Patent Grant
11847951
This application claims priority under 35 USC § 119 to Korean Patent Application No. 10-2022-0057807, filed on May 11, 2022, in the Korean Intellectual Property Office (KIPO), the content of which is herein incorporated by reference in its entirety.
Embodiments of the present inventive concept relate to a display device, and more particularly to a gamma voltage generator, a display driver including the gamma voltage generator, and a method of generating a gamma voltage by the gamma voltage generator.
A gamma voltage generator of a display device may receive a reference voltage, and may generate at least one gamma voltage (or at least one gamma reference voltage) by using the reference voltage. A data driver may receive the gamma voltage from the gamma voltage generator, may generate a plurality of gray voltages respectively corresponding to a plurality of gray levels based on the gamma voltage, may select gray voltages corresponding to image data among the plurality of gray voltages, and may provide the selected gray voltages as data voltages to pixels of a display panel.
However, in a case where the reference voltage has a ripple or fluctuates, the gamma voltage also may have a ripple or may fluctuate. Further, in a case where the gamma voltage has the ripple or fluctuates, the data voltages may have a ripple or may fluctuate, and thus a flicker may occur in a display device.
Some embodiments provide a gamma voltage generator capable of reducing a ripple or a fluctuation of a gamma voltage.
Some embodiments provide a display driver including a gamma voltage generator capable of reducing a ripple or a fluctuation of a gamma voltage.
Some embodiments provide a display device including a gamma voltage generator capable of reducing a ripple or a fluctuation of a gamma voltage.
Some embodiments provide a method of generating a gamma voltage capable of reducing a ripple or a fluctuation of the gamma voltage.
According to embodiments, there is provided a gamma voltage generator including a plurality of gamma generation circuits configured to generate a plurality of gamma voltages, respectively. At least one gamma generation circuit of the plurality of gamma generation circuits includes an input circuit configured to receive a first reference voltage and a second reference voltage, a reference voltage select circuit configured to select a reference voltage among the first reference voltage and the second reference voltage by comparing a gamma voltage generated by the at least one gamma generation circuit with at least one of the first reference voltage and the second reference voltage, a digital-to-analog conversion circuit configured to generate an analog voltage corresponding to a gamma code based on the reference voltage selected by the reference voltage select circuit, and an output circuit configured to output the gamma voltage based on the analog voltage.
In embodiments, the at least one gamma generation circuit may selectively receive two or more reference voltages including the first reference voltage and the second reference voltage, and each of remaining gamma generation circuits other than the at least one gamma generation circuit among the plurality of gamma generation circuits may receive a fixed reference voltage.
In embodiments, the second reference voltage may be higher than the first reference voltage. The reference voltage select circuit may select the first reference voltage among the first reference voltage and the second reference voltage in a case where the gamma voltage is less than or equal to the first reference voltage, and may select the second reference voltage among the first reference voltage and the second reference voltage in a case where the gamma voltage is greater than the first reference voltage.
In embodiments, the first reference voltage may be a band gap reference (BGR) voltage that is generated by a BGR circuit, and the second reference voltage may be a logic voltage that is higher than the BGR voltage and that is supplied to a logic circuit.
In embodiments, the input circuit may include a first input buffer configured to receive the first reference voltage through an input terminal and to output the first reference voltage through an output terminal, a second input buffer configured to receive the second reference voltage through an input terminal and to output the second reference voltage through an output terminal, a reference voltage control switch configured to selectively couple the output terminal of the first input buffer or the output terminal of the second input buffer to the digital-to-analog conversion circuit in response to a reference voltage control signal.
In embodiments, the digital-to-analog conversion circuit may include a resistor string configured to generate a plurality of analog voltages by dividing the selected reference voltage, and an analog voltage select circuit configured to select one of the plurality of analog voltages in response to the gamma code.
In embodiments, the output circuit may include an output buffer configured to receive the analog voltage, and to output the analog voltage as the gamma voltage.
In embodiments, the second reference voltage may be higher than the first reference voltage. In a case where the gamma voltage is less than or equal to the first reference voltage, the at least one gamma generation circuit may not apply a gain of the output circuit and may generate the gamma voltage by using the first reference voltage. In a case where the gamma voltage is greater than the first reference voltage and less than or equal to the second reference voltage, the at least one gamma generation circuit may not apply the gain of the output circuit and may generate the gamma voltage by using the second reference voltage. In a case where the gamma voltage is greater than the second reference voltage, the at least one gamma generation circuit may generate the gamma voltage by using the second reference voltage and by applying the gain of the output circuit.
In embodiments, the reference voltage select circuit may output the gamma voltage substantially the same as the analog voltage in a case where the gain of the output circuit is not applied, and may output the gamma voltage generated by multiplying the analog voltage by the gain of the output circuit in a case where the gain of the output circuit is applied.
In embodiments, the at least one gamma generation circuit may further include a gain control circuit configured to control the output circuit such that a gain of the output circuit is selectively applied by comparing the gamma voltage with the second reference voltage.
In embodiments, the gain control circuit may control the output circuit to output the analog voltage as the gamma voltage in a case where the gamma voltage is less than or equal to the second reference voltage, and may control the output circuit to generate the gamma voltage by multiplying the analog voltage by the gain of the output circuit in a case where the gamma voltage is greater than the second reference voltage.
In embodiments, the output circuit may include an output buffer including a first input terminal for receiving the analog voltage, a second input terminal coupled to a feedback node, and an output terminal coupled to an output node at which the gamma voltage is output, a first resistor including a first terminal coupled to the output node, and a second terminal coupled to the feedback node, a second resistor including a first terminal coupled to the feedback node, and a second terminal, and a gain application switch configured to selectively couple the second terminal of the second resistor to a power supply voltage line in response to a gain application signal output from the gain control circuit.
In embodiments, the input circuit may include an input buffer including an input terminal, and an output terminal coupled to the digital-to-analog conversion circuit, and a reference voltage select switch configured to selectively couple a line of the first reference voltage or a line of the second reference voltage to the input terminal of the input buffer in response to a reference voltage control signal.
In embodiments, the input circuit may receive L reference voltages including the first reference voltage and the second reference voltage, where L is an integer greater than 1, and the reference voltage select circuit may select the reference voltage among the L reference voltages by comparing the gamma voltage with the L reference voltages.
In embodiments, the at least one gamma generation circuit may further include a gain control circuit configured to generate a gain value adjustment signal for adjusting a value of a gain of the output circuit, and a gain application signal for selectively applying the gain of the output circuit by comparing the gamma voltage with the second reference voltage.
In embodiments, the output circuit may include an output buffer including a first input terminal for receiving the analog voltage, a second input terminal coupled to a feedback node, and an output terminal coupled to an output node at which the gamma voltage is output, a first resistor including a first terminal coupled to the output node, and a second terminal coupled to the feedback node, and having a variable resistance value that is changed in response to the gain value adjustment signal, a second resistor including a first terminal coupled to the feedback node, and a second terminal, and a gain application switch configured to selectively couple the second terminal of the second resistor to a power supply voltage line in response to the gain application signal.
In embodiments, the plurality of gamma generation circuits may be N gamma generation circuits, where N is an integer greater than 1. Each of M gamma generation circuits among the N gamma generation circuits may selectively receive two or more reference voltages, where M is an integer greater than 0 and less than N, and each of N-M gamma generation circuits other than the M gamma generation circuits among the N gamma generation circuits may receive a fixed reference voltage.
According to embodiments, there is provided a display driver for driving a display panel. The display driver includes a gamma voltage generator including a plurality of gamma generation circuits that respectively generate a plurality of gamma voltages, and a data driver configured to generate data voltages based on the plurality of gamma voltages and to provide the data voltages to the display panel. At least one gamma generation circuit of the plurality of gamma generation circuits includes an input circuit configured to receive a first reference voltage and a second reference voltage, a reference voltage select circuit configured to select a reference voltage among the first reference voltage and the second reference voltage by comparing a gamma voltage generated by the at least one gamma generation circuit with the first reference voltage and the second reference voltage, a digital-to-analog conversion circuit configured to generate an analog voltage corresponding to a gamma code based on the reference voltage selected by the reference voltage select circuit, and an output circuit configured to output the gamma voltage based on the analog voltage.
In embodiments, the second reference voltage may be higher than the first reference voltage. The at least one gamma generation circuit may further include a gain control circuit configured to control the output circuit such that a gain of the output circuit is selectively applied by comparing the gamma voltage with the second reference voltage. In a case where the gamma voltage is less than or equal to the first reference voltage, the at least one gamma generation circuit may generate the gamma voltage by using the first reference voltage. In a case where the gamma voltage is greater than the first reference voltage and less than or equal to the second reference voltage, the at least one gamma generation circuit may generate the gamma voltage by using the second reference voltage. In a case where the gamma voltage is greater than the second reference voltage, the at least one gamma generation circuit may generate the gamma voltage by using the second reference voltage and by applying the gain of the output circuit.
According to embodiments, there is provided a display device including a display panel including a plurality of pixels, a scan driver configured to provide scan signals to the plurality of pixels, a gamma voltage generator including a plurality of gamma generation circuits that respectively generate a plurality of gamma voltages, a data driver configured to generate data voltages based on the plurality of gamma voltages, and to provide the data voltages to the plurality of pixels, and a controller configured to control the scan driver, the gamma voltage generator and the data driver. At least one gamma generation circuit of the plurality of gamma generation circuits includes an input circuit configured to receive a first reference voltage and a second reference voltage, a reference voltage select circuit configured to select a reference voltage among the first reference voltage and the second reference voltage by comparing a gamma voltage generated by the at least one gamma generation circuit with the first reference voltage and the second reference voltage, a digital-to-analog conversion circuit configured to generate an analog voltage corresponding to a gamma code based on the reference voltage selected by the reference voltage select circuit, and an output circuit configured to output the gamma voltage based on the analog voltage.
In embodiments, the second reference voltage may be higher than the first reference voltage. The at least one gamma generation circuit may further include a gain control circuit configured to control the output circuit such that a gain of the output circuit is selectively applied by comparing the gamma voltage with the second reference voltage. In a case where the gamma voltage is less than or equal to the first reference voltage, the at least one gamma generation circuit may generate the gamma voltage by using the first reference voltage. In a case where the gamma voltage is greater than the first reference voltage and less than or equal to the second reference voltage, the at least one gamma generation circuit may generate the gamma voltage by using the second reference voltage. In a case where the gamma voltage is greater than the second reference voltage, the at least one gamma generation circuit may generate the gamma voltage by using the second reference voltage and by applying the gain of the output circuit.
According to embodiments, there is provided a method of generating a gamma voltage. In the method, a first reference voltage and a second reference voltage are received, a gamma voltage is compared with at least one of the first reference voltage and the second reference voltage, the gamma voltage is generated by using the first reference voltage in a case where the gamma voltage is less than or equal to the first reference voltage, the gamma voltage is generated by using the second reference voltage in a case where the gamma voltage is greater than the first reference voltage and less than or equal to the second reference voltage, and the gamma voltage is generated by using the second reference voltage and by applying a gain of an output circuit in a case where the gamma voltage is greater than the second reference voltage.
As described above, in a gamma voltage generator, a display driver, a display device and a method of generating a gamma voltage, at least one gamma generation circuit that generates at least one gamma voltage of a plurality of gamma voltages generated by the gamma voltage generator may receive a plurality of reference voltages, may select one reference voltage among the plurality of reference voltages by comparing the at least one gamma voltage with the plurality of reference voltages, and may generates the at least one gamma voltage by using the selected one reference voltage. Accordingly, a ripple or a fluctuation of the at least one gamma voltage may be reduced, a ripple or a fluctuation of data voltages generated based on the at least one gamma voltage may be reduced, and thus a flicker of the display device may be reduced.
Illustrative, non-limiting embodiments will be more clearly understood from the following detailed description in conjunction with the accompanying drawings.
Hereinafter, embodiments of the present inventive concept will be explained in detail with reference to the accompanying drawings.
Referring to
At least one gamma generation circuit 200a of the plurality of gamma generation circuits 120_1, . . . , 120_N−1 and 200a may receive two or more reference voltages VREF1 and VREF2, and may generate a gamma voltage VGMAN by selectively using the two or more reference voltages VREF1 and VREF2. Further, each of the remaining gamma generation circuits 120_1, . . . , 120_N−1 other than the least one gamma generation circuit 200a among the plurality of gamma generation circuits 120_1, . . . , 120_N−1 and 200a may receive a fixed reference voltage VREF, and may generate a gamma voltage VGMA1, . . . , VGMAN−1 by using the fixed reference voltage VREF. In some embodiments, as illustrated in
Each of the first through (N−1)-th gamma generation circuits 120_1, . . . , 120_N−1 may include an input circuit 140_1, . . . , 140_N−1, a digital-to-analog conversion (DAC) circuit 160_1, . . . , 160_N−1 and an output circuit 180_1, . . . , 180_N−1.
The input circuit 140_1, . . . , 140_N−1 of each of the first through (N−1)-th gamma generation circuits 120_1, . . . , 120_N−1 may receive a reference voltage VREF, and may provide the reference voltage VREF to the DAC circuit 160_1, . . . , 160_N−1. According to embodiments, the reference voltage VREF may be, but not be limited to, an analog power supply voltage AVDD that is supplied to an analog circuit of a data driver included in a display device, or an analog voltage generated by a dedicated DAC circuit different from the DAC circuit 160_1, . . . , 160_N−1. The analog power supply voltage AVDD or the analog voltage generated by the dedicated DAC circuit may have a ripple. In some embodiments, as illustrated in
The DAC circuit 160_1, . . . , 160_N−1 of each of the first through (N−1)-th gamma generation circuits 120_1, . . . , 120_N−1 may generate an analog voltage corresponding to a gamma code GCODE1, . . . , GCODEN−1 received from a controller included in the display device based on the reference voltage VREF received from the input circuit 140_1, . . . , 140_N−1. For example, the DAC circuit 160_1 of the first gamma generation circuit 120_1 may generate an analog voltage corresponding to a first gamma code GCODE1 based on the reference voltage VREF received from the input circuit 140_1, and the DAC circuit 160_N−1 of the (N−1)-th gamma generation circuit 120_N−1 may generate an analog voltage corresponding to an (N−1)-th gamma code GCODEN−1 based on the reference voltage VREF received from the input circuit 140_N−1. In some embodiments, as illustrated in
Each output circuit 180_1, . . . , 180_N−1 of the first through (N−1)-th gamma generation circuits 120_1, . . . , 120_N−1 may output a gamma voltage VGMA1, . . . , VGMAN−1 based on the analog voltage received from the DAC circuit 160_1, . . . , 160_N−1. Each output circuit 180_1, . . . , 180_N−1 may include an output buffer 182 that receives the analog voltage from the DAC circuit 160_1, . . . , 160_N−1, and that outputs the gamma voltage VGMA1, . . . , VGMA_N−1. In some embodiments, the output buffer 182 may receive, as a power supply voltage, an input voltage VIN provided from an external device (e.g., a host), or the analog power supply voltage AVDD that is supplied to the analog circuit of the data driver. However, the power supply voltage of the output buffer 182 is not limited to the input voltage VIN and the analog power supply voltage AVDD.
In some embodiments, each output circuit 180_1, . . . , 180_N−1 may generate the gamma voltage VGMA1, . . . , VGMA_N−1 by multiplying the analog voltage received from the DAC circuit 160_1, . . . , 160_N−1 by a predetermined gain (e.g., a gain of 5 in an example of
In other embodiments, the output circuit 180_1, . . . , 180_N−1 of each of the first through (N−1)-th gamma generation circuits 120_1, . . . , 120_N−1 may have no gain (or may have a gain of 1), and may output, as the gamma voltage VGMA1, . . . , VGMAN−1, the analog voltage received from the DAC circuit 160_1, . . . , 160_N−1. In this case, each output circuit 180_1, . . . , 180_N−1 may include only the output buffer 182 without the voltage divider 4R and R.
In some embodiments, an output terminal of the output circuit 180_1, . . . , 180_N−1 of each of the first through (N−1)-th gamma generation circuits 120_1, . . . , 120_N−1 may be coupled to an output capacitor OC1, . . . , OCN−1. The output capacitor OC1, . . . , OCN−1 may be used to stabilize the gamma voltage VGMA1, . . . , VGMAN−1 output at the output terminal. In some embodiments, the output capacitor OC1, . . . , OCN−1 may be located outside the gamma voltage generator 100a or outside the PMIC including the gamma voltage generator 100a. However, a location of the output capacitor OC1, . . . , OCN−1 is not limited thereto.
Although
The N-th gamma generation circuit 200a may include an input circuit 220a, a reference voltage select circuit 240a, a DAC circuit 260 and an output circuit 280a. Unlike each of the first through (N−1)-th gamma generation circuits 120_1, . . . , 120_N−1, the N-th gamma generation circuit 200a may receive two or more reference voltages VREF1 and VREF2, and may further include the reference voltage select circuit 240a that selects one of the two or more reference voltages VREF1 and VREF2.
The input circuit 220a may receive a first reference voltage VREF1, and a second reference voltage VREF2 higher than the first reference voltage VREF1, and may provide a reference voltage selected by the reference voltage select circuit 240a among the first reference voltage VREF1 and the second reference voltage VREF2 to the DAC circuit 260. Compared with the analog power supply voltage AVDD or the analog voltage generated by the dedicated DAC circuit that may be used as the reference voltage VREF for the first through (N−1)-th gamma generation circuits 120_1, . . . , 120_N−1, the first reference voltage VREF1 and the second reference voltage VREF2 may have a relatively small ripple. In some embodiments, the first reference voltage VREF1 may be, but not be limited to, a band gap reference (BGR) voltage VBGR that is generated by a BGR circuit, and the second reference voltage VREF2 may be, but not be limited to, the logic voltage VL that is higher than the BGR voltage VBGR and that is supplied to the logic circuit of the PMIC.
In some embodiments, the input circuit 220a may selectively output the first reference voltage VREF1 or the second reference voltage VREF2 in response to a reference voltage control signal SRVC received from the reference voltage select circuit 240a. For example, as illustrated in
The reference voltage select circuit 240a may select one reference voltage among the first reference voltage VREF1 and the second reference voltage VREF2 by comparing the gamma voltage VGMAN with at least one of the first reference voltage VREF1 and the second reference voltage VREF2. In some embodiments, in a case where the second reference voltage VREF2 is higher than the first reference voltage VREF1, the reference voltage select circuit 240a may select one of the first and second reference voltages VREF1 and VREF2 by comparing the gamma voltage VGMAN with the first reference voltage VREF1. The reference voltage select circuit 240a may select the first reference voltage VREF1 among the first reference voltage VREF1 and the second reference voltage VREF2 in a case where the gamma voltage VGMAN is less than or equal to the first reference voltage VREF1, and may select the second reference voltage VREF2 among the first reference voltage VREF1 and the second reference voltage VREF2 in a case where the gamma voltage VGMAN is greater than the first reference voltage VREF1. For example, in the case where the gamma voltage VGMAN is less than or equal to the first reference voltage VREF1, the reference voltage select circuit 240a may generate the reference voltage control signal SRVC having a first level, the reference voltage control switch RVCSWa may couple the first input buffer IB1 to the DAC circuit 260 in response to the reference voltage control signal SRVC having the first level, and the DAC circuit 260 may receive the first reference voltage VREF1 from the first input buffer IB1. Further, in the case where the gamma voltage VGMAN is greater than the first reference voltage VREF1, the reference voltage select circuit 240a may generate the reference voltage control signal SRVC having a second level, the reference voltage control switch RVCSWa may couple the second input buffer IB2 to the DAC circuit 260 in response to the reference voltage control signal SRVC having the second level, and the DAC circuit 260 may receive the second reference voltage VREF2 from the second input buffer IB2.
In some embodiments, to compare the gamma voltage VGMAN with at least one of the first reference voltage VREF1 and the second reference voltage VREF2, the reference voltage select circuit 240a may receive a gamma code GCODEN corresponding to the gamma voltage VGMAN from the controller. For example, the reference voltage select circuit 240a may previously store a code value corresponding to the first reference voltage VREF1, and may compare the gamma voltage VGMAN with the first reference voltage VREF1 by comparing the gamma code GCODEN with the stored code. In other embodiments, the reference voltage select circuit 240a may receive a select value corresponding to a result of a comparison between the gamma voltage VGMAN and the first reference voltage VREF1 from the controller, and may include a register for storing the select value. In this case, the reference voltage select circuit 240a may generate the reference voltage control signal SRVC based on the select value stored in the register.
The DAC circuit 260 may receive the reference voltage selected by the reference voltage select circuit 240a from the input circuit 220a, and may generate an analog voltage VA corresponding to the gamma code GCODEN received from the controller based on the selected reference voltage. In some embodiments, as illustrated in
The output circuit 280a may output the gamma voltage VGMAN based on the analog voltage VA received from the DAC circuit 260. In some embodiments, as illustrated in
In some embodiments, an output terminal of the output circuit 280a may be coupled to an output capacitor OCN. The output capacitor OCN may be used to stabilize the gamma voltage VGMAN output at the output terminal. In some embodiments, the output capacitor OCN may be located outside the gamma voltage generator 100a or outside the PMIC, but a location of the output capacitor OCN is not limited thereto.
Although
In a conventional gamma voltage generator, each of all gamma generation circuits may receive a fixed reference voltage, and may generate a gamma voltage by using the fixed reference voltage. Further, the conventional gamma voltage generator may use, as the fixed reference voltage, an analog power supply voltage provided to an analog circuit of a data driver or an analog voltage generated by a dedicated DAC circuit, and the analog power supply voltage or the analog voltage generated by the dedicated DAC circuit may have a ripple or may fluctuate. Thus, in the conventional gamma voltage generator, the reference voltage may have the ripple or may fluctuate, gamma voltages generated based on the reference voltage also may have a ripple or may fluctuate, data voltages generated based on the gamma voltages may have a ripple or may fluctuate, and thus a flicker may occur in an image displayed based on the data voltages. In particular, in a case where a conventional display device including the conventional gamma voltage generator display a low gray image based on the lowest gamma voltage among the gamma voltages, the flicker of the conventional display device may be intensified.
However, in the gamma voltage generator 100a according to embodiments, at least one gamma generation circuit 200a that generates at least one gamma voltage VGMAN (e.g., the lowest gamma voltage VGMAN) may receive the first and second reference voltages VREF1 and VREF2 (e.g., the BGR voltage VBGR and the logic voltage VL) having a relatively small ripple or a relatively small fluctuation compared with the reference voltage (e.g., the analog power supply voltage or the analog voltage generated by the dedicated DAC circuit) of the conventional gamma voltage generator. Accordingly, compared with the gamma voltage generated by the conventional gamma voltage generator, the gamma voltage VGMAN generated by the gamma generation circuit 200a may have a relatively small ripple or a relatively small fluctuation. Further, the gamma generation circuit 200a may select one of the first and second reference voltages VREF1 and VREF2 by comparing the gamma voltage VGMAN with at least one of the first and second reference voltages VREF1 and VREF2, and may generate the gamma voltage VGMAN by using the selected reference voltage. Thus, the gamma generation circuit 200a may generate the gamma voltage VGMAN by using an optimal reference voltage that is close to the gamma voltage VGMAN (in some embodiments, while the optimal reference voltage may be higher than or equal to the gamma voltage VGMAN). Accordingly, the ripple or the fluctuation of the gamma voltage VGMAN may be further reduced, a ripple or a fluctuation of data voltages generated based on the gamma voltage VGMAN may be reduced, and the flicker in the low gray image of a display device including the gamma voltage generator 100a may be reduced.
Referring to
The input circuit 220a may receive the first reference voltage VREF1 and the second reference voltage VREF2, and the reference voltage select circuit 240a may select one of the first reference voltage VREF1 and the second reference voltage VREF2 by comparing the N-th gamma voltage VGMAN with the first reference voltage VREF1 that is a lower one of the first and second reference voltages VREF1 and VREF2. The input circuit 220a may provide a reference voltage selected by the reference voltage select circuit 240a among the first reference voltage VREF1 and the second reference voltage VREF2 to the DAC circuit 260, and the DAC circuit 260 may generate an analog voltage VA corresponding to a gamma code GCODEN based on the selected reference voltage.
The output circuit 280b may output the N-th gamma voltage VGMAN based on the analog voltage VA received from the DAC circuit 260. The output circuit 280b may be controlled by the gain control circuit 290a to output the analog voltage VA as the N-th gamma voltage VGMAN without applying the gain of the output circuit 280b or to generate the N-th gamma voltage VGMAN by applying the gain of the output circuit 280b to the analog voltage VA. Here, the gain of the output circuit 280b may be a ratio of the N-th gamma voltage VGMAN that is an output voltage of the output circuit 280b to the analog voltage VA that is an input voltage of the output circuit 280b. Further, when the gain of the output circuit 280b is not applied, the output circuit 280b outputs the N-th gamma voltage VGMAN substantially the same as the analog voltage VA received from the DAC circuit 260, that is, the gain of the output circuit 280b equals to 1. Further, when the gain of the output circuit 280b is applied, the output circuit 280b generates the N-th gamma voltage VGMAN by multiplying the analog voltage VA by the gain of the output circuit 280b which is different from 1. For example, in a case where the gain of the output circuit 280b is greater than 1, the N-th gamma voltage VGMAN that is the output voltage of the output circuit 280b may be higher than the analog voltage VA that is the input voltage of the output circuit 280b.
In some embodiments, as illustrated in
The gain control circuit 290a may compare the N-th gamma voltage VGMAN with the second reference voltage VREF2 that is a higher one of the first and second reference voltages VREF1 and VREF2. In some embodiments, to compare the N-th gamma voltage VGMAN with the second reference voltage VREF2, the gain control circuit 290a may receive the gamma code GCODEN corresponding to the N-th gamma voltage VGMAN. For example, the gain control circuit 290a may previously store a code value corresponding to the second reference voltage VREF2, and may compare the N-th gamma voltage VGMAN with the second reference voltage VREF2 by comparing the gamma code GCODEN with the stored code. In other embodiments, the gain control circuit 290a may receive a select value corresponding to a result of a comparison between the N-th gamma voltage VGMAN and the second reference voltage VREF2 from a controller, and may include a register for storing the select value. In this case, the gain control circuit 290a may generate the gain application signal SGA based on the select value stored in the register.
Further, the gain control circuit 290a may control the output circuit 280b such that the gain of the output circuit 280b may be selectively applied according to a result of a comparison between the N-th gamma voltage VGMAN and the second reference voltage VREF2. In some embodiments, the gain control circuit 290a may control the output circuit 280b to output the analog voltage VA as the N-th gamma voltage VGMAN without applying the gain of the output circuit 280b in a case where the N-th gamma voltage VGMAN is less than or equal to the second reference voltage VREF2, and may control the output circuit 280b to generate the N-th gamma voltage VGMAN by multiplying the analog voltage VA by the gain of the output circuit 280b in a case where the N-th gamma voltage VGMAN is greater than the second reference voltage VREF2. For example, in a case where the N-th gamma voltage VGMAN is less than or equal to the second reference voltage VREF2, the gain control circuit 290a may generate the gain application signal SGA having a first level, the gain application switch GASW may decouple the second terminal of the second resistor R2 from the power supply voltage line in response to the gain application signal SGA having the first level, and the output buffer OB may output the analog voltage VA as the N-th gamma voltage VGMAN without applying the gain of the output circuit 280b. Alternatively, in a case where the N-th gamma voltage VGMAN is greater than the second reference voltage VREF2, the gain control circuit 290a may generate the gain application signal SGA having a second level, the gain application switch GASW may couple the second terminal of the second resistor R2 to the power supply voltage line in response to the gain application signal SGA having the second level, and the output buffer OB may generate the N-th gamma voltage VGMAN by amplifying the analog voltage VA with the gain of the output circuit 280b.
Accordingly, in the gamma voltage generator 100b according to embodiments, in a case where the N-th gamma voltage VGMAN is less than or equal to the first reference voltage VREF1, the N-th gamma generation circuit 200b may not apply the gain of the output circuit 280b, and may generate the N-th gamma voltage VGMAN by using the first reference voltage VREF1. Further, in a case where the N-th gamma voltage VGMAN is greater than the first reference voltage VREF1 and less than or equal to the second reference voltage VREF2, the N-th gamma generation circuit 200b may not apply the gain of the output circuit 280b, and may generate the N-th gamma voltage VGMAN by using the second reference voltage VREF2. Further, in a case where the N-th gamma voltage VGMAN is greater than the second reference voltage VREF2, the N-th gamma generation circuit 200b may apply the gain of the output circuit 280b, and may generate the N-th gamma voltage VGMAN by using the second reference voltage VREF2. As described above, the N-th gamma generation circuit 200b may generate the N-th gamma voltage VGMAN by selectively applying the gain of the output circuit 280b and by using an optimal reference voltage among the first and second reference voltages VREF1 and VREF2. Accordingly, a ripple or a fluctuation of the N-th gamma voltage VGMAN may be reduced, a ripple or a fluctuation of data voltages generated based on the N-th gamma voltage VGMAN may be reduced, and thus a flicker of a display device including the gamma voltage generator 100b may be reduced.
Referring to
The gamma generation circuit 200b may compare a gamma voltage VGMAN with at least one of the first reference voltage VREF1 and the second reference voltage VREF2 (S320). In some embodiments, a reference voltage select circuit 240a may compare the gamma voltage VGMAN with the first reference voltage VREF1 that is a lower one of the first and second reference voltages VREF1 and VREF2, and a gain control circuit 290a may compare the gamma voltage VGMAN with the second reference voltage VREF2 that is a higher one of the first and second reference voltages VREF1 and VREF2.
In a case where the gamma voltage VGMAN is less than or equal to the first reference voltage VREF1 (S330: YES), the gamma generation circuit 200b may generate the gamma voltage VGMAN by using the first reference voltage VREF1 without applying a gain of an output circuit 280b (S340). For example, as illustrated in
Further, in a case where the gamma voltage VGMAN is greater than the first reference voltage VREF1 and less than or equal to the second reference voltage VREF2 (S330: NO and S350: YES), the gamma generation circuit 200b may generate the gamma voltage VGMAN by using the second reference voltage VREF2 without applying the gain of the output circuit 280b (S360). For example, as illustrated in
Further, in a case where the gamma voltage VGMAN is greater than the second reference voltage VREF2 (S330: NO and S350: NO), the gamma generation circuit 200b may generate the gamma voltage VGMAN by using the second reference voltage VREF2 and by applying the gain of the output circuit 280b (S370). For example, as illustrated in
As described above, in a method of generating the gamma voltage VGMAN by the gamma generation circuit 200b according to embodiments, the gain of the output circuit 280b may be selectively applied, and the gamma voltage VGMAN may be generated by using an optimal reference voltage among the first and second reference voltages VREF1 and VREF2. Accordingly, a ripple or a fluctuation of the gamma voltage VGMAN may be reduced, a ripple or a fluctuation of data voltages may be reduced, and thus a flicker of a display device may be reduced.
Referring to
The input circuit 220b may receive a first reference voltage VREF1 and a second reference voltage VREF2, and may selectively provide the first reference voltage VREF1 or the second reference voltage VREF2 to the DAC circuit 260 in response to a reference voltage control signal SRVC of the reference voltage select circuit 240a. In some embodiments, as illustrated in
Referring to
The input circuit 220c may receive first through L-th reference voltages VREF1, VREF2, . . . , VREFL, and may provide a reference voltage selected among the first through L-th reference voltages VREF1, VREF2, . . . , VREFL to the DAC circuit 260 in response to a reference voltage control signal SRVC′ of the reference voltage select circuit 240b. In some embodiments, as illustrated in
The reference voltage select circuit 240b may select one of the first through L-th reference voltages VREF1, VREF2, . . . , VREFL by comparing the gamma voltage VGMAN with the first through L-th reference voltages VREF1, VREF2, . . . , VREFL. In some embodiments, the reference voltage select circuit 240b may select a reference voltage that is higher than or equal to the gamma voltage VGMAN and is closest to the gamma voltage VGMAN among the first through L-th reference voltages VREF1, VREF2, . . . , VREFL. Accordingly, the gamma generation circuit 200d may generate the gamma voltage VGMAN by using an optimal reference voltage among first through L-th reference voltages VREF1, VREF2, . . . , VREFL.
Referring to
The gain control circuit 290b may generate a gain value adjustment signal GVAS for adjusting the value of the gain of the output circuit 280c, and a gain application signal SGA for selectively applying the gain of the output circuit 280c by comparing a gamma voltage VGMAN with a second reference voltage VREF2. The value of the gain of the output circuit 280c may be adjusted in response to the gain value adjustment signal GVAS, and the gain of the output circuit 280c may be selectively applied in response to the gain application signal SGA.
In some embodiments, as illustrated in
Referring to
Each of the first through (N−M)-th gamma generation circuits 120_1, . . . , 120_N−M may generate a gamma voltage VGMA1, . . . , VGMAN−M by using one reference voltage VREF. However, each of (N−M+1)-th through N-th gamma generation circuits 200_N−M+1, . . . , 200_N may receive two or more reference voltages VREF1_N−M+1, VREF2_N−M+1, . . . , VREF1_N and VREF2_N, and may generate a gamma voltage VGMAN−M+1, . . . , VGMAN by selectively using the two or more reference voltages VREF1_N−M+1, VREF2_N−M+1, . . . , VREF1_N and VREF2_N. For example, each of the (N−M+1)-th through N-th gamma generation circuits 200_N−M+1, . . . , 200_N may include an input circuit 220, a reference voltage select circuit 240, a DAC circuit 260 and an output circuit 280. In some embodiments, each of the (N−M+1)-th through N-th gamma generation circuits 200_N−M+1, . . . , 200_N may further include a gain control circuit 290.
As illustrated in a first graph 410 of
Referring to
The display panel 510 may include a plurality of data lines, a plurality of scan lines, and the plurality of pixels PX coupled to the plurality of data lines and the plurality of scan lines. In some embodiments, each pixel PX may include a light emitting element, and the display panel 510 may be a light emitting display panel. For example, the light emitting element may be an organic light emitting diode (OLED), and the display panel 510 may be an OLED display panel. In other embodiments, the light emitting element may be a nano light emitting diode (NED), a quantum dot (QD) light emitting diode, a micro light emitting diode, an inorganic light emitting diode, or any other suitable light emitting element. In other embodiments, each pixel PX may include a switching transistor, and a liquid crystal capacitor coupled to the switching transistor, and the display panel 510 may be a liquid crystal display (LCD) panel. However, the display panel 510 is not limited to the light emitting display panel the LCD panel, and may be any other suitable display panel.
The scan driver 520 may generate the scan signals SS based on a scan control signal SCTRL received from the controller 550, and may sequentially provide the scan signals SS to the plurality of pixels PX on a row-by-row basis through the plurality of scan lines. In some embodiments, the scan control signal SCTRL may include, but not limited to, a scan start signal and a scan clock signal. In some embodiments, the scan driver 520 may be integrated or formed in a peripheral portion of the display panel 510. In other embodiments, the scan driver 520 may be implemented with one or more integrated circuits.
The gamma voltage generator 530 may include a plurality of gamma generation circuits that respectively generate the plurality of gamma voltages VGMA corresponding to gamma codes GCODE received from the controller 550. According to embodiments, the gamma voltage generator 530 may be a gamma voltage generator 100a of
The data driver 540 may receive output image data ODAT and a data control signal DCTRL from the controller 550, may receive the plurality of gamma voltages VGMA from the gamma voltage generator 530, may generate gray voltages respectively corresponding to a plurality of gray levels (e.g., 256 gray levels from a 0-gray level to a 255-gray level) based on the plurality of gamma voltages VGMA, and may provide the gray voltages corresponding to the output image data ODAT as the data voltages DV to the plurality of pixels PX through the plurality of data lines. In some embodiments, the data control signal DCTRL may include, but not limited to, an output data enable signal, a horizontal start signal and a load signal. In some embodiments, the data driver 540 and the controller 550 may be implemented with a single integrated circuit, and the single integrated circuit may be referred to as the TED integrated circuit. In other embodiments, the data driver 540 and the controller 550 may be implemented with separate integrated circuits.
The controller 550 (e.g., a timing controller (TCON)) may receive input image data IDAT and a control signal CTRL from an external host processor (e.g., an application processor (AP), a graphics processing unit (GPU) or a graphics card). In some embodiments, the input image data IDAT may be, but not limited to, RGB image data including red image data, green image data and blue image data. The control signal CTRL may include, but not limited to, a vertical synchronization signal, a horizontal synchronization signal, an input data enable signal, a master clock signal, etc. The controller 550 may generate the output image data ODAT, the data control signal DCTRL and the scan control signal SCTRL based on the input image data IDAT and the control signal CTRL. The controller 550 may control an operation of the data driver 540 by providing the output image data ODAT and the data control signal DCTRL to the data driver 540, and may control an operation of the scan driver 520 by providing the scan control signal SCTRL to the scan driver 520.
Referring to
The processor 1110 may perform various computing functions or tasks. The processor 1110 may be an application processor (AP), a micro processor, a central processing unit (CPU), etc. The processor 1110 may be coupled to other components via an address bus, a control bus, a data bus, etc. Further, in some embodiments, the processor 1110 may be further coupled to an extended bus such as a peripheral component interconnection (PCI) bus.
The memory device 1120 may store data for operations of the electronic device 1100. For example, the memory device 1120 may include at least one non-volatile memory device such as an erasable programmable read-only memory (EPROM) device, an electrically erasable programmable read-only memory (EEPROM) device, a flash memory device, a phase change random access memory (PRAM) device, a resistance random access memory (RRAM) device, a nano floating gate memory (NFGM) device, a polymer random access memory (PoRAM) device, a magnetic random access memory (MRAM) device, a ferroelectric random access memory (FRAM) device, etc, and/or at least one volatile memory device such as a dynamic random access memory (DRAM) device, a static random access memory (SRAM) device, a mobile dynamic random access memory (mobile DRAM) device, etc.
The storage device 1130 may be a solid state drive (SSD) device, a hard disk drive (HDD) device, a CD-ROM device, etc. The I/O device 1140 may be an input device such as a keyboard, a keypad, a mouse, a touch screen, etc, and an output device such as a printer, a speaker, etc. The power supply 1150 may supply power for operations of the electronic device 1100. The display device 1160 may be coupled to other components through the buses or other communication links.
In the display device 1160, at least one gamma generation circuit may receive a plurality of reference voltages, and may generate a gamma voltage by using an optimal reference voltage among the plurality of reference voltages. Accordingly, a ripple or a fluctuation of the gamma voltage may be reduced, a ripple or a fluctuation of data voltages generated based on the gamma voltage may be reduced, and thus a flicker of the display device 1160 may be reduced.
The inventive concepts may be applied to any display device 1160, and any electronic device 1100 including the display device 1160. For example, the inventive concepts may be applied to a mobile phone, a smart phone, a tablet computer, a wearable electronic device, a virtual reality (VR) device, a television (TV), a digital TV, a 3D TV, a personal computer (PC), a home appliance, a laptop computer, a personal digital assistant (PDA), a portable multimedia player (PMP), a digital camera, a music player, a portable game console, a navigation device, etc.
The foregoing is illustrative of embodiments and is not to be construed as limiting thereof. Although a few embodiments have been described, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from the novel teachings and advantages of the present inventive concept. Accordingly, all such modifications are intended to be included within the scope of the present inventive concept as defined in the claims. Therefore, it is to be understood that the foregoing is illustrative of various embodiments and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2022-0057807 | May 2022 | KR | national |
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| 20230368719 A1 | Nov 2023 | US |
