US3898423A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Heated windows in road vehicles and control circuits therefore
Assignee: TARKA CONTROLS Ltd
•
Filing: 1973-05-15
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Granted: 1975-08-05
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Expires: 1993-05-15
Abstract
Abstract An electrically heated window in a road vehicle is provided with sensing electrodes for detecting the formation of condensation on the surface thereof. An electronic switching circuit responsive to the sensing electrodes is provided for energizing the window heater when formed condensation is sensed. A manually operable overide allows for energization of the heater through an RC or mechanical timer operable to place the electronic switching circuit in condition for energizing the heater irrespective of the presence or absence of condensation on the window.
Inventors
- 👤 John Crawshaw Taylor
- 👤 John Richard Bann
- 👤 Hamish Bayne Wedderspoon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:25
CPC Classifications
H; H05; H05B; H05B3/00; H05B3/84; B; B60; B60S; B60S1/00; B60S1/02; B60S1/56; B60S1/58; B60S1/586; H05B1/00; H05B1/02; H05B1/0227; H05B1/023; H05B1/0236; H05B2203/00; H05B2203/035
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
164 words
In a road vehicle, an arrangement for reducing condensation upon the interior surface of a window of the vehicle, the said arrangement including spaced electrodes arranged so as to be bridged resistively by condensation upon said surface; an electronic switching circuit responsive to the resistance between said electrodes; a heating element responsive to the condition of said electronic switching circuit for heating said surface; the heating element and switching circuit being arranged so that in operation the switching circuit is in a condition for energizing the heating element for so long as the resistance between said electrodes is lower than that characterizing a predetermined degree of condensation upon said surface; and a manually-operable timer adapted, when operated, to cause energization of the heating element for a predetermined period, said manuallyoperable timer including means operable to place said switching circuit in a condition for energizing said heating element irrespective of the resistance between the sensing electrodes and to maIntain such condition for said perdetermined period.
Claim 2
Dependent Claim
164 words
In a road vehicle, an arrangement for reducing condensation upon the interior surface of a window of the vehicle, the said arrangement including spaced electrodes arranged so as to be bridged resistively by condensation upon said surface; an electronic switching circuit responsive to the resistance between said electrodes; a heating element responsive to the condition of said electronic switching circuit for heating said surface; the heating element and switching circuit being arranged so that in operation the switching circuit is in a condition for energizing the heating element for so long as the resistance between said electrodes is lower than that characterizing a predetermined degree of condensation upon said surface; and a manually-operable timer adapted, when operated, to cause energization of the heating element for a predetermined period, said manuallyoperable timer including means operable to place said switching circuit in a condition for energizing said heating element irrespective of the resistance between the sensing electrodes and to maIntain such condition for said perdetermined period.
Claim 3
Dependent Claim
24 words
In a road vehicle, an arrangement as claimed in claim 1 wherein the manually-operable timer comprises an electronic timer incorporating a capacitor/resistor timing network.
Claim 4
Dependent Claim
110 words
In a road vehicle, an arrangement as claimed in claim 2 wherein the capacitor of said capacitor/resistor network is connected in series with a manually-operable normallyopen switch across the power supply terminals for the switching circuit, and the resistor of said capacitor/resistor network is connected between the capacitor and said switching circuit via an isolating diode, the arrangement being such that, after a temporary closure of said switch to charge the capacitor, the capacitor discharges via said resistor and diode to provide an input to the switching circuit such as to cause it to energize the heating element for a period determined by the rate of discharge of the capacitor.
Claim 5
Dependent Claim
120 words
In a road vehicle, an arrangement as claimed in claim 3 wherein the electronic switching circuit includes a first transistor the control electrode of which, in operation, is connected to receive current via the spaced electrodes when these are resistively bridged by condensation and a second transistor arranged to control a switching device the condition of which determines the energisation of the heating element for removing the condensation from said surface, said first transistor having in its controlled circuit a load formed by two serially connected resistors the junction between which is connected to the control electrode of the second transistor, and said resistor of the capacitor/resistor network being connected via said diode to the base of said first transistor.
Claim 6
Dependent Claim
86 words
In a road vehicle, an arrangement as claimed in claim 4 wherein the electronic switching circuit incorporated a switching device for determining the heater operation including a third bipolar transistor, of the same polarity as the first transistor and connected in common emitter configuration, and a resistor connected to provide positive feedback from the collector of the third transistor to the emitter of the first transistor to ensure that the switching circuit responds rapidly to an input condition thereby to reduce power dissipation in the transistors.
Claim 7
Dependent Claim
71 words
In a road vehicle, an arrangement as claimed in claim 5 wherein one of the electrodes is connected to one of the power supply terminals for the electronic switching circuit and the other electrode is connected via a current limiting resistor to the base and via a diode to the collector of the first transistor, the diode being poled such that it will be forward-biased should the electrodes be short circuited.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |