WO2008102213A1

WO2008102213A1 - Electromagnetic display element

Info

Publication number: WO2008102213A1
Application number: PCT/IB2007/050551
Authority: WO
Inventors: Song Lee
Original assignee: Mpot Pte Ltd
Priority date: 2007-02-21
Filing date: 2007-02-21
Publication date: 2008-08-28
Also published as: WO2008102213A8

Abstract

An electromagnetic display element (1) capable of displaying gray scale or color shades is disclosed. The electromagnetic display element has the advantage of not needing electrical power to maintain its color states. Collectively, they are able to display richer images then existing electromagnetic display elements. The electromagnetic display element comprises of a body (3) with an internal hole of a color, a magnetic nucleus of another color within it, a front light filter (2), and electromagnets to control and move the nucleus forward or backward to display gray scale or color shades accordingly.

Description

ELECTROMAGNETIC DISPLAY ELEMENT

Technical Field

[1] The present invention relates to a display element of a display device, more particularly, although of course not solely limited to, an electromagnetic display element.

Background Art

[2] Dynamic display devices, which are capable of displaying moving or changing images, are normally formed by an array of display elements which collectively produce an image. Examples of dynamic display devices include liquid crystal display (LCD) panels, plasma display panels, light emitting diode (LED) display panels and electromagnetic display panels, which are made up of array of liquid crystal display elements, plasma display elements, light emitting diode display elements and electromagnetic display elements respectively. Electromagnetic display elements have the advantage of not requiring electrical power to maintain its color state compared to other dynamic display elements.

[3] An electromagnetic display element typically represents a 'dot' in an image. Current electromagnetic display element tends to display only either of two colors.

[4] One such example is US Patent No. 5,898,418. It discloses an electromagnetic display element capable of displaying either of two colors. It comprises of a frame of a color, and a plate with one side of similar color to the frame and another side of different color from the frame pivotally mounted onto the frame. The display element displays the color of the plate and the color can be changed by flipping the plate. The flipping of the plate, which has a magnet embedded in it, is controlled by a U-shaped ferromagnetic element with a solenoid mounted onto it. Current applied to the solenoid will cause the U-shaped element to be magnetized. By controlling the current direction, the magnetic polarity of the U-shaped ferromagnetic element can be controlled or changed and the plate can be made to flip accordingly by magnetic repulsion and attraction between them to reveal the required color. Another similar example is US Patent No. 6,272,778. It improves upon the earlier invention by using a straight electromagnetic core instead of a U-shaped element.

[5] US Patent No. 6,326,945 discloses another electromagnetic display element that displays either of two colors in a different way. The electromagnetic display element comprises of a cell, which has a display front, filled with an opaque masking liquid of one color and a magnetic assembly of another color. When the magnetic assembly is at the front end of the cell, the display element displays the color of the magnetic assembly. When the magnetic assembly is at the back end of the cell, the display element displays the color of the masking fluid. An electromagnet placed at the bottom of the cell is used to control the movement of the magnetic assembly, which is free floating in a linear direction away or toward the display front and comprises of a magnet placed inside the forward end of an aluminum tube. By changing the direction of the current flow in the electromagnet, the magnetic assembly will either be attracted towards the electromagnet and move away from the display front or repelled away from the electromagnet and move towards the display front. In such a way, either the color of the magnetic assembly or the masking fluid can be displayed. Disclosure of Invention

Technical Problem

[6] Current electromagnetic display element tends to display only either of two colors.

It is unable to display gray scale or color shades. As a result, the collective display effect of electromagnetic display elements tends to be not as rich as other display devices. Its use is often limited to displaying words or numbers, instead of images and pictures, even though it has the advantage of not requiring electrical power to maintain its color state.

[7] The object of this invention is to have an electromagnetic display element capable of displaying gray scale or color shades, while still keeping the advantage of not requiring electrical power to maintain its color state.

Technical Solution

[8] The first step is to have a display element capable of displaying gray scale or color shades.

[9] Consider a display element comprising of a long black cell tube and a white cell nucleus within the cell tube. Looking from the front end of the cell tube, the display element will appear white when the white cell nucleus is at the front end. This is because light will be reflected back by the white cell nucleus. Again looking from the front end of the cell tube, the display element will appear black when the white cell nucleus is at the back end. This is because ambient light is multidirectional and most of it will be absorbed by the black cell tube when it enters the front end of the black cell tube and very little light will reach the cell nucleus and even less light will be reflected back to the front end. When the white cell nucleus is at various depths within the cell tube, various amounts of light will be reflected back from the cell nucleus. As such, various shades of black or white, or gray scale of black or white can be displayed.

[10] Experiment has shown that the length of the cell tube needs to be more than eight times the length of the opening for the cell nucleus to be hardly noticeable when it is at the back of the cell tube. The length of the cell tube can be reduced by introducing a light filter at the front of the cell tube to either reduce the amount of light entering the cell tube or diffusing the light or both. The length of the cell tube can be reduced to less than two times the size of the opening with the light filter.

[11] The color of the display element will depend on the color of the cell nucleus and the cell tube. For a red display element, the cell nucleus can be red while the cell tube can remain black. Similarly, for a blue display element, the cell nucleus can be blue, and so on. An alternative would be to vary the color of the cell tube and cell nucleus to achieve even greater color shades. For example, a display element with a red cell tube and green cell nucleus will display green when the cell nucleus is at the front end of the cell tube and will display red when the cell nucleus is at the back end of the cell tube. When the cell nucleus is somewhere in between the front and back of the cell tube, the display element will display some red and some green and the amount of red and green depend on the position depth of the cell nucleus within the cell tube. Another alternative is to have colored filter to provide the color of the display element. For example, while keeping the cell tube black and cell nucleus white, then a red display element can be made with a red filter, while a blue display element can be made with a blue filter, and so on.

[12] The second step is to have a control device that can make the cell nucleus move forward towards the cell opening or backwards towards the back of the cell to achieve various gray scale or color shades as described earlier.

[13] Consider the display element above further comprising of a control device of electromagnets, and the cell nucleus further comprising magnetic material. Magnetic field can be created by current flowing in the electromagnets so as to make the cell nucleus move forward or backward within the cell tube through magnetic attraction or repulsion between the electromagnets and cell nucleus. While the term electromagnet is used here, it could mean a single loop formed by electrical conductor, or many loops formed by electrical conductor or electrical conductor coiled round a soft magnetic material or even electrical conductor in other shapes or forms whereby electrical current flowing in the electrical conductor will generate magnetic field.

[14] The control mechanism can be designed to create fixed (or stepped) states or continuous states of gray scale or color shades. The simplest would be a two-state gray scale or color shade such as black and white.

[15] The technical solution will become clearer when the description and embodiments are read.

Advantageous Effects

[16] The present invention allows the use of the electromagnetic display element to display gray scale or color shades. Collectively, the electromagnetic display elements will be able to display richer images. It also has the usual advantage of other electromagnetic display elements such as the ability to maintain its color state without the need for continuous electrical power source. Description of Drawings

[17] The accompanying drawings are solely for purposes of illustrating the concepts of the invention and are not drawn to scale. The embodiments shown in the accompany drawings, and described in the accompanying detailed description, are used as illustrative embodiments and should not be construed as the only manner of practicing the invention. Also, the same reference numerals, possibly supplemented with reference characters where appropriate, have been used to identify similar parts. These and other objects and features of this invention will be clear and apparent to those skilled in the art upon reading the detailed description together with the drawings, wherein:

[18] FIG. 1 is a perspective view of an electromagnetic display element;

[19] FIG. 2 is the side view of the electromagnetic display element;

[20] FIG. 3 is the longitudinal cross-section 5-5 in FIG. 2 of the electromagnetic display element;

[21] FIG. 4a,4b, 4c and 4d are the transverse cross-sections 6-6 in FIG. 2 of the various possible positions of nucleus inside the electromagnetic display element;

[22] FIG. 5a,5b, 5c and 5d are the transverse cross-sections of an electromagnetic display element with only two electromagnets and wherein the key is made of permanent magnetic material;

[23] FIG. 6 is a perspective view of an alternative embodiment of an electromagnetic display element;

[24] FIG. 7 is the side view of the alternative embodiment of the electromagnetic display element;

[25] FIG. 8 is the longitudinal cross-section 25-25 in FIG. 7 of the alternative embodiment of the electromagnetic display element; and

[26] FIG. 9 is the longitudinal cross-section of the alternative embodiment of the electromagnetic display element with only one electromagnet and wherein the key is made of permanent magnetic material.

Best Mode

[27] Referring to FIG. 1 and FIG. 2, the present invention of an electromagnetic display element 1, or the apparatus 1, comprises of a body 3, a light filter 2 secured to the body by glue or other means, and electromagnets 8a, 8b, 8c and 8d (8d is hidden), in which each electromagnet 8 is represented by a loop.

[28] The body 3 is black in color so as to absorb light and can be made of plastic. The light filter 2 can be made of tinted plastic or by clear plastic with a light reducing film added to one surface which reduces the amount of light through.

[29] Referring to FIG. 3, which is the longitudinal cross-section 5-5 in FIG. 2, the apparatus 1 further comprises of a nucleus 10, which is shaped as a round rod with its sides threaded like a screw. The body 3 has an internal threaded hole 7. The pitch and angle of the threads of the internal hole 7 of the body 3 and the nucleus 10 are the same. The nucleus 10 fits into the internal threaded hole 7 of the body 3. By turning the nucleus 10 in an anti-clockwise direction within the body 3, the nucleus 10 will move forward towards the light filter 2. Each full revolution will move the nucleus 10 forward by the size of the pitch of the thread. Conversely the nucleus 10 will move backward away from the light filter if it is turned in a clockwise direction. The nucleus 10 has a rectangular key 11 made of soft magnetic material inserted into it.

[30] The electromagnet 8 is used here to describe any device capable of generating the required magnetic field to achieve its objective, which is to influence the nucleus to move forward or backward. While it is shown here as a single loop of copper electrical conductor, it could also be many loops if larger magnetic field is required. It could also be electrical conductors coiled round a soft magnetic core if even larger magnetic field is required. The strength of the magnetic field required depends on the size of the apparatus 1. The bigger the apparatus 1, the larger the magnetic field will be required.

[31] The light filter 2 is used here to reduce the length of the apparatus 1, although the light filter 2 is not a must for the apparatus 1 to function or to provide gray scale or color shades.

[32] The internal threaded hole 7 of the body 3 is also black in color. The nucleus 10 is white in color and made of plastic. The contrasting color between the body 3 and the nucleus 10 makes the display clearer. The key 11 is made of iron. It should be appreciated that the colors, shapes, properties, materials and arrangements described here are not the only solution. It should be clear for others skilled in the art to be able to use alternative colors, shapes, properties, materials and arrangements for the apparatus 1.

[33] Referring to FIG. 4a, 4b, 4c and 4d, which are the transverse cross-sections 6-6 in

FIG. 2, the figures show the various positions of the nucleus 10 within the body 3. The nucleus 10 can be made to rotate either clockwise or anti-clockwise by turning on and off the electromagnets 8a, 8b, 8c and 8d one -by-one in a clockwise or anti-clockwise direction respectively. This is because the soft magnetic material of the key 11 would want to be aligned to the axis of the magnetic field generated by the electromagnet that is turned on. In this arrangement, the axis of the magnetic field generated by the electromagnet 8 is perpendicular to the direction of the internal hole 7 and the rotation of the nucleus 10 as a result of the key aligning itself with the magnetic field makes the nucleus rotate and move. For example, starting with FIG. 4a, the electromagnet 8a is turned on. The magnetic field will attract the soft magnetic key 11 up toward the electromagnet 8a. Thereafter, the electromagnet 8a is turned off. At this stage, the nucleus 10 will remain in position due to contact forces between the nucleus 10 and the threads of the internal hole 7. Next, electromagnet 8b is turned on. The key 11 will rotate from its vertical position in FIG. 4a to the horizontal position in FIG. 4b in an anticlockwise direction because it is attracted to the electromagnet 8b. This means that the nucleus 10 will move forward towards the light filter 2 by a distance of a quarter of the pitch of the thread. After that, the electromagnet 8b is turned off. Again, the nucleus 10 will stay in position. Next, the electromagnet 8c is turned on and then off, before the electromagnet 8d is turned on and then off. Referring to FIG. 4b, 4c and 4d, the nucleus will continue to rotate in an anti-clockwise direction due to the attraction of the electromagnets 8 have on the soft magnetic key 11 when the electromagnets 8 are turned on and off one-by-one in sequence. This sequence can be continued if it is required for the nucleus to continue to move forward, or reversed if it is required for the nucleus to move backward.

[34] When the nucleus 10 is at the front of the internal hole 7 near the light filter 2, the apparatus 1 displays the color of the front of the nucleus 10 facing the light filter 2, or white in this case. When the nucleus 10 is at the back of the internal hole 7 far away from the light filter 2, the apparatus 1 displays the color of the internal hole 7 of the body 3, or black in this case. Different shades or gray scale can be displayed according to the depth position of the nucleus 10 within the internal hole 7 of the body 3. Hence by controlling the electromagnets 8, the nucleus 10 can be made to move either forward or backward by a controlled distance in steps of one-quarter of the pitch of the tread. According to FIG. 3, it takes four revolutions for the nucleus 10 to move from the front of the internal hole 7 to the back of the internal hole 7. In other words, the cell nucleus 10 can be four times four or sixteen numbers of depth positions, or sixteen gray scales or color shades. Color shades of other colors can be achieved by changing the color of the nucleus 10, or adding a color filter property to the light filter 2.

[35] On the same concept of using the threaded nucleus 10 and threaded internal hole 7 of the body 3, a permanent magnet can be used for the key 11 instead of soft magnetic material. In such a case, the apparatus 1 will only need two electromagnets 8a and 8b rather than four electromagnets as the polarities of the electromagnets and the permanent magnet can be used to achieve the same object of making the nucleus 10 rotate in either an anti-clockwise or clockwise direction to move forward or backward.

[36] Referring to FIG. 5a, 5b, 5c and 5d, which are the transverse cross-sections 6-6 in

FIG. 2 of the apparatus 1 with only two electromagnets 8a and 8b and whereby the key 11 is made of permanent magnet. The key 11 is longer with the polarities as shown whereby the positive sign refers to the north-pole and the negative sign refers to the south-pole of the permanent magnet.

[37] To achieve a similar effect of making the nucleus 10 rotate in an anti-clockwise direction and moving forward, the electromagnet 8a is turned on with the negative pole facing the body 3 to attract the positive pole of the key 11. Thereafter it is turned off. Next, the electromagnet 8b is turned on with the negative pole facing the body 3 to attract the positive pole of the key 11. Thereafter it is turned off. Next, the electromagnet 8a is turned on again but with the positive pole facing the body 3 to attract the negative pole of the key 11. Thereafter it is turned off. Next the electromagnet 8b is turned on again but with the positive pole facing the body 3 to attract the negative pole of the key. In such a sequence on turning on and off of and changing of polarities of the electromagnets 8a and 8b, the key 11 is made to rotate in an anti-clockwise direction as in FIG. 5a to FIG. 5b to FIG. 5c and to FIG. 5d. Through the anticlockwise rotation of the nucleus 10, the nucleus 10 will move forward towards the light filter 2. Similarly, the nucleus 10 can be made to rotate in a clockwise direction and the nucleus 10 will move backward away from the light filter 2.

[38] Above are examples where there are sixteen fixed gray scales or color shades. The apparatus can be designed and built to have more or less number of fixed gray scales or color shades by changing the number of revolutions the nucleus 10 can turn, number of electromagnets 8 (such as six electromagnets around a hexagonal or round body), the length of internal hole 7, or others.

Alternative Mode of Invention

[39] An alternative mode of invention is to do away with the threads in the internal hole and the nucleus. The nucleus can still move forward or backward within the internal hole of the body. Electromagnets are arranged such that its axis of magnetic field is aligned with the direction of the required movement of the nucleus.

[40] Referring to FIG. 6 and 7, which is the perspective view and side view of the alternative embodiment of an electromagnetic display element 21, it is similar to FIG. 1 and 2 in that it also has a body 23, a light filter 22 and electromagnets 28a and 28b. However the arrangement of the electromagnets 28a and 28b are different from 8a and 8b in FIG. 1.

[41] Again here, the electromagnet 28 is depicted by a single electrical conductor loop, although it can represent also multiple loops, or the loops coiled around a soft magnetic hollow core, and can be placed further front or back.

[42] Referring to FIG. 8, which is the longitudinal cross-section 25-25 of the electromagnetic display element 21, the key 31 is made of soft magnetic material. To make the nucleus 30 move backward, the electromagnet 28a is turned on. The key 31 will be attracted to the electromagnet 28a and move backward. When the electromagnet 28a is turned off, the nucleus 30 will remain in position because of contact forces, namely friction and reaction, between the nucleus 30 and the internal hole 27 of the body 23. To make the nucleus 30 move forward, the electromagnet 28b is turned on. The key 31 will be attracted to the electromagnet 28b and move forward towards the light filter 22. The amount that the nucleus 30 will move forward or backward depends on the strength and duration of the electromagnet 28 is turned on. It is possible to make the nucleus 30 move by a small distance by turning on the electromagnet 28a or 28b for a very short duration, although it is difficult to control the exact amount the nucleus 30 will move.

[43] If the key 31 is made of permanent magnetic material, then the number of electromagnets can be reduced to one. Referring to FIG. 9, only one electromagnet 28a is present. The key 31 is made of permanent magnetic material with the south and north- poles represented by the negative and positive signs respectively in the figure. The electromagnet 28a can generate a north-pole facing the key 31 and attract the key 31 and nucleus 30 backward or a south-pole facing the key 31 and repel the key 31 and nucleus 30 forward by changing the direction of the current in the electromagnet 28a.

[44] Comparing the best mode and the alternative mode, for the best mode, the movement forward or backward is well controlled and in fixed amounts, whereas for the alternative mode, the movement forward or backward can be by any amount, although difficult to control. In other words, the best mode offers fixed gray scales or color shades while the alternative mode offers continuous gray scales or color shades.

[45] While it is disclosed here the use of electromagnets as control device to influence and move the nucleus forward or backward, it is possible to use other control devices. Someone skilled in the art will be able to use other control devices following the concept of this invention to achieve the same objects.

Industrial Applicability

[46] The electromagnetic display element can be used together to form dynamic display panel, dynamic advertising banner, or dynamic signage. It should be appreciated that this invention can be used in many other areas as well.

[47] While the present invention has been explained by reference to the preferred embodiments described above, it will be appreciated that the embodiments are only illustrated as examples to assist understanding of the present invention and are not meant to be restrictive on its scope. In particular, the scope, ambit and spirit of this invention are meant to include the general principles of the invention as inferred or exemplified by the embodiments described above. More particularly, variations or modifications which are obvious or trivial to persons skilled in the art, as well as improvements made on the basis of the present invention, should be considered as falling within the scope and boundary of the present invention.

[48] Furthermore, while the present invention has been explained by reference to a electromagnetic display element, it should be appreciated that the invention can apply, whether with or without modifications, to other display elements without loss of generality.

Claims

Claims [ 1 ] What is claimed is :

1. A display element comprising of: a body with an internal hole of a color; a nucleus of another color within said internal hole of said body; and a control device to make said nucleus move forward or backward within said internal hole of said body to make said display element display gray scale or color shades.

[2] 2. The display element of claim 1, further comprising of a light filter secured to the front of said body.

[3] 3. The display element of claim 2, wherein said light filter disperses light.

[4] 4. The display element of claim 2, wherein said light filter reduces the amount of light entering said hole of said body.

[5] 5. The display element of claim 1, wherein said internal hole is threaded and said nucleus is threaded with same pitch and angle.

[6] 6. An electromagnetic display element of claim 1, wherein said nucleus further comprising of a key made of magnetic material.

[7] 7. The electromagnetic display element of claim 6, wherein said control device comprises of one or more electromagnets.

[8] 8. The electromagnetic display element of claim 7, wherein said electromagnet comprises of an electrical conductor loop.

[9] 9. The electromagnetic display element of claim 7, wherein said electromagnet comprises of electrical conductor loops.

[10] 10. The electromagnetic display element of claim 7, wherein said electromagnet comprises of electrical conductor loops coiled round a hollow soft magnetic core.

[11] 11. The electromagnetic display element of claim 7, wherein said electromagnet is arranged so that the axis of the magnetic field generated is in the same direction as the direction of said internal hole of said body.

[12] 12. The electromagnetic display element of claim 7, wherein said electromagnet is arranged so that the axis of the magnetic field generated is perpendicular to the direction of said internal hole of said body.

[13] 13. An electromagnetic display element comprising of: a body with a threaded internal hole of a color; a light filter secured to the front of said body; a nucleus of another color, which is threaded with same pitch and angle as said threaded internal hole, said nucleus further comprising of magnetic material; and a plurality of electromagnets able to make said threaded nucleus rotate by predetermined amounts and move either forward or backward in said hole by a fixed distance to create a fixed number of gray scale or color shades. [14] 14. An electromagnetic display element comprising of: a body with an internal hole of a color; a light filter secured to the front of said body; a nucleus of another color within said body, said nucleus further comprising of magnetic material; and one or more electromagnets able to influence said nucleus to move either forward or backward in said hole to create a gray scale or color shades.