Display device

Abstract

The display device includes: a plurality of pixel circuits each having a switching element that switches between light emission and non-light emission of a self-light-emitting element, and disposed corresponding to each of a plurality of pixels; and a control circuit that controls the plurality of pixel circuits based on an image signal of an image to be displayed, and controls the switching element to cause the self-light-emitting element to emit light at least for a constant period from the start of a dimming control period and a constant period until the end of the dimming control period, when a longest period among a plurality of periods during which the self-light-emitting element continuously does not emit light in one frame period among a plurality of frame periods that constitute the image is set as a black insertion period, and a remaining period other than the black insertion period in the one frame period is set as the dimming control period.

Description

Technical Field

[0001] This invention relates to a display device. Background Technology

[0002] Patent Document 1 discloses a display device that allows current to flow through an EL element only during 1 / N of a frame, and does not allow current to flow during other periods, while applying a reverse bias voltage to the EL element. Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2008-146093 Summary of the Invention The technical problem to be solved by the present invention

[0004] However, the aforementioned patent document 1 did not adequately study the configuration for suppressing motion blur in images while obtaining the necessary brightness.

[0005] The purpose of this invention is to provide a display device that can suppress motion blur in images while obtaining the necessary brightness. Solution for solving the problem

[0006] One aspect of this disclosure relates to a display device, comprising: a plurality of pixel circuits having switching elements for switching between emitting and non-emitting light from a self-emissive element and the self-emissive element, and respectively disposed corresponding to a plurality of pixels; and a control circuit that, based on an image signal of a displayed image, controls the plurality of pixel circuits to switch between emitting and non-emitting light from the switching elements during one frame of a plurality of frame periods constituting the image, wherein the longest of a plurality of periods during which the self-emissive element is continuously non-emitting light is designated as a black insertion period, and the remaining periods of the one frame period excluding the black insertion period are designated as dimming control periods, the control circuit controls the switching elements to switch between emitting and non-emitting light to such that the self-emissive element emits light for at least a constant period from the beginning of the dimming control period and a constant period until the end of the dimming control period. Attached Figure Description

[0007] Figure 1 This is a block diagram schematically illustrating the main components of a display device according to an embodiment of the present disclosure. Figure 2 This is a circuit diagram illustrating an example of the configuration of a pixel circuit in a display device according to an embodiment of the present disclosure. Figure 3 This is a diagram illustrating an example of a black insertion period and a dimming control period set during one frame for a pixel displayed in a display device according to an embodiment of the present disclosure. Figure 4 This is a diagram illustrating an example of a black insertion period and dimming control period set during one frame for a pixel displayed in a display device according to a first variation of an embodiment of the present disclosure. Figure 5 This is a diagram illustrating an example of the black insertion period and dimming control period set during one frame for a pixel displayed by a display device according to a second variation of the embodiments of the present disclosure. Figure 6 This is a diagram illustrating an example of the black insertion period and dimming control period set during one frame for a pixel displayed by a display device according to a third variation of the embodiments of the present disclosure. Figure 7 This is a graph showing the correspondence between the black insertion rate, relative dimming rate, and pulse number set for a pixel displayed in a display device according to a third variation of the embodiments disclosed herein, during one frame period. Detailed Implementation

[0008] Hereinafter, embodiments and variations of the present disclosure will be described with reference to the accompanying drawings. Furthermore, in all the following drawings, the same or equivalent parts will be given the same reference numerals, and repeated descriptions will be omitted. Additionally, the embodiments and variations described below are merely examples of the present disclosure, and the present disclosure is not limited to these embodiments and variations. Even outside of these embodiments and variations, various changes can be made according to design, etc., as long as they do not depart from the technical concept of the present disclosure.

[0009] (Display device) Reference Figure 1 The following describes the display device 100 involved in the implementation method. Figure 1 This is a block diagram schematically illustrating the main components of a display device 100 according to an embodiment of the present disclosure.

[0010] Display device 100 is a display device such as an organic EL display or a quantum dot light-emitting diode (QLED) display that includes a self-emissive light-emitting element. Hereinafter, display device 100 will be described as having an organic EL element 21 (see below). Figure 2 The case of an organic EL display, which serves as the light-emitting element, will be used as an example for explanation.

[0011] like Figure 1 As shown, the display device 100 is configured to include a display unit 10, an OLED display panel 2 including a gate driving circuit 11 and an EMI control circuit 12, a source driving circuit 13, a power supply circuit 14, and a signal processing circuit 15. In the OLED display panel 2, the gate driving circuit 11 and the EMI control circuit 12 can be monolithically integrated.

[0012] In the display device 100, when an image signal of an image to be displayed is input from an external source, the signal processing circuit 15 performs various signal processing based on the image signal. Then, image information is added to the display unit 10 via an external driving circuit including a gate driving circuit 11, an EMI control circuit 12, a source driving circuit 13, and a power supply circuit 14, causing the image to be displayed. Furthermore, this external driving circuit corresponds to the control circuit of this disclosure.

[0013] That is, multiple data lines DL and multiple gate lines GL are arranged in a crisscrossing manner on the display unit 10. At each intersection of the multiple data lines DL and the multiple gate lines GL, a pixel circuit 20 for driving and displaying each pixel is connected (see below). Figure 2 Furthermore, the display unit 10 as a whole constitutes an array of multiple pixel circuits 20. In addition, multiple EMI lines EL are connected to the pixel circuits 20 of each pixel.

[0014] The power supply circuit 14 in the display unit 10 includes a first power supply ELVDD that applies a high-level power supply voltage as a constant voltage and a second power supply ELVSS that applies a low-level power supply voltage (see below). Figure 2 ).

[0015] The source drive circuit 13 supplies data signals representing image information to the display unit 10. That is, when a drive control signal is received from the signal processing circuit 15, the source drive circuit 13 supplies data signals to all data lines DL disposed on the display unit 10 based on the drive control signal. Furthermore, the drive control signal includes, for example, a clock signal used to synchronize the operation of the source drive circuit 13 with other external drive circuits.

[0016] The gate driving circuit 11 supplies a scan signal to the display unit 10 via gate lines GL. That is, when a scan control signal is received from the signal processing circuit 15, the gate driving circuit 11, based on the scan control signal, sequentially supplies an active scan signal to the display unit 10 via each of the multiple gate lines GL disposed on the display unit 10. When an active scan signal is supplied in this manner, the gate line GL changes from a non-selected state to a selected state. Furthermore, the scan control signal includes, for example, a clock signal used to synchronize the operation of the gate driving circuit 11 with other external driving circuits.

[0017] The EMI control circuit 12 applies an EMI signal to the display unit 10 to control the switching of the organic EL element 21 in the pixel circuit 20 between emitting and not emitting light. Specifically, when it receives an EMI control signal from the signal processing circuit 15, the EMI control circuit 12, based on the EMI control signal, sequentially inputs EMI signals as binarized signals representing the on and off states of the third transistor T3 (switching element), as described later, to the multiple EMI lines EL disposed on the display unit 10. In the pixel circuit 20, according to the EMI signal, the third transistor T3 becomes on, allowing the drive current supplied to the organic EL element 21 to flow, or the third transistor T3 becomes off, blocking the drive current, thereby switching the organic EL element 21 between emitting and not emitting light.

[0018] The signal processing circuit 15 includes an input image analysis unit 50, a black insertion rate / dimming rate determination unit 51, and a control signal generation unit 52. Furthermore, the black insertion rate / dimming rate determination unit 51 corresponds to the black insertion rate determination unit and dimming rate determination unit of this disclosure.

[0019] The input image analysis unit 50 analyzes the image signal and sends the analysis results to the black insertion rate / dimming rate determination unit 51. More specifically, when the signal processing circuit 15 receives the image signal, the input image analysis unit 50 detects motion vectors based on the image signal. Then, the input image analysis unit 50 calculates the average value of motion vectors over a constant period of one frame or more to determine the amount of motion in the displayed image. The input image analysis unit 50 sends the determined amount of motion to the black insertion rate / dimming rate determination unit 51.

[0020] Additionally, the input image analysis unit 50 calculates the average picture level (APL) of the displayed image based on the image signal. Then, the input image analysis unit 50 sends the calculated APL to the black insertion rate / dimming rate determination unit 51.

[0021] The black insertion rate / dimming rate determination unit 51 determines the black insertion rate and dimming rate based on the analysis results of the image signal by the input image analysis unit 50. That is, the black insertion rate / dimming rate determination unit 51 determines the black insertion rate based on the amount of motion received from the input image analysis unit 50. The black insertion rate / dimming rate determination unit 51 is set such that the greater the amount of motion input from the input image analysis unit 50, the greater the black insertion rate. In this way, since the black insertion rate / dimming rate determination unit 51 can determine the black insertion rate based on the amount of motion, it is possible to set a black insertion rate corresponding to the amount of motion of the displayed image, thereby appropriately suppressing motion blur.

[0022] Furthermore, the black insertion rate refers to the proportion of the period during which the organic EL element 21 does not emit light within one frame of the multiple frame periods constituting the image, i.e., the black insertion period. More precisely, the black insertion period is the longest of the multiple periods during which the organic EL element 21 emits light discontinuously within one frame.

[0023] The display device 100 is configured to include a black insertion period within one frame to shorten the hold time of light emitted from the display unit 10. In this way, by including a black insertion period within one frame, the display device 100 can suppress motion blur in the image.

[0024] Although details will be described later, in the display device 100, within one frame period, there are periods during which the organic EL element 21 does not emit light in order to suppress the occurrence of motion blur as described above, and periods during which the organic EL element 21 emits light intermittently in order to adjust the brightness of the light emitted from the display unit 10. Therefore, in the display device 100, the longest period of the periods during which the organic EL element 21 emits light intermittently is defined as the black insertion period. On the other hand, within one frame period, the remaining periods other than the black insertion period are defined as dimming control periods.

[0025] Furthermore, the black insertion rate / dimming rate determination unit 51 determines the dimming rate based on the APL input from the input image analysis unit 50. The dimming rate refers to the proportion of the time during which light is emitted from the display unit 10 during dimming control. Generally, organic EL displays cannot display large areas of bright images, and compared to an ideally displayed image based on the image signal, the image displayed on the display unit 10 may appear darker. Therefore, when the APL of the displayed image is high, the black insertion rate / dimming rate determination unit 51 determines the dimming rate to be greater than the initial setting value. Additionally, when the APL of the displayed image is high, and an IR drop occurs in the power supply wiring, causing a decrease in the average brightness of the image displayed on the display unit 10, the black insertion rate / dimming rate determination unit 51 determines the dimming rate to be greater than the initial setting value to compensate for the decrease in average brightness. Furthermore, the initial setting value here refers to a value preset at the factory of the display device 100, etc., and is appropriately set according to the relationship between the display performance of the display unit 10 and the image signal.

[0026] The black insertion rate / dimming rate determination unit 51 determines the configuration of the black insertion rate and dimming rate based on the analysis results of the image signal by the input image analysis unit 50 as described above. However, the black insertion rate / dimming rate determination unit 51 may also determine the configuration of the black insertion rate and dimming rate based on user settings or the content information of the displayed image.

[0027] For example, the black insertion rate / dimming rate determination unit 51 determines the black insertion rate as follows: when the displayed video is a moving image with little motion, the black insertion rate is made smaller than the initial setting value; when the video is a moving image with a lot of motion, the black insertion rate is made larger than the initial setting value.

[0028] For example, the black insertion rate / dimming rate determination unit 51 determines the black insertion rate to be lower than the initial setting value when the displayed image is a moving image with little motion, based on content information corresponding to the displayed image. On the other hand, it determines the black insertion rate to be higher than the initial setting value when the displayed image is a moving image with much motion. In this way, the black insertion rate / dimming rate determination unit 51 can appropriately determine the black insertion rate according to the type of displayed image.

[0029] Furthermore, for example, the black insertion rate / dimming rate determination unit 51 determines the dimming rate to be higher than the initial setting value when the displayed image is bright, based on content information corresponding to the displayed image. On the other hand, it determines the dimming rate to be lower than the initial setting value when the displayed image is dim.

[0030] Furthermore, the display device 100 includes an input unit 4 that receives input information from the user. Also, the black insertion rate / dimming rate determination unit 51 can determine the dimming rate configuration based on the dimming rate setting value input via the input unit 4. Thus, when the black insertion rate / dimming rate determination unit 51 determines the dimming rate configuration based on the dimming rate input via the input unit 4, the dimming rate can be controlled according to the user's preferences.

[0031] Alternatively, the black insertion rate / dimming rate determination unit 51 can also determine the configuration of the black insertion rate based on the black insertion rate setting value input via the input unit 4. In this way, when the black insertion rate / dimming rate determination unit 51 determines the configuration of the black insertion rate based on the black insertion rate input via the input unit 4, the black insertion rate can be controlled according to the user's preferences.

[0032] Alternatively, an illuminance sensor 3, communicatively connected to the signal processing circuit 15, may be provided inside or outside the display device 100. The black insertion rate / dimming rate determination unit 51 determines the dimming rate based on the measured value of the brightness around the display device 100 measured by the illuminance sensor 3.

[0033] For example, if the value representing the brightness around the display device 100 in a normal usage environment is used as a reference value, and the measured value by the illuminance sensor 3 becomes brighter than the reference value, the black insertion rate / dimming rate determination unit 51 decides to increase the dimming rate so that the displayed image does not become difficult to see due to the ambient brightness. On the other hand, if the brightness detected by the illuminance sensor 3 is darker than the reference value, the black insertion rate / dimming rate determination unit 51 decides to decrease the dimming rate to suppress the brightness of the displayed image from reaching the necessary level.

[0034] When the black insertion rate / dimming rate determination unit 51 determines the black insertion rate and the dimming rate, it inputs a signal representing the determined black insertion rate and dimming rate to the control signal generation unit 52 and to the power supply circuit 14.

[0035] For example, if the black insertion rate / dimming rate determination unit 51 determines that the black insertion rate is greater than the initial setting value, the brightness of the light emitted from the display unit 10 will decrease because the light emission period of the organic EL element 21 becomes shorter.

[0036] Therefore, when the black insertion rate is greater than the initial set value, the control signal generation unit 52 sends a drive control signal to the source drive circuit 13 to perform grayscale correction to compensate for the reduction in brightness.

[0037] In addition, when the black insertion rate is greater than the initial setting value, the power supply circuit 14 adjusts the voltage applied to the display unit 10 to compensate for the decrease in brightness.

[0038] Additionally, the black insertion rate / dimming rate determination unit 51 inputs signals indicating the determined black insertion rate and dimming rate to the EMI control circuit 12. Based on the input signals, the EMI control circuit 12 generates EMI signals that define the number of times the organic EL element 21 emits light, the light emission timing, and the light emission period within one frame, and inputs them to the display unit 10 via the EMI line EL.

[0039] Furthermore, in the display device 100, the black insertion rate is set to be fixed in each of the multiple frames constituting the image displayed by the display unit 10. This is because if the black insertion rate is different in each frame period, and the brightness is different in each frame period, flickering will occur in the displayed image.

[0040] (Pixel circuit) Next, refer to Figure 2 This describes the pixel circuit 20 configured for each pixel. Figure 2This is a circuit diagram illustrating an example of the configuration of a pixel circuit 20 in a display device 100 according to an embodiment of the present disclosure. The pixel circuit 20 described is exemplified by one located at the intersection of the m-th data line DL(m) of the plurality of data lines DL disposed on the display unit 10 and the n-th gate line GL(n) of the plurality of gate lines GL. Furthermore, each pixel circuit 20 is connected to a p-th EML line (p). Additionally, m, n, and p are natural numbers.

[0041] like Figure 2 As shown, the pixel circuit 20 includes a first transistor T1, a second transistor T2 and a third transistor T3, a capacitor C1 and an organic EL element 21.

[0042] The first transistor T1 is a thin-film transistor for scanning, electrically connected to the gate line GL(n) on the gate side. The second transistor T2 is a thin-film transistor for driving. The third transistor T3 is a switching element that allows or blocks the drive current supplied to the organic EL element 21. The state in which drive current flows through the third transistor T3 is called the on state, and the state in which drive current is blocked is called the off state. Furthermore, the control of switching between the on and off states via the third transistor T3 is called on / off control.

[0043] The display unit 10 uses an active matrix driving method that drives the organic EL element 21 by using thin-film transistors fabricated within the pixels.

[0044] More specifically, such as Figure 2 As shown, a second transistor T2 and a third transistor T3 are connected in series from the first power supply ELVDD toward the organic EL element 21. Furthermore, one end of a capacitor C1 is connected between the first power supply ELVDD and the source of the second transistor T2, and the drain of the second transistor T2 is connected to the source of the third transistor T3.

[0045] The drain of the third transistor T3 is connected to the anode of the organic EL element 21, and the gate of the third transistor T3 is connected to the EMI line EL(p).

[0046] The gate of the first transistor T1 is connected to the gate line GL(n). The source of the first transistor T1 is connected to the data line DL(m). The drain of the first transistor T1 is connected to the other end of the capacitor C1.

[0047] When the gate line GL(n) is in the non-selected state, the first transistor T1 is in the off state. When the gate line GL(n) is changed from the non-selected state to the selected state by supplying an active scan signal, the first transistor T1 is turned on, and the source and drain of the first transistor T1 are connected.

[0048] Therefore, a data signal is supplied to capacitor C1 via data line DL(m), and a voltage corresponding to the data signal is maintained in capacitor C1. Subsequently, when gate line GL(n) changes from a selected state to a non-selected state, the first transistor T1 is turned off, determining the voltage maintained in capacitor C1. Then, the second transistor T2 supplies drive current to organic EL element 21 based on the voltage maintained in capacitor C1.

[0049] The drive current supplied from the second transistor T2 to the organic EL element 21 is controlled by the third transistor T3 for on / off switching. That is, an EMI signal is input from the EMI control circuit 12 to the third transistor T3 through the EMI line EL(p). Therefore, the third transistor T3 is configured to be in the on state and the off state based on the EMI signal.

[0050] During the period when the third transistor T3 is in the on state, its source-drain junction is conducting, supplying drive current to the organic EL element 21, causing the organic EL element 21 to emit light. Conversely, during the period when the third transistor T3 is in the off state, the drive current is blocked, and the organic EL element 21 does not emit light. Thus, by switching the third transistor T3 between the on and off states, it is possible to switch the organic EL element 21 from emitting light to not emitting light.

[0051] In the display device 1, the amount of light emitted by the organic EL element 21 is controlled by switching the on / off state of the third transistor T3.

[0052] (Dimming control) Below, refer to Figure 3 Explain the dimming control in the display device 100. Figure 3 This diagram illustrates an example of a black insertion period Ta and a dimming control period Tb set within a one-frame period Tf for a pixel displayed in a display device 100 according to an embodiment of this disclosure. Figure 3 The diagram illustrates the cases where the dimming rate is 100%, 75%, 50%, and 25%, allowing for a comparison between the black insertion period Ta and the dimming control period Tb.

[0053] exist Figure 3 In the diagram, the horizontal axis represents time, and the vertical axis represents the amount of positive drive current IF flowing through the organic EL element 21. During periods when the drive current IF is high, the organic EL element 21 emits light; during periods when the drive current IF is not flowing, it does not emit light.

[0054] In addition, Figure 3The diagram shows the case where half of the period in a frame Tf is the black insertion period Ta (Ta = 0.5 × Tf), that is, the black insertion rate is 50%, but the proportion of the black insertion period Ta in a frame Tf is not limited to this.

[0055] In the display device 100 of this embodiment, in order to suppress motion blur in the image to be displayed, a black insertion period Ta is set within a 1-frame period Tf. Furthermore, since the black insertion period Ta and the dimming control period Tb are set separately within a 1-frame period Tf, the black insertion rate and dimming rate within a 1-frame period can be set independently.

[0056] In this way, since the black insertion rate and dimming rate can be set independently, the brightness of the displayed image can be changed without complex controls such as changing the grayscale voltage, while keeping the black insertion period fixed at a constant period.

[0057] Furthermore, if the proportion of the black insertion period Ta in the 1-frame period Tf increases, and the period during which the organic EL element 21 emits light is too short, flickering may sometimes occur. Additionally, the shorter the dimming control period Tb, the greater the brightness of the light emitted from the organic EL element 21 needs to be within that period. Therefore, it is necessary to increase the amount of the driving current IF flowing through the organic EL element 21 in the pixel circuit 20.

[0058] Therefore, considering the frame rate of the image to be displayed and the screen size in the OLED display panel 2, the black insertion rate is preferably a value in the range of 25% or more and 50% or less.

[0059] In the display device 100 of this embodiment, since the black insertion rate is 50% during 1 frame period Tf, the dimming control period Tb during 1 frame period Tf is also changed to half of the 1 frame period Tf (Tb = (1-0.5)×Tf). During 1 frame period Tf, the black insertion period Ta is set to the latter part of the dimming control period Tb.

[0060] like Figure 3 As shown, in the display device 100, the organic EL element 21 is configured to emit light for at least a constant period from the start of the dimming control period Tb and a constant period until the end of the dimming control period Tb, by controlling the on / off state of the third transistor T3 based on the EMI signal input from the EMI control circuit 12. Furthermore, in the display device 100, while keeping the length of the dimming control period Tb fixed, the dimming rate is changed to 75%, 50%, or 25% during the dimming control period Tb by varying the length of a single emission period of the organic EL element 21.

[0061] In this way, by ensuring that the organic EL element 21 emits light during a constant period from the beginning to the end of the dimming control period Tb, the display device 100 can maintain a constant length for the dimming control period Tb within one frame period Tf. Furthermore, since the length of the dimming control period Tb can be constant within one frame period Tf, the length of the black insertion period Ta can also be fixed within a constant period. Therefore, regardless of the brightness of the displayed image, the effect of motion blur suppression in the image can be maintained constant.

[0062] Specifically, when the dimming rate is set to 75%, 75% of the dimming control period Tb becomes the emission period. Furthermore, within the dimming control period Tb, the lengths of the emission periods are all the same. That is, the length of a single emission period of the organic EL element 21 becomes (1 / 2) × 0.75 × the dimming control period Tb.

[0063] Similarly, when the dimming rate is set to 50%, the length of the single emission period of the organic EL element 21 is (1 / 2) × 0.50 × dimming control period Tb, and when the dimming rate is set to 25%, the length of the single emission period of the organic EL element 21 is (1 / 2) × 0.25 × dimming control period Tb.

[0064] Furthermore, for each of the multiple frame periods constituting the image, regardless of the dimming rate set in the dimming control period Tb, the end timing of the last emission period in the dimming control period Tb is set to be consistent with each other. In this way, for each of the multiple frame periods, since the end timing of the last emission period is consistent with each other, the black insertion period Ta set at the end of the dimming control period Tb can be kept constant in each of the multiple frame periods.

[0065] In this way, regardless of the dimming rate set in Tb during dimming control, the black insertion period Ta can be kept constant in each of the multiple frame periods, thus ensuring a constant suppression effect on motion blur in the displayed image.

[0066] Furthermore, in this embodiment, the two emission periods in the dimming control period Tb are of the same length. While the two emission periods do not necessarily need to be the same length, if the lengths of the emission periods in the dimming control period Tb are different, it is easily detected as flickering; therefore, it is preferable that the two periods are of the same length.

[0067] In addition, grayscale corrections such as gamma correction can also apply the correction value set when the dimming rate is 100% to other dimming rates.

[0068] (First variation) Next, refer to Figure 4The dimming control in the display device 100 according to the first variation of this embodiment will be described. Figure 4 This diagram illustrates an example of a black insertion period Ta and a dimming control period Tb set within a frame period Tf for a pixel displayed in a display device 100 according to a first variation of an embodiment of this disclosure. Figure 4 The diagram illustrates the cases where the dimming rate is 100%, 75%, 50%, and 25%, allowing for a comparison between the black insertion period Ta and the dimming control period Tb. Figure 4 In the diagram, the horizontal axis represents time, and the vertical axis represents the amount of positive drive current IF flowing through the organic EL element 21.

[0069] The first variation of this embodiment relates to a display device 100 that has the same configuration as the display device 100 of this embodiment. Therefore, the same reference numerals are used to mark the same parts and their descriptions are omitted.

[0070] In the display device 100 of this embodiment, the black insertion rate of Tf during one frame is 50%, while in the display device 100 of the first variation of this embodiment, the black insertion rate of Tf during one frame is 35%.

[0071] Furthermore, in the display device 100 of this embodiment, the organic EL element 21 emits light twice during the dimming control period Tb of one frame Tf. In contrast, in the display device 100 of the first variant of this embodiment, the difference is that the number of times the organic EL element 21 emits light is increased to four. Hereinafter, the number of times the organic EL element 21 emits light will be referred to as the pulse number.

[0072] In other words, since the dimming control period Tb of the display device 100 according to the first modification of this embodiment is longer than that of the display device 100 according to this embodiment, the number of pulses is increased to prevent the period of discontinuous light emission of the organic EL element 21 during the dimming control period Tb from becoming longer. In this way, by increasing the number of pulses during the dimming control period Tb, the dimming control period Tb and the black insertion period Ta can be clearly distinguished.

[0073] Furthermore, even when the dimming rate is reduced, from the viewpoint of distinguishing between the dimming control period Tb and the black insertion period Ta, it is preferable to increase the number of pulses in the dimming control period Tb.

[0074] exist Figure 4The diagram illustrates the dimming control period Tb in the display device 100 according to the first variation of this embodiment, when the black insertion rate is 35% during a frame period Tf, and the dimming rate is 75%, 50%, and 25%. The number of pulses in the dimming control period Tb is 4.

[0075] With the dimming rate set to 75%, 75% of the dimming control period Tb becomes the emission period. Furthermore, within the dimming control period Tb, the lengths of the emission periods are all the same. That is, the length of a single emission period of the organic EL element 21 becomes (1 / 4) × 0.75 × the dimming control period Tb.

[0076] Similarly, when the dimming rate is set to 50%, the length of the single emission period of the organic EL element 21 is (1 / 4) × 0.50 × dimming control period Tb, and when the dimming rate is set to 25%, the length of the single emission period of the organic EL element 21 is (1 / 4) × 0.25 × dimming control period Tb.

[0077] Furthermore, the lengths of Tb during dimming control and during the non-emitting period are also the same. That is to say, as... Figure 4 As shown, in the display device 100 of the first variation of this embodiment, when the number of pulses in the dimming control period Tb is set to a, a = 4. On the other hand, there are 3 non-light-emitting periods between the light-emitting periods (a-1 = 3), and each of these non-light-emitting periods has the same length.

[0078] During the dimming control period Tb, if the lengths of the non-emitting periods become uneven, flickering is easily detected; conversely, if the lengths are equal, flickering becomes less noticeable. Therefore, it is preferable that the lengths of the non-emitting periods of the organic EL element 21 become equal during the dimming control period Tb.

[0079] (Second variation) Next, refer to Figure 5 The dimming control in the display device 100 according to the second variation of this embodiment will be described. Figure 5 This diagram illustrates an example of a black insertion period Ta and a dimming control period Tb set within a frame period Tf for a pixel displayed in a display device 100 according to a second variation of an embodiment of this disclosure. Figure 5 The diagram illustrates how the dimming rate can be compared during the black insertion period (Ta) and the dimming control period (Tb), showing the cases where the dimming rate is 100%, 75%, 50%, and 25%. Figure 5 In the diagram, the horizontal axis represents time, and the vertical axis represents the amount of positive drive current IF flowing through the organic EL element 21.

[0080] The second variation of this embodiment relates to a display device 100 that has the same configuration as the display device 100 of this embodiment. Therefore, the same reference numerals are used to label the same parts and their descriptions are omitted.

[0081] In the display device 100 of this embodiment, the black insertion rate of Tf during one frame is 50%, while in the display device 100 of the second variation of this embodiment, the black insertion rate of Tf during one frame is 35%.

[0082] Furthermore, in the display device 100 of this embodiment, the number of pulses in Tb during the dimming control period is 2 regardless of the dimming rate. In contrast, in the display device 100 of the second variation of this embodiment, the difference is that the number of pulses in Tb during the dimming control period varies according to the dimming rate.

[0083] Here, when the dimming rate set during the dimming control period Tb is reduced, the brightness of the light emitted by the display unit 10 decreases, sometimes causing noticeable flickering in the displayed image. Therefore, in the display device 100 according to the second variation of this embodiment, the number of pulses during the dimming period Tb is changed by changing the dimming rate according to the set dimming rate.

[0084] Specifically, in the display device 100 according to the second variation of this embodiment, control is performed as follows: when the set dimming rate is reduced, the EMI control circuit 12 inputs an EMI signal to the third transistor T3, and the number of pulses of the organic EL element 21 of Tb increases during dimming control. That is, based on the input EMI signal, the third transistor T3 increases the number of times it switches between the on and off states, and increases the number of times the organic EL element 21 emits light.

[0085] Even when the dimming rate is reduced in this way, flickering in the displayed image can be suppressed by increasing the number of pulses in Tb during dimming control.

[0086] Furthermore, if the dimming rate decreases, the emission period becomes relatively shorter during the dimming control period Tb, and therefore the non-emission period becomes relatively longer. In this case, by increasing the number of pulses during the dimming control period Tb, the period during which Tb is continuously non-emission-producing can be shortened. Therefore, it is possible to clearly distinguish between the non-emission period and the black insertion period Ta during the dimming control period Tb.

[0087] In the second variation of this embodiment, the display device 100, such as Figure 5 As shown, the dimming control period Tb is displayed when the black insertion rate in Tf is 35% and the dimming rate is 75%, 50%, and 25% during a 1-frame period.

[0088] When the dimming rate is 75%, the number of pulses in the dimming control period Tb is 3. Furthermore, the lengths of the emission periods are the same during the dimming control period Tb. Therefore, the length of a single emission period for the organic EL element 21 becomes (1 / 3) × 0.75 × the dimming control period Tb.

[0089] When the dimming rate is 50%, the number of pulses in the dimming control period Tb is 4. Furthermore, the lengths of the emission periods are the same during the dimming control period Tb. Therefore, the length of a single emission period for the organic EL element 21 becomes (1 / 4) × 0.50 × dimming control period Tb.

[0090] When the dimming rate is 25%, the number of pulses in the dimming control period Tb is 5. Furthermore, the lengths of the emission periods are the same during the dimming control period Tb. Therefore, the length of a single emission period for the organic EL element 21 becomes (1 / 5) × 0.25 × the dimming control period Tb.

[0091] Thus, in the display device 100 according to the second variation of this embodiment, it is configured such that when the set dimming rate is reduced, the number of pulses in the dimming control period Tb is increased.

[0092] Furthermore, in the display device 100 of the second variation of this embodiment, from the viewpoint of suppressing flicker, it is preferable that the lengths of the non-light-emitting periods of the organic EL element 21 are the same during the dimming control period Tb.

[0093] (Third variation) Next, refer to Figure 6 and Figure 7 The dimming control in the display device 100 according to the third variation of this embodiment will be described. Figure 6 This diagram illustrates an example of a black insertion period Ta and a dimming control period Tb set within a frame period Tf for a pixel displayed in a display device 100 according to a third variation of an embodiment of this disclosure. Figure 6 The diagram illustrates the cases with a black insertion rate of 60%, 40%, and 20%, in a way that allows for comparison between the black insertion period Ta and the dimming control period Tb. Figure 6 In the diagram, the horizontal axis represents time, and the vertical axis represents the amount of positive drive current IF flowing through the organic EL element 21. Figure 7 This is a graph showing the correspondence between the black insertion rate, relative dimming rate, and pulse number of a pixel displayed in a display device 100 according to a third variation of the embodiment disclosed herein, set during a frame period Tf.

[0094] The third variation of this embodiment relates to a display device 100 that has the same configuration as the display device 100 of this embodiment. Therefore, the same reference numerals are used to label the same parts and their descriptions are omitted.

[0095] In the display device 100 of this embodiment, the black insertion rate of Tf during one frame is 50%. In contrast, in the display device 100 of the third variation of this embodiment, the black insertion rate of Tf during one frame is changed to 60%, 40%, or 20%.

[0096] Furthermore, in the display device 100 of this embodiment, the dimming rate of Tb during dimming control is set to 75%, 50%, and 25%. In contrast, in the display device 100 of the third variation of this embodiment, the difference is that the dimming rate of Tf is set to constant during one frame, regardless of the black insertion rate.

[0097] That is, in the display device 100 according to this embodiment, for multiple frame periods constituting the image to be displayed, the black insertion period Ta contained in each frame period Tf is set to be constant. However, it is conceivable that images with different moving content, such as moving images and landscape images, are displayed sequentially in the display device 100. In this case, in the display device 100 according to the third variation of this embodiment, for each displayed image, the black insertion rate / dimming rate determination unit 51 determines the black insertion rate in the frame period Tf, and inputs the EMI signal that specifies the on / off control of the third transistor T3 from the EMI control circuit 12 to the third transistor T3 in a manner that achieves the determined black insertion rate.

[0098] However, if the black insertion period Ta set in one frame period Tf is increased, the dimming control period Tb becomes smaller. Therefore, even if the dimming rate is the same relative to the dimming control period Tb, the brightness of the light emitted from the display unit 10 decreases. In the case where it is necessary to keep the brightness constant relative to one frame period Tf even if the black insertion rate in one frame period Tf is changed, in the display device 100 according to the third modification of this embodiment, such as... Figure 6 and Figure 7 As shown, dimming control is performed by keeping the emission period bit constant during the dimming control period Tb, so that the dimming rate is constant relative to the 1-frame period Tf. Furthermore, the dimming rate relative to the 1-frame period Tf is referred to as the absolute dimming rate. In contrast, the dimming rate relative to the dimming control period Tb is referred to as the relative dimming rate.

[0099] Here, as mentioned above, the relationship between the black insertion rate and the dimming control period Tb is that the smaller the black insertion rate, the longer the dimming control period Tb. Furthermore, under the condition that the absolute dimming rate is constant, flicker tends to become more pronounced when the dimming control period Tb increases.

[0100] Therefore, in the display device 100 according to the third variation of this embodiment, when the set black insertion rate decreases and the set dimming control period Tb becomes longer, the EMI control circuit 12 inputs an EMI signal to the third transistor T3 to control the device by increasing the number of pulses during the dimming control period Tb. That is, based on the input EMI signal, the third transistor T3 increases the number of times it switches between the on and off states and increases the number of times the organic EL element 21 emits light.

[0101] Specifically, when the absolute dimming rate is set to 20% and the black insertion rate is set to 60%, the number of pulses in Tb during dimming control is set to 3. In this case, the relative dimming rate is 50%. Furthermore, when the absolute dimming rate is set to 20% and the black insertion rate is set to 40%, the number of pulses in Tb during dimming control is set to 4. In this case, the relative dimming rate is 33.3%. Additionally, when the absolute dimming rate is set to 20% and the black insertion rate is set to 20%, the number of pulses in Tb during dimming control is set to 5. In this case, the relative dimming rate is 25%.

[0102] Thus, in the display device 100 according to the third variation of this embodiment, when the absolute dimming rate is constant, the relative dimming rate is set in such a way that the absolute dimming rate is constant when the black insertion rate is changed, and the number of pulses in Tb during dimming control increases as the black insertion rate decreases.

[0103] When the black insertion rate set as described above decreases, the dimming control period becomes longer, and therefore the non-light-emitting period within the dimming control period also becomes relatively longer. In this case, in the display device 100 according to the third variation of this embodiment, since the number of pulses in the dimming control period Tb can be increased, the time during which Tb continuously remains non-light-emitting during the dimming control period can be shortened. Therefore, the non-light-emitting period and the black insertion period Ta within the dimming control period Tb can be clearly distinguished.

[0104] Furthermore, even if the configuration changes the number of pulses in the dimming control period Tb according to the black insertion rate, from the viewpoint of suppressing flicker, it is preferable to make the light emission interval of the organic EL element 21 equal during the dimming control period Tb.

[0105] Furthermore, as described above, the relationship between the black insertion rate and the dimming control period Tb is that the lower the black insertion rate, the longer the dimming control period Tb. Therefore, the smaller the black insertion rate, the greater the maximum brightness of the light emitted from the display unit 10. On the other hand, the smaller the black insertion rate, the less effective the motion blur suppression. Conversely, the larger the black insertion rate, the smaller the maximum brightness of the light emitted from the display unit 10. On the other hand, the larger the black insertion rate, the greater the motion blur suppression. Thus, in the display device 100 according to the third modification of this embodiment, the black insertion rate can be changed simply based on whether the displayed image content preferably has a large maximum brightness or preferably suppresses motion blur.

Claims

1. A display device, comprising: A multi-pixel circuit has a self-emissive element and a switching element that switches the self-emissive element from emitting light to not emitting light, and is respectively arranged corresponding to the multi-pixel; as well as The control circuit controls the plurality of pixel circuits respectively based on the image signal of the displayed image. In one frame of the plurality of frames constituting the image, the longest of the plurality of periods during which the self-emissive element is continuously not emitting light is designated as the black insertion period, and the remaining periods of the one frame excluding the black insertion period are designated as dimming control periods. The control circuit controls the switching element to switch between emitting light and not emitting light, such that the self-emitting element emits light for at least a constant period from the beginning of the dimming control period and a constant period until the end of the dimming control period. When the sum of the light emission periods of the self-emissive element during the dimming control period is set as the dimming rate, When the dimming rate set during the dimming control period is reduced, the control circuit controls the switching between emitting light and not emitting light by the switching element in a manner that increases the number of times the self-emitting element emits light during the dimming control period.

2. The display device according to claim 1, characterized in that, During the dimming control, the emission periods of the self-emissive elements are each of the same length.

3. The display device according to claim 1 or 2, characterized in that, When the number of times the self-emissive element emits light during the dimming control period is set to n, if n is 3 or more, the lengths of the (n-1) non-emissive periods during the dimming control period are all the same.

4. The display device according to any one of claims 1 to 3, characterized in that, When the proportion of the black insertion period within the 1-frame period is set as the black insertion rate... When the black insertion rate set during the 1-frame period is reduced, the control circuit controls the switching between light emission and non-light emission performed by the switching element in a manner that increases the number of times the self-emissive element emits light during the dimming control period.

5. The display device according to claim 4, characterized in that, Includes a black insertion rate determination unit that determines the black insertion rate. The control circuit controls the switching between emitting light and not emitting light by the switching element based on the black insertion rate determined by the black insertion rate determination unit.

6. The display device according to claim 5, characterized in that, The control circuit controls the switching of light emission and non-light emission by the switching element for each of the plurality of frames, in a manner that becomes the black insertion rate determined by the black insertion rate determination unit.

7. The display device according to claim 5 or 6, characterized in that, The black insertion rate determination unit determines the black insertion rate based on the type of the displayed image.

8. The display device according to claim 5 or 6, characterized in that, The black insertion rate determination unit detects the motion of the image based on the image signal and determines the black insertion rate based on the motion.

9. The display device according to claim 1, characterized in that, Includes a dimming rate determination unit that determines the dimming rate. The control circuit controls the switching between emitting light and not emitting light by the switching element based on the dimming rate determined by the dimming rate determination unit.

10. The display device according to claim 9, characterized in that, This includes an input section for inputting the set value of the dimming rate. The dimming rate determination unit determines the dimming rate based on the dimming rate setting value input from the input unit.

11. The display device according to claim 9, characterized in that, Includes sensors that measure the brightness around the display device. The dimming rate determination unit determines the dimming rate based on a measurement value representing the ambient brightness measured from the sensor.

12. The display device according to claim 9, characterized in that, The dimming rate determination unit calculates the average brightness value of the displayed image and sets the dimming rate based on the average brightness value.

13. A display device, comprising: A multi-pixel circuit has a self-emissive element and a switching element that switches the self-emissive element from emitting light to not emitting light, and is respectively arranged corresponding to the multi-pixel; as well as The control circuit controls the plurality of pixel circuits respectively based on the image signal of the displayed image. In one frame of the plurality of frames constituting the image, the longest of the plurality of periods during which the self-emissive element is continuously not emitting light is designated as the black insertion period, and the remaining periods of the one frame excluding the black insertion period are designated as dimming control periods. The control circuit controls the switching element to switch between emitting light and not emitting light, such that the self-emitting element emits light for at least a constant period from the beginning of the dimming control period and a constant period until the end of the dimming control period. When the proportion of the black insertion period within the 1-frame period is set as the black insertion rate... When the black insertion rate set during the 1-frame period is reduced, the control circuit controls the switching between light emission and non-light emission performed by the switching element in a manner that increases the number of times the self-emissive element emits light during the dimming control period.

14. The display device according to claim 13, characterized in that, During the dimming control, the emission periods of the self-emissive elements are each of the same length.

15. The display device according to claim 13 or 14, characterized in that, When the number of times the self-emissive element emits light during the dimming control period is set to n, if n is 3 or more, the lengths of the (n-1) non-emissive periods during the dimming control period are all the same.

16. The display device according to any one of claims 13 to 15, characterized in that, Includes a black insertion rate determination unit that determines the black insertion rate. The control circuit controls the switching between emitting light and not emitting light by the switching element based on the black insertion rate determined by the black insertion rate determination unit.

17. The display device according to claim 16, characterized in that, The control circuit controls the switching of light emission and non-light emission by the switching element for each of the plurality of frames, in a manner that becomes the black insertion rate determined by the black insertion rate determination unit.

18. The display device according to claim 16 or 17, characterized in that, The black insertion rate determination unit determines the black insertion rate based on the type of the displayed image.

19. The display device according to claim 16 or 17, characterized in that, The black insertion rate determination unit detects the motion of the image based on the image signal and determines the black insertion rate based on the motion.

Images