Patent Application
20180173366
The present disclosure relates to the field of touch display technology, and more particularly to an apparatus and method for capacitance calibration, and a touch display device.
A projection capacitive touch display panel is provided with an X-axis electrode layer and a Y-axis electrode layer stacked on top of each other and insulated from each other.
When no conductive object is in contact with the touch display panel, coupling capacitors CM are formed between the touch electrode rows and the touch electrode columns (e.g., at their intersections), and the capacitance of the capacitor CM is referred to as the base capacitance. When a finger or other conductive object touches the touch display panel, the capacitance of the coupling capacitor CM will change. The touch position of the finger or other conductive object on the touch display panel can be determined by measuring the change in the capacitance of each coupling capacitor CM.
In the prior art, the capacitance of the coupling capacitor is measured only upon powering up of the touch display panel and the measurement result is set as the base capacitance of the coupling capacitor. The base capacitance is not updated thereafter. However, the base capacitance may change over time or depending on the picture displayed on the touch display panel. The change in the base capacitance may cause false recognition of touch operations, such as false positives.
Embodiments of the present disclosure provide an apparatus and method for capacitance calibration and a touch display device, which may alleviate, mitigate or eliminate at least one of the above-mentioned problems.
According to an aspect of the present disclosure, an apparatus is provided for calibrating a base capacitance of a touch display panel. The touch display panel is provided with a first electrode layer and a second electrode layer stacked on top of each other and insulated from each other. The first electrode layer comprises at least one row of touch electrodes. The second electrode layer comprises at least one column of touch electrodes. The at least one row of touch electrodes and the at least one column of touch electrodes form at least one coupling capacitor. The apparatus comprises a detection unit configured to measure a capacitance of the coupling capacitor in each of a plurality of non-touch time periods, and a calibration unit configured to calibrate the base capacitance of the coupling capacitor at each measurement based on the measured capacitance.
In some embodiments, the plurality of non-touch time periods are periodic.
In some embodiments, each of the plurality of non-touch time periods is inserted between a corresponding display time period and a corresponding touch time period that are allocated for the touch display panel.
In some embodiments, the plurality of non-touch time periods are aperiodic.
In some embodiments, the detection unit comprises a charge/discharge module configured to charge the touch electrodes until a voltage across the coupling capacitor reaches a target value, and then to discharge the coupling capacitor to detect an amount of charge stored in the coupling capacitor, and a capacitance calculation module configured to calculate the capacitance of the coupling capacitor based on the target value and the amount of charge.
In some embodiments, the apparatus further comprises a comparison unit configured to compare the measured capacitance with an original capacitance at each measurement. The calibration unit is further configured to set the base capacitance to the measured capacitance in response to the comparison unit indicating that an absolute value of a difference between the measured capacitance and the original capacitance is greater than a threshold.
According to another aspect of the present disclosure, a method is provided for calibrating a base capacitance of a touch display panel. The touch display panel is provided with a first electrode layer and a second electrode layer stacked on top of each other and insulated from each other. The first electrode layer comprises at least one row of touch electrodes. The second electrode layer comprises at least one column of touch electrodes. The at least one row of touch electrodes and the at least one column of touch electrodes form at least one coupling capacitor. The method comprises measuring a capacitance of the coupling capacitor in each of a plurality of non-touch time periods, and calibrating the base capacitance of the coupling capacitor at each measurement based on the measured capacitance.
In some embodiments, the plurality of non-touch time periods are periodic.
In some embodiments, each of the plurality of non-touch time periods is inserted between a corresponding display time period and a corresponding touch time period that are allocated for the touch display panel.
In some embodiments, the plurality of non-touch time periods are aperiodic.
In some embodiments, the step of measuring comprises charging the touch electrodes until a voltage across the coupling capacitor reaches a target value, discharging the coupling capacitor to detect an amount of charge stored in the coupling capacitor, and calculating the capacitance of the coupling capacitor based on the target value and the amount of charge.
In some embodiments, the step of calibrating comprises comparing the measured capacitance with an original capacitance, and setting the base capacitance to the measured capacitance in response to an absolute value of a difference between the measured capacitance and the original capacitance being greater than a threshold.
According to yet another aspect of the present disclosure, a touch display device is provided which comprises a touch display panel provided with a first electrode layer and a second electrode layer stacked on top of each other and insulated from each other, the first electrode layer comprising at least one row of touch electrodes, the second electrode layer comprising at least one column of touch electrodes, the at least one row of touch electrodes and the at least one column of touch electrodes forming at least one coupling capacitor, a detection unit configured to measure a capacitance of the coupling capacitor in each of a plurality of non-touch time periods, and a calibration unit configured to calibrate a base capacitance of the coupling capacitor at each measurement based on the measured capacitance.
These and other aspects of the present disclosure will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.
Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. Apparently, the embodiments described are merely illustrative and not restrictive. All other embodiments derived from the embodiments of the present disclosure by one of ordinary skill in the art without making any inventive effort fall within the scope of the present disclosure.
Referring to
In this way, the base capacitance is calibrated when the touch display panel is in use, so that erroneous recognition of touch operations due to a change in the base capacitance is reduced, thereby improving the accuracy of the touch operations.
The non-touch time period as described herein refers to a period of time that is not allocated to a touch display panel for detecting a touch operation. In other words, the non-touch time period does not overlap with a touch time period.
The plurality of non-touch time periods can be periodic. In some embodiments, each non-touch time period is inserted between a display time period and a touch time period that are allocated for the touch display panel. For example, the non-touch time period may be inserted after the display time period and before the touch time period. In this way, the base capacitance is updated before each touch time period, so that the accuracy of the recognition of the touch operation is improved. Other embodiments are possible. For example, the non-touch time period may overlap with the display time period. For another example, the detection and calibration of the base capacitance may be performed at a fixed interval without the need to be performed before each touch time period. Alternatively, the plurality of non-touch time periods may also be aperiodic.
Referring to
In this implementation, the detection of the amount of charge may be based on the formula Q=I×t, and the detection of the capacitance may be based on the formula C=Q/U, where Q is the amount of charge stored by the coupling capacitor, I is the current generated by discharging the coupling capacitor, t is the discharge time, U is the voltage across the coupling capacitor, and C is the capacitance of the coupling capacitor. The implementation of the capacitance detection unit 110 is however not so limited.
Referring to
In this implementation, the base capacitance is set to the measured capacitance only when the absolute value of the difference between the measured capacitance and the original capacitance is greater than the threshold. This can save the processing resources of the system.
Referring to
At step 210, the capacitance of the coupling capacitor is measured in each of a plurality of non-touch time periods.
At step 220, the base capacitance of the coupling capacitor is calibrated at each measurement based on the measured capacitance.
The measurement 210 of the capacitance of the coupling capacitor may specifically include the following steps.
At step 211, the touch electrodes are charged until a voltage across the coupling capacitor reaches a target value.
At step 212, the coupling capacitor is discharged to detect an amount of charge stored by the coupling capacitor.
At step 213, the capacitance of the coupling capacitor is calculated based on the target value and the amount of charge.
In addition, in some embodiments, the calibration 220 of the base capacitance may include comparing the measured capacitance with an original capacitance, and setting the base capacitance to the measured capacitance in response to an absolute value of a difference between the measured capacitance and the original capacitance being greater than a threshold.
The above method embodiments have the same advantages as the apparatus embodiments described with respect to
It will be appreciated that the various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The foregoing are specific embodiments of the present disclosure. Various modifications and variations can be made by one of ordinary skill in the art without departing from the spirit and essence of the disclosure, and such modifications and variations are intended to be encompassed within the scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201610371446.4 | May 2016 | CN | national |
The present application is the U.S. national phase entry of PCT/CN2017/073557, with an international filing date of Feb. 15, 2017, which claims the benefit of Chinese Patent Application No. 201610371446.4, filed on May 30, 2016, the entire disclosures of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2017/073557 | 2/15/2017 | WO | 00 |
