WO2011070062A1 - Unité d'affichage à diodes électroluminescentes (led) et procédé de commande de diodes électroluminescentes (led) pour affichage - Google Patents

Unité d'affichage à diodes électroluminescentes (led) et procédé de commande de diodes électroluminescentes (led) pour affichage Download PDF

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Publication number
WO2011070062A1
WO2011070062A1 PCT/EP2010/069162 EP2010069162W WO2011070062A1 WO 2011070062 A1 WO2011070062 A1 WO 2011070062A1 EP 2010069162 W EP2010069162 W EP 2010069162W WO 2011070062 A1 WO2011070062 A1 WO 2011070062A1
Authority
WO
WIPO (PCT)
Prior art keywords
led
mode
display
voltage
light
Prior art date
Application number
PCT/EP2010/069162
Other languages
German (de)
English (en)
Other versions
WO2011070062A4 (fr
Inventor
Stefan Fehling
Alexander Grimm
Original Assignee
Sennheiser Electronic Gmbh & Co. Kg
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sennheiser Electronic Gmbh & Co. Kg filed Critical Sennheiser Electronic Gmbh & Co. Kg
Priority to US13/514,533 priority Critical patent/US20120274220A1/en
Publication of WO2011070062A1 publication Critical patent/WO2011070062A1/fr
Publication of WO2011070062A4 publication Critical patent/WO2011070062A4/fr

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Classifications

    • 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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • 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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H05B45/12—Controlling the intensity of the light using optical feedback

Definitions

  • the present invention relates to a display LED unit and a method for controlling display LEDs.
  • LEDs Light emitting diodes LEDs have been known for many years and are used in many different products and devices. A possible use of these LEDs are display units, with an LED, for example, indicates whether a device is in standby mode or is turned on.
  • the perceptibility of such LEDs depends on their light intensity as well as the lighting conditions in the environment of the device. Usually, light sensors are used to determine the ambient light. Based on these measurements, the intensity of the LEDs can be adjusted accordingly.
  • US 7,508,317 B2 describes a method for controlling the light intensity of power LEDs in a railway signal lamp. The control is based on the photoelectric effect that is triggered by these power LEDs when light falls on the LEDs. For this purpose, the light-emitting diodes are operated in first time intervals in a first mode as LEDs and operated in second time intervals as photodiodes, ie the LEDs are operated in a second mode passive as photodiodes or as light sensors. During this time, no voltage is applied to the LEDs.
  • the intensity detected in the second mode is then used to control the brightness of the LEDs in the first mode. This is done based on a current or voltage control.
  • the time interval for the second mode is selected to be much smaller than the time interval for the first mode. It is an object of the present invention to provide a display LED unit and a method of controlling a display LED which can easily adjust the intensity of the LEDs to the ambient light level.
  • This object is achieved by a display LED unit according to claim 1 and by a method for controlling display LEDs according to claim 5.
  • a display LED unit is provided with at least one light emitting diode having a first and second mode.
  • the LED is operated in forward mode in a first mode and a light signal is output in response to the forward voltage applied to the LED.
  • the LED is operated in a reverse mode in a second mode with a reverse voltage and a voltage signal is output in response to the ambient light.
  • the display LED unit further includes a control unit for controlling the light emission of the LED in the first mode in response to the ambient light detected by the LED in the second mode.
  • the control unit is configured to control the LED by a pulse width modulated signal in first and second time intervals. In the first time intervals is the first mode and in the second time intervals, the second mode is activated.
  • control unit is configured to control the length of the first time intervals as a function of the light intensity of the ambient light detected in the second operating mode.
  • control unit is configured to detect the voltage on the LED in the second mode.
  • the invention also relates to a method for controlling a display LED.
  • An LED is operated in forward mode in a first mode.
  • the LED is operated in reverse mode in the second mode.
  • the voltage applied to the LED in the second mode is detected.
  • the LED is controlled in the first mode based on the voltage detected in the second mode on the LED.
  • the invention relates to the idea of using an LED both for generating light (first mode) and for detecting ambient light (second mode).
  • the LED is operated in a first operating mode (emitting light) in forward operation and in a second operating mode as a light sensor in reverse operation.
  • a voltage is applied to the LED in both the first and second modes.
  • the ambient light intensity detected in the second mode is used to control the LEDs in the first mode.
  • the intensity of the LEDs in the first mode can be controlled by a pulse width modulation PWM.
  • the fundamental frequency of the pulse width modulation can be> 100 Hz.
  • Fig. 1 shows a schematic circuit of an LED in a reverse operation according to a first embodiment
  • FIG. 2 is an illustration of a display LED unit according to a second embodiment.
  • FIG. 2 is an illustration of a display LED unit according to a second embodiment.
  • Fig. 1 shows a basic circuit of an LED in a reverse operation according to a first embodiment.
  • a light emitting diode LED 10 and a resistor 20 with 10M ohms is shown.
  • the LED 10 and the resistor 20 are connected in series between the voltages V C c and V S s.
  • Via the LED 10 a voltage U L ED drops.
  • This voltage U L ED drops at the LED 10 when it is operated in reverse operation as shown in Fig. 1.
  • This voltage U L ED changes due to a change in the internal resistance R, the LED 10 with changes in the ambient light.
  • the resistor 20 serves as a high-impedance resistor in order to be able to measure the voltage U L ED well.
  • an LED is operated in a display LED unit in a first mode (LED) and in a second mode (sensor operation).
  • the LED In the first mode, the LED is in forward mode with a corresponding forward voltage, and in the second mode, the LED is turned on in a reverse mode. operated with a corresponding reverse voltage.
  • the control of the display LED can be done by a control unit such as a microcontroller.
  • the display LED unit includes a control unit 100, a light emitting diode LED 10, first, second, and third resistors R1, R2, R3, and a capacitor C1.
  • the display LED unit has ports P2 - P5.
  • the LED 10 is provided in series with the second resistor R2 between a fourth and fifth terminals P4, P5. Between the LED 10 and the second resistor R2, a voltage U M is measured at a first node N1.
  • a first resistor R1 is provided between the node N1 and a third terminal P3.
  • the capacitor C1 is provided between ground and a second node N2.
  • the third resistor R3 is provided between the second node and the second terminal P2.
  • the control unit 100 optionally has an amplifier unit 110, which has a first and second connection CAO, CA1.
  • the first terminal CAO may be coupled to the second node N2, and the second terminal CA1 may be coupled to the first node N1 and thus receive the measurement voltage U M.
  • the terminals P3, P4, P5 represent input / output terminals.
  • the voltage U M can optionally be measured by a sigma-delta analog-to-digital converter.
  • This sigma-delta analog-to-digital converter is formed by the terminal P2 (with the series connection of the resistor R3 and the capacitor C1) and by the first and second terminals CAO, CA1 of the amplifier 110.
  • the display LED unit according to the second embodiment can be operated in a first mode (LED mode) and in a second mode (light sensor).
  • a first mode of operation a low level signal is applied to the third terminal P3 and the fourth terminal P4, respectively, while a high level signal is output to the fifth terminal.
  • the terminal P3 serves as a high-impedance input and the fourth terminal P4 is an output signal with a high level and at the fifth terminal P5 is an output signal with a low level on.
  • the LED 10 In the first mode (LED), the LED 10 is driven by a pulse width modulated PWM signal.
  • the fundamental frequency of this PWM signal should preferably be> 100 Hz. If the PWM signal is high, then light up tet the LED 10. The luminosity of the LED 10 is then determined by the pulse width.
  • the LED 10 In the second operating mode (sensor operation), the LED 10 is operated as a sensor. While the LED 10 is operated in the forward mode in the first mode, the LED 10 is operated in reverse mode in the second mode. When the PWM signal is at a low level, the LED 10 is switched as a light sensor and operated in reverse operation. According to the existing ambient light, a measuring voltage U M will be present at the node N1. This measurement voltage U M is measured by the sigma-delta analog-to-digital converter.
  • the resulting resistance of the LED 10 results from a parallel connection of the first and second resistors, i. H. a parallel connection of 400 ohms and 10M ohms, d. H. the resulting resistance is about 400 ohms.
  • the resolution of the analog-to-digital converter is low to provide sufficient speed of the analog-to-digital converter.
  • the process clock of the microcontroller should be high to provide fast conversion in the first mode.
  • the resistor R3 and the capacitor C1 can be selected according to the desired resolution. The resolution is chosen only low because the sigma-delta analog / digital converter requires a certain conversion time and you i. A. does not need many brightness levels. For other, faster voltage measurement methods, a higher resolution can also be selected. It depends on how many brightness levels you want to detect in the marked section.
  • the PWM signal has first and second time intervals.
  • the display LED unit During the first time intervals, the display LED unit becomes in the first mode, and in the second time intervals, the display LED unit operates in a second mode.
  • the second time interval should at least be designed so that a voltage measurement can take place.
  • control unit 100 microcontroller
  • the luminance of the LEDs in the first mode can be controlled based on the measured luminous intensity in the second mode.
  • LEDs with the exception of red and non-transparent LEDs.
  • the display LED unit according to the invention can be used in a mobile device or a mobile electronic device.
  • the mobile electronic device can have a battery in the housing.
  • By means of the display LED unit according to the invention it is possible to save energy or current (as a function of the detected brightness in the surroundings of the device) by controlling the light emission of the light-emitting diodes.
  • the mobile device may further include a display having a display LED unit. This display LED unit can be used to illuminate or backlight the display. Alternatively, in addition, the display LED unit may also be included as part of the display, i. used to represent the corresponding data.
  • the current measured in the LED according to the invention can be used to control the display, in particular to save power.
  • the display LED unit can also be used with other electronic devices.
  • the display LED unit is used to control the brightness of a display or the backlight or backlight of a keyboard. This can be done in particular with a view to improving the energy efficiency.
  • the display LED unit according to the invention can be dispensed with a separate diode for detecting the brightness of the environment.
  • the brightness detected by the display LED unit of the present invention can be used to control (a part / element) of a mobile electronic device.

Landscapes

  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Control Of El Displays (AREA)
  • Led Devices (AREA)

Abstract

L'invention concerne une unité d'affichage à diodes électroluminescentes (LED) comprenant au moins une diode électroluminescente (10) présentant un premier et un second mode de fonctionnement. Dans un premier mode de fonctionnement, la diode électroluminescente (LED) (10) est actionnée en mode de conduction directe et un signal lumineux est émis en fonction de la tension directe appliquée à la diode électroluminescente. Dans un second mode de fonctionnement, la diode électroluminescente (LED) (10) est actionnée en mode inverse avec une tension inverse et un signal de tension est émis en fonction de la lumière ambiante. L'unité d'affichage à diodes électroluminescentes (LED) présente en outre une unité de commande (100) servant à réguler l'émission de lumière de la diode électroluminescente (LED) (10) dans le premier mode de fonctionnement en fonction de la lumière ambiante détectée par la diode électroluminescente (LED) (10) dans le second mode de fonctionnement.
PCT/EP2010/069162 2009-12-08 2010-12-08 Unité d'affichage à diodes électroluminescentes (led) et procédé de commande de diodes électroluminescentes (led) pour affichage WO2011070062A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US13/514,533 US20120274220A1 (en) 2009-12-08 2010-12-08 Display led unit and method for controlling display leds

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102009057124A DE102009057124A1 (de) 2009-12-08 2009-12-08 Anzeigen-LED-Einheit und Verfahren zum Steuern von Anzeigen-LEDs
DE102009057124.8 2009-12-08

Publications (2)

Publication Number Publication Date
WO2011070062A1 true WO2011070062A1 (fr) 2011-06-16
WO2011070062A4 WO2011070062A4 (fr) 2011-08-18

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PCT/EP2010/069162 WO2011070062A1 (fr) 2009-12-08 2010-12-08 Unité d'affichage à diodes électroluminescentes (led) et procédé de commande de diodes électroluminescentes (led) pour affichage

Country Status (3)

Country Link
US (1) US20120274220A1 (fr)
DE (1) DE102009057124A1 (fr)
WO (1) WO2011070062A1 (fr)

Cited By (1)

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DE102013001273A1 (de) * 2013-01-25 2014-07-31 GM Global Technology Operations LLC (n. d. Gesetzen des Staates Delaware) Verfahren zur Regelung eines Scheinwerfers

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US11191141B1 (en) * 2020-12-17 2021-11-30 Lumileds Llc Powering microLEDs considering outlier pixels

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US7508317B2 (en) 2005-10-27 2009-03-24 Alcatel Control of the luminous intensity of power LEDs by using the photoelectric effect characteristics of said power LEDs
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Publication number Publication date
US20120274220A1 (en) 2012-11-01
WO2011070062A4 (fr) 2011-08-18
DE102009057124A1 (de) 2011-06-09

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