# US 7,607,826 B2 · Thermoelastic device with preselected resistivity, inertness and deposition characteristics

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- Number: US 7,607,826 B2
- Document ID: US7607826B2
- Status: Granted
- Kind: B2
- Application number: 11/768,875
- Filed: 2007-06-26
- Published: 2007-10-18
- Granted: 2009-10-27
- Earliest claimed: 2000-10-20
- Assignees: Silverbrook Research Pty Ltd
- Inventors: Gregory John McAvoy; Kia Silverbrook
- Web page: https://patentgrep.com/patent/US7607826B2

## CPC

- B81C 99/006: {Design; Simulation}
- B41J 2/14427: {Structure of ink jet print heads with thermal bend detached actuators}
- B81B 3/0024: {Transducers for transforming thermal into mechanical energy or vice versa, e.g. thermal or bimorph actuators (electric motors using thermal effects H02N10/00)}
- B81B 3/0035: {Constitution or structural means for controlling the movement of the flexible or deformable elements}
- F03G 7/0613: {using layers of different materials joined together, e.g. bimetals}
- F03G 7/064: {characterised by its use}
- F03G 7/066: {Actuator control or monitoring}
- H01H 1/0036: {Switches making use of microelectromechanical systems [MEMS] (for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009)}
- B81B 2201/038: Microengines and actuators not provided for in B81B2201/031 - B81B2201/037
- F05C 2203/0813: Carbides
- F05C 2203/083: Nitrides
- F05C 2251/04: Thermal properties
- F05C 2251/044: similar
- F05C 2251/046: dissimilar
- H01H 2061/006: {Micromechanical thermal relay}
- H01H 2061/008: {Micromechanical actuator with a cold and a hot arm, coupled together at one end}
- B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01)
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00)
- F03G: SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR (arrangements in connection with power supply in vehicles from force of nature B60K16/00; electric propulsion with power supply in vehicles from force of nature B60L8/00)
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- F05C: INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES

## Abstract

A thermoelastic device comprising an expansive element is disclosed. The expansive element is formed from a material, which is preselected on the basis that it has one or more of the following properties: a resistivity between 0.1 μΩm and 10.0 μΩm; chemically inert in air; chemically inert in the chosen ink; and depositable by CVD, sputtering or other thin film deposition technique.

## Claims

### Claim 1

A method for selecting a material for a thermal bend actuator of a printhead nozzle comprising an expensive element formed from the material, the method including the steps of:
selecting the material from the group including silicides and carbides of titanium; borides, silicides, carbides and nitrides of tantalum, molybdenum, niobium, chromium, tungsten, vanadium, and zirconium;
selecting the material on the basis that the material has at least one of the following properties;
a resistivity between 0.1 μΩm to 10.0 μΩm;
chemically inert in air;
chemically inert in a chosen ink; and,
depositable by CVD, sputtering or other thin film deposition technique; and
selecting the material on the basis of ε, wherein εγ is a dimensionless constant for the material in accordance with the formula
ɛ
⁢
⁢
γ
=
E
⁢
⁢
γ
2
⁢
T
ρ
⁢
⁢
C
wherein E is Young's module of the material; γ is the coefficient of thermal expansion; T is the maximum operating temperature, ρ is the density and C is the specific heat capacity.

### Claim 2 (depends on 1)

The method of claim 1, wherein the dimensionless constant is normalized relative to that of silicon to a value ε , said normalized value being calculated by deriving the value εγ for the preselected material at the relevant temperature value and dividing this by the value of ε obtained for silicon at that some temperature.

### Claim 3 (depends on 1)

The method of claim 1, wherein the material is further selected on the basis of mε, where
m
ɛ
=
ⅆ
ɛ
ⅆ
T
=
E
⁢
⁢
γ
2
ρ
⁢
⁢
C
⁡
[
N
/
m
2
⁢
⁢
1
/
°
⁢
⁢
C
⁢
.
2
kg
/
m
3
⁢
⁢
Nm
/
kg
⁢
⁢
°
⁢
⁢
C
.
]