JPH0261758B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display in which a plurality of display parts in a liquid crystal display panel are selectively displayed by touching touch electrodes corresponding to the display parts.

As shown in FIG. 1, a conventional liquid crystal display of this type has a plurality of display sections ₁₁ to 1o on a liquid crystal display panel 11 _.
are provided, and touch electrodes 2 ₁ to 2 _o are provided corresponding to these display sections 1 ₁ to 1 _o . These touch electrodes 2 ₁ to 2 _o are connected to the power supply terminal 12 through resistors 3 ₁ to 3 _o , respectively, and the touch electrodes 2 ₁ to 2 _o are connected to waveform shaping amplifiers 4 ₁ to 4 _o , respectively. These amplifiers 4 ₁ to 4
The outputs of _o are passed through smoothing circuits 5 ₁ to 5 _o , respectively.
For example, a control unit 13 consisting of a microcomputer
supplied to

When a person is not touching the touch electrodes 2 ₁ to 2 _o , a constant voltage is applied from the power supply terminal 12 to the input side of each amplifier 4 ₁ to 4 _o , and this voltage is inverted. For example, negative voltages are output, and these outputs are applied to the control unit 13 through smoothing circuits 5 ₁ to 5 _o . The control unit 13 detects negative voltage input from the smoothing circuits 5 ₁ to 5 _o and determines that the touch electrodes 2 ₁ to 2 _o are not touched.

On the other hand, phase switching circuits 6 ₁ to 6 _o consisting of exclusive OR circuits are provided corresponding to each of the display sections 1 ₁ to 1 _o of the liquid crystal panel 11. This phase switching circuit 6 ₁
A rectangular wave oscillation circuit 14 is connected to _one input side of the
A rectangular wave voltage is also applied to the common electrode terminal 15 of the liquid crystal panel 11. Control signals are input from the control section 13 to the other input sides of the phase switching circuits 6 ₁ to 6 _o , respectively. The output sides of the phase switching circuits 6 ₁ to 6 _o are connected to individual electrodes of the display sections 1 ₁ to 1 _o , respectively.

Therefore, as mentioned above, the touch electrodes 2 ₁ to 2 _o
When none of the buttons are touched, the control unit 13 gives a logic “0” control signal to the phase switching circuits 6 ₁ to 6 _o , and therefore the common electrode of the liquid crystal panel 11 and each display unit are connected to each other. A rectangular wave voltage from an oscillation circuit 14 is applied between the individual electrodes in the same phase. Therefore, no voltage is applied between the common electrode and the individual electrodes of the liquid crystal panel 11, and the display portions 1 ₁ to 1 _o
is not displayed.

However, when a person touches the touch electrode, for example ₂₁ , with a fingertip, the nearby 50Hz or 60Hz commercial power supply voltage is induced in the person, and that induced voltage is amplified by the amplifier ₄₁ .
This is smoothed by the smoothing circuit ₅₁ , and the control unit 13
A high level is given to The control unit 13 determines from this high-level input that the touch electrode 2 ₁ has been touched, and correspondingly applies logic "1" to the phase switching circuit 6 ₁ . Therefore, the output of the phase switching circuit 6 ₁ becomes a rectangular wave voltage having an opposite phase to the output of the oscillation circuit ₁₄ , and the rectangular wave voltage is applied between the individual electrodes and the common electrode for the display section 1 ₁ . A display appears. In this way, by touching the touch electrodes 2 ₁ to 2 _o corresponding to what is desired to be displayed in the display sections 1 ₁ to 1 _o of the liquid crystal display panel 11, only the corresponding display section can be selectively displayed. can.

In this way, in conventional liquid crystal displays, AC drive is generally performed in consideration of the lifespan of the liquid crystal display panel 11, and therefore, the phase switching circuits ₆₁ to _6o depend on whether or not the touch electrode is touched.
is used to switch the phase of the rectangular wave voltage of the rectangular wave oscillation circuit 14, thereby selectively displaying a desired portion of the display panel by AC drive. In other words, in the conventional liquid crystal display, the amplifier circuits 4 ₁ to 4 _o amplify the induced voltage from the touch electrode.
and a resistor 3 ₁ to which a fixed voltage is applied.
3o to _3o , smoothing circuits ₅₁ to _5o that smooth the output of the amplifier circuit, a control section 13 that determines the output of the smoothing circuit and outputs a control signal, and phase switching circuits ₆₁ to _6o are required. The structure was relatively complex.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device with a simple configuration that allows selective display of a display portion of a liquid crystal display panel by touching a touch electrode.

According to this invention, the induced voltage obtained when a touch electrode is touched is amplified to a predetermined voltage, and the amplified output voltage is used as a drive signal to the individual electrode of the display section corresponding to the touch electrode of the liquid crystal display panel. A voltage approximately half of the amplified output voltage is fixedly applied to the common electrode of the liquid crystal display panel. In this way, the structure of the driving section for the liquid crystal display panel can be made extremely simple.

FIG. 2 shows an example of a liquid crystal display according to the present invention, and parts corresponding to those in FIG. 1 are given the same reference numerals. The touch electrodes 2 ₁ to 2 _o are connected to amplifier circuits 7 ₁ to 7 _o , respectively, so that the induced voltage generated when the touch electrodes are touched is amplified to a predetermined voltage. These amplifier circuits 7 ₁ to 7 _o are
For example, a linear amplification circuit consisting of so-called CMOS amplification circuits 4 ₁ to 4 _o and negative feedback resistors 8 ₁ to 8 _o connected between their input and output sides can be used.

The output sides of the amplifier circuits 7 ₁ to 7 _o are connected to the individual electrodes of each display section 1 ₁ to 1 _o of the liquid crystal display panel 11, respectively. From the fixed voltage circuit 16,
A voltage that is half the output voltage of the amplifier circuits 7 ₁ to 7 _o is generated, and this fixed voltage is applied from the terminal 15 to the common electrode of the liquid crystal display panel 11 . For example, the fixed voltage circuit 16 connects the power supply terminal 12 to resistors 17 and 18.
The connection point of these resistors 17 and 18 is connected to the terminal 15. Resistor 1
By setting 7 and 18 to have the same resistance value, 1/2 the voltage of the power supply terminal 12 is applied to the terminal 15. As mentioned above, by configuring the amplifier circuits ₇₁ to _7o with CMOS and negative feedback resistors, the voltage of the power supply terminal 12 for operation of these amplifier circuits is applied to the output side when the input is zero. It is possible to obtain an output voltage with 1/2.

In this configuration, when none of the touch electrodes 2 ₁ to 2 _o is touched, a voltage V _cc /2, which is 1/2 of the voltage at the power supply terminal 12, is applied to the output side of the amplifier circuits 7 ₁ to 7 _o . Therefore, this signal is applied to each individual electrode of each display section ₁ to 1 _o of the liquid crystal display panel.
V _cc /2 is applied and the common electrode is connected to terminal 15.
_Vcc /2 is applied from the fixed power supply circuit 16 through the terminal. Therefore, each display section ₁ of the liquid crystal display panel
No voltage is applied between the ~1 _o individual electrodes and the common electrode, and no display appears.

However, when a touch electrode, for example ₂₁ , is touched, the induced voltage is amplified by the amplifier circuit ₇₁ ,
On the output side, the amplitude is 0 to 0 as shown in Figure 3.
An alternating voltage that varies between V _cc is obtained. This AC voltage is applied to the individual electrodes of the display section ₁₁ , and _Vcc /2 is applied to the common electrode of the liquid crystal display panel 11, so that only the display section ₁₁ is AC driven and its display appears. In this way, only the display section corresponding to the touched touch electrode can be driven with alternating current to display a display.

Compared to the conventional configuration shown in FIG. 1, the configuration shown in FIG. 2 does not require a smoothing circuit, a phase switching circuit, a control unit, or a rectangular wave oscillation circuit, and is extremely simple and inexpensive to configure. Can be done. Note that when the touch electrode is used to perform not only selective display of the display section of the liquid crystal display panel but also other controls, the outputs of the amplifier circuits ₇₁ to _7o are transferred to the smoothing circuits 51 _{to 7o} , respectively. The output may be smoothed by 5 _° and applied to the control unit 13, and the control unit 13 may detect the touch state of the touch electrode and perform necessary control. The touch electrodes 2 ₁ to 2 _o may be provided at locations corresponding to the respective display sections 1 ₁ to 1 _o or on the display sections themselves. When provided on the display section, use a transparent electrode. In this liquid crystal display, a corresponding display section is displayed as the touch electrode is touched, and such a display is effective in, for example, a game machine.

[Brief explanation of the drawing]

Figure 1 is a connection diagram showing a conventional liquid crystal display;
The figure is a connection diagram showing an example of a liquid crystal display according to the present invention, and FIG. 3 is a diagram showing an example of an output waveform of an amplifier circuit when a touch electrode is touched. 1 ₁ to 1 _o : display section, 2 ₁ to 2 _o : touch electrode, 7 ₁ to 7 _o : amplifier circuit, 11: liquid crystal display panel, 12: power supply terminal, 16: fixed voltage circuit.

Claims (1)

[Claims] 1. A liquid crystal display panel having a plurality of display parts, a plurality of touch electrodes provided corresponding to each of the plurality of display parts in the liquid crystal display panel, and a touch electrode connected to each of the touch electrodes. a plurality of amplifying circuits that amplify the induced voltage obtained when the liquid crystal panel is turned on to a predetermined voltage and apply the amplified voltage to the electrodes of corresponding display parts in the display panel; A liquid crystal display equipped with a fixed voltage circuit that applies a fixed voltage of /2.