# US 8,770,981 B2 · Actuation mechanism for braille displays

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- Number: US 8,770,981 B2
- Document ID: US8770981B2
- Status: Granted
- Kind: B2
- Application number: 12/771,336
- Filed: 2010-04-30
- Published: 2011-11-03
- Granted: 2014-07-08
- Earliest claimed: 2010-04-30
- Assignees: Board of Trustees of Northern Illinois University
- Applicants: David Schroeder; Graham Bogda; Brendan Vishoot
- Inventors: David Schroeder; Graham Bogda; Brendan Vishoot
- Web page: https://patentgrep.com/patent/US8770981B2

## CPC

- G09B 21/004: {Details of particular tactile cells, e.g. electro-mechanical or mechanical layout}
- G09B: EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS (devices for psychotechnics or for testing reaction times A61B5/16; games, sports, amusements A63; projectors, projector screens G03B)

## Abstract

According to the present invention, there is provided an improved refreshable tactile display apparatus including a housing, bias compression springs, sliding blocks, pins, and a shape memory alloy wire. The sliding block is actuated by the interaction between the bias compression spring and the shape memory alloy wire. The shape memory alloy wire is then activated by current driven from a power supply in either a modulated or unmodulated fashion.

## Claims

### Claim 1

A refreshable tactile display pin comprising:
a pin that can be raised and lowered, and
a sliding block slidable to contact said pin and raise said pin, and to retract from contact with said pin and render lowerable said pin, said sliding block connected to a single bias compression spring for biasing said sliding block into contact with said pin, said sliding block being additionally connected to a single wire having shape memory properties that upon activation shortens in length in opposition to said bias compression spring, for causing said sliding block to retract from contact with said pin;
wherein the single compression spring and single wire extend from only a first side of the sliding block.

### Claim 2 (depends on 1)

The display pin of claim 1, wherein said wire is defined as a nitinol wire.

### Claim 3 (depends on 1)

The display pin of claim 1, wherein said wire is activated with an electric current.

### Claim 4 (depends on 1)

The display pin of claim 1, further including a power supply for providing an electric current to the wire.

### Claim 5 (depends on 1)

The display pin of claim 1, further including a pulse modulator for modulating the electric current applied to the wire.

### Claim 6 (depends on 1)

A refreshable tactile display apparatus comprising: a plurality of tactile display pins as described in claim 1, and a housing for containing the plurality of pins.

### Claim 7 (depends on 6)

The display apparatus of claim 6, wherein said wire is defined as a nitinol wire.

### Claim 8 (depends on 6)

The display apparatus of claim 6, wherein said wire is activated with an electric current.

### Claim 9 (depends on 6)

The display apparatus of claim 6, further including a power supply for providing an electric current to the wire.

### Claim 10 (depends on 6)

The display apparatus of claim 6, further including a pulse modulator for modulating the electric current applied to the wire.

### Claim 11 (depends on 6)

The display apparatus of claim 6, wherein said housing is constructed from an acetal copolymer.

### Claim 12 (depends on 6)

The display apparatus of claim 6, wherein said housing includes cooling holes for heat dissipation.

### Claim 13

A refreshable tactile display pin comprising:
a pin that can be raised and lowered, and
a sliding block slidable to contact said pin and raise said pin, and to retract from contact with said pin and render lowerable said pin, wherein the sliding block comprises:
a first end;
a bias compression spring connected to only the first end of the sliding block for biasing the sliding block into contact with the pin;
a wire having shape memory properties connected to only the first end of the sliding block; and
a second end opposite the first end;
wherein the wire moves the second end of the sliding block into and out of contact with the pin.

### Claim 14 (depends on 13)

The display pin of claim 13, wherein said wire is defined as a nitinol wire.

### Claim 15 (depends on 13)

The display pin of claim 13, wherein said wire is activated with an electric current.

### Claim 16 (depends on 15)

The display pin of claim 15, further including a pulse modulator for modulating the electric current applied to the wire.

### Claim 17 (depends on 13)

A refreshable tactile display apparatus comprising: a plurality of tactile display pins as described in claim 13, and a housing for containing the plurality of pins.

### Claim 18 (depends on 17)

The display apparatus of claim 17, wherein said wire is defined as a nitinol wire.

### Claim 19 (depends on 17)

The display apparatus of claim 17, wherein said housing is constructed from an acetal copolymer.

### Claim 20 (depends on 17)

The display apparatus of claim 17, wherein said housing includes cooling holes for heat dissipation.