A multi-layer push-pull rod driven electromagnetic Braille dot display device

Abstract

A multi-layer push-pull rod driven electromagnetic braille display device includes a main body module, an ejector pin, a cover plate, a push-pull rod and an actuator. For a six-dot braille display device, the main body module is composed of three layers of flat plates with horizontal and vertical cross holes stacked together. For an eight-dot braille display device, the main body module is composed of four layers of flat plates. When the push-pull rod is pushed inward in the push-pull rod mounting hole, when the ejector pin reaches the upper dead point, the upper end of the ejector pin's head is higher than the upper plane of the cover plate, forming a "convex point" of the braille character; when the push-pull rod is pulled outward in the push-pull rod mounting hole, until the lower edge of the annular flange of the ejector pin contacts the upper surface of the main body module, the ejector pin is at the lower dead point, and the ejector pin's head is flush with the upper plane of the cover plate, forming a "flat point" of the braille character. The present invention provides a multi-layer push-pull rod driven electromagnetic braille display device, which is suitable for generating braille characters in all languages ​​and in all forms.

Description

Technical Field

[0001] The invention relates to the technical fields of mechanical engineering and electronic engineering, and in particular to a multi-layer push-pull rod driven electromagnetic braille dot display device. Background Art

[0002] According to the statistics of the World Health Organization (WHO), there are about 39 million blind people in the world, and the number is increasing year by year. There are more than 6 million blind people in China. For such a large and important group of blind people, the society needs to give them care and support, and they also urgently need a good learning environment and cultural education.

[0003] Blind people cannot learn and read like normal people. Their reading methods include auditory reading and touch reading. Tactile reading that relies on the sense of touch with fingers has the advantages of fast reading speed and good information discrimination. It is a must-teach course in blind schools. It is also one of the skills that blind people must master in order to communicate with the outside world and interact with others. It is the main way for blind people to acquire knowledge and information at this stage.

[0004] However, the number of blind people who can master Braille is very small, mainly because the carriers of Braille are limited, and learning places and learning tools are not popular. For example, Braille books are the main publications for blind people to appreciate and read, but there are few in number, the production cycle is long, the special paper is expensive, the process is complicated and the price is high, the information is delayed, the amount of information is small, the volume is bulky, and it is extremely inconvenient to carry. With the progress of society and the development of science and technology, improving the convenience of reading and learning for the blind has been increasingly valued by developed countries in the world, and various reading devices for the blind have continued to appear.

[0005] Braille is a text character designed for the blind to read and write. Braille books and Braille reading devices are both carriers of Braille. The Braille characters commonly used by the world today were created in 1824 by Frenchman Louis Braille, who used a raised-dot Braille writing system. China also has a national Braille standard (GB / T15720—2008). Braille contact drive devices are an important component of Braille learning and reading machinery. Domestic and foreign researchers have developed Braille contact drive mechanisms with different drive forms based on different principles, mainly including piezoelectric ceramics, electrical stimulation, memory alloys, pneumatics, temperature control, electromagnetics, and other new materials.

[0006] Although domestic and foreign scholars have developed various driving forms of Braille display, the only Braille display driving mechanism that has been successfully applied is the piezoelectric ceramic type. Piezoelectric ceramic Braille display devices have low power consumption, fast refresh speed, light weight, and can provide greater support force, but there are also shortcomings: the production and processing technology is cumbersome, and the cost of parts manufacturing is high, which limits the popularity of piezoelectric ceramic Braille display devices, so researchers are more concerned about the research and development of electromagnetic Braille display devices. The current electromagnetic Braille display mainly uses the characteristics of electromagnetic coils that generate magnetic fields when energized and disappear when the electromagnetic field is turned off to drive the protrusions and descents of Braille contacts to form Braille characters. It has the advantages of fast refresh frequency, high reliability, favorable price, easy manufacturing and maintenance, and can provide greater support force. However, the entire device has a large current demand, high power consumption, and requires the installation of a cooling device. It is large in size and requires major improvements in the working principle and composition structure. Summary of the invention

[0007] In order to overcome the shortcomings of the existing Braille contact driving mechanism, the present invention provides a multi-layer push-pull rod driven electromagnetic Braille display device, which is suitable for generating Braille characters in all languages ​​and in all forms.

[0008] The technical solution adopted by the present invention to solve its technical problem is:

[0009] A multi-layer push-pull rod driven electromagnetic braille display device, comprising a main body module, an ejector pin, a cover plate, a push-pull rod and an actuator, wherein the cover plate is arranged above the main body module and is detachably connected to the main body module. For a six-dot braille display device, the main body module is composed of three layers of flat plates with vertically intersecting holes stacked together, each layer of flat plates is provided with vertical holes in three rows and multiple columns, penetrating up and down, and after the three layers of flat plates are stacked together, the vertical holes are aligned with the center line to form an ejector pin mounting hole for installing the ejector pin; for an eight-dot braille display device, the main body module is composed of four layers of flat plates, each layer of flat plates is provided with vertical holes in four rows and multiple columns, penetrating up and down, and after the four layers of flat plates are stacked together, the vertical holes are aligned with the center line to form an ejector pin mounting hole; a row of horizontal holes is arranged on the side of each layer of flat plates in the front-to-back direction, which are push-pull rod mounting holes for installing the push-pull rod, the center line of the push-pull rod mounting hole is vertically intersected with the center line of the ejector pin mounting hole in the column, and each push-pull rod mounting hole is communicated with the corresponding ejector pin mounting hole respectively;

[0010] The middle part of the cover plate is provided with stepped holes with the same number of holes as the ejector mounting holes, which are thin at the top and thick at the bottom. Each stepped hole is coaxially opposite to the corresponding ejector mounting hole. The number of ejectors is the same as the number of ejector mounting holes and they are installed in the corresponding ejector mounting holes and stepped holes in a one-to-one correspondence. Each ejector is fitted with the ejector mounting hole and the stepped hole in a clearance. The ejectors are respectively installed into the ejector mounting holes from the upper part of the main module, and are seated on the upper surface of the main module by the annular flange of the ejector itself and its own gravity. Under each row of ejectors, there are push-pull rods with the same number as the ejectors in the row.

[0011] The push-pull rod comprises a curved surface profile for the ejector to be at the lower dead point and driving the ejector to move from the lower dead point to the upper dead point, and a rod body for the ejector to be at the upper dead point and matching with the push-pull rod mounting hole, and the bottom of each ejector is always in contact with the corresponding push-pull rod; the push-pull rod under each ejector can be installed in the corresponding push-pull rod mounting hole so as to move forward and backward, each push-pull rod is driven by an actuator, and each push-pull rod uniquely controls the lifting and lowering movement of a corresponding ejector;

[0012] The actuator is used to generate thrust and pull on the push-pull rod. The push-pull rod can move forward and backward in the push-pull rod mounting hole under the action of the actuator. When the push-pull rod is pushed inward in the push-pull rod mounting hole, the bottom of the ejector pin is gradually lifted by the push-pull rod. When the ejector pin reaches the upper dead point, the upper end of the head of the ejector pin is higher than the upper plane of the cover plate, forming a "convex point" of the Braille character; when the push-pull rod is pulled outward in the push-pull rod mounting hole, the ejector pin moves downward along the ejector pin mounting hole under the action of its own gravity until the lower edge of the annular flange of the ejector pin contacts the upper surface of the main module. At this time, the ejector pin is at the lower dead point, and the head of the ejector pin is flush with the upper plane of the cover plate, forming a "flat point" of the Braille character; the lift of the ejector pin, that is, the distance between the upper and lower dead points of the ejector pin, is the "convex point" height of the Braille character.

[0013] Furthermore, the ejector pin is composed of a head constituting a contact, an annular flange for positioning, a cylindrical shaft and a hemispherical bottom. The annular flange is arranged in the middle of the cylindrical shaft. The ejector pin as a whole is a rotating body. The head of the ejector pin is located in the fine hole of the stepped hole of the cover plate, and a convex point of a Braille contact is generated when the head of the ejector pin is raised. The annular flange of the ejector pin is located in the coarse hole of the stepped hole. The thickness of the annular flange of the ejector pin is less than the height of the coarse hole, and the axial clearance is ensured to be greater than the required contact height. The lower part of the cylindrical shaft is inserted into the ejector pin mounting hole of the main module and is clearance-matched with the ejector pin mounting hole.

[0014] Furthermore, the push-pull rod installation holes on each flat plate of the main module are arranged in a row, and the push-pull rod installation holes on two adjacent flat plates are staggered.

[0015] Furthermore, the push-pull rod is a rotating body as a whole, and the push-pull rod is arranged on the front and rear sides of each flat plate. Each push-pull rod can be independently pushed and pulled forward and backward in the corresponding push-pull rod installation hole. The push-pull rod includes two structures. The first push-pull rod is composed of a trapezoidal frustum, a cylindrical rod body, an annular flange and a tail with a circular hole at one end. The second push-pull rod is composed of a trapezoidal frustum, a cylindrical rod body and an annular flange. The center hole of the annular flange of this structure is the circular hole for installing the permanent magnet.

[0016] When the push-pull rod is pushed along the push-pull rod mounting hole, the side surface of the trapezoidal cone contacts the bottom of the ejector pin and gradually pushes the ejector pin up until the annular flange of the push-pull rod contacts the side surface of the flat plate. The bottom of the ejector pin is completely on the cylindrical rod body of the push-pull rod, and the ejector pin is at the top dead center, with a "convex dot" of Braille appearing on the cover plate. When the push-pull rod is pulled out along the push-pull rod mounting hole, the bottom of the ejector pin descends along the side surface of the trapezoidal cone until it is separated from the trapezoidal cone. The ejector pin sits on the main module by relying on its own annular flange. The ejector pin is at the bottom dead center, and the head of the ejector pin is flush with the upper surface of the cover plate, forming a "flat dot" of Braille.

[0017] Furthermore, both the flat plate and the cover plate are provided with positioning pin holes, and the positioning pin holes of the two correspond to each other up and down, and the cover plate and the main body module are fixedly connected together through the interference fit between the positioning pins and the positioning pin holes.

[0018] Furthermore, the actuator includes a permanent magnet, a solenoid and a cylindrical core shaft, the solenoid is sleeved on the cylindrical core shaft and fixed to it with heat-resistant glue; for the first push-pull rod, the permanent magnet is installed in the circular hole at the tail of the push-pull rod and is inserted into the solenoid along with the tail of the push-pull rod. When the push-pull rod is pulled out, the push-pull rod itself is limited by the annular flange. The cylindrical core shaft is installed on the bracket, and a small gap is retained between the end of the cylindrical core shaft and the end face of the permanent magnet to ensure that the cylindrical core shaft is magnetized by the internal magnetic field of the solenoid but not by the permanent magnet; for the second push-pull rod, the permanent magnet is installed in the circular hole of the annular flange, the annular flange is located outside the solenoid and corresponds to the cylindrical core shaft in the solenoid, and the cylindrical core shaft and the permanent magnet are at least kept at a non-magnetized distance.

[0019] Furthermore, a magnetic conductor is arranged in the gap between the solenoids. The magnetic conductor is installed on the bracket together with the cylindrical core shaft. The cylindrical core shaft, the bracket and the magnetic conductor constitute a magnetic circuit, which increases the magnetic field strength inside the solenoid.

[0020] Furthermore, each bracket is provided with a wiring board on the upper and lower sides respectively, and threaded holes are opened on the upper and lower parts of each bracket to fix the wiring board with screws, and the wire ends of the solenoid are welded to the wiring board.

[0021] Furthermore, the solenoid is in the form of a frame, the frame is hollow and has flanges at both ends, the solenoid body is wound around the frame, and when the push-pull rod is pulled out, the annular flange of the push-pull rod contacts the flange at the end of the frame, and the flange at the end of the frame acts as a limit for the push-pull rod;

[0022] The cylindrical mandrel is made of semi-hard magnetic material or moment magnetic material. After the cylindrical mandrel is inserted into the solenoid, the end of the mandrel is lower than the end face of the flange of the solenoid frame to ensure that the mandrel is not magnetized by the permanent magnet.

[0023] Furthermore, the cover plate is extended to the bracket at the front and rear ends, and threaded holes are arranged on the cover plate, and the bracket and the cover plate are connected together by screws.

[0024] The beneficial effects of the present invention are mainly manifested in that: when the solenoid is energized, the device realizes a push-pull action on the push-pull rod through the actuator, thereby driving the ejector pin to move up and down to form different arrays of Braille contacts; the solenoid is powered off after each refresh of the Braille array, and since the solenoid core shaft still maintains sufficient residual magnetism, it is ensured that the action of the push-pull rod driving the ejector pin remains unchanged, and the formed Braille contacts are mechanically and electromagnetically double locked; the main body module is composed of three layers of flat plates, each layer of the flat plate is relatively thin, which is convenient for installation and processing; the contact pin is seated in the ejector pin mounting hole on the main body module through the annular flange seat thereon, and the operation is more stable and convenient; the consumption is small, the cost is low, the refresh speed is fast, and it is easy to process and manufacture, so that the Braille reader or Braille dot display device is easy to be popularized and promoted, and has good social benefits and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural assembly diagram of a six-dot Braille display device in an embodiment.

[0026] Figure 2 It is a flat schematic diagram of the main modules of the six-dot Braille display device.

[0027] Figure 3 It is a schematic diagram of a cover plate of a six-dot Braille display device.

[0028] Figure 4 This is a structural diagram of the ejector pin.

[0029] Figure 5 It is a structural diagram of the push-pull rod.

[0030] Figure 6 This is another structural diagram of a push-pull rod.

[0031] Figure 7 It is a side view of the present invention.

[0032] Figure 8 It is a solenoid structure diagram.

[0033] Fig. 9 It is a schematic diagram of the cylindrical core shaft inside the solenoid.

[0034] Fig.10 It is a structural diagram of a magnetic conductor.

[0035] Fig.11 This is a structural diagram of the bracket. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings.

[0037] Reference Figures 1 to 11A multi-layer push-pull rod driven electromagnetic braille display device, the present invention is suitable for making both six-dot braille display devices and eight-dot braille display devices, including a main body module 1, a push-pull rod 2, a pin 3, a cover plate 4, and an actuator 5. For the six-dot braille display device, the main body module 1 is composed of three layers of flat plates with vertically intersecting holes stacked together, each flat plate 10 is provided with vertical holes in three rows and multiple columns, running through from top to bottom. After the three flat plates are stacked together, the vertical holes are aligned with the center line to form a pin mounting hole 101 for mounting the pin 3. A row of horizontal holes is arranged on the side of the flat plate in the front-to-back direction, which is a push-pull rod mounting hole 102 for mounting the push-pull rod 2, and the center line of the push-pull rod mounting hole 102 intersects vertically with the center line of the pin mounting hole 101. At the same time, each push-pull rod mounting hole is communicated with the corresponding ejector mounting hole; the ejector 3 is respectively installed into the ejector mounting hole 101 from the upper part of the main module 1, and the ejector 3 is seated on the upper surface of the main module 1 by its own gravity with its own annular flange 301, and the lower body 302 of the ejector 3 is in clearance fit with the ejector mounting hole 101. The middle part of the cover plate 4 is provided with the same number of stepped holes 401 with the same thickness as the ejector mounting holes, and the stepped holes are coaxially opposite to the ejector mounting holes. The flat plate 10 is provided with a positioning pin hole 103, and the cover plate is also provided with a corresponding positioning pin hole, and the cover plate 4 is fixedly connected to the main module 1 by the interference fit between the positioning pin and the positioning pin hole. The annular flange 301 of the ejector 3 is just placed in the coarse hole of the stepped hole 401 of the cover plate 4, and there is a margin for upward and downward movement. The actuator 5 is used to generate thrust and pull force on the push-pull rod 2. The push-pull rod 2 can move forward and backward in the push-pull rod mounting hole 102 under the action of the actuator 5. When the push-pull rod 2 is pushed inward in the push-pull rod mounting hole 102, the bottom 303 of the ejector 3 is gradually lifted by the push-pull rod 2. When the ejector 3 reaches the top dead center, the head 304 of the ejector is higher than the upper plane of the cover plate 4, forming a "convex point" 306 of the Braille character; when the push-pull rod 2 When the push-pull rod mounting hole 102 is pulled outward, the ejector pin 3 moves downward along the ejector mounting hole 101 under the action of its own gravity until the lower edge of the ejector ring flange 301 contacts the upper surface of the main module 1. At this time, the ejector pin 3 is at the lower dead point, and the head 304 of the ejector pin is flush with the upper plane of the cover plate 4, forming a "flat point" 305 of the Braille character; the lift of the ejector pin 3, that is, the distance between the upper and lower dead points of the ejector pin, is the "convex point" height of the Braille character.

[0038] Furthermore, for the eight-dot Braille display device, compared with the six-dot Braille display device, the main body module 1 has one more layer of flat plate 10, that is, it is composed of four layers of flat plates, and the upper and lower through holes of each layer of the flat plate are arranged in four rows and multiple columns, and the stepped holes 401 of the cover plate are also arranged in four rows and multiple columns, while the shapes of the ejector pin 3 and the push-pull rod 2, the structure of the actuator 5, and the working principle of the device are exactly the same.

[0039] The ejector pin 3 is composed of a head 304 constituting a contact, an annular flange 301 for positioning, a cylindrical shaft 302 and a hemispherical bottom 303. The ejector pin 3 is a rotating body as a whole, and is allowed to rotate in the mounting hole 101. The ejector pin head 304 is located in the fine hole of the stepped hole 401 of the cover plate 4, and generates a convex point of the Braille contact when it is raised. The ejector pin annular flange 301 is located in the coarse hole of the stepped hole 401. The thickness of the ejector pin annular flange 301 is less than the height of the coarse hole, and the axial clearance is ensured to be greater than the required contact height. The annular flange 301 also plays a limiting role in the lifting and lowering of the ejector pin, so that the ejector pin 3 does not fall from the ejector pin mounting hole 101 when the device is inverted. The lower part of the cylindrical shaft is inserted into the ejector pin mounting hole 101 of the main module 1 to play a guiding role. The bottom 303 of the ejector pin is hemispherical, so that when the ejector pin 3 rotates in the ejector pin mounting hole 101 , the ascending rule of the ejector pin 3 under the action of the push-pull rod 2 will not be changed.

[0040] The push-pull rod 2 that pushes the ejector 3 to rise is a rotating body as a whole, so as to allow rotation in the push-pull rod mounting hole 102. The push-pull rod 2 is arranged on the front and rear sides of each plate 10. Each push-pull rod 2 can be independently pushed and pulled forward and backward in the corresponding push-pull rod mounting hole 102. The push-pull rod 2 is composed of a trapezoidal frustum 201, a cylindrical rod body 202, an annular flange 203 and a tail 204 with a circular hole 205 at one end. When the push-pull rod 2 is pushed along the mounting hole 102, the side of the trapezoidal frustum 201 contacts the hemispherical body 303 at the bottom of the ejector and gradually pushes the ejector 3 upward. The push-pull rod 2 is pulled out along the mounting hole 102, and the hemispherical body of the bottom 303 of the ejector pin descends along the side surface of the trapezoidal cone 201 until it is separated from the trapezoidal cone 201. The ejector pin 3 is seated on the main module 1 by its annular flange 301. The ejector pin 3 is at the bottom dead center, and the head 304 of the ejector pin is flush with the upper surface of the cover plate 4, forming a "flat spot" in Braille.

[0041] The plate 10, cover plate 4, ejector pin 3 and push-pull rod 2 constituting the main body module 1 are all made of non-magnetic materials such as aluminum alloy, plastic, or stainless steel.

[0042] The function of the actuator 5 is to generate thrust or pull on the push-pull rod 2. The actuator 5 is composed of a permanent magnet, a solenoid 502, and a cylindrical core shaft 503. However, in order to achieve the same function of generating thrust or pull, there are two forms in terms of structural design. The first structural feature is that the permanent magnet is installed in the circular hole 205 of the push-pull rod tail 204, and is inserted into the solenoid 502 along with the push-pull rod tail 204. When the push-pull rod 2 is pulled out, the push-pull rod itself is limited by the annular flange 203. The cylindrical core shaft 503 is installed on the iron bracket 6, and the end of the core shaft 503 is in contact with the permanent magnet. A small gap is reserved at the end face to ensure that the cylindrical mandrel 503 is magnetized by the magnetic field inside the solenoid 502 but not by the permanent magnet. The solenoid 502 is mounted on the cylindrical mandrel 503 and fixed to it with heat-resistant glue. The second structural feature is that the push-pull rod 2 removes the tail 204, the permanent magnet mounting hole is opened in the annular flange 203, and is located outside the solenoid 502 and corresponds to the cylindrical mandrel 503 inside the solenoid, and the mandrel 503 and the permanent magnet are at least kept at a non-magnetized distance, and the solenoid 502 is mounted on the cylindrical mandrel 503 and fixed to it with heat-resistant glue. The working principle of the actuator 5 is that when the solenoid coil magnetic field is reversed under the action of positive and reverse currents, it interacts with the permanent magnet, thereby generating thrust or pull on the push-pull rod.

[0043] Furthermore, the push-pull rod mounting holes 102 on each flat plate of the main body module 1 are arranged in a row, but the push-pull rod mounting holes on two adjacent flat plates are staggered to save space.

[0044] Furthermore, the head 304 of the ejector pin 3 is a hemisphere or a parabolic rotating surface, which is convenient for blind people to touch with their fingers; the bottom 303 of the ejector pin 3 can also be of other shapes that are convenient for matching with the trapezoidal cone 201 at the end of the push-pull rod.

[0045] Furthermore, the solenoid 502 is in the form of a skeleton, and a skeleton center hole 506 is provided on the skeleton 504, and flanges 505 are provided at both ends. The skeleton 504 supports the solenoid, and when the push-pull rod 2 is pulled out, the annular flange 203 of the push-pull rod contacts the flange 505 at the end of the skeleton, and the flange at the end of the skeleton limits the push-pull rod 2.

[0046] The cylindrical core shaft 503 of the solenoid is made of semi-hard magnetic material or moment magnetic material, so that the cylindrical core shaft 503 is magnetized when the solenoid 502 is powered on, and after the power is turned off, the cylindrical core shaft 503 still has a strong residual magnetism, and continues to maintain a thrust or pull force on the permanent magnet 501, playing a magnetic locking role on the push-pull rod 2. After the cylindrical core shaft 503 is inserted into the solenoid, the end of the core shaft is lower than the end face of the solenoid frame flange 505 to ensure that the cylindrical core shaft 503 is not magnetized by the permanent magnet.

[0047] Furthermore, a magnetizer 7 is provided in the gap between the solenoids, and the magnetizer 7 is mounted on the bracket 6 together with the solenoid core shaft 503. The cylindrical core shaft 503, the bracket 6, and the magnetizer 7 form a magnetic circuit, which increases the magnetic field strength inside the solenoid 502. The four sides of the magnetizer 7 are all inwardly concave arc-shaped concave surfaces.

[0048] Furthermore, the front and rear sides of the main module 1 are provided with brackets 6, which are made of iron material. In addition to installing the solenoid core shaft 503 and the magnet 7 on the side, the upper and lower parts of the brackets are also provided with threaded holes 603 for fixing the wiring board 8 with screws, and the wire ends of the solenoid 502 are welded to the wiring board 8. 601 is a hole for installing the cylindrical core shaft 503, and 602 is a hole for installing the magnet 7. The upper and lower holes on the side of the bracket are both 601, and the middle row is alternately arranged with holes 601 and holes 602.

[0049] Furthermore, the cover plate 4 extends to the bracket 6 at the front and rear, and threaded holes are provided on the cover plate 4, and a through hole is also provided on the terminal block 8. The bracket 6 and the cover plate 4 are fixed together by screws passing through the threaded holes on the cover plate and the through holes on the terminal block, so that the entire device is connected as a whole.

[0050] Since the ejector pin 3, the push-pull rod 2 and the actuator 5 of the device all work independently, a contact array consisting of "convex points" and "flat points" can be generated on the cover plate 4, and the contact array can realize the display of Braille according to the Braille coding rules of various countries. The present invention can display one "square" of Braille dot characters, and can also be expanded to realize the display of multiple "squares" or multiple "rows".

[0051] It should be noted that the two specific embodiments in this specification are merely illustrative descriptions of the present invention and are not intended to limit its protection scope. Any non-substantial changes or improvements are within the protection scope of the present invention.

Claims

1. A multi-layer push-pull rod driven electromagnetic Braille display device, characterized in that: It includes a main body module, an ejector pin, a cover plate, a push-pull rod and an actuator, wherein the cover plate is arranged above the main body module and is detachably connected to the main body module. For a six-dot braille display device, the main body module is composed of three layers of flat plates with vertically intersecting holes stacked together, each layer of flat plates is provided with vertical holes in three rows and multiple columns, penetrating up and down, and after the three layers of flat plates are stacked together, the vertical holes are aligned with the center line to form an ejector pin mounting hole for installing the ejector pin; for an eight-dot braille display device, the main body module is composed of four layers of flat plates, each layer of flat plates is provided with vertical holes in four rows and multiple columns, penetrating up and down, and after the four layers of flat plates are stacked together, the vertical holes are aligned with the center line to form an ejector pin mounting hole; a row of horizontal holes is arranged on the side of each layer of flat plates in the front-to-back direction, which is a push-pull rod mounting hole for installing the push-pull rod, and the center line of the push-pull rod mounting hole is vertically intersected with the center line of the ejector pin mounting hole in the column, and each push-pull rod mounting hole is communicated with the corresponding ejector pin mounting hole respectively; The middle part of the cover plate is provided with stepped holes with the same number of holes as the ejector mounting holes, which are thin at the top and thick at the bottom. Each stepped hole is coaxially opposite to the corresponding ejector mounting hole. The number of ejectors is the same as the number of ejector mounting holes and they are installed in the corresponding ejector mounting holes and stepped holes in a one-to-one correspondence. Each ejector is fitted with the ejector mounting hole and the stepped hole in a clearance. The ejectors are respectively installed into the ejector mounting holes from the upper part of the main module, and are seated on the upper surface of the main module by the annular flange of the ejector itself and its own gravity. Under each row of ejectors, there are push-pull rods with the same number as the ejectors in the row. The push-pull rod comprises a curved surface profile for the ejector to be at the lower dead point and driving the ejector to move from the lower dead point to the upper dead point, and a rod body for the ejector to be at the upper dead point and matching with the push-pull rod mounting hole, and the bottom of each ejector is always in contact with the corresponding push-pull rod; the push-pull rod under each ejector can be installed in the corresponding push-pull rod mounting hole so as to move forward and backward, each push-pull rod is driven by an actuator, and each push-pull rod uniquely controls the lifting and lowering movement of a corresponding ejector; The actuator is used to generate thrust and pull force on the push-pull rod. The push-pull rod can move forward and backward in the push-pull rod mounting hole under the action of the actuator. When the push-pull rod is pushed inward in the push-pull rod mounting hole, the bottom of the ejector pin is gradually lifted by the push-pull rod. When the ejector pin reaches the upper dead point, the upper end of the head of the ejector pin is higher than the upper plane of the cover plate, forming a "convex point" of the Braille character; when the push-pull rod is pulled outward in the push-pull rod mounting hole, the ejector pin moves downward along the ejector pin mounting hole under the action of its own gravity until the lower edge of the annular flange of the ejector pin contacts the upper surface of the main module. At this time, the ejector pin is at the lower dead point, and the head of the ejector pin is flush with the upper plane of the cover plate, forming a "flat point" of the Braille character; the lift of the ejector pin, that is, the distance between the upper and lower dead points of the ejector pin, is the height of the "convex point" of the Braille character; The ejector pin is composed of a head constituting a contact point, an annular flange having a positioning function, a cylindrical shaft and a hemispherical bottom.

2. A multi-layer push-pull rod driven electromagnetic Braille display device as claimed in claim 1, characterized in that: The push-pull rod installation holes on each flat plate of the main body module are arranged in a row, and the push-pull rod installation holes on two adjacent flat plates are arranged in a staggered manner.

3. A multi-layer push-pull rod driven electromagnetic Braille display device as claimed in claim 1 or 2, characterized in that: The push-pull rod is a rotating body as a whole, and is arranged on the front and rear sides of each flat plate. Each push-pull rod can be independently pushed and pulled forward and backward in the corresponding push-pull rod installation hole. The push-pull rod includes two structures. The first push-pull rod is composed of a trapezoidal frustum, a cylindrical rod body, an annular flange and a tail with a circular hole at one end. The second push-pull rod is composed of a trapezoidal frustum, a cylindrical rod body and an annular flange. The center hole of the annular flange of this structure is the circular hole for installing the permanent magnet. When the push-pull rod is pushed along the push-pull rod mounting hole, the side surface of the trapezoidal cone contacts the bottom of the ejector pin and gradually pushes the ejector pin up until the annular flange of the push-pull rod contacts the side surface of the flat plate. The bottom of the ejector pin is completely on the cylindrical rod body of the push-pull rod, and the ejector pin is at the top dead center, showing a "convex dot" of Braille on the cover plate. When the push-pull rod is pulled out along the push-pull rod mounting hole, the bottom of the ejector pin descends along the side surface of the trapezoidal cone until it is separated from the trapezoidal cone. The ejector pin relies on its own annular flange to sit on the main module. The ejector pin is at the bottom dead center, and the head of the ejector pin is flush with the upper surface of the cover plate, forming a "flat dot" of Braille.

4. A multi-layer push-pull rod driven electromagnetic Braille display device as claimed in claim 1 or 2, characterized in that: The flat plate and the cover plate are both provided with positioning pin holes, which correspond to each other up and down, and the cover plate and the main body module are fixedly connected together through the interference fit between the positioning pins and the positioning pin holes.

5. A multi-layer push-pull rod driven electromagnetic Braille display device as claimed in claim 3, characterized in that: The actuator includes a permanent magnet, a solenoid and a cylindrical core shaft, the solenoid is sleeved on the cylindrical core shaft and fixed to the solenoid with a heat-resistant adhesive; for the first push-pull rod, the permanent magnet is installed in the circular hole at the tail of the push-pull rod and is inserted into the solenoid along with the tail of the push-pull rod. When the push-pull rod is pulled out, the push-pull rod is limited by its own circular ring flange. The cylindrical core shaft is installed on the bracket, and a small gap is retained between the end of the cylindrical core shaft and the end face of the permanent magnet to ensure that the cylindrical core shaft is magnetized by the internal magnetic field of the solenoid but not by the permanent magnet; for the second push-pull rod, the permanent magnet is installed in the circular hole of the circular ring flange, the circular ring flange is located outside the solenoid and corresponds to the cylindrical core shaft in the solenoid, and the cylindrical core shaft and the permanent magnet are at least kept at a non-magnetized distance.

6. A multi-layer push-pull rod driven electromagnetic Braille display device as claimed in claim 5, characterized in that: A magnetic conductor is arranged in the gap between the solenoids. The magnetic conductor is installed on the bracket together with the cylindrical core shaft. The cylindrical core shaft, the bracket and the magnetic conductor form a magnetic circuit, which increases the magnetic field strength inside the solenoid.

7. A multi-layer push-pull rod driven electromagnetic Braille display device as claimed in claim 5 or 6, characterized in that: A wiring board is provided on the upper and lower sides of each bracket respectively. Threaded holes are opened on the upper and lower parts of each bracket to fix the wiring board with screws. The wire ends of the solenoid are welded on the wiring board.

8. A multi-layer push-pull rod driven electromagnetic Braille display device as claimed in claim 5 or 6, characterized in that: The solenoid is in the form of a frame, which is hollow and has flanges at both ends. The solenoid body is wound around the frame, and when the push-pull rod is pulled out, the annular flange of the push-pull rod contacts the flange at the end of the frame, and the flange at the end of the frame acts as a limit for the push-pull rod; The cylindrical mandrel is made of semi-hard magnetic material or moment magnetic material. After the cylindrical mandrel is inserted into the solenoid, the end of the mandrel is lower than the end face of the flange of the solenoid frame to ensure that the mandrel is not magnetized by the permanent magnet.

9. A multi-layer push-pull rod driven electromagnetic Braille display device as claimed in claim 7, characterized in that: The cover plate is extended to the bracket at the front and rear ends, and threaded holes are arranged on the cover plate, and the bracket and the cover plate are connected together by screws.

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