Touch-controlled liquid crystal display and touch panel thereof

A touch-controlled LCD includes a liquid crystal display panel and a touch panel. The liquid crystal display panel includes a first substrate, a second substrate and a liquid crystal layer disposed between the first substrate and the second substrate. The touch panel is disposed on a side of the second substrate facing away from the liquid crystal layer. The touch panel includes a plurality of first electrodes being parallel to each other, a plate shaped second electrodes facing the first electrodes, and a plurality of spacers disposed between the first electrodes and the second electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 97130352, filed Aug. 8, 2008, the full disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to a touch-controlled liquid crystal display and a touch panel thereof, and more specifically, to a multi-touch liquid crystal display and a touch panel thereof.

2. Description of Related Art

With the development of electronic technology, touch panel as an input apparatus has been widely used in various kinds of flat panel display devices such as liquid crystal displays (LCDs). Currently, touch panels can be divided into three categories: resistive panels, capacitive panels and inductive panels, among which resistive panels are especially popular because of their simple manufacturing process and the low manufacturing cost.

A touch panel of a typical LCD normally includes an upper conductive substrate, a lower conductive substrate, and a spacer disposed therebetween. The upper and lower conductive substrates respectively include a substrate and a conductive film covered thereon. The conductive film can be an ITO (Indium Tin Oxide) film. A resistive touch panel usually detects the touching position by sensing a distributed voltage and only one touching position can be detected at a time. If a user touches and presses more than one place on the touch panel, the touch panel is incapable of detecting the multiple touched positions. In other words, the conventional resistive touch panels cannot be controlled in a multi-touch fashion, which greatly limits the application of touch-controlled displays.

BRIEF SUMMARY

An object of the present invention is to provide a touch-controlled LCD that can be controlled in a multi-touch fashion.

Another object of the present invention is to provide a multi-touch touch panel.

A touch-controlled LCD according to a preferred embodiment of the present invention is provided. The touch-controlled LCD includes a liquid crystal display panel and a touch panel. The liquid crystal display panel includes a first substrate, a second substrate and a liquid crystal layer disposed between the first substrate and the second substrate. The touch panel is disposed on a side of the second substrate facing away from the liquid crystal layer. The touch panel includes a plurality of first electrodes being parallel to each other, a plate shaped second electrodes facing the first electrodes, and a plurality of spacers disposed between the first electrodes and the second electrode so as to separate the first electrodes and the second electrode.

A touch panel for realizing multi-touch control of a flat panel according to a preferred embodiment of the present invention is provided. The touch panel includes a plurality of first electrodes parallel with each other; a plate shaped second electrode facing the first electrodes; and a plurality of spacers disposed between the first electrodes and the second electrode for separating the first electrodes and the second electrode.

DETAILED DESCRIPTION

Referring toFIG. 1, a touch-controlled LCD10according to a preferred embodiment of the present invention is provided. The touch-controlled LCD10includes a LCD panel20and a touch panel30.

The LCD panel20includes a first substrate21, a second substrate22and a liquid crystal layer23disposed between the first substrate21and the second substrate22. In this embodiment, the first substrate21can be a thin film transistor (TFT) substrate, on which a plurality of thin film transistors are disposed. The second substrate22can be a color filter (CF) substrate, on which a plurality of color filters are disposed.

The touch panel30is disposed on the LCD panel20. More specifically, the touch panel30is disposed on a side of the second substrate22that is facing away from the liquid crystal layer23. The touch panel30includes multiple first electrodes21, which are parallel with each other, a plate shaped second electrode32, and multiple spacers33. The plate shaped second electrode32is disposed facing the first electrodes31. The spacers33are disposed between the first electrodes31and the second substrate32so as to separate the first electrodes31and the second substrate32.

In this embodiment, the touch-controlled LCD10further includes a polarizer41and a polarizer42. The polarizer41is disposed on the first substrate21of the LCD panel20. The second polarizer42is disposed on the touch panel30.

In addition, in this embodiment, the first electrodes31are disposed on a side of the second substrate22that is facing away from the liquid crystal layer23. The first electrodes31can be formed by applying transparent conductive layers that are parallel with each other and made from ITO onto the second substrate22. The plate shaped second electrode32and the first electrodes31are respectively disposed on the two sides of the spacers33. The second electrode32can be in contact with the polarizer42.

It is to be understood that, in practice, the first electrodes31and the plate shaped electrode32can be exchanged in position. In other words, the second electrode32can be disposed on a side of the second substrate22that is facing away from the liquid crystal layer23. In addition, the first electrodes31are parallel with and spaced from each other so that they are insulated from one another. The spacers33can be made from transparent and elastic materials.

Referring to2A-2B, a schematic diagram of a detecting circuit of the touch panel30, the touch panel30further includes multiple control switch pairs [Y1a, Y2a], . . . , [Y1h, Y2h], a demultiplexer35and a power supply36. The control switch pairs [Y1a, Y2a], . . . , [Y1h, Y2h] are respectively electrically coupled to the first electrodes31. The number of the control switch pairs [Y1a, Y2a], . . . , [Y1h, Y2h] corresponds to the number of the first electrodes31. In this embodiment, the first electrodes31include eight electrodes A1, A2, . . . A8, and the corresponding eight control switch pairs [Y1a, Y2a], . . . , [Y1h, Y2h].

The outputs of the demultiplexer35are respectively electrically coupled to the control switch pairs [Y1a, Y2a], . . . , [Y1h, Y2h] so as to control the open/closed status thereof. The demultiplexer35is an m to n demultiplexer, wherein 2m≧n. In this embodiment, the demultiplexer35is a 3 to 8 demultiplexer. A scanning signal is input to the inputs of the demultiplexer35so that the outputs of the demultiplexer35output corresponding control signals that sequentially close the control switch pairs [Y1a, Y2a], . . . , [Y1h, Y2h]. Thus, the electrodes A1, . . . , A8can be sequentially electrically coupled to the power supply36through the control switch pairs [Y1a, Y2a], . . . , [Y1h, Y2h]. The scanning signal can be a digital signal.

In this embodiment, a coordinate is constructed wherein the direction parallel with the extending direction of A1, . . . , A8is taken as the Y axis. By sequentially scanning A1through A8, the Y coordinate of the touched point is detected as follows.

When t=t1, the scanning signal that is input into the inputs of the demultiplexer35is 000, the control signal output from the demultiplexer35is 00000001. Now the first control switch pair [Y1a, Y2a] is closed to connect the two sides of the electrode A1so that the electric potential on the electrode A1VSS=VCC, as shown inFIG. 2A. At this moment, all other control switch pairs [Y1b, Y2b], . . . , [Y1h, Y2h] are open so that the two sides of the other electrodes A2, . . . , A8are not connected. This is the time when the electrode A1is scanned to detect whether the touched point is located on the electrode A1.

After a time period of Δt, that is, when t=t1+Δt, the input scanning signal at the inputs of the demultiplexer35changes to 001, and the corresponding outputs of the demultiplexer35changes to 00000010. Now, the first control switch pair [Y1a, Y2a] is open so as to disconnect the two sides of the electrode A1, and the second control switch pair [Y1b, Y2b] is closed so as to connect the two sides of the second electrode A2. Thus, the electric potential on the electrode A2VSS=VCC, and all electrodes A1, . . . , A8except A2are floating. This is the time when the electrode A2is scanned to detect whether the touched point is located on the electrode A2.

By the above rules, when t=t1+(n−1)Δt, the input scanning signal at the inputs of the demultiplexer35changes to 111, and the corresponding outputs of the demultiplexer35changes to 10000000. Now, the eighth control switch pair [Y1b, Y2b] is closed so as to connect the two sides of the eighth electrode A8. This is the time when the electrode A8is scanned to detect whether the touched point is located on the electrode A8. This way, the system has conducted a complete scan to the touch panel.

By sequentially scanning the multiple electrodes A1, . . . , A8, the electrode where the touched point is located can be accurately detected and the Y coordinate of the touched point can be further determined. In addition, by measuring the voltage distributed on that electrode, the X coordinate of the touched point can be calculated.

It is to be understood that the detecting circuit provided by this embodiment scans the electrodes in a time sequence. As a result, even when there are multiple touched points, the Y coordinates of these touched points can still be accurately detected, and the X coordinates thereof can be calculated from the distributed voltages. Hence, multi-touch control is realized by the touch panel30provided by this embodiment and LCD displays having the touch panel30.

Referring toFIG. 3A-3B, a touch panel according to another embodiment of the present invention is provided. The resistive touch panel includes multiple first control switch pairs [Y1a, Y2a], . . . , [Y1h, Y2h], two second control switch pairs [W0, G1] and [W1, G0], a first demultiplexer351, a second demultiplexer352, a first power supply361and a second power supply362. The output voltage of the first power supply361is the same as the second power supply362. The first control switch pairs [Y1a, Y2a], . . . , [Y1h, Y2h] are respectively electrically coupled to the electrodes A1, . . . , A8. The number of the first control switch pairs [Y1a, Y2a], . . . , [Y1h, Y2h] corresponds to the number of the electrodes. In this embodiment, there are eight electrodes A1, . . . , A8and eight first control switch pairs one-by-one corresponding to the eight electrodes.

In this embodiment, referring toFIG. 3Athe second control switch pairs [W0, G1] and [W1, G0] are used to control an electrode, for example, the electrode A1, so that the voltage of the right side of the electrode is higher than the voltage of the left side of the electrode, after which the configuration of the second control switch pairs [W0, G1] and [W1, G0] is changed so that at a different time the voltage of the left side of the electrode is higher than the voltage of the right side of the electrode. This method can be called crossover scanning, by which the possibility of the system making an error judgment can be decreased.

Referring toFIG. 4, a touch-controlled LCD100according to still another embodiment of the present invention is provided. The LCD100is similar to the LCD10provided by the embodiment inFIG. 1except that the LCD100further includes a polyester film500disposed between the polarizer420and the touch panel300. The polyester film500can be a Polyethylene Terephthalate (PET) film. The plate shaped second electrodes of the touch panel300can be formed by applying a transparent conductive layer, such as an ITO (Indium Tin Oxide) layer, onto the PET film500.

Referring toFIG. 5, a touch-controlled LCD1000according to yet another embodiment of the present invention is provided. The LCD1000is similar to the LCD10provided by the embodiment inFIG. 1except that the LCD1000further includes a polyester film5000disposed between the second substrate of the LCD panel2000(the CF substrate) and the touch panel3000. The polyester film500can be a Polyethylene Terephthalate (PET) film. The first electrodes of the touch panel3000can be formed by applying multiple transparent conductive layers, such as ITO (Indium Tin Oxide) layers, that is parallel to each other onto the PET film5000.

In the above embodiments, the touch panel and the LCD having the touch panel includes multiple first electrodes. By sequentially scanning these electrodes, first coordinates of touched points can be determined; by further measuring the distributed voltages on the electrodes, second coordinates of the touched points can be determined. Thus multi-touch control on a LCD is achieved.