WO2018015537A1

WO2018015537A1 - Method for activating a light-emitting component when reading a cmos camera sensor and activating unit

Info

Publication number: WO2018015537A1
Application number: PCT/EP2017/068480
Authority: WO
Inventors: Désirée QUEREN; Dominik SCHULTEN
Original assignee: Osram Opto Semiconductors Gmbh
Priority date: 2016-07-21
Filing date: 2017-07-21
Publication date: 2018-01-25
Also published as: DE102016113443A1

Abstract

The present invention relates to a method for activating a light-emitting component when reading a CMOS camera sensor and to an activating unit. The invention provides an efficient technical concept that provides improved reading of a CMOS camera sensor illuminated by a light-emitting component, in that the light-emitting component (100) is operated in PWM mode with a pulse-width-modulated activation signal. The pulse-width-modulated activation of the light-emitting component advantageously also makes it possible to avoid a chromaticity point shift of the image of the camera sensor. The imaging quality of images sensed by means of the camera sensor is in this way advantageously increased.

Description

METHOD FOR CONTROLLING A LIGHT-EMITTING COMPONENT WHILE READING A CMOS CAMERA SENSOR AND CONTROL UNIT

DESCRIPTION

The present invention relates to a method for driving ^¬ ern a light-emitting device when reading a CMOS camera sensor and a drive device for a light-emitting device in combination with a CMOS camera sensor.

This patent application claims the priority of German patent application DE 10 2016 113 443.0, which is dependent Offenbarungsge ^¬ hereby incorporated by reference.

Light emitting devices in the form of LEDs are used in ^combination with a CMOS camera sensor as a detector. The LEDs can either be operated with a fixed electric current in continuous operation or with a fixed electric current over a longer pulse. The current level can be changed ver ^¬ it both in continuous operation and the pulse operation to achieve a brightness dimming. Alternatively, light-emitting components are operated in numerous applications in so-called PWM mode (English, pulse width modulation) with pulse-width-modulated drive signals.

For CMOS camera sensors that use the rolling shutter readout principle, the captured scenes or images are scanned or read in rows or columns.

Due to the line-wise or column-wise readout of the CMOS camera sensor operating according to the rolling shutter readout principle ("CMOS rolling shutter camera sensor"), however, in the case of a light modulated by the LEDs according to the PWM mode, different brightnesses can be achieved. Depending on the phase of the modulated illumination by the light-emitting component, either a completely bright line or an a completely dark line or a mixture of both. The resulting detected or read from ^¬ image can therefore have variations in brightness within the image and can thus appear blurry and out of focus on the viewer. In addition, there may be strong over- and underexposure effects on the CMOS camera sensor, which a CMOS driver can hardly compensate.

There are also CMOS camera sensors that work according to the rolling shutter readout principle according to the Global Shutter-Ausleseprinzip ("CMOS Global Shutter Camera Sensors"), in which all pixels of the CMOS camera sensor are read out simultaneously.

In the case of both said read-out principles (rolling shutter and global shutter), however, when using a light-emitting component in the form of LEDs in combination with a CMOS camera sensor as the detector, the further problem is that a brightness correction caused by the current change of the light-emitting component will simultaneously cause ^¬ on the basis of the current-dependent characteristics of the LEDs and in particular a change in the converter Far ^¬ Bortes.

What is important is the predictability of the color locus, in particular when using matrix LEDs with a plurality of light-emitting pixels. Here, many individual LED chips are controlled separately vonei ^¬ nander to selectively illuminate scenes and record with the CMOS camera sensor. A current dimming of the light-emitting component can lead to color inhomogeneities between the individual pixels in the detection with the CMOS camera sensor and thus to color inhomogeneities of the entire image, which are difficult to compensate with known processing algorithms.

The object on which the invention is based is to provide an improved method for driving a light-emitting component during operation of a camera. to provide rasensors and a drive device for a lichtemittie ^¬ ing component in combination with a CMOS camera sensor.

This object is achieved with the objects of the independent claims. Advantageous developments of the invention are the subject of dependent claims.

According to a first aspect, the invention provides a method for driving a light-emitting component in a readout of a CMOS camera sensor, comprising the step of: operating the light-emitting component in a PWM mode with a pulse-width-modulated drive signal.

According to a second aspect, the invention provides a Ansteu ^¬ ereinrichtung for a light emitting device in combination ^¬ nation with a CMOS-camera sensor, wherein the driving means is formed, operated in a PWM mode with a pulse ^¬ width modulated drive signal at a reading out of the CMOS camera sensor to become.

The light emitting device according to the invention in the so-called PWM mode ^¬ (English, pulse width modulation) operated with a pulse width modulated drive signal. The frequency of the pulse-width-modulated drive signals is such that a resulting operating ^{behavior of} the light-emitting components for a human observer can not be distinguished from a performance of a light-emitting component controlled by a constant drive signal.

Due to the PWM modulation, an increase in temperature of the light-emitting components due to power loss is advantageously reduced significantly. Thus, in egg ^¬ nem composite of several light-emitting components no sorting with respect to a temperature dependency and a luminous intensity of the individual light emitting devices are to be made. In addition, the brightness of the LED light-emitting device configured as for the viewer by different frequencies and different duty cycles with an unchanged color point va can be ^¬ riiert by said PWM modulation. When the brightness is adjusted via the electrical operating current, the color locus changes due to a current dependence of the LED chip or the converter mate ^¬ rials. This per se known color locus shift as a function of the electrical operating current can be avoided by said PWM modulation, since the current value can be kept constant here.

Advantageously, with the proposed method and with the proposed drive device, a brightness of the light-emitting component can be controlled by PWM modulation, whereby a color locus shift, which is conventionally generated by driving the light-emitting component by means of current dimming, can be avoided. Particularly advantageous method of the invention may arranged for example in a mobile phone with a on the back side, are used ^¬ light emitting device used as a flash in mobile terminals. An advantageous development provides that, in a CMOS camera sensor operating according to the rolling shutter readout principle, a frequency of the pulse-width-modulated drive signal of the light-emitting component is at least equal to or greater than a frequency of a line-wise or column-modulated readout signal of the CMOS camera sensor.

Camera sensor is. In this way, a sufficient Hel ^¬ ligkeit the image of the CMOS camera sensor can be realized.

A further advantageous embodiment of the method provides that the frequency of the drive signal of the lichtemittie ^¬ generating device is greater than the sixteen times the frequency ei ^¬ nes line or column-modulated readout signal of the CMOS camera sensor. In this way already one can usable homogeneity of a brightness distribution of the image of the camera sensor can be achieved without a Synchroni ^¬ sation is required. This method is supported by the fact that, in the presence of a converter, additional smoothing of intensity fluctuations of the pulsed light radiation is achieved.

A further advantageous development of the method provides that the frequency of the drive signal of the light-emitting component is greater than twenty times the frequency of a line-wise or column-wise modulated readout signal of the CMOS camera sensor. In this way, a ^¬ be Sonder good homogeneity of brightness distribution of the image of the camera sensor can be realized without a synchroni- sation is required. Very high frequencies in the driving of the light-emitting component can be achieved in that the electrical capacitances are small. Small electrical capacitances are achieved, in particular, by shorter line ^lengths between the drive device and the component. For this purpose, the control device can be arranged very close to the component. For example, the drive device can be integrated together with the component in a substrate, in particular in a silicon substrate.

Another advantageous development of the method provides that the drive signal of a row- or column-wise modulated readout signal of the CMOS camera sensor is synchroni ^¬ Siert. In this way it is advantageously a require- alteration reduce a frequency of the drive signal of lichtemittie ^¬ emitting component. This can be justified by the fact that the light emitting device is switched on each time ^¬ as soon as a read operation of a line or column of the image of the CMOS camera sensor begins. In this way, sufficient brightness of the image of the CMOS camera sensor is realized. A further advantageous development of the method provides that the synchronization of the pulse-width-modulated control signal of the light-emitting component and the Zei ^¬ len- or column-modulated readout signal of the CMOS camera sensor on rising edges of the line or column-modulated readout signal of the CMOS camera sensor is carried out. In this way a simple Syn ^¬ chronization of the two signals and an efficient operation of the light emitting device can be provided.

A further advantageous development of the method provides that the synchronization of the pulse-width-modulated control signal of the light-emitting component and the pulse-width-modulated readout signal of the CMOS camera sensor is performed on rising and falling edges of the row-wise or column-wise modulated readout signal of the CMOS camera sensor. In this way, a particularly effi ^¬ cient operation and good control of brightness of the light-emitting device can be provided.

A further advantageous development of the method is characterized in that the light-emitting component is a matrix LED with a plurality of light-emitting pixels which are each driven with their own pulse-width-modulated drive signal. A ^¬ the individual pixels are controlled Here, each with its own PWM driving signal to ^¬ advantageous, whereby it is provided for the read-out image information by the camera sensor a high uniformity. A further advantageous development of the method provides that the pulse width modulated drive signal of the light ^¬ emitting device is formed with variable electric currents, wherein the current value of the pulsweitenmodulier ^¬ th driving signal of the light emitting device currency rend of reading an image of the camera sensor is kept constant. In this way advantageously a Hellig ^¬ keitsbereich the light emitting device without the danger of color locus to be controlled. In a further embodiment, the component is additionally controlled in addition to the pulse-width-modulated drive signal A with a DC drive signal C. So that the luminance of the device ^¬ incident light can be changed by increasing the DC control signal C in a simple and fast way, without duty having to change a frequency or an amplitude of the pulse width modulated drive signal A.

In another embodiment, the DC control signal C is changed depending on a brightness of a surrounding area to be illuminated, in particular at remo ^¬ mender brightness of the environment increases. Thus, a simple and rapid readjustment of the brightness of the light can be achieved ^¬ it to allow the recording of images with good quality by the camera sensor regardless of the ambient light. For this purpose, a brightness sensor can be provided which detects the brightness and forwards a value for the ambient brightness to the control device.

In a further embodiment are the pulse width modulated drive signal A and the DC drive signal C changed ^¬ changed to vary the brightness of the emitted light at a constant color point of the emitted light from the device. Thus, with a change in the ambient brightness, the illumination of the environment can be kept constant without changing the color location. In a further embodiment, the pulse width modulated drive signal A and the DC drive signal C are changed in such a way that the lowest possible power consumption and / or the lowest possible heating of the device are obtained. For this purpose, the control device uses, for example, corresponding characteristic curves, maps or calculation methods. In another embodiment, the pulse width modulated drive signal and / or the DC drive signal are changed ^¬ changed in order in a changing environment brightness constant brightness of the illuminated by the component environment or the illuminated by the component object with the lowest possible power consumption and / or the least possible heating to get the component. As a result, an efficient control of the component can be achieved. Technical functionalities and advantages of the method for driving a light-emitting component result analogously from corresponding technical functionalities and advantages of a drive device for a light-emitting component.

The described characteristics, features and advantages of this invention as well as the manner in which they are achieved will become clearer and more clearly understood in connection with the following description of the exemplary embodiments, which will be explained in more detail in connection with several figures.

In the figures: shows a schematic representation of a first embodiment of the method according to the invention for driving a light-emitting component for a CMOS camera sensor according to the rolling-shutter readout principle; a schematic representation of a second embodiment of the method according to the invention for driving a light emitting device for a CMOS camera sensor according to the rolling shutter readout principle; a schematic representation of Hellig ^¬ keitskorrektur using the inventive method in a single LED chip; Figure 4 is a principle illustration of an Hellig ^¬ keitskorrektur by the method according to the invention in a matrix LED chip.

Fig. 5 block diagram of a mobile terminal;

Fig. 6 is a schematic diagram of a

Method for driving a light-emitting component when reading out a CMOS

Camera sensors; and

Fig. 7 is a diagram for a time course of a combined PWM dimming and current dimming.

The used formulations "respectively", "respectively" include in particular the wording "and / or". When using a light-emitting component in the form of LEDs for a read-out of a CMOS camera sensor, which operates on the Rolling-shutter-readout principle ("CMOS rolling shutter camera sensor"), it can because of the line or column-wise reading of the CMOS camera sensor with a modulated illumination by the

LEDs come to different light and dark areas on the detected image. Thus, in different lines, depending on the phase of the modulated illumination by the LEDs, either a completely bright line or a completely dark line or a mixture of both can be detected. The resulting detected or read-out image can be as Hel ^¬ ligkeitsschwankungen have within the image and can thus appear blurry and out of focus on the viewer. It is therefore proposed a method for driving a light emitting device having a good Bildqua ^¬ formality and an homogeneous illumination of a CMOS Rolling Shutter camera sensor realized in combination with a pulse width modulated operated light-emitting device.

FIG. 1 shows in a greatly simplified manner a principal mode of operation of a first embodiment of the method according to the invention for driving a light-emitting component in a row-wise or column-wise readout of a CMOS rolling shutter camera sensor, where A is the pulse-width-modulated control signal of the LED and B denotes the row-wise or column-by-column readout signal of the CMOS rolling shutter camera sensor. The frequency of the line-wise or column-wise readout signal of the CMOS rolling shutter camera sensor is usually in the kHz range. Recognizable in the figure is a readout of three lines of the CMOS rolling shutter camera sensor.

As shown in FIG. 1, the pulse-width-modulated drive signal A for driving the light-emitting component in the form of LEDs has at least one rectangular shape with a maximum current value in the case of a row-wise or column-wise readout signal B of the CMOS rolling shutter camera sensor , wherein the light emitting device in the current flow is being ^¬ on and emits light. In this case, a frequency of the pulse width modulated drive signal A of the lichtemittie ^¬ emitting component is a defined multiple of the frequency of the row-wise or column-wise readout signal B of the camera sensor. As a result it is ensured in this manner that the CMOS camera sensor during readout of a Zei ^¬ le or a column of light from the light emitting device detected.

This functional principle can be expressed mathematically as follows: f LED> f SENSOR with: f LED Frequency of the pulse-width-modulated actuation signal

A of the light emitting device fSENSOR frequency of the row or column have Auslesesig ^¬ Nals B of the CMOS camera sensor, it has been found that in the case that the frequency of the pulse width modulated drive signal A of the lichtemittie ^¬ emitting component is sixteen times greater than the frequency of the readout signal B of CMOS Rolling shutter camera sensor, although it may still come to inhomogeneities between individual lines or columns of the camera sensor of about seven percent, a picture quality but can be useful or satisfactory. The frequency of the readout signal specifies the frequency with which a line or a column of the camera sensor is read out.

Ideally, the frequency of the pulse width modulated drive signal A of the light emitting device should be twenty times the frequency of the readout signal of the CMOS rolling shutter camera sensor in order to achieve good homogeneity in the entire image of the camera sensor.

2 shows a basic mode of operation of a further embodiment of the method according to the invention for driving a light-emitting component in the form of LEDs in the case of a line-wise or column-wise readout of a CMOS rolling shutter camera sensor. It can be seen in this case that the pulse-width modulated drive signal A of the light-emitting component is synchronized with the line-wise or column-wise readout signal B of the CMOS rolling shutter camera sensor at rising edges of the readout signal B of the camera sensor.

In this way, requirements for a frequency of the pulse-width-modulated drive signal A of the lichtemittie ^¬ ren device can be reduced, wherein a frequency of the drive signal A of the light emitting device must be equal at least as a frequency of the readout signal B of CMOS rolling-shutter camera sensor , This can be suppressed by the following mathematical relationship of ^¬: fLED - fSENSOR

A further, not shown in figures variant of the Ver ^¬ driving provides that the pulse width modulated Ansteuersig ^¬ nal A of the light emitting device at rising and accumulating flanks of the readout signal B of CMOS Rolling shutter camera sensor is synchronized.

The operation of the light emitting device in a PWM mode with a pulse width modulated drive signal has not only advantages in a CMOS rolling shutter camera sensor but also in a CMOS global shutter camera sensor, a predictable and homogeneous Farbvertei ^¬ ment and good image quality to realize.

In both of these technologies (rolling shutter and globalization bal shutter) is so far the problem that the brightness correction is achieved by a current dimming of the light emitting device due to stromabhängi ^¬ gen properties of LED chips, in particular blue LED - Chips and their converters cause a change in the color location.

The predictability of the color locus is particularly important in a matrix LED chip with multiple light-emitting pixels. Here, many individual LED chips are driven separately to selectively illuminate and capture scenes with the CMOS camera sensor. Current dimming of the light-emitting component can lead to color inhomogeneities between the individual pixels during detection with the CMOS camera sensor and thus to color inhomogeneities of the entire image, which are hardly compensable with known processing algorithms. By a PWM dimming preferably with a rectangular arrival control signal instead of a current dimming the brightness correction of the current value of the drive signal A of the lichtemit ^¬ animal forming device 100 can always be maintained constant at one of a completeness-ended image of the camera sensor 200 reading. Thus, the current-dependent color locus shift can advantageously be avoided, and thus a requirement on the image algorithm, which composes the entire image from the individual lines, can be reduced. This in particular by the fact that no additional color corrections must be made in the image.

When using a pixelated light-emitting device, the proposed PWM dimming of the individual pixels in the matrix enables better color homogeneity within the matrix, which also results in better color homogeneity in the image of a scene. Thus, different "color spots" are avoided in the recorded image, which can be corrected only with great effort with the help of Bildal- rithm.

FIGS. 3 and 4 show brightness correction by means of the PWM mode in a single LED chip and in a matrix LED. As illustrated in FIG. 3, in the case of the single LED chip, the color location (gray level) remains the same for three different pulse width modulated drive signals. For the matrix LED chip, as shown in FIG. 4, the PWM dimming of the individual elements (pixels) of the matrix results in a uniform color homogeneity (gray level) within the matrix without "color spots".

A development of the method provides that, in addition to the above-described PWM dimming for brightness correction, a current dimming, ie a current-variable operation of the pulse-width-modulated drive signal A of the light-emitting component is undertaken. Due to this combination, the brightness range associated with the flash Illumination of the CMOS camera sensor can be achieved by the light-emitting device can be extended.

Namely, the brightness range is down in pure current dimming of the light-emitting device, i. limited to low electrical currents out. In fact, if the electrical currents are too low, electronic artefacts, for example due to tolerances of the drivers, are more pronounced or may not be adjustable under certain circumstances.

In a combination of current dimming by PWM dimming a finer gradation of the brightness of the image of the camera ^¬ sensors is possible. Thus, dynamics and accuracy can be improved by combining PWM dimming and power dimming. Due to the larger brightness range, a recording accuracy of the camera sensor can be advantageously optimized.

In addition, the proposed method advantageously also low brightnesses of the image of the camera sensor can be read without artifacts of the LED chips, which occur in the conventional exclusive power dimming and the semiconductor owed negative effect on the image. The proposed PWM dimming a mittle ^¬ re temperature of the light emitting device can be further reduced and thus efficiency is increased. The color Tempe ^¬ temperature can be kept stable, that in one period of a cooling phase is contained, which is not the case with conven- tional current dimming.

The method for driving a light-emitting component 100 as flash illumination (flash light) in a mobile terminal 300 (for example a smartphone) can be used particularly advantageously.

5 shows a schematic block diagram of a derarti ^¬ gen mobile terminal 300 with a light-emitting construction element 100, which is driven by a drive device 110 according to the above-mentioned principles. It can be seen further, the CMOS camera sensor 200 of the mobile terminal 300. The driver 110 is preferably as an electrostatic ^¬ African unit formed which realizes the method according to the obi ^¬ gen principles. The control device 110 has, for example, a data memory 600 in which characteristics, maps and / or control methods for controlling the component 100 are stored.

For example, the driver 110 together with the device 100 on a common substrate 500 is arranged or integrated in ^¬ the substrate 500th For this purpose, at least one part, in particular the entire drive device 110, can be integrated in the substrate 500 as an integrated circuit. As a result, electrical line lengths between the component 100 and the drive device 110 are reduced. Since ^¬ the electrical capacitances are small, so that the on-control circuit 110 can drive the device 100 with a high Fre ^¬ frequency. The substrate may, for example, comprise a semiconductor material, in particular silicon or silicon. Fig. 6 shows in graphical manner the method 400 for driving a light emitting device 100 during egg ^¬ nes read out of the CMOS camera sensor 200.

In a combination of PWM dimming and current dimming, a PWM drive signal A and a DC drive

Drive signal C used to drive the light emitting device.

FIG. 7 shows a diagram with time profiles of FIG

Amplitudes of the currents of a pulse width modulated drive signal A and a DC drive signal C over time t. The amplitudes of the PWM drive signal A and the DC drive signal C add up to a total Drive signal G. The pulse width modulated drive signal A is shown in the form of a dashed line. The

DC drive signal C is shown as a dotted line Darge ^¬ . The total drive signal G is shown as a solid line.

In the present example, the PWM drive signal A remains unchanged over time t. The DC drive signal C is increased from the first time tl from a first value Cl to a second value C2.

By combining the PWM drive signal A with the

DC drive signal, a brightness of the compo ^¬ element can be changed independently of the frequency of the PWM drive signal A and independent of the duty cycle of the PWM drive signal A. This allows increased flexibility in the exposure of an environment or an object and in the recording of an image of the environment or the object with the camera sensor. Furthermore, a more precise control of the brightness of the light of the component can thereby be achieved, even if the control device has a constant frequency. Thus the brightness of the light emitted by the component light can be achieved by increasing the DC control signal C in a simple and fast way ^¬ le, without duty having to change a frequency or an amplitude of the pulse width modulated drive signal A.

By changing the DC drive signal C, a basic brightness of the light-emitting component 100 can be changed, in particular increased. The change, in particular ^¬ sondere increasing the basic brightness of the device emit light ^¬ is particularly at night and for a pre ^¬ zise set different light intensities with very small differences in brightness advantage. For example, the DC control signal C can be varied depending on egg ^¬ ner brightness of a surrounding area to be illuminated, in particular with decreasing brightness of the environment increases become. Thus, a simple and rapid readjustment of the brightness of the emitted light from the component can be achieved in order to achieve the most uniform possible brightness of an environment or an object. This allows the recording of good quality images by the camera ^¬ sensor regardless of the ambient light. For example, a light sensor 700 may be provided which detects the brightness of the ambient light and forwards a value for the brightness of the ambient light to the drive device 110.

Furthermore, the drive device 110 can have a data memory 600 with characteristic curves, tables and / or control methods with which the pulse-width-modulated drive signals A and DC drive signals C to be used for different ambient brightnesses are stored in order to achieve an approximately constant brightness with the light of the To get Bauele ^¬ mentes illuminated environment or the illuminated object.

For example, exposures of an object or environment and thereby exposures of the object and the environment with the camera sensor at night or in low light conditions such as exposure to light may occur. Recordings in an interior are enhanced by a PWM dimming and a DC dimming.

For example, these advantages can be when shooting a Bil ^¬ of a large brightness range and great detail (High Dynamic Range) by the camera sensor is ^¬ sets.

Furthermore, using the combination of the PWM driving signal A and the DC control signal C a desired Varia ^¬ tion of the color point can be achieved. This allows for increased flexibility in lighting and recording with a camera sensor. In a control of the component only with the PWM drive signal A, the color locus of the emitted light in a light-emitting diode, ie an LED chip as a component accordingly the amplitude current of the PWM drive signal. In a combination of PWM drive signal A and DC drive signal C, the color locus adjusts itself at a light ^¬ de depending on the DC drive signal from the amplitude Ström the PWM drive signal A and the duty cycle of the PWM drive signal A.

Thus, the pulse-width-modulated drive signal A and the DC drive signal C can be changed in order to vari ^¬ at a desired constant color location of the emitted ^¬ th light from the component the brightness of the emitted light. In particular, with increasing darkness of the environment Conversely ^¬ bright, the brightness of the light of the component can be increased at constant color point of the emitted light. Thus, the brightness of the illuminated with the light of the component In order ^¬ gebung can be kept constant with a change in ambient brightness, without changing the chromaticity. To detect the ambient brightness of the

Light sensor 700 used, which is connected to the drive device 110.

The control device 110 can have characteristics, tables and / or control methods via the data memory 600, with which for predetermined color locations of the light emitted by the component for different ambient brightnesses or for different brightnesses of the light of the component to be used pulse width modulated drive signals A and DC -Ansteuersignale C are stored in order to obtain a ^¬ approaching constant brightness of the illuminated with the light of Bauelemen- tes environment or different brightnesses of the light of the component without the color location of the light of the component changes.

In addition, the combined PWM dimming and DC dimming method can be used in order to produce a light with the same component color point with different brightness with the lowest possible power consumption. The drive device 110 can via the data memory 600 via Have characteristic curves, tables and / or control methods with which for predetermined color locations of ^¬ th light emitted by the component for different brightnesses of the sent ^¬ th light to be used for lowest power consumption pulse width modulated drive signals A and DC drive signals C are stored , Thus, a current ^¬ efficient control of the device for light with moving ^¬ chem locus but to achieve different brightness of the light.

In addition, the combined PWM dimming and DC

Dimming method can be used to generate the least possible ge ^¬ ing heating of the device, a light with the device with the same color location and different brightnesses. The driving means 110 may include the data memory 600 via characteristic curves, tables and / or control method, with which for given color locations of the ^¬ element emitted by construction light of different brightness of the light, the pulse width modulated to be used for a lowest heating of the component drive signals A and DC drive signals C are stored. Thus, a control of the device with different Brightness, ^¬ th of light but to achieve the same color point of light with mög ^¬ lichst low heat. In summary, the invention provides an efficient technical concept ^¬ ULTRASONIC prepared which provides an improved read-out of an illuminated by a light emitting device camera sensor. An imaging quality of images acquired by means of the camera sensor is thereby advantageously increased.

Although the invention has been further illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention. LIST OF REFERENCE NUMBERS

100 light-emitting component

110 drive device

200 camera sensor

300 mobile terminal

400 process step

500 substrate

600 data storage

700 light sensor

A drive signal light emitting device

B Readout signal Camera sensor

C DC drive signal

G total drive signal

Claims

PATENTA'S TEST

A method of driving a light emitting device (100) in a readout of a CMOS camera sensor (200), comprising the step of:

Operation of the light emitting device (100) in PWM mode with a pulse width modulated drive signal (A).

2. The method of claim 1, wherein the CMOS camera sensor

(200) is a working according to the rolling shutter readout CMOS camera sensor, and wherein a frequency of the pulse width modulated drive signal (A) of lichtemit ^¬ tierenden component (100) at least equal or defi ^¬ ned greater than a frequency of a line or column by column modulated readout signal (B) of the camera sensor

(200) is.

3. The method of claim 2, wherein the frequency of the pulse width modulated drive signal (A) of the lichtemittie ^¬ generating device (100) is greater than the sixteen times the frequency of the line or column-modulated readout signal (B) of the CMOS camera sensor (200).

4. The method of claim 2, wherein the frequency of the drive signal (A) of the light emitting device (100) is greater than twenty times the frequency of the line or column-modulated readout signal (B) of the CMOS camera sensor (200).

5. The method according to any one of claims 1 to 3, wherein the

Pulse width modulated drive signal (A) of the lichtemittie ^¬ generating device (100) and a line or column-modulated readout signal (B) of the CMOS camera sensor (200) are synchronized.

6. The method of claim 5, wherein the synchronization of the pulse width modulated drive signal (A) of the light emitting ^¬ tierenden device (100) and the row or column is modulated read-out signal (B) of the CMOS camera sensor (200) on rising edges of the line or column-modulated readout signal (B) of the CMOS camera sensor (200) is performed.

The method of claim 5, wherein the synchronization of the pulse width modulated drive signal (A) of lichtemit ^¬ tierenden component (100) and the pulse width modulated readout signal (B) of the CMOS camera sensor (200) modulated on stei ^¬ ing and falling edges of the line or column Readout signal (B) of the CMOS camera sensor (200) is performed.

Method according to one of the preceding claims, wherein a single LED chip is driven as the light-emitting component (100).

Method according to one of claims 1 to 7, wherein the light-emitting component (100) is a matrix LED having a plurality of light-emitting pixels, which are each driven with its own pulse width modulated drive signal.

Method according to one of the preceding claims, wherein the current value of the pulse width modulated drive signal (A) of the light emitting device (100) is kept constant during ei ^¬ nes reading a complete image of the CMOS camera sensor (200).

Method according to one of the preceding claims, wherein the component (100) in addition to the pulse width modulated drive signal (A) with a DC drive signal (C) is driven.

The method of claim 11, wherein the DC drive signal (C) is changed in response to a brightness of an environment to be illuminated, in particular is increased with decreasing brightness of the environment.

13. The method according to any one of claims 11 or 12, wherein the pulse width modulated drive signal (A) and the DC drive signal (C) are changed to at a constant color location of the component (100) emitted

Light to vary the brightness of the light emitted by the device (100) ^¬ Deten light.

14. The method of claim 13, wherein the pulse width modulated te drive signal (A) and the DC drive signal

(C) can be changed in such a manner that a ge possible ^¬ ringer power consumption and / or the lowest possible heating of the components (100) are obtained.

15. The method according to any one of claims 11 to 14, wherein the pulse width modulated drive signal (A) and the ^{DC ¬} current drive signal (C) are changed to change the brightness of the emitted light from the device (100) at a changing ambient brightness, to maintain a constant brightness of the device (100) to achieve be ^¬ light environment or the object with ge possible ^¬ ringem power consumption and / or with a minimal heating of the components (100).

16. Drive device (110) for a light-emitting ^{component ¬} (100) in combination with a CMOS camera sensor (200), wherein the drive means is formed in a PWM mode with a pulse width modulated drive signal at a readout of the CMOS camera sensor (200 ) to be operated.

17. Drive device (110) according to claim 16, wherein the

CMOS camera sensor (200) is a CMOS camera sensor (200) operating on the rolling shutter readout principle, and wherein a frequency of the pulse width modulated drive signal (A) of the light emitting device (100) is at least equal to or greater than a frequency a line-or column-wise modulated Auslesesig ^¬ nals (B) of the CMOS camera sensor (200).

Drive device (110) according to claim 16 or 17, wherein the current value of the pulse width modulated drive signal (A) of the light emitting device (100) during ei ^¬ nes reading a complete image of the CMOS camera sensor (200) is kept constant.

Mobile terminal (300) with a CMOS camera sensor (200), with a light-emitting component (100) and a drive device (110) according to one of Claims 16 to 18.

The mobile terminal (300) according to claim 19, wherein the light ^¬ emitting device (100) is a single LED chip or a matrix-LED having a plurality of light emitting pixels which are driven control signal each with its own pulse width modulated arrival.