TWI837485B - Self-luminous display device - Google Patents

Abstract

A self-luminous display device includes a self-luminous display panel, a multiplexer circuit, a source driver, a switch circuit and an anode reset circuit. The self-luminous display panel includes a plurality of pixel circuits and a plurality of source lines. Each pixel circuit has a light-emitting element and a driving circuit. The source lines are individually coupled to a part of the pixel circuits and are coupled to an anode of the light-emitting element and the driving circuit of each pixel circuit coupled thereto. The source driver is coupled to the source lines through the multiplexer circuit to provide a plurality of gamma voltages to the source lines. The anode reset circuit is coupled to the source lines through the switch circuit to provide at least one anode reset voltages to the source lines.

Description

Self-luminous display device

The present invention relates to a display device, and in particular to a self-luminous display device.

Organic Light-Emitting (OLED) is a mature display process technology. Its many advantages make it a key technology for current display devices. Among them, the advantages of OLED are: 1. High color saturation, bright colors, and high contrast; 2. Black does not emit light, which is beneficial for power saving; 3. Due to its self-luminous characteristics, it can be made thinner without backlight, which is beneficial for saving space in mobile phones; and 4. Because it is light and thin, it can be folded and bent.

However, organic light-emitting diodes have parasitic capacitance, which will affect low gray levels. Therefore, the voltage of the anode end of the organic light-emitting diode needs to be reset, but the voltage reset will increase the layout area. For example, an independent voltage line is used for voltage reset, resulting in an increase in layout area; or, when the screen update frequency decreases, leakage will affect screen jitter (flicker), which needs to be overcome by using low-temperature polycrystalline oxide (LTPO) circuits, which requires a larger circuit area.

Therefore, how to reset the voltage at the anode end of an OLED without affecting the layout area becomes an important issue in designing OLED display devices.

The present invention provides a self-luminous display device that can reset the voltage at the anode end of the light-emitting element without affecting the layout area.

The self-luminous display device of the present invention includes a self-luminous display panel, a multiplexer circuit, a source driver, a switch circuit and an anode reset circuit. The self-luminous display panel includes a plurality of pixel circuits and a plurality of source lines. The pixel circuits each have a light-emitting element and a drive circuit. The source lines are individually coupled to a portion of the pixel circuits and to the anode and the drive circuit of the light-emitting element of each coupled pixel circuit. The multiplexer circuit is coupled to the source line. The source driver is coupled to the source line through the multiplexer circuit to provide a plurality of gamma voltages to the source line. The switch circuit is coupled to the source line. The anode reset circuit is coupled to the source line through a switch circuit to provide multiple anode reset voltages to the source line.

Based on the above, in the self-luminous display device of the embodiment of the present invention, the source driver and the anode reset circuit transmit the gamma voltage and the anode reset voltage through the time-sharing shared source line, so there is no need to increase the wiring on the self-luminous display panel to transmit the anode reset voltage, that is, the voltage of the anode end of the light-emitting element can be reset without affecting the layout area.

In order to make the above features and advantages of the present invention more clearly understood, the following is a detailed description of the embodiments with the accompanying drawings.

100: Self-luminous display device

110: Control circuit

120: Source driver

130: Anode reset circuit

140: Self-luminous display panel

141:Multiplexer circuit

143:Pixel array

145: Switching circuit

a: First end

b: Second end

CP1: Current path

Cst: Capacitance

CT_R, CT_G, CT_B: Anode reset voltage

CT_SW: switch control signal

DX1: driver circuit

EM: luminescent signal

F1~F11: Screen period

Hsync: During horizontal scanning

LD1: Light-emitting element

LDX: Source line

M1~M4: transistor

Mux1~MuxN: multiplex control signal

OVDD: system voltage

OVSS: common voltage

PX, PXa: Pixel circuit

S1, S2: Scanning signal

SC1, SC2: control signal

T11~T1N, TM1~TMN: first switch

T2: Second switch

Vdata1~VdataM: Gamma voltage

Vref: reference voltage

Figure 1 is a system schematic diagram of a self-luminous display device according to an embodiment of the present invention.

Figure 2 is a circuit diagram of a self-luminous pixel according to an embodiment of the present invention.

Figure 3 is a schematic diagram of the operation timing of a self-luminous display device according to an embodiment of the present invention.

Figure 4 is a schematic diagram of the operation timing of a self-luminous display device according to another embodiment of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by ordinary technicians in the field to which the present invention belongs. It will be further understood that those terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and the present invention, and will not be interpreted as an idealized or overly formal meaning unless expressly defined as such in this document.

It should be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and/or parts, these elements, components, regions, and/or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, the "first element", "component", "region", "layer" or "part" discussed below can be referred to as a second element, component, region, layer or part without departing from the teachings of this article.

The terms used herein are for the purpose of describing specific embodiments only and are not limiting. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms, including "at least one". " or "means" and/or". As used herein, the term "and/or" includes any and all combinations of one or more of the relevant listed items. It should also be understood that when used in this specification, the term "includes" and/or "includes" specifies the presence of the features, regions, wholes, steps, operations, elements, and/or parts, but does not exclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, parts, and/or combinations thereof.

FIG1 is a system schematic diagram of a self-luminous display device according to an embodiment of the present invention. Referring to FIG1 , in the present embodiment, the self-luminous display device 100 at least includes a control circuit 110, a source driver 120, an anode reset circuit 130, and a self-luminous display panel 140. The control circuit 110 includes, for example, a timing controller, the control circuit 110 is coupled to the source driver 120 to provide a control signal SC1, coupled to the anode reset circuit 130 to provide a control signal SC2, and the control circuit 110 is coupled to the self-luminous display panel 140 to provide multiplexed control signals Mux1~MuxN and a switch control signal CT_SW, wherein N can be a positive integer.

The self-luminous display panel 140 includes a multiplexer circuit 141, a pixel array 143 and a switch circuit 145. The pixel array 143 includes a plurality of pixel circuits PX and a plurality of source lines LDX, wherein each pixel circuit PX has at least a light-emitting element LD1, a current path CP1 and a driving circuit DX1, and the current path CP1 is coupled between the light-emitting element LD1 and the driving circuit DX1, wherein the light-emitting element LD1 may be an organic light-emitting diode, but the embodiment of the present invention is not limited thereto.

The source lines LDX are individually coupled to a portion of the pixel circuits PX (e.g., a row of pixel circuits PX), and each source line LDX is coupled to the anode of the light-emitting element LD1 and the driving circuit DX1 of each coupled pixel circuit PX.

The multiplexer circuit 141 is coupled to the first end a of the source lines LDX, and the source driver 120 is coupled to the source lines LDX through the multiplexer circuit 141 to provide multiple gamma voltages Vdata1~VdataM to the source lines LDX through the multiplexer circuit 141. The switch circuit 145 is coupled to the second end b of the source lines LDX, and the anode reset circuit 130 is coupled to the source lines LDX through the switch circuit 145 to provide multiple anode reset voltages (e.g., CT_R, CT_G, CT_B) to the source lines LDX through the switch circuit 145.

In this embodiment, since the pixel circuit PX performs voltage reset and data writing at different times, the first on time of the multiplexer circuit 141 and the second on time of the switch circuit 145 do not overlap. In other words, when the voltage is reset, the switch circuit 145 is turned on and the multiplexer circuit 141 is turned off; and when the data is written, the multiplexer circuit 141 is turned on and the switch circuit 145 is turned off.

Thus, since the source driver 120 and the anode reset circuit 130 transmit the gamma voltages Vdata1~VdataM and the anode reset voltages CT_R, CT_G, and CT_B through the time-sharing shared source line LDX, it is not necessary to increase the wiring on the self-luminous display panel 140 to transmit the anode reset voltages CT_R, CT_G, and CT_B, that is, the voltage of the anode end of the light-emitting element LD1 can be reset without affecting the layout area. Moreover, the anode reset circuit 130 disposed outside the self-luminous display panel 140 has a driving capability that is independent of the process of the self-luminous display panel 140, so the anode reset voltages CT_R, CT_G, and CT_B can be set according to circuit requirements, that is, the voltage range of the anode reset voltages CT_R, CT_G, and CT_B is not limited by the process of the self-luminous display panel 140.

In the embodiment of the present invention, the multiplexer circuit 141 includes a plurality of first switches (e.g., T11~T1N, TM1~TMN), and the first switches (e.g., T11~T1N, TM1~TMN) receive one of the multiplexing control signals Mux1~MuxN respectively and are coupled between the corresponding source line LDX and the source driver 120 respectively, wherein M can be a positive integer, and NxM can be equal to the number of source lines LDX. For example, the first switches T11, ..., and TM1 receive the multiplexing control signal Mux1, and the first switches T1N, ..., and TMN receive the multiplexing control signal MuxN.

In addition, the first switches (e.g., T11~T1N, TM1~TMN) are divided into multiple subsets, and the first switches in each subset (e.g., T11~T1N, TM1~TMN) receive the same gamma voltage (e.g., Vdata1~VdataM). For example, the first switches T11~T1N can be regarded as a subset (i.e., a multiplexer) and receive the gamma voltage Vdata1, and the first switches TM1~TMN can be regarded as another subset (i.e., another multiplexer) and receive the gamma voltage VdataM.

In the embodiment of the present invention, the switch circuit 145 includes a plurality of second switches T2, which receive the switch control signal CT_SW together and are individually coupled between the corresponding source line LDX and the anode reset circuit 130. Since driving all pixel circuits PX at the same time requires a high driving capability (e.g., current), the pixel circuits PX can be divided into a plurality of groups to provide a plurality of anode reset voltages (e.g., CT_R, CT_G, CT_B).

Furthermore, the pixel circuit PX can be divided into a red group, a green group and a blue group according to color, and the anode reset voltages CT_R, CT_G, and CT_B can correspond to the red group, the green group and the blue group respectively, so the anode reset voltages CT_R, CT_G, and CT_B can be set (or adjusted) according to the requirements of the red group, the green group and the blue group respectively. In addition, when the anode reset circuit 130 has sufficient driving capability, only one anode reset voltage can be provided, and the embodiment of the present invention is not limited thereto.

In this embodiment, the multiplexer circuit 141 and the switch circuit 145 are configured on the self-luminous display panel 140, but in other embodiments, the multiplexer circuit 141 and the switch circuit 145 can be configured outside the self-luminous display panel 140, which can be determined according to the circuit design, and the embodiments of the present invention are not limited thereto.

FIG2 is a circuit diagram of a pixel circuit of a self-luminous display panel according to an embodiment of the present invention. Please refer to FIG1 and FIG2. In this embodiment, the driving circuit DX1 of the pixel circuit PX includes a transistor M1 and a capacitor Cst, and the current path CP1 of the pixel circuit PX includes transistors M2 to M4, wherein the transistors M1 to M4 are N-type transistors, but the embodiment of the present invention is not limited thereto.

The first end of transistor M1 receives reference voltage Vref, and the control end of transistor M1 receives scanning signal S1. Capacitor Cst is coupled between the second end of transistor M1 and source line LDX. The first end of transistor M2 receives system voltage OVDD, and the control end of transistor M2 is coupled to the second end of transistor M1. The first end of transistor M4 is coupled to the second end of transistor M2, and the control end of transistor M4 receives luminous signal EM. The first end of transistor M3 is coupled to source line LDX, the control end of transistor M3 receives scanning signal S2, and the second end of transistor M2 is coupled to the second end of transistor M4. Light-emitting element LD1 is coupled between the second end of transistor M4 and common voltage OVSS.

In this embodiment, the transistors M1 to M4 are N-type transistors, so the anode reset voltage (such as CT_R, CT_G, CT_B) can be less than the common voltage OVSS received by the pixel circuit PX, so as to completely eliminate the voltage drop of the parasitic capacitance of the light-emitting element LD1. On the contrary, if the transistors M1 to M4 are P-type transistors, the structure of the pixel circuit PX will be upside down, so the anode reset voltage (such as CT_R, CT_G, CT_B) can be greater than the common voltage (such as OVSS) received by the pixel circuit PX, so as to completely eliminate the voltage drop of the parasitic capacitance of the light-emitting element LD1. According to the above, the anode reset voltage (such as CT_R, CT_G, CT_B) can be different from the common voltage OVSS received by these pixel circuits PX. Moreover, based on the common voltage (such as OVSS), the anode reset voltage (such as CT_R, CT_G, CT_B) output by the anode reset circuit 130 can be a positive voltage or a negative voltage, but the embodiment of the present invention is not limited thereto.

FIG3 is a schematic diagram of the operation timing of the self-luminous display device according to an embodiment of the present invention. Referring to FIG1 and FIG3, in this embodiment, the self-luminous display device 100 can generally operate in a normal mode and a sleep mode. When the self-luminous display device 100 operates in the normal mode (i.e., in the frame periods F1, F8, and F9), the self-luminous display device 100 is activated to update the image displayed by the self-luminous display panel 140. When the sleep mode is in sleep mode (i.e., in the frame periods F2 to F7), the self-luminous display device 100 will basically display a black image, but will still be activated in some frame periods (e.g., frame periods F2 and F5) to update the black image displayed by the self-luminous display panel 140 to maintain the stability of the image. In the remaining frame periods (e.g., frame periods F3, F4, F6 and F7), the self-luminous display device 100 will ignore the image update action.

In this embodiment, during the frame period (e.g., frame periods F3, F4, F6, and F7) in which the self-luminous display device 100 ignores the action of image updating, the voltage of the anode of the light-emitting element LD1 of the pixel circuit PX can be reset during the entire frame period, that is, during the frame periods F3, F4, F6, and F7 in which the action of image updating is ignored, the conduction time (i.e., the second conduction time) of the second switch T2 of the switch circuit 145 can last for more than one frame period.

FIG4 is a timing diagram of the operation of a self-luminous display device according to another embodiment of the present invention. Referring to FIG1 and FIG4, in this embodiment, when the self-luminous display device 100 operates in a normal mode, in one horizontal scanning period Hsync, the first switches (e.g., T11~T1N, TM1~TMN) of the multiplexer circuit 141 can be turned on in sequence, that is, the multiplexing control signals Mux1~MuxN are enabled in sequence, so as to transmit the multiple gamma voltages Vdata1~VdataM provided by the source driver 120 to the source line LDX, so as to be written into the driver circuit DX1 of a row of pixel circuits PX. When the driving circuit DX1 of a row of pixel circuits PX performs gamma voltage writing, the luminous signal EM and the switch control signal CT_SW are disabled, that is, the luminous element LD1 of the pixel circuit PX is not lit and the second switch T2 of the switch circuit 145 is not turned on to avoid affecting the voltage writing.

When the gamma voltage of the driving circuit DX1 of all pixel circuits PX is updated, the luminous signal EM is enabled to light up the luminous elements LD1 of all pixel circuits PX. At this time, the multiplexing control signals Mux1~MuxN and the switch control signal CT_SW are disabled, that is, the first switch (e.g., T11~T1N, TM1~TMN) of the multiplexer circuit 141 and the second switch T2 of the switch circuit 145 will not be turned on to avoid affecting the display effect of the luminous element LD1 of the pixel circuit PX. Secondly, when the voltage of the anode terminal of the light-emitting element LD1 is reset, the switch control signal CT_SW is enabled to turn on the second switch T2 of the switch circuit 145. At this time, the light-emitting signal EM and the multiplexing control signals Mux1~MuxN are disabled to avoid affecting the voltage reset effect of the light-emitting element LD1.

In this embodiment, when the self-luminous display device 100 operates in normal mode, the self-luminous display device 100 will update the data (or voltage) of the pixel circuit PX. At this time, the self-luminous display device 100 can use the horizontal scanning period Hsync that is not used for data (or voltage) update in the picture period (such as the picture period F10 or F11) to reset the voltage of the light-emitting element LD1. In other words, the self-luminous display device 100 can use 0.5 horizontal scanning period Hsync or more than 1 horizontal scanning period Hsync to reset the voltage of the light-emitting element LD1, that is, the conduction time (i.e., the second conduction time) of the second switch T2 of the switch circuit 145 can last for more than 0.5 horizontal scanning period Hsync. This can be determined according to the circuit design, and the embodiment of the present invention does not take this as the case.

In summary, in the self-luminous display device of the embodiment of the present invention, the source driver and the anode reset circuit transmit the gamma voltage and the anode reset voltage by sharing the source line in time, so there is no need to increase the wiring on the self-luminous display panel to transmit the anode reset voltage, that is, the voltage of the anode end of the light-emitting element can be reset without affecting the layout area. In addition, the anode reset circuit configured outside the self-luminous display panel has no relation to the process of the self-luminous display panel because of its driving ability, so the anode reset voltage can be set according to the circuit requirements, that is, the voltage range of the anode reset voltage is not limited by the process of the self-luminous display panel.

Although the present invention has been disclosed as above by the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the attached patent application.

100: Self-luminous display device

110: Control circuit

120: Source driver

130: Anode reset circuit

140: Self-luminous display panel

141:Multiplexer circuit

143:Pixel array

145: Switching circuit

a: First end

b: Second end

CP1: Current path

CT_R, CT_G, CT_B: Anode reset voltage

CT_SW: switch control signal

DX1: driver circuit

LD1: Light-emitting element

LDX: Source line

Mux1~MuxN: multiplex control signal

PX: Pixel circuit

SC1, SC2: control signal

T11~T1N, TM1~TMN: first switch

T2: Second switch

Vdata1~VdataM: Gamma voltage

Claims (13)

A self-luminous display device includes: a self-luminous display panel including: a plurality of pixel circuits, each having a light-emitting element and a driving circuit; and a plurality of source lines, each coupled to a portion of the pixel circuits and coupled to an anode of the light-emitting element of each coupled pixel circuit and the driving circuit; a multiplexer circuit coupled to the source lines; and a source driver, through the multiplexer circuit. A circuit is coupled to the source lines to provide multiple gamma voltages to the source lines; a switch circuit is coupled to the source lines; and an anode reset circuit is coupled to the source lines through the switch circuit to provide at least one anode reset voltage to the source lines, wherein when the self-luminous display device operates in a sleep mode, the self-luminous display device is activated during a partial screen period to update the image based on previous image information. A self-luminous display device as described in claim 1, wherein a first on-time of the multiplexer circuit and a second on-time of the switch circuit do not overlap. A self-luminous display device as described in claim 2, wherein the second on-time lasts for more than 0.5 horizontal scanning periods. A self-luminous display device as described in claim 3, wherein when the self-luminous display device operates in the sleep mode, the second on-time lasts for more than one screen period. A self-luminous display device as described in claim 4, wherein the duration of the second on-time is interrupted before the self-luminous display device switches from the sleep mode to a normal mode. A self-luminous display device as described in claim 1, wherein the multiplexer circuit includes a plurality of first switches, each receiving a multiplexing control signal and each coupled between a corresponding source line and the source driver. A self-luminous display device as described in claim 1, wherein the switch circuit includes a plurality of second switches, which jointly receive a switch control signal and are individually coupled between the corresponding source line and the anode reset circuit. A self-luminous display device as described in claim 1, wherein the at least one anode reset voltage is different from a common voltage commonly received by the pixel circuits. A self-luminous display device as described in claim 8, wherein the at least one anode reset voltage is greater than the common voltage. A self-luminous display device as described in claim 8, wherein the at least one anode reset voltage is less than the common voltage. The self-luminous display device as described in claim 1, wherein the multiplexer circuit and the switch circuit are configured on the self-luminous display panel. A self-luminous display device as described in claim 11, wherein the multiplexer circuit is coupled to the first ends of the source lines, and the switch circuit is coupled to the second ends of the source lines. A self-luminous display device as described in claim 1, wherein the light-emitting element includes an organic light-emitting diode.

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