JPH08234910A - Touch panel and transparent digitizer in one - Google Patents

Abstract

PURPOSE: To obtain the touch panel and digitizer in one at low cost by connecting every specific number of electrode lines by the axes of the touch panel and transparent tablet in one which has plural electrode lines to a specific number of analog switches. CONSTITUTION: A carrier signal sending-out circuit 26 oscillates at the same frequency with an input pen, a filter circuit, etc., and sends out a signal of the same frequency and the same level which is π out of phase with the oscillated signal to electrode lines 22 and 24 through analog switches 16 and 17. A CPU 5 supplies a signal which is in phase with a carrier to one side 22 of an output electrode line and the signal which is π out of phase to the other electrode line 24. An input electrode line 23 is sandwiched between two electrodes 22 and 24 and transmits an input signal to a differential amplifier circuit 25. When a body which is artificially grounded such as a finger is put closer to between the input electrode line 23 and output electrodes 22 and 24, the signal supplied to the input electrode line 23 decreases, so the signal of the same frequency and the other phase having an amplitude equal to the difference from the other signal is processed and read in by the CPU 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention detects the position of a tablet touched by the operator's finger or a signal transmission pen,
The present invention relates to a coordinate detection device that outputs the coordinate signal.

[0002]

2. Description of the Related Art When inputting data from a computer or word processor, it is very necessary to ask the operator to make an input such as menu selection, confirmation, character input, position designation, and drawing of a picture. Many. Conventionally, these input items are selected by operating a key on a keyboard, but nowadays, software using a pointing device is becoming mainstream in consideration of a user interface. This shows the relative movement information by the pointing device on the screen with an icon etc., so that the operator moves the operation of this icon like his own hand,
The contents to be operated by looking at the screen are implemented. A mouse is used as a typical example of a pointing device. This mouse has a means for transmitting a two-dimensional movement amount and key information attached to the mouse. By matching the movement direction of this mouse with the movement direction of the icon in software, the operation of the icon and the operator's It is easy for beginners to use because it has the feeling that the icons are moved directly by overlapping the movements.

[0003]

However, although this mouse is also convenient for specifying the position, there is a gap between the icon and the mouse operation when actually drawing lines, planes, etc. on the screen. I couldn't draw as I expected, and the mouse was not suitable for drawing. Therefore, in the present invention, a transparent (transparent) digitizer capable of visually recognizing the display screen is provided on the display surface as a pointing device that can correspond to the display surface in a one-to-one manner so that the position can be more intuitively specified. In addition, in order to pursue the operator's intuition, touch panel mixed pointing that allows direct input with the finger without the digitizer's stylus or pen when high resolution other than position specification, drawing, etc. is not required The device is considered the best input interface.

For example, considering the case where this digitizer and touch panel mixed type device is installed on the screen of a computer, word processor, or electronic blackboard, a confirmation button screen displayed on the screen is touched with a finger as a method of confirming the operation. You will be able to write operator signatures using a stylus or pen. The computer becomes more user-friendly and the operator can use the computer more unconsciously. However, in order to realize this, a touch panel and digitizer are required, and when combining an inexpensive resistive touch panel and electrostatic digitizer, it is necessary to consider the combination due to factors such as signal shielding by a resistive film. Had to choose an expensive device.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the conventional problems, and is a transparent tablet which also serves as a touch panel and has a plurality of electrode lines arranged along the X and Y coordinate axes, and each axis of the transparent tablet. Three analog switches that connect every three electrode lines for each direction, a digitizer that processes the signal induced in the electrode lines as a signal applied from the conductor at the tip of the pen, and the effect of the human body of the operator We propose a transparent digitizer that doubles as a touch panel and detects the position of the touch panel.

[0006]

In the present invention, when operating as a touch panel, the first carrier signal: V0si is applied to one electrode line on one side.
A signal of n (wt) is applied. This first carrier signal has the same frequency as the signal sent by the pen, and can be commonly used by the bandpass filter circuit during the digitizer operation. In addition, a second carrier signal: V0sin (wt +
π) signal is transmitted at the same time. In the input electrode sandwiched between two carrier signal electrodes having different phases, in-phase signals are induced by capacitive coupling from the electrode lines on both sides to the sides in the electrode line longitudinal direction. Since the 1st and 2nd carrier signals are induced and their phases are opposite to each other, the influences from the respective electrode lines are usually canceled out and no signal is generated.

However, when a virtual grounded object such as the operator's finger is located between the input electrode line and the carrier output electrode line, the object becomes a load on the carrier signal of the electrode line near the finger, and the object is also coupled to the object. Signal flows and the current to the input electrode wire stops flowing. At this time, since signals having the same carrier signal but different levels are induced to the input electrode lines, signals of this difference are induced without being canceled. The input signal passes through the amplifier 9 and the bandpass filter 8 in the control circuit 4, noise is eliminated, and AM detection is performed to obtain a DC level voltage and output conversion. When a virtual grounded object such as a finger is present, a larger signal level than usual appears. The signal level that appeared and the position (address) of the three scanned electrode lines
The location where the object exists can be detected by calculating from. By carrying out this method for each of the upper and lower electrode lines, that is, for each of the X direction and the Y direction, a two-dimensional position signal can be generated.

[0008]

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an overall electrical block diagram, FIG. 2 is an overall conceptual diagram, FIG. 3 is a cross-sectional view of essential parts of a tablet, FIG. 4 is an illustration of electrodes of a digitizer, FIG. 5 is an analog switch group circuit diagram, and FIG.
Is a waveform diagram when the digitizer is used, FIG. 7 is an electrode explanatory diagram of the touch panel, and FIG. 8 is a waveform diagram when the touch panel is used.
The touch panel / transparent digitizer 1 includes a transparent tablet 2, an input pen 3, and a control circuit 4, and the control circuit 4 includes a CPU 5, an analog switch group 10, a carrier signal transmission circuit 26, a signal amplification circuit 9, a filter circuit 8,
It is composed of a detection circuit 7 and an A / D conversion circuit 6.

The input pen 3 has a control circuit 4 on the control board 11.
A carrier signal can be transmitted by a signal from the carrier or independently. The transparent tablet 2 uses a glass 12 as a base material for protection from rust and scratches caused by contact with the input pen 3, stylus, fingers, etc., and a plurality of electrode line groups X13 formed by etching parallel ITO films.
And an electrode wire group Y14 orthogonal to this, and XY
Layer 1 in which both electrode wire groups 13 and 14 are transparent and electrically insulated
5 are sandwiched and bonded.

The electrode wire of the electrode wire groups 13 and 14 is about 4 m.
It has a strip shape with m pitch, and the width of one electrode wire is about 2 to 3 mm. This electrode wire is roughly divided into three groups, and each group is connected to a common analog switch. If the electrode wires on the X side are respectively X1,
X2, X3, X4, ..., Xn-1, Xn, Xn
+1 ... As the input / output terminals A1, A2 ,. ． ． , A8 to X1, X4, X respectively
, ..., X (i * 3 + 1) ... (i is an arbitrary integer) are connected every three lines. Similarly, input / output terminals B1, B2, ...
2, X5, X8, ..., X (i * 3 + 2) ... are connected every three lines, and the input / output terminal C of the analog switch C is connected.
1, C2, ..., C8 ... also have X3, X respectively
6, X9, ..., X (i * 3 + 3). This analog switch circuit is shown in FIG. 5, but the analog switches A, B, and C in FIG. 5 are shown as three terminals (channels) for convenience of explanation.

Common terminals (common) Ac, Bc, Cc of the analog switches A, B, C in the first row, to which the respective electrode wires of the X electrode wire group 12 are connected, are four-terminal second-row analog switches D, respectively. , E, and F input / output terminals are connected to common terminals. The first input / output terminal D1 of the analog switch D in the second row is the first input / output terminal G1, H of the analog switch G, H in the fourth row of the third column.
It is connected to 1. The first input / output terminal E1 of the analog switch E in the second row is connected to the second input / output terminals G2, H2 of the four-terminal analog switches G, H in the third row. The first input / output terminal F1 of the analog switch F in the second row is the analog switch G of four terminals in the third row,
The third H input / output terminals G3 and H3 are connected to each other. The fourth output / input terminals G4 and H4 of the analog switches G and H in the third column are connected to GND. The second input / output terminal D2 of the second row analog switches D, E, F,
E2 and F2 are the inverter signals from the oscillator 20
The signal from the oscillator 20 is applied to the input / output terminals D3, E3, and F3 of the oscillator without being converted.

The input / output of the analog switch is bidirectional, and the input / output direction is switched according to the use of digitizer operation / touch panel operation. This switching is performed by inputting a pen signal when the digitizer is used and the electrodes 13 arranged on the tablet 2 when the touch panel is used.
Both carrier signals can be transmitted / received with respect to 14 signals. The CPU 5 can control each electrode line via an analog switch.

Since the control in the X and Y directions is the same for both the digitizer operation and the touch panel operation, the processing method for the X direction will be described below. First, the operation of the digitizer will be described. A signal having a frequency of, for example, about 455 KHz that passes through the bandpass filter 8 of the control circuit 4 can be sent to the input pen 2 from the pen tip. The input pen 3 is the electrode wires 13 and 14 of the tablet 2.
In the vicinity, the input pen 3 and the electrode lines 13 and 14 are capacitively coupled to each other to induce a signal of the same frequency on the electrode lines 13 and 14. The electrode lines 13 and 14 are connected to GND by a resistance of about 1 kΩ to reduce noise and lower the impedance, and the signal induced in the electrode lines 13 and 14 is transmitted to GND and the control board through this resistance. To be done.

In the control circuit 4 of the control board 10, the input signal passes through the analog switches 16 and 17, and then the signal is input to the differential amplifier circuit 25. As a result, the difference between the signals induced in the electrode lines is amplified and the unbalanced state of the signals induced in the electrode lines is detected. Further, noise is removed by the 455 KHz filter 9, and only the signal from the input pen 3 is taken out. The 455 KHz signal corresponds to the input signal level and the AC voltage component in proportion to each other, and is converted to the DC level by the AM detection. The DC level signal is converted into a digital value by the A / D converter 6, and the voltage level is read by the CPU 5, and as a result, the digital value corresponding to the level of the input signal is transmitted to the CPU 5.

Each analog switch connected to the electrode wire groups 13 and 14 is ON / OFF controlled by the CPU 5 so that a signal of an arbitrary electrode wire can be input to the circuit. Further, a differential input is adopted as a measure against noise of the installed display device, and the CPU 5 simultaneously turns on the adjacent electrode lines Xn and Xn + 1 to amplify the difference. (See FIG. 4) As an actual control method, analog switches A and B are selected, and electrode lines X1 (18) and X2 (19) are input. Next, the analog switches B and C are selected to input the electrode lines X2 (18) and X3 (20). In this way, the analog switch is selected so that the signals of the electrode lines adjacent to each other can be sequentially input. A large signal level with respect to the position of the input pen 2 is detected when the pen is present near the input electrode wire (19), and the signal level is low when the pen is far from the input electrode wire (19) or between the input electrode wires. Utilizing this fact, the CPU 5 repeats this operation to calculate the position of the selected electrode wire and the input signal level thereof and detect the position of the digitizer 1 of the pen 3. (FIG. 6
reference)

Next, the operation of the touch panel will be described. The carrier signal transmission circuit 26 of the control circuit 4 of the control board 11 oscillates at the same frequency (about 455 KHz) as the signal oscillation pen as the input pen 2 and the filter circuit, and based on this signal, the same frequency and the same level. Signal whose phase is shifted by π at [V0sin (wt), -V0sin (wt)]
Can be delivered to the electrode wire via an analog switch. The CPU 5 makes a selection such that the analog switch sequentially shifts one input electrode line sandwiched between two output electrode lines. A signal having the same phase as the carrier is applied to one side 22 of the output electrode line, and a signal whose phase is shifted by π is applied to the other electrode line 24. The input electrode wire 23 is the two electrodes 22, 2
It is sandwiched between 4 and the input signal is transmitted to the differential amplifier circuit 25 as in the case of the digitizer. At this time, the other terminal of the differential amplifier circuit 25 is electrically connected to GND using an analog switch. By this method, the input signal is single-ended amplified, and thereafter the same processing as in the case of the digitizer of the band pass filter 8, the AM detection 7, and the A / D conversion 6 is performed.

When a signal whose phase is inverted is sent to the two electrode wires 22 and 24, the input electrode wire 2 sandwiched between the electrodes is sent.
A signal is induced in 3 by capacitive coupling.
Since signals 2 and 24 are out of phase by π and have the same level, the signals from both electrodes are canceled and the signal level becomes 0 level. (Refer to FIG. 8) However, when a pseudo-grounded object such as a finger approaches between the one input electrode line and the output electrode, the output signal is a signal to the human body due to the capacitance of the human body and the like. The signal given to is reduced. That is, when the output balance is lost, a signal having the other phase of the same frequency with the difference from the other signal as the amplitude appears at the input electrode. The frequency of this signal is processed in the same manner as a digitizer, and a digital value can be read by the CPU 5.

As an actual analog switch selection method, V0s is applied to analog switch A so that electrode lines X1 and X3 are used as output electrode lines 22 and 24 and X2 is used as input electrode line 23.
-V0 sin (wt) is applied to in (wt), C so that the analog switch B serves as an input electrode. After A / D conversion, V0sin (wt) is applied to analog switch B and -V0sin (wt) is applied to analog switch A, and analog switch C becomes an input electrode. The signal is read by the CPU 5 while shifting. A large signal level with respect to the position of the human body or the like is detected when a finger or the like is present near the output electrode, and the signal level becomes small when the finger is distant from the output electrode or near the input electrode.

The voltage level distribution has a double peak shape (see FIGS. 6 and 8), and although it is not possible to judge which side of the output electrode is on the basis of the detection level alone, the electrode close to the finger, etc. Since the signal has a low level, a signal having the opposite phase appears as an input signal. Since the input signal can be compared with the phase output before AM detection, calculation can be performed by scanning at two points by discriminating the signal level and phase after detection, and position can be detected at high speed. become. By performing the above processing on the transparent tablet in the X and Y directions, it is possible to operate both the digitizer and the touch panel.

[0020]

Since the present invention has the above-described structure, a common touch panel digitizer can be realized at low cost by using a common circuit for both the digitizer and the touch panel.

[Brief description of drawings] [Description of Drawings]

1 is an overall electrical block diagram

[Figure 2] Conceptual diagram

FIG. 3 is a sectional view of the main part of the tablet.

[Fig. 4] Illustration of electrodes of digitizer

[Figure 5] Analog switch circuit diagram

[Figure 6] Waveform diagram when using the digitizer

FIG. 7 is an illustration of electrodes on a touch panel

[Figure 8] Waveform diagram when using a touch panel

[Explanation of symbols]

 1 Transparent digitizer also used as a touch panel 2 Transparent tablet 3 Input pen 4 Control circuit 5 CPU 6 A / D conversion circuit 7 AM detection circuit 8 Band pass filter-9 Amplifier 10 Analog switch group 11 Substrate 12 Glass 13 X electrode 14 Y electrode 15 Insulation adhesive Material 16 Analog switch 17 Analog switch 18 Electrode wire 19 Electrode wire 20 Electrode wire 21 Oscillator 22 Output electrode wire 23 Input electrode wire 24 Output electrode wire 25 Differential amplification circuit 26 Carrier signal sending circuit

Claims (1)

[Claims] 1. A transparent tablet also serving as a touch panel having a plurality of electrode lines arranged along X and Y coordinate axes, and three analog switches for connecting every three electrode lines in each axial direction of the transparent tablet. And a digitizer that processes a signal induced in the electrode wire as a signal applied from a conductor at the tip of the pen, and a touch panel transparent that detects the position of the touch panel that is detected by the influence of the human body of the operator. Digitizer.