Patent Publication Number: US-10789883-B2

Title: Sensing apparatus for display panel and operation method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of U.S. provisional application Ser. No. 62/580,996, filed on Nov. 2, 2017. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
    
    
     BACKGROUND 
     Field of the Invention 
     The invention relates to a display apparatus and more particularly, to a sensing apparatus for a display panel and an operating method thereof. 
     Description of Related Art 
     In a pixel circuit of a light emitting diode (LED) display panel such as an organic light emitting diode (OLED) display panel, the performance of the OLED declines along with the time of use. In order to compensate the performance decline of the OLED, a driving circuit senses the OLED through a sensing line of the display panel and converts a sensing result of the sensing line into sensing data to provide to an image processing circuit. The image processing circuit may generate compensated pixel data according to the sensing data. The driving circuit may drive the pixel circuit through data lines (i.e., source lines) of the display panel according to the compensated pixel data. Thereby, the performance decline of the OLED can be compensated. 
     The sensing result of the sensing line can be an analog signal, while the sensing data provided to the image processing circuit can be a digital signal. That is, the driving circuit can convert the sensing result of the sensing line into the sensing data with the use of an analog-to-digital converter (ADC). In anyway, a quantization and/or non-linear error between the sensing result and the sensing data may be generated by the ADC. Such error would cause the compensated image to have abnormal lines displayed by the display panel, which may be observed by a user. 
     SUMMARY 
     The invention provides a sensing apparatus and an operating method thereof for mitigating image abnormality resulting from quantization/non-linear error. 
     According to an embodiment of the invention, a sensing apparatus applicable to a driving circuit for driving a display panel is provided. The sensing apparatus includes a sensing circuit, an analog-to-digital converter (ADC) circuit, a disturbing circuit and an output circuit. The sensing circuit is configured to output a sensing signal indicating a sensing result of a sensing line of the display panel. The analog-to-digital converter circuit is coupled to the sensing circuit to receive the sensing signal and outputs sensing data related to the sensing signal. The disturbing circuit is coupled to the ADC circuit to receive the sensing data and generates a time-variant disturbance component to disturb the sensing data to generate disturbed data. The output circuit is coupled to the disturbing circuit to receive the disturbed data. 
     According to an embodiment of the invention, an operation method of a sensing apparatus is provided. The operation method includes: outputting, by a sensing circuit, a sensing signal indicating a sensing result of a sensing line of the display panel; outputting, by an analog-to-digital converter circuit, sensing data related to the sensing signal; generating, by a disturbing circuit, a time-variant disturbance component to disturb the sensing data to generate disturbed data; and receiving, by an output circuit, the disturbed data. 
     To sum up, in the sensing apparatus and the operating method of the embodiments of the invention, the disturbing circuit generates the time-variant disturbance component. The time-variant disturbance component is employed to disturb the sensing data output by the analog-to-digital converter circuit, so as to generate the disturbed data. In this way, the sensing apparatus can achieve mitigating image abnormality resulting from quantization/non-linear error. 
     To make the above features and advantages of the invention more comprehensible, embodiments accompanied with drawings are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a schematic circuit block diagram illustrating a sensing apparatus according to an embodiment of the invention. 
         FIG. 2  is a schematic circuit diagram illustrating a pixel circuit of a display panel according to an embodiment of the invention. 
         FIG. 3  is a flowchart illustrating an operation method of a sensing apparatus according to an embodiment of the invention. 
         FIG. 4  is a schematic waveform diagram illustrating output signals of an analog-to-digital converter (ADC) circuit and a disturbance circuit according to an embodiment of the invention. 
         FIG. 5  is a schematic circuit block diagram illustrating a sensing apparatus according to an embodiment of the invention. 
         FIG. 6  is a schematic circuit block diagram illustrating a sensing apparatus according to another embodiment of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The term “couple (or connect)” herein (including the claims) are used broadly and encompass direct and indirect connection or coupling means. For example, if the disclosure describes a first apparatus being coupled (or connected) to a second apparatus, then it should be interpreted that the first apparatus can be directly connected to the second apparatus, or the first apparatus can be indirectly connected to the second apparatus through other devices or by a certain coupling means. Moreover, elements/components/steps with same reference numerals represent same or similar parts in the drawings and embodiments. Elements/components/notations with the same reference numerals in different embodiments may be referenced to the related description. 
       FIG. 1  is a schematic circuit block diagram illustrating a sensing apparatus  100  according to an embodiment of the invention. A display apparatus  10  illustrated in  FIG. 1  includes a display panel  11 , a driving circuit  12  and an image processing circuit  13 . Based on a design requirement, the display panel  11  may be a light emitting diode (LED) display panel such as an organic light emitting diode (OLED) display panel or other display panels. The OLED display panel may have any available configuration known in the art and thus, will not be described for brevity. The display panel  11  has a plurality of data lines (e.g., a data line Ld illustrated in  FIG. 1 ) and a plurality of sensing lines (e.g., a sensing line Ls illustrated in  FIG. 1 ). The data line is also referred to as a source line. 
     The display panel  11  further has a pixel array, and the pixel array includes a plurality of pixel circuits. For example,  FIG. 2  is a schematic circuit diagram illustrating a pixel circuit PC of the display panel depicted in  FIG. 1  according to an embodiment of the invention. It is noted that the circuit illustrated in  FIG. 2  is explained with application to  FIG. 1  but is not limited to being applied to the configuration shown in  FIG. 1 . In the embodiment illustrated in  FIG. 2 , the display panel  11  includes the pixel circuit PC. The pixel circuit PC is coupled to a corresponding data line (e.g., the data line Ld illustrated in  FIG. 1 ) and a corresponding sensing line (e.g., the sensing line Ls illustrated in  FIG. 1 ) of the display panel  11 . The pixel circuit PC illustrated in  FIG. 2  may have any available conventional configuration known in the art and thus will not be described for brevity. In other embodiments, the implementation manner of the pixel circuit of the display panel  11  illustrated in  FIG. 1  is not limited to that of the pixel circuit PC illustrated in  FIG. 2 . 
     Referring to  FIG. 1 , the driving circuit  12  includes a receiving circuit Rx, a channel circuit CH and the sensing apparatus  100 . The receiving circuit Rx receives a pixel data string (i.e., compensated pixel data) from the image processing circuit  13  and provides the pixel data string to a plurality of channel circuits (e.g., the channel circuit CH illustrated in  FIG. 1 ). The channel circuit CH converts the pixel data into an analog driving voltage and outputs the driving voltage to the corresponding data line (e.g., the data line Ld illustrated in  FIG. 1 ) of the display panel  11 . The channel circuit CH, the receiving circuit Rx and the image processing circuit  13  may have any available configurations known in the art and thus, will not be described for brevity. 
     In the embodiment illustrated in  FIG. 1 , the sensing apparatus  100  includes a sensing circuit  110 , an analog-to-digital converter (ADC) circuit  120 , a disturbing (or scrambling) circuit  130  and an output circuit  140 . The sensing circuit  100  may sense (or sample) information related to a corresponding pixel circuit in the display panel  11  through the corresponding sensing line (e.g., the sensing line Ls illustrated in  FIG. 1 ) of the display panel  11 . The sensing circuit  110  may output a sense signal to the ADC circuit  120 . The sensing signal indicates a sensing result of the sensing line Ls of the display panel  11 . 
       FIG. 3  is a flowchart illustrating an operation method of a sensing apparatus according to an embodiment of the invention. It is noted that the flowchart illustrated in  FIG. 3  is explained with application to  FIG. 1  but is not limited to being applied to the configuration shown in  FIG. 1 . Referring to  FIG. 1  and  FIG. 3 , in step S 310 , the sensing circuit  110  outputs a sensing signal indicating a sensing result the sensing line Ls of the display panel  11 . The ADC circuit  120  is coupled to the sensing circuit  110  to receive the sensing signal. In step S 320 , the ADC circuit  120  outputs sensing data related to the sensing signal to the disturbing circuit  130 . The disturbing circuit  130  is coupled to the ADC circuit  120  to receive the sensing data. In step S 330 , the disturbing circuit  130  generates a time-variant disturbance component to disturb (or scramble) the sensing data to generate disturbed data. The driving circuit  140  is coupled to the disturbing circuit  130 . In step S 340 , the output circuit  140  receives the disturbed data and provides the disturbed data to the image processing circuit  13 . The image processing circuit  130  may generate compensated pixel data according to the sensing data to provide to the driving circuit  12 . The driving circuit  12  converts the compensated pixel data into a driving voltage and outputs the driving voltage to the corresponding data line (e.g., the data line Ld illustrated in  FIG. 1 ) of the display panel  11 . Thereby, performance decline of an OLED may be effectively compensated. 
       FIG. 4  is a schematic waveform diagram illustrating output signals of the ADC circuit  120  and the disturbance circuit  130  depicted in  FIG. 1  according to an embodiment of the invention. In  FIG. 4 , the horizontal axis represents the time, and the vertical axis represents voltages. A curve  401  illustrated in  FIG. 4  represents the sensing signal output by the sensing circuit  110 , and a dotted line  402  represents a threshold voltage level for the ADC circuit  120  to perform an analog-to-digital converter operation. A curve  403  represents the least-significant-bit of the sensing data output by the ADC circuit  120 . A curve  404  represents the disturbed data output by the disturbing circuit  130 . When the curve  401  (representing the sensing signal) is greater than the dotted line  402 , it is assumed that the sensing data (represented by the curve  403 ) output by the ADC circuit  120  is “0001”. When the curve  401  (representing the sensing signal) is less than the dotted line  402 , the sensing data (represented by the curve  403 ) is changed from “0001” to “0000”. A quantization error exists in a transition state of the sensing data. The disturbing circuit  130  may load the time-variant disturbance component to the transition state of the sensing data (represented by the curve  403 ) to generate the disturbed data (represented by the curve  404 ). In terms of average energy, the time-variant disturbance component may turn a change of digital data to be smoother. Based on the nature of persistence of vision of human eyes, a user is prevented from observing the time-variant disturbance component on an image displayed by the display panel. Thus, the sensing apparatus  100  may mitigate image abnormality resulting from the quantization and/or non-linear error. 
       FIG. 5  is a schematic circuit block diagram illustrating the sensing apparatus depicted in  FIG. 1  according to an embodiment of the invention. It is noted that the circuit illustrated in  FIG. 6  is explained with application to  FIG. 1  but is not limited to being applied to the configuration shown in  FIG. 1 . In the embodiment illustrated in  FIG. 5 , the sensing circuit  110  includes a sampling circuit  111  and a gain amplifier  112 . The sampling circuit  111  is coupled to the corresponding sensing line (e.g., the sensing line Ls illustrated in  FIG. 1 ) of the display panel  11 . The sampling circuit  111  may sample the sensing result of the sensing line Ls to obtain a sampling result. The gain amplifier  112  is coupled to the sampling circuit  111  to receive the sampling result. The gain amplifier  112  outputs the sensing signal related to the sampling result to the ADC circuit  120 . For example, the gain amplifier  112  gains the sampling result by a gain value which serves as the sensing signal. Based on a design requirement, the gain value may be any real number, for example, a positive number, a negative number or 1. The implementation manners of the sampling circuit  111  and the gain amplifier  112  are not limited in the present embodiment. For example, the sampling circuit  111  may be a conventional sampling circuit or other sampling circuits/elements, and the gain amplifier  112  may be a conventional gain amplifier or other gain circuits/elements. In some embodiments, the gain amplifier  112  may be integrated into the ADC circuit  120  based on a design requirement. In some other embodiments, the gain amplifier  112  may be omitted based on a design requirement. 
     In the embodiment illustrated in  FIG. 5 , the ADC circuit  120  includes an analog-to-digital converter (ADC)  121 . An input terminal of the ADC  121  is coupled to the sensing circuit  110  to receive the sensing signal. An output terminal of the ADC  121  outputs the sensing data related to the sensing signal to the disturbing circuit  130 . The implementation manner of the ADC  121  is not limited in the invention. For example, the ADC  121  may have any configurations known in the art or other ADC circuits/elements. 
     In the embodiment illustrated in  FIG. 5 , the disturbing circuit  130  includes a noise generating circuit  131  and an adding/subtracting circuit  132 . The noise generating circuit  131  may generate a noise to the adding/subtracting circuit  132  and serves the noise as the time-variant disturbance component. A time average value of the noise (i.e., the time-variant disturbance component) is preferably a constant. Based on a design requirement, the constant may be any real number, for example, a positive number, a negative number or 0. The implementation manner of the noise generating circuit  131  is not limited in the present embodiment. For example, the noise generating circuit  131  may include a delta-sigma modulator, a Gaussian noise generator or a pseudo random bit sequence (PRBS) generator or other noise generating circuits/elements. Based on a design requirement, the delta-sigma modulator includes a multi-stage noise shaping (MASH) circuit or other modulation circuits/elements. Based on a design requirement, the PRBS generator includes a white-noise generator or other noise generating circuits/elements. 
     The adding/subtracting circuit  132  is coupled to the ADC circuit  120  to receive the sensing data. The adding/subtracting circuit  132  is coupled to the noise generating circuit  131  to receive the noise. The adding/subtracting circuit  132  adds (or subtracts) the noise (i.e., the time-variant disturbance component) into (or from) the sensing data to output the disturbed data to the output circuit  140 . 
     In the embodiment illustrated in  FIG. 5 , the output circuit  140  includes a latch  141  and a transmitter interface circuit  142 . An input terminal of the latch  141  is coupled to the disturbing circuit  130  to receive the disturbed data. The latch  141  latches the disturbed data to output latched data to the transmitter interface circuit  142 . An input terminal of the transmitter interface circuit  142  is coupled to the latch  141  to receive the latched data. The transmitter interface circuit  142  is configured to transmit the latched data to an external apparatus (e.g., the image processing circuit  13  illustrated in  FIG. 5 ). The implementation manners of the latch  141  and the transmitter interface circuit  142  are not limited in the present embodiment. For example, the latch  141  may be have any configuration known in the art or other latch circuits/elements, and the transmitter interface circuit  142  may have any configuration known in the art or other transmitter circuits/elements. 
       FIG. 6  is a schematic circuit block diagram illustrating the sensing apparatus  100  depicted in  FIG. 1  according to an embodiment of the invention. It is noted that the circuit illustrated in  FIG. 6  is explained with application to  FIG. 1  but is not limited to being applied to the configuration shown in  FIG. 1 . The sensing circuit  110  illustrated in  FIG. 6  may refer to the description related to  FIG. 5  and thus, will not be repeated. In the embodiment illustrated in  FIG. 6 , the ADC circuit  120  includes an ADC  121  and a latch  122 . An input terminal of the ADC  121  is coupled to the sensing circuit  110  to receive the sensing signal. An output terminal of the ADC  121  outputs digital data related to the sensing signal to the disturbing circuit  122 . An input terminal of the latch  122  is coupled to the output terminal of the ADC  121  to receive the digital data. The latch  122  latches the digital data to output latched data which serves as the sensing data and is provided to the disturbing circuit  130 . The implementation manners of the ADC  121  and the latch  122  are not limited in the invention. For example, the ADC  121  may have any configuration known in that art or other ADC circuits/elements, and the latch  122  may have any configuration known in the art or other latch circuits/elements. 
     In the embodiment illustrated in  FIG. 6 , the disturbing circuit  130  includes a noise generating circuit  131  and an adding/subtracting circuit  132 . The adding/subtracting circuit  132  is coupled to an output terminal of the latch  122  to receive the sensing data. The noise generating circuit  131  and the adding/subtracting circuit  132  illustrated in  FIG. 6  may be inferred with reference to the description related to  FIG. 5  and thus, will not be repeated. 
     In the embodiment illustrated in  FIG. 6 , the output circuit  140  includes a transmitter interface circuit  142 . An input terminal of the transmitter interface circuit  142  is coupled to an output terminal of the adding/subtracting circuit  132  of the disturbing circuit  130  to receive the disturbed data. The transmitter interface circuit  142  is configured to transmit the disturbed data to an external apparatus (e.g., the image processing circuit  13  illustrated in  FIG. 6 ). The transmitter interface circuit  142  illustrated in  FIG. 6  may be inferred with reference to the description related to  FIG. 5  and thus, will not be repeated. 
     Based on the above, in the sensing apparatus and the operating method of the embodiments of the invention, the time-variant disturbance component can be employed to disturb the sensing data output by the analog-to-digital converter circuit, so as to generate the disturbed data. Thus, the sensing apparatus can mitigate the image abnormality resulting from the quantization and/or non-linear error. 
     Although the invention has been disclosed by the above embodiments, they are not intended to limit the invention. It will be apparent to one of ordinary skill in the art that modifications and variations to the invention may be made without departing from the spirit and scope of the invention. Therefore, the scope of the invention will be defined by the appended claims.