JPH0764701A - Display integrated tablet - Google Patents

Abstract

PURPOSE:To shorten a display stop period in one screen display period by extracting detection signals obtained by electrostatic coupling as coordinate detection signals of X and Y through band pass filters corresponding to the respective frequencies. CONSTITUTION:High frequency signals f1, f2 generated from X and Y electrode high frequency power source parts 6, 4 are superposed at every scanning voltage, and impressed to an electrode from X and Y scanning drivers 5, 3. Subsequently, a coordinate detection signals D inputted from a stylus pen 8 is supplied to X and Y coordinate band pass filters 9, 10. Next, an X scanning voltage passes through the X coordinate band pass filter 9, by which a signal component of the high frequency signal f1 superposed to this signal comes to be extracted, and this signal is outputted as an X coordinate detection signal to a coordinate detection controller 11. Also, in the Y coordinate band pass filter 10, a signal component of the high frequency signal f21 superposed to a V scanning voltage is extracted, and outputted as a Y coordinate detection signal Dy to the coordinate detection controller 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display-integrated tablet in which a display and a tablet capable of inputting coordinates are integrated.

[0002]

2. Description of the Related Art FIG. 6 shows an example of the structure of a display-integrated tablet 30 which has been conventionally used.
Reference numeral 31 is a matrix tablet (hereinafter, simply referred to as a tablet), and in this case, a thin film EL (electric luminescence) matrix tablet is used. The tablet 31 is provided with X electrodes (x _{1 to} x _m ) arranged in the column direction for horizontal scanning and Y electrodes (y _{1 to} y _n ) arranged in the row direction for vertical scanning arranged in a matrix. ing.

Each X electrode (x _{1 to} x _m ) is connected to an X scan driver 32, and the X scan driver 32 controls each X electrode (x _{1 to} x _m ) at a predetermined timing under the control of a driver controller 34. A scanning voltage is applied to the scanning voltage. The Y electrode (y ₁ ~y _n) is connected to the Y scan driver 33, relative to the Y electrodes at a predetermined timing under the control of the Y scan driver 33 also the driver controller 34 (y ₁ ~y _n) Apply a scanning voltage. Reference numeral 35 denotes a CPU for performing image display scanning control and detecting an input coordinate designated by a stylus pen from a peak detection signal at a predetermined timing as described later.

Reference numeral 36 denotes a stylus pen for inputting coordinates by the capacitive coupling method by bringing the detection end portion (pen tip) of the tip into contact with the tablet. Also,
37 is an amplifier for amplifying the coordinate detection signal from the stylus pen 36, and 38 is peak detection for the coordinate detection signal output from the stylus pen 36 via the amplifier 37, and the detected coordinate position of the peak point. CP
The peak detection part supplied to U35 is shown.

Next, the display operation and coordinate input operation in the display-integrated tablet 30 will be described with reference to FIGS. 7 and 8. FIG. 7 shows the X scan driver 3
2 and Y tablets 1 executed by the scanning driver 33 X, shows a Y scan timing waveforms of each electrode _{(x 1 ~x m) (y} 1 ~y n). As shown in this figure, assuming that the period for displaying one screen and the period for detecting the pen input position correspond to one frame (or one field) period, and one screen display period, the display operation is actually performed during this period. Is displayed, and a Y-coordinate detection period and an X-coordinate detection period for responding to coordinate input.

[0006] In the display period, Y scan driver 33, for each Y electrode (y ₁ ~y _n), by applying a sequential scanning voltage as shown in FIG. 7 (a) ~ (c) , the vertical scanning To execute. That is, voltage is applied line by line from the Y electrodes y ₁ to y _n in accordance with the vertical / horizontal synchronization signal. On the other hand, the X scan driver 32 uses each X electrode (x _{1 to} x
relative to _m), based on the display data supplied from the driver controller 34, FIG. 7 (d) ~ (f) are shown as Y electrodes y ₁ ~y _n each electrode in each scanning period (x ₁ ~
x _m ) is applied with a voltage. That is, a voltage is applied to the X electrode corresponding to the display pixel on a certain Y electrode (horizontal line). Therefore, during each scanning of the Y electrodes y _{1 to} y _n , the pixels intersecting the X electrodes to which the voltage is applied emit the fluorescent substance by the electric field by the X electrodes and the Y electrodes, and the display operation is performed. . In addition, FIG.
(L) shows the X electrode by expanding the scanning period of the Y electrodes y ₁ and y _2.
It is an enlarged view of the scanning timing from the electrode x ₁ to the X electrode x _m .

When such a display period ends, the next Y
The operation as the coordinate detection period is performed. The Y-coordinate detection period and the subsequent X-coordinate detection period are periods for detecting coordinate input due to contact of the stylus pen 36 with the tablet 31. First, in the Y coordinate detection period, only the Y scan driver 33 sequentially applies the detection voltage to the Y electrodes y _{1 to} y _{n as shown in} FIGS. 7A to 7C. Therefore, the stylus pen 3 is placed at a certain point on the tablet 31.
When the pen tip 6 is in contact with the stylus pen 36, capacitance coupling is performed between the Y electrode and the stylus pen 36 that are close to the position, and the stylus pen 36 outputs a voltage output as a coordinate detection signal. . Further, during the X coordinate detection period, only the X scan driver 32 sequentially applies the detection voltage to the X electrodes x _{1 to} x _{m as shown in} FIGS. 7D to 7F. Therefore, when the pen tip of the stylus pen 36 is in contact with a certain point on the tablet 31, capacitive coupling is performed between the X electrode and the stylus pen 36 which are close to the position, and the stylus pen 36 is touched. A voltage output as a coordinate detection signal is obtained from 36.

In FIG. 8, the horizontal axis indicates the position in the X or Y direction, and the vertical axis indicates the capacitance. In reality, the capacitance distribution is relative to the contact position of the stylus pen 36 in FIG. It is shown as a curved line, and therefore some Y electrode (or X
Even during the scanning period of the Y electrode (or X electrode) adjacent to the electrode), the stylus pen 36 produces a voltage output along this curve. Therefore, for example, at the time of scanning a certain Y electrode, the coordinate detection signal shown in FIG. 8 is transmitted from the stylus pen 36 via the amplifier 37 to the peak detection circuit 38.
Then, the peak detection circuit 38 detects the peak point position of the coordinate detection signal by, for example, a comparator having a certain voltage as a reference, and supplies the peak point position signal to the CPU 35 at that time. And the CPU 35
Then, by discriminating the Y electrode being scanned in the period corresponding to the timing when the peak point position is supplied, the Y electrode at the position where the stylus pen 36 is in contact, that is, the Y coordinate can be discriminated. . The same applies to X-coordinate detection. That is, the X-coordinate detection period and sequentially supplied to the scan voltage to the X electrodes x ₁ ~x _m for X coordinate detection, the peak point position signal to obtain a detection voltage as shown in FIG 8 CPU 35 Supply to.

As described above, the Y coordinate as the input position is detected during the Y coordinate detection period, and the X coordinate as the input position is detected during the X coordinate detection period. The coordinates will be input.

[0010]

By the way, in the display-integrated type tablet having such a structure, it is necessary to perform image display and coordinate detection by the same tablet.
As shown in FIG. 7, the display period for one screen is divided into the actual display period and the X and Y coordinate detection period. Further, during the detection period, since a pulsed scanning voltage of several tens to several hundreds of volts is sequentially applied to the X electrode and the Y electrode, the pulse width of the scanning pulse requires several μs per electrode. Therefore, in the one-screen display period, the time required for detection, that is, the period corresponding to the display stop is considerably long, and the actual display period is also shortened. Normally, in such a display, the one-screen display period is 1/60 second (about 16.7 ms) to 1/70 second (about 1).
4.2 ms), for example, 60 Y electrodes, X
Even if scanning is performed at the time of detection with a pulse width of 5 μs using a high-speed driver with a resolution of 80 electrodes, the Y, X coordinate detection period is (60 × 5) + (80 × 5) =
Since 700 μs (0.7 ms) is required, the occupation ratio of the time required to detect the X coordinate and the Y coordinate within one screen display period is considerably large. As described above, there is a problem that the display becomes dark if the actual display period is short in the one-screen display period. When the stylus pen 36 is used for character recognition rather than simple pointing, the stylus pen 36 moves on the tablet at an appropriate speed. Therefore, at least 1 is required for coordinate detection from the viewpoint of accuracy. It is required to be performed every / 120 (about 8.3 ms) seconds. Therefore, in order to realize this detection speed in the coordinate detection method shown in FIG. 7 and, for example, when the number of times of coordinate detection within one screen display period is performed a plurality of times or more, when the coordinate width is determined by the relationship between the pulse width and the number of scanning electrodes. Since the detection time cannot be shortened, the display period is shortened as a result, and the displayed image becomes darker, which is not suitable for actual use.

[0011]

Therefore, in order to solve the above-mentioned problems, the present invention solves the above problems by using a plurality of X electrodes for scanning and Y electrodes.
A tablet having electrodes arranged in a matrix and having a display surface, an X electrode drive unit capable of driving each of these X electrodes at a predetermined timing, and a Y electrode drive capable of driving each Y electrode at a predetermined timing. Part, X,
A detection conductor to which a coordinate detection signal can be input by positioning the Y electrode on the driven tablet;
X based on the coordinate detection signal supplied from this detection conductor
By providing a coordinate detection unit capable of detecting coordinates and Y coordinates, in a display-integrated tablet capable of displaying an image and inputting coordinates, a high frequency signal of a predetermined frequency is generated to scan the X electrode drive unit. A first high-frequency generator that outputs a high-frequency signal and a second high-frequency generator that generates a high-frequency signal having a predetermined frequency different from that of the first high-frequency generator and outputs the high-frequency signal to the Y electrode drive unit are provided. To do. Further, a first bandpass filter for extracting a frequency corresponding to the first high-frequency generation unit from the coordinate detection signal input from the detection conductor and outputting it to the coordinate detection unit, and coordinates input from the detection conductor. A second band-pass filter that extracts the frequency corresponding to the second high frequency generator from the detection signal and outputs the frequency to the coordinate detector is provided. Then, in the same coordinate detection period in which the coordinate detection is performed, the X electrode drive unit performs scanning while applying the high frequency signal generated by the first high frequency generation unit to the X electrode, and the Y electrode drive unit The scanning is performed while applying the high frequency signal generated by the second high frequency generator to the Y electrode.

[0012]

According to the above structure, since the scanning voltage used for coordinate detection has different high frequency components on the X electrode side and the Y electrode side, these are input to the detection conductor (stylus pen) as detection signals. Also, it is possible to separate by passing through the band pass filter corresponding to each high frequency. Therefore, both the X and Y electrodes can be simultaneously scanned in the same coordinate detection period, which shortens the display stop period in one screen display period and lengthens the actual image display period. It becomes possible.

[0013]

EXAMPLES Examples of the present invention will be described below.
As the display-integrated type tablet in this embodiment, a display using a field emission cathode is used. First, this field emission type display will be described.

The applied electric field on the surface of the metal or semiconductor is set to 10 ⁹
When it is set to about [V / m], electrons pass through the barrier due to the tunnel effect, and electrons are emitted in vacuum even at room temperature. This is called field emission, and a cathode that emits electrons according to such a principle is called a field emission cathode. In recent years, by making full use of semiconductor processing technology, micron-sized field emission cathodes (hereinafter,
It is possible to make a surface emission type FEC consisting of an array (called FEC).

FIGS. 4 (a) and 4 (b) show an example of the FEC called Spindt type. (A) of this figure is a perspective view of an FEC created using a semiconductor processing technique, and (b) is a view showing a cross section of the FEC taken along the line AA shown in (a). In these figures, a cathode electrode formed of a metal such as aluminum is provided on a substrate, and a cone-shaped emitter is formed on the cathode electrode. A gate electrode is further provided on the cathode electrode via a SiO ₂ film so that the emitter is located in the opening formed in the gate electrode. That is, the tip of the cone-shaped emitter faces through the hole formed in the gate electrode.

The pitch between the cone-shaped emitters is 10
Since it can be set to a micron or less, tens of thousands to tens
Ten thousand FECs can be provided on one substrate. Further, since the distance between the gate electrode and the tip of the cone of the emitter can be made submicron, by applying a voltage of only several tens of volts between the gate electrode and the cathode electrode, electrons are emitted from the emitter by field emission. You can do it.

Since this FEC has a planar shape as shown in the figure, it can be used as a surface emission type field emission cathode, and such a surface emission type field emission cathode is used. Thus, a field emission display device (hereinafter referred to as FED (Field Emission Display)) can be constructed. Then, for example, if this FED and an input means for detecting coordinates such as a stylus pen are combined,
Since it is also possible to perform coordinate detection by utilizing electrostatic coupling between the D electrode and the detection conductor, a display-integrated tablet can be constructed by this FED.

FIG. 5 is a perspective view showing the structure of such an FED, and in this case, it is the same as that used as a tablet in this embodiment. In this FED, 21 indicates a first substrate, and y ₁ to y _n formed in stripes on the first substrate 1 indicate cathode electrodes as Y electrodes. The cathode electrodes y _{1 to} y
Cathode terminals C1 to Cn, to which a drive pulse described later is supplied, are connected to _n .

Further, x ₁ ~x _m represents the gate electrode of the X electrode, on the cathode electrode y ₁ ~y _n via an insulator, in stripes as perpendicular to the cathode electrodes y ₁ ~y _n Has been formed. And the gate electrodes x _{1 to} x _m
Drive gates are supplied to the gate terminals G1 to Gm
Are connected. In this way, the cathode electrode (Y electrode) y ₁
To y _n and the gate electrodes (X electrodes) x _{1 to} x _m are arranged in a matrix. Reference numeral 22 is a hole formed in the gate electrodes x _{1 to} x _m , for emitting a field emission electron from the cone-shaped emitter (see FIG. 4) formed on the cathode electrodes y _{1 to} y _n . Is formed.

Reference numeral 23 denotes a second substrate which is arranged so as to face the first substrate 21. The anodes 24, 24 ... Formed on the second substrate 23 are arranged in stripes corresponding to the positions of the gate electrodes x _{1 to} x _m as shown in the figure. An anode lead electrode A is connected to each anode electrode 24. 25 is a phosphor, which is provided on the surface of the anode electrode 24 facing the gate electrodes x _{1 to} x _m ,
Excited by the collision of electrons. Then, each of the above-mentioned parts is enclosed in a hermetically sealed container, and each of the above-mentioned terminals is pulled out to form a display-integrated tablet.

Therefore, an example of a driving method for displaying an image by the FED 1 will be schematically described. The anode electrode 24 formed on the second substrate 23 is supplied with a substantially constant anode voltage by the anode extraction electrode A. On the other hand, cathode electrodes (Y electrodes) y _{1 to} y
_The scanning pulse is supplied to each of the cathode terminals C1 to Cn to scan _n, so that each stripe-shaped cathode electrode is sequentially selected and driven.

Therefore, the cathode terminals C1 to Cn are sequentially scanned while a positive anode voltage is applied to the anode extraction electrode A to drive the anode electrode 24. At this time, a voltage according to the data of the image signal is applied to the gate terminals G1 to Gm according to the scanning timing. As a result, the pixel of the phosphor 25 provided on the anode electrode 24 is excited by the electrons emitted from the scanned cathode electrodes y _{1 to} y _n , and this pixel is gate terminal G
The light emission is controlled according to the voltage applied to 1 to Gm, and thus one screen of the image is displayed.

FIG. 1 is a circuit diagram showing the structure of a display-integrated tablet which employs the FED as a tablet. In this figure, reference numeral 1 is a tablet, and an FED having the same configuration as that shown in FIG. 5 is used, and the description of the structure of the tablet 1 is omitted. Although the anode electrode 24 (and the phosphor 25) and the anode lead-out electrode A are not shown in this figure, the anode electrode 24 is supposed to be arranged on the gate electrodes x _{1 to} x _m. A is assumed to be connected to an anode driver 10 described later. Also for convenience, hereinafter cathode y ₁ ~y _n is Y electrode, the gate electrode x ₁ ~x _m is to unify the names as X electrodes.

A display / coordinate detection signal controller 2 outputs control signals Cs1 and Cs3 corresponding to display data to control the application timing of the scanning voltage of the Y scanning driver 3 during the image display period as described later. At the same time, the application timing of the voltage according to the image data of the X scan driver 5 is controlled. Further, in this case, the control signal Cs5 is output to control the voltage application operation of the anode driver 10. Further, during the detection period, the control signals Cs2 and Cs4 are output to operate the Y electrode high frequency generating section 4 and the X electrode high frequency generating section 6, and to the X and Y electrodes via the X and Y scanning drivers 5 and 3, respectively. Control is performed so that the coordinate detection signal is scanned at a predetermined timing.

Reference numeral 3 denotes a Y scan driver, which is Y as shown in the figure.
A cathode terminal C1~C provided electrode (y ₁ ~y _n)
n are connected. That is, the Y scan driver 3 outputs Y at a predetermined timing according to the output signal of the display / coordinate detection signal controller 2 or the Y electrode high frequency power supply unit 4.
The electrode (y ₁ ~y _n) and outputs a scanning signal for image display or coordinate detection. Reference numeral 4 denotes a Y electrode high frequency generator, which generates a high frequency signal having a predetermined frequency under the control of the display / coordinate detection signal controller 2 during a coordinate detection period described later. The Y electrode high frequency power supply unit 4
The high-frequency signal generated in step 2 has a frequency different from that of the high-frequency signal generated in the X-electrode high-frequency power supply section 6 described below. Then, the high-frequency signal generated here is supplied to the Y scan driver 3 as a scan signal for the Y electrode when the Y coordinate is detected.

Reference numeral 5 denotes an X scan driver, which is an X electrode (x ₁
To x _n ) are connected to the gate terminals G1 to Gm, and the X scan driver 5 operates according to a signal from the display / coordinate detection signal controller 2 or the X electrode high frequency power supply unit 6 at a predetermined timing. Scan signals for image display or coordinate detection are output to x _{1 to} x _n ). Reference numeral 6 denotes an X electrode high frequency power supply unit, which generates a high frequency signal of a predetermined frequency under the control of the display / coordinate detection signal controller 2 during the coordinate detection period, and uses this as an X coordinate scanning signal for X coordinate detection. It is supplied to the scan driver 5. In addition,
As described above, the high frequency signal generated by the X electrode high frequency power supply unit 6 has a frequency different from that of the high frequency signal generated by the Y electrode high frequency power supply unit 4.

Reference numeral 7 denotes an anode driver, which is actually connected to the anode extraction electrode A of the tablet 1.
Then, according to the control of the display / coordinate detection signal controller 2, a positive anode voltage for driving the anode electrode 24 is output.

Reference numeral 8 is a stylus pen, and a tablet 1
The voltage generated between the pen tip and the X and Y electrodes due to capacitive coupling is input by bringing the detection end (pen tip) of the tip into contact with the surface of the, and this is applied to the X coordinate band in the subsequent stage. The coordinate detection signal D is output to the pass filter 9 and the Y coordinate band pass filter 10. Reference numeral 9 denotes an X coordinate band pass filter, which has a characteristic of passing a frequency band of a signal generated by the X electrode high frequency power supply unit 6. This allows
A signal obtained by capacitive coupling on the X electrode side is extracted from the coordinate detection signal supplied from the stylus pen 8 and output as an X coordinate detection signal Dx. Reference numeral 10 denotes a Y-coordinate bandpass filter, which has a characteristic of passing a frequency band of a signal generated by the Y-electrode high-frequency power supply unit 4.
As a result, a signal obtained by capacitive coupling on the Y electrode side is extracted from the coordinate detection signal supplied from the stylus pen 8 and output as the Y coordinate detection signal Dy.
Reference numeral 11 denotes a coordinate detection controller, and in this case, coordinates input based on the X coordinate detection signal Dx and the Y coordinate detection signal Dy input from the X coordinate bandpass filter 9 and the Y coordinate bandpass filter 10, respectively. Is detected and this coordinate data is output to a required circuit. Then, predetermined processing is performed based on the output coordinate data.

Next, referring to FIG. 2, the operation of image display and coordinate detection of the display-integrated type tablet having the above-mentioned configuration will be described. Figure 2 is a timing chart showing the drive timing of X in one screen display period of a display-integrated type tablet of the present embodiment, Y each electrode _{(x 1 ~x m) (y} 1 ~y n). In this embodiment,
As shown in this figure, the one-screen display period for forming one screen is divided into a display period for actually performing a display operation and a coordinate detection period for responding to coordinate input.
As the coordinate detection period, the scanning periods of the X electrode and the Y electrode are not set in a time-divided manner, but the scanning of the X electrode and the Y electrode is simultaneously performed in the same coordinate detection period.

First, in the display period, the display / coordinate detection signal controller 2 controls the Y scan driver 3 and the X scan driver 5 based on the control signal C based on the display data.
s1 and Cs3 are output, and a control signal Cs is output so that the anode driver 7 can drive the anode electrode 24.
5 is output. On the other hand, control signals Cs2 and Cs4
Is not output. Therefore, the Y electrode high frequency power supply unit 4 and the X electrode high frequency power supply unit 6 do not operate. Then, Y scanning driver 5 by the control of the display / coordinate detection signal controller 2, for each Y electrode (y ₁ ~y _n), a vertical / horizontal synchronizing signal as shown in FIG. 2 (a) ~ (c) Then, the scanning voltage is sequentially applied to perform vertical scanning line by line. At this time, the X scan driver 5 performs the operation shown in FIG. 2 based on the display data supplied from the display / coordinate detection signal controller 2 to each X electrode (x _{1 to} x _m ).
(D) in each scan period of the Y electrodes y ₁ ~y _n as shown in ~ (f) to the electrodes (x ₁ ~x _m) will perform the voltage application. That is, the scanning method for image display in this embodiment may be the same as that shown in FIGS. At this time, since a voltage is applied to the anode electrode 24 by the anode driver 7 as shown in FIG. 2G, it intersects with the X electrode to which the voltage is applied during each scanning of the Y electrodes y _{1 to} y _n. Electrons are emitted from the emitter at the position where the electrons are emitted and are drawn into the anode electrode 24. At this time, the phosphor 25 formed on the anode electrode 24 emits light by collision of electrons, and the display operation is performed in this manner.

As described above, when the Y-electrode y _n is finally scanned and the display period ends, the operation is switched to the coordinate detection period. In this coordinate detection period, the display / coordinate detection signal controller 2 first stops the output of the control signals Cs1, Cs3, and Cs5. As a result, the X and Y scan drivers 5 and 3 do not control the scan based on the image data, and the anode electrode 2 as shown in FIG.
Since no voltage is applied to No. 4 as well, the image display operation is stopped. With this, display /
The coordinate detection signal controller 2 sends a control signal C to the Y electrode high frequency power supply unit 4 and the X electrode high frequency power supply unit 6.
The state is switched to output s2 and Cs4. This allows
The high frequency signals f ₁ and f ₂ respectively generated by the X electrode high frequency power supply unit 6 and the Y electrode high frequency power supply unit 4 are, for example, as shown in FIG.
As shown in (a) to (c) in an enlarged manner, they are superimposed on each scanning voltage and applied to the electrodes from the X scan driver 5 and the Y scan driver 3 at predetermined scan timings. Incidentally, when the high-frequency frequency of X scanning side as described above and f _1, the relationship between the RF frequency f ₂ of the Y scanning side is to the f _1> f ₂ or f ₁ <f _2.

In the coordinate detection period, the Y scan driver 3 operates on the Y electrodes y ₁ to y as shown in FIGS. 2 (a) to 2 (c).
A high frequency detection scanning signal is sequentially applied to y _{n at} a predetermined timing. In the same coordinate detection period, X
In the scan driver 5, as shown in FIGS. 2D to 2F, a high frequency detection scan signal having a frequency different from that on the Y scan side is sequentially applied to each X electrode x _{1 to} x _{m at} a predetermined timing. . Depending on conditions such as a difference in the number of electrodes on the X side and the Y side, the time when the scanning on the X electrode side and the Y electrode side ends may differ in the detection period, but the X electrode side is faster than the Y electrode. In the case where the timing is such that the scanning ends, for example, when the X electrode side scans up to the X electrode x _m , the voltage application operation to the X electrode side is stopped until the scanning of the Y electrode ends. It is also conceivable to operate the display / coordinate detection signal controller 2 so as to operate.

When the pen tip of the stylus pen 8 is in contact with a certain point on the tablet 1 during this coordinate detection period, the X electrode corresponding to that position and the stylus pen 8 are in contact.
And between the Y electrode and the stylus pen 8, capacitive coupling is performed, and the voltage generated at this time is the stylus pen 8
Is input as the coordinate detection signal D. That is, in this embodiment, the coordinate detection signal D is a signal in which a signal component obtained by capacitive coupling on the X electrode side and a signal component obtained by capacitive coupling on the Y electrode side are mixed.

The coordinate detection signal D input from the stylus pen 8 in this manner is used for the X-coordinate bandpass filter 9 and the Y-coordinate bandpass filter 1 connected in the subsequent stage.
Supplied to zero. Then, the X scanning voltage passes through the X coordinate band pass filter 9, whereby the signal component of the high frequency signal f ₁ superimposed on this signal is extracted,
This signal is output to the coordinate detection controller 11 as the X coordinate detection signal Dx. The Y-coordinate bandpass filter 10 extracts the signal component of the high-frequency signal f ₂ superimposed on the Y-scanning voltage and outputs it as the Y-coordinate detection signal Dy to the coordinate detection controller 11. The coordinate detection controller 11 detects the peak of the input X coordinate detection signal Dx and determines the X coordinate based on the time when this peak is detected and the scanning timing of the X electrode. Similarly, the Y coordinate is determined based on the peak timing of the input Y coordinate detection signal Dy and the scanning timing of the Y electrode. Then, for example, by transmitting the XY coordinate data to a control unit (not shown) or the like, the control unit performs a required process based on the XY coordinate data.

Various circuit configurations are conceivable for detecting the peak positions of the detected X and Y coordinate detection signals Dx, Dy. For example, the voltage of the distribution curve shown in FIG. 8 is obtained by passing through a simple differentiating circuit. The peak position can be detected by obtaining the signal that inverts at the peak and detecting the zero-cross point.

As described above, in this embodiment, the high-frequency signals of different frequencies are superposed or modulated on the scanning signals of the X and Y electrodes at the time of coordinate detection, and the bandpass filter corresponding to each frequency is detected on the detection side. By outputting to the coordinate detection controller 11 via the X- and Y-coordinates, even if the detection signal on the X electrode side and the detection signal on the Y electrode side are obtained almost simultaneously, The X-coordinate detection signal and the Y-coordinate detection signal can be separately output via this.

Therefore, it is not necessary to temporally divide the scanning period of the X electrode and the scanning period of the Y electrode, and the X electrode and the Y electrode may be simultaneously scanned in the same period. It will be possible. That is, as can be seen by comparing FIG. 2 and FIG. 7 (conventional), the time corresponding to the period for scanning one of the electrodes in the coordinate detection period within one screen display period is shortened. As a result, the actual display period can be lengthened accordingly, and thus the brightness of the display image can be improved. Further, for example, when the brightness obtained during the display period as long as that shown in FIG.
Multiple coordinate detection periods within the screen display period (for example, 2
It is also possible to improve the accuracy of coordinate detection by providing a single screen display period of 1/60 second (about 16.7 ms) to
If the coordinate detection period is set twice for about 1/70 second (about 14.2 ms), the detection speed of 1/120 second is realized, so that character recognition can be supported.

The circuit configuration of the display-integrated tablet shown in this embodiment is an example, and various modifications can be made as long as the tablet has the same effects as the present invention. For example, although the tablet 1 employs the FED in the present embodiment, it is of course possible to apply the present invention to the present invention using a display device having another structure capable of detecting coordinates by capacitive coupling. Even if the ELD described with reference to FIG. 6 is used, the same effect can be obtained. Further, in the present embodiment, as shown in FIG. 2, the coordinate detection period is provided after the display period in the one-screen display period, but it may be provided before the display period. It may be set according to the above. Further, as described above, even when a plurality of coordinate detection periods within one screen display period are provided, the temporal arrangement of the display period and the coordinate detection period is arbitrary.

[0039]

As described above, in the display-integrated tablet of the present invention, high frequency waves having different frequencies are applied as scanning signals to the X and Y electrodes during the coordinate detection period, and at this time, electrostatic coupling is used. Since the detected signals thus obtained can be extracted as the X and Y coordinate detection signals through the band pass filters corresponding to the respective frequencies, the detection scanning of the X electrodes and the Y electrodes can be performed simultaneously. It is possible to shorten the display suspension period in the screen display period. As a result, the actual display period can be taken longer, and the brightness of the display image can be improved.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a display-integrated tablet according to an embodiment of the present invention.

FIG. 2 is a timing chart showing the electrode driving timing within a one-screen display period in the display-integrated tablet of the present embodiment.

FIG. 3 is a timing chart showing an electrode driving timing within a coordinate detection period in the present embodiment.

4A and 4B are a perspective view and a cross-sectional view showing a Spindt-type field emission cathode used in the tablet of the present embodiment.

FIG. 5 is a perspective view showing the structure of the tablet of this embodiment.

FIG. 6 is a block circuit diagram showing a display-integrated tablet in a conventional example.

FIG. 7 is a timing chart showing an electrode scanning timing in a conventional example.

FIG. 8 is an explanatory diagram showing a voltage distribution due to capacitive coupling.

[Explanation of symbols]

1 Tablet 2 Display / Coordinate Detection Signal Controller 3 Y Scan Driver 4 Y Electrode High Frequency Power Supply Section 5 X Scan Driver 6 X Electrode High Frequency Power Supply Section 7 Anode Driver 8 Stylus Pen 9 X Coordinate Bandpass Filter 10 Y Coordinate Bandpass Filter 11 coordinate detection controller 21 first substrate 22 bore 23 and the second substrate 24 anode electrode 25 phosphor y ₁ ~y _n Y electrodes x ₁ ~x _m X electrode C1~Cn cathode terminal G1~Gm gate terminal a anode lead-out electrode

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor So Nagasawa 629 Futaba, Mobara-shi, Chiba Futaba Electronics Co., Ltd.

Claims (1)

[Claims] 1. A tablet having a display surface on which a plurality of X electrodes and Y electrodes for scanning are arranged in a matrix, and X electrode drive means capable of driving each X electrode at a predetermined timing, Y electrode drive means capable of driving each Y electrode at a predetermined timing; a detection conductor to which a coordinate detection signal is input by locating the Y electrode on the tablet on which the X and Y electrodes are driven; X based on the coordinate detection signal supplied from the conductor
In a display-integrated tablet equipped with coordinate detection means capable of detecting coordinates and Y coordinates, first high frequency generation means capable of generating a high frequency signal of a predetermined frequency and outputting the high frequency signal to the X electrode drive means. A second high frequency generating means capable of generating a high frequency signal having a predetermined frequency different from that of the first high frequency generating means and outputting the high frequency signal to the Y electrode drive means; and the second high frequency generating means input from the detection conductor. From the coordinate detection signal,
A first band-pass filter for extracting a frequency corresponding to the first high-frequency generating means and outputting the frequency to the coordinate detecting means; and the coordinate detection signal input from the detecting conductor,
A second band pass filter for extracting the frequency corresponding to the second high frequency generating means and outputting the extracted frequency to the coordinate detecting means is provided, and the X electrode drive means causes the first electrode to operate in the same coordinate detecting period. Scanning is performed while applying the high frequency signal generated by the high frequency generating means to the X electrode, and the Y electrode drive means causes the high frequency signal generated by the second high frequency generating means to the Y electrode. A display-integrated tablet characterized by being configured to scan while being applied.