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Operation of organic light emitting diodes by means of pulse width modulation

A technology of pulse width modulation and light-emitting diodes, applied in the direction of electroluminescence light source, light source, electric light source, etc., can solve the problems affecting OLED capacitance, etc., and achieve the effect of improving accuracy and precise detection

Inactive Publication Date: 2012-11-21
特里多尼克股份有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, the roughly 100 nm thickness of the organic layer between the electrodes also affects the capacitance of the OLED

Method used

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  • Operation of organic light emitting diodes by means of pulse width modulation
  • Operation of organic light emitting diodes by means of pulse width modulation
  • Operation of organic light emitting diodes by means of pulse width modulation

Examples

Experimental program
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Embodiment Construction

[0063] Figure 5 A driver circuit 1 according to the invention is shown, which can implement the driver method according to the invention. In this case, the driver circuit 1 is connected to the OLED 2 . Here, the drive circuit 1 includes a drive unit 3 that supplies current to the OLED. The power supply to OLED 2 takes place by means of pulse width modulation (PWM). The drive unit 3 is controlled by a control unit 4 . The control unit 4 controls the drive unit 3 in such a way that it adjusts the PWM current pulses, in particular their amplitude and pulse width t P , and to adjust the PWM vacancy, especially its width t L . Furthermore, the control unit 4 is suitable, for example, as Figure 4 As shown, the falling edge at the end of the PWM current pulse of the OLED 2 is shortened using circuit technology, for example by short-circuiting. This avoids afterglow of OLED 2 in PWM vacancy. To this end, for example, a low-impedance jumper conductor is connected in parallel ...

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Abstract

The invention relates to the use of the effect that the high parasitic capacities of an organic light emitting diode (OLED) in pulse width modulation (PWM) mode can result in an extended drop in luminosity after every PWM current pulse. This can be advantageously used by means of a first method, which prevents the luminosity from dropping to 0 in the PWM gaps in order to prevent a so-called string of pearls effect when moving the OLED. In a second method, the afterglow of the OLED is counteracted without consideration of the string of pearls effect in order to achieve better color characteristics. Instead, the dropping flanks can be shortened or adjusted under control. In a third method, said effect is addressed upon activating the OLED in that the rising flanks are shortened at the start by an increase of operating current in order to achieve the target luminosity value more quickly. The methods are carried out by an operating circuit or control unit according to the invention.

Description

technical field [0001] The invention relates to a method and a circuit for driving organic light-emitting diodes by means of pulse width modulation. In particular, the present invention advantageously uses the parasitic capacitance of the OLED to drive the OLED. Background technique [0002] Organic light-emitting diode, referred to as OLED (abbreviation of "Organic Light-Emitting Diode" in English), is a thin-film-shaped, light-emitting component made of organic and semiconductor materials. The difference between it and an inorganic light-emitting diode (LED) is that, Current and optical densities are lower and single crystal materials are not required. Because OLEDs can be pressed onto almost any material, they offer significant cost savings over LCD technology. Flexible carrier materials (flexible substrates, films) can also be used for OLEDs, thus opening up completely new possibilities. [0003] A drive circuit is used to drive the OLED. In this case, the OLED is us...

Claims

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Application Information

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IPC IPC(8): H05B33/08H05B44/00
CPCY02B20/36H05B33/0896H05B45/60Y02B20/30
Inventor 爱德华多·佩雷拉迈克尔·齐默尔曼
Owner 特里多尼克股份有限公司
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