EP0408853A2 - Electrical heating device for the reflective surface of a vehicle rearview mirror - Google Patents

Electrical heating device for the reflective surface of a vehicle rearview mirror Download PDF

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Publication number
EP0408853A2
EP0408853A2 EP90109114A EP90109114A EP0408853A2 EP 0408853 A2 EP0408853 A2 EP 0408853A2 EP 90109114 A EP90109114 A EP 90109114A EP 90109114 A EP90109114 A EP 90109114A EP 0408853 A2 EP0408853 A2 EP 0408853A2
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EP
European Patent Office
Prior art keywords
resistor
temperature
semiconductor switch
heating
stage
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Application number
EP90109114A
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German (de)
French (fr)
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EP0408853A3 (en
Inventor
Rudolf Kaspar
Peter Fürst
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Hohe KG
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Hohe KG
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Publication of EP0408853A2 publication Critical patent/EP0408853A2/en
Publication of EP0408853A3 publication Critical patent/EP0408853A3/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/84—Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields
    • H05B3/845—Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields specially adapted for reflecting surfaces, e.g. bathroom - or rearview mirrors

Definitions

  • the invention relates to an electrical heating device for a mirror glass of a motor vehicle mirror with a heating conductor applied to a carrier and a temperature control device which has a temperature-dependent resistor arranged near the carrier.
  • a thermostat is connected in series with the heating conductor.
  • the installation of a thermostat near the support or on the mirror glass to be heated requires a lot of space, which is neither in an interior mirror nor in an exterior mirror of modern design.
  • a thermostat has the disadvantage that it sometimes switches with a deviation of a few degrees K from the set temperature switching points. This disadvantage is particularly important when the distance between the temperatures at which the thermostat is to switch should only be a few degrees K.
  • the invention is therefore based on the object of providing an electrical heating device for a mirror glass of a motor vehicle mirror, the temperature control device of which takes up little space and more precisely switches on or off at the set temperatures.
  • an actuating signal is formed with the resistor, the resistance value of which changes continuously with temperature, which controls a semiconductor switch influencing the current flow through the heating conductor.
  • a feedback, two-stage amplifier circuit is recommended, the control input of which is supplied with the control signal and the second stage of which is the semiconductor switch, advantageously a V-Mos field effect transistor.
  • the control signal can be formed in a simple manner in that the first stage of the amplifier circuit is connected in parallel from the resistor and a further, temperature-independent resistor, the connection point between the resistor and another resistor being connected to the control input of the amplifier circuit.
  • the high-impedance feedback connected to the control input is expediently tapped at the connection point between the heating conductor and the semiconductor switch.
  • a particularly sensitive setting of the switching temperatures is achieved if, in a further development of the invention, the ratio of the resistance values of the resistor to the further resistor and to the third resistor provided in the feedback behaves approximately as 10: 1: 100.
  • the temperature control device is constructed on a small circuit board, it is sufficient to regulate the temperature of the mirror glass if the resistance is kept on the circuit board both at a distance from both the carrier and the mirror glass. If the resistor is held on the side of the board facing away from the carrier and the mirror glass, the thermal coupling can expediently be produced through an opening provided in the board below the resistor.
  • the mirror glass support plate 26 shown in FIGS. 1 and 2 can be fastened to a mirror holder of a motor vehicle exterior mirror by means of a fastening ring in the manner described in German patent specification 29 07 433.
  • the mirror glass carrier plate 26 has a central opening 19 through which a double-sided adhesive tape 18 is visible, with the aid of which the mirror glass 20 is glued onto the front side of the mirror glass carrier plate 26 which cannot be seen in FIG. 1.
  • the mirror glass carrier plate 26 has two opposite flat surface pieces 16, 17, of which the surface piece 16 is closer to the vehicle than the region 17 when the mirror glass carrier plate 26 is installed in a motor vehicle exterior mirror.
  • a hood-like formation 29 is formed from the plastic glass carrier plate 26, which has an electronic temperature control device designated as a whole by 24 houses. From the slots in the hood 29 there are connecting lugs 21, 22 projecting outwards, onto which connecting plugs which can be connected to the poles of the vehicle battery can be attached.
  • the electronic temperature control device 24 is part of a heating device for the mirror glass 20, designated as a whole by 15, which is shown in FIG. 3.
  • the heating device 15 has an electrically insulating plate-shaped carrier 27, on which a heating element 2 in the form of conductor track coils, as shown in FIG. 3, is applied.
  • a circuit board 23 is fastened, on which the temperature control device 24 is constructed.
  • the carrier 27 is glued between the mirror glass 20 and the front of the mirror glass carrier plate 26 so that the board 23 is housed in the hood 29.
  • the carrier 27, which consists for example of a 0.3 mm thick film, is not shown separately in FIG. 2.
  • the heating element 2 is designed so that it can provide a heating power of 20 watts with an applied DC voltage of 12 volts.
  • connection contact 21 is connected to the positive voltage pole of the vehicle battery of 12 volts and the connection contact 22 is connected to the negative pole of the battery.
  • connection contacts 21, 22 there is a series connection of the heating element 2, which has practically only ohmic resistance, and the drain-source path of a V-Mos field-effect transistor 4.
  • voltage-carrying connection contact 21 there is a series connection of a first Resistance of, for example, 1 kilohm and a Zener diode 5 are connected at the junction point 14 for the purpose of voltage stabilization, the free end of the Zener diode being at the potential of the pin 22.
  • a collector resistor 8 Between the node 14 and the potential of the pin 22 is a series connection of a collector resistor 8 and the collector-emitter path of an npn transistor 3.
  • the emitter of the transistor 3 is on the Potential of the pin 22.
  • the gate of the field effect transistor 4 is connected to the collector terminal of the transistor 3.
  • a further series circuit comprising a temperature-dependent resistor 1 and an essentially temperature-independent resistor 7, the free end of which is at the potential of the connecting pin 22.
  • the connection point 6 of the resistors 1 and 7 is on the one hand at the gate of the transistor 3 and on the other hand via the feedback resistor 9 at the connection point between the heating element 2 and the field effect transistor 4.
  • the resistor 1 has a negative temperature coefficient.
  • the ratio of the ohmic resistance values of the resistor 1, the further resistor 7 and the feedback resistor 9 is approximately 10: 1: 100.
  • the feedback amplifier circuit formed from a first stage with transistor 3 and a second stage with field effect transistor is operated in large signal mode, so that transistor 3 essentially exhibits a Schmitt trigger behavior and the field effect transistor operates as a power switch.
  • the potential at node 6 is determined analogously by the resistance value of resistor 1, which changes with the temperature detected by resistor 1. There is thus an analog control signal at circuit point 6, which is fed to the input of the amplifier circuit. In this way, based on the temperature detected by the PTC resistor 1, a very precise switching on or off of the current through the field effect transistor 4 and thus through the heating element 2 is achieved.
  • the circuit also works in the manner described with a thermistor, the resistance value of which therefore has a positive temperature response.
  • the heating conductor must then be switched instead of the additional resistor 7 and the additional resistor instead of the PTC thermistor 1.
  • the resistor 1 is located on the side of the carrier 27 and the mirror glass 20 facing away from the Circuit board 23.
  • a through opening is introduced into the circuit board 23 under the resistor 1. The temperature detected by the resistor therefore follows the temperature of the carrier 27 and the mirror glass 20 with a delay.
  • the temperature control device 24 can be accommodated on the surface section 16 between the mirror glass 20 and the glass support plate 26 instead of the surface section 16, as shown in FIG. 1, so that the temperature control device 24 after installation of the mirror glass support plate 26 in an outside mirror on the vehicle distal end of the mirror glass 20 is housed and thus the outer, removed from the vehicle, usually colder areas of the mirror glass in terms of temperature.
  • the switch-on point of the mirror heater can be set to 27 ° Celsius by appropriate dimensioning of the resistance network and the switch-off temperature of the mirror heater to 30 ° Celsius.

Abstract

An electrical heating device is described for the reflective surface of a motor vehicle rear view mirror, having a heating conductor, which can be fitted to a support, and a temperature regulating device, which has a temperature-dependent resistor arranged close to the support. In order to achieve a situation where the temperature regulating device requires little installed space and switches on or off more precisely at the set temperatures it is provided that the resistor is used to form an actuating signal which controls a semiconductor switch that influences the current flow through the heating conductor. <IMAGE>

Description

Die Erfindung betrifft eine elektrische Heizeinrichtung für ein Spiegelglas eines Kraftfahrzeugspiegels mit einem auf einen Träger aufgebrachten Heizleiter und einer Temperaturregeleinrichtung, welche einen nahe dem Trager angeordneten temperaturabhängigen Widerstand aufweist.The invention relates to an electrical heating device for a mirror glass of a motor vehicle mirror with a heating conductor applied to a carrier and a temperature control device which has a temperature-dependent resistor arranged near the carrier.

Bei dieser aus der deutschen Offenlegungsschrift 26 45 231 bekannten Einrichtung ist ein Thermostat mit dem Heizleiter in Reihe geschaltet. Der Einbau eines Thermostaten in der Nähe des Trägers oder auf dem zu beheizenden Spiegelglas erfordert viel Bauraum, der weder in einem Innenspiegel noch in einem Außenspiegel moderner Bauart vorhanden ist. Außerdem besitzt ein Thermostat den Nachteil, daß er bisweilen mit einigen Grad K Abweichung von den eingestellten Temperatur-Schaltpunkten schaltet. Dieser Nachteil fällt besonders dann ins Gewicht, wenn der Abstand der Temperaturen, bei denen der Thermostat schalten soll, nur wenige Grad K betragen soll.In this device known from German Offenlegungsschrift 26 45 231, a thermostat is connected in series with the heating conductor. The installation of a thermostat near the support or on the mirror glass to be heated requires a lot of space, which is neither in an interior mirror nor in an exterior mirror of modern design. In addition, a thermostat has the disadvantage that it sometimes switches with a deviation of a few degrees K from the set temperature switching points. This disadvantage is particularly important when the distance between the temperatures at which the thermostat is to switch should only be a few degrees K.

Der Erfindung liegt daher die Aufgabe zugrunde, eine elektrische Heizeinrichtung für ein Spiegelglas eines Kfz-Spiegels zu schaffen, deren Temperaturregeleinrichtung wenig Platz beansprucht und genauer bei den eingestellten Temperaturen ein- oder ausschaltet.The invention is therefore based on the object of providing an electrical heating device for a mirror glass of a motor vehicle mirror, the temperature control device of which takes up little space and more precisely switches on or off at the set temperatures.

Dazu ist bei der eingangs genannten elektrischen Heizeinrichtung erfindungsgemäß vorgesehen, daß mit dem Widerstand, dessen Widerstandswert sich mit der Temperatur kontinuierlich ändert, ein Stellsignal gebildet wird, welches einen den Stromfluß durch den Heizleiter beeinflussenden Halbleiter-Schalter steuert. Durch die analoge Erfassung der Temperatur wird ein wesentlich feinfühligeres Ein- und Ausschalten des Stromflusses durch den Heizleiter erreicht, so daß das Temperaturintervall, innerhalb dessen der Heizleiter von Heizstrom durchflossen ist, auf wenige Grad K eingeengt werden kann. Dabei kann der Widerstand einen positiven oder alternativ auch einen negativen Temperaturkoeffizienten aufweisen.For this purpose, it is provided according to the invention in the aforementioned electric heating device that an actuating signal is formed with the resistor, the resistance value of which changes continuously with temperature, which controls a semiconductor switch influencing the current flow through the heating conductor. Through the analog detection of the temperature, a much more sensitive switching on and off of the current flow through the heating conductor is achieved, so that the temperature interval within which heating current flows through heating current to a few degrees K. can be restricted. The resistance can have a positive or alternatively a negative temperature coefficient.

In zweckmäßiger Ausgestaltung der Erfindung empfiehlt sich eine rückgekoppelte, zweistufige Verstärkerschaltung, deren Steuereingang das Stellsignal zugeführt ist und deren zweite Stufe der Halbleiter-Schalter, vorteilhafterweise ein V-Mos-­Feldeffekttransistor, bildet.In an expedient embodiment of the invention, a feedback, two-stage amplifier circuit is recommended, the control input of which is supplied with the control signal and the second stage of which is the semiconductor switch, advantageously a V-Mos field effect transistor.

Als besonders direkte Beeinflussung des Stromflusses durch den Heizleiter empfiehlt sich eine Reihenschaltung aus diesem und dem Halbleiter-Schalter.A series connection of this and the semiconductor switch is recommended as a particularly direct influence on the current flow through the heating conductor.

Das Stellsignal kann in einfacher Weise dadurch gebildet werden, daß der ersten Stufe der Verstärkerschaltung eine Reihenschaltung aus dem Widerstand und einem weiteren, temperaturunabhängigen Widerstand parallel geschaltet ist, wobei der Verknüpfungspunkt zwischen Widerstand und weiterem Widerstand mit dem Steuereingang der Verstärkerschaltung verbunden ist. Die mit dem Steuereingang verbundene, hochohmige Rückkoppelung wird zweckmäßig am Verknüpfungspunkt zwischen Heizleiter und Halbleiterschalter abgegriffen. Eine besonders feinfühlige Einstellung der Schalttemperaturen wird erreicht, wenn in Weiterbildung der Erfindung das Verhältnis der Widerstandswerte des Widerstandes zu dem weiteren Widerstand und zu dem in der Rückkoppelung vorgesehenen dritten Widerstand sich etwa wie 10:1:100 verhält. Wenn in bevorzugter Ausgestaltung der Erfindung die Temperaturregeleinrichtung auf einer kleinen Platine aufgebaut ist, genügt es zur Regelung der Temperatur des Spiegelglases, wenn der Widerstand mit Abstand sowohl zum Träger als auch zum Spiegelglas auf der Platine gehalten ist. Wenn der Widerstand auf der dem Träger und dem Spiegelglas abgewandten Seite der Platine gehalten ist, kann die thermische Ankoppelung zweckmäßig durch eine in der Platine unterhalb des Widerstandes vorgesehene Öffnung hergestellt werden.The control signal can be formed in a simple manner in that the first stage of the amplifier circuit is connected in parallel from the resistor and a further, temperature-independent resistor, the connection point between the resistor and another resistor being connected to the control input of the amplifier circuit. The high-impedance feedback connected to the control input is expediently tapped at the connection point between the heating conductor and the semiconductor switch. A particularly sensitive setting of the switching temperatures is achieved if, in a further development of the invention, the ratio of the resistance values of the resistor to the further resistor and to the third resistor provided in the feedback behaves approximately as 10: 1: 100. If, in a preferred embodiment of the invention, the temperature control device is constructed on a small circuit board, it is sufficient to regulate the temperature of the mirror glass if the resistance is kept on the circuit board both at a distance from both the carrier and the mirror glass. If the resistor is held on the side of the board facing away from the carrier and the mirror glass, the thermal coupling can expediently be produced through an opening provided in the board below the resistor.

Bevorzugte Ausgestaltungen der Erfindung sind in den Unteransprüchen angegeben.Preferred embodiments of the invention are specified in the subclaims.

Die Erfindung wird nachstehend anhand des in der beigefügten Zeichnung dargestellten Ausführungsbeispiels im einzelnen beschrieben. Es zeigen:

  • Fig. 1 eine Ansicht einer Spiegelglasträgerplatte von hinten mit abgedeckter Temperaturregeleinrichtung;
  • Fig. 2 einen Schnitt durch die Spiegelglasträgerplatte gemäß Fig.2 längs der Linie A - A;
  • Fig. 3 eine Heizfolie mit Temperaturregeleinrichtung;
  • Fig. 4 ein schematisches Schaltungsdiagramm der elektronischen Temperaturregeleinrichtung.
The invention is described below with reference to the embodiment shown in the accompanying drawings. Show it:
  • Figure 1 is a view of a mirror glass support plate from behind with covered temperature control device.
  • 2 shows a section through the mirror glass carrier plate according to FIG. 2 along the line AA;
  • 3 shows a heating foil with a temperature control device;
  • Fig. 4 is a schematic circuit diagram of the electronic temperature control device.

Die in Fig. 1 und 2 dargestellte Spiegelglasträgerplatte 26 kann mittels eines Befestigungsringes an einer Spiegelhalterung eines Kraftfahrzeug-Außenspiegels in der Weise befestigt werden, wie das in der deutschen Patentschrift 29 07 433 beschrieben ist. Für die konstruktive Gestaltung der Spiegelglasträgerplatte 26 wird daher auf diese Druckschrift Bezug genommen. Wie dort beschrieben, besitzt die Spiegelglasträgerplatte 26 eine zentrale Öffnung 19, durch welche ein doppelseitiges Klebeband 18 sichtbar wird, mit dessen Hilfe das Spiegelglas 20 auf die in Fig. 1 nicht erkennbare Vorderseite der Spiegelglasträgerplatte 26 aufgeklebt ist. Beiderseits der Öffnung 19 weist die Spiegelglasträgerplatte 26 zwei gegenüberliegende ebene Flächenstücke 16, 17 auf, von denen das Flächenstück 16 bei Einbau der Spiegelglasträgerplatte 26 in einen Kfz-Außenspiegel näher am Fahrzeug liegt als der Bereich 17.The mirror glass support plate 26 shown in FIGS. 1 and 2 can be fastened to a mirror holder of a motor vehicle exterior mirror by means of a fastening ring in the manner described in German patent specification 29 07 433. For the structural design of the mirror glass support plate 26, reference is therefore made to this document. As described there, the mirror glass carrier plate 26 has a central opening 19 through which a double-sided adhesive tape 18 is visible, with the aid of which the mirror glass 20 is glued onto the front side of the mirror glass carrier plate 26 which cannot be seen in FIG. 1. On both sides of the opening 19, the mirror glass carrier plate 26 has two opposite flat surface pieces 16, 17, of which the surface piece 16 is closer to the vehicle than the region 17 when the mirror glass carrier plate 26 is installed in a motor vehicle exterior mirror.

Aus dem Flächenbereich 16 ist eine haubenartige Ausformung 29 aus der Kunststoff-Glasträgerplatte 26 ausgebildet, welche eine im ganzen mit 24 bezeichnete elektronische Temperaturregeleinrichtung beherbergt. Aus Schlitzen der Haube 29 stehen Anschlußfahnen 21, 22 nach außen vor, auf welche mit den Polen der Fahrzeugbatterie verbindbare Anschlußstecker aufgesteckt werden können.From the surface area 16, a hood-like formation 29 is formed from the plastic glass carrier plate 26, which has an electronic temperature control device designated as a whole by 24 houses. From the slots in the hood 29 there are connecting lugs 21, 22 projecting outwards, onto which connecting plugs which can be connected to the poles of the vehicle battery can be attached.

Die elektronische Temperaturregeleinrichtung 24 ist Bestandteil einer im ganzen mit 15 bezeichneten Heizeinrichtung für das Spiegelglas 20, welche in Fig. 3 dargestellt ist. Die Heizeinrichtung 15 weist einen elektrisch isolierenden plattenförmigen Träger 27 auf, auf welchen ein Heizelement 2 in Form von Leiterbahnschlangen, wie in Fig. 3 dargestellt, aufgebracht ist. Auf dem Träger 27 ist an einer Seite eine Platine 23 befestigt, auf welcher die Temperaturregeleinrichtung 24 aufgebaut ist. Der Träger 27 wird zwischen das Spiegelglas 20 und die Vorderseite der Spiegelglasträgerplatte 26 so eingeklebt, daß die Platine 23 in der Haube 29 beherbergt ist. Der Träger 27, der beispielsweise aus einer 0,3 mm starken Folie besteht, ist in Fig. 2 nicht gesondert eingezeichnet. Das Heizelement 2 ist so ausgelegt, daß es bei einer angelegten Gleichspannung von 12 Volt eine Heizleistung von 20 Watt erbringen kann.The electronic temperature control device 24 is part of a heating device for the mirror glass 20, designated as a whole by 15, which is shown in FIG. 3. The heating device 15 has an electrically insulating plate-shaped carrier 27, on which a heating element 2 in the form of conductor track coils, as shown in FIG. 3, is applied. On one side of the carrier 27, a circuit board 23 is fastened, on which the temperature control device 24 is constructed. The carrier 27 is glued between the mirror glass 20 and the front of the mirror glass carrier plate 26 so that the board 23 is housed in the hood 29. The carrier 27, which consists for example of a 0.3 mm thick film, is not shown separately in FIG. 2. The heating element 2 is designed so that it can provide a heating power of 20 watts with an applied DC voltage of 12 volts.

Gemäß dem in Fig. 4 dargestellten Schaltungsdiagramm der Temperaturregeleinrichtung ist der Anschlußkontakt 21 mit dem positiven Spannungspol der Fahrzeugbatterie von 12 Volt und der Anschlußkontakt 22 mit dem negativen Pol der Batterie verbunden. Zwischen den Anschlußkontakten 21, 22 liegt eine Reihenschaltung aus dem Heizelement 2, das praktisch nur Ohm'schen Widerstand besitzt, und der Drain-Source-Strecke eines V-Mos-­Feldeffekttransistors 4. Ferner ist mit dem spannungsführenden Anschlußkontakt 21 eine Reihenschaltung aus einem ersten Widerstand von beispielsweise 1 Kiloohm und einer Zenerdiode 5 zwecks Spannungsstabilisierung an deren Verknüpfungspunkt 14 verbunden, wobei das freie Ende der Zenerdiode auf dem Potential des Anschlußstiftes 22 liegt. Zwischen dem Verknüpfungspunkt 14 und dem Potential des Anschlußstiftes 22 liegt eine Reihenschaltung aus einem Kollektorwiderstand 8 und der Kollektor-Emitter-Strecke eines npn-Transistors 3. Der Emitter des Transistors 3 liegt auf dem Potential des Anschlußstiftes 22. Das Gate des Feldeffekttransistors 4 ist mit dem Kollektoranschluß des Transistors 3 verbunden. Am Verknüpfungspunkt 14 liegt schließlich noch eine weitere Reihenschaltung aus einem temperaturabhängigen Widerstand 1 und einem im wesentlichen temperaturunabhängigen Widerstand 7, dessen freies Ende auf dem Potential des Anschlußstifes 22 liegt. Der Verknüpfungspunkt 6 der Widerstände 1 und 7 liegt einerseits am Gate des Transistors 3 und andererseits über den Rückkoppelungswiderstand 9 an dem Verknüpfungspunkt zwischen Heizelement 2 und Feldeffektransistor 4. In der Schaltung gemäß Fig. 4 besitzt der Widerstand 1 einen negativen Temperaturkoeffizienten. Das Verhältnis der Ohm'schen Widerstandswerte des Widerstandes 1, des weiteren Widerstandes 7 sowie des Rückkopplungswiderstandes 9 beträgt ungefähr 10:1:100. Die aus einer ersten Stufe mit dem Transistor 3 und einer zweiten Stufe mit dem Feldeffekttransistor gebildete, rückgekoppelte Verstärkerschaltung wird im Großsignalbetrieb gefahren, so daß der Transistor 3 im wesentlichen ein Schmitt-Trigger-Verhalten zeigt und der Feldeffekttransistor als Leistungsschalter arbeitet. Das Potential am Schaltungspunkt 6 wird analog vom Widerstandwert des Widerstandes 1 bestimmt, der sich mit der vom Widerstand 1 erfaßten Temperatur ändert. Damit steht am Schaltungspunkt 6 ein analoges Stellsignal, welches dem Eingang der Verstärkerschaltung zugeführt wird. Man erreicht dadurch bezogen auf die vom Kaltleiterwiderstand 1 erfaßte Temperatur ein sehr genaues Ein- bzw. Ausschalten des Stromes durch den Feldeffekttransistor 4 und damit durch das Heizelement 2.According to the circuit diagram of the temperature control device shown in FIG. 4, the connection contact 21 is connected to the positive voltage pole of the vehicle battery of 12 volts and the connection contact 22 is connected to the negative pole of the battery. Between the connection contacts 21, 22 there is a series connection of the heating element 2, which has practically only ohmic resistance, and the drain-source path of a V-Mos field-effect transistor 4. Furthermore, with the voltage-carrying connection contact 21 there is a series connection of a first Resistance of, for example, 1 kilohm and a Zener diode 5 are connected at the junction point 14 for the purpose of voltage stabilization, the free end of the Zener diode being at the potential of the pin 22. Between the node 14 and the potential of the pin 22 is a series connection of a collector resistor 8 and the collector-emitter path of an npn transistor 3. The emitter of the transistor 3 is on the Potential of the pin 22. The gate of the field effect transistor 4 is connected to the collector terminal of the transistor 3. Finally, at the junction 14 there is a further series circuit comprising a temperature-dependent resistor 1 and an essentially temperature-independent resistor 7, the free end of which is at the potential of the connecting pin 22. The connection point 6 of the resistors 1 and 7 is on the one hand at the gate of the transistor 3 and on the other hand via the feedback resistor 9 at the connection point between the heating element 2 and the field effect transistor 4. In the circuit according to FIG. 4, the resistor 1 has a negative temperature coefficient. The ratio of the ohmic resistance values of the resistor 1, the further resistor 7 and the feedback resistor 9 is approximately 10: 1: 100. The feedback amplifier circuit formed from a first stage with transistor 3 and a second stage with field effect transistor is operated in large signal mode, so that transistor 3 essentially exhibits a Schmitt trigger behavior and the field effect transistor operates as a power switch. The potential at node 6 is determined analogously by the resistance value of resistor 1, which changes with the temperature detected by resistor 1. There is thus an analog control signal at circuit point 6, which is fed to the input of the amplifier circuit. In this way, based on the temperature detected by the PTC resistor 1, a very precise switching on or off of the current through the field effect transistor 4 and thus through the heating element 2 is achieved.

Die Schaltung arbeitet auch in der beschriebenen Weise mit einem Heißleiter, dessen Widerstandswert also einen positiven Temperaturgang besitzt. Der Heizleiter muß dann allerdings anstelle des weiteren Widerstandes 7 und der weitere Widerstand anstelle des Kaltleiters 1 geschaltet werden.The circuit also works in the manner described with a thermistor, the resistance value of which therefore has a positive temperature response. The heating conductor must then be switched instead of the additional resistor 7 and the additional resistor instead of the PTC thermistor 1.

Wie man aus Fig. 2 und 3 erkennt, sitzt der Widerstand 1 auf der dem Träger 27 sowie dem Spiegelglas 20 abgewandten Seite der Platine 23. Um die thermische Ankoppelung des Widerstandes 1 an den Träger 27 oder das Spiegelglas 20 zu verbessern, ist in die Platine 23 unter dem Widerstand 1 eine Durchgangsöffnung eingebracht. Die vom Widerstand erfaßte Temperatur folgt daher mit Verzögerung der Temperatur des Trägers 27 und des Spiegelglases 20.As can be seen from FIGS. 2 and 3, the resistor 1 is located on the side of the carrier 27 and the mirror glass 20 facing away from the Circuit board 23. In order to improve the thermal coupling of the resistor 1 to the carrier 27 or the mirror glass 20, a through opening is introduced into the circuit board 23 under the resistor 1. The temperature detected by the resistor therefore follows the temperature of the carrier 27 and the mirror glass 20 with a delay.

Es versteht sich, daß die Temperaturregeleinrichtung 24 statt wie in Fig. 1 dargestellt auf dem Flächenabscnitt 16 auch auf dem Flächenabschnitt 17 zwischen Spiegelglas 20 und Glasträgerplatte 26 untergebracht sein kann, so daß die Temperaturregeleinrichtung 24 nach Einbau der Spiegelglasträgerplatte 26 in einen Außenspiegel am vom Fahrzeug entfernten Ende des Spiegelglases 20 untergebracht ist und damit die äußeren, vom Fahrzeug entfernten, üblicherweise kälteren Bereiche des Spiegelglases temperaturmäßig erfaßt. Bei Verwendung der in Fig. 4 dargestellten Schaltung läßt sich der Einschaltpunkt der Spiegelheizung durch entsprechende Dimensionierung des Widerstandnetzwerkes auf 27° Celsius und die Ausschalttemperatur der Spiegelheizung auf 30° Celsius fest einstellen.It goes without saying that the temperature control device 24 can be accommodated on the surface section 16 between the mirror glass 20 and the glass support plate 26 instead of the surface section 16, as shown in FIG. 1, so that the temperature control device 24 after installation of the mirror glass support plate 26 in an outside mirror on the vehicle distal end of the mirror glass 20 is housed and thus the outer, removed from the vehicle, usually colder areas of the mirror glass in terms of temperature. When using the circuit shown in FIG. 4, the switch-on point of the mirror heater can be set to 27 ° Celsius by appropriate dimensioning of the resistance network and the switch-off temperature of the mirror heater to 30 ° Celsius.

Claims (11)

1. Elektrische Heizeinrichtung für ein Spiegelglas eines Kfz-­Spiegels mit einem auf einen Träger aufgebrachten Heizleiter und einer Temperaturregeleinrichtung, welche einen nahe dem Träger angeordneten temperaturabhängigen Widerstand aufweist, dadurch gekennzeichnet, daß mit dem Widerstand (1) ein Stellsignal gebildet wird, welches einen den Stromfluß durch den Heizleiter (2) beeinflußenden Halbleiter-Schalter (4) steuert.1. Electric heating device for a mirror glass of a motor vehicle mirror with a heating conductor applied to a carrier and a temperature control device which has a temperature-dependent resistor arranged near the carrier, characterized in that an actuating signal is formed with the resistor (1), which is a Current flow through the heat conductor (2) influencing semiconductor switch (4) controls. 2. Einrichtung nach Anspruch 1, dadurch gekennzeichnet, daß der Heizleiter (2) mit dem Halbleiter-Schalter (4) in Reihe geschaltet ist.2. Device according to claim 1, characterized in that the heating conductor (2) with the semiconductor switch (4) is connected in series. 3. Einrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Halbleiterschalter die zweite Stufe einer rückgekoppelten zweistufigen Verstärkerschaltung (3, 4) ist, deren Steuereingang das Stellsignal zugeführt ist.3. Device according to claim 1 or 2, characterized in that the semiconductor switch is the second stage of a feedback two-stage amplifier circuit (3, 4), the control input of which is supplied with the control signal. 4. Einrichtung nach Anspruch 3, dadurch gekennzeichnet, daß der ersten Stufe (3) der Verstärkerschaltung eine Reihenschaltung aus dem Widerstand (1) sowie einem weiteren im wesentlichen temperaturunabhängigen Widerstand (7) parallel geschaltet ist, wobei der Verknüpfungspunkt des Widerstandes (1) sowie des weiteren Widerstandes (7) mit dem Steuereingang (6) der Verstärkerschaltung verbunden ist.4. Device according to claim 3, characterized in that the first stage (3) of the amplifier circuit, a series circuit comprising the resistor (1) and a further substantially temperature-independent resistor (7) is connected in parallel, the node of the resistor (1) and the further resistor (7) is connected to the control input (6) of the amplifier circuit. 5. Einrichtung nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß der Widerstand (1) einen positiven Temperaturkoeffizienten besitzt.5. Device according to one of the preceding claims, characterized in that the resistor (1) has a positive temperature coefficient. 6. Einrichtung nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß der Widerstand (1) einen negativen Temperaturkoeffizienten besitzt.6. Device according to one of claims 1 to 5, characterized in that the resistor (1) has a negative temperature coefficient. 7. Einrichtung nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß der Halbleiter-Schalter (4) ein V-Mos-­ Feldeffekttransistor ist.7. Device according to one of the preceding claims, characterized in that the semiconductor switch (4) is a V-Mos Field effect transistor is. 8. Einrichtung nach einem der Ansprüche 2 bis 7, dadurch gekennzeichnet, daß vom Verknüpfungspunkt zwischen Heizleiter (2) und Halbleiterschaltung (4) eine Rückkoppelungsleitung zum Steuereingang gelegt ist, welche einen dritten Widerstand (9) enthält.8. Device according to one of claims 2 to 7, characterized in that from the point of connection between the heating conductor (2) and the semiconductor circuit (4) a feedback line to the control input is placed, which contains a third resistor (9). 9. Einrichtung nach Anspruch 8, dadurch gekennzeichnet, daß das Widerstandsverhältnis des Widerstandes (1) zum weiteren Widerstand (7) sowie zum dritten Widerstand (9) etwa wie 10:1:100 beträgt.9. Device according to claim 8, characterized in that the resistance ratio of the resistor (1) to the further resistor (7) and to the third resistor (9) is approximately as 10: 1: 100. 10. Einrichtung nach einem der Ansprüche 3 bis 9, dadurch gekennzeichnet, daß der ersten Stufe (3) der Verstärkerschaltung sowie der den Widerstand (1) enthaltenden Reihenschaltung eine Überspannungssicherung (5, 10) vorgeschaltet ist, welche eine Zenerdiode (5) aufweist.10. Device according to one of claims 3 to 9, characterized in that the first stage (3) of the amplifier circuit and the series circuit containing the resistor (1) is connected upstream of an overvoltage protection device (5, 10) which has a zener diode (5). 11. Einrichtung nach einem der vorstehenden Ansprüche dadurch gekennzeichnet, daß die Temperaturregeleinrichtung (24) auf einer auf dem Träger (27) befestigten Platine (23) untergebracht oder das Layout mit auf der Heizfolie aufgebracht ist und unter einer haubenförmigen, außermittigen Ausformung (29) einer Spiegelglasträgerplatte (26) beherbergt ist.11. Device according to one of the preceding claims, characterized in that the temperature control device (24) on a support (27) attached to the board (23) is housed or the layout is applied to the heating foil and under a hood-shaped, eccentric shape (29) a mirror glass support plate (26) is housed.
EP19900109114 1989-07-21 1990-05-15 Electrical heating device for the reflective surface of a vehicle rearview mirror Withdrawn EP0408853A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19893924040 DE3924040A1 (en) 1989-07-21 1989-07-21 ELECTRIC HEATING DEVICE FOR A MIRROR GLASS OF A MOTOR VEHICLE MIRROR
DE3924040 1989-07-21

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EP0408853A2 true EP0408853A2 (en) 1991-01-23
EP0408853A3 EP0408853A3 (en) 1992-01-15

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DE19906531A1 (en) * 1999-02-17 2000-08-31 Volkswagen Ag Multifunction switch for engaging car external rear view mirrors with mirror positioning switch, has segmented diaphragm in which segments operate as actuating faces with additional switching functions
US6917019B2 (en) 2001-04-25 2005-07-12 Brose Fahrzeugteile Gmbh & Co. Kg, Coburg Heating and method for controlling heating of a functional unit on a motor vehicle
CN103818353A (en) * 2014-02-20 2014-05-28 中通客车控股股份有限公司 Electrothermal defogging rearview mirror
EP3308075A4 (en) * 2015-06-15 2019-07-03 J.W. Speaker Corporation Lens heating systems and methods for an led lighting system
US11019689B2 (en) 2015-06-15 2021-05-25 J.W. Speaker Corporation Lens heating systems and methods for an LED lighting system
WO2022043183A1 (en) * 2020-08-28 2022-03-03 Agc Glass Europe Glazing thermal sensor

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DE19509153A1 (en) * 1995-03-14 1996-09-19 Bayerische Motoren Werke Ag Shaped body with heating device, in particular exterior rear view mirror of a motor vehicle
DE19938396B4 (en) * 1999-08-05 2006-08-10 Brose Fahrzeugteile Gmbh & Co. Kommanditgesellschaft, Coburg Motor vehicle mirror
DE10058434C2 (en) * 2000-11-24 2003-12-04 Audi Ag Method and device for controlling the heating of an exterior mirror
DE10104955B4 (en) * 2001-02-03 2008-10-02 Behr-Hella Thermocontrol Gmbh Sensor for detecting the temperature in the interior of a vehicle
JP2021117140A (en) * 2020-01-28 2021-08-10 パイオニア株式会社 Sensor device, housing, and cover part

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DE1919941A1 (en) * 1969-04-19 1970-11-05 Eberle Werke Kg Resistance bridge with electronic threshold switch
DE1957150A1 (en) * 1969-11-13 1971-05-19 Siemens Ag Continuously regulating thermostat
DE2211759A1 (en) * 1972-03-10 1973-09-20 Siemens Ag CIRCUIT ARRANGEMENT FOR CONTINUOUS TEMPERATURE CONTROL
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19906531A1 (en) * 1999-02-17 2000-08-31 Volkswagen Ag Multifunction switch for engaging car external rear view mirrors with mirror positioning switch, has segmented diaphragm in which segments operate as actuating faces with additional switching functions
US6917019B2 (en) 2001-04-25 2005-07-12 Brose Fahrzeugteile Gmbh & Co. Kg, Coburg Heating and method for controlling heating of a functional unit on a motor vehicle
CN103818353A (en) * 2014-02-20 2014-05-28 中通客车控股股份有限公司 Electrothermal defogging rearview mirror
CN103818353B (en) * 2014-02-20 2016-05-11 中通客车控股股份有限公司 A kind of electric heated defrosting rearview mirror
EP3308075A4 (en) * 2015-06-15 2019-07-03 J.W. Speaker Corporation Lens heating systems and methods for an led lighting system
US11019689B2 (en) 2015-06-15 2021-05-25 J.W. Speaker Corporation Lens heating systems and methods for an LED lighting system
WO2022043183A1 (en) * 2020-08-28 2022-03-03 Agc Glass Europe Glazing thermal sensor

Also Published As

Publication number Publication date
EP0408853A3 (en) 1992-01-15
DE3924040C2 (en) 1993-09-16
DE3924040A1 (en) 1991-01-24

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