Electronic paper driving circuit and display device

Abstract

The utility model discloses an electronic paper driving circuit and a display device, and relates to the technical field of electronic paper, and the electronic paper driving circuit is characterized in that an MCU transmits a digital signal with time sequence and direction control to a shift register; the shift register stores the digital signal, adjusts the amplitude of the digital signal according to the magnitude of the input voltage, and sequentially transmits the digital signal to each driving circuit unit according to a time sequence; the drive circuit unit converts an input digital signal into an electric signal, controls the pixel state on the electronic paper based on the field effect, and regulates and controls the refresh frequency according to the amplitude of the electric signal. According to the utility model, the push-pull circuit structure composed of the P-type field effect transistor and the N-type field effect transistor is adopted, so that not only is the cost reduced, but also enough driving capability is ensured, and the push-pull circuit is suitable for application scenes with low cost, low refresh rate and low power consumption.

Description

Technical Field

[0001] This utility model relates to the field of electronic paper technology, specifically to an electronic paper driving circuit and display device. Background Technology

[0002] Electronic paper display (EPD), also known as electronic ink screen, is a display technology that mimics the reading experience of traditional paper books. It is renowned for its low power consumption, high contrast, and eye-friendly characteristics, and is widely used in color-changing vehicle skins, interior architectural decorations, color-changing handbags, color-changing insulated cups, e-book readers, digital signage, smartwatches, and other portable devices.

[0003] Although electronic paper is widely used in various devices due to its low power consumption, high contrast and eye-friendly characteristics, existing electronic paper driving circuits still have some significant limitations and shortcomings, which affect their performance in a wider range of application scenarios. Utility Model Content

[0004] To address some shortcomings in existing electronic paper technology, this invention proposes an electronic paper driving circuit, comprising:

[0005] An adjustable boost circuit is used to control the voltage of the input shift register;

[0006] MCU is used to transmit digital signals with timing and direction control to shift registers;

[0007] The shift register is used to store digital signals, adjust the amplitude of the digital signals according to the input voltage, and transmit the digital signals to each drive circuit unit in sequence according to the timing.

[0008] The driving circuit unit is used to convert the input digital signal into an electrical signal, control the pixel state on the electronic paper based on the field effect, and adjust the refresh frequency according to the amplitude of the electrical signal.

[0009] Furthermore, the adjustable boost circuit uses a boost converter to adjust the output voltage.

[0010] Furthermore, the MCU is an MCU based on the ARM Cortex-M core.

[0011] Furthermore, the shift register uses a driver IC based on the SN74LVC16T245 model for synchronous serial input and parallel output of digital signals.

[0012] Furthermore, when the MCU has sufficient I / O ports, each drive circuit unit is independently controlled by the MCU's I / O ports; when the MCU has insufficient I / O ports, each drive circuit unit is controlled by cascading serial-to-parallel conversion using shift registers.

[0013] Furthermore, all the driving circuit units adopt a push-pull circuit under field effect control to drive the electronic paper.

[0014] Furthermore, the push-pull circuit consists of two field-effect transistors, wherein the upper transistor is a P-type field-effect transistor and the lower transistor is an N-type field-effect transistor.

[0015] Furthermore, the source of the P-type field-effect transistor is grounded, and the gate is connected to a digital signal through a first resistor; the source of the N-type field-effect transistor is connected to a working voltage, and the gate is connected to a digital signal through a first resistor; the drain of the P-type field-effect transistor is connected to the drain of the N-type field-effect transistor, and a driving voltage is output to the color block corresponding to the current driving circuit unit in the electronic paper.

[0016] Furthermore, the display changes of the electronic paper are achieved by controlling the movement of the microcapsules inside the electronic paper through a drive circuit unit.

[0017] This utility model also includes an electronic paper display device, comprising the aforementioned electronic paper driving circuit.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] (1) The electronic paper driving circuit and display device described in this utility model can significantly accelerate the movement speed of electrophoretic particles by optimizing voltage regulation and pulse control technology, thereby achieving faster screen refresh. This is especially important for dynamic content display (such as color changing effect, color control, animation, video playback) and can provide a smoother user experience.

[0020] (2) Each channel adopts a push-pull circuit structure composed of P-type and N-type field-effect transistors, which not only reduces the cost but also ensures sufficient driving capability, making it suitable for low-cost, low-refresh-rate, and low-power application scenarios.

[0021] (3) By introducing partition driving technology and the characteristics of field-effect transistors, the intermediate loss is small, and only the part that needs to be updated is refreshed instead of the entire screen, which further improves the refresh speed and reduces unnecessary power consumption.

[0022] (4) The number of common terminals can be increased or decreased as needed, making the driving circuit highly expandable and flexible, and able to adapt to electronic paper applications of different scales and complexities. Attached Figure Description

[0023] Figure 1 This is a modular schematic diagram of an electronic paper driving circuit and display device;

[0024] Figure 2 This is a schematic diagram of the drive circuit unit circuit structure. Detailed Implementation

[0025] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0026] While e-paper technology excels at simulating traditional paper reading and the experience of objects changing color like skin, and has significant advantages in specific applications, it still has some limitations and drawbacks:

[0027] One of the main drawbacks of e-paper is its relatively low refresh rate and high driving voltage. When used to display objects as colored skin, the display area often reaches several square meters or more, requiring greater driving power, which limits its effectiveness when displaying dynamic content. Compared to LCD or OLED screens, e-paper updates images more slowly, resulting in noticeable lag and ghosting when playing videos or performing fast scrolling, impacting the user experience. Furthermore, although color e-paper has been developed, its color reproduction and contrast are still inferior to traditional LCD screens, limiting the expressiveness of images and videos. Another issue is viewing angle; while most e-paper displays offer good clarity from the front, color and contrast may decrease when viewed from the side, reducing comfort from multiple angles. Finally, in terms of interactive functionality, e-paper typically does not support touch operation or only supports limited gesture operations, which may not be intuitive or convenient for users accustomed to the rich interactive experiences of smartphones and tablets. These factors combined make e-paper more suitable for displaying static content, such as books, documents, and static advertisements, while facing challenges in applications requiring highly interactive and dynamic content display.

[0028] To solve the above problems, such as Figure 1 As shown, this utility model proposes an electronic paper driving circuit, comprising:

[0029] An adjustable boost circuit is used to control the voltage of the input shift register;

[0030] MCU (general-purpose MCU based on ARM Cortex-M core) is used to transmit digital signals with timing and direction control to shift registers;

[0031] The shift register (using the SN74LVC16T245 driver IC, or optionally a shift register chip with push-pull output, such as the CD4094 IC, which has the push-pull output capability of the shift register) is used to store digital signals, adjust the amplitude of digital signals according to the input voltage, and transmit digital signals to each driver circuit unit in sequence according to the timing.

[0032] The driving circuit unit is used to convert the input digital signal into an electrical signal, control the pixel state on the electronic paper based on the field effect, and adjust the refresh frequency according to the amplitude of the electrical signal.

[0033] In electronic paper display technology, an adjustable boost circuit is a key component, dynamically adjusting the output voltage according to load requirements. This is achieved through precise control of pulse width or other strategies to regulate the voltage level applied to the electronic paper, thereby affecting the movement speed and orientation of microcapsules. Electronic paper relies on precise control of the direction and duration of the voltage in each color channel to change colors and update images. Increasing the voltage speeds up the microcapsule response, thus accelerating screen content updates; conversely, decreasing the voltage slows down the refresh rate, making it suitable for displaying static content.

[0034] Furthermore, the adjustable boost circuit enhances the system's flexibility, meeting the needs of different application scenarios. For example, fast refresh rates are not required when displaying static text, while higher refresh rates are needed to ensure smoothness when playing animations or performing interactive operations. By flexibly adjusting the output voltage, not only can the refresh rate be optimized, but power consumption can also be effectively managed, extending device uptime. Therefore, this circuit not only improves the performance of e-paper but also enhances its adaptability and practicality.

[0035] On the other hand, due to the limited number of I / O interfaces of the MCU, this invention employs a shift register to simplify the control logic and optimize input / output. The shift register can receive serial data from the MCU and convert it into parallel output, allowing more electronic paper display channels to be controlled with fewer I / O interfaces. This significantly reduces the complexity of the hardware design and solves the problem of insufficient I / O pins when multiple channels need to be controlled independently. Furthermore, the shift register supports cascading, further expanding the control capabilities and providing precise control even for large-size or high-resolution displays. This design not only improves the system's flexibility and scalability but also reduces cost and power consumption, ensuring stable operation of the electronic paper in various application environments, handling everything from simple text display to complex image updates with ease. In conclusion, the shift register, with its efficient serial-to-parallel conversion function, becomes an important component of the electronic paper driving system, achieving efficient and flexible control.

[0036] As for the final driving method of electronic paper, this invention uses a push-pull circuit consisting of two field-effect transistors (FETs) for each channel. The upper FET is a P-type FET, and the lower FET is an N-type FET, providing bidirectional driving capability for each channel.

[0037] This push-pull circuit configuration allows each channel to provide bidirectional drive capability, meaning it can apply either a positive or negative voltage to the load. In electronic paper, this helps to precisely control the direction and speed of movement of the microcapsules, as the display principle relies on precise control of the voltage direction and timing for the corresponding channel of each color block.

[0038] Simultaneously, it allows for a low on-resistance (Rds(on)) in the on-state, meaning lower energy loss and higher efficiency. This is particularly important for low-power applications, such as electronic paper displays, as it helps extend device runtime and reduce heat generation. Furthermore, through the coordinated operation of the two MOSFETs, the push-pull circuit can provide higher output current when needed, ensuring sufficient drive capability to quickly respond to the movement demands of the microcapsules. This is especially crucial for dynamic content display, as high refresh rates are required in these scenarios to ensure smooth operation.

[0039] Furthermore, using field-effect transistors (FETs) as the output driving element is generally less expensive and easier to integrate compared to other types of transistors (such as bipolar transistors). In addition, the push-pull circuit's simple structure, strong driving capability, and fewer required components further reduce manufacturing costs. This is a significant advantage for low-cost, mass-produced electronic paper products.

[0040] Each channel can serve as a common terminal (e.g., CH1_IN is the signal input port, CH1_OUT is the signal output port, see...). Figure 2 The system can be controlled via a public terminal, and the number of public terminals can be increased or decreased according to actual needs. This flexibility simplifies system design and supports the application requirements of electronic paper displays of different sizes and resolutions.

[0041] Specifically, the circuit composition of a push-pull circuit is as follows: Figure 2 As shown, the source of the P-type field-effect transistor (Q2) is grounded (GND), and its gate is connected to a digital signal through a first resistor (R1); the source of the N-type field-effect transistor (Q1) is connected to the operating voltage (VCC), and its gate is connected to a digital signal through a first resistor (R1); the drain of the P-type field-effect transistor (Q2) is connected to the drain of the N-type field-effect transistor (Q1), and outputs a driving voltage to the color block corresponding to the current driving circuit unit in the electronic paper.

[0042] Therefore, using a push-pull circuit for driving not only improves the performance of electronic paper display systems, including more efficient energy conversion, stronger output current capability, and bidirectional driving capability, but also takes into account cost-effectiveness and design flexibility. These characteristics work together to ensure that electronic paper technology can operate stably in a variety of application scenarios, whether it is simple object skin color changing, text display, or complex image updates.

[0043] In addition, this utility model also includes an electronic paper display device, which uses the electronic paper driving circuit mentioned above to display electronic paper content.

[0044] In summary, the electronic paper driving circuit and display device described in this utility model, through optimized voltage regulation and pulse control technology, can significantly accelerate the movement speed of electrophoretic particles, thereby achieving faster screen refresh. This is particularly important for dynamic content display (such as animation and video playback), and can provide a smoother user experience.

[0045] Each channel uses a push-pull circuit structure composed of P-type and N-type field-effect transistors, which not only reduces costs but also ensures sufficient driving capability, making it suitable for low-cost, low-refresh-rate, and low-power applications.

[0046] By introducing partitioned drive technology, only the parts that need updating are refreshed, rather than the entire screen, which further improves the refresh rate and reduces unnecessary power consumption.

[0047] The number of common terminals can be increased or decreased as needed, giving the driver circuit good scalability and enabling it to adapt to electronic paper applications of different scales and complexities.

[0048] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0049] Furthermore, in this utility model, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0050] In this utility model, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0051] Furthermore, the technical solutions of the various embodiments of this utility model can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the protection scope claimed by this utility model.

Claims

1. An electronic paper driving circuit, characterized in that, include: An adjustable boost circuit is used to control the voltage of the input shift register; MCU is used to transmit digital signals with timing and direction control to shift registers; The shift register is used to store digital signals, adjust the amplitude of the digital signals according to the input voltage, and transmit the digital signals to each drive circuit unit in sequence according to the timing. The driving circuit unit is used to convert the input digital signal into an electrical signal, control the pixel state on the electronic paper based on the field effect, and adjust the refresh frequency according to the amplitude of the electrical signal.

2. The electronic paper driving circuit as described in claim 1, characterized in that, The adjustable boost circuit uses a boost converter to adjust the output voltage.

3. The electronic paper driving circuit as described in claim 1, characterized in that, The MCU used is based on the ARM Cortex-M core.

4. The electronic paper driving circuit as described in claim 1, characterized in that, The shift register uses a driver IC based on the SN74LVC16T245 model for synchronous serial input and parallel output of digital signals.

5. The electronic paper driving circuit as described in claim 1, characterized in that, When the MCU has sufficient I / O ports, each drive circuit unit is independently controlled by the MCU's I / O ports; when the MCU has insufficient I / O ports, each drive circuit unit is controlled by a cascaded serial-to-parallel converter using a shift register.

6. The electronic paper driving circuit as described in claim 1, characterized in that, The driving circuit units all employ push-pull circuits under field-effect control to drive the electronic paper.

7. The electronic paper driving circuit as described in claim 6, characterized in that, The push-pull circuit consists of two field-effect transistors, with the upper transistor being a P-type field-effect transistor and the lower transistor being an N-type field-effect transistor.

8. The electronic paper driving circuit as described in claim 7, characterized in that, The source of the P-type field-effect transistor is grounded, and the gate is connected to a digital signal through a first resistor; the source of the N-type field-effect transistor is connected to the operating voltage, and the gate is connected to a digital signal through a first resistor; the drain of the P-type field-effect transistor is connected to the drain of the N-type field-effect transistor, and outputs a driving voltage to the color block corresponding to the current driving circuit unit in the electronic paper.

9. The electronic paper driving circuit as described in claim 1, characterized in that, The electronic paper displays changes by controlling the movement of microcapsules inside the electronic paper through a drive circuit unit.

10. An electronic paper display device, characterized in that, Includes the electronic paper driving circuit as described in any one of claims 1 to 9.

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