1. Field of the Invention
The present invention relates to a scanning method for a touch panel.
2. Description of the Related Art
Touch panels are widely applied in a variety of fields such as home appliances, communication devices and electronic information devices. The touch panel is often applied in input interfaces of personal digital assistants (PDAs), electronic products and game consoles. The current trend of integrating a touch panel and a display allows a user to select an icon displayed on the panel by using a finger or a touch pen, so that the PDA, the electric product, or the game console executes a desired function. The touch panel may also be applied in a public information inquiry system, so that the user can operate the system more efficiently.
In order to effectively detect a correct position at which the user touches the panel, multiple technologies of the touch panel have been developed. For example, the touch panel may be designed as a capacitive touch panel, which is based on the positioning principle of judging a touch position according to a change of capacitance of a sensing grid embedded in the touch panel. In addition to the capacitive touch panel, other touch panels based on different sensing principles include resistive touch panels, optical touch panels and surface acoustic wave touch panels.
During operation, the first multiplex selector 2622 selects one or more sensing lines from the X-directional sensing lines X1 to Xm, or selects one or more sensing lines from the Y-directional sensing lines Y1 to Yn, so as to select a first induced voltage. Meanwhile, the second multiplex selector 2624 selects one or more sensing lines that are not selected by the first multiplex selector 2622 from the X-directional sensing lines X1 to Xm, or selects one or more sensing lines that are not selected by the first multiplex selector 2622 from the Y-directional sensing lines Y1 to Yn, so as to select a second induced voltage. The first and second induced voltages are generated respectively by a mutual capacitor inducing an excitation signal. The first and second induced voltages are input into the differential detection module 264. The values of the induced voltages change as a user touches the mutual capacitors, so that a touch position of the user can be acquired by detecting differences between the induced voltages.
The touch panel 10 in
Therefore, it is necessary to provide a scanning method for a touch panel to solve the above problems.
The present invention discloses a scanning method for a touch panel. The touch panel includes a plurality of X-directional sensing lines and a plurality of Y-directional sensing lines. The X-directional sensing lines and the Y-directional sensing lines are arranged in a staggered manner, and a plurality of mutual capacitors are formed between every X-directional sensing line and every Y-directional sensing lines. The method includes selecting the number of sensing lines to be measured; selecting a plurality of first sensing lines from the X-directional sensing lines as a measurement channel according to the number of sensing lines; outputting a driving signal to other sensing lines excluding the first sensing lines during a first scan; detecting two first voltages on the measurement channel during the first scan; outputting the driving signal to the first sensing lines during a second scan; and detecting two second voltages on the shifted measurement channel according to the number of sensing lines to be measured during the second scan.
The present invention discloses another scanning method for a touch panel. The touch panel includes a plurality of X-directional sensing lines and a plurality of Y-directional sensing lines. The X-directional sensing lines and the Y-directional sensing lines are arranged in a staggered manner, and a plurality of mutual capacitors are formed between every X-directional sensing line and every Y-directional sensing line. The method includes the following steps: selecting the number of sensing lines to be measured; selecting a number of first sensing lines from the X-directional sensing lines as a measurement channel according to the number of sensing lines; outputting a driving signal to the Y-directional sensing lines and floating other sensing lines of the X-directional sensing lines during a first scan; detecting two first voltages on the measurement channel during the first scan; floating the first sensing lines during a second scan; and detecting two second voltages on the shifted measurement channel according to the number of sensing lines to be measured during the second scan.
The present invention discloses a touch input device. The touch input device includes a touch panel and a panel driving circuit configured to drive the touch panel. The touch panel includes a plurality of X-directional sensing lines and a plurality of Y-directional sensing lines. The X-directional sensing lines and the Y-directional sensing lines are arranged in a staggered manner, and a plurality of mutual capacitors are formed between every X-directional sensing line and every Y-directional sensing line. The panel driving circuit includes a selection circuit, a driving signal generation circuit, and a detection circuit. The selection circuit is configured to select and shift a measurement channel according to the number of sensing lines to be measured. The driving signal generation circuit is configured to output a driving signal to other sensing lines excluding the measurement channel according to an output signal of the selection circuit. The detection circuit is configured to detect two voltages on the measurement channel.
The invention will be described according to the appended drawings in which:
The present invention is directed to a touch panel and a scanning method thereof. In order to make the present invention completely comprehensible, detailed steps and structures are provided in the following description. Obviously, implementation of the present invention does not limit special details known by persons skilled in the art. In addition, known structures and steps are not described in details, so as not to limit the present invention unnecessarily. Preferred embodiments of the present invention will be described below in detail. However, in addition to the detailed description, the present invention may also be widely implemented in other embodiments. The scope of the present invention is not limited to the detailed description, and is defined by the claims.
In order to illustrate a scanning method of the present invention more smoothly, a touch input device executing the method of the present invention is first described below.
In this embodiment, the touch panel 32 includes a plurality of X-directional sensing lines X1 to X10 and a plurality of Y-directional sensing lines Y1 to Y10. The X-directional sensing lines X1 to X10 and the Y-directional sensing lines Y1 to Y10 are embedded in different layers of the touch panel 32. Referring to
The clock generation circuit 34 generates a clock signal clk to the driving signal generation circuit 36. The driving signal generation circuit 36 generates a driving signal DP to the X-directional sensing lines X1 to X10 and the Y-directional sensing lines Y1 to Y10 according to the clock signal clk. The driving signal DP may be, but is not limited to, a square wave driving signal, a triangular wave driving signal or a sine wave driving signal.
The first multiplex selector 4222 is configured to select one or more sensing lines from the X-directional sensing lines X1 to X10, or to select one or more sensing lines from the Y-directional sensing lines Y1 to Y10, so as to select a first induced voltage. The second multiplex selector 4224 is configured to select one or more sensing lines that are not selected by the first multiplex selector 4222 from the X-directional sensing lines X1 to X10, or to select one or more sensing lines that are not selected by the first multiplex selector 4222 from the Y-directional sensing lines to select a second induced voltage. The first and second induced voltages are input into the differential detection module 424. When an intersection of the X-directional sensing lines X1 to X10 and the Y-directional sensing lines Y1 to Y10 is touched, a mutual capacitance value changes, so that values of the induced voltages change. According to an output result of the differential detection module 424, a position touched by a user is acquired.
In Step S40, the number of sensing lines to be measured is selected. The number of sensing lines is an integer larger than or equal to 2.
Next, during the second scan, the initial measurement channel shifts to the right to form a new measurement channel, that is, the sensing lines X3 and X4. Therefore, the driving signal generation circuit 36 outputs the driving signal DP to other sensing lines excluding the sensing lines X3 and X4. During the second scan, a voltage on the sensing line X3 may be selected by the first multiplex selector 4222 to be transmitted to the first input end R of the differential detection module 424. Meanwhile, a voltage on the sensing line X4 may be selected by the second multiplex selector 4224 to be transmitted to the second input end S of the differential detection module 424. The differential detection module 424 generates the touch sensing signal Sout according to the voltage values at the two input ends.
Similarly, in other scanning sequences, the measurement channel shifts to the right in sequence. The driving signal DP is input into the sensing lines excluding the measurement channel. Under a coupling effect of the mutual capacitor, the driving signal DP is coupled to nodes of the measurement channel. If a user touches the nodes, a capacitance value of the mutual capacitor changes, thereby causing the voltage to change. By detecting the change of the voltages, a touched position on the touch panel 32 can be acquired. In the present embodiment, a previous state of the measurement channel set each time is always a driven state. Therefore, during each scan, initial voltage values of the nodes of the measurement channel are the same, and a steady-state voltage value thereof can truly reflect a change of the capacitance value of the mutual capacitor.
In Step S60, the number of sensing lines to be measured is first selected. The number of sensing lines is an integer larger than or equal to 2.
During the second scan, the initial measurement channel shifts to the right to form a new measurement channel, that is, the sensing lines X3 and X4. Therefore, the driving signal generation circuit 36 outputs the driving signal DP to the Y-directional sensing lines Y1 to Y10, and the sensing lines excluding the sensing lines X3 and X4 are in a floated state. During the second scan, a voltage on the sensing line X3 may be selected by the first multiplex selector 4222 to be transmitted to the first input end R of the differential detection module 424. Meanwhile, a voltage on the sensing line X4 may be selected by the second multiplex selector 4224 to be transmitted to the second input end S of the differential detection module 424. The differential detection module 424 generates the touch sensing signal Sout according to the voltage values at the two input ends.
Similarly, in other scanning sequences the measurement channel shifts to the right in sequence. The driving signal DP is input into the sensing lines excluding the measurement channel, or the sensing lines excluding the measurement channel are kept in a floated state. Under a coupling effect of the mutual capacitor, the driving signal is coupled to nodes of the measurement channel. If a user touches the nodes, a capacitance value of the mutual capacitor changes, thereby causing the voltage to change. By detecting the change of the voltages, a touched position on the touch panel 32 can be acquired. In the present embodiment, a previous state of the measurement channel set each time is always a floated state. Therefore, during each scan, initial voltage values of the nodes of the measurement channel are the same, and a steady-state voltage value thereof can truly reflect a change of the capacitance value of the mutual capacitor.
Referring to
In the touch panel implemented according to the scanning method of the present invention, the minimum number of X-directional sensing lines or the minimum number of Y-directional sensing lines may depend on the number of sensing lines to be measured. In a preferred embodiment, the minimum number of X-directional sensing lines or the minimum number of Y-directional sensing lines is determined according to the following equation (1):
Num=4×NSET−2 (1)
where Num represents the minimum number of X-directional sensing lines or the minimum number of Y-directional sensing lines, and NSET represents the set number of the initial measurement channel. For example, as shown in
Although the technical contents and features of the present invention are described above, various replacements and modifications can be made by persons skilled in the art based on the teachings and invention of the present invention without departing from the spirit thereof. Therefore, the scope of the present invention is not limited to the described embodiments, but covers various replacements and modifications that do not depart from the present invention as defined by the appended claims.
Number | Date | Country | Kind |
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099127043 | Aug 2010 | TW | national |