Patent ID: 12189251

DETAILED DESCRIPTION

The term “coupled” or “connected” used throughout the present disclosure may refer to two or more elements physically or electrically contact with each other in direct, or physically or electrically contact with each other in indirect, or two or more elements interact or act on each other. In addition, although terms such as “first”, “second”, etc. are used in the present disclosure to describe different elements, these terms are only used to distinguish elements or operations described by the same technical terms. Unless clearly indicated, the terms do not specifically refer to or imply a sequence or an order, nor are they intended to limit the present disclosure.

Reference will now be made in detail to the present embodiments of the disclosure, examples of which are illustrated in the accompanying drawings.

Since some components of the touch screen100of the present disclosure overlap each other in a vertical direction, in order to clearly describe the structure of the touch screen100, please refer toFIG.1andFIG.2together.FIG.1is a simplified block diagram of a pixel circuit matrix and related control circuits of the touch screen100in accordance with some embodiments of the present disclosure.FIG.2is a simplified block diagram of a touch electrode matrix and related control circuits of the touch screen100in accordance with some embodiments of the present disclosure. In some embodiments, the touch screen100comprises a plurality of scan lines SL[1]-SL[M], a controller chip110, a plurality of demultiplexers120[1]-120[X], a plurality of data lines DL[1]-DL[N] and a plurality of dummy lines DML[1]-DML[P]. The controller chip110is coupled to scan lines SL[1]-SL[M], demultiplexers120[1]-120[X] and dummy lines DML[1]-DML[P], wherein X, M and N are positive integers, and P is a positive integer less than or equal to N.

The dummy lines DML[1]-DML[P] are located above the data lines DL[1]-DL[N]. Reference in the present disclosure to a component being “above” another component means that the component is formed (e.g., vapor-deposited) sequentially after the other component on a substrate. In other words, on the substrate, the formation order of the metal layer where the dummy lines DML[1]-DML[P] are located is after the metal layer where the data lines DL[1]-DL[N] are located.

In some embodiments, the controller chip110may be implemented with a touch and display driver integration (TDDI) chip.

In some embodiments, as shown inFIG.1, the touch screen100further includes a plurality of pixel circuits PX. The pixel circuits PX are arranged into M pixel rows coupled to the scan lines SL[1]-SL[M] and N pixel columns coupled to the data lines DL[1]-DL[N].

The demultiplexers120[1]-120[X] each includes a plurality of switches121-123, wherein the switches121-123are respectively coupled to parts of the data lines DL[1]-DL[N]. Take the demultiplexer120[1] as an example, the switch121is coupled to the data line DL[1], the switch122is coupled to the data line DL[3], and the switch123is coupled to the data line DL[5].

It should be noted that the quantity of the switches121-123in each of the demultiplexers120[1]-120[X] and the connection relationship between the switches121-123and the data lines DL[1]-DL[N] inFIG.1are only an example, and are not intended to limit the present disclosure. The other quantity of the switches and the other connection relationship between the switches and the data lines DL[1]-DL[N] are within the scope of the present disclosure.

In some embodiments, as shown inFIG.2, the first ends of the dummy lines DML[1]-DML[P] are coupled to each other, the second ends of the dummy lines DML[1]-DML[P] are coupled to a node N1, and the node N1is coupled to the controller chip110. In other embodiments, the first ends of the dummy lines DML[1]-DML[P] are coupled to each other, but the second ends of the dummy lines DML[1]-DML[P] are respectively coupled to a plurality of pins (not shown inFIG.2) of the controller chip110instead of being coupled to each other.

In some embodiments, as shown inFIG.2, the touch screen100further includes a plurality of touch electrodes TE. The touch electrodes TE are arranged in P touch electrode columns, and the P touch electrode columns and the dummy lines DML[1]-DML[P] are alternately arranged in a way that one touch electrode column and one dummy line alternate with each other.

Please refer toFIG.1andFIG.2together. For each demultiplexer, the data line coupled to one of the switches121-123corresponds to one of the dummy lines DML[1]-DML[P] in the vertical direction. For example, as shown inFIG.2, the data line DL[5] coupled to the switch123of the demultiplexer120[1] corresponds to the dummy line DML[3] in the vertical direction. For another example, as shown inFIG.2, the data line DL[2] coupled to the switch123of the demultiplexer120[2] corresponds to the dummy line DML[2] in the vertical direction, and so on.

In some embodiments, “corresponding to each other in the vertical direction” means that a dummy line and its corresponding data line are located between two adjacent ones of the N pixel columns. For example, the dummy line DML[3] and the data line DL[5] are located between the fourth pixel column and the fifth pixel column (i.e., between the fourth column and the fifth column of the pixel circuit PX). In other embodiments, “corresponding to each other in the vertical direction” means that a vertical projection on a substrate (not shown) of a dummy line of the touch screen100at least partially overlaps a vertical projection on the substrate of a data line corresponding to the dummy line.

In practice, the controller chip110is configured to perform various operations in a display stage and a touch stage. In the display stage, the controller chip110is configured to transmit switch signals SW1-SW3to the demultiplexers120[1]-120[X], so as to sequentially turn on the switches121-123, and then transmit display data to the data lines DL[1]-DL[N]. For example, when the switch signal SW1is changed from a disabled voltage level to an enabled voltage level, the switch121is turned on, so that the controller chip110can transmit the display data to the data lines DL[1], DL[4], . . . , DL[N−5] and DL[N−2]. In some embodiments, in the display stage, the controller chip110is configured to transmit scan signals G1-GM to the scan lines SL[1]-SL[M] respectively, so as to sequentially switch the scan lines SL[1]-SL[M] to the enabled voltage level or to the disabled voltage level. For example, in the display stage, when the scan signal G1is changed from the disabled voltage level to the enabled voltage level, the scan line SL[1] will be switched from the disabled voltage level to the enabled voltage level to drive the pixel circuit PX to receive the display data from the data lines DL[1]-DL[N].

In addition, in the display stage, the controller chip110is further configured to transmit the common voltage VCOM to the dummy lines DML[1]-DML[P]. According to the common voltage VCOM and the display data, the pixel circuit PX can display specific brightness. For example, in some embodiments, the pixel circuit PX can be implemented with a liquid crystal pixel circuit, the dummy lines DML[1]-DML[P] can act as one side of the electrodes of the liquid crystal capacitor, and the another side of the electrodes of the liquid crystal capacitor is used to receive the display data.

In some embodiments, in the touch stage, the controller chip110is configured to set the dummy lines DML[1]-DML[P] to a touch voltage for touch sensing. The dummy lines DML[1]-DML[P] with the touch voltage are configured to prevent external magnetic field from interfering with the touch electrodes TE, prevent the touch electrodes TE of different columns from interfering with each other, and assist in detecting the lateral movement of the user's finger. In some embodiments, in the touch stage, the controller chip110is further configured to turn off the switches121-123.

In practice, when the scan lines SL[1]-SL[M] are in the enabled voltage level, when the switch signals SW1-SW3are changed from the enabled voltage level to the disabled voltage level, the data lines DL[1]-DL[N] will not receive the display data from the controller chip110, but the capacitor of the pixel circuit PX is still electrically connected to the data line at this time. However, the voltage on the dummy lines at this time may have deviated from the common voltage VCOM due to the display data and are gradually recovering to the common voltage VCOM, thus the dummy lines will be coupled to the data lines corresponding to each other in the vertical direction, resulting in unstable voltage levels on the data lines, thereby affecting the brightness of the pixel circuit PX.

With the signal control method disclosed in the present disclosure, the coupling problem between the dummy lines and the data lines can be solved when the controller chip110transmits the scan signals G1-GM and the switch signals SW1-SW3to the scan lines SL[1]-SL[M] and the switches121-123with specific timing. The timing relationship between the scan signals G1-GM and the switch signals SW1-SW3will be described in detail in paragraphs below.

FIG.3A-3Bare timing diagrams of scan signals G1-G3and switch signals SW1-SW3in accordance with some embodiments of the present disclosure. Please refer toFIG.3Afirst, in some embodiments, the switch signals SW1-SW3are sequentially switched to the enabled voltage level when the scan signals G1-G3are in the enabled voltage level (i.e., the period when the scan lines SL[1]-SL[3] are in the enabled voltage level). For example, when the scan signal G1is in the enabled voltage level (i.e., the scan line SL[1] is in the enabled voltage level), the switch signals SW1-SW3are sequentially switched to the enabled voltage level, thus the switches121-123will turn on sequentially. Then, when the scan signal G2is in the enabled voltage level (i.e., the scan line SL[2] is in the enabled voltage level), the switch signals SW1-SW3are switched to the enabled voltage level in sequence again, thus the switches121-123will turn on again sequentially.

Since the switch signals SW1-SW3have the same waveform when each of the scanning signals G1-GM is in the enabled voltage level, and the demultiplexers120[1]-120[X] have similar operations, for the sake of brevity, the following only describes the timing relationship among the switch signals SW1-SW3, the scan signal G1and the scan signal G2with the demultiplexers120[1], and the rest can be deduced by analogy.

In the embodiment shown inFIG.3A, the data line coupled to each switch123corresponds to one of the dummy lines DML[1]-DML[P] in the vertical direction. For example, please refer toFIG.2again, the data line DL[2] coupled to the switch123of the demultiplexer120[2] corresponds to the dummy line DML[2] in the vertical direction; the data line DL[5] coupled to the switch123of the demultiplexer120[1] corresponds to the dummy line DML[3] in the vertical direction.

In the embodiment shown inFIG.3A, when the scan line is in the enabled voltage level, the switch signal SW3used to control the switch123is the last one of the switch signals SW1-SW3to be switched to the enabled voltage level. In other words, in this embodiment, when the scan line is in the enabled voltage level, the switch123is turned on after the switches121and122are turned on.

In addition, in the embodiment shown inFIG.3A, the pulse width of the switch signal SW3is greater than or equal to the pulse width of the switch signals SW1and SW2. For example, the switch signal SW3remains at the enabled voltage level after the scan signal G1is switched to the disabled voltage level, and is switched to the disabled voltage level before the scan signal G2is switched to the enabled voltage level (i.e., the periods P1and P2indicated by double arrows). Therefore, the switch123is turned off after the scan line SL[1] is switched to the disabled voltage level and before the scan line SL[2] is switched to the enabled voltage level. In some embodiments, the switch signal SW3is switched to the disabled voltage level when the scan signal G1is switched to the disabled voltage level, thus the switch123is turned off when the scan line SL[1] is switched to the disabled voltage level.

By delaying the time at which the switch123is turned off, the data lines DL[2], DL[5], . . . , DL[N−4] and DL[N−1] coupled to the switch123can continue receiving display data from the controller chip110after the scan lines SL[1]-SL[M] are switched to the disabled voltage level, which prevents the change of the common voltage VCOM on the dummy lines DML[1]-DML[P] from affecting the pixel circuit PX through the data lines DL[2], DL[5], . . . , DL[N−4] and DL[N−1], thus the touch screen100can display with uniform brightness.

Please refer toFIG.3B, in a certain touch screen (not shown) of the embodiment ofFIG.3B, each of the data lines coupled to the switches122corresponds to one of the dummy lines DML[1]-DML[P] in the vertical direction.

In the embodiment shown inFIG.3B, when the scan line is in the enabled voltage level, the switch signal SW2used to control the switch122is the last one of the switch signals SW1-SW3to be switched to the enabled voltage level. In other words, in this embodiment, when the scan line is in the enabled voltage level, the switch122is turned on after the switches121and123are turned on.

In addition, in the embodiment shown inFIG.3B, the pulse width of the switch signal SW2is greater than or equal to the pulse width of the switch signals SW1and SW3. For example, the switch signal SW2remains at the enabled voltage level after the scan signal G1is switched to the disabled voltage level, and is switched to the disabled voltage level before the scan signal G2is switched to the enabled voltage level (i.e., the periods P1and P2indicated by double arrows). Therefore, the switch122is turned off after the scan line SL[1] is switched to the disabled voltage level and before the scan line SL[2] is switched to the enabled voltage level. In some embodiments, the switch signal SW2is switched to the disabled voltage level when the scan signal G1is switched to the disabled voltage level, thus the switch122is turned off when the scan line SL[1] is switched to the disabled voltage level.

In conclusion, by designating the switches coupled to the data lines corresponding to the dummy lines DML[1]-DML[P] in the vertical direction to be controlled by the same switch signal, and by designating this switch signal to be switched to the disabled voltage level later than the scan signal, the brightness of the pixel circuit PX can avoid being affected by the change of the common voltage VCOM on the dummy lines DML[1]-DML[P].

FIG.4is a flowchart of signal control method400in accordance with some embodiments of the present disclosure. The signal control method400includes steps410-430of the display stage and steps440-450of the touch stage. In the step410of the display stage, the controller chip110sequentially switches the scan lines SL[1]-SL[M] to the enabled voltage level.

In the step420of the display stage, when one of the scan lines SL[1]-SL[M] (e.g., scan line G1) is in the enabled voltage level, the controller chip110sequentially turns on the switches121-123to transmit display data to the data lines DL[1]-DL[N], so as to control the brightness of the pixel circuit PX.

In the step430of the display stage, the controller chip110transmits the common voltage VCOM to the dummy lines DML[1]-DML[P] to control the brightness of the pixel circuit PX. In some embodiments, the switch123of the switches121-123is coupled to the data line DL[2], and the data line DL[2] corresponds to the dummy line DML[2] in the vertical direction. When the aforementioned scan line (e.g., the scan line G1) is in the enabled voltage level, the switch123is turned on after the switches121-122are turned on.

In the step440of the touch stage, the controller chip110sets the dummy lines DML[1]-DML[P] to the touch voltage for touch sensing.

In the step450of the touch stage, the controller chip110switches the switch signals SW1-SW3to the disabled voltage level to turn off the switches121-123.

It should be noted that the execution order of the various steps inFIG.4is only an example, and is not intended to limit the present disclosure. The other execution order of the various steps is within the scope of the present disclosure. For example, in some embodiments, steps420and430of the display stage may be performed simultaneously or in a reverse execution order. In other embodiments, steps440and450of the touch stage may be performed simultaneously or in a reverse execution order.

The signal control method400, controller chip110and touch screen100disclosed in present disclosure can reduce the uneven brightness of the screen caused by the coupling between the dummy lines and their corresponding data lines by adjusting the timing relationship of the switching signals SW1-SW3transmitted to the switches121-123.

Certain terms are used in the description and claim to refer to particular elements. However, it should be understood by those skilled in the art that the same elements may be referred to by different terms. The description and the claims do not take the difference in name as a way of distinguishing elements, but take the difference in function of the elements as a basis for distinguishing. The term “comprising” mentioned in the description and the claims is an open-ended term, so it should be interpreted as “including but not limited to”. In addition, the term “coupled” herein includes any direct and indirect means of connection. Therefore, if it is described in the description and the claims that the first element is coupled to the second element, it means that the first element may be directly connected to the second element through electrical connection or signal connection such as wireless transmission or optical transmission, or through other elements or connections.

As used herein, the term “and/or” includes any combination of one or more of the mentioned elements. Unless otherwise specified in the description, any term in the singular also includes the meaning in the plural.

The above are preferred embodiments of the present disclosure, and various modifications and equivalent changes may be made to the structure of the present disclosure without departing from the scope or spirit of the present disclosure. In view of the foregoing, it is intended that the present disclosure cover modifications and variations of this invention provided they fall within the scope of the following claims.