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Direct Viewing Real Size Magnetic Bubble Display

IP.com Disclosure Number: IPCOM000084152D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 5 page(s) / 78K

Publishing Venue

IBM

Related People

Chang, IF: AUTHOR

Abstract

Magnetic bubble domain devices have been suggested for display applications. However, these devices often require complex optics, such as polarizers, analyzers, compensators, and the like. In addition, these devices show limited contrast ratio. Moreover, for small bubble domains and single crystal magnetic materials, only projection display is possible, and direct viewing is not practical. Nevertheless, the possibility of combining display, memory and logic capabilities in one medium is always appealing in terms of cost/performance.

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Direct Viewing Real Size Magnetic Bubble Display

Magnetic bubble domain devices have been suggested for display applications. However, these devices often require complex optics, such as polarizers, analyzers, compensators, and the like. In addition, these devices show limited contrast ratio. Moreover, for small bubble domains and single crystal magnetic materials, only projection display is possible, and direct viewing is not practical. Nevertheless, the possibility of combining display, memory and logic capabilities in one medium is always appealing in terms of cost/performance.

Recently, with the demonstration of bubble domain operation in amorphous magnetic material on a relatively large substrate, the goal of achieving a direct- view display system with bubble domain technology becomes feasible.

As will be described with reference to the figures, two magnetic bubbles are utilized here, one being the magnetic bubble domain in magnetic material which provides memory and logic functions, and the other being a magnetic film coated glass bubble which serves as the display medium. The bubbles are magnetically coupled to form a simple direct-view display system.

Through bubble-bubble (magnetic domain and magnetic glass bubble) interaction or coupling, the magnetic bubble domains are, in effect, amplified in size for simple viewing without the use of complicated optics. In an alternative arrangement, the magnetic glass bubbles alone are driven by T-I bar or conducting stripe arrangements to perform storage display operation, in an analog of conventional magnetic bubble domain operation.

The magnetic interaction or coupling between the magnetic domain bubbles and the magnetic glass bubbles is illustrated schematically in Fig. 1. Bubble 1 is a magnetic bubble domain in a magnetic material layer 3. Bubble 2 is a glass bubble, such as available from the 3M Company, bubble diameter ranging from 25 mu - 150 mu and wall thickness of 1 mu, or other light-weighted sphere, coated with a thin magnetic film (for example, permalloy) of appropriate thickness and uniformity, such

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Specific numerical calculations have been made which demonstrate that the interaction forces are quite adequate for addressing, i.e., for moving glass bubble 2 via magnetic bubble 1 in magnetic bubble domain material 3. For example, let M = 1200 gauss, M(2) = 10K gauss, a = 5 mu, d = 8mu, b = 90 mu, t = 1000 Angstroms, rho = 50 mu, Z = 50 mu, F(bd).u(rho) = 3.9 X 10/-9/ Newton > 10/+9/ Newton of bubble weight.

Fig. 2A shows one manner in which the magnetic film coated bubbles 2 may be used as display medium, such as, for example, light scattering elements. Typically, these bubbles are placed on magnetic layer 3 such that magnetic bubble domains can be generated and coupled to them. Two positions are defined for each glass bubble, i.e., a light scattering position (1 state) and nonscattering position (0 state). Bubble generator 5 generates the magnetic

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