The present invention relates to a touch panel that detects contact or approach of a finger, a stylus, or the like to a detection surface, and to a display device having such a touch panel function in the display part thereof.
A touch panel that detects that a finger, a stylus, or the like of a user has come into contact with or approached a detection surface is known. In recent years, electronic devices in which touch panel functions (also referred to as touch sensor functions) that can freely perform various functions just by having a stylus or the like touch the display screen are provided in a liquid crystal display element such as a liquid crystal display screen are starting to become widely used. Such a touch panel is formed onto a display panel, and by displaying various types of buttons on the display screen as images, it is possible to realize data input substituting these displayed buttons for normal buttons. Thus, when applying such a touch panel to a miniature mobile device, it is possible to have the display and buttons share a common space, thus presenting great advantages such as being able to increase the size of the display screen, decreasing the amount of space dedicated to control parts, or reducing the number of parts.
Additionally, a technique is known in which a touch panel shares some of the structure of the display part. For example, a configuration is known in which pixel electrodes or an opposite electrode for liquid crystal display, or the source bus lines double as one of the detection electrodes (detection lines) of a capacitance detection type touch panel. If the configuration is shared in this manner, it is also possible to attain the advantage that the device can be made thin.
However, if the detection electrode doubles as an electrode for display in this manner, the display driving frequency and the detection driving frequency match due to functional reasons. As a result, even if an attempt is made to raise the detection driving frequency because the detection speed is low and the responsiveness to data input is bad, there is a problem that it is not possible to freely change the detection driving frequency due to restrictions in the display driving frequency.
Patent Document 1 discloses a contact detection device in which the detection speed is improved without raising the detection driving frequency. As shown in
Also, as shown in
However, with the configuration of Patent Document 1, if objects to be detected come into contact with (approach) the same line in different contact response part regions, the electrical changes generated in the respective regions cancel each other out, resulting in no output.
In order to avoid this situation, a possible solution is to rely on instantaneous output change resulting from a time difference between the two contact (approach) points. However, this only works when the contact speed (i.e. the time difference) is sufficiently slower than the sensing speed, and if active sensing speed is slow (30 ms to a second, for example) such as when multiple unit output changes accumulate and are used as main output, when reactivating after standby, or the like, then there is a possibility of glitches such as non-detection occurring.
The present invention takes into account the above-mentioned problems, and an object thereof is to provide a highly reliable touch panel in which glitches such as non-detection do not occur, and a display device provided therewith.
The inventors of the present invention have found that the above-mentioned object can be attained by mitigating the induction of an inactive charge among parasitic capacitance formed between the driver electrodes and the detection electrodes.
Thus, in order to solve the above-mentioned problems, the touch panel according to the present invention is
a touch panel that detects contact or approach of an object to be detected to a detection surface on the basis of a change in amount of an electric charge induced on a detection electrode by applying a drive signal to a driver electrode, the touch panel including a complementary electrode that can form parasitic capacitance along with the detection electrode,
wherein the complementary electrode has a configuration such that a complementary signal having a different phase than the drive signal is applied to the complementary electrode when the drive signal is applied to the driver electrode, an amplitude ΔVcm of the complementary signal satisfying a formula below:
ΔVcm=−ΔVdr×(Cfo+Ccr)/Ccm
where, in the formula, ΔVdr represents an amplitude of the drive signal, Cfo represents a parasitic capacitance between the driver electrode and the detection electrode corresponding to a capacitance component that is not affected by the object to be detected among fringe capacitances, Ccr represents a parasitic capacitance between the driver electrode and the detection electrode corresponding to a capacitance component that is not affected by the object to be detected among cross capacitances, and Ccm represents a parasitic capacitance formed between the complementary electrode and the detection electrode.
According to the configuration above, by providing a complementary electrode, it is possible to form between the complementary electrode and the detection electrode a parasitic capacitance corresponding to capacitance component that does not affect detection, among the parasitic capacitance formed between the driver electrode and the detection electrode.
Specifically, (Cfo+Ccr) in the formula above represents a parasitic capacitance (Cfo) corresponding to a capacitance component between the driver electrode and the detection electrode that is not affected by an object to be detected among fringe capacitances being added to a parasitic capacitance (Ccr) corresponding to a capacitance component between the driver electrode and the detection electrode that is not affected by an object to be detected among cross capacitances. By multiplying this by (−ΔVdr), the resulting value corresponds to inactive charge that is formed regardless of whether or not an object to be detected is in contact or approaches the detection surface, and thus, by dividing this value by the parasitic capacitance (Ccm) formed between the complementary electrode and the detection electrode, it is possible to calculate the amplitude (ΔVcm) of the complementary signal. At the time of detection, by applying the complementary signal having this amplitude (ΔVcm) to the complementary electrode, of the charge induced on the detection electrode, the charge that is not affected by the object to be detected, or in other words, the inactive charge can be minimized.
Also, even if objects to be detected are in contact with (approach) the detection surface on the same line, the electrical changes do not cancel each other out unlike the conventional configuration. Thus, glitches such as non-detection do not occur.
Therefore, according to the configuration of the present invention, it is possible to provide a highly reliable touch panel in which glitches such as non-detection do not occur.
Fringe capacitance refers to capacitance formed between electrodes in the same layer, while cross capacitance refers to capacitance formed between electrodes in different layers from each other.
The present invention also includes a display device provided with the above-mentioned touch panel.
As stated above, a touch panel according to the present invention is
a touch panel that detects contact or approach of an object to be detected to a detection surface on the basis of a change in amount of an electric charge induced on a detection electrode by applying a drive signal to a driver electrode, the touch panel including a complementary electrode that can form parasitic capacitance along with the detection electrode,
wherein the driver electrode and the detection electrode are, in portions thereof, in different layers from each other, and
wherein the complementary electrode has a configuration such that a complementary signal having a different amplitude than the drive signal is applied to the complementary electrode when the drive signal is applied to the driver electrode, an amplitude ΔVcm of the complementary signal satisfying a formula below:
ΔVcm=−ΔVdr×(Cfo+Ccr)/Ccm
where, in the formula, ΔVdr represents an amplitude of the drive signal, Cfo represents a parasitic capacitance between the driver electrode and the detection electrode corresponding to a capacitance component that is not affected by the object to be detected among fringe capacitances, Ccr represents a parasitic capacitance between the driver electrode and the detection electrode corresponding to a capacitance component that is not affected by the object to be detected among cross capacitances, and Ccm represents a parasitic capacitance formed between the complementary electrode and the detection electrode.
Also, the display device according to the present invention includes the above-mentioned touch panel.
According to the configuration of the present invention, it is possible to provide a highly reliable touch panel in which glitches such as non-detection do not occur.
An embodiment of the present invention will be explained below with reference to
First, an embodiment of a touch panel of the present invention will be explained, and then, an embodiment of a display device of the present invention will be explained.
The touch panel of the present embodiment detects that a finger, a stylus, or the like of a user has come into contact with or approached a detection surface. Thus, as shown in
A specific configuration of the touch panel region 1 will be described with reference to the touch panel region 1 shown in
The portions in
As shown in
As shown in
The driver electrode parts 21 and the detection electrode parts 31, as shown in
The driver electrode parts 21 are respectively quadrilaterals. The plurality of driver electrode parts 21 are aligned along the row direction such that one set of opposite sides in each quadrilateral extends in one line in the row direction, and the driver electrode parts 21 that are aligned in the row direction are electrically connected to each other by the first bridge parts 22. There are a plurality of such rows, which are aligned in the column direction, parallel to each other. The first bridge parts 22 electrically connect driver electrode parts 21 aligned in the row direction. The driver electrode parts 21 and the first bridge parts 22 are described later with reference to
The detection electrode parts 31 are, in general, the same shape as the driver electrode parts 21, and are respectively quadrilaterals. The plurality of detection electrode parts 31 are aligned along the column direction such that one set of opposite sides in each quadrilateral extends in one line in the column direction, and the detection electrode parts 31 that are aligned in the column direction are electrically connected to each other by the second bridge parts 32. There are a plurality of such columns, which are aligned in the row direction, parallel to each other.
The driver electrode parts 21 and the detection electrode parts 31 are disposed in an alternating fashion in the row direction and the column direction, respectively. Specifically, the driver electrode parts 21, as described above, are in the same layer as the detection electrode parts 31, and as shown in
The second bridge parts 32 are disposed in the same layer so as to separate driver electrode parts 21 adjacent to each other in the row direction.
Here, the shape of the driver electrode parts and the shape of the detection electrode parts as shown in
a) is an arrow cross-sectional view of the touch panel 10 along the section line A-A′ shown in
As shown in
The shield 13 protects the touch panel 10 from external shocks, and protects the touch panel from external electromagnetic waves that interfere with the touch panel function, or in other words, the touch sensor function. The shield 13 can be made of a conventional material, and disposed using a conventional method.
The touch sensor function of the touch panel 10 of the present embodiment will be described. In the position shown in
When viewing the parasitic capacitance in detail with reference to
In other words, between the driver electrode parts 21 and the detection electrode parts 31 in the same layer as each other, there is both a parasitic capacitance Cfo that is not affected by the object to be detected, and a parasitic capacitance Cfs that is affected by the object to be detected.
Also, the parasitic capacitance Cfo is formed between the driver electrode parts 21 and the second bridge part 32 in the same layer shown in
As shown in
As for other parasitic capacitance, a parasitic capacitance Ccm_cr formed between the complementary electrode 4 to be described later and the detection electrode 3 is also present.
To summarize,
Cfo is a component of the fringe capacitance between the driver electrodes and the detection electrodes that is not affected by an object to be detected,
Cfs is a component of the fringe capacitance between the driver electrodes and the detection electrodes that is affected by an object to be detected,
Ccr is a component of the cross capacitance between the driver electrodes and the detection electrodes that is affected by an object to be detected, and
Ccm_cr is a cross capacitance between the detection electrodes and the complementary electrodes. Here, fringe capacitance refers to capacitance formed within the same layer, and cross capacitance refers to capacitance formed in different layers.
To reiterate the explanation of the principle of the touch sensor function, if the capacitance between the driver electrodes and the detection electrodes is Cf, then an electrical charge Q induced on the detection electrode if the driver electrode is driven once at ΔVdr is expressed in the following formula:
Q=ΔVdr×Cf.
Based on
in the non-contact state, Cf=Cfo+Cfs+Ccr, and
in the contact state, Cf=Cfo+Ccr.
Where the non-contact state induced charge is Q and the contact state induced charge is Q@Touch,
Q=ΔVdr×(Cfo+Cfs+Ccr), and
Q@Touch=ΔVdr×(Cfo+Ccr),
and a charge Qsig representing the detected signal is such that
Qsig=Q−Q@Touch=ΔVdr×Cfs.
Thus, the circuit receiving the induced charge (integrator or decision circuit) uses, for determination, the width of the detected signal charge Qsig upon obtaining a sufficient width to be able to receive a non-contact state induced charge Q as an input dynamic range.
In
Based on
Rd=Cfs/((Cfo+Cfs+Ccr)+αCj/ΔVdr).
In
In order to attain this object, in the present embodiment, as shown in
The complementary electrodes 4 extend in parallel with the driver electrodes 2 (row direction) along the extension direction of the driver electrodes 2 in the touch panel region 1 shown in
As for the complementary electrode 4 disposed in this manner, where the parasitic capacitance between the complementary electrode and the detection electrode is Ccm (=Ccm_cr), and the complementary signal amplitude is ΔVcm, the amount of charge induced when the complementary electrode and the driver electrode are driven simultaneously is as follows:
Q=ΔVdr×(Cfo+Cfs+Ccr)+ΔVcm×Ccm, and
Q@Touch=ΔVdr×(Cfo+Ccr)+ΔVcm×Ccm.
Here, by setting ΔVcm and Ccm (=Ccm_cr) such that
ΔVcm×Ccm≈−ΔVdr×(Cfo+Ccr),
it is possible to mitigate the occurrence of charge that does not contribute to determination.
In other words, the configuration is such that when applying the drive signal to the driver electrodes 2, a complementary signal at a different phase from the drive signal is applied to the complementary electrodes 4, and the amplitude (ΔVcm) of the complementary signal satisfies the following formula:
ΔVcm=−ΔVdr×(Cfo+Ccr)/Ccm
Cfo+Ccr in the formula corresponds to Cf−Cfs, and to a capacitance component unnecessary for detection.
The complementary signal is generated by a complementary signal generating circuit, which is not shown in the drawings, included in the touch panel, and a drive signal is inputted to the complementary signal generating circuit. The complementary signal generating circuit reverses the inputted drive signal, thus generating the complementary signal. Thus, an appropriate complementary signal based on the drive signal is generated and applied to the complementary electrodes.
In order to fulfill the formula above, when considering a calibration step for when the touch panel is shipped, for example, one method is to bring a conductive plate into contact so as to cover the touch panel (Cfs=0), and set ΔVcm such that the detection electrode signal output in relation to the driver electrode signal at this time is at a minimum. An adjustment method at this time is to set the Rf in the complementary signal generating mechanism shown in
In the top two graphs of
Qsig0=Q−Q@Touch=ΔVdr×Cfs.
This represents the difference between the amount of charge induced on the detection electrode when there are no objects to be detected, and the amount of charge induced on the detection electrode when an object to be detected has come into contact with (approached) the detection electrode.
The top two graphs of
By applying complementary signals shown in the middle two graphs of
The positions indicated with (i) in the bottom two graphs of
The top two graphs and the bottom two graphs of
Q1<Q0,
Qsig1≈Qsig0, and
Qsig1/Q1>Qsig0/Q0.
Thus, in the touch panel 10 of the present invention, by providing complementary electrodes 4,
(1) it is possible to reduce the input dynamic range of the charge receiving circuit depending on the total signal amount, thereby attaining low power consumption by performing low voltage driving, and
(2) it is possible to improve signal resolution (resolution). As an example, if the total signal amount has a 12-bit resolution, then if Qsig1/Q1=½ and Qsig0/Q0=¼, then the resolution of Qsig1 is 11-bit and the resolution of Qsig0 is 10-bit.
Next, a display device to which the above-mentioned touch panel is installed will be described.
Here, as an example of a display device, first, a configuration of a general liquid crystal display device will be described with reference to
The liquid crystal display device 170 has a configuration in which a plurality of image signal lines SL and a plurality of scanning signal lines GL intersect each other, and includes a driver 173 in a frame 172 of the liquid crystal display device adjacent to the display region 171, and a flexible substrate 174 provided with lines to connect to the power source and the like. In the display region 171, pixels 175 are provided at the intersections between the image signal lines SL and the scanning signal lines GL.
Details of the display region 171 will be described with reference to
The display region 171 includes pixel electrodes 180 arranged in a matrix, a common electrode 181 disposed opposite to the pixel electrodes 180 with a liquid crystal layer therebetween, auxiliary capacitance lines 182 that form an auxiliary capacitance Cs between the pixel electrodes 180 and the auxiliary capacitance lines 182, and switching elements 183 connected to the image signal lines SL and the scanning signal lines GL and performing switching on the pixel electrodes 180.
The liquid crystal display device 170 is an active matrix liquid crystal display device that uses a drive method in which, when each of the switching elements 183 is in the on period, an image signal voltage with its signal voltage polarity reversed every field period of the display screen is applied to each of the pixel electrodes 180, and in the off period of the switching element 183, a modulated signal in the opposite direction is applied to the auxiliary capacitance lines 182 every field period, thereby changing the potential of the pixel electrodes 180. This allows the change in potential and the pixel signal voltage to overlap or cancel each other out, and this voltage is applied to the liquid crystal layer. A circuit configuration of one pixel is shown in
In the display device of the present embodiment, a touch panel (function) is installed on the above-mentioned liquid crystal display device.
Specifically, touch panels can be broadly categorized as an on-cell type or an in-cell type. On-cell type is a type in which a touch panel is attached to the surface of a liquid crystal display device such as that mentioned above. In-cell type refers to a type in which a touch panel function is installed in a liquid crystal display device such as that mentioned above, and in which the touch panel uses some of the electrode configurations used in the display device.
Below, first, an on-cell type liquid crystal display device will be described.
The liquid crystal display device 90 shown in
The liquid crystal display part 70 has a pair of substrates with a liquid crystal layer therebetween, and on the rearmost surface, a first polarizing plate 71 is provided. This liquid crystal display part 70 has the configuration shown in
The touch panel part 80 has the configuration of the touch panel of
The touch panel part 80 is provided with a second polarizing plate 73 between the protective plate 12 and the various electrodes 81. The touch panel part 80 is also provided with a detection driver 82 that applies a voltage (signal) to the various electrodes 81.
In this manner, an on-cell type liquid crystal display device 90 of the present embodiment can detect that an object to be detected is in contact with or approaching a detection surface (surface of the protective plate 12) in the touch panel part 80 in a state in which images are displayed in the liquid crystal display part 70.
The above-mentioned on-cell type liquid crystal display device is one example and the present invention is not limited thereto; the present invention can be applied to various types of on cell-type liquid crystal display devices.
The present invention is not limited to a configuration in which various electrodes of the touch panel are formed on the substrate of the liquid crystal display part, and a configuration may be used in which the second polarizing plate is provided on the liquid crystal display part, and on the second polarizing plate, everything from the substrate 11 to the protective plate 12 shown in
Next, an in-cell type liquid crystal display device will be described.
As an example of a configuration of
The in-cell type liquid crystal display device is not limited to the configuration of
Below, a driving method will be described for an in-cell type, in which the common electrode for display is shared with the driver electrodes and the detection electrodes for the touch panel.
The display device according to the present embodiment can be applied as a display device with a touch sensor integrally incorporated therein. Besides this, the display device is suitable to various electronic devices that include touch sensor functionality. This display device can also be applied to personal computers and various portable devices such as mobile phones and laptop computers.
As stated above, according to the configuration of the touch panel 10 of the present embodiment, by disposing a complementary electrode 4, it is possible to form between the complementary electrode and the detection electrode a parasitic capacitance corresponding to a capacitance component that does not affect detection, among the parasitic capacitance formed between the driver electrode 2 and the detection electrode 3.
Specifically, in (Cfo+Ccr) in the above formula, a parasitic capacitance (Cfo) corresponding to a capacitance component that is not affected by the object to be detected among fringe capacitances between the driver electrode 2 and the detection electrode 3 is added to a parasitic capacitance (Ccr) corresponding to a capacitance component that is not affected by the object to be detected among cross capacitances between the driver electrode 2 and the detection electrode 3. By multiplying this value by (−ΔVdr), the resulting value corresponds to inactive charge that is generated regardless of whether or not an object to be detected is in contact with or approaches the detection surface, and thus, by dividing this value by the parasitic capacitance (Ccm) formed between the complementary electrode and the detection electrode, it is possible to calculate the amplitude (ΔVcm) of the complementary signal. At the time of detection, by applying the complementary signal having this amplitude (ΔVcm) to the complementary electrode 4, of the parasitic capacitance induced on the detection electrode, the charge that is not affected by the object to be detected, or in other words, the inactive charge can be minimized.
Also, even if objects to be detected are in contact with (approach) the detection surface on the same line, the electrical changes do not cancel each other out unlike the conventional configuration. Thus, glitches such as non-detection do not occur.
Therefore, according to the configuration of the present embodiment, it is possible to provide a highly reliable touch panel in which glitches such as non-detection do not occur.
Also, according to the present embodiment, the complementary electrodes and the driver electrodes have different shapes, and thus, it is possible to independently use optimal shapes to form the parasitic capacitance component necessary for each of the electrodes. For example, it is possible for the complementary electrode to have a shape that can achieve an optimal capacitance value (Cm) in order to minimize the inactive charge induced by the driver electrode on the detection electrode, and to have a shape that can minimize the parasitic capacitance component of the detection electrode that is affected by the object to be detected, and it is possible for the driver electrode to have a shape that can maximize the parasitic capacitance component that is affected by the object to be detected. As for the “different shapes,” the electrodes may have different widths.
Another embodiment according to the present invention is as described below with reference to
The difference between the touch panel of Embodiment 1 and the touch panel of the present embodiment is only that the position of the electrodes is different. Thus, only the position of the electrodes will be described below.
In the touch panel region of the present embodiment, as shown in
The first bridge parts 22 that connect the driver electrode parts 21′ with each other in the row direction extend along the row direction in the same layer as the driver electrode parts 21′ and the detection electrode parts 31. In other words, the detection electrode parts 31 aligned along the column direction are separated by the first bridge parts 22.
The first bridge parts 22 are constituted of a first bridge part 22a and a first bridge part 22b proximal to each other in the column direction. The first bridge part 22a and the first bridge part 22b are disposed between detection electrode parts 31 adjacent to each other in the column direction.
The first bridge part 22a and the first bridge part 22b are disposed between detection electrode parts 31 adjacent to each other in the column direction, and between the first bridge part 22a and the first bridge part 22b, a complementary electrode 4 is formed.
The driver electrode parts 21′ differ from those of Embodiment 1 in having a triangular shape. The triangular driver electrode parts 21′ are disposed in a substantially triangular space formed by dividing a substantially quadrilateral space formed in the same layer as the detection electrode part 31 by the arrangement of quadrilateral detection electrode parts 31 in
The first bridge part 22a and the first bridge part 22b may be driven separately or driven together.
a) is an arrow cross-sectional view of the touch panel 10′ along the section line A-A′ shown in
Parasitic capacitances Cfs, Cfo, Ccr, and Ccm_cr respectively shown in
In other words, the configuration is such that when applying the drive signal to the driver electrodes 2, a complementary signal at a different phase from the drive signal is applied to the complementary electrodes 4, and the amplitude (ΔVcm) of the complementary signal satisfies the following formula:
ΔVcm=−ΔVdr×(Cfo+Ccr)/Ccm
and the complementary signal with the amplitude (ΔVcm) is applied to the complementary electrode 4.
Thus, as in Embodiment 1, a highly reliable touch panel in which glitches such as non-detection do not occur is attained.
The touch panel 10′ of the present embodiment can also be installed on a display device, as in Embodiment 1.
Another embodiment according to the present invention is as described below with reference to
The difference between the touch panel of Embodiment 1 and the touch panel of the present embodiment is only that the position of the electrodes is different. Thus, only the position of the electrodes will be described below.
In the touch panel region of the present embodiment, as shown in
The driver electrodes 2′ are not constituted of the driver electrode parts and the first bridge parts unlike Embodiment 1, but have an electrode line shape. Complementary electrodes 4 are the same as in Embodiment 1 and have an electrode line shape.
As shown in
The detection electrodes 3′ have intersections 50 with the complementary electrodes 4 that are wider in the row direction than intersections 60 with the driver electrodes 2′. With this configuration, the detection electrodes are made wider on the complementary electrodes, and block lines of electric force from the lower layer outside, thereby minimizing the capacitance component between the complementary electrodes and the detection electrodes being affected by the object to be detected.
a) is an arrow cross-sectional view of the touch panel 10″ along the line A-A′ shown in
Parasitic capacitances Cfs, Cfo, Ccr, and Ccm_cr respectively shown in
In other words, the configuration is such that when applying the drive signal to the driver electrodes 2, a complementary signal at a different phase from the drive signal is applied to the complementary electrodes 4, and the amplitude (ΔVcm) of the complementary signal satisfies the following formula:
ΔVcm=−ΔVdr×(Cfo+Ccr)/Ccm,
and the complementary signal with the amplitude (ΔVcm) is applied to the complementary electrode 4.
Thus, as in Embodiment 1, a highly reliable touch panel in which glitches such as non-detection do not occur is attained.
The touch panel 10″ of the present embodiment can also be installed on a display device, as in Embodiment 1.
In the touch panel 10″ of the present embodiment, the shape of overlap of the complementary electrodes and the detection electrodes is different from the shape of overlap of the driver electrodes and the detection electrodes. According to this, among the capacitance between the detection electrode and the driver electrode and between the detection electrode and the complementary electrode, the cross capacitance is not easily affected by the state of the detection surface, or in other words, whether or not an object to be detected as come into contact (approached), compared to the fringe capacitance. This allows an optimal capacitance value (Ccm) to be attained at the complementary electrode for minimizing the inactive charge induced on the detection electrode by the driver electrode, and is suited to minimizing the parasitic capacitance component in the detection electrode that is affected by an object to be detected. Thus, by having different shapes for overlapping portions, a more suitable complementary driving can be performed.
Another embodiment according to the present invention is as described below with reference to
In Embodiment 1 above, a complementary signal generating circuit to which a drive signal is to be inputted generates a complementary signal. The present embodiment, in addition to this, has an amplitude adjusting circuit that adjusts amplitude. This will be explained with reference to
a) is a drawing for describing a complementary signal generating mechanism in the present embodiment, and
As shown in
By providing such an amplitude adjusting circuit 42, even if a change is made that affects the parasitic capacitance component in the device, such as the shape of various electrodes and the layered structure in the panel, the same circuit can be used with appropriate conditions.
An appropriate complementary signal is generated by the amplitude adjusting circuit 42, and this generated complementary signal is applied to the complementary electrode 4 in the touch panel region (
The present invention is not limited to the embodiments above. Various modifications can be made to the present invention by those skilled in the art without departing from the scope specified by claims. That is, new embodiments can be obtained by combining technologies that were appropriately modified in the scope specified by claims. That is, the specific embodiments provided in the detailed description of the present invention section are merely for illustration of the technical contents of the present invention. The present invention shall not be narrowly interpreted by being limited to such specific examples. Various changes can be made within the spirit of the present invention and the scope as defined by the appended claims.
As stated above, a touch panel according to the present invention is a touch panel that detects contact or approach of an object to be detected to a detection surface on the basis of a change in amount of an electric charge induced on a detection electrode by applying a drive signal to a driver electrode, the touch panel including a complementary electrode that can form parasitic capacitance along with the detection electrode,
in which the complementary electrode has a configuration such that a complementary signal having a different phase than the drive signal is applied to the complementary electrode when the drive signal is applied to the driver electrode, an amplitude ΔVcm of the complementary signal satisfying a formula below:
ΔVcm=−ΔVdr×(Cfo+Ccr)/Ccm
where, in the formula, ΔVdr represents an amplitude of the drive signal, Cfo represents a parasitic capacitance between the driver electrode and the detection electrode corresponding to a capacitance component that is not affected by the object to be detected among fringe capacitances, Ccr represents a parasitic capacitance between the driver electrode and the detection electrode corresponding to a capacitance component that is not affected by the object to be detected among cross capacitances, and Ccm represents a parasitic capacitance formed between the complementary electrode and the detection electrode.
According to the configuration above, by providing a complementary electrode, it is possible to form between the complementary electrode and the detection electrode a parasitic capacitance corresponding to a capacitance component that does not affect detection, among the parasitic capacitance formed between the driver electrode and the detection electrode.
Specifically, (Cfo+Ccr) in the formula above represents a parasitic capacitance (Cfo) corresponding to a capacitance component that is not affected by an object to be detected among fringe capacitance between the driver electrode and the detection electrode being added to a parasitic capacitance (Ccr) corresponding to a capacitance component that is not affected by an object to be detected among cross capacitance between the driver electrode and the detection electrode. By multiplying this by (−ΔVdr), the resulting value corresponds to inactive charge that is generated regardless of whether or not an object to be detected is in contact or approaches the detection surface, and thus, by dividing this value by the parasitic capacitance (Ccm) formed between the complementary electrode and the detection electrode, it is possible to calculate the amplitude (ΔVcm) of the complementary signal. At the time of detection, by applying the complementary signal having this amplitude (ΔVcm) to the complementary electrode, of the charge induced on the detection electrode, the charge that is not affected by the object to be detected, or in other words, the inactive charge can be minimized.
Also, even if objects to be detected are in contact with (approach) the detection surface on the same line, the electrical changes do not cancel each other out unlike the conventional configuration. Thus, glitches such as non-detection do not occur.
Therefore, according to the configuration of the present invention, it is possible to provide a highly reliable touch panel in which glitches such as non-detection do not occur.
Fringe capacitance refers to capacitance formed between electrodes in the same layer, while cross capacitance refers to capacitance formed between electrodes in different layers from each other.
In addition to the configuration above, in the touch panel according to the present invention, it is preferable
that the complementary electrodes and the driver electrodes have different shapes.
According to this configuration, the complementary electrodes and the driver electrodes have different shapes, and thus, it is possible to independently use optimal shapes to form the parasitic capacitance component necessary for each of the electrodes. For example, it is possible for the complementary electrodes to have a shape that can attain an optimal capacitance value (Ccm) for minimizing the inactive charge induced by the driver electrode on the detection electrode and that can minimize the parasitic capacitance component of the detection electrode being affected by the object to be detected, and it is possible for the driver electrodes to have a shape by which it is possible to maximize the parasitic capacitance component that is affected by the object to be detected.
As for the “different shape,” the electrodes may have different widths.
In addition to the configuration above, it is preferable that the touch panel of the present invention
include a complementary signal generating circuit that generates the complementary signal when the drive signal is inputted thereto.
According to this configuration, an appropriate complementary signal can be applied to the complementary electrode based on the drive signal.
In addition to the configuration above, it is preferable that the touch panel of the present invention
include an adjusting circuit that adjusts an amplitude of the complementary signal when the complementary signal is inputted thereto.
According to this configuration, by providing an adjusting circuit that adjusts the amplitude of the complementary signal, it is possible to use the same circuits with appropriate conditions even if changes that affect the parasitic capacitance components in the device such as the shape of the various electrodes and the layered structure inside the panel are made.
In addition to the configuration above, in the touch panel according to the present invention, it is preferable
that a plurality of the driver electrodes extend along a row direction, and a plurality of the detection electrodes extend along the column direction so as to intersect with the driver electrodes,
that the complementary electrodes extend along an extension direction of the driver electrodes, and
that a shape of overlap between the complementary electrodes and the detection electrodes differ from a shape of overlap between the driver electrodes and the detection electrodes.
According to this configuration, among the capacitance between the detection electrode and the driver electrode and complementary electrode, the cross capacitance is not easily affected by the state of the detection surface, or in other words, whether or not an object to be detected as come into contact (approached), compared to the fringe capacitance. This allows an optimal capacitance value (Ccm) to be attained at the complementary electrode for minimizing the inactive charge induced on the detection electrode by the driver electrode, and is suited to minimizing the parasitic capacitance component in the detection electrode that is affected by an object to be detected. Thus, by having different shapes for overlapping portions, a more suitable complementary driving can be performed.
In addition to the configuration above, in the touch panel of the present invention it is preferable that the driver electrodes include a plurality of driver electrode parts interconnected by first bridge parts,
that the detection electrodes include a plurality of detection electrode parts interconnected by second bridge parts,
that the driver electrode parts and the detection electrode parts be in the same layer as each other, and
that either of the first bridge parts or the second bridge parts be in the same layer as the driver electrode parts and the detection electrode parts, with the other of the first bridge parts and the second bridge parts being in a layer different from the layer, and the complementary electrodes, at a portion thereof overlapping the detection electrodes, are in the same layer as whichever of the first bridge parts or the second bridge parts is in the layer different from driver electrode parts and the detection electrode parts.
According to this configuration, by forming the driver electrode parts and the detection electrode parts in the same layer, it is possible to efficiently form a capacitance component that is affected by the object to be detected, while by including the complementary electrodes in a different layer from the driver electrode parts and the detection electrode parts, it is possible to minimize the capacitance component that is affected by the object to be detected between the complementary electrodes and the detection electrodes. As in
In addition to the configuration above, in the touch panel of the present invention it is preferable
that the driver electrodes include a plurality of driver electrode parts interconnected by first bridge parts,
that the detection electrodes include a plurality of detection electrode parts interconnected by second bridge parts,
that the driver electrode parts, the first bridge parts, and the detection electrode parts be in the same layer, the second bridge parts being in a layer different from the driver electrode parts and the detection electrode parts, the complementary electrodes, at a portion thereof overlapping the detection electrodes, being in the same layer as the first bridge parts,
that the detection electrode parts be aligned along the column direction,
that the driver electrode parts be between detection electrode parts adjacent to each other in the row direction, and
that the complementary electrodes extend between driver electrodes adjacent to each other in the column direction.
According to this configuration, even if it is necessary to dispose the complementary electrodes in the same layer as the driver electrode parts and the detection electrode parts, it is possible to avoid having the complementary electrodes and the detection electrodes be adjacent to each other, and thus, it is possible to reduce the capacitance component indicated with Cfs in
In addition to the configuration above, in the touch panel of the present invention it is preferable
that the driver electrodes and the complementary electrodes be arranged in the same layer in an alternating fashion in the column direction,
that the detection electrodes be in a layer different from the driver electrodes and the complementary electrodes, and
that the detection electrodes be wider in the row direction at intersections thereof with the complementary electrodes, than at intersections thereof with the driver electrodes.
According to this configuration, it is not necessary to form a bridge part, thereby resulting in a relatively simple configuration.
Also, according to the configuration above, the capacitance component that is affected by the object to be detected among the capacitance between the driver electrodes and the detection electrodes is a portion of Cfs shown in
The present invention also includes a display device provided with the above-mentioned touch panel.
The present invention can be used for a display device of various types of electronic devices as a display device in which a liquid crystal panel having a display function is combined with a touch panel function.
Number | Date | Country | Kind |
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2011-089461 | Apr 2011 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP2012/059726 | 4/9/2012 | WO | 00 | 10/9/2013 |