JPH0822358A - Resistive tablet controller - Google Patents

Abstract

(57) [Abstract] [Purpose] An object is to provide a resistive film tablet control device capable of increasing the resolution in a specific region. [Configuration] Button 19 for setting the high precision mode,
A gain adjusting unit 11 for adjusting the amplification factor of the position detection output,
15, amplification units 12 and 16, offset voltage adjustment units 13 and 17 for adjusting offset voltage, and A / D converter 3
The protection limiters 14 and 18 and the buzzer 20 that outputs a warning sound when a region other than the specific region is input are configured. When the high-precision mode is set, the output side for position detection is provided with the gain adjustment units 11 and 15 and the offset voltage. After adjusting by the adjusting units 13 and 17 and amplifying by the amplifying units 12 and 16, the limiters 14 and 1
8 to connect to the A / D converter 3 and raise the voltage applied to the specific area from the standard mode to increase the resolution of the specific area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistive film tablet control device used in information terminal devices and the like.

[0002]

2. Description of the Related Art A conventional resistive film tablet controller will be described. FIG. 4 is a configuration diagram of a conventional resistive film tablet control device, and FIG. 5 is a state table of SWs (switches) of the resistive film tablet control device. In FIG. 4, reference numeral 1 is a resistive film tablet (hereinafter abbreviated as a tablet), the XH terminal from one of the upper electrode side is on the + side of the power source 2 via SW5,
The XL terminal from the other side is the GND of the power supply 2 via SW7.
Side and the contact A side of the switching SW 9 are connected to the A / D converter 3. The YH terminal from one side of the lower electrode of the tablet 1 is on the + side of the power source 2 via SW6, and the YL terminal from the other side is the G side of the power source 2 via SW8.
It is connected to the A / D converter 3 via the ND side and the contact B side of the switching SW 9.

The A / D converter 3 converts the analog voltage (divided voltage) value from the tablet 1 into a digital value, using the voltage on the + side of the power source 2 as a reference voltage. The control section 4 performs position detection and the like based on the control of the SW5 to SW8 groups and the A / D converter 3 and the output of the A / D converter 3. In addition, when measuring the X side and the Y side, the control unit 4 controls according to the state table shown in FIG.

[0004]

In the case of the conventional example, the voltage applied between the upper electrodes and the lower electrode of the tablet 1 is equal to the voltage between the power supply 2 and its value is the maximum A / D of the A / D converter 3. Determined from the input width. The position detection method of the tablet 1 is obtained from the divided voltage between the electrodes, and the resolution of the tablet 1 is determined by the number of bits of the A / D converter 3. Therefore, in the case of the above-mentioned conventional example, when the area of the tablet 1 becomes large, the minimum detection (1LSB) voltage does not change, but the minimum detection (1LSB) distance becomes long and there is a problem that the resolution deteriorates. Therefore, in order to improve this problem, the number of bits of the A / D converter was increased, but the cost was significantly increased, and even if the number of bits was increased, the S / Due to the deterioration of N, the size of the tablet was limited.

In recent years, the number of information terminal devices that require high resolution and high precision such as character recognition and software keyboards has increased, but most of them require high precision over the entire area of the tablet. Instead, the characters are recognized in a specific character frame. Since high resolution and high accuracy are required for those specific areas,
Expensive electromagnetic induction tablets and the like are used, and low-cost resistive film tablets are limited to small ones.

Therefore, an object of the present invention is to provide a resistive film tablet control device capable of increasing the resolution in a specific area.

[0007]

In order to solve the above problems, the present invention provides a switch group for connecting upper and lower electrodes of a tablet between power sources and an input side of an A / D converter to the X side or the Y side of the tablet. Switch for switching to position detection output
An amplification section for amplifying the X-side or Y-side position detection output of the tablet; a gain adjustment section for adjusting the gain of the amplification section; an offset voltage adjustment section for adjusting the offset voltage for the amplification section; A limiter for clipping the subsequent output at the maximum input voltage of the A / D converter, a manipulator for setting the high-accuracy mode, an alarm element, a control unit, and a storage unit are configured, and in the standard mode, the X side of the tablet. Alternatively, the output for position detection on the Y side is directly connected to the input of the A / D converter, and position detection is performed according to the standard position correction formula stored in the storage unit. When the mode is set, the gain adjuster is controlled and amplified so that the gain becomes a predetermined amplification factor for each setting location, and the offset voltage is also shifted by the offset voltage adjuster. , Through the limiter and connected to the A / D converter to increase the voltage width applied to a specific area requiring high accuracy to increase the resolution of the specific area, and position correction for high accuracy mode held in the storage unit. The position detection is performed according to the formula, and when an input other than the specific area is erroneously input in the high precision mode, the input is ignored and an alarm element notifies that effect.

[0008]

With the above construction, the resolution can be increased only in a specific area where high precision such as character recognition is required by the same A / D converter as in the standard mode. Further, by adjusting the offset voltage, it is possible to deal with a specific region where high accuracy is required.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a resistive film tablet control device according to an embodiment of the present invention, and FIG. 2 is a SW state table of the resistive film tablet control device. The same parts as those in the conventional example shown in FIG. At the time of Y side measurement in the standard mode, the XL terminal of the tablet 1 is connected to the A / D converter 3 through the contact A side of the double switching SW 10-1 and the contact A side of the switching SW 9. On the other hand, at the time of Y side measurement in the high precision mode, the gain adjustment unit 11 and the offset voltage adjustment unit 13 adjust the amplification factor and the offset voltage of the XL terminal of the tablet 1, the amplification unit 12 performs amplification, and the limiter 1
4 through the contact B side of the switching SW10-1 of two stations and the switching S
The contact A side of W9 is connected to the A / D converter 3.

Similarly, the YL terminal of the tablet 1 also passes through the contact A side of the double switch SW10-2 and the contact A side of the switch SW9 during the X mode measurement in the standard mode, and the A / D converter 3 is also provided.
Connected to. Further, at the time of the X side measurement in the high precision mode, the YL terminal of the tablet 1 is adjusted in gain and offset voltage by the gain adjusting unit 15 and the offset voltage adjusting unit 17, amplified by the amplifying unit 16, and then passed through the limiter 18 to be connected twice. Switching S
A through the contact B side of W10-2 and the contact A side of the switching SW9
Connect to the / D converter 3.

The button 19 is for setting the high-accuracy mode, and the buzzer 20 is for issuing a warning sound when an input from outside the specific area is input when the high-accuracy mode is set. The storage unit 21 holds the amplification factor and the position correction formula in the standard mode and the high precision mode.

FIG. 3 is an explanatory diagram of the output voltage of the tablet of the resistive film tablet controller according to the embodiment of the present invention. In FIG. 3, 30 is a specific area, and the left side of the tablet 1 is XL.
The terminal side and the right side are the XH terminal side. Here, only the measurement state on the X side will be described. Where tablet 1
The description will be made assuming that the horizontal length (XL terminal−XH terminal) is L, the power supply voltage is V, and the A / D converter 3 is n bits.
The A side of the specific area 30 is (1/5) L and the B side is (2/5)
In the L position, the A / D input in the standard mode is (1/5) V on the A side and (2/5) V on the B side. Therefore, at this time, the distance of (1/5) L of the specific region width is (2 ^ n) ×
It can be divided by (1/5).

Next, a case will be described in which, after the specific area 30 is designated, the high precision mode is set by the button 19 and is amplified three times by the amplifying section 12. The voltage at the amplifier 12 is (1/5) × 3V on the A side and (2/5) × 3V on the B side.
At this time, the outside of the specific region is similarly amplified and the XH terminal portion becomes 3V.

In the next offset voltage adjusting section 13, the offset voltage is shifted from 0V to-(2/5) V so that the A side of the voltage of the specific region 30 is (1/5).
Set the VH and B side to (4/5) V and the XH terminal part to (3-2 /
5) Shift to V. Here, the offset voltage is adjusted so that the voltage width of the specific region 30 can be amplified wherever the specific region 30 is. The next limiter 14 clips the portions of 0 V or less and V or more, and uses them as the inputs of the A / D converter 3. This is to prevent the A / D converter 3 from being destroyed when a mode other than the high precision mode is erroneously input. From the above, in the high-precision mode, the same (1/5) L distance as in the standard mode is set to (2
^ N) × (3/5) can be divided, and the standard mode is 3
Double resolution will be obtained.

Here, it is necessary to select the amplification factor of the amplification section 12 so that the width of the specific region 30 becomes equal to or less than the maximum input voltage of the A / D converter 3. Further, in the high precision mode, it is necessary to detect the position based on the high precision mode position correction formula held in the storage unit 21. This is the specific area 30
This is to prevent the enlarged display. Specific area 30
Other than that, the data is ignored as an erroneous input, and the buzzer 20 issues a warning sound to give a warning.

[0016]

As described above, according to the present invention, it is possible to realize a resistive film tablet capable of achieving high precision only in a specific region without using an expensive multi-bit A / D converter.
Further, the specific region can be set anywhere by adjusting the amplification factor and the offset voltage. Furthermore, by utilizing the above-mentioned characteristics, it becomes possible to apply a low-cost resistive film tablet that could not be used for a large-sized information terminal in the past.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a resistive film tablet controller according to an embodiment of the present invention.

FIG. 2 is a diagram showing a SW state table of the resistive film tablet controller according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of the output voltage of the tablet of the resistive film tablet controller according to the embodiment of the present invention.

FIG. 4 is a block diagram of a conventional resistive film tablet control device.

FIG. 5 is a diagram showing a SW state table of a conventional resistive film tablet control device.

[Explanation of symbols]

 1 Resistive film tablet 3 A / D converter 4 Control section 5, 6, 7, 8 SW 9,10 Switching SW 11, 15 Gain adjustment section 12, 16 Amplification section 13, 17 Offset voltage adjustment section 14, 18 Limiter 19 Button ( Operator) 20 Buzzer (alarm element) 21 Storage section 30 Specific area

Claims (1)

[Claims] 1. A switch group for connecting upper and lower electrodes of a resistive film tablet between power supplies, and a changeover switch for switching an input side of an A / D converter to an X-side or Y-side position detecting output of the resistive film tablet. An amplification unit that amplifies the X-side or Y-side position detection output of the resistive film tablet, a gain adjustment unit that adjusts the gain of the amplification unit, and an offset voltage adjustment unit that adjusts the offset voltage for the amplification unit. ,
The resistive film tablet is provided with a limiter for clipping the output after amplification at the maximum input voltage of the A / D converter, a manipulator for setting a high precision mode, an alarm element, a control section, and a storage section, and in the standard mode. X-side or Y-side position detection output is directly connected to the A / D converter input, and position detection is performed according to the standard position correction formula held in the storage unit, while setting a specific location, When the high-accuracy mode is set by the operator, the gain adjusting unit is controlled and amplified so that the amplification factor is predetermined for each setting location, and the offset voltage is also shifted by the offset voltage adjusting unit. After that, the voltage is applied to the A / D converter through the limiter to increase the voltage width applied to a specific area requiring high accuracy to increase the resolution of the specific area. Performs position detection in accordance with the high precision mode for position correction equation stored in the serial storage unit,
A resistor film tablet control device characterized in that, when an input other than a specific area is erroneously input in the high-accuracy mode, the input is ignored and the alarm element notifies that effect.