JPH0766116B2 - Display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention provides an input function in which a function as a coordinate input surface is provided on a flat display panel surface as a means for dialogue between an electronic computer and its operator. The present invention relates to an attached display device.

[Conventional technology]

Conventionally, as a display device with an input function in which a plane display panel surface has a coordinate input function, for example, the following one disclosed in Japanese Patent Laid-Open No. 63-81521 by the present applicant has been proposed.

FIG. 9 is a block diagram of the display device with the input function. In the figure, reference numeral 1 is a liquid crystal cell for TN mode display (a flat panel display panel), and an X transparent electrode 11 and a Y transparent electrode 12 which are orthogonal to each other. And has a structure such that both ends of each transparent electrode can receive a signal from the outside. 21,22 is X
Driver, 31 and 32 are Y drivers, 4 is an input pen,
It is composed of a pickup coil 40 in which a coil is wound around ferrite and a head amplifier 41. Reference numeral 5 is a memory for writing a pattern to be displayed on the liquid crystal cell 1. Reference numeral 6 denotes a liquid crystal display controller, which is a selected Y transparent electrode 12 of the liquid crystal cell 1.
The display control is performed such that the pattern data in the X direction corresponding to is read from the memory 5 and transferred to the X drivers 21 and 22.

A position detection circuit 7 generates a detection signal from the signal from the input pen 4. 8 is a position detection scanning circuit, 9 is an input / output mode controller, and a liquid crystal display controller 6 in the display mode.
Display data and control signals are supplied to the X drivers 21 and 22, and the Y drivers 31 and 32, respectively, and various signals from the position detection scanning circuit 8 are supplied to the X driver in the position detection mode.
21, 22 and Y drivers 31 and 32 play the role of changeover switches to be added respectively. A CPU 10 writes a display pattern in the memory 5 and controls the entire device.

Further, 50 is a display signal applying means, which is the liquid crystal display controller 6, the input / output mode controller 9, the X, Y drivers 21, 31.
It is composed by. 60 is an AC component current applying means,
The input / output mode controller 9, the X, Y drivers 21, 31 are composed of the other position detection scanning circuit 8. Reference numeral 70 denotes a position detection means, which is composed of a position detection circuit 7 and a position detection scanning circuit 8. Reference numeral 80 denotes a mode switching means, which is composed of the CPU 10 and the input / output mode controller 9.

FIG. 10 is a detailed diagram of the configuration relating to the position detection mode in FIG. In the figure, reference numeral 800 denotes a clock generator, the output end of which is through the input / output mode controller 9 the clock input terminal CK of the Y drivers 31 and 32 and the frequency divider 801.
Of the counter 802 and the clock input terminal CK of the counter 802. The output terminal of the frequency divider 801 is connected to the data input terminals D of the Y drivers 31 and 32 and the start terminal S of the counter 802 via the input / output mode controller 9. 803
Is a latch, which latches the output of the counter 802 with a latch pulse (l). 804 is a sine wave generator,
Generates a sine wave with frequency f _o . Reference numeral 805 denotes a grounded-emitter transistor, which generates a sine wave whose phase is 180 ° different from the output sine wave of the sine wave generator 804.

Further, 700 is a bandpass filter whose center frequency is f _o . A phase comparator 701 outputs the phase difference between the sine waves input to the two input terminals P1 and P2 as a voltage level from the output terminal PO. 702 is an operational amplifier. Reference numeral 703 is a comparator, which outputs a coincidence pulse when the output of the phase comparator reaches a constant level.

31 and 32 are the same drivers for Y as those shown in FIG. 9, but actually have a shift register of n stages inside, and the data input terminal D by the clock pulse of the clock input terminal CK.
The data of is sequentially shifted. The output terminal (Oi) (i = 1 to n) of the driver is connected to the data (D
i) (i = 1 to n) and one of the voltages applied to the voltage application terminals V1, V2, V3, and V4 depending on the value of the alternating current terminal (DF). The truth table of the output voltage is shown in FIG. In addition, the constant voltage E1, E2, E3 is applied to the voltage application terminals V1, V2, V3.
The DC voltage E4 is applied to the terminal V4 via the input / output mode controller 9 in the display mode, and two sine wave voltages different in phase by 180 ° are applied in the position detection mode.

The internal switch group of the input / output mode controller 9 is
As shown by the broken line in the display mode as shown in Fig. 10,
In the position detection mode, the connection is made as shown by the solid line.

Further, in FIG. 10, Y drivers 31, 32 and Y transparent electrodes 121 to 12 are shown.
Although only n is shown, the X driver and the X transparent electrode are actually provided at positions orthogonal to these, and in the position detection mode, they operate similarly to the Y driver and the Y transparent electrode.

Further, FIG. 11 is a configuration diagram of a liquid crystal cell of a conventional display device with an input function. In the figure, 111, 112, ..., 11k are X transparent electrodes, 12
1,122, ..., 12n is Y transparent electrode, 1000 is X side glass plate, 1001
Is a Y-side glass plate, 1002 is a spacer, and 1003 is a liquid crystal.

FIG. 12 is a view showing a cross section of FIG. 11.

Next, the operation will be described.

A conventional display device with an input function repeats a display mode and a position detection mode in a fixed cycle in a time-division manner. That is, as shown in FIG. 14, one frame period is divided into (n + 2) periods, the display mode is operated from the periods T ₁ to T _n, and the position detection mode is operated from the periods T _{n + 1} and T _{n + 2} .

First, in the display mode, the internal switch group of the input / output mode controller 9 is connected as shown by the broken line in FIG. 10, and the liquid crystal display controller 6 sequentially reads out the data of the pattern to be displayed from the memory 5, which is conventionally known. Display is performed by the voltage averaging drive method. That is, DC voltage (E1, E
2, E3, E4) is set to a bias voltage suitable for the voltage averaging driving method, the period _{T 1, T 2, ...,} Y transparent electrodes 121 and 122 for each T _n,
, 12n are sequentially applied with the selection voltage, and the display signal corresponding to the selected Y transparent electrode 12 is applied to the X transparent electrode 11 every period.
Applied to. At this time, each X transparent electrode 11 and Y transparent electrode
The driver outputs across 12 output the same voltage.

Next, the position detection mode will be described with reference to FIG.
In the period T _{n + 1} , the internal switch group of the input / output mode controller 9 is connected as shown by the solid line in FIG. 10, and the Y coordinate of the position of the input pen 4 is detected.

In the position detection mode, the V4 terminal of 31 of the Y driver 31 and the V4 terminal of the Y driver 32 have a sine wave voltage V _n sin (2πf _o t) generated by the sine wave generator 804 and the sine wave voltage V _n sin (2πf _o t)
In 805, a sine wave voltage of −V _m sin (2πf _o t) whose phase is shifted by 180 ° is applied. Furthermore, since the DF terminals of the Y drivers 31 and 32 are grounded, the output Oi of the Y drivers 31 and 32 is Oi.
In (i = 1 to n), the DC voltage E2 is when the data of the internal shift register is "L", and the sine wave voltage V _m sin when it is "H".
(2πf _o t) or −V _m sin (2πf _o t) is output.

Basic clock C generated by clock generator 800
The start pulse SP (FIG. 15SP) output by dividing the frequency (FIG. 15C) by (n + d) by the frequency divider 801 resets the counter 802 to start counting, and the Y drivers 31, 32.
Is supplied to the data input terminal D of the shift register. After that, each time one basic clock pulse C is generated, the output value of the counter 802 is incremented by "1", and in synchronization with this, the data in the internal shift registers of the Y drivers 31 and 32 are shifted by one. , The Y transparent electrodes 12 to which a voltage of ± V _m sin (2πf _o t) is applied to both ends are shifted one by one. That is, assuming that the resistance value of the Y transparent electrode 12 is R _o , the Y transparent electrodes 121, 122, ..., 12 m are sequentially (2 V _m / R _o ) · sin (2πf
_o t) sine wave current flows.

At this time, the pickup coil 40 of the input pen 4 placed at the X position on the Y transparent electrode 12m is caused by the component of the AC magnetic flux generated by the sinusoidal current flowing through each transparent electrode 12 perpendicular to the liquid crystal cell 1 surface. Electricity is generated. This electromotive force has the same frequency as the sine wave current flowing through the Y transparent electrode 12 and a phase difference of 90 °, and the magnitude of the level is inversely proportional to the distance between the point X and the Y transparent electrode 12 through which the sine wave current flows. It becomes a sine wave.
However, when the current is flowing through the Y transparent electrode 12m at the point X, the distance becomes the shortest, but the magnetic flux of the component perpendicular to the surface of the liquid crystal cell 1 becomes almost zero, so that the output of the pickup coil 40 becomes almost zero. The output signal of the pickup coil 40 is amplified by a head amplifier 41, passes through the bandpass filter 700 having a center frequency f _o in order to increase the S / N ratio. FIG. 15B shows an output waveform of the handle pass filter 700 when a current is sequentially passed through the Y transparent electrode 12 one by one as described above.

In addition, the Y driver 3 is connected to the two input terminals of the differential amplifier 702.
Each sine wave voltage applied to 1,32 V4 terminals ± V _m si
Since n (2πf _o t) is applied, Y transparent electrode 12
A sine wave proportional to the current flowing through is output (see FIG. 15 (r)).

As can be seen from FIG. 15, the phase of the output signal b of the bandpass filter 700 is the period during which a current is passed from the Y transparent electrodes 121 to 12m and the period during which a current is passed from the Y transparent electrodes 12 (m + 1) to 12n. Then it differs by 180 degrees. Therefore the differential amplifier 702
When the output signal r of the output signal p of the bandpass filter 700 and the output signal b of the bandpass filter 700 are input to the phase comparator 701, the waveform of the output signal p is 15th.
It looks like Figure p. When the reference potential terminal B of the comparator 703 is set to the potential of VR, the comparator 703 outputs the coincidence pulse 1 when the level of the output p of the phase comparator 701 becomes VR, and the latch 803 latches the output of the counter 802 at that time. To do.

That is, an alternating current is sequentially applied to the Y transparent electrode 12 for scanning,
When the m-th transparent electrode 12m where the input pen 4 is located scans, the comparator 703 generates a coincidence pulse, and the counter 8
Latch the output value m of 02. The output value of this latch 803 is C
When the PU 10 reads, the Y coordinate of the position of the input pen 4 is detected.

The operation described above is performed during the period T _{n + 1} in FIG.
Same operation for T _{n + 2} X drivers 21, 22, X transparent electrode 11
The position X coordinate of the input pen 4 is detected.

[Problems to be solved by the invention]

Since the conventional display device with an input function is configured as described above, the drive scan of the display electrodes for display must be performed over all the electrodes in order, and a certain display electrode is selected. After that, the scanning time of the entire one screen is kept waiting until the next selection, and there is a problem that the display contrast is lowered.

The present invention has been made to solve the above problems, and an object thereof is to obtain a display device with an input function having a high display contrast.

[Means for solving problems]

In the display device according to the present invention, the display electrode of the flat panel display panel is divided into at least two or more parts, and a dielectric member is formed in each of the divided parts so as to be in contact with each divided end of the display electrode. .

[Action]

In the display device according to the present invention, the display electrodes are divided and capacitively coupled, so that the electric characteristics between the divided display electrodes are opened in terms of direct current, and the drive scanning of the display electrodes is divided. Since it can be performed in the same time for each electrode group, the time during which each display electrode is selected increases and the display contrast increases.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
Figure shows a display device according to an embodiment of the present invention, in _{FIG., 11a 1, 11a 2, ...} , 11a k is a side X transparent electrode, 11b _1, 11b _2,
, 11b _k are b-side transparent electrodes, 11c ₁ , 11c ₂ , ..., 11c _k are the a-side X transparent electrodes 11a ₁ , 11a ₂ , ..., 11a _k and b-side transparent electrodes 11b ₁ , 11
b _2, ..., arranged in contact with and 11b _k, for example踏電member consisting of barium titanate, 1000 X-side glass plate,
1001 is a Y side glass plate, 1002 is a spacer, 1003 is a liquid crystal, and the X side glass plate 1000 and the Y side glass plate 1001 are spacers.
They are bonded together via 1002, and a liquid crystal 1003 is enclosed between them.

Although not shown, polarizing plates are installed on the X-side glass plate 1000 and the Y-side glass plate 1001.

FIG. 2 is a view showing a cross section of FIG.

The operation will be described below. A driving device for operating the liquid crystal cell configured as the present invention as a display device with an input function is the same as that shown in the conventional example of FIG. . However, as will be described later, only the drive timing is different.

In the liquid crystal cell shown in FIG. 1, a-side X transparent electrodes 11a ₁ , 11a ₂ , ..., 11a _k and b-side X transparent electrodes 11b ₁ , 11b ₂ ,.
Since b _{k is in} contact with the conductive members 11c ₁ , 11c ₂ , ..., 11c _k , both electrode groups are galvanically insulated, and the a-side X transparent electrode 11a ₁ , 11a _2, ..., 11a _k and b-side X transparent electrode 11b _1, 11b _2, ..., independently of each other and 11b _k, it is possible to apply the display voltage from the X driver 21. Therefore, when the liquid crystal cell of FIG. 1 is used, the a-side X transparent electrode 11
_{a 1, 11a 2, ...,} 11a k and b-side X transparent electrode 11b _1, 11b _2, ..., and 11b _k can be performed separately displayed at the same time. Next, the state of displaying in time division will be described.

The dielectric member 11c _1, 11c _2, as FIG. 3, ..., installation location is Y transparent electrodes 121 and 122 of 11c _k, ..., When it is at half the number of 12n, shown in Figure 4 Of display mode
At the time of T ₁ cycle, scanning for sequentially applying a selection voltage as shown in the conventional example is performed with the Y transparent electrode 121. Try to do both at the same time. That side, a side X transparent electrode
_{11a 1, 11a 2, ...,} 11a k and b-side X transparent electrode _{11b 1, 11b 2, ...,} 11b k
121 of Y transparent electrode and The display data of and are output separately at the same time. In the next T ₂ cycle, the Y transparent electrodes 121, 122, ... : It is selected, similarly a side X transparent electrode 11a ₁ in the case of the X transparent electrode _{T 1, 11a 2, ...,} 11a k and b-side X transparent electrode 11b _1, 11b _2, ...,
11b _k and 122 of Y transparent electrode respectively The display data of is output separately at the same time. Similarly T
_{When n / 2} cycles are reached, all the Y transparent electrodes 121, 122, ..., 12n are selected, and one frame in the display mode is completed.

As described above, in the conventional example, the Y transparent electrodes 121 and 12 are provided in one frame.
It requires the same number of n cycles as 2, ..., 12n,
When the liquid crystal shown in FIG. 1 is used, display can be performed in half the cycle of n / 2 that of the conventional example. If the cycle of one frame is the same, the cycle of selecting one Y transparent cell 121, 122, ..., 12n is doubled. That is, the time selected for display increases and the display contrast increases.

Next, the operation in the position detection mode in the liquid crystal cell configured as in the present invention will be described.

a side X transparent electrodes 11a ₁ , 11a ₂ , ..., 11a _k and b side X transparent electrodes 11b
_When a pair of electrodes 11 ₁ , 11 b ₂ , ..., 11 b _k face each other, the a-side X transparent electrode and the b-side X transparent electrode as shown in FIG. It is expressed as being connected in series with a space between them. As shown in FIG. 6, the impedance of this capacitor has a sufficiently low value at the frequency of the alternating current that generates the alternating magnetic flux for position detection. Therefore, in the position detection mode, the liquid crystal cell of FIG. 1 is considered to have the same characteristics as the liquid crystal cell of the conventional example of FIG. 11, and position detection can be realized by the same operation as the conventional example.

In the above example, the dielectric substance is arranged to form the capacitance component at the division points of the transparent electrode of the liquid crystal cell,
A method of forming a capacitance component by utilizing the dielectric constant of liquid crystal is also conceivable, and a method of shortening the length t of the gap between the division points of the transparent electrode as shown in FIG. 7 or shown in FIG. Such a method is to increase the surface area of the surface of the transparent electrode facing the dividing points, and any of them can obtain the same effect as that of the above embodiment.

Further, in the above-described embodiment, the flat-panel display panel using liquid crystal has been described, but a display device having a similar XY Marix electrode configuration may be provided, and the same effect as that in the above-described embodiment is obtained.

〔The invention's effect〕

As described above, according to the display device of the present invention, the divided transparent electrodes are AC-coupled at the dividing points, and the DC current is maintained while maintaining the property that an AC current for generating the detection magnetic flux can be applied. Insulation is applied to the display, and the DC voltage for display can be applied to the divided transparent electrode groups independently of each other. Therefore, two or more transparent electrode groups can be independently displayed at the same time, and selection per transparent electrode is possible. The time becomes longer and the display contrast is improved.

[Brief description of drawings]

1, 2 and 3 are views showing the structure of a liquid crystal cell of a display device according to an embodiment of the present invention, and FIG. 4 is a display device using the liquid crystal cell according to the embodiment of the present invention. FIG. 5 is a diagram showing an electrical equivalent circuit between transparent electrodes constructed according to the present invention. FIG. 6 is a diagram showing electrical characteristics between transparent electrodes constructed according to the present invention. Figure, 8th
FIG. 9 is a diagram showing a capacitance forming method showing another embodiment of the present invention, FIGS. 9 and 10 are configuration diagrams of a conventional display device, and FIG.
Fig. 12 and Fig. 12 are views showing the structure of a conventional liquid crystal cell, Fig. 13 is a view showing a truth table for explaining output values of a driver, and Fig. 14 is a view showing a display mode and a position detection mode of a conventional display device. FIG. 15 is a diagram for explaining the time-sharing operation, and FIG. 15 is an output waveform diagram of main signals in FIG. In the figure, 1 is a liquid crystal cell (flat display panel), 11
_{a 1, 11a 2, ...,} 11a k is a side X transparent _{electrode, 11b 1, 11b 2, ...} , 11b k
Is a b-side X transparent electrode, 11c ₁ , 11c ₂ , ..., 11c _k is a dielectric member, 1
21,122, ..., 12n is Y transparent electrode, 1000 is X side glass plate, 100
1 is a Y-side glass plate, 1002 is a spacer, 1003 is a liquid crystal, 5 is a memory, 6 is a liquid crystal display controller, 7 is a position detection circuit, 8 is a position detection scanning circuit, 9 is an input / output mode controller, and 21 and 31 are X. , Y driver, 4 input pen, 40 pickup coil (magnetic flux detection means), 41 head amplifier,
50 is a display signal applying means, 60 is an AC component current applying means,
70 is a position detecting means, and 80 is a mode switching means. The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Iwata 8-1-1 Tsukaguchihonmachi, Amagasaki-shi, Hyogo Sanryo Electric Co., Ltd. Applied Equipment Research Laboratory (56) Reference JP-A-61-210397 (JP, A) ) JP-A-61-294413 (JP, A) JP-A-57-157339 (JP, A)

Claims (5)

[Claims] 1. A flat display panel having an XY matrix electrode structure, display signal applying means for applying a display signal to the XY matrix electrodes in a display mode, and XY in an input position detection mode. An alternating current component current applying means for flowing a current having an alternating current component whose voltage changes in a constant cycle to at least one of the matrix electrodes, an input pen having a magnetic flux detecting means, and a signal generated by the magnetic flux detecting means. A display device comprising position detection means for detecting the position of the input pen on the display panel, and mode switching means for switching the operation mode of the display device so as to alternately repeat the display mode and the input position detection mode. , Each electrode of at least one of the XY matrix electrodes of the flat display panel is divided into at least two systems A display device impedance in the divided portion of the divided electrodes, who during the alternating component current applied is characterized in that set to be sufficiently smaller than the time the display signal is applied. 2. A display device according to claim 1, wherein an electrostatic capacitance member is arranged in a gap between the divided electrodes. 3. The gap between the divided electrodes is formed such that the gap width is sufficiently smaller than the long side gap width of the adjacent electrodes in the electrode group. Display device according to item. 4. The display device according to claim 1, wherein the end portions of the divided electrodes are shaped such that the surface area of the gap portion is larger than the surface area of the simple rectangular end portions facing each other. . 5. The display device according to claim 1, wherein said display signal applying means simultaneously performs drive scanning of each divided electrode group within a display mode of the same cycle.