1 Introduction Visual persistence (POV) is a visual short stay. When the human eye views an object, the image of the object will become on the retina. Photoreceptive cells on the retina convert light signals into bioelectrical signals that are transmitted to the brain through the optic nerve. However, when the object is removed, the impression of the optic nerve on the object does not disappear immediately. Modern medicine has proven that the human eye does not disappear within 1/24 of a second after seeing an object. This phenomenon is called visual persistence and is also the inertia of the human eye. This inertia causes the human vision to overlap, making the object "smooth and moving". Therefore, when the static picture is continuously displayed in more than 24 frames per second, we will see a smooth continuous dynamic picture. Rotating line array LED display based on visual persistence refers to the use of the visual persistence effect of the human eye [1]. By mechanical scanning, a column of linear array LEDs emits a specific LED at a correct position to form a pattern. A display such as text. According to its mechanical structure, the rotating linear array LED display mainly has two basic types: circular [2~3] and cylindrical [4~5] (in addition to the spherical, funnel-shaped display, they are essentially cylindrical A special case of the display). 2.POV display principle 2.1 Circular display principle In the POV-based circular rotating line array LED display, 20 strip-type LEDs are integrated on one strip PCB board, hereinafter referred to as line array LED1. The PCB board with integrated LED rotates with the motor around one end. When it is rotated to a suitable angle, the appropriate LED can be illuminated to display the content to be displayed. The schematic diagram is shown in Figure 1, and where to illuminate which LEDs It should conform to the display principle of a circular LED screen. Figures 2 and 3 respectively describe the display principle of a circular pointer clock and a digital clock. In Fig. 2, Fig. 2(1) specifies 20 LEDs for displaying the number and distribution of the dial, time scale, hour hand, minute hand and second hand. It can be clearly seen that the innermost and outermost ones are used to display the inner and outer rings of the dial. From the inside to the outside, the first to the 9th are used to display the hour hand, the first to the 12th are used to display the minute hand, the first to the 15th are used to display the second hand, and the 17th to the 19th are used to display the time scale. Specifically, 3 lights indicate 12-point scale, 2 lights indicate 3, 6, and 9-point scales, and 1 light indicates the remaining time scale. In order to improve the readability of the clock by separating the hour hand from the scale, the 16th LED is always off. During each rotation of the line array LED, the corresponding LED is illuminated at the position shown and the current time is displayed by delay. The time shown in Figure 2 (2) is 03:40:00. Figure 3 depicts the principle of the circular LED display showing the number, that is, lighting the first, seventh, eleventh, fifteenth and 20th LEDs in the time of each rotation, lighting the next moment 1, 3~15 and 20 LEDs can display the number 3. In particular, the specific calculation of the initial start, delay time and character elapsed time is detailed in the following. 2.2 Cylindrical surface display principle The structure of the POV-based cylindrical surface rotating linear array LED display is shown in Figure 4. This design adds a vertical PCB board with 17 SMD LEDs on the basis of the circular LED display. Hereinafter, it is called Line Array LED2. Of course, in order to maintain the smoothness of the system rotation, we have added at the other end. Studs and the like balance the weight at both ends. When the line array LED2 rotates with the motor, it lights up a specific LED at a suitable position, and under the influence of the visual persistence, we can see various texts and graphics. In Figure 5, Figure 5 (0) specifies the corresponding function of 17 LEDs, that is, from top to bottom, the first to the 16th LEDs are display LEDs, and the 17th is the bottom edge LEDs; Figure 5 (1~8) describes The cylindrical surface type LED display screen displays the detailed process of the letter D, that is, according to the font data of the letter D, the 3rd, 13th and 17th LEDs are lit at the starting time in each rotation, and are respectively illuminated at the next moment. 3rd to 13th and 17th, 3rd, 13th and 17th, 3rd, 13th and 17th, 3rd, 13th and 17th, 4th, 12th and 17th, 5th to 11th and 17th and finally If it is not lit, the letter D can be displayed. 3. Rotating line array LED screen design 3.1 Mechanical structure The mechanical structure of the rotating linear array LED display is shown in Figure 6. The structure requires that the weight be evenly distributed on both sides of the motor rotating shaft. In this paper, the MCU, clock chip, line array LED, integrated infrared receiver and other devices are soldered on a pointer type circuit board, which can make the rotating circuit become an independent part. A motor shaft jack is drilled at one end of the board, the jack is semi-circular and the radius is equal to the motor shaft. The motor shaft is inserted therein to drive the pointer plate to rotate. 3.2 System Communication Settings In the design, the display content, display mode switching and current time settings are all realized by infrared wireless communication. In Fig. 6, the infrared integrated receiving head (HS0038) receives the intermittent pulse of the frequency of 38KHz emitted by the handheld remote controller, and the HS0038 amplifies and detects the received signal, and obtains the TTL encoded signal to directly decode the time and number of the single chip. The display or pointer shows three different control signals. 3.3 Starting position calibration The stability of the motor speed directly determines whether there is ghosting and floating shadow. However, it is impossible to make it completely unchanged. In this case, the error will accumulate and form a floating shadow. Therefore, the continuous correction of the starting position is an indispensable technique for making a rotating LED display without a stepper motor. The small electric steel particles placed at a fixed position are detected by the magnetoelectric sensor to continuously locate the starting position to eliminate the accumulation error. This article installs an infrared receiver tube on the pointer board. When the infrared light emitted by the paired infrared light-emitting diode (the infrared light-emitting diode is mounted on the motor casing and aligned with the receiving tube) is received, the reverse conduction causes a low level to trigger an external interruption. Each time the pointer board rotates, an interrupt signal is generated, which is called a "zero-crossing signal." The task of the external interrupt is to clear the rotation angle to eliminate the accumulation error. 3.4 system power supply design Since the single chip, the line array LED, etc. will rotate with the motor rotating at a high speed. Wired power supply is complex, unstable, and has security risks. In order to make the DS1302 power down, the DS1302 chip is powered by a common button battery and the line array LED is powered wirelessly. The wireless power supply technology transmits the electrical energy to the load wirelessly through the principle of electromagnetic induction. A wirelessly powered device is typically constructed of two separate coils, referred to as a primary coil and a secondary coil. But this requires alternating current on the primary coil. Therefore, this paper converts direct current into alternating current by means of brushes. The structure and circuit diagram of the wireless power supply are shown in Figure 8. In Fig. 8 (1), the commutator and the brush of the same specification as the motor are placed on the shaft. The fixed commutator is connected to the upper rotating portion. 4 Conclusion In this paper, the working principle of two types of linear array LED rotating clocks based on POV is studied in detail. On this basis, the hardware of the system is closely simulated by simulation software such as Multisim and proteus, and the program is written in C language. Finally, the analog hour hand clock of the circular LED display, the digital clock, and the static and dynamic display of the smile pattern, the pull-down display of the cylindrical LED display, the Chinese character display, the printed word effect display and three kinds of animation display are realized. At the same time, this paper also realizes simultaneous multi-mode collaborative display of two types of displays. The partial display results are shown in Figure 9. Product categories of Lithium Battery Charger, we are specialized in manufacturers from China,Lithium Battery Charger Supplier suppliers/factory, wholesale high-quality products of manufacturing, we have the perfect after-sales service and technical support. Look forward to your cooperation! Lithium Battery Charger Lithium Battery Charger,Bike Lithium Battery Charger,Bicycle Lithium Battery Charger,Lithium Motorcycle Battery Charger Changxing Deli Technology Co., Ltd. , https://www.delipowers.com