Apparatus for the rapid indication of visual information arranged in a mosaic system by means of magnetic indicating elements
United States Patent 3916403

Apparatus for the indication of visual information arranged in a mosaic system by means of magnetic indicating elements, at high speed, in which the iron cores of the controlling electromagnets of the magnetic indicating elements are formed partially or entirely of a hard magnetic material, the coercivity of which is adjusted to a value lower than the coercivity of the permanent magnet components indicating the information, so that the programming speed of the information can be rendered independent of the indicating times, thus ensuring a high speed indication.

Mandzsu, Jozsef (Budapest, HU)
Jagicza, Laszlo (Budapest, HU)
Jodal, Sandor (Budapest, HU)
Ducza, Lajos (Budapest, HU)
Avarosi, Laszlo (Budapest, HU)
Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
40/463, 116/204, 345/84
International Classes:
G09F11/06; G08B5/24; (IPC1-7): G09F9/32
Field of Search:
340/378R,324R,324M,336,373,376 40
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US Patent References:

Primary Examiner:
Caldwell, John W.
Assistant Examiner:
Curtis, Marshall M.
Attorney, Agent or Firm:
Young & Thompson
Having described our invention, we claim

1. In apparatus for the indication of visual information by means of magnetic indicating elements arranged in a mosaic system, comprising permanent magnet flip-members displaying the information on a base panel and electromagnets excitable in a bipolar manner to control the flip-members, the electromagnets having excitation coil means whose leads are connected to an electronic control unit by which bipolar signals for excitation of the coils are emitted; the improvement in which the electromagnets have iron cores consisting at least in part of a hard magnetic material having remanent magnetism the coercivity of which is smaller than the coercivity of said permanent magnetic flip-members, the permanent magnet flip-members having a smaller magnetic field strength than that required for the demagnetization of the iron core of the associated electromagnet in the operative condition.

2. Apparatus as claimed in claim 1, in which said permanent magnet flip-members are made at least in part of barium ferrite.

3. Apparatus as claimed in claim 1, said flip-members being in the form of flat flip-leaves pivotally mounted on the panel at one edge of each flip-leaf for pivotal movement about an axis parallel to the panel to occupy one of two rest positions against the panel.

The present invention relates to apparatus for the rapid indication of visual information arranged in a mosaic system by means of magnetic indicating elements.

The use of indicator elements arranged in a mosaic system is widespread for the visual indication of information. In outdoor units, apparatus employing incandescent bulbs is generally employed.

In indoor installations, such as, for example, for passenger information, apparatus operating with magnetic indicating elements, which do not consume any energy during the indicating time, has become popular. A system constructed from such indicating elements is described, for example, in Hungarian Pat. No. 155,121. In this system, the information is represented by permanent magnets or synthetic resin spheres surrounding these magnets, wherein one-half of the spheres is provided with a dark coating and the other half with a light-colored coating. The magnets or electromagnets arranged beside the spheres serve for control purposes. Although the system is simple in its structure, it has the disadvantage that the information, due to the great inertia of the indicating elements, appears only after a relatively long period of time has elapsed. Thus, the control and/or programming times require at least several hundred milliseconds.

Other apparatus is known in which the information is displayed by lightweight disks carrying different colors on their surfaces, to which permanent magnets are attached, the poles of which are disposed between excitable poles. Although this arrangement substantially reduces the control time periods, the stable indication of the information is prolonged, due to the fact that the excitation of the electromagnets must be maintained even after the discs have been turned, until the discs enter into their rest position.

Among the systems constructed with magnetic indicating elements, those employing flip-flop indicating elements can be considered the most modern. A magnetic flip-flop system is described in Hungarian Pat. No. 175,250 wherein the individual flip-leaves are semicircular and their surfaces are provided with different color coatings. The individual flip-leaves also carry a permanent-magnet member, the magnetic axis of which is at right angles to the plane of the respective leaf. The information is represented by the individual flip-leaves, together with the associated base panel.

With respect to the speed of operation, the system embodying flip-flop indicating elements is a great step forward, since only quite minor masses need be set in motion in order to make the information appear. The small masses make possible short control times. However, to achieve a stable position of the leaves, the electromagnets must be excited by the control pulses for a longer period of time than necessary for flipping over the individual flip-leaves.

In these systems, in case of indicating elements with diameters of, say, 15-20 mm., the minimum period of excitation of the electromagnets amounts to 50-60 milliseconds, considering the optimum excitation current strengths. This is a relatively short time period compared to the electromechanic indicating elements. However, in case of the larger mosaic-type indicating elements with diameters of 30-50 mm., this time period is considerably increased.

Hungarian Pat. No. 158,131 discloses flip-leaf indicating elements with larger dimensions, wherein the flip-leaves are no longer produced from a magnetic material, but rather from a nonmagnetic material. The movement of the leaves is still carried out by a shift in the center of gravity caused by mutual magnetic effect. In this latter system, even with its larger dimensions, a decreased time period of 50-60 milliseconds can be used with respect to the excitation of the electromagnet used for control purposes, since it is sufficient to excite the individual leaves only until the center of gravity has been shifted. This is so, because the shift in the center of gravity already ensures the stable fixation and stationary position of the individual flip-leaves.

The optimum control for apparatus operating in accordance with the magnetic principle, while achieving a minimum usage of cable connections, is an arrangement described in Hungarian Pat. No. 158,129, wherein an electromagnet is controlled in a bipolar manner by means of an excitation coil.

It will be evident from the above that an information system constructed with magnetic indicating elements with the use of the smallest number of cable lines makes it possible, with a corresponding multiplication of the control cable lines, to effect a selective choice and control of the excitation coils of the bipolarly excited electromagnets controlling the magnetic indicating elements, by providing ground connection points separated by means of diodes.

A feature common to all of the systems mentioned above is that the magnetic indicating elements are controlled by means of electromagnets wherein, in the interest of achieving a maximum magnetic force field with minimum energy, soft iron of high permeability is used as the iron core. The duration of excitation of the electromagnets can be reduced, in dependence on the mass of the movable elements, to 40-50 milliseconds. Although these excitation periods permit a write-out speed of 800-1,000 letters per minute, this speed still is far below that possible in view of the velocity of the circuit elements employed.

Accordingly, it is an object of this invention, while retaining the advantages of the aforementioned systems, to reduce the control time as far as possible to the minimum time determined by the circuit elements employed, independently of the duration of indication of the information and independently of the mechanical time constant, and thus to provide a high-speed indicating system, by means of which, with the use of mechanical indicating elements operating according to the magnetic principle, even movable images can be displayed.

It is also an object of the invention to provide such apparatus wherein the energy requirement, by very simple means, is reduced to a minimum, and the system can be utilized, in spite of its simplicity, for accomplishing very complicated tasks, such as, for example, for the display of movable images, as read-out equipment for electronic computers, etc.

To achieve these objects, the invention provides apparatus for the indication of visual information formed by means of magnetic indicating elements in accordance with the mosaic system, at high speed, comprising permanent-magnet members indicating the information directly or indirectly, as well as bipolar-excited electromagnets controlling the permanent-magnet members, wherein the leads of the excitation coils of the electromagnets are connected with multiplication to a conventional electronic control unit producing the bipolar control signals. The principal novelty of the apparatus is thaat the iron cores of the control magnets are formed partially or entirely of a hard magnetic material with remanent magnetism, the coercivity of which is smaller than the coercivity of the permanent magnets indicating the information directly or indirectly, the permanent magnets indicating the information directly or indirectly having a smaller magnetic field strength than that necessary for the demagnetization of the iron core of the controlling electromagnet in the operative condition.

The coercivity of the iron cores of the controlling electromagnets is adjusted by any of the known heat treatments for this purpose.

According to another embodiment of the device, the bipolar control output of the electronic control circuit for exciting the iron core of the controlling electromagnet ensures, in dependence on the information, a magnetizing level which exceeds the coercivity of the iron core either in the positive or in the negative magnetization direction.

According to still another embodiment, the permanent magnets indicating the information are made from a barium ferrite base material.

Also, the iron cores of the individual electromagnets can be associated with entirely separate coils, independent from one another and controllable in a bipolar manner.

A very great advantage of this invention is that, for indicating information, a pulse duration of only 1-1.5 milliseconds is required, which is substantially below the mechanical time constant of the indicating elements, wherein this time is determined essentially by the electric parameters, such as coil inductivity, the stray capacitance, etc. Thus, it is sufficient to excite the iron core during the magnetizing period up to a certain extent, i.e. to magnetize the same, and thereafter, the remanent magnetic field of the iron core executes the indication of the information due to the influence on each other by the permanent magnets.

Thus, for example, the process of covering a display panel with 100 letter fields from a storage means takes 0.1 to 0.15 seconds; and this produces the visual impression in an observer that the entire panel is displaying all the letters simultaneously, in a flash.

Another great advantage of the invention is that, in the case of a flip-flop indicating system, the shielding plates required between the individual mosaic elements can be omitted, since the danger of a mutual effect can be entirely eliminated, and the degree of operating safety is also increased to a great extent, even considering the mechanical factors which are not as reliable.

Other objects, features and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawing, in which:

FIG. 1 is a somewhat schematic view of an individual flip-leaf of the present invention and its position relative to the base panel, and the magnetic drive and control of the flip-leaf; and

FIG. 2 is a diagram on which the coercive field strength of the flip-leaf is compared with that of the associated iron core.

In the drawing, the flip-leaf 1 is shown which, apart from its electromagnetic relationships, can be of conventional construction, and is mounted for movement under the impetus of its associated iron core 2, between the two illustrated indicating positions relative to the base panel 3. The manner of indication of information on the flip-leaf 1 and the base panel 3, and the interaction of these elements relative to each other with respect to the display of information, may be entirely conventional. The coils of the iron core 2 are indicated at R1 and R2.

It will be understood that the electronic control circuit which delivers at its outputs the various positive and negative voltages, and the cable connections thereof with the FIG. 1 structure, may be entirely conventional, and hence are not illustrated.

The number of the information channels of the electronic control unit will coincide with the number of picture element columns of the indicator unit, which latter is constructed with a conventional homogeneous arrangement of picture elements, the columns being connected by means of cables.

The number of position-selection units and/or the outputs thereof, with which the electronic control unit is provided, coincides with the number of picture element lines of the indicator unit, which are likewise connected with one another by cables.

The combined control poles of the electromagnets controlling the picture elements, multiplied in the column direction, are connected to the column-type inputs of the indicator unit connected with the information channels, whereas the other poles of the excitation coils R1 and R2 of the above-mentioned control magnets are connected to the separate ground connection points of the line-wise multiplied and line-wise controllable position selection units by means of series connected elements, e.g., diodes, having the effect of valves in both directions.

In correspondence with the individual, selected lines, the outputs of the position selection unit of the electronic control circuit connect diode-separated ground connection points in accordance with the joining of the current paths, and the thus-connected ground connection points are connected to the ground connection point of the supply unit. The iron cores 2 of the electromagnets controlling the picture elements are magnetically coupled with the magnetic flip-leaves.

The flip-leaf 1, controlled by the magnetic coupling, assumes one of its two stable positions and simultaneously indicates the information by the color of its surfaces, together with the base panel 3, or obscures such information.

The mode of operation of the above-described system is as follows:

The electronic control unit applies, channel-wise, a positive or negative voltage to the inputs of the indicator unit, multiplied according to columns, in dependence on the programming and/or when derived from an information storage means, in dependence on the content of the storage means. Simultaneously with the read-out of the information, the line-wise position selection unit activates the corresponding picture element line, which can be set by the programming.

In the activated, that is, the selected line, the electromagnets controlling the individual picture elements are excited with positive or negative polarity. During the excitation period, e.g., during 1-1.5 milliseconds, the iron core 2 is fully magnetized and furthermore activates, as a permanent magnet, the flip-leaf 1 associated therewith by magnetic coupling. The flip-leaves turn their light or dark surfaces toward the observer, in dependence on the excitation or magnetization direction. Of course, the duration of the indication is thereafter dependent on the mechanical time constant.

However, after the 1 millisecond pulse, the subsequent line is immediately activated, so that, in effect, the display of the first line has not yet been terminated when the subsequent line is already being activated, and this process continues over the entire board.

By disposing, on the iron core of the electromagnet, two coils R1 and R2 which are likewise connected in the aforementioned manner with each other and/or with the column-scanning and line-determining channels of the electronic control unit, one of these coils can be employed for sensing the condition of the magnetic core, whereas the other coil can be utilized for indicating the information.

If the two channel systems are connected in such a manner that, after determining the individual lines, the channels controlling the information indication are controlled in correspondence with the signals obtained from the scanned channels, the information scanned from one line is written over into the other line, i.e., the information present on the board can be transferred to another board or to another point, and/or into another line of the respective board.

From a consideration of the foregoing disclosure, therefore, it will be evident that all of the initially recited objects of the present invention have been achieved.

Although the present invention has been described and illustrated in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily unnerstand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.