pen 13 can be read and input from the voltage value of the terminal YL at the lower end of the resistive film sheet 12.

Similarly, the driver circuit 22 applies a voltage of 5 V, for example, to the terminal YH at the upper end of the resistive film sheet 12, and applies 0 V to the terminal YL at the lower end, and also applies a voltage of 5 V to the terminal YH at the upper end of the resistive film sheet 11, and terminals XH and XL
By opening both the resistive film sheet 11
The Y coordinate of the pressed position of the input pen 13 can be read and input from the voltage value of the rightmost terminal XL.

Next, the timing of reading coordinates in the coordinate input device of this embodiment will be explained.

FIG. 4 is an explanatory diagram for explaining the coordinate reading operation of the coordinate input device according to the present invention, and FIG.
) is its timing chart, and FIG. 4(B) is a timing chart in which the time axis of FIG. 4(A) is expanded.

As shown in FIG. 4(A), the interval (time interval) t consists of reading the coordinate data of a plurality of (n) coordinates,
It is also a period for correcting and averaging the read coordinate data, and the number n of coordinates read in the interval t is usually less than 10. Further, the sampling period of the A/D conversion circuit 23 is set to a value within the range of t/10 to t/40.

Therefore, the coordinate input device of this embodiment has n
Even excluding the processing time for reading the coordinate data of the read coordinates, correcting and averaging the read coordinate data, there is a free time of 10% of the number t within the interval t, and the read coordinate data The configuration is such that sufficient processing time for correcting and averaging can be secured.

As shown in FIG. 4(B), in the first sampling period of section t (value within the range of t/10 to t/40), the CF checks the occurrence of chattering before the first coordinate reading. x is the start timing of the X-coordinate reading operation, y is the start timing of the Y-coordinate reading operation, and CM is used both as a chattering check after reading the coordinates and a chattering check before the next coordinate reading. This is the operation start timing for checking the occurrence of chattering. Further, CR is the operation start timing for checking the occurrence of chattering after the last (nth) coordinate reading.

The interval t corresponds to a predetermined time according to the present invention.

Next, we will discuss the operation of the above embodiment, especially the CPU 2.
The operation of step 5 will be explained.

FIG. 1 is a flow chart for explaining the operation of the coordinate input device shown in FIG.

As shown in the figure, first in step S1, the CPU 25 activates the driver circuit 22 as described above.
By controlling the voltage, a voltage of 5V is applied to the leftmost terminal
and the terminals YH and YL at the upper and lower ends of the resistive film sheet 12 are both opened, and the terminal Y at the lower end of the resistive film sheet 12 is opened.
The voltage of L is checked from the A/D conversion circuit 23 by the voltage VT.
Read as AB.

Next, check voltage VTAB at this time
and the threshold voltage VSH, and if VTAB>VSH does not hold continuously for a plurality of sampled coordinates, it is determined that the input pen 13 is in a non-contact state with the resistive film sheet 11, and the process proceeds to step S1. Repeat the action.

On the other hand, if VTAB > VSH is established continuously for a plurality of sampled coordinates, it is determined that the input pen 13 is in contact with the resistive film sheet 11 and that no chattering is occurring. Step S
Proceed to 2 or below. (Check Cf) In step S2, as described above, by controlling the driver circuit 22, the terminal XH at the left end of the resistive film sheet 11 is checked.
For example, 5V is applied to the terminal XL at the right end.
0V is applied to the resistive film sheet 1, and terminals YH and YL at the upper and lower ends of the resistive film sheet 12 are both opened.
2 is read from the A/D conversion circuit 23 (X coordinate reading input).

Next, in step S3, the pressing force of the input pen 13 against the resistive film sheet 11 becomes small during the stroke of a character or figure, and chattering occurs.
Furthermore, chattering may also occur if the sensitivities of the resistive film sheets 11 and 12 are uneven.
The reading voltage VX of the X coordinate is corrected as follows.

[0042]VX=(Vcc/VTAB)×VXI
N Here, Vcc is 5 (V), VTAB is the chattering check Cf that starts at timing CF, and the chattering check C that starts at timing CM.
The check voltage at m and VXIN are the voltages at the X coordinate from the A/D conversion circuit 23.

After this correction, the process advances to step S4.

[0044] In step S4, similarly to step S2,
By controlling the driver circuit 22, the resistive film sheet 1
For example, 5V is applied to the upper end terminal YH of the resistive film sheet 11, and 0V is applied to the lower end terminal YL of the resistive film sheet 11. The voltage at terminal XL of is A/
Read from the D conversion circuit 23 (Y coordinate reading input).

Next, in step S5, similarly to step S3, the Y coordinate reading voltage VY is corrected as follows.

[0046]VY=(Vcc/VTAB)×VYI
N Here, VYIN is Y from the A/D conversion circuit 23
is the voltage at the coordinates.

After this correction, the process advances to step S6.

In step S6, the presence or absence of chattering is determined by the chattering check Cm starting at timing CM or the chattering check Cr starting at timing CR, and then steps S2 to
It is determined whether the data of the X and Y coordinates obtained in S5 is valid. That is, if VTAB>VSH holds true, the coordinate data is determined to be valid and the process proceeds to step S8. Also, VTAB
>VSH is not established and the coordinate data is determined to be invalid, the process proceeds to step S7, the data of the coordinate is skipped, and the process proceeds to step S8.

In step S8, it is determined whether or not the coordinate data of n coordinates have been input, and if so, the process advances to step S9. If no input has been made, the process advances to step S11.

In step S11, the check voltage VTAB at this time is compared with the threshold voltage VSH, and VTAB
>VSH is not established, it is determined that the input pen 13 is not in contact with the resistive film sheet 11, and the operation of step S11 is repeated.

On the other hand, if VTAB>VSH is established, it is determined that the input pen 13 is in contact with the resistive film sheet and that no chattering has occurred, and the process proceeds to step S2 and subsequent steps. (Check Cm) In step S9, as shown in FIG. 5, the n×n coordinate data read so far is averaged, and in step S10
Proceed to.

In the following step S10, the averaged coordinate data is stored in the RAM 27.

Therefore, at the timing of the coordinate reading operation of the conventional coordinate input device shown in FIG. Since the occurrence of chattering is checked, the time for checking can be shortened, and the processing time for correcting and averaging the read coordinate data can be set even longer.

Next, the averaging process of the coordinate data in step S9 will be explained.

FIG. 5 is an explanatory diagram showing the averaging process in the flowchart of FIG.

As shown in the figure, an averaged coordinate point m is first calculated by calculating the average of the coordinate data of n coordinates for the X and Y coordinates.

Next, among the n coordinate points read this time, if there is a point that is more than a predetermined distance a from the averaged coordinate point m, that point is removed and the previous averaged coordinate point is removed. The average of the n coordinate data is calculated again for the X and Y coordinates, and the averaged coordinate point m
Find ´. This is to prevent the error of the averaged coordinate point m from increasing due to coordinate points that have moved away from the coordinates that should have been input due to chattering. Point m'
is located near the previously averaged coordinate point m-1.

Next, the averaged coordinate point k is obtained by calculating the average of the current averaged coordinate point m (or m') and the previous averaged coordinate point m-1.

Therefore, this averaged coordinate point k becomes closer to the previously averaged coordinate point m-1, and the n scattered coordinate points In, In-1, In
-2, In-3, etc. coordinate data can be converged.

According to the above-described embodiment, sufficient processing time for correcting and averaging the read coordinate data can be secured, so that when inputting characters or figures, there is no need to worry about resistance occurring in the middle of a stroke. It is possible to prevent missing input points and split strokes caused by chattering that occurs when the sensitivity of the membrane sheet is non-uniform. Moreover, this makes it possible to reliably recognize input characters and figures.

[0061]

As explained above, the present invention provides a pressure-sensitive tablet, a coordinate data conversion means capable of inputting coordinate data of a pressed position of the tablet, and a voltage value corresponding to the resistance value of the tablet when pressed. a detection means capable of detecting the occurrence of chattering based on the detection means; and a detection means capable of removing coordinate data input when the occurrence of chattering is detected by the detection means, and correcting and averaging input coordinate data other than the removed coordinate data. and processing means for performing the processing, and is configured such that the sum of the time required for inputting the coordinate data by the coordinate data conversion means and the processing time for correction and averaging by the processing means is shorter than a predetermined time. .

Therefore, it is possible to secure sufficient processing time to correct and average the read and input coordinate data, and since only valid coordinate data can be input, it is possible to input characters and figures easily. It is possible to prevent missing input points and split strokes caused by chattering that occurs in the middle of a stroke or when the sensitivity of the resistive film sheet is uneven. This can contribute to ensuring that the recognition of

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining the operation of the coordinate input device of FIG. 2;

FIG. 2 is a block diagram showing an embodiment of a pressure-sensitive coordinate input device according to the present invention.

3 is a perspective view showing a schematic configuration of the pressure-sensitive tablet of FIG. 1. FIG.

FIG. 4 is an explanatory diagram for explaining the coordinate reading operation of the coordinate input device according to the present invention.

FIG. 5 is an explanatory diagram showing the averaging process in the flowchart of FIG. 1;

FIG. 6 is an explanatory diagram for explaining a coordinate reading operation of a conventional pressure-sensitive coordinate input device.

[Explanation of symbols]

11, 12 Resistive film sheet 13 Input pen 21 Pressure sensitive tablet 22 Driver circuit 23 A/D conversion circuit 24 Tablet voltage detection circuit 25 CPU 26 ROM 27 RAM

Claims (1)

[Claims] 1. A pressure-sensitive tablet, a coordinate data conversion means capable of inputting coordinate data of a pressed position of the tablet, and detecting occurrence of chattering based on a voltage value corresponding to a resistance value of the tablet when pressed. and processing means for removing input coordinate data when occurrence of chattering is detected by the detection means, and correcting and averaging input coordinate data other than the removed coordinate data. and is configured such that the sum of the time required for inputting the coordinate data by the coordinate data conversion means and the processing time for correction and averaging by the processing means is shorter than a predetermined time. coordinate input device.