DE102018129945A1 - OPTOELECTRONIC DISPLAY DEVICE AND METHOD FOR OPERATING AN OPTOELECTRONIC DISPLAY DEVICE - Google Patents

Abstract

An optoelectronic display device (10) comprises a plurality of pixels (12), each pixel (12) at least one first optoelectronic semiconductor component (13) for generating light of a first color and a second optoelectronic semiconductor component (14) for generating light of a second Color, and a control unit (16) which is designed to apply a first pulse-width-modulated signal to the first optoelectronic semiconductor component (13) of at least one of the pixels (12) and the second optoelectronic semiconductor component (14) of the at least one pixel (12) to be loaded with a second pulse width modulated signal, the pulses (20) of at least one of the first and the second pulse width modulated signals each having a first pulse part (21) and a second pulse part (22) and the first pulse part (21) having a greater pulse height than that second pulse part (22), or wherein the pulses (31) of the first pulse width module rten signal and the pulses (32) of the second pulse width modulated signal have different pulse lengths.

Description

The present invention relates to an optoelectronic display device and a method for operating an optoelectronic display device.

In one type of conventional display device, the image is generated by a pixel-fine circuit of LEDs (light emitting diodes). In these display devices there is no imaging element such as an LCD (liquid crystal display) in front of a light source, but each pixel of the display device consists of several LED semiconductor chips, in particular three LED semiconductor chips, which light in the basic colors red, green and Emit blue. The LEDs are operated with pulse width modulation (PWM), also called pulse width modulation, pulse duration modulation or pulse length modulation.

The LEDs of the primary colors red, green and blue are manufactured with different technologies, which can lead to the fact that different parasitic capacitances of the different LED types lead to different switch-on delays and can generate image artifacts, in particular deviations from the white point, for short pulse lengths.

Display devices with LEDs are controlled today in line multiplex operation. For this purpose, all LED cathodes of a pixel column and color are usually connected to a common driver output, the so-called low side driver (English: low side driver). This output acts as a current sink, so that by switching on, i.e. H. the lowering of the cathode potential, a constant current can be set. The anodes of the LEDs in a row are combined row by row and are alternately connected to the supply voltage via a multiplexer. Inactive lines are usually kept in a "parking position" whose potential is low enough to suppress lighting.

Circuit concepts used today allow the specification of the LED current per color in order to hit the white point as precisely as possible for a given duty cycle. Working points for the LEDs of the primary colors, for example red, green and blue, thus result from the given target brightness of the display device, LED characteristics and duty cycle. Since different material systems are used for LEDs of different basic colors, these LEDs have very different junction capacities, even with the same size, which have to be charged each time they are switched on.

Since in line multiplex operation several identical LEDs are connected in parallel to a driver output, the effective parasitic capacitance increases by the multiplex factor, which is typically 32, for example in so-called fine pitch displays. As a consequence, in practice there is a different switch-on time for the light emission of the primary colors despite the identical switch-on time for the LED current. Red LEDs in particular light up earlier, which can lead to a shift in the color location to red in the case of very short pulse lengths, the so-called red shift.

The present invention has for its object inter alia to provide an advantageous optoelectronic display device which compensates for the different switch-on behavior of different optoelectronic semiconductor components. A corresponding method for operating an optoelectronic display device is also to be specified.

An object of the invention is achieved by an optoelectronic display device having the features of claim 1.

Furthermore, an object of the invention is achieved by a method for operating an optoelectronic display device having the features of claim 13. Advantageous embodiments and developments of the invention are specified in the dependent claims.

An optoelectronic display device comprises a plurality of pixels. The pixels form a display and can be arranged, for example, in a matrix of rows and columns. Each of the pixels comprises at least a first optoelectronic semiconductor component that is designed to generate light of a first color and a second optoelectronic semiconductor component that is configured to generate light of a second color. The first and second colors are different colors. In addition, each pixel can also contain one or more further optoelectronic semiconductor components and further components.

Furthermore, the optoelectronic display device comprises a control or driver unit which controls the first and the second optoelectronic semiconductor component at least one of the pixels. The control unit is designed to apply a first pulse width modulated signal to the first optoelectronic semiconductor component of one of the pixels and to apply a second pulse width modulated signal to the second optoelectronic semiconductor component. The control unit can also Drive optoelectronic semiconductor components of the other pixels with suitable signals, in particular pulse-width-modulated signals.

According to a first embodiment of the optoelectronic display device, the pulses of at least one of the first and the second pulse-width-modulated signals each have a first pulse part and a second pulse part, the first pulse part having a greater pulse height or amplitude than the second pulse part. The second pulse part can directly follow the first pulse part in time, i. that is, there is no pause between the first pulse part and the second pulse part. It can be provided that only one of the first and the second pulse width modulated signal has the two pulse parts described with the increased pulse height of the first pulse part, or that both the first and the second pulse width modulated signal each have the structure described, in which case the two pulse parts in the two signals, in particular the increased pulse height of the first pulse part, are configured differently.

The first pulse part brings about a targeted increase in the current flowing through the respective optoelectronic semiconductor component for a short time. As a result, the loading of the junction capacitance of the optoelectronic semiconductor component is accelerated, which has the result that it begins to emit light earlier in comparison to the application of a pulse which has the pulse height of the second pulse part over the entire pulse length or pulse duration. The second pulse part generates a current flow through the respective optoelectronic semiconductor component, which causes the optoelectronic semiconductor component to generate light with the desired brightness. The first pulse part and in particular its pulse height can be set in such a way that the first and the second optoelectronic semiconductor component light up essentially simultaneously and artifacts with regard to the color location are minimized.

The necessary pulse lengths and pulse heights for all colors implemented in the optoelectronic display device can be specified to the control unit via a configuration register with each initialization by the external control and applied to each pulse. In fact, there are not just two, but three operating states on each LED possible, ie the operating states off, on with charging current and on with operating current.

According to a second embodiment, the pulses of the first pulse width modulated signal and the pulses of the second pulse width modulated signal have different pulse lengths or pulse durations. The pulses of the first and the second pulse-width-modulated signal generally have only one pulse height. The pulse lengths of the first and second pulse-width-modulated signals can be modified in such a way that the switch-on delay is compensated for and the first and second optoelectronic semiconductor components light up essentially simultaneously or essentially of the same length. For the optoelectronic semiconductor component with the largest capacity, the pulse length is increased the most for this. The optoelectronic component with the smallest capacity is no longer energized.

The necessary pulse durations for the implemented colors can be specified to the control unit via a configuration register with each initialization by the external control and in particular added to each pulse.

The optoelectronic display device described here makes it possible to expand the usable dynamic range for dimming via pulse width modulation. Without the specified concept, the dynamic range is limited by the fact that if the current pulses or switching times are too short, the color-specific switch-on delay leads to the white point or color location generally running away, since the spectral contributions of the primary colors deviate from the target value.

Due to the compensation of the switch-on time, the permissible value range for the parasitic capacitance is significantly expanded when selecting the optoelectronic semiconductor components for the optoelectronic display device.

Epitaxial structures that require a higher junction capacitance per area to increase quantum efficiency can also be used. This can increase system efficiency.

It can be provided that either the first embodiment or the second embodiment is implemented in the optoelectronic display device. Both configurations can also be implemented, one of the two configurations being selected during the operation of the optoelectronic display device. Furthermore, it is at least conceivable to combine the first and the second configuration with one another. In this case, the pulses of the first and second pulse width modulated signals have different pulse lengths and, in addition, the pulses of at least one of the two pulse width modulated signals have two pulse parts as described above.

The optoelectronic semiconductor components can, for example, as light-emitting diodes (English: light emitting diodes, LEDs), as organic light-emitting diodes (English: organic light-emitting diodes, OLEDs), as light-emitting transistors or as organic light-emitting transistors. In various embodiments, the optoelectronic semiconductor components can be parts of integrated circuits.

The optoelectronic semiconductor components can in particular be implemented as optoelectronic semiconductor chips.

In addition to the optoelectronic semiconductor components and the control unit, the optoelectronic display device can also contain further semiconductor components and / or components.

The optoelectronic display device can be used, for example, in video walls, RGB displays or display boards. Furthermore, the optoelectronic display device can be used in vehicle applications. For example, the optoelectronic display device can be integrated in displays, in particular in the dashboard, of vehicles.

According to one embodiment, the pulse height of the first pulse part is increased compared to the pulse height of the second pulse part in such a way that the first optoelectronic semiconductor component and the second optoelectronic semiconductor component simultaneously start to generate light in response to a pulse of the first and the second pulse width modulated signal, or that that generate the first optoelectronic semiconductor component and the second optoelectronic semiconductor component in response to a pulse of the first and the second pulse width modulated signal of the same length.

According to a further embodiment, the pulse lengths of the pulses of the first pulse-width-modulated signal and the second pulse-width-modulated signal are designed such that the first optoelectronic semiconductor component and the second optoelectronic semiconductor component simultaneously begin to generate light in response to a pulse of the first and the second pulse-width-modulated signal or that the first optoelectronic semiconductor component and the second optoelectronic semiconductor component generate light of the same length in response to a pulse of the first and the second pulse width modulated signal.

In addition to the first and the second optoelectronic semiconductor component, each of the pixels can comprise a third optoelectronic semiconductor component that is designed to generate light of a third color. The third color differs from the first and the second color. The basic colors red, green and blue can be generated with three optoelectronic semiconductor components per pixel. Furthermore, the control unit is designed to apply a third pulse-width-modulated signal to the third optoelectronic semiconductor component of the at least one pixel.

In the event that the first embodiment described above is used, the pulses of at least two of the first, the second and the third pulse-width-modulated signal, with which the three optoelectronic semiconductor components of the same pixel are applied, can each have a first pulse part and a second pulse part , wherein the first pulse part has a greater pulse height than the second pulse part.

When the second embodiment described above is used, the pulses of the first pulse-width modulated signal, the pulses of the second pulse-width modulated signal and the pulses of the third pulse-width modulated signal have different pulse lengths.

The optoelectronic display device can comprise at least one first current source and at least one second current source. The first current source is designed to generate the first pulse part and the second current source is designed to generate the second pulse part. The first and the second current source can alternately be connected to the corresponding optoelectronic semiconductor component in order to apply this first and second pulse part to this optoelectronic semiconductor component.

In order to achieve a substantially simultaneous or equally long illumination of the first and the second optoelectronic semiconductor component, the pulse height of the first pulse part can be increased by a factor in the range from 1.5 to 10 compared to the pulse height of the second pulse part. Furthermore, this factor can be in the range from 1.5 to 5 and in particular in the range from 1.5 to 3.

If, according to the second embodiment, the pulse lengths of the pulses of the first pulse width modulated signal and the second pulse width modulated signal are selected differently, the pulse lengths of the pulses of the first pulse width modulated signal and the second pulse width modulated signal can vary by a length or duration in the range from 20 ns to Distinguish 1 µs in order to cause the first and second optoelectronic semiconductor components to light up substantially simultaneously or for the same length. Furthermore, the time difference can be in the range from 50 ns to 500 ns and in particular in the range from 50 ns to 300 ns.

The optoelectronic display device can have an analysis unit which is designed to deliver the characterization data necessary for the compensation of the different switch-on behavior of the optoelectronic semiconductor components. In particular, the analysis unit can determine the junction capacitance of the optoelectronic semiconductor components that emit light of different colors, or the junction capacitance differences thereof.

To determine the characterization data, the analysis unit can record measured values on a fourth optoelectronic semiconductor component, on a fifth optoelectronic semiconductor component and in particular on a sixth optoelectronic semiconductor component, the fourth, fifth and sixth optoelectronic semiconductor component for generating light of the first, second and third color, for example red, green or blue.

The analysis unit can use the measured values to determine the increase in the pulse height of the first pulse part compared to the pulse height of the second pulse part or the pulse length difference between the pulses of the first pulse-width-modulated signal and the second pulse-width-modulated signal and optionally the third pulse-width-modulated signal.

For example, the values for the optimal pulse height increase or the optimal pulse length difference can be stored in a look-up table against the measured variable measured by the analysis unit in order to enable the analysis unit to determine those values for the pulse height increase or the pulse length difference for the determined measured values. which optimally compensates for the different switch-on behavior.

The fourth, fifth and in particular sixth optoelectronic semiconductor components can be arranged outside the pixels of the display, i. that is, the optoelectronic semiconductor components used for measurement purposes do not belong to the image content-reproducing optoelectronic semiconductor components in this embodiment, but only serve to determine the characterization data. For example, these optoelectronic semiconductor components can be arranged on the back of the optoelectronic display device.

Alternatively, one of the pixels of the display can comprise the fourth, fifth and in particular sixth optoelectronic semiconductor component. In this case, these optoelectronic semiconductor components are used not only to determine the characterization data, but also to reproduce the image content. It can further be provided that the fourth, fifth and sixth optoelectronic semiconductor component is identical to the first, second and third optoelectronic semiconductor component.

The analysis unit can be designed such that it applies a modulated signal to each of the fourth, fifth and in particular the sixth optoelectronic semiconductor component and measures the phase shift between the modulated signal and the response signals from the fourth, fifth and in particular the sixth optoelectronic semiconductor component. The respective phase shifts represent the measured values from which the values for the pulse height increase or the pulse length difference can be generated.

Furthermore, the analysis unit can be designed such that it applies a signal jump or a signal pulse to the fourth, the fifth and in particular the sixth optoelectronic semiconductor component and the response signal of the fourth, fifth and in particular the sixth optoelectronic semiconductor component to the signal jump or the signal pulse measures. The respective response signals represent the measured values from which the values for the pulse height increase or the pulse length difference can be generated.

A method according to one embodiment serves to operate an optoelectronic display device. The optoelectronic display device comprises a plurality of pixels, each pixel comprising at least a first optoelectronic semiconductor component for generating light of a first color and a second optoelectronic semiconductor component for generating light of a second color. The first optoelectronic semiconductor component of at least one of the pixels is subjected to a first pulse width modulated signal and the second optoelectronic semiconductor component of the at least one pixel is applied to a second pulse width modulated signal. According to a first embodiment, the pulses of at least one of the first and the second pulse-width-modulated signals each have a first pulse part and a second pulse part, and the first pulse part has a greater pulse height than the second pulse part. According to a second embodiment, the pulses of the first pulse width modulated signal and the pulses of the second pulse width modulated signal have different pulse lengths.

The method of operating an optoelectronic display device can be the above have described embodiments of the optoelectronic display device.

• 1 einen schematischen Schaltplan einer optoelektronischen Anzeigevorrichtung;
• 2 eine Darstellung eines PWM-Signals;
• 3 eine Darstellung eines durch eine LED fließenden Strompulses und der von der LED erzeugten Lichtemission;
• 4 eine Darstellung eines durch eine LED fließenden Strompulses mit zwei unterschiedlichen Pulshöhen und der von der LED erzeugten Lichtemission;
• 5 eine Darstellung von durch drei LEDs fließenden identischen Strompulsen;
• 6 eine Darstellung von durch drei LEDs fließenden Strompulsen mit unterschiedlichen Pulslängen;
• 7 einen schematischen Schaltplan einer optoelektronischen Anzeigevorrichtung mit einer Analyseeinheit sowie externen Referenz-LEDs;
• 8 einen schematischen Schaltplan einer weiteren optoelektronischen Anzeigevorrichtung mit einer Analyseeinheit sowie internen Referenz-LEDs;
• 9 eine Ausgestaltung der Analyseeinheit für die optoelektronische Anzeigevorrichtung gemäß 7; und
• 10 eine Ausgestaltung der Analyseeinheit für die optoelektronische Anzeigevorrichtung gemäß 8.

Exemplary embodiments of the invention are explained in more detail below with reference to the attached drawings. These show schematically:

• 1 a schematic circuit diagram of an optoelectronic display device;
• 2nd a representation of a PWM signal;
• 3rd a representation of one by one LED flowing current pulse and that of the LED generated light emission;
• 4th a representation of one by one LED flowing current pulse with two different pulse heights and that of the LED generated light emission;
• 5 a representation of identical current pulses flowing through three LEDs;
• 6 a representation of current pulses flowing through three LEDs with different pulse lengths;
• 7 a schematic circuit diagram of an optoelectronic display device with an analysis unit and external reference LEDs;
• 8th a schematic circuit diagram of a further optoelectronic display device with an analysis unit and internal reference LEDs;
• 9 an embodiment of the analysis unit for the optoelectronic display device according to 7 ; and
• 10th an embodiment of the analysis unit for the optoelectronic display device according to 8th .

In the following detailed description, reference is made to the accompanying drawings, which form a part of this specification and in which, by way of illustration, specific embodiments are shown in which the invention may be practiced. Since components of exemplary embodiments can be positioned in a number of different orientations, the directional terminology serves for illustration and is in no way restrictive. It goes without saying that other exemplary embodiments can be used and structural or logical changes can be made without departing from the scope of protection. It is understood that the features of the various exemplary embodiments described herein can be combined with one another, unless specifically stated otherwise. The following detailed description is, therefore, not to be taken in a limiting sense. Identical or similar elements are provided with identical reference symbols in the figures, insofar as this is expedient.

1 shows a schematic circuit diagram of an optoelectronic display device 10th . The optoelectronic display device 10th contains a display 11 with a variety of pixels 12 , which are arranged in a matrix of rows and columns and in the present exemplary embodiment three each as LED executed optoelectronic semiconductor components contain. One of the pixels with LEDs 13 , 14 and 15 is illustrative in 1 shown enlarged. The LED 13 generates light of the color red, the LED 14 produces light of the color green and the LED 15 produces light of the color blue.

The optoelectronic display device furthermore contains 10th a control unit 16 or a driver that the LEDs 13 , 14 , 15 all pixels 12 of the display 11 each with a suitable control signal 17th acted upon. During the operation of the optoelectronic display device 10th to display visual content on the display 11 are the control signals 17th pulse width modulated signals.

A control signal plotted against time t is an example 17th , ie a pulse width modulated signal with which one of the LEDs 13 , 14 , 15 is acted upon in 2nd shown. The control signal 17th can have two discrete values, ie a first value 18th and a second value 19th accept. In the period in which the control signal 17th the first value 18th assumes a rectangular pulse with a pulse width t _pulse generated. The pulse is periodic with a period length T repeated. If the control signal 17th the first value 18th assumes, ie during the duration t _pulse of the pulse, a current flows I _LED through the LED , which causes the LED Light emitted in the respective color. By the amount of current I _LED is the brightness of that of the LED emitted light determined. During the rest of the time, no current flows through the LED .

In 3rd is for one LED the current flowing during a pulse I _LED shown. Furthermore, this is from the LED emitted light against time t is shown. The current pulse I _LED begins at time t ₁ and ends at time t ₂ . The LED however, does not light up immediately at time t ₁ , but only begins to light up with a switch-on delay Δt ₁ .

The switch-on delay can be shortened by applying a prepulse with a larger pulse height before the pulse begins. This is exemplified in 4th shown in which the by the LED flowing current I _LED as well as that of LED emitted light are plotted against time t. A pulse 20th of the pulse width modulated signal consists of a first part of the pulse 21st and one directly on the first part of the pulse 21st following second pulse part 22 , the first part of the pulse 21st a larger pulse height than the second pulse part 22 and therefore during the first part of the pulse 21st a bigger stream I _LED through the LED flows as during the second pulse part 22 . The first part of the pulse 21st and the second part of the pulse 22 can by appropriate power sources in the control unit 16 be generated. Because of the initial increased current flow through the LED the switch-on delay Δt _{2 is} shortened compared to the switch-on delay Δt ₁ , as shown in the upper illustration in 4th can be removed.

According to a first embodiment, the control unit controls 16 at least the LEDs 14 and 15 of a pixel 12 with a respective pulse width modulated signal, the pulses of a first pulse part 21st and a second pulse part 22 have, the first pulse part 21st a larger pulse height than the second pulse part 22 having. The one through the LED 14 respectively. 15 during the second part of the pulse 22 flowing current I _LED can be dimensioned such that the LED 14 respectively. 15 emitted light has the desired brightness.

The LEDs 14 and 15 that produce green or blue light, in comparison to the red light emitting LED 13 a larger switch-on delay. Through the first pulse parts 21st With the increased pulse heights, the switch-on delays of the LEDs 14 and 15 reduced. If necessary, the LED 13 the same pixel 12 with one of first and second pulse parts 21st , 22 composite signal are applied.

The parameters of the first pulse parts 21st , ie in particular the pulse heights and the lengths or durations of the first pulse parts 21st , can for the LEDs 14 and 15 and if necessary also for the LED 13 so that the LEDs 13 , 14 , 15 essentially light up simultaneously or for the same length of time.

The pulse height of the first pulse part 21st can compared to the pulse height of the second pulse part 22 be increased by a factor in the range of 1.5 to 10. Furthermore, this factor can be in the range from 1.5 to 5 and in particular in the range from 1.5 to 3.

In 5 current pulses are shown as they are conventionally applied to the LEDs 13 , 14 , 15 be created. All current pulses have the same pulse length. As explained above, the LEDs start 13 , 14 , 15 due to different parasitic capacitances at different times with the light emission.

According to a second embodiment, the control unit controls 16 the green or blue light emitting LEDs 14 and 15 of a pixel 12 with pulse-width-modulated signals whose pulse lengths are increased, but whose pulse heights are constant over the entire pulse. As in 6 is shown has a current pulse 31 the red light emitting LED 13 the same pulse length as in 3rd on while a pulse 32 with which the LED 14 is applied by the time period Δt _{14 is} extended, and a pulse 33 with which the LED 15 is applied, is extended by the time period Δt ₁₅ , the time period Δt _{15 being} greater than the time period Δt ₁₄ .

The time periods Δt ₁₄ and Δt ₁₅ for lengthening the pulses 32 , 33 of the LEDs 14 and 15 can be selected in such a way that even with short pulse lengths the LEDs 13 , 14 , 15 light up essentially the same length.

The time periods Δt ₁₄ and Δt ₁₅ can be in the range from 20 ns to 1 μs and in particular in the range from 50 ns to 500 ns or in the range from 50 ns to 300 ns.

In 6 the pulses begin 31 , 32 , 33 at the same time. Alternatively, it can be provided that the pulses 31 , 32 , 33 end at the same time.

7 shows a schematic circuit diagram of an optoelectronic display device 40 who have a continuing education in 1 illustrated optoelectronic display device 10th represents. Next to the display 11 and the control unit 16 includes the optoelectronic display device 40 an analysis unit 50 as well as LEDs 51 , 52 and 53 . The LEDs 51 , 52 , 53 are not intended to display visual content, but only serve as reference or test LEDs. The LEDs 51 , 52 , 53 can be on the same panel as the LEDs 13 , 14 , 15 the pixel 11 be arranged, but in an area not visible to a viewer, such as on the back of the panel.

The LED 51 generates light of the color red, the LED 52 produces light of the color green and the LED 53 produces light of the color blue. In particular, the LEDs 51 , 52 , 53 identical in construction to one of the LEDs 11 , 12 , 13 who have emitted light of the same color.

The analysis unit 50 is with the LEDs 51 , 52 , 53 connected and takes measurements at the LEDs 51 , 52 , 53 to determine, for example, the respective junction capacity for the LEDs of the colors red, green and blue. The from the analysis unit 50 Measured values determined can be entered into a look-up table in which compensation parameters have been stored beforehand in order to be able to compensate for the different switch-on behavior of the LEDs of different colors. For example, the magnification of the Pulse height of the first pulse part compared to the pulse height of the second pulse part or the pulse length differences between the pulses of the different pulse width modulated signals.

The analysis unit 50 can take measurements on the LEDs 51 , 52 , 53 for example every time the display starts 11 as an initialization procedure or when calibrating the display 11 carry out.

Furthermore, the analysis unit 50 measured values at an output 55 be read out.

8th shows a schematic circuit diagram of an optoelectronic display device 60 which in large parts of the 7 illustrated optoelectronic display device 40 equal. In contrast to the optoelectronic display device 40 uses the optoelectronic display device 60 however no external reference LEDs, but selected LEDs 13 , 14 , 15 of the display 11 used to determine the characterization data necessary for the compensation of the different LED switch-on behavior.

The control unit 16 has a multiplexer 61 with which during the operation of the display 11 individual lines of the pixel matrix can be controlled. An analysis unit 62 is with the multiplexer 61 connected and can thus during an initialization procedure or a calibration of the display 11 the necessary measured values from selected LEDs 13 , 14 , 15 of the display.

The from the analysis unit 62 Measured values determined, in particular the determined values for the junction capacitance of the different LEDs, and / or the increase in the pulse height of the first pulse part compared to the pulse height of the second pulse part or the pulse length differences between the pulses determined from the look-up table can, for example, in the control unit 16 be filed. Alternatively, these values can also be loaded into the image preprocessing processor via the bus and taken into account in the color correction there.

9 shows an exemplary embodiment of the analysis unit 50 that in the in 7 illustrated optoelectronic display device 40 can be used.

The analysis unit 50 has a multiplexer 70 and a power source 71 . The power source 71 can be realized by one or more field-effect transistors (FET) and can generate a modulated or oscillating current signal with which the multiplexer can be used 70 the LEDs 51 , 52 , 53 be applied one after the other. The modulated current signal can, for example, have a frequency of 20 MHz and optionally a bias, that is to say a constant voltage is applied to the respective one LED placed. Alternatively, the LEDs 51 , 52 , 53 can also be supplied with a modulated voltage signal. Furthermore, the LEDs 51 , 52 , 53 not like in 9 shown with their cathodes but with their anodes with the multiplexer 70 be connected.

The analysis unit 50 can be designed such that they each LED 51 , 52 respectively. 53 with that from the power source 71 generated current signal is applied and the phase shift between the current signal and that above the respective LED 51 , 52 respectively. 53 falling voltage.

From the analysis unit 50 recorded measurement signals can, for example, the junction capacitance Cj0 of the respective LED without bias, ie uncharged, or the junction capacitance CjX can be derived with a bias X. Furthermore, the respective capacity can be extended to all M LEDs of the same color of a display line are extrapolated.

Alternatively, the analysis unit 50 be designed such that a respective LED 51 , 52 respectively. 53 is subjected to a signal jump, in particular a suddenly rising current, and then the voltage across the respective LED 51 , 52 respectively. 53 and thus their charging curve is measured.

The analysis unit can also use these measurements 50 the junction capacitance Cj0 of the respective LED without bias or derive the junction capacitance CjX with a bias X. Furthermore, the respective capacity can be extended to all M LEDs of the same color of a display line are extrapolated.

10th shows an exemplary embodiment of the analysis unit 62 that in the in 8th illustrated optoelectronic display device 60 can be used.

The analysis unit 62 like the analysis unit 50 via a power source 71 .

Within a column, a LED 13 , 14 or 15 with that from the power source 71 generated current signal are applied while the rest N LEDs in the column are switched off or “float”.

The analysis unit 62 can be designed such that the selected LED 13 , 14 or 15 is subjected to a signal jump, in particular a suddenly rising current, and then the voltage across the selected one LED 13 , 14 or 15 and thus their charging curve is measured.

Alternatively, the selected one LED 13 , 14 or 15 with one from the power source 71 generated modulated current signal (with or without bias) and the phase shift between the current signal and that over the selected LED 13 , 14 or 15 falling voltage can be measured.

The analysis unit can use these measurements 62 the junction capacitance cj0 of the respective LED 13 , 14 respectively. 15 without bias or derive the junction capacitance CjX with a bias X. Furthermore, the respective capacity can be extended to all M LEDs of the same color of a display line are extrapolated.

Reference symbol list

10th

optoelectronic display device

11

Display

12

pixel

13

LED

14

LED

15

LED

16

Control unit

17th

Control signal

18th

first value

19th

second value

20th

Pulse

21st

first part of the pulse

22

second part of the pulse

31

Pulse

32

Pulse

33

Pulse

40

optoelectronic display device

50

Analysis unit

51

LED

52

LED

53

LED

55

exit

61

multiplexer

62

Analysis unit

70

multiplexer

71

Power source

Claims (15)

Optoelectronic display device (10, 40, 60), with: a plurality of pixels (12), each pixel (12) comprising at least a first optoelectronic semiconductor component (13) for generating light of a first color and a second optoelectronic semiconductor component (14) for generating light of a second color, and a control unit (16) which is designed to apply at least one of the pixels (12) to the first optoelectronic semiconductor component (13) with a first pulse width modulated signal and to apply a second pulse width modulated signal to the second optoelectronic semiconductor component (14) of the at least one pixel (12) Signal to act upon wherein the pulses (20) of at least one of the first and the second pulse width modulated signals each have a first pulse part (21) and a second pulse part (22) and the first pulse part (21) has a greater pulse height than the second pulse part (22), or wherein the pulses (31) of the first pulse width modulated signal and the pulses (32) of the second pulse width modulated signal have different pulse lengths. Optoelectronic display device (10, 40, 60) according to Claim 1 , wherein the pulse height of the first pulse part (21) is increased compared to the pulse height of the second pulse part (22) such that the first optoelectronic semiconductor component (13) and the second optoelectronic semiconductor component (14) modulate in response to a pulse of the first and the second pulse width Signal start generating light simultaneously. Optoelectronic display device (10, 40, 60) according to Claim 1 or 2nd The pulse lengths of the pulses (31, 32) of the first pulse width modulated signal and the second pulse width modulated signal are designed such that the first optoelectronic semiconductor component (13) and the second optoelectronic semiconductor component (14) in response to a pulse (31, 32) of the first and the second pulse-width-modulated signal start generating light simultaneously. Optoelectronic display device (10, 40, 60) according to one of the preceding claims, wherein each pixel (12) comprises a third optoelectronic semiconductor component (15) for generating light of a third color, wherein the control unit (16) is designed to form the third optoelectronic semiconductor component (15) of the at least one pixel (12) with a third pulse width modulated signal, the pulses (20) of at least two of the first, the second and the third pulse width modulated signal each having a first pulse part (21) and have a second pulse part (22) and the first pulse part (21) has a greater pulse height than the second pulse part (22), or wherein the pulses (31) of the first pulse width modulated signal, the pulses (32) of the second pulse width modulated signal and the pulses (33) of the third pulse width modulated signal have different pulse lengths. Optoelectronic display device (10, 40, 60) according to one of the preceding claims, wherein the optoelectronic display device (10, 40, 60) comprises a first current source for generating the first pulse part (21) and a second current source for generating the second pulse part (22) . Optoelectronic display device (10, 40, 60) according to one of the preceding claims, wherein the pulse height of the first pulse part (21) is increased by a factor in the range from 1.5 to 10 compared to the pulse height of the second pulse part (22). Optoelectronic display device (10, 40, 60) according to one of the preceding claims, wherein the pulse lengths of the pulses (31, 32) of the first pulse width modulated signal and the second pulse width modulated signal differ by a length in the range from 20 ns to 1 µs. Optoelectronic display device (40, 60) according to one of the preceding claims, wherein the optoelectronic display device (40, 60) comprises an analysis unit (50, 62), the measurement values on a fourth optoelectronic semiconductor component (13, 51) for generating light of the first color and on a fifth optoelectronic semiconductor component (14, 52) for generation of light of the second color, and wherein the analysis unit (50, 62) uses the measured values to increase the pulse height of the first pulse part (21) compared to the pulse height of the second pulse part (22) or the pulse length difference between the pulses (31, 32) of the first pulse width modulated signal and the second pulse width modulated signal certainly. Optoelectronic display device (40) according to Claim 8 , wherein the fourth optoelectronic semiconductor component (51) and the fifth optoelectronic semiconductor component (52) are arranged outside the pixels (12). Optoelectronic display device (60) according to Claim 8 , wherein one of the pixels (12) comprises the fourth optoelectronic semiconductor component (13) and the fifth optoelectronic semiconductor component (14). Optoelectronic display device (40, 50) according to one of the Claims 8 to 10th , wherein the analysis unit (50, 62) is designed such that it records the measured values by applying a modulated signal to the fourth optoelectronic semiconductor component (13, 51) and the fifth optoelectronic semiconductor component (14, 52) and the phase shift between the modulated signal and the response signal of the fourth optoelectronic semiconductor component (13, 51) and the fifth optoelectronic semiconductor component (14, 52). Optoelectronic display device (40, 60) according to one of the Claims 8 to 10th , wherein the analysis unit (50, 62) is designed such that it records the measured values by applying a signal jump to the fourth optoelectronic semiconductor component (13, 51) and the fifth optoelectronic semiconductor component (14, 52) and the response signal of the fourth optoelectronic Semiconductor component (13, 51) and the fifth optoelectronic semiconductor component (14, 52) measures. Method for operating an optoelectronic display device (10, 40, 60), wherein the optoelectronic display device (10, 40, 60) comprises a plurality of pixels (12) and each pixel (12) has at least one first optoelectronic semiconductor component (1 3) for generating light of a first color and a second optoelectronic semiconductor component (14) Generating light of a second color includes wherein the first optoelectronic semiconductor component (13) is subjected to at least one of the pixels (12) with a first pulse width modulated signal and the second optoelectronic semiconductor component (14) of the at least one pixel (12) is subjected to a second pulse width modulated signal, and wherein the pulses (20) of at least one of the first and the second pulse width modulated signals each have a first pulse part (21) and a second pulse part (22) and the first pulse part (21) has a greater pulse height than the second pulse part (22), or wherein the pulses (31) of the first pulse width modulated signal and the pulses (32) of the second pulse width modulated signal have different pulse lengths. Procedure according to Claim 13 , wherein the pulse height of the first pulse part (21) is increased by a factor in the range from 1.5 to 10 compared to the pulse height of the second pulse part (22) or wherein the pulse lengths of the pulses (31, 32) of the first pulse width modulated signal and the second pulse width modulated signal differ by a length in the range of 20 ns to 1 µs. Procedure according to Claim 13 or 14 , Measured values on a fourth optoelectronic semiconductor component (13, 51) for generating light of the first color and on a fifth Optoelectronic semiconductor component (14, 52) for generating light of the second color are recorded, and the measured values are used to increase the pulse height of the first pulse part (21) compared to the pulse height of the second pulse part (22) or the pulse length difference between the pulses (31, 32) of the first pulse width modulated signal and the second pulse width modulated signal.

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