SI21771A - Electromagnetic display drive system - Google Patents

Abstract

New technical solution of the electromagnetic display pixel driving system solves the problem of switching the display pixel flap between two stable "ON" and "OFF" positions. The magnetic circuit of the display pixel consists of a permanent magnet in the display pixel flap and an electro-magnet with a magnetic core. Said permanent magnet is made using an injection molding process and is divided in two areas with antiparallel direction of magnetization, which is also perpendicular to the flap's surface and pivoting axis. Electro-magnet is placed under the flap and has a preferably U shaped magnetic core, which is oriented parallel to the pivoting axis. This design minimizes the stray magnetic field and interactions between neighboring display pixels.

Description

The subject of the invention is the embodiment, materials used and the manufacturing process of a magnetic circuit of a magnetic switch used to drive the flap of a single point of the display.

TECHNICAL FIELD OF THE INVENTION

The present invention belongs to the group of bistable magnetic actuators, the operation of which is based on the interaction of the magnetic field of the permanent magnet of the display flap and the magnetic core of the electromagnet.

According to the International Patent Classification, the invention includes construction, selection of materials, process for manufacturing a magnetic switch and limiting the scattered magnetic field to the environment, and in its group H01F 3/14, H01F 7/14 and H01F 7/121 its use in group G09F 3 / 4 and G09F 9/37.

TECHNICAL PROBLEM SOLVED BY THE INVENTION

The present invention is a new technical solution of a magnetic switch for driving the hatch of the display with a simple, compact and inexpensive construction. A magnetic switch is essentially a bistable actuator, which must be able to switch from one bistable position to another with minimal energy consumption. This requires a specially designed magnetic circuit, which must be made of materials with well-defined magnetic properties. The magnetic circuit of the switch must also ensure a minimum spread of the magnetic field into the surroundings, preventing the adjacent points of the display from interacting. The switch must operate reliably over a wide temperature range and ensure the stability of the flap position in both bistable positions. To the extent that external influences such as vibrations, shocks, vibrations, etc., change the position of the display flap, the magnetic switch must immediately return the flap to its original position, ie a single position, once the external influence has been eliminated.

TECHNICAL SOLUTIONS Known So far

Electromagnetic display panels have been known for over two decades and play an important role in applications where a relatively large display with very contrasting inscription and excellent visibility under good light conditions is required. The bistable electromagnetic display panels (US 3,871,945, US 4,577,427, US 4,860,470, EP 0 084 959, EP 0 731 435 Al, US 4,243,978, US 5,771,616, US 6,272,778, US 6,025,825, US 5,898,418, US 6,603,458, ...) meet the above requirements. They are used to show the destination of the route or. bus and train routes, display boards at airports, bus and train stations and at sports fields. In good light conditions, these displays have good contrast and excellent lateral visibility. This is achieved by using a bright reflective color on the selected display elements and black matte plastic on the non-selected display elements.

The principle of operation of existing solutions is based mainly on a rotary flap that can be rotated about its axis by <180 ° between the mechanical rotary limiters and has the size of the entire display point. The flap is painted in high contrast colors on the front and back (EP 0327250, US 6,272,778, US 6,025,825, US 5,898,418, ...). To switch between the "on" and "off" positions of the point of view, these solutions typically use a permanent magnet integrated into the flap and a coil coiled around the point (EP 0327250, US 6,603,458, US 6,272,778, ...) or U shaped magnetic in the flap. sails (US 4,243,978, US 6,025,825, US 5,898,418, US 5,005,305, ...). Some technical solutions include an additional permanent magnet to improve the stability of both flap positions (US 4,243,978, US 4,531,318).

There is, however, another substantially different mode of operation based on a point of view divided into two parts. Each point has a built-in bistable rotary damper that is asymmetrical with respect to the rotary axis. In each of the bistable positions, the flap covers one of the two parts of the display point. The side of the flap facing the point and the surface of the point flap covered by the flap are painted in one color, and the opposite side of the flap and the rest of the surface of the dot with the second color contrasting the first with very contrast (US 6,603,458, DE 3501912C2, DE 3601018A1). To switch between the "on" and "off" state of the point, this solution uses a permanent magnet embedded in each flap near the rotary axis. The flap rotates from one stable position to the other an electromagnet having a flat magnetic core located at the back of each display point. Such a construction has the advantage, over other solutions, that the whole structure can be significantly thinner (only half of the point surface rotates about an axis)

DESCRIPTION OF THE INVENTION

The key purpose of the invention is to increase the performance and reliability of the operation of the electromagnetic drive system for changing the position of the display flap between the "ON" and "OFF" position of each display point with minimum electricity consumption, to increase the stability of the flap position in both bistable positions, to reduce the magnetic interactions of neighboring points to increase the compactness of the magnetic switch design with a reduced number of components, the possibility of automatic assembly and low cost of construction of the display, and to reduce the thickness of the display.

The essence of the magnetic switch according to the invention is in the form of a magnetic circuit which applies torque to the hatch of the display in two locally separated areas according to claim 1. With two areas of the session, the total force acting on the hatch is increased.

In the invention, the proposed solution is implemented with the U-shaped electromagnet core and the magnet or magnets on the flap. In this case, the core 3u (Fig. 1) is positioned longitudinally on the axis of rotation of the flap, which is not the case in other technical solutions that use the U-shaped core of the electromagnet. Such a kernel position provides less influence of the flap position on torque than is the case with the technical solutions of the aforementioned patents and also reduces the thickness of the display using the U-shaped kernel. The magnet on the flap can be in one piece with antiparallel laughing magnetization, which is also perpendicular to the surface of the flap and the axis of rotation of the flap, or it can be divided into two separate parts which are also antiparallel magnet. The magnets are made of plastic bonded NdFeB powders or of plastic bonded ferrite powder by a two-component injection molding process.

The magnetic circuit of the switch is dimensioned with deliberately selected materials using the finite element method so that minimal energy is required for switching. The capacity of the magnetic switch, the reliability of operation and the stability of the positions of the flap in bistable positions are guaranteed by the magnitude of the torque of the flap. In the invention, the reduction of magnetic influences between adjacent points is achieved by the design of a magnetic circuit that provides a minimum spread of the magnetic field. As a result, there is no need for alternating orientation of the flaps of adjacent points, such as in US 6,603,458.

DESCRIPTION OF THE IMAGES

Hereinafter, the invention is exemplified and illustrated by way of figures showing:

FIG. 1. - Magnetic magnetic switch system with U-shaped electromagnet (3u + 5), comprising:

• Rotating flap 2 with integrated magnets (NdFeB plastomagnet or plastoferrite) 2ci, 2c ₂ and 2d rotation axis; The surfaces of the flap 2a and 2b are painted in very contrasting colors, • solenoid coil 5 • U-shaped magnetic core 3u

FIG. 2. - Display segment structure with built-in magnetic switch.

FIG. 3. - Explosion of the magnetic field into the vicinity of the magnetic switch.

• Fig. 3a - Computer simulation of magnetic conditions in the stable position of the flap at the U core.

• Fig. 3b - Computer simulation of magnetic conditions in unstable flap position at U core.

• Fig. 3c - Computer simulation of magnetic conditions in the stable position of the flap at a straight (rod) core.

• Fig. 3b - Computer simulation of magnetic conditions in an unstable flap position at a straight (rod) core.

FIG. 4. - Set of display flaps after injection molding.

DETAILED DESCRIPTION OF THE INVENTION

The electromagnetic drive system of the display according to the invention is described in detail by means of Figures 1-4

The magnetic switch for changing the position of the display flap between the "ON" and "OFF" states of a single point according to the invention is characterized in that the electromagnet U is in the form of a nucleus positioned in the direction of the axis of rotation of the flap and that the orientation of the magnets on the flaps is identical at all points of the display.

As can be seen from FIG. 1, the magnetic switching system is constructed of flap 2 and an electromagnet.

A permanent magnet is built into the switch flap, which is divided into two areas 2ci and 2c ₂ by the magnetization direction. The magnetization directions of the first and second regions are antiparallel and at the same time perpendicular to the axis of rotation of the flap 2d and to the surface of the flap. The magnet on flap 2 can also be divided into two separate segments 2ci and 2c ₂ , as shown in the example in FIG. 1. The system shown in this figure consists of a flap 2 with two permanent magnets and an electromagnet (3u + 5). In this case, the direction of magnetization of the segments is the same as before for the areas. Solid magnet materials based on plastically bonded NdFeB powders or plastically bonded ferrites (plastoferites) are used to make magnets. The display flap is manufactured using a two-stage injection molding process. In the first stage, a magnet is injected and in the second stage, the rest of the flap volume is plastic. The magnet is ejected in the presence of a magnetic field, which creates anisotropy of the magnetic properties and thus better magnetic properties in the direction of the field, which increases the magnetic flux density and, consequently, the flap torque. In this way, sufficient torque of the flap is achieved even with the use of plastic bonded rigid magnetic materials which have poorer magnetic properties than sintered materials. In the case of plastoferrite magnetization, magnetization is performed with permanent rare earth magnets and, in the case of coupled NdFeB, with a specially designed current loop, which is powered by a current pulse. The magnetization is performed simultaneously for all the flaps connected to the set (see Fig. 4). The magnets of all the flaps of the display are magnetically equally oriented, which significantly simplifies production and facilitates production automation. Thereafter, the solution of the invention also differs from the rod-core solution, such as US 6,603,458.

The solenoid is constructed of solenoid coil 5 and magnetic core 3u. It is mounted below the flap axis, as can be seen from FIG. 1 and FIG. 2 such that the magnetic core is aligned with the axis of the flap. Such a kernel position provides less influence of the hatch position on the torque than in the case of technical solutions with the kernel cross position on the hatch axis.

The solenoid coil is wound on a plastic coil that is part of the display frame only (Fig. 2), which is part of monolithic block 1 and forms several display points. The ends of the winding are soldered to the terminal pins 4a and 4b, which are inserted into the display frame lc and ld.

The magnetic core 3u has a U shape and is made of a magnetically solid semi-rigid material, which has satisfactory magnetic properties by thermal treatment after mechanical treatment. One arm of the core is inserted into the hole of the coil 5 and the other is located in the groove of the frame of display 1, which fixes its position. The u-shaped kernel allows the display to be thinner than is possible with a stick core.

The magnetic circuit of the switch, consisting of the magnetic core of the electromagnet, the magnets on the flap and the air gap between the core and the magnets, is designed and optimized using the 3D finite element method and is adapted to the magnetic properties of the materials used. The magnetic field representation for the two extreme positions of the flap is given in Figs. 3.

The object of the invention is also characterized by two fields of action of magnetic force on the hatch of the display, which generate torque. As a result, the momentum increases and is further increased due to the increase in the magnetic flux density in the space between the magnetic core and the magnets on the flap, which is due to the U-shape of the nucleus, in which the magnetic field scattering is smaller (Fig. 3). rod-shaped. This makes it possible to produce larger display points. Increasing the torque also increases the stability of the display flap in the desired "ON" or "OFF" position. Due to the reduced scattering of the magnetic field, the mutual magnetic influence of adjacent points of the display is also reduced, which enables the same orientation of the flap magnets of all points of the display.

The flap position is changed by a current pulse through the coil 5 of the solenoid whose core is magnetized every time the flap position is changed. This makes the initially stable position of the flap unstable, causing the flap to flip into the opposite position, which has become stable due to the magnetization of the coil core. In this way, the stability of the new flap position is achieved even after the electromagnet coil current pulse is completed.

EXAMPLE

An electromagnetic display panel typically consists of a number of predominantly square display points assembled into a display array. Due to the large number of display points, a conventional manufacturing concept based on mounting parts of a single point directly to the printed circuit board of the display panel proves to be a complex and expensive process. To reduce costs and simplify production, 7 display points are combined into a monolithic block, which is the basic element for creating a display array. Monolithic block 1 (S1.2) is made of black matte plastic on a plastic injection molding machine. After injection, the block is painted with a contrasting color on the surfaces. Then insert the electrical contacts 4a and 4b into the lc and ld bearings. The next operation is winding 7 coils onto monolithic block 1 and soldering the winding ends to the connecting pins. This is followed by testing the ohmic resistance of the winding.

The 3u magnetic core is U-shaped and is made of a cylindrical rod of semi-solid magnetic material, which obtains the required magnetic properties after proper thermal treatment. One arm of the core is inserted into coil 5 and the other arm is inserted into block 1 to position it. The ends of the two arms of the core lie below the rotational axis of the flap 2 and are oriented parallel to said axis.

Rotary flaps 2 are manufactured separately. Since the flaps must have permanent magnets 2ci and 2c ₂ installed, the flaps are manufactured by a two-component injection molding process. Just like monolithic block 1, we paint one surface of flap 2a with the same bright fluorescent color while the other side of flap 2b remains unpainted - black matt plastic.

The permanent magnet on the flap consists of two segments 2ci and 2c ₂ . The magnetic field of these segments is oriented antiparallel and at the same time perpendicular to the rotational axis 2d and to the surface of the flap. The magnets are made of plastic bonded NdFeB material or plastic bonded ferrite material. The flaps are produced by a two-component injection molding process, with magnets first made and then the rest of the flap space filled with plastic. The magnet is injected in the presence of a magnetic field, which creates the anisotropic magnetic properties of the magnets, increases the magnetic flux density, and consequently increases the magnetic moment. With this fabrication process, sufficient magnetic moment on the flap is obtained despite the use of plastic bonded hard magnetic material which has worse magnetic properties than sintered magnets. The magnetically bonded plastic ferrite is made with permanent earth permanent magnets that are integrated into the injection molding tool. In the case of the use of plastic-bonded NdFeB magnets, magnetization is performed with a specially designed current loop built into the short-pulse high-current injection molding tool. The magnetization of plastic bonded ferrite magnets was performed simultaneously for all 14 flaps in the grid (S1.4). All the flaps in the display have the same magnetic orientation as opposed to the US 6,603458 flat magnetic core solution. This greatly simplifies production and facilitates the automation of the manufacturing process.

To achieve the most economical fabrication, 14 flaps are made simultaneously in two rows of 7 flaps (see Fig. 4), which are connected to the grid by spacers 19 and are spaced exactly as far apart as the remote axes lf and lg on the monolithic block 1 , gives an optimized process for the final assembly of the flaps. Just like monolithic block 1, we paint one surface of flap 2a with the same bright fluorescent color while the other side of flap 2b remains unpainted black matte plastic. After painting the flaps in the grid, cut off spacers 19 and insert two rows of 7 flaps 2 simultaneously into the bearings lf and lg of 14 rotary axes on two blocks 1.

Claims (10)

PATENT REQUIREMENTS A magnetic system for switching the flap of an electromagnetic display point consisting of a rotary flap (2) with two bistable positions and an electromagnet (5 + 3u) with a magnetic core (3u) and a coil (5) switching the flap (2) from one bistable position to another with a current pulse, the flap having a magnet (2c) and an electromagnet (5 + 3u) embedded under the flap (2), characterized in that the magnetic core (3u) is formed such that magnetic force or. magnetic moment created simultaneously in two separate areas of the flap (2). Magnetic display point flap switching system according to claim 1, characterized in that the magnet (2c) in the swivel flap is divided into two regions or is made up of two separate segments (2ci and 202), and that the two regions are or segment magnetized antiparallel and perpendicular to the flap surface (2a, 2b) and perpendicular to the flap axis (2d). Magnetic display point flap switching system according to claim 2, characterized in that the magnet (2c) is mounted close to the rotary axis (2d) and the segments (2ci and 2c ₂ ) are rectangular in shape or% roll shape. Magnetic display point flap switching system according to any one of claims 1 to 3, characterized in that the magnetic core (3u) is U-shaped and is arranged parallel to the rotary axis (2d). Electromagnetic display panel with a plurality of display points having a magnetic system according to any one of claims 1 to 4, characterized in that the magnets (2c) are integrated into the display panel flaps in all flaps oriented in the same way. 6. A process for manufacturing a magnetic switching system for an electromagnetic display point according to claims 1 to 5, characterized in that a magnet (2c) is built into the flap by the injection molding process of a plastic bonded solid magnetic material and that a strong magnetic is present in the injection process. field that gives anisotropic properties to plastic bonded magnets (2c). 7. A process for manufacturing a magnetic shutter flap switching system according to claim 6, characterized in that the magnet (2c) is made of plastic bonded ferrite material and is magnetized by primed rare earth magnets incorporated in the injection molding tool . 8. The process of manufacturing a magnetic shutter flap switching system according to claim 6, characterized in that the magnet (2c) is made of plastic-bonded NdFeB material and that it is magnetized by a specially designed current loop incorporated into the injection tool and that a current pulse is provided. used during the injection process as long as the plastic magnet binder is still soft. 9. The process of manufacturing a magnetic shutter flap switching system according to one of claims 1 to 8, characterized in that the winding of the coil (5) is wound directly onto the plastic monolithic block and that the ends of the winding wire are connected to the connecting pins (4a, 4b) ), which are inserted into the beds (lc, ld) on said monolithic block (1). 10. The process of manufacturing a magnetic shutter flap switching system according to any one of claims 1 to 9, characterized in that the magnetic field scattering and the interaction of adjacent points is minimal.