US 4,779,082 AGranted

Matrix display apparatus employing movable magnetic elements

OwnerHassan P. A. Salaminventor

Life of this patent

Estimating the term…

Loading patent…

Abstract

The invention provides a display matrix system using display elements of the electromagnetic type. The system differs from others in that the currents applied to the display elements are unidirectional as there are no electrical switching components per element. This reduces the drive circuitry needed for the matrix. Selection of the display elements relies on current pulses of variable width. In accordance with an aspect of the invention each one of a row or column of coils are connected together by N conductors, such that it is only necessary to drive 1/N of the coils in a row or column at a time: In accordance with a further aspect of the invention means are provided which enable variation in the electrical pulse width applied to a display element in response to variation of one of ambient temperature and supply voltage.

Claims18

Dependent claims

In a display system comprising,

A. a matrix of display elements arranged in rows and columns, each display element comprising;
a member movable between first and second positions of contrasting appearance;
a ferromagnetic element coupled to said member;
stationary ferromagnetic flux guiding means for guiding flux towards said ferromagnetic element to cause movement of said member and,
first and second flux generating means associated with said flux guiding means;
B. a row drive circuit associated with each of the rows of display elements for providing drive current to the row, said first flux generating means of the display elements of the row being connected together for simultaneous energisation of them by the row drive circuit;
C. a column drive circuit associated with each of the columns of display elements for providing drive current to the column, said second flux generating means of the display elements of the column being connected together for simultaneous energisation of them by the column drive circuit;
D. control means for controlling the currents applied by the row and column drive circuits
wherein the improvement comprises
(a) said stationary flux guiding means comprises a part of low remanence ferromagnetic material;
(b) said display element is arranged so that the magnitude of the flux necessary to be applied by said flux guiding means to move the member from the first to to the second position is less than that of the flux necessary to be applied to move the member from the second to the first position;
(c) one of said row and column drive circuits being arranged, under control of said control means, to apply an electrical pulse of energy sufficient to cause the flux generating means connected thereto to cause movement of the respective members of the display elements from the first to the second position, and
(d) the other one of said row and column drive circuits being arranged, under control of said control means, to apply first and second electrical pulses to the flux generating means connected thereto, said first electrical pulse being of insufficient energy to move the respective members from the second to the first position and being of sufficient energy to cause the flux generating means to generate flux sufficient to substantially cancel the effect of flux generated in respect of the same display element by flux generating means connected to the said one of the row and column drive circuits so that movement of the member from the first to the second position does not occur, and said second electrical pulse being of sufficient energy to cause the flux generating means to cause movement of the respective members of the display elements from the second position to the first position.

10 more elements

In a display system comprising,

A. a matrix of display elements arranged in rows and columns, each display element comprising;
a member movable between first and second positions of contrasting appearance,
a ferromagnetic element coupled to said member,
stationary ferromagnetic flux guiding means for guiding flux towards said ferromagnetic element to cause movement of said member, and
first and second flux generating means associated with said flux guiding means;
B. a row drive circuit associated with each of the rows of display elements for providing drive current to the row, said first flux generating means of the display elements of the row being connected together for simultaneous energisation of them by the row drive circuit;
C. a column drive circuit associated with each of the columns of display elements for providing drive current to the column said second flux generating means of the display elements of the column being connected together for simultaneous energisation of them by the column drive circuit, and
D. control means for controlling the currents applied by the row and column drive circuits
wherein the improvement comprises
(a) said display element being arranged so that the magnitude of the flux necessary to be applied by said flux guiding means to move the member from the first to the second position is less than that of the flux necessary to be applied to move the member from the second to the first position.
(b) one of said row and column drive circuits being arranged under control of said control means, to apply an electrical pulse of energy sufficient to cause the flux generating means connected thereto to cause movement of the respective members of the display elements from the first to the second position, and
(c) the other one of said row and column drive circuits being arranged, under control of said control means, to apply a pulse to the flux generating means connected thereto, said electrical pulse being of insufficient energy to move the respective members from the second to the first position and being of sufficient energy to cause the flux generating means to generate flux sufficient to substantially cancel the effect of flux generated in respect of the same display element by flux generating means connected to the said one of the row and column drive circuits so that movement of the member from the first to the second position does not occur.

9 more elements

In a display system comprising;

A. a matrix of display elements arranged in rows and columns, each display element comprising;
a member movable between first and second positions of contrasting appearance,
a ferromagnetic element coupled to said member,
a flux guiding means for guiding flux towards said ferromagnetic element to cause movement of said member,
a first flux generating means associated with said flux guiding means, and
a second flux generating means associated with said flux guiding means;
B. a row drive circuit associated with each of the rows of display elements for providing electrical drive to the row, said first flux generating means of the display elements of the row being driven by said row drive circuit;
C. a column drive circuit associated with each of the columns of display elements for providing electrical drive to the column, said second flux generating means of the display elements of the column being driven by said column drive circuit, and
D. control means for controlling the currents applied by the row and column drive circuits
wherein the improvement comprises
said flux generating means of the display elements of at least one of said rows and columns are connected to the respective drive circuitry by means of N separate conductors (where N is an integer), each of the N conductors connecting together a number of the flux generating means of the at least one of the rows and columns,
and there are provided switching means connected to said conductors and under control of the control means, for selecting which of the N conductors in the at least one of the rows and columns drive current is to be applied to at any time.

9 more elements

Dependencies are inferred from the claim text.