Display device and its control method

Abstract

A display device and a control method thereof, the display device comprising a display panel, a noise detection circuit and a processing circuit. The noise detection circuit is used to detect and process a voltage signal of a common electrode of the display panel to output a free-running signal and a noise synchronization signal. The processing circuit is used to receive the free-running signal and the noise synchronization signal. When the free-running signal has a first level, the processing circuit instantly receives a touch signal output by the display panel. When the free-running signal has a second level, the processing circuit receives the touch signal output by the display panel according to the noise synchronization signal. The display device of the present disclosure detects noise through the noise detection circuit to generate a free-running signal and a noise synchronization signal accordingly. When noise is detected, the processing circuit in the display device can selectively perform touch sensing and filtering operations according to the levels of the free-running signal and the noise synchronization signal.

Description

Technical Field

[0001] The present disclosure relates to a display device and a control method thereof, and more particularly to a display device having a noise detection circuit and a control method thereof. Background Art

[0002] An electrophoretic display (EPD) often makes mistakes due to excessive noise generated during a display process (e.g., a page turning process) according to coordinates generated by an active capacitive stylus or an electromagnetic resonance (EMR) stylus, such as incorrect display position or delayed display.

[0003] The current solution is to filter all signals generated during the display process. However, during the filtering process, the display cannot perform coordinate detection operations or needs to perform complex calculations to obtain coordinates, resulting in a delay in coordinate generation. Summary of the Invention

[0004] One aspect of the present disclosure is a display device. The display device includes a display panel, a noise detection circuit, and a processing circuit. The display panel includes a common electrode, wherein the display panel has a touch function and detects a contact position of an object to output a touch signal. The noise detection circuit is configured to detect and process a voltage signal of the common electrode to output a free-running signal and a noise synchronization signal. The processing circuit is coupled to the display panel and the noise detection circuit and is configured to receive the free-running signal and the noise synchronization signal. When the free-running signal has a first level, the processing circuit immediately receives the touch signal output by the display panel and converts the touch signal into a position signal. When the free-running signal has a second level different from the first level, the processing circuit receives the touch signal output by the display panel according to the noise synchronization signal and converts the touch signal into the position signal.

[0005] In another embodiment, the processing circuit includes a first filter circuit. When the free-running signal has the second level, the processing circuit filters the position signal through the first filter circuit.

[0006] In another embodiment, the noise detection circuit includes an amplifier circuit, an analog-to-digital converter, a clipping circuit, a second filter circuit, and a comparison circuit. The amplifier circuit is used to amplify the voltage signal of the common electrode to generate an amplified voltage signal. The analog-to-digital converter is coupled to the amplifier circuit and is used to perform an analog-to-digital conversion operation on the amplified voltage signal to generate a digital voltage signal. The clipping circuit is coupled to the analog-to-digital converter and is used to generate a first digital voltage signal and a second digital voltage signal according to a reference value and the digital voltage signal. The second filter circuit is coupled to the clipping circuit and is used to generate a noise level signal according to the first digital voltage signal and the second digital voltage signal. The comparison circuit is coupled to the second filter circuit and is used to compare the noise level signal with a threshold value. Wherein, when the noise level signal is not greater than the threshold value, the comparison circuit outputs the free-running signal with the first level, and when the noise level signal is greater than the threshold value, the comparison circuit outputs the free-running signal with the second level.

[0007] In another embodiment, within the time of one frame, the second filter circuit outputs eight of the noise level signals.

[0008] In another embodiment, when the noise synchronization signal has a third level, the processing circuit does not receive the touch signal output by the display panel. When the noise synchronization signal has a fourth level different from the third level, the processing circuit receives the touch signal output by the display panel and converts the touch signal into the position signal.

[0009] One aspect of the present disclosure is a control method. The control method is applicable to a display device and includes: detecting a contact position of an object through a display panel with touch function to output a touch signal; and detecting and processing a voltage signal of a common electrode of the display panel through a noise detection circuit to output a free-running signal and a noise synchronization signal. Wherein, when the free-running signal has a first level, the processing circuit immediately receives the touch signal output by the display panel and converts the touch signal into a position signal. When the free-running signal has a second level different from the first level, the processing circuit receives the touch signal output by the display panel according to the noise synchronization signal and converts the touch signal into the position signal.

[0010] In another embodiment, when the free-running signal has the second level, the position signal is filtered by a first filter circuit in the processing circuit.

[0011] In another embodiment, the operations of detecting and processing a voltage signal of a common electrode of the display panel by a noise detection circuit to output a free-running signal and a noise synchronization signal include: amplifying the voltage signal of the common electrode by an amplifying circuit to generate an amplified voltage signal; performing an analog-to-digital conversion operation on the amplified voltage signal by an analog-to-digital converter to generate a digital voltage signal; generating a first digital voltage signal and a second digital voltage signal by a clipping circuit according to a reference value and the digital voltage signal; generating a noise level signal by a second filtering circuit according to the first digital voltage signal and the second digital voltage signal; and comparing the noise level signal with a threshold by a comparison circuit, wherein when the noise level signal is not greater than the threshold, the free-running signal with the first level is output by the comparison circuit, and when the noise level signal is greater than the threshold, the free-running signal with the second level is output by the comparison circuit.

[0012] In another embodiment, eight noise level signals are output within the time of one frame.

[0013] In another embodiment, when the noise synchronization signal has a third level, the touch signal output by the display panel is not received. When the noise synchronization signal has a fourth level different from the third level, the touch signal output by the display panel is received, and the touch signal is converted into a position signal.

[0014] In summary, the display device of the present disclosure detects noise through a noise detection circuit to correspondingly generate a free-running signal and a noise synchronization signal. When noise is detected, the processing circuit in the display device can selectively perform touch sensing and filtering operations according to the levels of the free-running signal and the noise synchronization signal. In this way, the problems of complex calculations and coordinate generation delays are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. is a schematic diagram of a display device according to some embodiments of the present disclosure;

[0016] Figure 2 FIG. is a schematic diagram of a noise detection circuit of a display device according to some embodiments of the present disclosure;

[0017] Figure 3 FIG. is a schematic diagram of an amplifying circuit of a noise detection circuit according to some embodiments of the present disclosure;

[0018] Figure 4 FIG. is a flowchart of a control method of a display device according to some embodiments of the present disclosure;

[0019] Figure 5 is a flowchart showing one operation of a control method according to some embodiments of the present disclosure;

[0020] Figure 6 is a timing diagram showing a noise level signal, a free-running signal, and a noise synchronization signal according to some embodiments of the present disclosure.

[0021]

Symbol Description

[0022] 10: Object

[0023] 100: Display device

[0024] 110: Display panel

[0025] 111: Common electrode

[0026] 120: Noise detection circuit

[0027] 121: Amplification circuit

[0028] 123: Analog-to-digital converter

[0029] 125: Carrier cut-off circuit

[0030] 127, 131: Filter circuit

[0031] 129: Comparison circuit

[0032] 130: Processing circuit

[0033] 200: Control method

[0034] VCOM: Voltage signal

[0035] VA: Amplified voltage signal

[0036] D(n): Digital voltage signal

[0037] D + (n): First digital voltage signal

[0038] D - (n): Second digital voltage signal

[0039] NL[m]: Noise level signal

[0040] Thr: Threshold

[0041] NNS: Noise synchronization signal

[0042] FR: Free-running signal

[0043] TS: Touch signal

[0044] PS: Position signal

[0045] R1, R2, Ra: Resistors

[0046] Ca: Capacitor

[0047] LPF: Low - Pass Filter Circuit

[0048] OP: Operational Amplifier

[0049] Vref: Reference Voltage

[0050] VSS: System Low Voltage

[0051] S201~S204: Operations

[0052] S221~S225: Sub - operations

[0053] P1: First Period

[0054] P2 Second Period

[0055] P1a, P1b: Sub - periods Detailed Embodiment

[0056] The following is a detailed description with reference to the accompanying drawings through examples. However, the specific examples described are only used to explain the present case and not to limit the present case. The description of the structure and operation is not used to limit the execution order. Any structure formed by recombining elements and producing a device with equivalent functions is within the scope covered by the present disclosure.

[0057] The terms used throughout the specification and claims, unless otherwise specifically noted, generally have their ordinary meanings as used in this field, in the context of this disclosure, and in the context of the particular content.

[0058] Regarding the use of "coupled" or "connected" in this article, it can refer to two or more elements making direct physical or electrical contact with each other, or making indirect physical or electrical contact with each other. It can also refer to two or more elements operating or acting on each other.

[0059] Please refer to Figure 1 , a display device 100 illustrated according to an embodiment of the present disclosure includes a display panel 110, a noise detection circuit 120, and a processing circuit 130. Among them, the display device 100 can be an electrophoretic display (EPD). However, the present disclosure is not limited thereto. When an object 10 (such as a finger, an active capacitive stylus, an electromagnetic (EMR) stylus, etc.) operates on the display panel 110 of the display device 100, the processing circuit 130 controls the display panel 110 to display a corresponding indicating object (such as a cursor, handwriting, etc.).

[0060] In some embodiments, the display panel 110 detects the contact position of the object 10 to output a touch signal TS to the processing circuit 130. The processing circuit 130 receives the touch signal TS for calculation to convert the touch signal TS into a position signal PS. For example, the position signal PS includes coordinate information on a reference coordinate system (not shown in the figure), and the reference coordinate system can be the screen coordinate system of the display panel 110. The display panel 110 receives the position signal PS generated by the processing circuit 130 to display an indication object at the coordinates corresponding to the contact position of the object 10.

[0061] Specifically, the display panel 110 may include a common electrode 111 and a display electrode (not shown in the figure). A plurality of microcapsules (not shown in the figure) are formed between the common electrode 111 and the display electrode, and each microcapsule includes a plurality of positively charged particles and a plurality of negatively charged particles. In some embodiments, the display panel 110 can provide a voltage difference between the common electrode 111 and the display electrode through a driving circuit (not shown in the figure) to control the movement of the positively charged particles and the negatively charged particles. The driving circuit can provide different voltage differences for different positions on the display panel 110 according to the position signal PS generated by the processing circuit 130 to display an indication object (e.g., an image).

[0062] However, the position signal PS is easily affected by noise during the display process, so that the display panel 110 may display the indication object at an incorrect position or may delay the display of the indication object. It should be noted that the noise detection circuit 120 is coupled to the display panel 110 and receives a voltage signal VCOM of the common electrode 110 to detect noise. The processing circuit 130 is coupled to the noise detection circuit 120 and the display panel 110 and operates according to the detection result of the noise detection circuit 120. In this way, the problems of the above display device 100 are solved.

[0063] Please refer to Figure 2 In some embodiments, the noise detection circuit 120 includes an amplification circuit 121, an analog-to-digital converter 123, a clipping circuit 125, a filtering circuit 127, and a comparison circuit 129. The amplification circuit 121 is used to receive and amplify the voltage signal VCOM of the common electrode 111 to generate an amplified voltage signal VA.

[0064] Please also refer to Figure 3, specifically, the amplifier circuit 121 includes a resistor R1, a resistor R2, an operational amplifier OP, and a low-pass filter circuit LPF. The resistor R1 is coupled between the input terminal of the amplifier circuit 121 and the negative input terminal of the operational amplifier OP. The resistor R2 is coupled between the negative input terminal of the operational amplifier OP and the output terminal of the operational amplifier OP. The positive input terminal of the operational amplifier OP receives a reference voltage Vref. In some embodiments, the amplified voltage signal VA can be represented by the following equation (1):

[0065] Wherein, the resistance value of the resistor R1 can be 10 kΩ, the resistance value of the resistor R2 can be 10 kΩ, the reference voltage Vref can be 0 V, and the voltage signal VCOM can be a DC voltage of -1.5 V. Note that the voltage signal VCOM may vary (e.g., ±1 V) due to noise interference.

[0066] As Figure 3 shown, the low-pass filter circuit LPF includes a resistor Ra and a capacitor Ca, and is used to reduce the distortion of the amplified voltage signal VA. The resistor Ra is coupled between the output terminal of the operational amplifier OP and the output terminal of the amplifier circuit 121. One end of the capacitor Ca is coupled between the resistor Ra and the output terminal of the amplifier circuit 121, and the other end of the capacitor Ca receives a system low voltage VSS. Specifically, the resistance value of the resistor Ra can be 4.7 kΩ, and the capacitance value of the capacitor Ca can be 100 pF.

[0067] As Figure 2 shown, the analog-to-digital converter 123 is coupled to the amplifier circuit 121, and is used to perform an analog-to-digital conversion operation on the amplified voltage signal VA to generate a digital voltage signal D(n). The clipping circuit 125 is coupled to the analog-to-digital converter 123, and is used to generate a first digital voltage signal D + (n) and a second digital voltage signal D - (n) according to a reference value (not shown in the figure) and the digital voltage signal D(n). In some embodiments, the first digital voltage signal D + (n) and the second digital voltage signal D - (n) can be represented by the following equations (2) and (3) respectively:

[0068] D + (n) = D(n) - Dref...(2);

[0069] D - (n) = Dref - D(n)...(3), where Dref is the reference value, and the sampling points of n can be 8, 16, 32, or 64. In some embodiments, Dref can be expressed as: Dref = VA / 2^m, where m can be 10.

[0070] The filter circuit 127 is coupled to the carrier cut-off circuit 125 and is configured to generate a noise level signal NL[m] according to the first digital voltage signal D + (n) and the second digital voltage signal D - (n). In some embodiments, the filter circuit 127 may be an average filter. In some embodiments, the noise level signal NL[m] can be represented by the following equation (4):

[0071] where o can be 8, 16, or 32.

[0072] The comparison circuit 129 is coupled to the filter circuit 127 and the processing circuit 130, and is configured to compare the noise level signal NL[m] with a threshold Thr (e.g., 800 - 1000), and output a free-running signal FR with a high level or a low level to the processing circuit 130 according to the comparison result of the noise level signal NL[m] and the threshold Thr. In some embodiments, the noise detection circuit 120 can selectively output a noise synchronization signal NNS to the processing circuit 130 according to the voltage level of the free-running signal FR through the comparison circuit 129.

[0073] For another example Figure 1 As shown, the processing circuit 130 is coupled to the display panel 110 and the noise detection circuit 120, and is configured to receive the free-running signal FR and the noise synchronization signal NNS generated by the noise detection circuit 120 to perform related operations on the display panel 110.

[0074] In some embodiments, the processing circuit 130 includes a filter circuit 131, where the filter circuit 131 may be a median filter. When the noise detection circuit 120 detects noise, the processing circuit 130 can filter the position signal PS calculated by the processing circuit 130 through the filter circuit 131 to remove the influence of the noise.

[0075] Please refer to Figure 4 , Figure 4 A control method 200 illustrated according to one embodiment of the present disclosure is described. As Figure 1 shown, the display device 100 can execute the control method 200 to perform related operations. In some embodiments, the control method 200 includes operations S201 - S205.

[0076] In operation S201, the display device 100 detects the contact position of the object 10 through the display panel 110 to output a touch signal TS. In operation S202, the display device 100 detects and processes the voltage signal VCOM of the common electrode 111 of the display panel 110 through the noise detection circuit 120 to output a free-running signal FR and a noise synchronization signal NNS.

[0077] Please refer to Figure 5 , in some embodiments, operation S202 includes sub-operations S221 to S225. In sub-operation S221, the display device 100 amplifies the voltage signal VCOM of the common electrode 111 through the amplifier circuit 121 to generate an amplified voltage signal VA. In sub-operation S222, the display device 100 performs an analog-to-digital conversion operation on the amplified voltage signal VA through the analog-to-digital converter 123 to generate a digital voltage signal D(n). In sub-operation S223, the display device 100 generates a first digital voltage signal D + (n) and a second digital voltage signal D - (n) according to the reference value and the digital voltage signal D(n) through the clipping circuit 125. In sub-operation S224, the display device 100 generates a noise level signal NL[m] according to the first digital voltage signal D + (n) and the second digital voltage signal D - (n) through the filter circuit 127. In sub-operation S225, the display device 100 compares the noise level signal NL[m] with the threshold Thr through the comparison circuit 129 and outputs a free-running signal FR with a high level or a low level according to the comparison result between the noise level signal NL[m] and the threshold Thr.

[0078] Next, as Figure 4 shown, in operation S203, the display device 100 receives the free-running signal FR through the processing circuit 130 and judges the voltage level of the free-running signal FR to determine whether to execute operation S204 or operation S205.

[0079] In some embodiments, the voltage signal VCOM is not affected by noise, so that the noise level signal NL[m] output by the second filter circuit 127 is not greater than the threshold Thr. Accordingly, the comparison circuit 129 outputs a free-running signal FR with a high level. As Figure 4 shown, in operation S204, when the free-running signal FR has a high level, the display device 100 immediately receives the touch signal TS output by the display panel 110 through the processing circuit 130 and converts the touch signal TS into a position signal PS.

[0080] In other partial embodiments, the voltage signal VCOM is affected by noise, such that the noise level signal NL[m] output by the second filter circuit 127 is greater than the threshold Thr. Accordingly, the comparison circuit 129 outputs a free-running signal FR with a low level. As Figure 4 shown, in operation S205, when the free-running signal FR has a low level, the display device 100 receives the touch signal TS output by the display panel 110 according to the noise synchronization signal NNS through the processing circuit 130, and converts the touch signal TS into a position signal PS. In addition, when the free-running signal FR has a low level, the display device 100 can also filter the position signal PS through the filter circuit 131 in the processing circuit 130.

[0081] Please refer to Figure 6 , Figure 6 for a timing diagram describing the noise level signal NL[m], the free-running signal FR, and the noise synchronization signal NNS. As Figure 6 shown, the time of one frame (e.g., the first frame (1st frame) or the second frame (2nd frame)), such as 1 / 75 second, includes a first period P1 and a second period P2. In the first period P1 of the first frame, the display device 100 performs an operation of noise detection through the noise detection circuit 120. In some embodiments, within the time of one frame, the filter circuit 127 outputs eight noise level signals NL[1] to NL[8]. In this way, at least one noise detection can be performed before the object 10 (e.g., a stylus) outputs a signal each time.

[0082] For example, in a sub-period P1a of the first period P1 of the first frame, the voltage signal VCOM is not affected by noise. Therefore, the noise level signals NL[1] to NL[2] output by the filter circuit 127 are not greater than the threshold Thr, such that the free-running signal FR maintains a high level. When the free-running signal FR has a high level, the processing circuit 130 can perform the touch sensing operation at any time (i.e., the operation of calculating the position signal PS described above).

[0083] In a sub-period P1b of the first period P1 of the first frame, the voltage signal VCOM is affected by noise. Therefore, the noise level signals NL[3] to NL[8] output by the filter circuit 127 are greater than the threshold Thr, such that the free-running signal FR switches to a low level. When the free-running signal FR has a low level, the processing circuit 130 is restricted to perform the touch sensing operation only when the noise synchronization signal NNS has a low level, and also performs a filtering operation through the filter circuit 131 (i.e., the operation of filtering the position signal PS described above).

[0084] During the second period P2 of the first frame, the display device 100 ends the operation of noise detection. Further, the display device 100 performs touch sensing and filtering operations according to the low-level noise synchronization signal NNS through the processing circuit 130 to make up for the touch sensing operations that were not performed due to noise interference previously.

[0085] In some embodiments, the calculation of the foregoing reference value Dref can be performed during the second period P2. For example, during the second period P2, the processing circuit 130 can average the eight digital voltage signals D(n) generated during the first period P1 to calculate the reference value Dref, and thus provide it to the chopping circuit 125.

[0086] In other partial embodiments, during the first period P1 of the second frame, the free-running signal FR remains at a low level, indicating that the display device 100 is still affected by noise. Therefore, the processing circuit 130 is still restricted. At the end of the first period P1 of the second frame, due to the disappearance of noise interference, the free-running signal FR switches from a low level to a high level. During the second period P2 of the second frame, the processing circuit 130 can arbitrarily perform touch sensing operations according to the high-level free-running signal FR.

[0087] In summary, the display device 100 of the present disclosure detects noise through the noise detection circuit 120 to correspondingly generate a free-running signal FR and a noise synchronization signal NNS. When noise is detected, the processing circuit 130 in the display device 100 can selectively perform touch sensing and filtering operations according to the levels of the free-running signal FR and the noise synchronization signal NNS. In this way, the problems of complex calculations and coordinate generation delays are solved.

[0088] Although the present disclosure has been disclosed as above in embodiments, it is not intended to limit the present disclosure. Those of ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the scope defined by the appended claims.

Claims

1. A display device, characterized in that, it comprises: a display panel including a common electrode, wherein the display panel has a touch function and detects a contact position of an object to output a touch signal; a noise detection circuit for detecting and processing a voltage signal of the common electrode to output a free-running signal and a noise synchronization signal; and a processing circuit coupled to the display panel and the noise detection circuit and for receiving the free-running signal and the noise synchronization signal, the processing circuit including a first filter circuit, wherein, when the free-running signal has a first level, the processing circuit immediately receives the touch signal output by the display panel and converts the touch signal into a position signal, when the free-running signal has a second level lower than the first level, the processing circuit receives the touch signal output by the display panel according to the noise synchronization signal and converts the touch signal into the position signal, and the processing circuit filters the position signal through the first filter circuit.

2. The display device according to claim 1, characterized in that, the noise detection circuit includes: an amplification circuit for amplifying the voltage signal of the common electrode to generate an amplified voltage signal; an analog-to-digital converter coupled to the amplification circuit and for performing an analog-to-digital conversion operation on the amplified voltage signal to generate a digital voltage signal; a clipping circuit coupled to the analog-to-digital converter and for generating a first digital voltage signal and a second digital voltage signal according to a reference value and the digital voltage signal; a second filter circuit coupled to the clipping circuit and for generating a noise level signal according to the first digital voltage signal and the second digital voltage signal; and a comparison circuit coupled to the second filter circuit and for comparing the noise level signal with a threshold value, wherein, when the noise level signal is not greater than the threshold value, the comparison circuit outputs the free-running signal having the first level, when the noise level signal is greater than the threshold value, the comparison circuit outputs the free-running signal having the second level.

3. The display device according to claim 2, characterized in that, in the time of one frame, the second filter circuit outputs eight noise level signals.

4. The display device according to claim 1, characterized in that, when the noise synchronization signal has a third level, the processing circuit does not receive the touch signal output by the display panel, when the noise synchronization signal has a fourth level different from the third level, the processing circuit receives the touch signal output by the display panel and converts the touch signal into the position signal.

5. A control method applicable to a display device, characterized in that, it comprises: detecting a contact position of an object through a display panel having a touch function to output a touch signal; and detecting and processing a voltage signal of a common electrode of the display panel through a noise detection circuit to output a free-running signal and a noise synchronization signal, wherein, When the free-running signal has a first level, the touch signal output by the display panel is immediately received by a processing circuit, and the touch signal is converted into a position signal. When the free-running signal has a second level lower than the first level, the touch signal output by the display panel is received by the processing circuit according to the noise synchronization signal, and the touch signal is converted into the position signal, and the position signal is filtered by a first filtering circuit in the processing circuit.

6. The control method according to claim 5, wherein, The operations of detecting and processing a voltage signal of a common electrode of the display panel by a noise detection circuit to output a free-running signal and a noise synchronization signal include: amplifying the voltage signal of the common electrode by an amplifying circuit to generate an amplified voltage signal; performing an analog-to-digital conversion operation on the amplified voltage signal by an analog-to-digital converter to generate a digital voltage signal; generating a first digital voltage signal and a second digital voltage signal by a clipping circuit according to a reference value and the digital voltage signal; generating a noise level signal by a second filtering circuit according to the first digital voltage signal and the second digital voltage signal; and comparing the noise level signal with a threshold by a comparison circuit, wherein, when the noise level signal is not greater than the threshold, the free-running signal with the first level is output by the comparison circuit, when the noise level signal is greater than the threshold, the free-running signal with the second level is output by the comparison circuit.

7. The control method according to claim 6, wherein, Eight noise level signals are output within one frame time.

8. The control method according to claim 5, wherein, when the noise synchronization signal has a third level, the touch signal output by the display panel is not received, when the noise synchronization signal has a fourth level different from the third level, the touch signal output by the display panel is received, and the touch signal is converted into the position signal.

Images