EP0786714B1 - Method and apparatus for adjusting the intensity of a current or voltage controlled lighting means for rear lighting of a display device especially for motor vehicles - Google Patents

Method and apparatus for adjusting the intensity of a current or voltage controlled lighting means for rear lighting of a display device especially for motor vehicles Download PDF

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Publication number
EP0786714B1
EP0786714B1 EP96112912A EP96112912A EP0786714B1 EP 0786714 B1 EP0786714 B1 EP 0786714B1 EP 96112912 A EP96112912 A EP 96112912A EP 96112912 A EP96112912 A EP 96112912A EP 0786714 B1 EP0786714 B1 EP 0786714B1
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EP
European Patent Office
Prior art keywords
brightness
luminous means
microcomputer
display
current
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Revoked
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EP96112912A
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German (de)
French (fr)
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EP0786714A2 (en
EP0786714A3 (en
Inventor
Henry Strobel
Jörg Jung
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Mannesmann VDO AG
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Siemens AG
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    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05FSYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10Regulating voltage or current
    • G05F1/46Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G05F1/565Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406Control of illumination source

Definitions

  • the invention relates to a method for adjusting the brightness of a current or voltage-controlled lamps for backlighting a display, at which the control voltage or the control current of the illuminant is set is, as well as a display device of a motor vehicle that has a backlight with a current or voltage controlled lamp, whose brightness is adjustable.
  • LEDs it is also common to use LEDs to backlight individual control buttons. This serves either to display the function of the button or to serve the user to help you find the right key.
  • LEDs or lamps on the other hand, have very wide ranges in terms of their brightness on, so that the display brightness of is not available.
  • the lamps are then different Series resistors are used to provide an even display brightness to achieve.
  • a display system with an LCD is known from EP 0 572 207 A2 is backlit by a light source.
  • the brightness of the light source will determined by an internal photodetector and the measured value for brightness control used.
  • US 5,416,385 is also a device and a Method known with which the light intensity of a light source can be influenced can.
  • the invention is therefore based on the object of a method or a display device to indicate at which the backlighting does not require a lot of logistics is adjustable for displays with a closely tolerated brightness.
  • the object is achieved by a method according to claim 1 or a display device according to claim 6 solved.
  • the advantage of the invention is that the brightness only at the end of the tape of the lamp to the corresponding tolerances with otherwise the same hardware is adjusted. Possible errors during assembly are prevented and the logistics effort is reduced to a minimum
  • the control voltage or the control current of the illuminant is advantageous determined with the help of an electronic calculator that the Correction factor takes from a data memory in which an assignment the brightness of the lamp to the corresponding correction factor is.
  • the actual brightness of the lamp is measured and the corresponding measured value is fed to the electronic computer.
  • one of the middle ones can be added to the electronic computer expected brightness of the lamp is supplied with the corresponding value become.
  • the brightness of the lamp is always in the middle of the tolerance field is set. All others affect the brightness Sizes are eliminated.
  • the information provided by the electronic computer Control signal is a pulse signal whose pulse width depends on the brightness of the lamp is set.
  • An advantageous embodiment of the invention is that a Series connection of the bulbs leads to a fixed voltage on the one hand and on the other hand is connected to a series resistor.
  • the series resistor is connected to an output of a first microcomputer via a transistor, which has a programmable memory, where on the brightness signal is present at an input of the microcomputer.
  • the programmable However, memory can also be arranged outside the microcomputer his.
  • the first microcomputer is arranged in the display control unit.
  • the first microcomputer advantageously has a diagnostic interface by means of which the first microcomputer with a second microcomputer can be connected, which controls the brightness measurement.
  • the second microcomputer is advantageously a test computer.
  • Figure 1 is the usual setting of the brightness of a backlight represented by buttons.
  • Three LEDs 1, 2, 3 are with a series resistor 4 between terminal 58g of the motor vehicle and ground connected. By installing LEDs and series resistor, the brightness the backlight is set once and can no longer Getting corrected.
  • FIG. 2 is now a transistor between the series resistor 4 and ground 5 switched, the base of which is connected to the input 14 of a microcomputer 7 is connected.
  • the microcomputer 7 is both with bus lines a non-volatile memory 8 (EEPROM) as well as with a diagnostic interface 9 connected.
  • the microcomputer 7, memory 8 and interface 9 are arranged in a control device 6, which in turn in a Display device 10 for controlling an LCD display 11 is included.
  • the light emitting diodes 1, 2 and 3 are placed behind the LCD display 11.
  • any LCD's 1, 2 can now be produced in the manufacture of the display device 10 and 3 are installed.
  • the Luminosity of LEDs 1, 2 and 3 in a tape end test using a Test computer 12, preferably an existing production computer, can be set.
  • the brightness emitted by the LEDs is measured by a light meter 13 measured and the measured value via an A / D converter to the test computer Given 12.
  • This test computer 12 is also with the diagnostic interface 9 of the control unit 6 connected, which is simply by a diagnostic connector can be implemented.
  • the digitized measured brightness value is given to the microcomputer 7 of the control device 6.
  • the PWM signal is thus fixed and remains for the life of the LED's received.
  • the correction values stored in EEPROM 8 can be based on tables be determined. If there is a high storage capacity, the dependency is the PWM signal from the brightness is also possible in the form of characteristic maps, which determined a higher accuracy of the adaptation to the point Allow lighting characteristics of the LEDs.
  • search lighting which serves the user to find To lighten a button, it makes sense that the LED's or lamps according to their measured brightness fluctuations from the microcomputer 7 assigned to a fixed class stored in EEPROM 8 become. If the brightness value falls into this class, the transistor 5 is activated, otherwise the transistor 5 is not activated.
  • resistor 15 is switched on via transistor 5 when a signal is present shorted.
  • the LEDs are so-called low-side switches on one constant voltage or current source.
  • the one controlled by the microprocessor 7 Transistor 5 is connected to the in a manner known per se Power source connected.
  • the clock signal leads to a Voltage change, which is a change in brightness of the LED's draws.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Instrument Panels (AREA)
  • Arrangements Of Lighting Devices For Vehicle Interiors, Mounting And Supporting Thereof, Circuits Therefore (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Description

Die Erfindung betrifft ein Verfahren zur Einstellung der Helligkeit eines stromoder spannungsgesteuerten Leuchtmittels zur Hinterleuchtung einer Anzeige, bei dem die Steuerspannung oder der Steuerstrom des Leuchtmittels eingestellt wird, sowie ein Anzeigegerät eines Kraftfahrzeugs, das eine Hintergrundbeleuchtung mit einem strom- oder spannungsgesteuerten Leuchtmittel aufweist, dessen Helligkeit einstellbar ist.The invention relates to a method for adjusting the brightness of a current or voltage-controlled lamps for backlighting a display, at which the control voltage or the control current of the illuminant is set is, as well as a display device of a motor vehicle that has a backlight with a current or voltage controlled lamp, whose brightness is adjustable.

In modernen Bediengeräten werden zur Anzeige von Funktionszuständen, Sollund Istwerten sehr häufig LCD's eingesetzt. Alle LCD's haben eine Hinterleuchtung, um die Ablesbarkeit bei allen äußeren Lichtverhältnissen sicherzustellen. Diese Hinterleuchtung wird durch Lampen oder LED's realisiert.In modern operator panels, the display of functional states, target and LCDs are used very often for actual values. All LCD's have backlighting, to ensure readability in all external lighting conditions. This backlighting is realized by lamps or LEDs.

Auch ist es üblich, LED's zur Hinterleuchtung einzelner Bedientasten zu nutzen. Dies dient entweder der Funktionsanzeige der Taste oder aber dazu, den Nutzer bei der Suche nach der richtigen Taste zu unterstützen.It is also common to use LEDs to backlight individual control buttons. This serves either to display the function of the button or to serve the user to help you find the right key.

Es besteht daher das Bestreben, ein harmonisches, gleichmäßiges Ausleuchtungserscheinungsbild der Anzeige zu erreichen. Insbesondere in Kraftfahrzeugen sind zu diesem Zwecke für die verschiedenen Anzeigen wie Radio, Klimaanlage, Bordcomputer oder Tachometer Helligkeitswerte in sehr engen Toleranzen vorgeschrieben.There is therefore a desire to have a harmonious, uniform illumination appearance to reach the ad. Especially in motor vehicles are for this purpose for the various displays such as radio, air conditioning, On-board computer or speedometer Brightness values in very tight tolerances required.

LED's oder Lampen hingegen weisen in ihrer Helligkeit sehr große Streubreiten auf, so daß die bei der Kraftfahrzeugherstellung geforderte Anzeigehelligkeit of nicht erreichbar ist.LEDs or lamps, on the other hand, have very wide ranges in terms of their brightness on, so that the display brightness of is not available.

Um die gewünschte Anzeigehelligkeit zu erreichen, ist es bisher üblich, die Leuchtmittel auszumessen und entsprechend ihrer Leuchtstärke in verschiedene Klassen zu selektieren.In order to achieve the desired display brightness, it has so far been common to use the Measure bulbs and according to their luminosity in different To select classes.

Bei der Herstellung der Elektronik werden die Leuchtmittel dann mit unterschiedlichen Vorwiderständen versehen, um eine gleichmäßige Anzeigehelligkeit zu erzielen.When manufacturing the electronics, the lamps are then different Series resistors are used to provide an even display brightness to achieve.

Nachteilig dabei ist, daß zu Beginn der Anzeigenherstellung Leuchtmittel und Vorwiderstände festgelegt sind. Dies ist mit einem sehr hohen logistischen Aufwand verbunden. Auftretende Fehler, z. B. durch den Einbau eines anderen Leuchtmittels oder eines falschen Widerstands können aber nicht ausgeschlossen werden.The disadvantage here is that at the beginning of the display manufacture lamps and Series resistors are set. This is with a very high logistical effort connected. Errors that occur, e.g. B. by installing another Illuminants or a wrong resistor can not be excluded become.

Aus der EP 0 572 207 A2 ist ein Anzeigesystem mit einem LCD bekannt, das von einer Lichtquelle hinterleuchtet wird. Die Helligkeit der Lichtquelle wird durch einen internen Photodetektor bestimmt und der Meßwert zur Helligkeitsregelung herangezogen. Aus der US 5,416,385 ist ebenfalls ein Gerät und ein Verfahren bekannt, mit dem die Lichtintensität einer Lichtquelle beeinflußt werden kann. A display system with an LCD is known from EP 0 572 207 A2 is backlit by a light source. The brightness of the light source will determined by an internal photodetector and the measured value for brightness control used. From US 5,416,385 is also a device and a Method known with which the light intensity of a light source can be influenced can.

Der Erfindung liegt somit die Aufgabe zugrunde, ein Verfahren bzw. ein Anzeigegerät anzugeben, bei welchem ohne hohen logistischen Aufwand die Hintergrundbeleuchtung für Anzeigen mit einer eng tolerierten Helligkeit einstellbar ist.The invention is therefore based on the object of a method or a display device to indicate at which the backlighting does not require a lot of logistics is adjustable for displays with a closely tolerated brightness.

Erfindungsgemäß wird die Aufgabe durch ein Verfahren nach Anspruch 1 bzw. ein Anzeigegerät nach Anspruch 6 gelöst.According to the invention, the object is achieved by a method according to claim 1 or a display device according to claim 6 solved.

Der Vorteil der Erfindung besteht darin, daß erst am Bandende die Helligkeit des Leuchtmittels an die entsprechenden Toleranzen bei sonst gleicher Hardware angepaßt wird. Fehlermöglichkeiten beim Zusammenbau werden unterbunden und der Logistikaufwand auf ein Minimum reduziertThe advantage of the invention is that the brightness only at the end of the tape of the lamp to the corresponding tolerances with otherwise the same hardware is adjusted. Possible errors during assembly are prevented and the logistics effort is reduced to a minimum

Vorteilhafterweise wird die Steuerspannung oder der Steuerstrom des Leuchtmittels mit Hilfe eines elektronischen Rechners bestimmt, der den Korrekturfaktor einem Datenspeicher entnimmt, in welchem eine Zuordnung der Helligkeit des Leuchtmittels zum entsprechenden Korrekturfaktor abgelegt ist. Die tatsächliche Helligkeit des Leuchtmittels wird dabei gemessen und der entsprechende Meßwert dem elektronischen Rechner zugeführt. Alternativ kann dem elektronischen Rechner auch ein der mittleren zu erwartenden Helligkeit des Leuchtmittels entsprechender Wert zugeführt werden.The control voltage or the control current of the illuminant is advantageous determined with the help of an electronic calculator that the Correction factor takes from a data memory in which an assignment the brightness of the lamp to the corresponding correction factor is. The actual brightness of the lamp is measured and the corresponding measured value is fed to the electronic computer. Alternatively, one of the middle ones can be added to the electronic computer expected brightness of the lamp is supplied with the corresponding value become.

Mit Hilfe der Rechnersteuerung wird die Helligkeit des Leuchtmittels immer in die Mitte des Toleranzfeldes eingestellt. Alle weiteren die Helligkeit beeinflussenden Größen werden eliminiert.With the help of the computer control, the brightness of the lamp is always in the middle of the tolerance field is set. All others affect the brightness Sizes are eliminated.

In einer Weiterbildung ist das vom elektronischen Rechner abgegebene Steuersignal ein Impulssignal, dessen Impulsbreite in Abhängigkeit der Helligkeit des Leuchtmittels eingestellt wird.In a further development, the information provided by the electronic computer Control signal is a pulse signal whose pulse width depends on the brightness of the lamp is set.

Eine vorteilhafte Ausführungsform der Erfindung besteht darin, daß eine Reihenschaltung der Leuchtmittel einerseits an eine Festspannung führt und andererseits mit einem Vorwiderstand verbunden ist. Der Vorwiderstand ist über einen Transistor mit einem Ausgang eines ersten Mikrocomputers verbunden, welcher einen programmierbaren Speicher aufweist, wobei an einem Eingang des Mikrocomputers das Helligkeitssignal anliegt. Der programmierbare Speicher kann aber auch außerhalb des Mikrocomputers angeordnet sein.An advantageous embodiment of the invention is that a Series connection of the bulbs leads to a fixed voltage on the one hand and on the other hand is connected to a series resistor. The series resistor is connected to an output of a first microcomputer via a transistor, which has a programmable memory, where on the brightness signal is present at an input of the microcomputer. The programmable However, memory can also be arranged outside the microcomputer his.

Dabei ist der erste Mikrocomputer im Anzeigensteuergerät angeordnet.The first microcomputer is arranged in the display control unit.

Der erste Mikrocomputer weist vorteilhafterweise eine Diagnoseschnittstelle auf, mittels welchem der erste Mikrocomputer mit einem zweiten Mikrocomputer verbindbar ist, der die Helligkeitsmessung steuert.The first microcomputer advantageously has a diagnostic interface by means of which the first microcomputer with a second microcomputer can be connected, which controls the brightness measurement.

Der zweite Mikrocomputer ist vorteilhafterweise ein Prüfrechner.The second microcomputer is advantageously a test computer.

Die Nutzung von an sich vorhandenen Mikrorechnern vereinfacht die Realisierung der Erfindung deutlich. The use of existing microcomputers simplifies the implementation the invention clearly.

Die Erfindung läßt zahlreiche Ausführungsbeispiele zu. Eines davon soll anhand der in der Zeichnung dargestellten Figuren näher erläutert werden.The invention allows numerous exemplary embodiments. One of them should be based on of the figures shown in the drawing are explained in more detail.

Es zeigt

Fig. 1:
Helligkeitseinstellung nach dem Stand der Technik
Fig. 2:
Anordnung zur Einstellung einer LCD-Hinterleuchtung
Fig. 3:
Anordnung zur Einstellung einer Tastenhinterleuchtung als Suchbeleuchtung
It shows
Fig. 1:
State-of-the-art brightness setting
Fig. 2:
Arrangement for setting an LCD backlight
Fig. 3:
Arrangement for setting a key backlight as search lighting

Gleiche Merkmale sind in allen Figuren mit den gleichen Bezugszeichen versehen.Identical features are provided with the same reference symbols in all figures.

Die Erfindung soll nun am Beispiel von Anzeigen in Kraftfahrzeugen näher erläutert werden.The invention will now take the example of displays in motor vehicles are explained.

In Figur 1 ist die bisher übliche Einstellung der Helligkeit einer Hinterleuchtung von Tasten dargestellt. Drei LED's 1, 2, 3 sind mit einem Vorwiderstand 4 zwischen Klemme 58g des Kraftfahrzeuges und Masse geschaltet. Durch die Montage von LED's und Vorwiderstand wird die Helligkeit der Hintergrundbeleuchtung einmalig festgelegt und kann nicht mehr korrigiert werden.In Figure 1 is the usual setting of the brightness of a backlight represented by buttons. Three LEDs 1, 2, 3 are with a series resistor 4 between terminal 58g of the motor vehicle and ground connected. By installing LEDs and series resistor, the brightness the backlight is set once and can no longer Getting corrected.

Gemäß Figur 2 ist nun zwischen den Vorwiderstand 4 und Masse ein Transistor 5 geschaltet, dessen Basis mit dem Eingang 14 eines Mikrocomputers 7 verbunden ist. Der Mikrocomputer 7 ist über Busleitungen sowohl mit einem nichtflüchtigen Speicher 8 (EEPROM) als auch mit einer Diagnoseschnittstelle 9 verbunden. Der Mikrocomputer 7, Speicher 8 und Schnittstelle 9 sind dabei in einem Steuergerät 6 angeordnet, welches wiederum in einem Anzeigegerät 10 zur Steuerung einer LCD-Anzeige 11 enthalten ist.According to Figure 2 is now a transistor between the series resistor 4 and ground 5 switched, the base of which is connected to the input 14 of a microcomputer 7 is connected. The microcomputer 7 is both with bus lines a non-volatile memory 8 (EEPROM) as well as with a diagnostic interface 9 connected. The microcomputer 7, memory 8 and interface 9 are arranged in a control device 6, which in turn in a Display device 10 for controlling an LCD display 11 is included.

In Figur 2 sind dabei nur die zur Erläuterung der Erfindung notwendigen Merkmale dargestellt. In Figure 2 are only those necessary to explain the invention Features shown.

Die Leuchtdioden 1, 2 und 3 sind dabei hinter der LCD-Anzeige 11 plaziert.The light emitting diodes 1, 2 and 3 are placed behind the LCD display 11.

Bei der Herstellung des Anzeigegerätes 10 können nun beliebige LCD's 1, 2 und 3 verbaut werden. Nach Fertigstellung des Anzeigegerätes 10 kann die Leuchtstärke der LED's 1, 2 und 3 in einer Bandendeprüfung mit Hilfe eines Prüfrechners 12, vorzugsweise eines an sich vorhandenen Fertigungsrechners, eingestellt werden.Any LCD's 1, 2 can now be produced in the manufacture of the display device 10 and 3 are installed. After completion of the display device 10, the Luminosity of LEDs 1, 2 and 3 in a tape end test using a Test computer 12, preferably an existing production computer, can be set.

Dazu wird die von den LED's ausgesandte Helligkeit von einem Lichtmeßgerät 13 gemessen und der Meßwert über einen A/D-Wandler an den Prüfrechner 12 gegeben. Dieser Prüfrechner 12 ist weiterhin mit der Diagnoseschnittstelle 9 des Steuergerätes 6 verbunden, was einfacherweise durch einen Diagnosestecker realisiert werden kann. Der digitalisierte Helligkeitsmeßwert wird so an den Mikrorechner 7 des Steuergerätes 6 gegeben.For this purpose, the brightness emitted by the LEDs is measured by a light meter 13 measured and the measured value via an A / D converter to the test computer Given 12. This test computer 12 is also with the diagnostic interface 9 of the control unit 6 connected, which is simply by a diagnostic connector can be implemented. The digitized measured brightness value is given to the microcomputer 7 of the control device 6.

Dieser vergleicht den Helligkeitswert mit einer im EEPROM 8 abgelegten Tabelle, wo jedem möglichen Helligkeitswert eine definierte Pulsweite für ein Ansteuersignal des Transistors 5 zugeordnet ist.This compares the brightness value with one stored in EEPROM 8 Table where each possible brightness value has a defined pulse width for one Control signal of the transistor 5 is assigned.

Mit Hilfe dieses am Ausgang 14 des Mikrorechners 7 anliegenden PWM-Signals wird der Transistor 5 getaktet angesteuert, was eine Spannungsänderung an den LED's 1 bis 3 und somit eine Helligkeitsänderung der Leuchtdioden zur Folge hat.With the help of this PWM signal present at the output 14 of the microcomputer 7 the transistor 5 is driven clocked, which causes a change in voltage on LEDs 1 to 3 and thus a change in brightness of the LEDs has the consequence.

Das PWM-Signal ist somit fest eingestellt und bleibt für die Lebensdauer der LED's erhalten.The PWM signal is thus fixed and remains for the life of the LED's received.

Bei einem notwendigen Austausch der Lampen ist es jederzeit möglich, mit Hilfe eines Diagnoserechners auf die beschriebene Art und Weise ein neues Taktverhältnis einzustellen.If the lamps need to be replaced, it is always possible to use With the help of a diagnostic computer in the way described a new one Set the clock ratio.

Die im EEPROM 8 abgelegten Korrekturwerte können anhand von Tabellen ermittelt werden. Bei vorhandener hoher Speicherkapazität ist die Abhängigkeit des PWM-Signals von der Helligkeit auch in Form von Kennfeldern möglich, die eine höhere Genauigkeit der Anpassung an die punktuell ermittelte Leuchtcharakteristik der LED's ermöglichen.The correction values stored in EEPROM 8 can be based on tables be determined. If there is a high storage capacity, the dependency is the PWM signal from the brightness is also possible in the form of characteristic maps, which determined a higher accuracy of the adaptation to the point Allow lighting characteristics of the LEDs.

Die bislang erläuterte gleitende Anpassung der Helligkeit der Hintergrundbeleuchtung für eine LCD-Anzeige ist auch für die Hinterleuchtung von einzelnen Tasten anwendbar.The previously described sliding adjustment of the brightness of the backlight for an LCD display is also for backlighting individual Buttons applicable.

Bei der sogenannten Suchbeleuchtung, die dazu dient dem Nutzer das Auffinden einer Taste zu erleichtern, bietet es sich an, daß die LED's oder Lampen entsprechend ihrer gemessenen Helligkeitsschwankungen vom Mikrocomputer 7 einer festen, im EEPROM 8 abgespeicherten Klasse zugeordnet werden. Fällt der Helligkeitswert in diese Klasse, wird der Transistor 5 angesteuert, ansonsten unterbleibt die Ansteuerung des Transistors 5.With the so-called search lighting, which serves the user to find To lighten a button, it makes sense that the LED's or lamps according to their measured brightness fluctuations from the microcomputer 7 assigned to a fixed class stored in EEPROM 8 become. If the brightness value falls into this class, the transistor 5 is activated, otherwise the transistor 5 is not activated.

Wie in Figur 3 dargestellt, ist für diese Helligkeitsanpassung eine Widerstandskombination, bestehend aus den Widerständen 4 und 15 notwendig. Der Widerstand 15 wird dabei bei anliegendem Signal über den Transistor 5 kurzgeschlossen.As shown in FIG. 3, a resistance combination is required for this brightness adjustment, consisting of resistors 4 and 15 necessary. Resistor 15 is switched on via transistor 5 when a signal is present shorted.

Es sei noch darauf verwiesen, daß sich das erfindungsgemäße Prinzip auch bei der Funktionsbeleuchtung von Tasten anwenden läßt, die signalisiert, daß eine Taste eingeschaltet ist.It should also be pointed out that the principle according to the invention also applies can be used in the functional lighting of buttons that signals that a button is on.

Dabei liegen die LED's mit sogenannten Low-Side-Schaltem an einer konstanten Spannungs- oder Stromquelle. Der vom Mikroprozessor 7 gesteuerte Transistor 5 wird dabei in an sich bekannter Art und Weise an die Stromquelle angeschlossen. Auch hier führt das Taktsignal zu einer Spannungsänderung, die eine Helligkeitsänderung der LED's nach sich zieht.The LEDs are so-called low-side switches on one constant voltage or current source. The one controlled by the microprocessor 7 Transistor 5 is connected to the in a manner known per se Power source connected. Here too, the clock signal leads to a Voltage change, which is a change in brightness of the LED's draws.

Claims (8)

  1. Method for setting the brightness of a current- or voltage-controlled luminous means for the backlighting of a display, in particular for motor vehicles, in which the control voltage or the control current of the luminous means is set, characterized in that, after the production of the display, in a test step, depending on the brightness of the luminous means, a correction factor is determined, which is taken from a data memory by means of an electronic computer, an assignment of the brightness of the luminous means to the corresponding correction factor being stored in the said data memory, and the control voltage or the control current of the luminous means is fixedly set by means of the correction factor.
  2. Method according to Claim 1, characterized in that the correction factor is determined using a stored table or using stored families of characteristic curves.
  3. Method according to Claims 1 and 2, characterized in that the actual brightness of the luminous means is measured and the corresponding measured value is fed to the electronic computer.
  4. Method according to Claims 1 and 2, characterized in that a value corresponding to the average expected brightness of the luminous means is fed to the electronic computer.
  5. Method according to one of the preceding Claims 2 to 4, characterized in that the control signal output by the electronic computer is a pulse signal whose pulse width is set in a manner dependent on the brightness of the luminous means.
  6. Display unit of a motor vehicle, which has background illumination with a current- or voltage-controlled luminous means whose brightness is adjustable, characterized in that the display unit contains a series circuit of a plurality of luminous means (1-3), which, on the one hand, leads to a fixed voltage and, on the other hand, is connected to a series resistor (4), which is connected via a transistor (5) to an output (14) of a first microcomputer (7), which has a programmable memory (8), in which a table or families of characteristic curves with an assignment of brightness values to correction factors is stored, a correction factor being determined after the production of the display in a test step depending on the brightness of the luminous means (1-3), and the control voltage or the control current of the luminous means (1-2) is fixedly set by means of one of the correction factors.
  7. Display unit according to Claim 6, characterized in that the first microcomputer (7) is arranged in a display control unit (6).
  8. Display unit according to Claim 6 or 7, characterized in that the first microcomputer (7) has a diagnostic interface (9), by means of which the first microcomputer (7) is connected to a second microcomputer (12), which controls the brightness measurement.
EP96112912A 1996-01-27 1996-08-10 Method and apparatus for adjusting the intensity of a current or voltage controlled lighting means for rear lighting of a display device especially for motor vehicles Revoked EP0786714B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19602891A DE19602891A1 (en) 1996-01-27 1996-01-27 Method and arrangement for adjusting the brightness of a current- or voltage-controlled illuminant for backlighting a display, in particular for motor vehicles
DE19602891 1996-01-27

Publications (3)

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EP0786714A2 EP0786714A2 (en) 1997-07-30
EP0786714A3 EP0786714A3 (en) 1998-06-24
EP0786714B1 true EP0786714B1 (en) 2002-11-20

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EP96112912A Revoked EP0786714B1 (en) 1996-01-27 1996-08-10 Method and apparatus for adjusting the intensity of a current or voltage controlled lighting means for rear lighting of a display device especially for motor vehicles

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DE59609885D1 (en) 2003-01-02
EP0786714A2 (en) 1997-07-30
DE19602891A1 (en) 1997-08-07
EP0786714A3 (en) 1998-06-24

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