CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of the filing date of Chinese Patent Application No. 201810095179.1 filed on Jan. 31, 2018, the disclosure of which is hereby incorporated in its entirety by reference.

TECHNICAL FIELD

The present disclosure relates to display technology, and in particular, to a pressure detecting circuit, a pressure detecting method, a display panel, and a display apparatus.

BACKGROUND

An active piezoresistive detection circuit or a passive piezoresistive detection circuit is currently used to detect resistance of a piezoresistive sensor, that is, piezo-resistance.FIG. 1is a schematic diagram of a passive piezoresistive detection circuit in the related art. As shown inFIG. 1, the passive piezoresistive detection circuit is composed of a piezoresistive sensor PR′, a thin film transistor (TFT) SEL′, and a resistive voltage amplifier.

However, the piezoresistive detection circuits in the related art have the following shortcomings: first, the piezo-resistance is detected after being coupled to an amplifier in a normally open state. Therefore, current leakage often occurs. TakingFIG. 1as an example, the leaked current could have a value of NXVB′/RX′, where RX′ is a resistance of the piezoresistive sensor PR′, VB′ is a preset voltage, N is the number of columns of the piezoresistive sensor PR′ array. Furthermore, the on-state resistance of the thin film transistor TFT is so large that change of the current signal is too small, thereby leading to a large detection error. Second, the active piezoresistive detection circuit consumes a large amount of current.

BRIEF SUMMARY

One example of the present disclosure provides a pressure detecting circuit. The pressure detecting circuit may include a pressure sensing circuit; a signal generating circuit; and a frequency detecting circuit. The pressure sensing circuit and the signal generating circuit may be configured to constitute an oscillating circuit; the signal generating circuit may be configured to generate an oscillating signal based on a pressure sensed by the pressure sensing circuit; and the frequency detecting circuit may be configured to detect a frequency of the oscillating signal and determine a value of the pressure sensed by the pressure sensing circuit based on the frequency of the oscillating signal.

Optionally, the signal generating circuit comprises comparing circuit, a first input terminal of the comparing circuit being coupled to a first terminal of the pressure sensing circuit, and an output terminal of the comparing circuit being coupled to a second terminal of the pressure sensing circuit; and a feedback circuit, a first terminal of the feedback circuit being coupled to a second input terminal of the comparison circuit, and a second terminal of the feedback circuit being coupled to the output terminal of the comparing circuit. The comparing circuit is configured to generate the oscillating signal by comparing a voltage of the first terminal of the pressure sensing circuit with a voltage of the first terminal of the feedback circuit, and outputs the oscillating signal through the output terminal of the comparing circuit.

Optionally, the pressure sensing circuit comprises M pressure sensing subcircuits, each of the M pressure sensing subcircuits comprising a pressure sensitive component, a first transistor, and a first capacitor, where M is a positive integer. A first terminal of each of the M pressure sensing subcircuits is coupled to the first input terminal of the comparing circuit, a second terminal of each of the M pressure sensing subcircuits is coupled to the output terminal of the comparing circuit, and each of the M pressure sensing circuits is configured to participate in oscillation of the oscillating circuit when the corresponding first transistor is turned on.

Optionally, the pressure detecting circuit comprises M scanning signal lines, and a gate of the first transistor of each of the M pressure sensing subcircuits is respectively coupled to one of the M scanning signal lines, and each of the scanning signal lines is configured to control whether a pressure sensing subcircuit participates in oscillation or not by controlling opening or closing of the first transistor of the pressure sensing subcircuit.

Optionally, one terminal of the first capacitor is grounded, the other terminal of the first capacitor is coupled to one terminal of the pressure sensitive component, a first node is between the first capacitor and the pressure sensitive component, the other terminal of the pressure sensitive component is coupled to the output terminal of the comparing circuit, the first terminal of the first transistor is coupled to the first node, and the second terminal of the first transistor is coupled to the first input terminal of the comparing circuit.

Optionally, the feedback circuit comprises a first resistor and a second resistor, and one terminal of the first resistor is coupled to the output terminal of the comparing circuit, the other terminal of the first resistor is coupled to one terminal of the second resistor, a second node is disposed between the first resistor and the second resistor and coupled to the second input terminal of the comparing circuit, and the other terminal of the second resistor is grounded.

Optionally, the signal generating circuit further comprises a voltage stabilizing diode, one terminal of the voltage stabilizing diode is coupled to the output terminal of the comparing circuit and the other terminal of the voltage stabilizing diode is grounded.

Optionally, the comparing circuit is a comparator or an operational amplifier.

Optionally, the frequency detecting circuit comprises a shaper, a monostable flip-flop, an RS flip-flop, a counter, and a latch. The shaper is configured to shape the oscillating signal to generate and output a shaped oscillating signal. The monostable flip-flop is configured to convert the shaped oscillating signal to a pulse signal. The RS flip-flop is configured to generate a trigger signal based on the pulse signal. The counter is configured to count under control of the trigger signal to record a number of count pulses between two adjacent pulse signals. The latch is configured to latch the number of count pulses between the two adjacent pulse signals.

Optionally, the oscillating signal is a square wave signal.

Optionally, the M pressure sensing subcircuits are in a same column.

Optionally, the pressure sensitive component is a varistor.

One example of the present disclosure is a display panel. The display panel may include N pressure detecting circuits according to one embodiment of the present disclosure. N is a positive integer.

Optionally, the display panel comprises a pressure sensing array comprising M rows and N columns of the pressure sensing subcircuits of the N pressure detecting circuits, wherein gates of first transistors of N pressure sensing subcircuits in a same row are coupled to a same scanning signal line, and the first transistors in the M rows of the pressure sensing subcircuits are turned on row by row.

Optionally, the display panel further comprises a pixel array comprising M rows and N columns of pixel units, wherein the M rows and N columns of pixel units are respectively disposed corresponding to the M rows and N columns of the pressure sensing subcircuits, and each of pressure sensing subcircuits is arranged in an interval between two of the pixel units.

One example of the present disclosure is a display apparatus comprising the display panel according to one embodiment of the present disclosure.

One example of the present disclosure is a pressure detecting method. The pressure detecting method comprise constructing an oscillating circuit comprising a signal generating circuit and a pressure sensing circuit, wherein the signal generating circuit is configured to generate an oscillating signal based on a pressure sensed by the pressure sensing circuit; detecting a frequency of the oscillating signal; and determining a valued of the pressure sensed by the pressure sensing circuit based on the frequency of the oscillating signal.

