US4413170A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal printing head
Assignee: Thales SA
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Filing: 1981-06-17
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Granted: 1983-11-01
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Expires: 2001-06-17
Abstract
Abstract An electrical heating resistor of the type deposited on a substrate plate constituting the basis element of a thermal printing head. In order to concentrate the heat given off in the free surface of said heating resistor towards the paper to print, the invention provides for the deposition on the substrate of at least one layer having a relatively constant resistivity and then at least one surface layer with a non-linear resistivity and a negative temperature coefficient. Starting from a high value when cold, the resistance of the surface layer drops abruptly as soon as it reaches the triggering temperature, thus switching the heat resistor by command of a control circuit.
Inventors
- 👤 Christian Val
- 👤 Didier Pribat
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:33
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/315; B41J2/32; B41J2/335; B41J2/33505; B41J2/33515; B41J2/33535; B41J2/3355; B41J2/33555; B41J2/3357
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
103 words
A thermal printing head comprising at least one strip of linear heating resistors, wherein each resistor is deposited on an insulating glass or ceramic substrate, whose thermal capacity is well above that of the heating resistor, and wherein it comprises at least a first layer of a material having a relatively constant resistivity as a function of the temperature and which is deposited in direct contact with the substrate and at least a second surface layer of a material whose resistivity varies in non-linear manner with the temperature and having a negative temperature coefficient, said second layer being deposited on the first layer.
Claim 2
Dependent Claim
103 words
A thermal printing head comprising at least one strip of linear heating resistors, wherein each resistor is deposited on an insulating glass or ceramic substrate, whose thermal capacity is well above that of the heating resistor, and wherein it comprises at least a first layer of a material having a relatively constant resistivity as a function of the temperature and which is deposited in direct contact with the substrate and at least a second surface layer of a material whose resistivity varies in non-linear manner with the temperature and having a negative temperature coefficient, said second layer being deposited on the first layer.
Claim 3
Dependent Claim
55 words
A thermal printing head according to claim 1, wherein its resistance, which is high at ordinary temperature (20° C.) becomes low as soon as the resistivity layer traversed by a current brings the variable resistivity layer to the temperature where there is a sudden change in its resistivity, called the triggering temperature of the NTC.
Claim 4
Dependent Claim
30 words
A thermal printing head according to claim 2, wherein as soon as the variable resistivity layer reaches its triggering temperature, the heat given off is localized in said surface layer.
Claim 5
Dependent Claim
39 words
A thermal printing head according to claim 1, wherein the variable resistivity surface layer is kept at a temperature which is close to and slightly below its triggering temperature by applying a permanent current traversing the underlying resistive layer.
Claim 6
Dependent Claim
57 words
A thermal printing head according to claim 1, wherein the variable resistivity surface layer is deposited on a plurality of constant resistivity layers which in turn are deposited on said first layer, the resistivity of the constant resistivity layers decreasing from that deposited in direct contact with the substrate to that which is below the surface layer.
Claim 7
Dependent Claim
51 words
A thermal printing head according to claim 1, comprising series-connected heating resistors supplied by power transistors and controlled by control transistors, each of which authorises the passage of current through a given resistor, wherein the heating resistors are connected by direct connections to the power transistors and to the control transistors.
References Cited (Backward Citations)
US2915724A
Cited
FR2220139A5
Cited
US3973106A
Cited
FR2311410B1
Cited
US4246468A
Cited
US4206541A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-10-31 | 1987-05-02 | 1987-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-31 | 1991-05-02 | 1991-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-31 | 1995-05-02 | 1995-11-01 | $7700.00 | Window Closed / Lapsed |