Electronic paper display device and electronic paper display panel

Abstract

The present application provides an electronic paper display device including an electronic paper display panel. The electronic paper display panel includes a plurality of pixel circuits arranged in an array. Each pixel circuit includes a transistor element. The transistor element is an oxide transistor. A set of signal waveforms used to drive the pixel circuits to display an image frame includes a plurality of subframes. In a low frequency mode, a number of subframes of the image frame is less than 10.

Description

Technical Field

[0001] This invention relates to a display device and its display panel, and more particularly to an electronic paper display device and its electronic paper display panel. Background Technology

[0002] Current wireless charging is passive, with both the transmitter and receiver fixed in place. The transmitter sends a fixed amount of energy and cannot dynamically adjust the energy, transmission angle, or transmission time to meet the receiver's needs. Electronic paper displays (such as electrophoretic displays) can be used as electric tags. Electric tag applications require extremely low power consumption and must be driven by wireless charging devices. For example, charging devices can charge electric tags via Near-Field Communication (NFC).

[0003] In existing technologies, power consumption can be reduced by adjusting the material of the front panel laminate (FPL) to lower the driving voltage of the electronic tag. However, this method of reducing power consumption may degrade the display quality of the electronic tag. Another approach is to reduce the update frequency of the electronic tag to lower power consumption. However, this method increases the page update time of the electronic tag, which is impractical.

[0004] Therefore, it is necessary to design an electronic paper display device with low power consumption and good display quality. Summary of the Invention

[0005] This invention provides an electronic paper display device and its electronic paper display panel. The electronic paper display device features low power consumption and provides good display quality.

[0006] The electronic paper display device of the present invention includes an electronic paper display panel. The electronic paper display panel includes a plurality of pixel circuits arranged in an array. Each pixel circuit includes a transistor element. The transistor element is an oxide transistor. A set of signal waveforms for driving the pixel circuits to display an image includes a plurality of frames. In a low-frequency mode, the number of frames is less than 10.

[0007] In one embodiment of the invention, each pixel circuit further includes a storage capacitor coupled to a transistor element. The capacitance density of the storage capacitor is greater than 50 microfarads per square meter.

[0008] In one embodiment of the present invention, in low-frequency mode, the screen refresh rate of the electronic paper display panel is less than 30 Hz.

[0009] In one embodiment of the present invention, the material of the channel layer of the oxide transistor is indium gallium zinc oxide or indium zinc tin oxide.

[0010] The electronic paper display panel of this invention includes a plurality of pixel circuits arranged in an array. Each pixel circuit includes a transistor element, a storage capacitor, and a pixel capacitor. Data voltage drives the storage capacitor and pixel capacitor through the transistor element to enable the electronic paper display panel to display an image. The transistor element is an oxide transistor. The capacitance density of the storage capacitor is greater than 50 microfarads / m².

[0011] In one embodiment of the present invention, a set of signal waveforms used to drive pixel circuits to display an image includes multiple frames. In the low-frequency mode, the number of frames is less than 10. Attached Figure Description

[0012] The accompanying drawings are included to further illustrate the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0013] Figure 1 A schematic diagram of an electronic paper display device according to an embodiment of the present invention is shown;

[0014] Figure 2 Show Figure 1 A schematic diagram of the pixel circuit of the electronic paper display device in the embodiment;

[0015] Figure 3 Show Figure 2 A schematic diagram of the transistor element in the embodiment;

[0016] Figure 4A and Figure 4B Show respectively Figure 2 A schematic diagram of the microcapsules in the electrophoretic layer of the embodiment in different states;

[0017] Figure 5 A schematic diagram of the pixel voltage waveform according to an embodiment of the present invention is shown;

[0018] Figure 6 A schematic diagram of the pixel voltage waveform is shown according to another embodiment of the present invention;

[0019] Figure 7 and Figure 8 A schematic diagram showing the screen update time and power consumption of an electronic paper display panel;

[0020] Figure 9 This diagram illustrates the screen update time and power of an electronic paper display panel according to an embodiment of the present invention.

[0021] Explanation of icon numbers

[0022] 100: Electronic paper display device

[0023] 110: Electronic paper display panel

[0024] 111: Scan line

[0025] 112: Circuit Layer

[0026] 113: Data cable

[0027] 114: Electrophoretic layer

[0028] 116: Protective layer

[0029] 200: Pixel Circuit

[0030] 210: Transistor Components

[0031] 220: Storage capacitor

[0032] 230: Pixel Capacitor

[0033] 310: First source / drain

[0034] 320: Second source / drain

[0035] 330: Gate

[0036] 340: Channel Layer

[0037] 410: Upper electrode

[0038] 420: Lower electrode

[0039] 432: Black Particles

[0040] 434: White Particles

[0041] 600: Dashed line

[0042] P1, P2, P3: Power

[0043] t1, t2, t3: Time length

[0044] V1, V2: Voltage values

[0045] Vd: Data voltage

[0046] Vp: Pixel voltage Detailed Implementation

[0047] Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same element references are used in the drawings and description to denote the same or similar parts.

[0048] Figure 1A schematic diagram of an electronic paper display device according to an embodiment of the present invention is shown. Figure 2 Show Figure 1 A schematic diagram of the pixel circuitry of the electronic paper display device in this embodiment. Please refer to... Figure 1 The electronic paper display device 100 includes an electronic paper display panel 110. The electronic paper display panel 110 includes a layered structure such as a circuit layer 112, an electrophoretic layer 114, and a protective layer 116. The electronic paper display panel 110 includes a plurality of pixel circuits 200 arranged in an array. Each pixel circuit 200 includes a transistor element 210, a storage capacitor 220, and a pixel capacitor 230, wherein the pixel voltage of the pixel capacitor 230 is denoted as Vp. The storage capacitor 220 is coupled to the transistor element 210.

[0049] Specifically, the circuit layer 112 is, for example, a thin-film transistor substrate, including a plurality of transistor elements 210 arranged in an array. Electrophoretic ink technology is commonly referred to as electronic ink. Electronic ink is formed on a plastic film to form an electrophoretic layer 114, which is then attached to the circuit layer 112 and driven by a driver chip to display an image page. A protective layer 116 serves as a protective film to protect the layered structure of the electronic paper display panel 110.

[0050] Figure 3 Show Figure 2 A schematic diagram of the transistor element in the embodiment. Please refer to... Figure 2 and Figure 3 , Figure 2 The transistor element 210 is implemented, for example, as an oxide thin-film transistor, with the structure as follows: Figure 3 As shown. Transistor element 210 includes a first source / drain 310, a second source / drain 320, a gate 330, and a channel layer 340. The channel layer 340 is made of oxide, such as indium gallium zinc oxide (IGZO) or indium zinc tin oxide (IZTO). Oxide transistors have very low offcurrent characteristics, thus maintaining pixel voltage in low panel frequency modes. Figure 3 The oxide transistor structure and the material of the channel layer are for illustrative purposes only and are not intended to limit the invention.

[0051] Figure 4A and Figure 4B Show respectively Figure 2A schematic diagram illustrating the microcapsules in the electrophoretic layer of the embodiment under different states. Please refer to... Figure 2 , Figure 4A and Figure 4B The electrophoretic layer 114 comprises millions of microcapsules 430. Each microcapsule 430 is approximately the diameter of a human hair. Each microcapsule 430 contains electrophoretic particles, namely negatively charged white particles 434 and positively charged black particles 432, suspended in a transparent liquid. The size of the microcapsules 430 and the color of the electrophoretic particles are not intended to limit the invention. In other words, the electronic paper display device 100 can display two-color (white, black), three-color (white, red, black), four-color (white, red, yellow, black), or color images.

[0052] The upper electrode 410 and lower electrode 420 of the electrophoretic layer 114 form a pixel capacitor 230. During driving, a scan signal turns on the transistor element 210 through the scan line 111. Then, the data voltage Vd is written from the data line 113 into the pixel circuit 200 to drive the pixel circuit 200 to display an image. When the data voltage Vd is applied to the upper electrode 410 and lower electrode 420, it drives the electrophoretic particles to move. Figure 4A In this process, a negative voltage is applied to the upper electrode 410 and a positive voltage is applied to the lower electrode 420 to drive positively charged black particles 432 to move to the upper electrode 410, while negatively charged white particles 434 move to the lower electrode 420. Therefore, the pixel appears black. Figure 4B In the process, a positive voltage is applied to the upper electrode 410 and a negative voltage is applied to the lower electrode 420 to drive the positively charged black particles 432 to move to the lower electrode 420, while the negatively charged white particles 434 move to the upper electrode 410. Therefore, the pixel appears white.

[0053] In this embodiment, due to Figure 2 The transistor element 210 is implemented using an oxide transistor, thus maintaining the original voltage to drive the electrophoretic particles. In conjunction with operating the electronic paper display panel 110 in a low frame count mode, the power consumption of the electronic paper display device 100 can be effectively reduced, achieving the purpose of power saving and maintaining the display quality of the electronic paper display panel 110.

[0054] Figure 5 A schematic diagram of the pixel voltage waveform according to an embodiment of the present invention is shown. Please refer to... Figure 1 , Figure 2 and Figure 5 , Figure 5 The diagram shown is a waveform of the electronic paper display panel 110 in normal mode. In normal mode, a set of signal waveforms used to drive the pixel circuit 200 to display the image are as follows: Figure 5As shown, this includes 10 frames. During the drive, when transistor element 210 is turned on, it is similar to... Figure 5 The waveform data voltage is written from data line 113 to pixel circuit 200 to drive pixel circuit 200 to display image. When transistor element 210 is not conducting, since transistor element 210 is implemented as an oxide transistor, it has low leakage current characteristics, so the pixel voltage Vp of pixel capacitor 230 can be maintained as... Figure 5 The voltage waveform shown is, for example, maintained at a voltage value V1.

[0055] Figure 6 A schematic diagram of the pixel voltage waveform according to another embodiment of the present invention is shown. Please refer to... Figure 1 , Figure 2 and Figure 6 , Figure 6 The diagram shows the electronic paper display panel 110 operating in a low-frequency mode, for example, where the screen refresh rate of the electronic paper display panel 110 is less than 30 Hz and the number of frames is less than 10. In low-frequency mode, a set of signal waveforms used to drive the pixel circuit 200 to display the image are shown below. Figure 6 As shown, this includes two diagrams. During the drive, when transistor element 210 is turned on, it is similar to... Figure 6 The waveform data voltage is written from data line 113 to pixel circuit 200 to drive pixel circuit 200 to display image. When transistor element 210 is not conducting, since transistor element 210 is implemented as an oxide transistor, it has low leakage current characteristics, so the pixel voltage Vp of pixel capacitor 230 can be maintained as... Figure 6 The voltage waveform shown is maintained at, for example, voltage value V2. Voltage value V2 may be equal to or different from voltage value V1. This embodiment uses two frames as an example, but the content of the present invention is not limited thereto. The present invention can be used in low-frequency mode, and when the number of frames is less than 10, it can achieve the effect of saving power and maintaining image quality.

[0056] In this embodiment, the capacitance density of the storage capacitor 220 can be designed to be greater than 50 microfarads per square meter (μF / m²). 2 This helps maintain the pixel voltage Vp at the voltage value V2, thereby improving display quality.

[0057] If the transistor element 210 is not implemented using an oxide transistor, the pixel voltage of the pixel capacitor 230 may experience severe leakage, as shown by the dashed line 600, and may not be able to maintain the voltage value V2.

[0058] Figure 7 and Figure 8 This diagram illustrates the page update time and power consumption of an electronic paper display panel. Figure 9 This diagram illustrates the screen update time and power of an electronic paper display panel according to an embodiment of the present invention. Please refer to... Figures 7 to 9 ,exist Figure 7 and Figure 8 In this process, by reducing the screen refresh rate of the electronic paper display panel 110, the power consumed by the electronic paper display panel 110 can be reduced from... Figure 7 The power P1 drops to Figure 8 The power P2. However, this method of reducing power consumption simply by lowering the screen refresh rate of the electronic paper display panel 110 may increase the screen refresh time from... Figure 7 The time length t1 increases to Figure 8 The time length t2. Figure 8 and Figure 9 In this design, by increasing the capacitance density of the storage capacitor 220, for example, by designing it to be greater than 50 microfarads / meter square, the screen update time can be reduced from... Figure 8 The time length t2 is reduced to Figure 9 The time length t3. Therefore, by reducing the screen refresh rate of the electronic paper display panel 110 and increasing the capacitance density of the storage capacitor 220, power consumption can be reduced while maintaining screen quality.

[0059] In summary, in the embodiments of the present invention, since the transistor element is an oxide transistor and the storage capacitor has a high capacitance density, power consumption can be reduced while maintaining good display quality when the electronic paper display panel operates at a low screen refresh rate.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electronic paper display device, comprising: An electronic paper display panel includes a plurality of pixel circuits arranged in an array, wherein each pixel circuit includes a transistor element, wherein the transistor element is an oxide transistor, and a set of signal waveforms for driving the pixel circuit to display an image includes a plurality of frames, wherein in a low-frequency mode, the number of frames is less than 10. Each of the pixel circuits further includes a storage capacitor and a pixel capacitor, and the capacitance density of the storage capacitor is greater than 50 microfarads / meter square.

2. The electronic paper display device according to claim 1, wherein in the low-frequency mode, the screen refresh rate of the electronic paper display panel is less than 30 Hz.

3. The electronic paper display device according to claim 1, wherein the material of the channel layer of the oxide transistor is indium gallium zinc oxide or indium zinc tin oxide.

4. An electronic paper display panel, comprising a plurality of pixel circuits arranged in an array, wherein each pixel circuit comprises a transistor element, a storage capacitor and a pixel capacitor, wherein a data voltage drives the storage capacitor and the pixel capacitor through the transistor element to display an image on the electronic paper display panel, wherein the transistor element is an oxide transistor and the capacitance density of the storage capacitor is greater than 50 microfarads / m².

5. The electronic paper display panel according to claim 4, wherein a set of signal waveforms for driving the pixel circuit to display an image includes multiple frames, and in the low-frequency mode, the number of frames is less than 10.

6. The electronic paper display panel according to claim 5, wherein in the low-frequency mode, the screen refresh rate of the electronic paper display panel is less than 30 Hz.

7. The electronic paper display panel according to claim 4, wherein the material of the channel layer of the oxide transistor is indium gallium zinc oxide or indium zinc tin oxide.

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