JP3078950B2 - Handwriting input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handwriting input device, and more particularly to a handwriting input device that uses a resistive tablet and displays a handwritten input image on a liquid crystal display device.

[0002]

FIG . 9 is a perspective view of a conventional handwriting input device.

A liquid crystal display 73 is used for display, and a transparent resistive tablet 72 is provided on the liquid crystal display 73.
Are superimposed, and these are fitted into the cabinet 75. Also, in this cabinet 75,
A circuit board and a power supply for detecting position coordinates input to the handwriting input device and displaying the detected coordinates are provided. The input by the handwriting, configurations and the stylus pen 74 use Irare is done by drawing characters and figures on the surface of the tablet 72
Has become.

[0004] Also, as the general structure of the tablet 72 as described above is shown in FIG. 10, the film 98 and glass 9
The transparent conductive films 96a and 96b are deposited on each of the substrates 9. A minute transparent insulating resin 97 is uniformly dispersed between the transparent conductive films 96a and 96b, and the transparent conductive films 96a and 96b are adhered through the transparent insulating resin 97. At the time of input, the tip of the stylus pen 74 comes into contact with the tablet upper surface 91, and when further writing pressure is applied, the transparent conductive films 96a and 96b come into contact with each other. At this time, the resistance value in the X-axis direction and the resistance value in the Y-axis direction are converted into a voltage, and when a certain value is reached, it is recognized that the input has been performed.

Further, a principle of detecting the coordinates of the input position will be described below with reference to FIG. 11 which is a diagram.

FIG. 16 shows the principle of detecting the coordinate position in the Y-axis direction (the vertical direction of the screen).

A constant DC voltage is applied to the upper and lower electrodes on the glass side by a power source for coordinate detection via wiring electrodes. At this time, a voltage having a voltage gradient as shown in the graph is applied to the transparent electrode on the glass side. Now, when the point P on the film 98 on the upper surface side is pressed with the stylus pen 74, the transparent electrode film 96a deposited on the back surface of the film 98 on the upper surface side, and the transparent electrode film 96a deposited on the surface of the glass 99 on the lower surface side, 96b contacts. This contact area changes depending on the area of the tip of the pen and the pen pressure. At this time, the voltage V _det detected is taken out from the transparent electrode film 96a of the film 98 and taken out as a digital value by the A / D converter, whereby the coordinates in the Y-axis direction can be detected. The detection in the X-axis direction is performed in the same manner, except that the connection to the coordinate detection power supply and the A / D converter is exchanged for the detection in the X-axis direction.

When the pen pressure is detected by the above operation, it is necessary to detect the pen pressure based on the change in the contact resistance between the upper and lower transparent electrodes. In this case, the contact area of the upper and lower electrodes differs between when the tablet is pressed lightly and when the tablet is pressed strongly. In order to detect this contact area, after detecting the coordinates, an appropriate load is connected to the V _det input of the A / D converter to intentionally cause a voltage drop in V _det . When the contact area is large (high pen pressure), the voltage drop is small, and when the contact area is small (pen pressure is low), the voltage drop is large. The pen pressure can be detected by detecting such a change in the voltage drop.

A stylus pen 74 is shown in FIG.
An independent pressure sensor 93 for detecting pen pressure
This is the configuration. The pen tip 91 of the stylus pen is supported by a built-in spring 92, and a pressure sensor 93 detects the applied writing pressure via the spring.

First, when a pen pressure is applied to the pen tip 91, the pressure is input to a pressure sensor 93 linked to the pen tip, and is converted into a change in resistance value. Further, the amount of change in the resistance value is converted into a voltage value by the resistance / voltage converter 94.
This voltage value becomes the output of the pressure sensor 93, and this voltage value is converted into a digital value by A / D conversion. The output information to be displayed is selected according to the correspondence between the digital value and the preset output voltage (digital value) -display output information.

[0011]

By the way, in the conventional example ,
There, if the resistive type tablet is used, it is possible to utilize the change in the detection voltage to detect the pen pressure,
In order to facilitate the detection of the pen pressure, it is necessary to increase the area of the pen tip and to take care that the two electrodes are deformed by the pen pressure to change the contact area more greatly. However, the area of the pen point and the degree of deformation of the tablet are closely related to the ease of writing. That is, it is difficult to write when the area of the pen tip is too large, and to write with the pen tip small, it is necessary to detect a very small change in contact resistance as a change in writing pressure. For this reason, there is a problem that a highly accurate A / D converter is required. Further, when the contact area is made small, a further problem is that mse during the transition period of contact.
An unstable state occurs when the upper and lower electrodes come into contact with or separate from each other in the order of c, so that the pen pressure detection level must be increased in advance. As a result, there is a problem that a subtle change in the pen pressure cannot be detected. Furthermore, as the tablet changes over time, the pen pressure for detecting the coordinate position must increase, but from the familiarity of everyday use, the worker notices that the change in resistance to pen pressure is small. There was also a problem that it was difficult.

Further, in the configuration in which the pressure sensor is built in the input pen side, when the pen pressure detection and the coordinate detection are separately performed, even if the pen pressure is increased and the input is performed due to the deterioration of the tablet, the input is performed on the detection side. There is also a problem that it cannot be distinguished whether the writing pressure has increased due to the deterioration of the characteristics or whether the writing pressure has simply been increased.

The present invention all SANYO was made in order to solve these problems, and an object thereof is to provide a handwriting input device capable of displaying a Check boss was pen trajectory.

[0014]

In order to achieve the above object, a handwriting input device according to the present invention will be described with reference to the basic conceptual diagram shown in FIG. A tablet 32 that detects an input when a voltage value output by an external pressing force reaches a predetermined value;
A pen for inputting handwritten information to the tablet 32, a display unit 37 for displaying a locus of the information at a coordinate position where the input of the handwritten information is detected, and a drive signal for driving the display unit 37 are supplied. in handwriting input device including a display drive control unit 36, to the pen is provided a pressure sensor 31 for detecting the pen pressure, and the tablet 32 is first
Multiple tablets on the tablet set when used
Predict the reference pen pressure value, which is the average of the pressure values at the coordinate position.
And that the input of handwritten information is detected.
Storage means 33 for storing the output value of pressure sensor 31
And the output of the pressure sensor 31 when handwritten information is input.
Calculation means 3 for performing a calculation for subtracting the reference pen pressure value from the force value
4 and determine the thickness of the line to be output according to the calculation result
The determined information is supplied to the display control drive unit 36.
And a display driving means
The control unit 36 calculates the calculation result obtained by the calculation unit 34
Displayed in a graph showing the state of deterioration of the tablet based on the
Information on the tablet to be displayed on the display unit 37.
It is characterized by being constituted as follows .

[0015]

According to the present invention, the storage means 33 stores the reference pen pressure value in advance.
Is stored, and input of handwritten information is detected
Since the output value of the pressure sensor 31 is stored, the relative difference from the pressure value actually applied to the pen is calculated.
The determination information is supplied to the display drive control unit 36 by the determination means 35, and the pen input locus is displayed on the display unit. Also, the display drive control unit 36 adds
Display a tablet degradation status based on the
Information of the tablet to be supplied to the display unit 37
So, it is possible to quantitatively inform the deterioration state of the tablet
it can.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a handwriting input device applied to the present invention will be described.
The hardware configuration will be described. FIG. 2 shows its appearance, and FIG.
2 shows a schematic cross-sectional view taken along the line AA in FIG. Below
A detailed description will be given based on these drawings.

In the device of this embodiment, a resistive film type tablet 2 is superimposed on a liquid crystal display panel 3, and the periphery of the tablet 2 except for the display surface is a cabinet 5.
It is sandwiched between. A pair of protrusions 5a and 5b for sandwiching the tablet 2 are provided at positions facing each other, and furthermore, a pressing portion 9a whose tip is elastically pressed to the tablet 2 side integrally with the protrusion 5a. clip 1 that has been formed. By a clip 1 of this, transparent sheet 6 such as paper or OHP paper on the tablet 2
Is fixed .

The circuit of the present embodiment having the above hardware configuration
A block diagram is shown in FIG. In the following, based on FIG.
The configuration of the embodiment will be described.

The pressure sensor section 11 is built in the pen side,
The pen pressure applied to the pen is input as a resistance value, and the resistance value is converted into a voltage value and output. The output value of this is A
Is converted to a digital value via the / D conversion unit 11a,
It is stored in the AM 101. In the tablet unit 12, the transparent conductive films facing each other due to the pressing of the pen are in contact with each other, and the resistance value in the X-axis direction and the resistance value in the Y-axis direction at this time are converted into a voltage, and the value is present. The configuration is such that an input is recognized when the value becomes a constant value. The output value of the tablet unit 12 is output to the A / D converter 12
The data is converted into a digital value via a and stored in the RAM 101. The CPU 101 performs a later-described calculation in accordance with the converted digital value and the information of the pressure versus output voltage of the pressure sensor unit 11 written in the read-only memory ROM 102, stores the result in the RAM 101, and based on the calculation result. The pen pressure value is corrected, and a drive signal is supplied to the liquid crystal drive unit 14 so as to display a pen input locus corresponding to the corrected pen pressure value. The image is displayed on the liquid crystal display unit 15 by the driving of the liquid crystal drive unit 14.

Further, a keyboard section 13 for performing key input, a buzzer sound generating circuit 16 for forming a signal for generating a buzzer sound in response to the key input from the keyboard section 13, and a buzzer sound are generated. Buzzer sound generator 17
Is provided.

In this embodiment, in this configuration, the value of the pressure sensor in the pressure sensor section 11 is not used as the pen pressure as it is, but the value of the pressure sensor when it is determined that a pen input has been made on the tablet is used. As a standard,
The difference from the actually input pressure value is calculated, and based on the calculation result, the actual writing pressure value is obtained, and a line having a thickness corresponding to the writing pressure value is displayed on the liquid crystal display unit 15. Thus, a driving signal is supplied to the liquid crystal driving unit 14.

Here, the above-mentioned pen pressure correction function will be described in detail. First, the circuit shown in FIG.
In the embodiment , since the coordinate position detection reference pressure value _Psi is not set in the initial state of use, the pen pressure correction processing is performed together with the tablet position correction. FIG. 5 shows a processing flowchart of the pen pressure correction.

First, a tablet position, a pen pressure correction screen, and a pen pressure level are displayed. These screens are shown in FIG . The pen pressure level display at the center of the screen indicates the state of the pen pressure level. By looking at this level, the deterioration state of the tablet can be known. The tablet position is corrected by sequentially touching the cross patterns indicated by the broken lines at the four corners of the screen with the input pen (STEP.1).

Next, when the input pen is pressed against the tablet, the output voltage from the pressure sensor section increases in accordance with the pressure of the input pen, as shown in FIG . When the pressure exceeds a certain value, tablet electrode contact occurs. In the early stage of contact, contact and non-contact unstable states occur,
When the pressure at the point A is reached, a stable contact state is established, and coordinates can be detected at a voltage value equal to or higher than the detection voltage V _det . The CPU 101 reads a change in the detected voltage value of the tablet unit 12 via the A / D conversion unit 12a, and
The output voltage of the pressure sensor 11 at the time when the change of the _det value _stops is read via the A / D converter 11a. The pressure P _s at this time is a coordinate position detected pressure, also the pen-pressure detecting start pressure. In this state, the pressure of the input pen is further increased. When the pressure reaches the detection upper limit of the pressure sensor, the point B becomes the writing pressure detection maximum pressure P _sm . Therefore, the range that can be detected as pen pressure is P _sm -P _s (STEP.2).

Next, it is determined whether or not the initial pen pressure has been set. If the initial pen pressure has not been set, the process ends. If the initial pen pressure has been set, the process proceeds to (STEP.4) (STEP.3).

In (STEP.4), when coordinates are detected for each point, the CPU 101 changes the touched point into a solid cross, generates a pen input detection sound from the buzzer generator 17, and sets the pressure / voltage of the input pen. The converted values are stored in the RAM 101 as the coordinate position detection pressure values _Ps1 to _S4 . After detecting all coordinates four points, it calculates the average value of the pressure values P _s1 ~ _S4 of four points, as the coordinate position detected pressure value P _s RAM 10
1 is stored. After terminating position detection of the four points, entering a specific code from the keyboard 17 of the apparatus, the coordinate position detected pressure value P _s when this is stored in the RAM101 as the coordinate position detecting reference pressure value P _si, reference tablet deterioration detection And This reference value P _si becomes the reference pen pressure value P _si .

[0027] In normal use, running the tablet position correction, CPU 101 is a coordinate position detected pressure detected by the tablet position correction value P _s and the reference brush pressure value P
It calculates the difference P _s -P _si and _si, and displays the value as the length of the bar. Since the maximum value of the length of the bar is predetermined, the length of the bar becomes longer as the tablet deteriorates and becomes the maximum, indicating that it is the life of the tablet and it is time for replacement.

As described above, the pressure / voltage conversion value at the time of coordinate detection when the apparatus is used for the first time is stored in advance as the coordinate position detection reference pressure value, and the pressure / voltage conversion value at the time of coordinate detection during use is stored each time. The comparison with the value makes it possible to quantitatively notify the user of the deterioration state of the tablet.

Here, the pen pressure detection processing at the time of actual handwriting input will be described below with reference to FIG .

CPU 101 detects pen input coordinates from the tablet (STEP. 1). Next, the pen pressure P at the time when the XY coordinates are read is read from the pressure sensor unit 11 via the A / D converter 11a (STEP.2). Read pen pressure P
If, performs calculation of the brush pressure difference ΔP between the pen-pressure detecting starting pressure P _s that is set in advance, the brush pressure difference ΔP and its X-
The Y coordinate is stored in the RAM 101. This pen pressure difference ΔP makes it possible to display a pen input trajectory having a thickness corresponding to the pen pressure (STEP.3).

[0031]

As described above, in the handwriting input device of the present invention, the pen is provided with the pressure sensor for detecting the pen pressure .
Tab set when the first tablet is used
The average of the pressure values at multiple coordinate positions on the
The reference pen pressure value is stored in advance, and
Record the output value of the pressure sensor when a force is detected.
Storage means and the pressure sensor when handwritten information is input.
Calculating means for performing a calculation for subtracting the reference pen pressure value from the output value;
The thickness of the line to be output is determined according to the calculation result,
To supply the determined information to the display control drive unit
Means, and the display drive control unit obtains the
Indicates the tablet deterioration status based on the calculated results.
Display tablet deterioration information to be displayed on a graph
Since the configuration and supplied to the section, display contents to be outputted,
A pen input locus with stable writing pressure can be displayed without being affected by the deterioration of the tablet. In addition, it is possible to quantitatively notify the deterioration state of the tablet.
The user can understand the status of the equipment at any time and maintain it.
Nonce can be performed appropriately.

[Brief description of the drawings]

FIG. 1 is a basic conceptual diagram of the present invention.

FIG. 2 is an external view of an embodiment of the present invention.

FIG. 3 is a schematic sectional view of AA in FIG . 2;

FIG. 4 is a circuit block for explaining an embodiment of the present invention .
Figure

FIG. 5 is a flowchart of a pen pressure correction process according to the embodiment of the present invention .
Art

FIG. 6 shows a liquid crystal display unit for explaining an embodiment of the present invention .
Diagram showing display contents

FIG. 7 illustrates a pressure sensor according to an embodiment of the present invention .
Diagram showing output voltage

FIG. 8 is a flowchart of a pen pressure detection process according to the embodiment of the present invention .
Art

FIG. 9 is a perspective view of a conventional handwriting input device.

FIG. 10 shows the structure of a pressure-sensitive tablet.

FIG. 11 is a diagram illustrating the principle of voltage detection in a pressure-sensitive system.

FIG. 12 is a diagram illustrating the structure of a conventional input pen.

[Description of Signs ] 31 ··· Pressure sensor 32 ··· Tablet 33 ··· Storage means 34 ··· Calculation means 35 ··· Determining means 36 ··· Display drive control unit 37 · ... Display unit

Claims (1)

(57) [Claims] 1. A semiconductor device having a resistive film type structure and
The voltage value output by the pressing force
And a tablet that detects input by
Pen for inputting handwritten information to a computer and inputting the handwritten information
Display that displays the trajectory of the information at the coordinate position where is detected
And a drive signal for driving the display unit
In a handwriting input device having a display drive control unit,
The pen is provided with a pressure sensor that detects pen pressure and
Tab set when the tablet is used for the first time
The average of the pressure values at multiple coordinate positions on the
The reference pen pressure value is stored in advance, and
Stores the output value of the pressure sensor when a force is detected
Storage means, and the pressure when handwritten information is input
Performs a calculation to subtract the reference pen pressure value from the sensor output value
Calculation means and line thickness to be output according to the calculation result
Is determined, and the determined information is sent to the display control drive unit.
Supply means, and the above table
The indicating drive control unit adds the calculation result obtained by the calculation unit to the calculation result.
Display a tablet degradation status based on the
Information on the tablet to display on the display
A handwriting input device characterized by being constituted.