# US 12,112,693 B1 · Display device with display panel and controller for display panel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,112,693 B1 - Document ID: US12112693B1 - Status: Granted - Kind: B1 - Application number: 18/224,374 - Filed: 2023-07-20 - Granted: 2024-10-08 - Earliest claimed: 2022-07-28 - Assignees: LG Display Co., Ltd. - Applicants: LG Display Co., Ltd. - Inventors: Wookyu Sang; Moonsoo Chung - Web page: https://patentgrep.com/patent/US12112693B1 ## CPC - G09G 3/32: semiconductive, e.g. using light-emitting diodes [LED] - G09G 3/3233: with pixel circuitry controlling the current through the light-emitting element - G09G 3/3266: Details of drivers for scan electrodes - G09G 2310/0267: Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays - G09G 2320/0233: Improving the luminance or brightness uniformity across the screen - G09G 2320/0247: Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes - G09G 2320/0271: Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) ## Abstract A display device according to the embodiment of the present disclosure includes: a display panel that includes a display area where a plurality of pixels is disposed and a non-display area disposed around the display area; a gate driver that provides a scan signal and an emission control signal to the display panel; and a controller that drives the display panel in accordance with a refresh rate. The plurality of pixels includes a light emitting element and a pixel circuit that drives the light emitting element. The pixel circuit is driven in sets including at least one refresh period and at least one hold period in low frequency driving. The controller controls dynamically the refresh rate during the at least one set when a gradation of an image changes, and simultaneously, changes and supplies a bias voltage during the at least one hold period. ## Claims ### Claim 1 A display device, comprising: a display panel that comprises a display area where a plurality of pixels is disposed; and a controller configured to drive the display panel in accordance with a refresh rate, wherein the plurality of pixels comprises a light emitting element and a pixel circuit configured to drive the light emitting element, wherein the pixel circuit is configured to be driven in sets including at least one refresh period and at least one hold period, wherein the controller is configured to change a bias voltage during the at least one hold period in at least one set when a gradation of an image changes, wherein the at least one set comprises a plurality of subsets, wherein the bias voltage is at a first voltage level during a first hold period of the plurality of subsets, wherein the bias voltage is at a second voltage level during a second hold period of the plurality of subsets, and wherein the second voltage level is different from the first voltage level. ### Claim 2 (depends on 1) The display device of claim 1, wherein, the controller is configured to simultaneously control dynamically the refresh rate during the at least one set. ### Claim 3 (depends on 2) The display device of claim 2, wherein, the display panel is configured to be driven at a first refresh rate before the at least one set and is configured to be driven at a second refresh rate during the at least one set when the gradation of the image changes. ### Claim 4 (depends on 3) The display device of claim 3, wherein the first refresh rate is lower than 50 Hz. ### Claim 5 (depends on 3) The display device of claim 3, wherein the second refresh rate is higher than the first refresh rate and lower than 50 Hz. ### Claim 6 (depends on 1) The display device of claim 1, wherein each of the plurality of subsets includes at least one refresh period and at least one hold period. ### Claim 7 (depends on 1) The display device of claim 1, wherein the display panel is configured to be driven at a first refresh rate in the at least one set and is configured to be driven at one or more second refresh rates in the plurality of subsets. ### Claim 8 (depends on 7) The display device of claim 7, wherein a combination of the one or more second refresh rates of the plurality of subsets is the first refresh rate. ### Claim 9 (depends on 1) The display device of claim 1, wherein the bias voltage has different voltage levels during hold periods of the plurality of subsets. ### Claim 10 (depends on 9) The display device of claim 9, wherein the different voltage levels of the bias voltage during the hold periods of the plurality of subsets are to increase in stages to a voltage level of the bias voltage during refresh periods of the plurality of subsets. ### Claim 11 (depends on 9) The display device of claim 9, wherein the bias voltage has a same voltage level during refresh periods of the plurality of subsets. ### Claim 12 (depends on 9) The display device of claim 9, wherein the display panel is configured to be driven at different refresh rates in the plurality of subsets. ### Claim 13 (depends on 12) The display device of claim 12, wherein the different refresh rates are to decrease sequentially in the plurality of subsets. ### Claim 14 (depends on 1) The display device of claim 1, wherein the bias voltage has a same voltage level during the plurality of subsets. ### Claim 15 (depends on 14) The display device of claim 14, wherein the display panel is configured to be driven at different refresh rates in the plurality of subsets. ### Claim 16 (depends on 1) The display device of claim 1, wherein a first frame after the gradation change of the image comprises a plurality of refresh periods. ### Claim 17 (depends on 1) The display device of claim 1, wherein the pixel circuit comprises: a driving transistor of which a first electrode is configured to receive a data voltage and the bias voltage and a second electrode is connected to the light emitting element; a switching transistor that is connected between the driving transistor and a data line and is configured to apply the data voltage to the driving transistor in response to a first scan signal; and a bias transistor that is configured to apply the bias voltage to the driving transistor in response to a second scan signal. ### Claim 18 (depends on 1) The display device of claim 1, further comprising a gate driver that is configured to provide a scan signal to the display panel; wherein the gate driver comprises a first to a fourth scan drivers that are configured to apply a first to a fourth scan signals to the pixel circuit and an emission control signal driver that is configured to apply an emission control signal, and wherein the second scan driver comprises a second odd-numbered scan driver and a second even-numbered scan driver. ### Claim 19 (depends on 1) The display device of claim 1, further comprising a gate driver that is configured to provide a scan signal and an emission control signal to the display panel; wherein the display panel further comprises: a bias voltage bus line that is configured to apply the bias voltage to the pixel circuit; and an initialization voltage bus line that is configured to apply an initialization voltage to the pixel circuit, and wherein the bias voltage bus line and the initialization voltage bus line are disposed between the gate driver and the display area. ### Claim 20 (depends on 1) The display device of claim 1, wherein the display area comprises one or more optical areas having a light-transmission structure formed therein and general areas other than the one or more optical areas. ### Claim 21 (depends on 20) The display device of claim 20, wherein the one or more optical areas overlap optical electronics. ### Claim 22 (depends on 20) The display device of claim 20, wherein a resolution of the one or more optical areas is lower than a resolution of the general areas. ### Claim 23 (depends on 1) The display device of claim 1, wherein the bias voltage is to increase in stages during hold periods of a plurality of sets immediately after the gradation of the image changes. ### Claim 24 (depends on 23) The display device of claim 23, wherein in each of the plurality of set, the bias voltage has a same voltage level in each of the plurality of subsets. ### Claim 25 (depends on 23) The display device of claim 23, wherein refresh rates in the plurality of sets are to decrease sequentially. ### Claim 26 (depends on 1) The display device of claim 1, wherein the pixel circuit comprises a driving transistor of which a first electrode is configured to receive a data voltage and the bias voltage and a second electrode is connected to the light emitting element, and wherein the bias voltage is to be applied to the first electrode of the driving transistor before a sampling period in which a threshold voltage of the driving transistor is sampled in the at least one refresh period and is to be applied to the first electrode of the driving transistor before a light emission period in the at least one hold period. ### Claim 27 (depends on 26) The display device of claim 26, wherein the bias voltage is higher than the data voltage. ### Claim 28 (depends on 1) The display device of claim 1, wherein during the at least one set, the bias voltage of the at least one hold period is set to be 2 V lower than the bias voltage of the at least one refresh period. ### Claim 29 A display device, comprising: a display panel including a plurality of pixels; and a controller configured to control driving of the display panel in accordance with a refresh rate, wherein the display panel is configured to be driven in sets including at least one refresh period and at least one hold period, wherein at least one set of the sets, after a gradation change of an image, comprises a plurality of subsets including a first subset and a second subset, wherein the display device is configured to be driven at a first subset refresh rate in the first subset, wherein the display device is configured to be driven at a second subset refresh rate in the second subset, and wherein the second subset refresh rate is different from the first subset refresh rate. ### Claim 30 (depends on 29) The display device of claim 29, wherein in a first set after the gradation change of the image, the controller is configured to drive the display panel such that a plurality of refresh periods is included, and wherein the controller is configured to control dynamically the refresh rate during the at least one set after the gradation change of the image including the first set, and simultaneously, change and supply a bias voltage during the at least one hold period in the at least one set. ### Claim 31 (depends on 30) The display device of claim 30, wherein the display device is configured to be driven at a first refresh rate in the at least one set and is configured to be driven at one or more second refresh rates higher than the first refresh rate in the plurality of subsets, and wherein a combination of the one or more second refresh rates is the first refresh rate. ### Claim 32 A display device, comprising: a display panel comprising a display area where a plurality of pixels is disposed; and a controller configured to drive the display panel in accordance with a refresh rate, wherein the plurality of pixels comprises a light emitting element and a pixel circuit configured to drive the light emitting element, wherein the pixel circuit is configured to be driven in sets including at least one refresh period and at least one hold period, wherein the controller is configured to change a bias voltage during the at least one hold period in at least one set when a gradation of an image changes, wherein the at least one set comprises a plurality of subsets, wherein the display panel is configured to be driven at different refresh rates in the plurality of subsets, and wherein the different refresh rates are to decrease sequentially in the plurality of subsets. ### Claim 33 A display device, comprising: a display panel comprising a display area where a plurality of pixels is disposed; and a controller configured to drive the display panel in accordance with a refresh rate, wherein the plurality of pixels comprises a light emitting element and a pixel circuit configured to drive the light emitting element, wherein the pixel circuit is configured to be driven in sets including at least one refresh period and at least one hold period, wherein the controller is configured to change a bias voltage during the at least one hold period in at least one set when a gradation of an image changes, wherein the pixel circuit comprises a driving transistor, wherein a first electrode of the driving transistor is configured to receive a data voltage and the bias voltage, and a second electrode of the driving transistor is connected to the light emitting element, and wherein the bias voltage to be applied to the first electrode during a bias section period is higher than the data voltage.