This application claims priority to Taiwanese Patent Application No. 110147451, filed on Dec. 17, 2021.
The disclosure relates to display technology, and more particularly to a scan-type display apparatus capable of short circuit detection and a data driver thereof.
Although conventional methods for driving a light emitting diode (LED) display to emit light in a line scan manner may alleviate ghosting phenomenon and cross-channel coupling problems of the LED display, it may cause other problems such as short circuit caterpillar phenomenon. For each LED of the LED display, charges released by parasitic capacitance across the LED may flow through the LED, so as to cause the LED to emit light. This unexpected light emission of the LED is the so called ghosting phenomenon. For each line of the line scan of an LED array of the LED display, a dark pixel of the line may be affected by a bright pixel of the line to produce a brightness different from what would be expected. This is the so called cross-channel coupling problem. The short circuit caterpillar phenomenon includes the always bright caterpillar phenomenon and the always dark caterpillar phenomenon. A short circuit of an LED in the LED array of the LED display may cause that LED and other LEDs in the same column of the LED array to be always bright. This is the so called always bright caterpillar phenomenon. Similarly, a short circuit of an LED in the LED array of the LED display may cause that LED and other LEDs in the same column of the LED array to be always dark. This is the so called always dark caterpillar phenomenon. Therefore, the short circuit caterpillar phenomenon degrades the display quality of the LED display.
Therefore, an object of the disclosure is to provide a scan-type display apparatus capable of short circuit detection and a data driver thereof. The scan-type display apparatus can alleviate the drawback of the prior art.
According to an aspect of the disclosure, the scan-type display apparatus includes a light emitting diode (LED) array and a data driver. The LED array has a common anode configuration, and includes a plurality of scan lines, a plurality of data lines and a plurality of LEDs. The LEDs are arranged in a matrix that has a plurality of rows respectively corresponding to the scan lines and a plurality of columns respectively corresponding to the data lines. With respect to each of the rows, anodes of the LEDs in the row are connected to the scan line that corresponds to the row. With respect to each of the columns, cathodes of the LEDs in the column are connected to the data line that corresponds to the column. The data driver includes a plurality of data driving circuits that respectively correspond to the data lines. Each of the data driving circuits includes a current driver and a detector. The current driver has an output terminal that is connected to the data line corresponding to the data driving circuit, receives a pulse width control signal, and outputs one of a drive current and a clamp voltage at the output terminal of the current driver based on the pulse width control signal. The detector is connected to the current driver to receive a feed-in voltage related to a voltage at the output terminal of the current driver, further receives a detection timing signal, and generates a detection signal that indicates whether any one of the LEDs connected to the data line corresponding to the data driving circuit is short circuited based on the feed-in voltage and the detection timing signal.
According to another aspect of the disclosure, the data driver is adapted to be used in a scan-type display apparatus that includes a light emitting diode (LED) array. The LED array has a common anode configuration, and includes a plurality of data lines and a plurality of LEDs. Each of the LEDs is connected to a corresponding one of the data lines. The data driver includes a plurality of data driving circuits that respectively correspond to the data lines. Each of the data driving circuits includes a current driver and a detector. The current driver has an output terminal that is connected to the data line corresponding to the data driving circuit, receives a pulse width control signal, and outputs one of a drive current and a clamp voltage at the output terminal of the current driver based on the pulse width control signal. The detector is connected to the current driver to receive a feed-in voltage related to a voltage at the output terminal of the current driver, further receives a detection timing signal, and generates a detection signal that indicates whether any one of the LEDs connected to the data line corresponding to the data driving circuit is short circuited based on the feed-in voltage and the detection timing signal.
Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiment(s) with reference to the accompanying drawings. It is noted that various features may not be drawn to scale.
Before the disclosure is described in greater detail, it should be noted that where considered appropriate, reference numerals or terminal portions of reference numerals have been repeated among the figures to indicate corresponding or analogous elements, which may optionally have similar characteristics.
Referring to
The LED array 1 has a common anode configuration, and includes a number (N) of scan lines 111, a number (M) of data lines 112 and a number (N×M) of LEDs 113, where N≥2 and M≥2. The LEDs 113 are arranged in a matrix that has a number (N) of rows respectively corresponding to the scan lines 111 and a number (M) of columns respectively corresponding to the data lines 112.
With respect to each of the rows, anodes of the LEDs 113 in the row are connected to the scan line 111 that corresponds to the row. With respect to each of the columns, cathodes of the LEDs 113 in the column are connected to the data line 112 that corresponds to the column. For illustration purposes, in this embodiment, the LEDs 113 in an nth one of the rows is adjacent to the LEDs 113 in an (n−1)th one of the rows, and the LEDs 113 in an mth one of the columns is adjacent to the LEDs 113 in an (m−1)th one of the columns, where 2≤n≤N and 2≤m≤M.
The scan driver 2 includes a number (N) of scan driving circuits 21 and a scan controller 22. The scan driving circuits 21 respectively correspond to the scan lines 111.
The scan controller 22 receives a number (M) of detection signals (Dr1-DrM), and generates a number (N) of scan signals (SC1-SCN) that respectively correspond to the scan driving circuits 21 and a number (N) of clamp signals (CS1-CSN) that respectively correspond to the scan driving circuits 21, with the clamp signals (CS1-CSN) dependent on the detection signals (Dr1-DrM).
Each of the scan driving circuits 21 is connected to the corresponding scan line 111, and is further connected to the scan controller 22 to receive the corresponding scan signal (SCk) and the corresponding clamp signal (CSk), and further receives an input voltage (Vin), where 1≤k≤N. Each of the scan driving circuits 21 is operable to output or not output the input voltage (Vin) to the corresponding scan line 111 based on the corresponding scan signal (SCk), and is operable to output or not output a clamp voltage (Vc2) to the corresponding scan line 111 based on the corresponding clamp signal (CSk). The clamp voltage (Vc2) is used to eliminate ghosting phenomenon and cross-channel coupling problems of the LED array 1, and is known to those skilled in the art, so details of the clamp voltage (Vc2) are omitted herein for the sake of brevity.
In this embodiment, each of the scan driving circuits 21 includes a scan switch 211, a voltage regulator 212 and a clamp switch 213. The scan switch 211 has a first terminal that receives the input voltage (Vin), a second terminal that is connected to the corresponding scan line 111, and a control terminal that receives the corresponding scan signal (SCk). The scan switch 211 transitions between conduction and non-conduction based on the corresponding scan signal (SCk), and, when conducting, permits transmission of the input voltage (Vin) therethrough to the corresponding scan line 111. The voltage regulator 212 generates the clamp voltage (Vc2). The clamp switch 213 has a first terminal that is connected to the voltage regulator 212 to receive the clamp voltage (Vc2), a second terminal that is connected to the second terminal of the scan switch 211, and a control terminal that receives the corresponding clamp signal (CSk). The clamp switch 213 transitions between conduction and non-conduction based on the corresponding clamp signal (CSk), and, when conducting, permits transmission of the clamp voltage (Vc2) therethrough to the corresponding scan line 111. The scan switch 211 and the clamp switch 213 conduct one at a time.
For illustration purposes, in this embodiment, the second terminal of the scan switch 211 of a kth one of the scan driving circuits 21 is connected to the scan line 111 that is connected to the LEDs 113 in a kth one of the rows; and the scan switch 211 and the clamp switch 213 of the kth one of the scan driving circuits 21 are respectively controlled by the scan signal (SCk) and the clamp signal (CSk), where 1≤k≤N.
The data driver 3 includes a number (M) of data driving circuits 31 and a pulse width controller 32. The data driving circuits 31 respectively correspond to the data lines 112. Each of the data driving circuits 31 includes a current driver 311 and a detector 312.
With respect to each of the data driving circuits 31, the current driver 311 has an output terminal (Q1) that is connected to the corresponding data line 112, receives a pulse width control signal (Pcj), and outputs one of a drive current (Id) and a clamp voltage (Vc1) at the output terminal (Q1) of the current driver 311 based on the pulse width control signal (Pcj), where 1≤j≤M.
In this embodiment, with respect to each of the data driving circuits 31, the current driver 311 includes a voltage regulator 313, an inverter 314, a constant current generator 315, a first switch 316 and a second switch 317. The voltage regulator 313 generates the clamp voltage (Vc1). The inverter 314 receives the pulse width control signal (Pcj), and generates an inverted control signal (Is) that is a logical complement of the pulse width control signal (Pcj) in logic value. The constant current generator 315 generates the drive current (Id). The first switch 316 has a first terminal that is connected to the output terminal (Q1) of the current driver 311, a second terminal that is connected to the constant current generator 315, and a control terminal that receives the pulse width control signal (Pcj). The first switch 316 transitions between conduction and non-conduction based on the pulse width control signal (Pcj), and, when conducting, permits flow of the drive current (Id) therethrough from the output terminal (Q1) of the current driver 311 to the constant current generator 315. The second switch 317 has a first terminal that is connected to the voltage regulator 313, a second terminal that is connected to the output terminal (Q1) of the current driver 311, and a control terminal that is connected to the inverter 314 to receive the inverted control signal (Is). The second switch 317 transitions between conduction and non-conduction based on the inverted control signal (Is), and, when conducting, permits transmission of the clamp voltage (Vc1) therethrough from the voltage regulator 313 to the output terminal (Q1) of the current driver 311.
With respect to each of the data driving circuits 31, the detector 312 is connected to the output terminal (Q1) of the current driver 311, receives a voltage at the output terminal (Q1) of the current driver 311 to serve as a feed-in voltage, further receives a detection timing signal (DTj), and generates a detection signal (Drj) that indicates whether any one of the LEDs 113 connected to the corresponding data line 112 is short circuited based on the feed-in voltage and the detection timing signal (DTj), where 1≤j≤M.
In this embodiment, with respect to each of the data driving circuits 31, the detector 312 includes a comparator 318 and a logic gate 319. The comparator 318 has a first input terminal (e.g., a non-inverting input terminal) that is connected to the output terminal (Q1) of the current driver 311 to receive the feed-in voltage, a second input terminal (e.g., an inverting input terminal) that receives a predetermined reference voltage (Vr), and an output terminal that provides a comparison signal (Cr). The comparison signal (Cr) indicates a result of a comparison between the feed-in voltage and the predetermined reference voltage (Vr). The logic gate 319 (e.g., an AND gate) has a first input terminal that is connected to the output terminal of the comparator 318 to receive the comparison signal (Cr), a second input terminal that receives the detection timing signal (DTj), and an output terminal that provides the detection signal (Drj).
For illustration purposes, in this embodiment, the output terminal (Q1) of the current driver 311 of a jth one of the data driving circuits 31 is connected to the data line 112 that is connected to the LEDs 113 in a jth one of the columns; the first and second switches 316, 317 of the current driver 311 of the jth one of the data driving circuits 31 are controlled by the pulse width control signal (Pcj); and the logic gate 319 of the detector 312 of the jth one of the data driving circuits 31 receives the detection timing signal (DTj) and provides the detection signal (Drj), where 1≤j≤M.
In this embodiment, the pulse width controller 32 is connected to the scan controller 22, the inverters 314 and the control terminals of the first switches 316 of the current drivers 311 of the data driving circuits 31, and the second input terminals and the output terminals of the logic gates 319 of the detectors 312 of the data driving circuits 31. The pulse width controller 32 generates the pulse width control signals (Pc1-PcM) to be respectively received by the inverters 314 and to be respectively received by the control terminals of the first switches 316, and the detection timing signals (DT1-DTM) to be respectively received by the second input terminals of the logic gates 319. The pulse width controller 32 receives the detection signals (Dr1-DrM) respectively generated by the detectors 312 from the output terminals of the logic gates 319, and outputs the detection signals (Dr1-DrM) respectively received from the detectors 312 for receipt by the scan controller 22.
As shown in
As shown in
When the clamp signals (CS1-CSN) (i.e., CS1-CS4 in this embodiment) have waveforms as shown in
It should be noted that, in a design phase of the scan-type display apparatus of this embodiment, the widths of the pulses of the detection timing signals (DT1-DTM) should be properly selected based on a magnitude of the predetermined reference voltage (Vr). As shown in
Referring to
In the second embodiment, with respect to each of the data driving circuits 31, the first input terminal of the comparator 318 is connected to the second terminal of the first switch 316, instead of to the output terminal (Q1) of the current driver 311, and receives a voltage at the second terminal of the first switch 316 to serve as the feed-in voltage. In addition, the width of the pulse of the detection timing signal (DTj) that corresponds to the kth one of the scan driving circuits 21 is smaller than or equal to the width of the pulse of the pulse width control signal (Pcj) that corresponds to the kth one of the scan driving circuits 21, where 1≤j≤M and 1≤k≤N.
Referring to
In the third embodiment, the pulse width controller 3 is not connected to the output terminals of the logic gates 319 of the detectors 312 of the data driving circuits 31, and does not receive the detection signals (Dr1-DrM) respectively generated by the detectors 312 from the output terminals of the logic gates 319. The scan controller 22 is connected to the output terminals of the logic gates 319, instead of to the pulse width controller 32, and receives the detection signals (Dr1-DrM) respectively generated by the detectors 312 from the output terminals of the logic gates 319.
Referring to
In the fourth embodiment, the scan-type display apparatus includes a scan driver 2, a number (S) of data drivers 3 and a number (S) of LED arrays 1, where S≥2. The LED arrays 1 are arranged in a matrix that has a row corresponding to the scan driver 2 and a number (S) of columns respectively corresponding to the data drivers 3. With respect to the row of the LED arrays 1, the second terminals of the scan switches 211 of the scan driving circuits 21 of the corresponding scan driver 2 are respectively connected to the scan lines 111 of each of the LED arrays 1 in the row. With respect to each of the columns of the LED arrays 1, the output terminals (Q1) of the current drivers 311 of the data driving circuits 31 of the corresponding data driver 2 are respectively connected to the data lines 112 of the LED array 1 in the column. The pulse width controllers 32 of the data drivers 3 are in a cascade connection. The scan controller 22 is connected to the pulse width controller 32 of an Sth one of the data drivers 3. The pulse width controller 32 of a first one of the data drivers 3 outputs the detection signals respectively generated by the data driving circuits 31 of the first one of the data drivers 3. The pulse width controller 32 of an sth one of the data drivers 3 receives the detection signals outputted by the pulse width controller 32 of an (s−1)th one of the data drivers 3, and outputs the detection signals received from the pulse width controller 32 of the (s−1)th one of the data drivers 3 and the detection signals respectively generated by the data driving circuits 31 of the sth one of the data drivers 3, where 2≤s≤S−1. The pulse width controller 32 of the Sth one of the data drivers 3 receives the detection signals outputted by the pulse width controller 32 of an (S−1)th one of the data drivers 3, and outputs the detection signals received from the pulse width controller 32 of the (S−1)th one of the data drivers 3 and the detection signals respectively generated by the data driving circuits 31 of the Sth one of the data drivers 3 for receipt by the scan controller 22.
Referring to
In the fifth embodiment, the scan-type display apparatus includes a number (R) of scan drivers 2, a number (S) of data drivers 3 and a number (R×S) of LED arrays 1, where R≥2 and S≥2. The LED arrays 1 are arranged in a matrix that has a number (R) of rows respectively corresponding to the scan driver 2 and a number (S) of columns respectively corresponding to the data drivers 3. With respect to each of the rows of the LED arrays 1, the second terminals of the scan switches 211 of the scan driving circuits 21 of the corresponding scan driver 2 are respectively connected to the scan lines 111 of each of the LED arrays 1 in the row. With respect to each of the columns of the LED arrays 1, the output terminals (Q1) of the current drivers 311 of the data driving circuits 31 of the corresponding data driver 2 are respectively connected to the data lines 112 of each of the LED arrays 1 in the column. The scan controller 22 of each of the scan drivers 2 is connected to the pulse width controller 32 of the Sth one of the data drivers 3 to receive the detection signals outputted by the Sth one of the data drivers 3.
Referring to
In the sixth embodiment, the scan controllers 22 of the scan drivers 2 are in a cascade connection, and only the scan controller 22 of a first one of the scan drivers 2 is connected to the pulse width controller 32 of the Sth one of the data drivers 3. The scan controller 22 of the first one of the scan drivers 2 receives the detection signals outputted by the pulse width controller 32 of the Sth one of the data drivers 3, and outputs the detection signals received from the pulse width controller 32 of the Sth one of the data drivers 3. The scan controller 22 of an rth one of the scan drivers 2 is connected to the scan controller 22 of an (r−1)th one of the scan drivers 2 to receive the detection signals outputted by the scan controller 22 of the (r−1)th one of the scan drivers 2, and outputs the detection signals received from the scan controller 22 of the (r−1)th one of the scan drivers 2, where 2≤r≤R−1. The scan controller 22 of an Rth one of the scan drivers 2 receives the detection signals outputted by the scan controller 22 of an (R−1)th one of the scan drivers 2.
Referring to
In the seventh embodiment, the pulse width controllers 32 of the data drivers 3 are not in a cascade connection. The pulse width controllers 32 of the sth one of the data drivers 3 does not receive the detection signals outputted by the (s−1)th one of the data drivers 3, and only outputs the detection signals respectively generated by the data driving circuits 31 of the sth one of the data drivers 3, where 2≤s≤S. The scan controller 22 of the first one of the scan drivers 2 is connected to the pulse width controllers 32 of the data drivers 3 to receive the detection signals outputted by the pulse width controllers 32 of the data drivers 3, and outputs the detection signals received from the pulse width controllers 32 of the data drivers 3.
Referring to
In the eighth embodiment, the pulse width controllers 32 of the data drivers 3 are not in a cascade connection. The pulse width controllers 32 of the sth one of the data drivers 3 does not receive the detection signals outputted by the (s−1)th one of the data drivers 3, and only outputs the detection signals respectively generated by the data driving circuits 31 of the sth one of the data drivers 3, where 2≤s≤S. The scan controller 22 is connected to the pulse width controllers 32 of the data drivers 3 to receive the detection signals outputted by the pulse width controllers 32 of the data drivers 3.
Referring to
In the ninth embodiment, the pulse width controllers 32 of the data drivers 3 are not in a cascade connection. The pulse width controllers 32 of the sth one of the data drivers 3 does not receive the detection signals outputted by the (s−1)th one of the data drivers 3, and only outputs the detection signals respectively generated by the data driving circuits 31 of the sth one of the data drivers 3, where 2≤s≤S. The scan controller 22 of each of the scan drivers 2 is connected to the pulse width controllers 32 of the data drivers 3 to receive the detection signals outputted by the pulse width controllers 32 of the data drivers 3.
Referring to
In the tenth embodiment, the scan-type display apparatus further includes a controller device 4. The controller device 4 is connected between the pulse width controller 32 of the Sth one of the data drivers 3 and the scan controller 22, receives the detection signals outputted by the pulse width controller 32 of the Sth one of the data drivers 3, and outputs the detection signals received from the pulse width controller 32 of the Sth one of the data drivers 3 for receipt by the scan controller 22.
Referring to
In the eleventh embodiment, the scan-type display apparatus further includes a controller device 4. The controller device 4 is connected between the pulse width controller 32 of the Sth one of the data drivers 3 and the scan controller 22 of each of the scan drivers 2, receives the detection signals outputted by the pulse width controller 32 of the Sth one of the data drivers 3, and outputs the detection signals received from the pulse width controller 32 of the Sth one of the data drivers 3 for receipt by the scan controller 22 of each of the scan drivers 2.
The controller device 4 receives the detection signals (Dr1-DrM, Dr1′-DrM′) outputted by the pulse width controller 32 of the second one of the data drivers 3, and outputs the detection signals (Dr1-DrM, Dr1′-DrM′) received from the pulse width controller 32 of the second one of the data drivers 3 for receipt by the scan controller 22 of each of the scan drivers 2.
Referring to
In the twelfth embodiment, the scan-type display apparatus further includes a controller device 4. The controller device 4 is connected between the pulse width controller 32 of the Sth one of the data drivers 3 and the scan controller 22 of the first one of the scan drivers 2, receives the detection signals outputted by the pulse width controller 32 of the Sth one of the data drivers 3, and outputs the detection signals received from the pulse width controller 32 of the Sth one of the data drivers 3 for receipt by the scan controller 22 of the first one of the scan drivers 2.
In each of the tenth to twelfth embodiments, the controller device 4 generates parameter settings and grayscale data that are required by the scan driver(s) 2 and the data drivers 3 to properly drive the LED arrays 1. The operations of the controller device 4 are known to those skilled in the art, and the salient features of the disclosure do not reside in these operations, so details of these operations are omitted herein for the sake of brevity.
In view of the above, for each of the first to twelfth embodiments, the scan-type display apparatus can eliminate short circuit caterpillar phenomenon of the LED array(s) 1. In addition, the data driver(s) 3 output(s) the detection signals generated by the data driving circuits 31 of the data driver(s) 3 for receipt by the scan controller(s) 22 of the scan driver(s) 2 and/or the controller device 4, so as to inform the scan controller(s) 22 of the scan driver(s) 2 and/or the controller device 4 whether any one of the LEDs 113 connected to any one of the data lines 112 is short circuited.
In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiment(s). It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects; such does not mean that every one of these features needs to be practiced with the presence of all the other features. In other words, in any described embodiment, when implementation of one or more features or specific details does not affect implementation of another one or more features or specific details, said one or more features may be singled out and practiced alone without said another one or more features or specific details. It should be further noted that one or more features or specific details from one embodiment may be practiced together with one or more features or specific details from another embodiment, where appropriate, in the practice of the disclosure.
While the disclosure has been described in connection with what is(are) considered the exemplary embodiment(s), it is understood that this disclosure is not limited to the disclosed embodiment(s) but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
Number | Date | Country | Kind |
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110147451 | Dec 2021 | TW | national |