Browse Prior Art Database

Immiscible Liquid Magnetic and Nonmagnetic (Ferrofluid) Bubble Display with Magnetic Bubble Propagation and Recirculator

IP.com Disclosure Number: IPCOM000083300D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 4 page(s) / 75K

Publishing Venue

IBM

Related People

Romankiw, LT: AUTHOR [+3]

Abstract

The type of ferrofluid display involved here uses immiscible magnetic and nonmagnetic liquids, one of which liquids is pigmented with respect to the other located between two surfaces along with a bubble generating structure and bubble manipulating structures to form a visual display, by moving bubbles into desired places in a matrix, when desired.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 42% of the total text.

Page 1 of 4

Immiscible Liquid Magnetic and Nonmagnetic (Ferrofluid) Bubble Display with Magnetic Bubble Propagation and Recirculator

The type of ferrofluid display involved here uses immiscible magnetic and nonmagnetic liquids, one of which liquids is pigmented with respect to the other located between two surfaces along with a bubble generating structure and bubble manipulating structures to form a visual display, by moving bubbles into desired places in a matrix, when desired.

It has been proposed to use a magnetic field perpendicular to a ferrofluid magnetic bubble display to polarize the bubbles magnetically, analogously to use in magnetic bubble domain devices including propagation methods. This was expensive and produced magnetic field interference with adjacent unrelated equipment. However, liquid bubbles can also be propagated without a perpendicular magnetic field, using an in-plane magnetic-field rotating at only half the speed needed in the conventional bubble domain case for a given number of unit cell propagations per second.

Fig. 1 shows a ferrofluid display system in schematic form with a set of only five shift registers SR shown, to illustrate the type of display arrangement which can be provided by showing only a small fraction of the number of shift registers required for a display. The shift register may be of several varieties, such as T and I bars used with amorphous bubble domain devices or those described in connection with Figs. 2A-2E, as well as Figs. 4A-4C described below.

A reservoir V is connected to a series of bubble generators G that constantly generate bubbles at a predetermined rate which pass to bubble selector switches S, which can pass bubbles on to the register SR or back to reservoir V through line L. The bubbles are returned to reservoir V from registers SR through recirculator line R.

For controlling location of the bubbles in the field, a number of permeable shift register structures can be provided such as a double sawtooth Fig. 2A. a sawtooth 2B, a triangle Fig. 2C, a sine wave, Fig. 2D, and an angle bar, Fig. 2E.

In Fig. 3, a display using ferrofluid droplets to form images needs recycling of droplets back into a reservoir after the droplets' function ends. This recirculator is a magnetic nonmetering pump. The pump of Fig. 3 consists of a continuous sawtooth pattern 10 made of magnetic material and a rotating magnetic field. Wetting of the pattern by ferrofluid is not desired. However, there are other recirculation schemes in which it may be preferred to have the pattern or parts thereof preferentially wetted by the ferrofluid 14. In such cases, capillary forces are used to permit adequate recirculation.

Sawtooth recirculator pattern 10 surrounding the periphery of a device holding ferrofluid in a host liquid between two plates (of which one is transparent and forms the window of the display) recirculates, i.e., propagates the ferrofluid droplets 15 back to reservoir 12. Propagation patterns within...