BE1024121B1 - Control unit for adjusting a white point in a projection system - Google Patents

Abstract

A light projection system for generating an image with three primary colors. The system comprises a first blue laser source that emits a first beam in a fourth waveband, the first blue laser source having a first laser control, a second blue laser source that emits a second beam with a central wavelength and a fifth wave region, the second blue laser source having a second laser control , a substrate with a wavelength conversion element for emitting light at a plurality of wavelengths after absorption of a light beam at an excitation wavelength in a fifth waveband of the second blue laser source, a beam combining means for combining the combined first beam and the converted beam, which combination results in a white bundle. The projection system comprises an optical control unit for measuring the relative intensity of the first, second and third wavebands of the white beam.

Description

Control unit for adjusting a white point in a projection system

The present invention relates to an optical sub-assembly, a projector and a method for operating a projector, a controller for controlling a projector and a method for controlling a projector.

Background

Projection technology increasingly uses solid state light sources instead of conventional lamps, for example the use of lasers in a single-chip DLP projector, three-chip DLP projectors or other projectors with three image sensors (LCD, LCoS, ... ).

Laser-based solid state projectors can be divided into two main categories: • Full laser projectors (using direct red, green and blue lasers) • Laser phosphor projectors (using the blue laser to excite a wavelength conversion material to generate the three primary colors)

Currently, the full laser projectors are mostly ultra-clear projectors that target the niche market of digital cinema (DC). Laser phosphor projectors mainly have a lower light output, ie below 12,000 lumens and are therefore sold in markets outside of digital cinema. However, recent improvements in phosphorus technology enable laser phosphor projectors to achieve even brightness levels of up to 20,000 lumens, and possibly higher.

High brightness and color performance are important because a digital cinema projector must project images according to the DCI standard, including, for example, a typically wider color gamut.

In markets outside of digital cinema, a different color gamut of the projector can be set as the REC709 color gamut. But it is very important to mention that REC709 is only a recommendation, not a standard. Therefore, the color performance of the projectors can vary greatly both for the color point of the primary colors and for the color-to-white ratio and the white color point. The DCI standard is much stricter and defines the color gamut and the white point of a Digital Cinema projection system. Some tolerances are permitted through low tolerance boxes expressed in a color scheme for the white color point and the color points of the primary colors.

A comparison between the REC709 color gamut and the DCI color gamut is shown in Figure 1.

Current laser-phosphor-3-chip projectors generate red, green, and blue primary colors using blue lasers to excite a phosphor-wavelength converter and to generate yellow light. Direct blue laser light is added to the phosphor yellow light to create a white source. Blue lasers are preferred instead of blue LEDs for phosphorus excitation due to the smaller laser light entendue. Sometimes additional red lasers or red LEDs are added to improve the red content. The typical optical spectrum of such a white light source consisting of direct blue lasers and yellow phosphorescent material is shown in Figure 2.

The color point for the white laser + phosphor light source will vary depending on a number of design choices. In addition, with respect to the blue primary color point, the wavelength can vary in the 440 nm and 470 nm intervals for direct blue lasers and one wavelength or a combination of different wavelengths can be used in this interval. The wavelength of the blue lasers can have some influence on the white point, although their intensity or power level has a much greater impact. The selection of the blue laser has an impact on the location of the blue primary color point, in other words, the lower left corner of the color gamut.

The blue laser + yellow phosphor architecture has become very popular for projectors in the markets outside of digital cinema due to its reduced complexity and the right balance between performance and costs. The wavelength converter, for example, is only one type of phosphorescent substance that is used to make both the red and the green component. In addition, yellow phosphorescent materials with very good performance (for example, high conversion efficiency, chemically stable, good deaf performance, etc.) are readily available and the most popular example is the YAG: Ce phosphor used in white LEDs for lighting and background lighting applications. However, it is a well-known fact that the use of red phosphorescent substances is not easy, mainly due to the fact that red phosphorescent substances have poor thermal behavior and are extinguished at temperatures much lower than those observed for good yellow phosphorescent substances . Also, the conversion efficiency of the red phosphorescent substances is much lower than that of a yellow phosphorescent substance (e.g. 30-35% compared to 60-65%). Hence, having a high-performance yellow phosphorescent substance with a significant red content has in many cases become the preferred solution.

However, for DCI-compatible projectors, this very popular solution of only using blue lasers and a yellow phosphorescent material proved to be rather limiting and additional improvements were needed.

To have a DCI-compatible projector when using such a white direct blue laser + yellow phosphor source, a number of steps must be performed.

The first step is to have the original red, green and blue primary colors according to the DCI spec. For most of the 3-chip projectors, splitting the light is generated by the light source in the three primary colors, which takes place in the imaging module of the projector, executed by the Philips prism as shown in Figure 3. The Philips Prism is also responsible for the initial filtering of the light. This filtering is the result of the typical difference of incidence (AOI) on the Philips prism coatings for incoming and outgoing light. The precisely influenced wavelength ranges depend on the coating design, but a typical case is that, for example, a dip around 490-500 nm (less visible in Figure 3) and around 575-600 nm is created.

However, the red and green primary colors obtained in this way are still too wide to be DCI compatible. The color points are not in the corresponding DCI tolerance boxes. Additional filtering in the green-red transition interval that is performed with a sharp filter is needed with the effect that is shown schematically in Figure 4.

The wavelength interval between the green and red wavelengths (hence yellow wavelengths) where the image processor makes the split between red and green results in a considerable amount of light loss.

The sharp filter effect shown in Figure 4 is only an example. In reality, the characteristics of the filter will have to be adjusted to the exact phosphor spectrum and the exact specifications of the dichroic filters in the prism to correct the color points of the primary colors so that they are DCI compatible.

Due to the large difference between the optical spectrum of a Xenon lamp and a yellow phosphorescent material, the light losses due to the use of a sharp filter with a Xenon lamp are very different from those of a blue laser + yellow phosphorescent white source. In the case of the Xenon lamp, this is usually 8% (in lumen). While in the case of blue laser + yellow phosphorescent white source this is around 18% (in lumen).

In addition to this significant reduction in brightness through the sharp filter for the specific case of a laser phosphor light source, the lack of red light and the excess of green light in the spectrum is another source of brightness reduction.

As a result, the biggest problem with using the blue laser + yellow phosphor architecture for a DCI-compatible projector (in addition to the significant decrease in brightness through the sharp filter) is the lack of red light and the excess of green light in the typical spectrum of a yellow phosphorescent substance. Although this may not be a problem for projectors where the color-to-white ratio is not a critical parameter, it is a major problem for DCI-compatible projectors where the white color point (and therefore the red-to-white ratio) very well defined in the DCI standard.

To solve this problem and get the white color point to the DCI target value, the excess of green light (and possibly also blue) must be removed electronically. The same procedure is also used in current projectors based on Xenon and Mercury lamp. But the losses due to these electronic corrections in the laser-phosphorescent-based projectors are much higher than what is usually the case for a Xenon or Mercury lamp-based projector. With typical values of 30% decrease in brightness as a result of the electronic correction, having a phosphorescent substance with such a limited red content appears to be a very serious problem.

To address the lack of red in the yellow phosphor spectrum, a solution that is typically referred to as "red-assisted laser phosphor source" has been proposed. In this case, an additional light source (direct red laser or red LEDs) is used to increase the red color that is produced. This additional light source is added to the existing blue laser + yellow phosphor solution without typically changing the type of phosphorescent substance used.

This is a very good solution to increase the red content and to reduce the losses due to color correction, but it still does not minimize the possible brightness losses that are required to achieve the DCI specification or other color gamut specifications or other standard white point, or a combination of these.

Summary of the invention

An object of the present invention is to provide an optical sub-assembly for a projector designed to interact with a red laser and a phosphor source with the advantage that losses are reduced or minimized. Embodiments of the present invention reduce or minimize the light losses that occur when, for example, a yellow phosphorescent material is used. These losses can occur at different stages in the light path, such as in the Philips prism, due to electronic correction, due to a sharp filter and / or any combination thereof. Similar problems may arise with other color splitting and recombination engines for 3-chip projectors, DLP or also LCOS or LCD, for example with a color splitting dichroic mirror and a recombination X-cube.

Embodiments of the present invention provide the advantage of a smaller, more compact, cheaper projector with a lower need for cooling, particularly for a wide-gamut color performance. Embodiments of the present invention are particularly suitable for a specific standardized white color point such as a DCI white color point.

An advantage of embodiments of the present invention is to link the color performance of the projection system to a color gamut target as given by DCI or greater with low or minimal light loss.

Embodiments of the present invention are particularly advantageous when used as a 3-chip projector architecture with continuous white light illumination, i.e., one illumination per projector, but a combination of 2 or more is included within the scope of the present invention.

In a first aspect, the present invention provides a light projection system for generating an image with three primary colors, in particular blue, green and red, wherein each primary color is respectively defined by a first, second and third waveband, wherein the light projection system the following comprises: a first blue laser source that emits a first beam in a fourth waveband, the first blue laser source having a first laser control, - a second blue laser source that emits a second beam with a central wavelength and a fifth waveband, the second blue laser source having a second laser control has a substrate with a wavelength conversion element for emitting light at a plurality of wavelengths after absorption of a light beam at an excitation wavelength within a fifth waveband of the second blue laser source, the substrate being positioned in such an optical path of the second beam that light that by huh The wavelength conversion element transmitted or reflected by it results in emission of a converted beam with a waveband comprising at least the second and third wavebands, a beam combining means for combining the combined first beam and the converted beam, which combination results in a white bundle; characterized in that the projection system further comprises an optical control unit for measuring the relative intensity of the first, second and third wavebands of the white beam.

The optical control unit receives values from at least one light sensor. The control unit has several advantages such as assisting with setting and adjusting the white point, compensation for aging etc.

The light sensor is preferably a multi-band sensor or a plurality of sensors for different wave bands, the sensor being configured to measure the intensity of wavelengths included in the first, second and third wave bands. The multiband sensor is preferably configured to detect any difference in the light spectrum between a laser light and a converted beam.

The optical control unit can receive light by means of a folding mirror, which is placed in the optical path of the white beam, in such a way that about 0.5% of the light is reflected to the light sensor. The low level of light loss is an advantage. The light sensor can be at least one of a photodiode sensor, photoresistor, organic photoreceptor, spectrometer, photo amplifiers, CCD or CMOS sensors.

The projection system preferably comprises a processing unit configured to communicate with the optical measuring unit. The processing unit has a processing unit such as a microprocessor or an FPGA and can therefore perform arithmetic calculations.

Preferably, the foldable mirror is configured to be retracted in and out of the white bundle, and preferably the foldable mirror is mounted on an actuator controlled by the processing unit.

The wavelength conversion element emits light at a center of gravity wavelength <560 nm - a GRTZC <16%.

Light emitted by the wavelength conversion element can have a green content of> 65%.

The green content can for example be <75%, optionally <80%.

It may be advantageous to have a third red laser source that emits a third beam in the third waveband, the third red laser source having a third laser control as this gives more control over the color gamut.

The present invention is very suitable for a 3-chip projector architecture.

The first or third waveband is wider than the waveband of any individual laser source, since the lasers have a narrower bandwidth.

Blue or bluish light can be emitted from the wavelength conversion element in the wavelength 480-500 nm and the blue laser can be in the wavelength 440-470 nm wavelength.

A red content is preferably <30% and optionally> 20%, the percentage values referring to relative energy contributions of the converted light from the wavelength conversion element in a given wavelength range compared to the entire light spectrum of the wavelength conversion element that is 100% is taken. A green content is a portion of light spectrum of the light emitted from the wavelength conversion element that gales into the green waveband.

The third green waveband can be in the range 495 - 575 nm.

The GRTZC refers to light that makes colors unsaturated and makes the color range smaller.

A red content in a light beam is the relative portion of the wavelength conversion element spectrum that goes into the red waveband. The red waveband has light from the red laser and an added amount of red or reddish light from the wavelength conversion element for development, an upper limit of the reddish light is reached if the color point moves from red to a smaller color gamut.

The red or reddish light can be orange light in the range of 595 - 620 nm.

The Blue light + Green light + Red light is up to 100% of the light of the wavelength convers i e element.

A sharp filter can be provided for reducing light intensity of wavelengths in the wavelength 570 - 600 nm. The sharp filter (370) can be selected to reduce light intensity in the range of 10 - 15% or 10 - 20%.

At least one variable waveband reduction filter mounted on an actuator can be provided in the optical path of the white beam, and wherein a movement of the variable waveband reduction filter between a first and a second position results in a change in the transmitted waveband of the white beam from a first to a second transmitted intensity, so as to adjust a projector white point.

The variable waveband reduction filter can be a first waveband reduction filter, a second waveband reduction filter or a third waveband reduction filter, such that it is configured to change the intensity of wavelengths included in the first, second or third wave bands, respectively.

The or any sharp filter and the variable waveband reduction filter can be combined with a combined variable filter.

A first side of the variable filter can be coated with a narrow band sharp filter and a second side of the filter is coated with a variable waveband reduction filter.

The variable second waveband reduction filter can be configured to reduce the intensity of wavelengths included in the range of 510-570 nm.

The actuator can be controlled by a processing unit. The actuator may comprise a rotation platform for rotating the variable second waveband reduction filter about the optical axis or at least one translation platform for moving the variable second waveband reduction filter in a direction perpendicular to the optical axis.

The variable second waveband reduction filter may comprise a coating provided with a pattern with an increased density of green-reducing patterns, the direction of the density increase being adapted to the direction of movement of the actuator such that the intensity of the second green spectral band can be adjusted.

The variable second waveband reduction filter can have at least one of a rectangular continuous green reduction coating that provides a linear, controllable decrease in the coated area via translation, a filter with a rectangular stepwise reduction coating that provides a step-controlled decrease in the coated area via translation, a round filter that provides linear, controllable decrease in the coated area via rotation or a round filter that provides linear decrease in steps in the coated area via a rotation of the filter.

The wavelength conversion element is a phosphor since phosphorescent materials have a high power class that can operate at, for example, 50 W / m no. The phosphorescent material may, for example, be of the YAG: Ce type for a yellow phosphorus. Alternatively, the phosphorus may be of the LUAG: Ce type for a green phosphorus. For lower power classes, for example, Quantum dots (quantum dots) can be used for the wavelength conversion element.

The processing unit is preferably configured to communicate with the optical control unit for measuring the relative intensity of first, second and third wavelength bands of a white beam, the processing unit being further configured to calculate a change in the control levels of at least at least one of the first to third laser beams and the control levels of the at least one variable waveband reduction filter according to the relative intensity of the first, second and third wavebands of the white beam to control a white point shift, and wherein the first to third laser controls are independently regulated so as to adjust the light intensity of each of a first and second blue laser source independently of the light intensity of a red laser source.

The optical control unit is preferably arranged to monitor various contributions in any, some or all of the wavebands. The optical control unit may be arranged to monitor both the laser light and the wavelength conversion element light contribution in the blue waveband.

A variable blue and red reduction filter can provide further adaptability. The variable blue and red reduction filter further reduces the reddish and bluish light of the wavelength conversion element going into the red and blue channel. The blue and red-reducer can comprise an actuator such that the amount of blue and red light transmitted through the filter can be adjusted by moving the position of the filter.

Each laser source comprises a series of individual lasers, wherein the intensity of each individual laser is controlled by its laser control and wherein each laser is configured to be pulsed by its associated laser control. Bundle homogenization optics can be provided as well as a stimulant.

The present invention also provides an optical assembly for a light projection system for generating an image with three primary colors, in particular blue, green, and red, each primary color being respectively defined by a first, second and third waveband, the optical assembly for use with a first blue laser source that emits a first beam in a fourth waveband, the first blue laser source having a first laser control, wherein a second blue laser source emits a second beam with a central wavelength and a fifth waveband, with the second blue laser source second laser control, the assembly comprising the following, having a substrate with a wavelength conversion element for emitting light at a plurality of wavelengths after absorption of a light beam at an excitation wavelength within the fifth wavelength of the second blue laser source, the substrate being in an optical job of the second b undel is positioned such that light transmitted or reflected by the wavelength conversion element results in emission of a converted beam with a waveband comprising at least the second and third wavebands, - a beam combining means for combining the combined first beam and the converted bundle, which combination results in a white bundle; characterized in that the optical assembly further comprises an optical control unit for measuring the relative intensity of the first, second and third wavebands of the white beam.

Laser light from a third red laser source can be provided to emit a third beam from the third waveband, the third red laser source having a third laser control. The present invention provides a method for generating an image with a light projection system with three primary colors, in particular blue, green, and red, wherein each primary color is respectively defined by a first, second and third waveband, the method being the following comprises: - generating laser light from a first blue laser source that emits a first beam from a fourth waveband, the first blue laser source having a first laser control, - generating laser light from a second blue laser source that emits a second beam with a central wavelength and a fifth waveband, the second blue laser source having a second laser control, - generating a converted light beam from a substrate with a wavelength conversion element that emits light at a plurality of wavelengths after absorption of a light beam at an excitation wavelength within the fifth waveband of the second blue laser source, where the substrate is positioned in an optical path of the second beam such that light emitted or reflected by the wavelength conversion element leads to emission of a converted beam with a waveband comprising at least the second and third wavebands, - combining the combined first and third bundles and the converted bundle, which combination results in a white bundle; - characterized by measuring the relative intensity of the first, second and third wavebands of the white bundle.

Laser light can be generated from a third red laser source that emits a third beam from the third waveband, wherein the third red laser source has a third laser control. Any of the laser sources can be a multiple individual laser combined together and can be driven by groups of laser controls such that, for example, each laser control can drive a variety of lasers.

The second blue laser source can be a UV or a bna UV laser source and therefore lie in the UV or bna UV wavelength ranges. This laser light is converted by the wavelength conversion element, so that the specific wavelength range of the excitation light is not so important. Blue lasers of 440-470 nm wavelength are currently an economical choice.

Brief description of the drawings

Figure 1 shows a comparison between the REC709 color spectrum and the DCI color spectrum.

Figure 2 shows a known optical spectrum of a white light source consisting of direct blue lasers and yellow phosphorescent material.

Figure 3 shows the effect of a Philips prism.

Figure 4 shows schematically the effect of an additional filtering in the green-red transition interval performed with a sharp filter.

Figure 5 illustrates an embodiment according to the present invention of optical sub-assemblies and a light source integrated into a projector.

Figure 6 illustrates an embodiment according to the present invention of optical sub-assemblies and a light source integrated into a projector.

Figure 7 shows a comparison between the optical spectrum of a typical green phosphorescent substance used in embodiments of the present invention, as shown in Figures 5 and 6, and a typical yellow phosphorescent substance. Figure 8 shows the spectral characteristics of a typical yellow phosphorescent substance and a typical green phosphorescent substance in the 575-600 nm interval according to an embodiment of the present invention.

Figure 9 shows the spectrum of a system 1) (blue lasers + yellow phosphorescent + red lasers).

Figure 10 shows the spectrum of a system 2) (blue lasers + green phosphorescent substance + red lasers) according to an embodiment of the present invention.

Figure 11 shows DCI color gamut and REC709 color gamut in the color space and respective primary color tolerance boxes where the gamut of the green phosphorescent with blue and red laser is in accordance with an embodiment of the present invention.

Figure 12 shows the green primary color waveband generated by green and yellow phosphorescent materials, the green phosphor spectrum being in accordance with an embodiment of the present invention.

Figure 13 shows the light spectrum of the light emitted by the yellow and green phosphorescent material according to an embodiment of the present invention.

Figure 14 shows the red primary color waveband generated by yellow and green phosphorescent material according to an embodiment of the present invention.

Figure 15 shows the spectrum of the white beam in the projector upstream prior to entering the imager.

Figure 16 shows a known system with bundle-edendue-based method for use with embodiments of the present invention.

Figure 17 shows the addition of a sensor and controller that provided feedback control from the controls to the embodiment shown in Figure 5.

Figure 18 shows an example of the sensitivity ranges of the multi-band sensor as described with reference to Figure 17 according to an embodiment of the present invention.

Figures 19a - 19e illustrate various embodiments of a variable waveband reduction filter.

Figure 20 shows the transmission of a green variable reduction filter combined with a sharp filter in accordance with embodiments of the present invention.

Definitions

In this description, a distinction is made between the primary colors of a standard color range such as REC 709 and a wider color range such as DCI. However, DCI is just one example of a wider color gamut. The embodiments of the present invention can be used for other wider color gamut, for example, for a new and changed DCI color gamut, or, in another example, for color gamut moving closer to Rec-2020, which in itself is apparently unattainable in its strict definition because it requires monochromatic primary colors that are currently only possible with only lasers in each primary color.

In a projection system, the definition of a primary color is complicated because it depends on where in the optical path the primary color is defined, i.e. in each color channel, at the height of the light modulator devices, upstream of the light modulator devices or at the output of the projector. It is often the case in projection systems that the three primary colors are red, green and blue.

In optical terms, a primary color is defined as "One color element of three colors, in an additive imaging system, that can be combined in different proportions to produce any other color." Each primary color is further defined, according to a standard, e.g. DCI standard, through a waveband range.

It is important to note that a primary color is also defined in a standard through its color coordinates. A certain waveband and a certain spectral distribution within this waveband can create a certain group of color coordinates that is the same as that defined in a standard. For example, the group can include two color coordinates such as (x, y) that determine the color point.

There are, however, different solutions with differences in waveband and spectral distributions that can create the same color coordinates, sometimes referred to as "metamerism."

In additive imaging systems, white point is defined as "the color (or color coordinates and luminance) that is produced when the system is sent the maximum RGB code values it can accept" as defined in Color and Mastenng for Digital Cinema by Glenn Kennel , 2006, ISBN-10: 0240808746. Furthermore, the book "DCI specifications and SMPTE standard for screen luminance and chromaticity" specifies that the white point is defined as having color coordinates [0.314 0.351]. However, this definition of white point is optional and the definition also depends on the standard used.

The definition of white point depends on the application. That is why we distinguish between the white point of the projector (or original white point) and the target white point. We define the white point of the projector (original white point) as the target white point when all three color channels provide their maximum level. The target white point is the standard that the projector should reach.

The white point shifts as the offset of the projector's white point with time or with the lighting levels dimmed.

Similarly, we define target primary colors as the primary colors defined by the standard, i.e., DCI standard, and the primary colors (or original primary colors) of the projector as the primary colors provided to each color channel or light modulator device. to become. Original primary colors therefore have no electronic correction.

It is clear that the primary colors of the projector define the white point of the projector, although the target primary colors do not necessarily define the target white point.

A spectral center of gravity is a measure that is used in digital signal processing to characterize a spectrum. It indicates where the "center of gravity" of the spectrum is.

It is calculated as the weighted average of the frequencies present in the signal, determined with a Fourier transformation, with their magnitude as the weights.

Center of gravity wavelength differs from the peak wavelength, mainly because phosphorus spectra are often located asymmetrically around the peak with a longer tail in higher wavelengths.

The center of gravity is more useful than the peak because the green waveband channel occupies a certain broad interval of the phosphor spectrum, so that the "dominant wavelength" achieved, which is the respective color point, i.e. for DCI compatibility. should be coupled more to the center of gravity wavelength than to the peak wavelength.

The center of gravity of a phosphor spectrum can be accurately predicted how the color point would move on a CIE color chart and whether it exceeds the DCI point, for example. And in general, green phosphorescent materials are better than these than yellow phosphorescent materials due to the lower center of gravity wavelength.

A "wavelength conversion element" receives light from a light source, such as a blue laser, and emits light at different wavelengths. Such elements can be made with a phosphorescent substance, with quantum dots or fluorescent dyes. Quantum dot plates / films can withstand around 5 W / cm2 laser power illumination.

Quantum Dots are preferably cooled, for example by a fluid such as air or a liquid. Quantum dots can emit in a considerably smaller band than phosphorescent substances. This makes 3D ~ projectors possible, for example. For example, one can use "6P" small band quantum dots, for example with 100% green content. But even with such quantum dots, it can be important to set or adjust the white point and to use a multi-band sensor with a control and controller and / or processing unit.

Embodiments of the present invention provide a laser + wavelength converter that is phosphorus or something else with the condition that the emission spectrum of the wavelength converter is the same as that specified in the patent.

Color matching in embodiments of the present invention includes removing excess green light generated by a blue laser and yellow fluorescent lighting before the light enters the device, for better cooling and less loss of the contrast ratio and bit levels. A yellow sharp filter may be needed to create a white color gamut such as a DCI color gammate.

Green wavelength conversion elements, such as based on a phosphorescent material, immediately provided illumination with a wide color gamut such as DCI and with a balanced white point, such as the DCI white point, by providing the correct laser power. This has the same advantages as the Color Matching with the addition that it is more efficient.

Extending both concepts to multi-channel projectors provides an advantage that illumination alignment of the white point, for example, can be performed.

Description of the exemplary embodiments

Embodiments of the present invention aim to link the color performance of a projection system to a target color gamut as given by DCI, or greater with low or minimal light losses.

In one embodiment, a laser phosphor light source is proposed for a 3-chip projector consisting of, or comprising: • One or more direct blue lasers • One or more blue lasers, including optional UV or ultra-UV laser around a green wavelength conversion element such as a green excite phosphorescent material • One or more optional direct red lasers • One or more bundle of combining means to combine the different color contributions into a white light beam provided to an imaging processor. • Optionally at least one primary movable waveband reduction filter, preferably blue or red.

In another embodiment of the present invention, a laser phosphor is proposed for a 3-chip projector, comprising: • One or more direct blue lasers • One or more blue lasers, including optional UV or ultra-UV laser around a wavelength conversion element such as a phosphorescent substance to generate a light beam with a waveband conversion element comprising at least one primary color, such as yellow phosphor • Optionally one or more direct red lasers • One or more beam combining means to combine the different color contributions to form a white one light beam provided to an imaging processor. • Optionally at least one primary movable color waveband reduction filter, in particular green, blue or red.

This second embodiment will be described after the description of the first embodiment.

Figures 5 and 6 illustrate two embodiments according to the present invention of optical sub-assemblies and a light source integrated into a projector, using dichroic mirror components as beam combining means in the lighting source, other examples of similar devices being understood by those skilled in the art .

Figure 5 shows controls 2, 4, 6 provided respectively for a blue laser 3, a blue laser 5 and red laser 7. Each laser can be made from a group of lasers whose bundles are combined in an output beam. The blue laser 2 transmits light 2 'in the wavelength range 440 - 470 nm incident on a wavelength conversion element 8, either in transmission (not shown) or in reflection. For the wavelength conversion element excitation, this range can be extended to include UV wavelength ranges. The red laser can emit in the range 630-650 nm although longer wavelengths are also suitable. Optionally, collection optics 9 are provided for collecting the transmitted wavelength conversion element light, e.g. phosphor light. The wavelength conversion element 8 can be a green phosphorescent substance as described below. The wave-converted light beam 2 "emitted by the wavelength conversion element 8 is directed, for example by means of dichroic mirrors 10 and 11, to homogenization optics 12 which serves to create a uniformly rectangular white beam with a certain half-cone angle that is displayed on one or more light valves in the imaging processor Examples of homogenizing optics are groups of fly-eye lenses (also called light bars). Blue laser 5 and red laser 7 emit beams 5 'and 7' directed to the development of optics 13 via a dichroic mirror 30. The combined beams 5 'and T are directed to the homogenizing optics 12, for example via dichroic mirror 11. The output of the homogenization optics 12 is a white beam 14 that impinges on an imaging processor including a TIR prism and Philips prism structure, 16 for example, which splits the white light into three primary colors such as red, green and blue beams each incident on a light valve 18a, 18b, 18C such as a DMD. Reflected light from the DMDs that is modulated in accordance with an image such as a video is reformed by the TIR prism and Philips prism structure 16 to form the projection beam 19 directed by a projection lens 20.

Figure 6 shows a further embodiment with controls 2, 4, 6 provided respectively for a blue laser 3, a blue laser 5 and red laser 7. The red laser can emit in the range 630 - 650 nm although longer wavelengths are also suitable. The blue laser 2 emits light 2 'in the wavelength range 440-470 nm incident on a wavelength conversion element 8, either in transmission (not shown) or in reflection. For the wavelength conversion element excitation, this range can be extended to include UV wavelength ranges. Optionally, collection optics 9 are provided for collecting the transmitted wavelength conversion element light, e.g. phosphor light. The wavelength conversion element 8 can be a green phosphorescent substance as described below. The wave-converted light beam 2 "emitted by the wavelength conversion element 8 is directed, for example by means of dichroic mirrors 9 and 11, to homogenizing optics 12 which serves to create a uniformly rectangular white beam with a specific half-cone angle that is displayed on one or more light valves in the image processor Examples of homogenizing optics are groups of fly-eye lenses (also called light bars) Blue laser 5 in the wavelength range 440 - 470 nm and red laser 7 in the wavelength range 630 - 650 nm emit beams 5 'and 7' directed to the development of optics 13 via a dichroic mirror 9. The combined beams 5 'and 7' are directed to the homogenizing optics 12, for example via dichroic mirror 11 The output of the homogenizing optics 12 is a white beam 14 incident on an image processor including a TIR prism and Philips prism structure, 16 at example, which splits the white light into three primary colors such as red, green, and blue beams that each impinge on a light valve 18a, 18b, 18C such as a DMD. Reflected light from the DMDs that is modulated in accordance with an image such as a video is reformed by the TIR prism and Philips prism structure 16 to form the projection beam 19 directed by a projection lens 20.

Note that no additional sharp filter is shown in or near the image processor in Figures 5 and 6, since it is one of the objectives of embodiments of this invention to minimize losses by avoiding the presence of a sharp filter in case of DCI compatibility. However, a sharp filter can be used in some embodiments, although this is less preferred.

However, in the case of requirements of even a wider color gamut, the additional sharp filter can still be introduced, for example at the entrance of the TIR and Philips prism structure, but again with lower filter losses than for a prior art case.

The first step that can be used with any of the embodiments of the present invention as shown in Figures 5 and 6 is to use a phosphorescent substance with a specific spectrum, other than the so-called gel phosphorus spectrum, such as from a YAG: Ce phosphor , in combination with direct blue lasers and direct red lasers in order to minimize light losses. The spectral power distribution of the light emitted by the phosphorescent under 440 - 470 nm excitation of the blue laser 2 of Figs. 5 or 6, has a peak wavelength shifted to lower wavelengths compared to what is commonly called "yellow phosphorescent" and that relative to the prior art, since its peak wavelength has shifted to lower wavelengths, this type of phosphorescent material will be referred to as a "green phosphorescent material."

A suitable "green phosphorescent agent" for reducing or minimizing losses in embodiments of the present invention such as an illumination system as described above with respect to Figures 5 or 6, must achieve the following conditions with respect to the spectrum: • Center of gravity wavelength <560 nm • Green content> 65% • GRTZC <16%

The first waveband can - optionally - be wider than the waveband of any individual laser source. In addition, embodiments of the present invention allow the addition of bluish light from a wavelength conversion element, such as a phosphorescent substance or quantum dots, that allows a wider waveband. Such a waveband can for instance be 480-500 nm. A number of laser wavelengths can be combined when a series of lasers is used. Secondly, cyan phosphor light of 480-500 nm can be added.

Examples of suitable green phosphorescent substances that meet the requirements described above include:

LuAG: Ce type of phosphorescent substances such as: the Lu3A15012: Ce from the article below: http://www.chemistryviews.org/details/ezine/7897011/The Future_of_Lighting.html • The GNYAG3557 from the Intematix portfolio http: // www .intematix. com / uploads / Phosphor% 20F amily% 20S hot / NY AGS ingleSheet. pdf

The second blue laser source can also be in the UV or near-UV wavelength ranges. This laser light is converted by the wavelength conversion element, so that the specific wavelength range of the excitation light is not so important. Blue lasers of 440 - 470 nm wavelength are currently an economical choice.

The red content is preferably <30% and optionally> 20%.

The percentage values refer to the relative energy contributions of the light converted by phosphorescent in a certain wavelength range compared to the entire phosphor light spectrum that is taken as 100%.

The green content is the part of the wavelength conversion element light spectrum, for example phosphor or quantum dots light spectrum before using the green waveband, hence this is preferably a considerable percentage such as> 65%. A larger amount means a higher light output at the end. The green waveband is optionally 495 - 575 nm as an example. This light is primarily intended to be modulated by the light valve in the green color channel. GRTZC is the "Green-Red-Transition Zone Content", which is light of a wavelength range with many losses occurring in the Philips prism and / or any additional sharp filter. This light does not belong very well to neither the green nor red waveband because it typically makes the colors unsaturated and the color gamut smaller. Embodiments of the present invention use a green wavelength conversion element, such as a green phosphorescent substance or green quantum dots in such a way that there is less amount of this type of light is then the yellow phosphorescent material of the prior art.

Red Content is the relative portion of the wavelength conversion element spectrum, such as a green phosphorescent substance or green quantum dots of the light entering the red waveband. The red waveband is usually operated by the direct red lasers, and it has it is preferable to add a quantity of reddish light from the wavelength conversion element such as a phosphorescent substance or quantum dots for the purpose of developing. An upper limit of this type of reddish light occurs when the color point moves from red to a too small color gamut, for example if the mainly orange light is around 600 nm, therefore, it is preferable that the red content is kept within such an upper limit.A suitable lower limit would be decomposition-related but may be of secondary importance when a red laser-decomposition process is used. 20% condition is optional, it should be noted that Blue Content + Green Content + RoodGe stop (“Blue Content + Green Content + Red Content”) is up to 100% for the wavelength conversion element such as a phosphorescent substance or quantum dots that are used.

Accordingly, the spectrum of the wavelength conversion element has light mainly in the green channel, and preferably only a small fraction goes to red and blue channels for limited color matching and laser development.

Moreover, especially when combining the beam in the illumination means is carried out using a system based on a dichroic mirror (as shown in the embodiments of Figures 5 and 6 above), it is also beneficial to add the following criterion: • Red content <30%

The parameters used to describe the green phosphorescent substance are defined as: • Center of gravity wavelength being the wavelength that divides the integral of a spectrum (where S (k) is the spectral energy distribution) into two equal parts according to the following formula:

• Green content is defined as

• Red content is defined as

• Blue content is defined as

• Green-red transition zone content (GRTZC) is defined as

In the above descriptions, S (X) represents the spectrum of the wavelength-converted light from the wavelength conversion elements such as phosphorescent material, which is integrated into the integrals above within the specified limits. Note that the spectral integration intervals as stated on the integral limit values are 575-600 nm for GRTZC.

The wavelength intervals used in the preceding formulas are based on typical values for half a wavelength for dichroic coatings in the Philips prism.

Peak wavelength is the wavelength at the maximum intensity of the spectrum. This is often used as a parameter in phosphor data sheets because it is very easy to determine from the spectral energy distribution. However, it has little meaning for practical purposes because two phosphorescent substances with exactly the same peak wavelength can have a completely different color perception. It is preferable to use center of gravity wavelength and blue, green and red content to more accurately describe the spectral characteristics of a phosphorescent substance.

A comparison between the optical spectrum of a typical green phosphorescent substance and a typical yellow phosphorescent substance used in embodiments of the present invention with 3-chip laser phosphor exposure system as shown in Figures 5 and 6 is shown in Figure 7.

The difference between the green phosphor spectrum and the gel phosphor spectrum does not have to be very large (for example a 19 nm shift in peak wavelength and center of gravity wavelength but this difference may be larger or smaller depending on the exact phosphorescent substances to be compared). However, this difference significantly affects the projector performance as will be described in detail below. Embodiments of the present invention can provide reduced brightness losses when a specific green phosphorescent substance is used in combination with direct blue lasers and direct red lasers.

The improvements appear at different levels in the projection design:

Fewer dichroic losses in the Philips prism or similar dichroic system used to separate the white light into the three primary colors.

A typical angle of difference (“Angle Of Incidence”, AOI) on the Philips prism coatings for incoming and outgoing light, which is used specifically in 3-chip DLP projection means, generates a "dip" around 490 - 500 nm (less visible in Figure 3) and more prominent around 575-600 nm (see Figure 3). The exact position and shape of the dip is of course dependent on the coating design and this can affect the final value of the brightness enhancement utilizing embodiments of the present invention, but the general conclusion remains the same.

The spectral characteristics of a typical yellow phosphorescent substance and a typical green phosphorescent substance in the 575-600 nm interval are shown in Figure 8, the interval being indicated by two vertical lines. These lines are also the preconditions in the integral above for the GRTZC. The green phosphorescent substance will perform better because it has a lower energy compared to the yellow spectrum in that specific wavelength interval. Therefore, the raised will be lower, especially since the Philips prism has a dip in the area shown by the two vertical lines shown in Figure 8 and the green phosphorescent material is shifted to lower wavelengths of that specific wavelength band.

This finding becomes even clearer if the optical spectrum is evaluated at three different positions:

System 1): blue lasers + yellow phosphorescent substance + red lasers (see figure 9)

System 2): blue lasers + green phosphorescent substance + red lasers (embodiments of the present invention, see figure 10):

Position 1 - this is the phosphor spectrum without any filtering as recorded just after the wavelength conversion has taken place;

Position 2 - this is the spectrum after the color-beam combination dichroically in the exposure part where these performance and energy losses may vary slightly depending on the beam-combining method used in the design-dichroic-based or end-based as explained below.

Position 3 - measured after the projection lens and this shows the effect of the Phillips prism

By performing power and brightness measurements at different positions, a typical value can be obtained which expresses that on average a system that uses a yellow phosphorescent material is about 9% less clear than a system that uses a green phosphorescent material in accordance with embodiments of the present invention, due to dichroic losses in the primas alone.

Less losses due to the sharp filter

By measuring the color points of the primary colors for both systems 1) and 2), additional problems and sources of losses for the gel phosphorus systems are revealed.

System 2) that uses the green phosphorescent material plus direct blue and red lasers can be made very close to absolute DCI compatibility. First, regarding the color gamut made from primary colors by applying the exposure to the Philips prism with suitable coatings, and without using any additional sharp filter. Secondly, with regard to the white point, by using the appropriate power levels of the three types of laser sources as shown in Figures 5 and 6, without any use - or only minimal use - of color correction via the image formers.

Comparison system 1) that uses the yellow phosphorescent material is not DCI compatible, especially with regard to the green primary color. A sharp filter will be needed to bring the color points of some of the primary colors such as primarily the green primary color into the relevant DCI tolerance boxes. DCI tolerance boxes indicate variations for, for example, the primary colors, so that they are still "within specifications". With the gel phosphorus solution of the prior art and no sharp filter applied, the green primary color typically falls outside the green tolerance box. This is shown in Figures 11 and 12.

And as mentioned earlier, such an additional sharp filter, as needed in a yellow spectrum configuration, is typically responsible for an additional 18% decrease in brightness.

Less losses in a dichroic system to combine the direct red lasers with the red light of the phosphorescent material

In a red assisted laser phosphor light source, additional red lasers or red LEDs are used to improve the red-to-white ratio and to widen the primary color red in the achievable color gamut.

Various methods for combining red light from the red lasers with the red component of the yellow phosphorescent can be used: etendue and wavelength-based systems are the most common. Polarization-based combination is also possible, but this requires special measures of the optical design and this is less common. The same methods can be used with embodiments of the present invention that use the green phosphorescent substance.

When the wavelength-based recombination method is used, part of the light from the phosphorescent is used because it has the same wavelength as the direct lasers.

In Figure 13, an example is the case of a single wavelength of 635 nm.

Less light needs to be filtered in the case of the green phosphorescent material (embodiments of the present invention) to make room for the addition of direct red lasers. For the case of the two different ("yellow" and "green") phosphorescent materials used in these calculations, the yield in brightness is again about 9% in favor of the green phosphorescent substance used in embodiments of the present invention invention.

In the case of the wavelength combination for red lasers - red light from the phosphorescent, it is preferable to add additional limitation to the spectral characteristic of the green phosphorescent in the sense that the Red content is preferably lower than 30%.

Improvements through higher efficiency of the green phosphorescent substance

Theoretically, a green phosphorescent substance will have a higher conversion efficiency due to a lower Stokes shift when compared to a yellow phosphorescent substance. This means that the same level of excitation by blue lasers on green or yellow phosphorescent materials will create a higher energy level of converted light in the case of the green phosphorescent substance, which is then also used more in the green channel (higher green content), and less wasted in the green-red transition filtering that takes place in the imaging processor (points 1 and 2 above), and less loss in the red channel when the additional red laser light is added via a dichroic (wavelength-based) method (point 3 above).

All three types of improvements described above put together, the embodiments of this invention using a green phosphorescent generated by blue lasers, with additional blue lasers and red lasers, will be approximately 32% more efficient in using the phosphor light than the same system that uses a yellow phosphorescent substance as shown in Table 1:

Total 32%

Losses due to the dichroic being used 9% to make room for the red laser addition

Losses due to the sharp filter: 18%

Losses in the prism: 9%

Table 1

Embodiments with additional improvements

In the first embodiments of the present invention, the characteristics of the green phosphorescent material make it possible to reduce or minimize losses in a red-assisted configuration. For the second step of the invention, embodiments with additional limitations are described that may bring additional improvements: 1. Minimum blue content> 1.5%

If 445 or 455 nm lasers are used for the direct blue laser path instead of the more expensive 465 nm lasers, it is advantageous for a small portion of the phosphor light to leak into the blue channel. The blue primary color obtained with direct 445-455 nm lasers is not DCI compatible. However, adding cyan light for the phosphorescent in the right amount will bring the blue color point into the DCI tolerance box. This is achieved in the system that uses the described green phosphorescent substance. Typically, less cyan light is available with yellow phosphorescent agents when the spectrum is shifted to higher wavelengths as shown in Figure 13. 2. Minimum red content> 20%

In the first embodiments of the present invention described above, when the wavelength combination is used to add the direct red lasers to the red light of the green, it is advantageous to have a small red content (e.g., less than 30%). to have. However, it is preferable for the purpose of decomposition to have as much red contribution as possible of the phosphorescent material, since this provides a completely spot-free contribution. Therefore, in embodiments of the present invention, the minimum red content target is set to 20%. That is why a preferred range is 20-30%.

Embodiments of the present invention provide a 3-chip projector architecture that utilizes phosphor light from a green phosphorescent material (e.g., with specific spectral properties) and combines it with additional blue and red laser light such that the projector has a higher light output efficiency in the case of wider color gamut applications such as DCI.

For adding the red laser light and the fraction of phosphor light going to the imager in the red channel of the imaging module, there are two conceptually different methods. - Dichroic-based combination - Bundle-étendue-based combination.

The dichroic-based combination method, when used in the embodiments shown in Figures 5 and 6, typically uses a dichroic mirror to combine the laser light and the phosphor light. This means, for example, as seen on mirror 11 in Figures 5 and 6, that the red laser light, which typically has a larger wavelength, is transmitted to the imaging processor, and the lower wavelengths of the phosphor light are reflected to the imaging processor.

This combination method involves some losses in the transition wavelengths, and due to the higher contribution of the small band laser wavelength, it is preferable to place the transition wavelength range (between reflection and transmission of the light) slightly lower than the laser wavelength, with a result that the higher wavelength contributions of the phosphor light are lost. See figure 15.

The bundle-edendue-based method is known from US2013 / 0100644, see figure 16. US2013 / 0100644 is incorporated in its entirety by reference. US2013 / 0100644 describes an excitation light source, an additional light source, a light combination device, a light collecting device, a light reflection device, a wavelength conversion device, a reflection substrate and a light homogenization device. The excitation light and the additional light are combined by the light combining device, then the combined light is incident on the light collecting device. After being collected and transmitted by the light collecting device, the combined light falls on the wavelength conversion device. The wavelength conversion device absorbs the incident excitation light and converts it to a converted light whose wavelength differs from that of the excitation light. The converted light generated by the wavelength conversion device is isotropic, so that part of the converted light will propagate in the opposite direction of the excitation light while another part of the converted light will propagate in the forward direction. Meanwhile, a portion of the excitation light transmitted by the wavelength conversion device will be reflected by the reflection substrate located on the side of the wavelength conversion device away from the excitation light source. The incident incident light is further scattered by the wavelength conversion device. Part of the scattered additional light is reflected directly by the wavelength converter and propagates to the light reflection device, while another part of the scattered additional light passes through the wavelength conversion device and is reflected by the reflection substrate back to the wavelength conversion device and passes through it. The majority of the converted light and the majority of the additional light are collected and directed to the light homogenization device for homogenization.

In this case, the light-collecting optics are made that capture the reflected light that has been converted by the phosphorescent material from a first laser source that excites the phosphorescent material, and that it reflects the additional laser source of a different color. There are no losses from the wavelength perspective. The spectrum of the red laser will be laid over the spectrum of the phosphor light, with no transition zone and spectral dip for wavelengths that are slightly smaller than the red laser wavelength.

In this case, however, there will still be a few geometric-based losses from the reflected laser light that can come back to the access aperture in this system, even when the additional idea of a reflective filter for the phosphor light is added as described in US2013 / 0194551. The bundle-edendue-based combination system suffers from the geometric losses created by the access aperture in the collection optics, and is, therefore, generally less efficient for this function.

The idea of using the green phosphorescent substance with its specific spectral characteristics will not be influenced by this combination process, with regard to the following aspects: - The amount of yellow light lost in the Philips prism and / or additional sharp focus. - The lower dominant wavelength of the light entering the green channel of the 3-chip imager. - The amount of cyan light from the green phosphorescent material.

Use of a green phosphorescent substance instead of a yellow phosphorescent substance is advantageous for the case where the dichroic-based combination method is used, and where the amount of the phosphorus-converted light loss will be lower in the case of the green phosphorescent substance instead of the yellow phosphorescent substance dust.

As will be further described in a second embodiment, the embodiments of the present invention are not limited to a green phosphorescent substance.

Second embodiment

According to a second embodiment of the present invention, the wavelength conversion element 8 shown in Figure 5 or Figure 6 may be a yellow phosphorescent material, in which case the light emitted by the conversion element has a spectrum similar to state-of-the-art projectors, such as those illustrated in Figure 3.

The yellow phosphorescent material is responsible for generating the primary red and green, but with an excess of green and intermediate wavelengths that lie between the primary green and red, leading to the unsaturation of primary colors as previously described. However, an important difference from prior art projectors relates to the use of two independent lasers to generate the blue primary color and to excite the wavelength conversion element, thereby reducing the number of degrees of freedom for controlling the white point of the projector increases.

Because the red primary color is provided by the wavelength conversion element, the red laser becomes optional. It can be used to increase the red contribution or it can be removed in which case the red primary color will only be provided by means of the wavelength conversion element.

Assuming that the red laser is not used, in this second embodiment of the present invention, the excess of the green waveband cannot be reduced independently of the red waveband. It is thereby desirable to provide further means to reduce the contribution of the green waveband independently of the red waveband. Such means can be provided by a variable green waveband reduction filter.

Reducing the contribution of any waveband responsible for generating a primary color, the contribution of which is in excess before entering the corresponding light modulator, has the advantage of reducing the heating, and thereby the losses generated by the light modulator but also to improve the contrast ratio and the bit depth of the primary color corresponding to the light modulator.

However, such means are not incompatible with the use of the red laser, since the variable waveband reduction filter provides additional degrees of freedom for controlling the white point.

Blue laser 3 and blue laser 5 can emit light in a waveband of [380,495] nm. Note that in the direction of the shorter wavelengths of the range, the human eye sees the blue as violet. If the blue laser 5 produces light that is used for the blue primary color (or the blue waveband of the imaging module), this light source determines the visual perception of "blue images", in practice only a small waveband interval is suitable, around 465 nm , such as laser wavelengths from 450 to 470 nm. Below 450nm, the blue becomes very violet.

The blue laser 5 is intended for the excitation of the wavelength conversion element. Theoretically, this excitation can be induced by any wavelength that the phosphorescent substance excites (as given by the phosphorus absorption spectrum), that is, said 380 to 495 nm interval. Those skilled in the art will understand, however, that lasers for exciting the phosphorescent are not limited to the waveband corresponding to blue light, and lasers with a wavelength lower than 380 rmj, i.e. UV lasers, are also suitable for exciting the phosphorescent substance.

In preferred embodiments, each light source has a full width at a half maximum (FWHM) of about 5 nm.

For example, the laser 5 can emit a light beam 5 'with a central wavelength of 465 nm, with a wavelength of +/- 5 nm, and the laser 3 can emit a light beam with a central wavelength of 445 nm, with a waveband of + / - 5 nm.

Each laser source can comprise a series of lasers. In an embodiment of the present invention, the laser 5 comprises a series of 16 lasers and the laser 3 comprises a series of 48 lasers. Each laser can be a laser diode. Laser arrays usually use a single laser diode type and provide multiple laser beams.

The wavelength conversion element 8, after absorption of a light beam at an excitation wavelength, emits a light beam, by emission or reflection, the wavelength band of which is changed with respect to the wavelength of the absorbed light beam.

Wavelength conversion element 8 can be a phosphorescent material which, after absorption of the blue beam 2 ', emits a converted beam which, due to the phosphor emission, comprises green, yellow and red light. The phosphorescent material has converted the blue emission of the second light beam centered at the 445 nm wavelength to light emitted in the 500 nm to 700 nm waveband with a peak around 570 nm, so that it serves to generate green at the same time light and red light. However, the spectrum also shows a shortage of red light and an excess of green light and yellow light.

The excess of yellow light can be removed by means of a sharp filter, such as prior art projectors. The yellow sharp filter can attenuate the light in the narrow wave band of 570-600 nm, preferably with a transmission that is as low as possible, for example around 10-15%. For the user, the use of this filter results in a green that appears as being less yellowish and a red that appears as being less orange, and therefore as an original white point with less yellow.

However, a light beam that excites the yellow sharp filter 370 still shows an excess of green light.

To compensate for the aging of lasers and / or the aging of the wavelength conversion element 8, and with the advantage of further reducing the amount of blue and / or green light inherent in the laser phosphor system described in the present embodiment, it is an advantage of the present invention to provide means to adjust the relative contribution of each waveband to generate original primary colors that match the primary colors as far as possible. As a result, any original primary color supplied to the imaging module matches the desired group of color coordinates as determined, for example, in the DCI system, and thus matches the target white point without loss of contrast or bit depth, even when the lasers or other optical components are aging.

Embodiments of the present invention provide solutions to the above problems. According to embodiments of the present invention, the green wave band reduction filter comprises a variable green wave band reduction filter so as to adjust the amount of green light emitted by the filter. It is an advantage that the reduction of the green light contributes to the primary green color upstream of the imaging module, impedes the reduction of green light through the associated DMD, keeping the range of movement of the DMDs to its maximum, and thereby the bit depth associated with the color channel is retained.

FIG. 19a-19e illustrate various embodiments of a variable green waveband reduction filter according to embodiments of the present invention.

The embodiment of FIG. 19a includes a green filter coating comprising a cartridge on one side of the filter with an increased density of green reducing cartridges.

In preferred embodiments, the green light reduction filter comprises an actuator, such that the amount of green light emitted by the filter can be adjusted by moving the position of the fdter. The actuator can be a rotation platform for rotating the tunable filter or at least one translation platform for moving the tunable filter in a direction perpendicular to the optical axis. The coating pattern advantageously comprises a pattern with an increased density of green-reducing patterns, wherein the direction density increase is adjusted to the direction of movement of the mechanical actuator such that the intensity of the green spectral band can be adjusted. In preferred embodiments, the actuator can be controlled by a controller.

Preferred embodiments of the present invention combine the variable green reduction filter with the yellow sharp filter. An example of such a filter comprises the green pattern coating on one side, and the coating of the yellow sharp filter on the other side. Consequently, the projection system can only limit the yellow light to enter the imaging module or to further adjust the amount of green light, as a function of the performance of the system (aging of the lasers, phosphor, wavelength conversion element 8) and the desired optical output.

Other embodiments of variable green waveband reduction filters are illustrated in FIG. 19b - 19th. Figure 19b shows a filter with a rectangular continuous green reduction coating that provides linear, adjustable attenuation within the coated area via translation; 19c shows a filter with a rectangular reduction in step coating that provides adjustable attenuation in steps that are within the coated area via translation, FIG. 19d shows a round filter that provides linear, adjustable attenuation within the coated area via rotation and FIG. 19e shows a round filter that provides linear attenuation in steps within the coated area via rotation of the filter. The filters shown in FIG. 19 can be advantageously combined with the yellow sharp filter to reduce the amount of optical elements in the projection system.

FIG. 20 shows the effect of a displacement of a variable green waveband reduction filter according to embodiments of the present invention on the broadcast provided by the filter.

Other embodiments may include a filter wheel with a plurality of green wave band reduction filters, each with a different broadcast, such as 8 filters with broadcasts of 20, 30, 40, 50, 60, 70, 80, 90% for the green wave band, respectively. The green wave band sharp filter can be coupled to the yellow sharp filter, as discussed above. The variable green wave band sharp filter can reduce wave regions in the range 510-570 nm, and where the reduction factor is as constant as possible over this spectral range.

A consequence of the new fdter characteristic of the present invention, which comprises a combination of the yellow sharp filter and the green wave band intensity reduction filter, is a reduction of the green excess light in the illumination that goes to the imaging module 380, making it possible to achieve final contrast, bit depth, and target point can be improved.

A variable wave band sharp filter as shown in Figure 19 can be adapted to any wave band that requires upstream dimming of the DMDs. In particular, a variable red or blue wave band reduction filter can be implemented in the optical path of the white beam or to further reduce the reddish and bluish light of the wavelength conversion element. In these embodiments, the variable blue and red reduction filter are similar to the variable green reduction filter shown in Figs. 19 a - e. The variable blue reduction filter can reduce the intensity of wavelengths in the blue wavelength range and the variable red reduction filter can reduce the intensity of wavelengths in the red wavelength range, and where the reduction factor over this spectral range is as constant as possible. Like the variable green reduction filter, the actuator is preferably driven by a controller.

Sensor

Embodiments of the present invention may use an external multi-band sensor or an integrated sensor. An external sensor detects an illumination level that is emitted from the projection lens. An external or internal sensor detects an illumination level of the imaging portion of the projector or light emitted from the projection lens, respectively, and the sensor values are fed back to a control and / or directly to a controller processing unit. A new control level is selected for controlling the lighting component (s) in accordance with the sensed values so that the light level is controlled, i.e. a higher control level so that the light output loss is compensated, as described in US2011 / 304659 for lamp-based projectors.

In the case of an illumination system according to embodiments of the present invention, a color sensor can be added which makes it possible to control the light level, while maintaining the white point and the color points. For this, the color sensor is preferably equipped with multi-band detection options. An embodiment of the present invention and an example of the location of a multi-band sensor, and an example of the sensitivity ranges of the multi-band sensor are described with reference to Figures 17 and 18. Figure 17 shows the addition of a sensor 22 and controller 24 that provide feedback control. from the controls 2, 4, 6, and where applicable to the actuator control of a variable waveband reduction filter (not shown) to the embodiment shown in Figure 5. The same sensor 22 and controller 24 can be exactly the same way added to the embodiment shown in Figure 6 and being included as an embodiment of the present invention.

The light sensor or sensors can be at least one of a photodiode sensor, light sensitive resistor, organic photoreceptor, spectrometers, photo amplifiers, CCD or CMOS sensors.

The controller 24 takes the feedback from the multi-band detection of the color sensor 22, and derives therefrom the appropriate control levels for the controllers 2, 4, 6 and the different laser sources 3, 5, 7, and the control of the variable waveband reduction filter, if applicable , so that the desired brightness level is achieved for the projector at a certain desired (and stable) white point. And on a second level this approach can also be used to correct for any differences from the individual primary color points of the projector, for example - to give an example - to compensate for a changing ratio of red laser light and red light from the phosphorescent substance that would affect the color point of the red primary color that is composed of the two contributions.

The present invention provides an independent invention of a multi-band color sensor for controlling combinations of phosphor light and laser light. This independent invention provides a controller that takes the feedback from multi-band detection of a color sensor or color sensors, and derives therefrom the appropriate control levels for at least one control of one or more laser sources, and when applicable, the correct control level of a variable waveband reduction filter such that a desired brightness level is achieved at a certain desired (and stable) white point. This embodiment can be used to correct differences of individual primary color points, for example to compensate for a changing ratio of red laser light and red light of a phosphorescent material that would affect the color point of the red primary color composed of two red contributors. This embodiment may also include a controller processing unit configured to communicate with a multiband optical control unit adapted to measure the relative intensity of first, second, and third wavelength bands of a white beam, the processing unit of the controller further calculates a change in the control levels of the first to third laser beam and the control positions of the variable waveband reduction filter when applicable according to the relative intensity of the first, second and third wavebands of the white beam to adjust a white point shift, and wherein the first until third laser controls are independently controlled so as to adjust the light intensity of each of a first and second blue laser source independently of the light intensity of a redundant source.

In other embodiments, the multi-band sensors may be placed on the screen and periodically measure a small area of any of the projected image (e.g., on the projection screen of a movie theater).

In embodiments of the present invention, the multiband sensor can be embedded in the projector system, a variable blue and red reduction filter can be used to further reduce the reddish and thereby periodically calibrate the primary color control means. Periodic can be systematic at start-up or shutdown, during projection, during periodic calibrations of the system, for example prior to each projection or monthly etc. Calibration can also be performed for a projection with a predefined test pattern. The multi-band sensor can preferably receive light from the light beam through a foldable mirror placed in the optical path. The foldable mirror is adapted to receive, for example, 0.5% of the light beam. Hence, 99.5% of the light continues to be sent to the imaging module. The light loss is negligible compared to the yield provided. The system can be adjusted to move the foldable mirror and the light beam.

Laser versions

In the embodiments of the present invention described herein, light sources 320, 330 are advantageously laser light sources, which comprise a series of lasers. An advantage provided by laser light sources is that a laser provides a collimated light beam with a small etendue. However, the invention is not limited to laser light sources, and may also include LED light sources or superluminescent diodes.

For laser sources that provide direct illumination for a certain waveband of light in the imaging module, without any wavelength conversion element (i.e., specific wavelength ranges) going into the red and blue channels, for better color matching.

In these embodiments, the blue and red reduction filter includes an actuator such that the amount of blue and red light transmitted through the filter can be adjusted by moving the position of the filter. The actuator can be a rotation platform for rotating the tunable filter or at least one translation platform for moving the tunable filter in a direction perpendicular to the optical axis of the projector system. The filter can include a coating pattern. The pattern may have an increased density of blue and red-reducing patterns, the direction of density increase being adapted to the direction of movement of the mechanical actuator such that the intensity of blue and red light in the optical path can be adjusted, it may be beneficial to add a stimulant to reduce speckles in the final image on the screen (in that primary color). Such decay techniques can include polarization diversity, wavelength diversity, spatial and angular diversity, the benefits of which provide a reduction of speckles in the projected image.

Because the multiband sensor preferably measures at least the relative intensity of the wavebands according to the primary colors of the projection system, a full spectral measurement may be useful when major changes in the spectrum occur, since such changes can have a major impact on the white point, even regardless of a change in gloss or overall intensity of the bundle. In such special cases, a recalibration of the system with a spectrograph may be beneficial for a white point reset.

The different laser controls and variable waveband reduction controls provide new degrees of freedom within the color space, and therefore, wider color ranges within the color space can be provided by the primary color control means described in the present patent application. Because there is now a tendency to move to a wider color gamut for other applications (in the extreme the Rec2020 range), the described invention may also have an application for such Wide Color Gamut ("Wide Color Gamut") activities on a more generic mode than DCI.

There is a need to calibrate three or more projectors for use at the same time, such as in accordance with the Barco Escape ™ film platform. According to embodiments of the present invention, a processing unit can be connected to the three or more projectors via a cable (e.g. USB) or through a wireless connection. The processing unit is preferably connected to a control unit that is itself connected to a multi-band sensor for each projector. The control unit and / or the processing unit can be integrated into a projector or can be an independent device. Thus, three or more (N) projectors can be provided with a control unit within each projector and a multi-band sensor placed in front of the projection lens or integrated in the projector.

The processor can initiate a series of test images and record the results of sensors placed in front of the projector lens. For internal sensors, test patterns are not required, the sensors being placed in the illumination beam, and it is preferable to work with "relative values", that is, with differences between factory-set values (only an initial calibration in the factory with an external color meter is required) and the real values instead of working with absolute values. The initial measurement results for the sensors are used in the factory alignment with the target color performance on the screen, and these initial measurement results can be stored in a projector, a local processor device such as a laptop or remotely.

A variable waveband reduction filter can be placed in the optical path to reduce light respectively in the waveband of the blue imager and in the waveband of the red imager, without affecting the respective laser wear. In this way the color points of blue and red can be matched between the laser point and the color point of the mix of laser light and light from the wavelength converting agent such as, for example, phosphor light.

Although an electronic correction system has been developed to electronically adjust primary colors and white point, with embodiments of the present invention, electronic correction is avoided or reduced. This can be done by color matching, for example, with methods and compositions with a green phosphorescent substance. White color balance can be manually adjusted on the processing unit by controlling laser drivers and adjustable intensity filters, if any, as well as a variable or movable waveband reduction filter. This is a significant improvement over prior art devices.

Color gamut data, color coordinates and relative luminance values can be obtained by this checking method and can be stored in the projectors themselves in the processing unit or elsewhere such as on a server in a LAN or WAN network such as the Internet. Such values can be measured in the factory using test patterns and good color meters, and stored in the projectors.

For alignment in a field installation, the desired common color gamut and white point can be set by looking at the data. An application can be run on a computer, PDA, smartphone, etc., which reads the stored gamma values, optionally via a network connection, and the best registered gamma and the best written white point are found. Or a data connection can be between the projectors and a server via the network where the calculations are performed in the server. This can be advantageous because such a server can have powerful microprocessors. The stored data can be updated to take account of aging effects using the multi-band sensors and test patterns can be reused.

A processor with a processor device such as one or more microprocessors within the projector, located locally on the projector or remotely, can automatically perform the above alignment procedure. This can be achieved through communication between a number of projectors, exchange of sensor values and setting status, which may become necessary if, for example, one of the settings is no longer feasible. For example, if necessary, a reduction of the objectives could be implemented.

A similar calibration procedure can be made when multiple projectors are used when overlapping the projected images on connection positions. Electronic mixing can be used in the overlapping zone. However, if the projectors emit different colors, the mixed areas may become visible. This can be disturbing for planetariums, simulators or other Virtual Reality applications. For simulation, which is used for training, for example, there are different types of multi-channel systems that can utilize embodiments of the present invention, such as versatile displays, collimated displays, reality centers, CAVEs, etc. The latest multi-projector applications do not have to be a cinema standard such as DCI, so that the color gamut size may be less relevant than color matching.

Barco Escapeta is a multi-projector set-up for cinemas, for example with a center screen and two side screens. For the best performance and acceptance, the projectors should meet the Digital Cinema specifications, for example with regard to the DCI color range. The embodiments that use a green wavelength conversion element such as a green phosphorescent substance are efficient for the DCI or other similar wide color gamut.

The images are located on different three shanks at different angles, so it is assumed that the main disturbance of the coupling between the images would be the different color point, more than if there were any variation in brightness. The embodiments of the present invention can be applied to Escape ™ in that the three-color projector system can be color-matched with DCI color gamut compatibility.

For a projector with a green wavelength conversion element according to embodiments of the present invention and without the addition of a variable waveband reduction filter, three different adjustment settings Si per projector of N projectors: the direct blue laser power level, the blue laser power level for excitation of the wavelength conversion element, such as a phosphorescent dust, and the power level of the red lasers. For the multiple projectors, all sy setting 1 settings and projector j are set so that all projected white points are set to the common white point that is the DCI target point. For example, assuming the projectors are aged in different ways, the intensity ratios of the intensity if they are outdated to an initial value Iaged / Iinit should be made equal for all sub-wave bands of all projectors, with an overall maximum target value for this ratio is taken so that none of the settings s, 0 of each of the projectors go beyond the maximum value for that setting (that is, only equal or lower is used).

Another way a DCI-compatible system works is to only aim for a certain light output that is lower than the maximum possible through the projector, for example, to strictly adhere to the DCI luminance spec on the screen. In that case it will be necessary for the settings Si to be adjusted until that initial lighting level is also reached. The white point can also be adjusted partly via the lighting level and the si settings, and partly via electronic correction. A low or lower amount of electronic correction can only be tolerated for some applications.

For embodiments with a waveband reduction filter, the same sy settings can be adjusted to fix the projectors to the white point (without electronic correction). As such, insofar as the laser contribution versus the contribution of the wavelength conversion element such as a phosphorescent material has become different in both red and blue, the additional capacity to control and adjust the waveband reduction filters can be used to also contribute the phosphor tail contributions so that the color gamut can be larger again, while for the white this can be compensated by again increasing the laser contribution. 3D projection can be achieved using embodiments of the present invention. First, red lasers and blue lasers of different and non-overlapping wavelengths can be used for the left and right eye. In an optical channel, such as the right eye channel, green Quantum dots can be used and for the other eye a yellow Quantum dots, each of which is excited by laser light. The viewing glasses are equipped with a filter that would filter between left and right eye optical signals emitted by the projector.

Alternatively, a projector can include red and blue laser with different wavelengths for the left and right eye. The light from the yellow or green wavelength conversion element, such as phosphorescent material, can be polarized in different directions. The viewer wears a bnl which filters the relevant right eye or left eye wavelengths and in the case of green colors, the bnl has the correct polarity to receive the modulated green light.

Claims (54)

Adapted conclusions for BE2016 / 5090 A light projection system for generating an image with three primary colors, being blue, green, and red, each primary color being defined by a first, second, and third waveband respectively, the light projection system comprising: a first blue laser source that emits a first beam in a fourth waveband, the first blue laser source having a first laser control, - a second blue laser source emitting a second beam with a central wavelength and a fifth waveband, the second blue laser source having a second laser control, a substrate with a wavelength conversion element for emitting light at a plurality of wavelengths after absorption of a light beam at an excitation wavelength within the fifth waveband of the second blue laser source, the substrate being positioned in an optical path of the second beam such that light transmitted by the wavelength conversion element or be reflected by it dt, results in emission of a converted bundle with a waveband comprising at least the second and third wavebands, and - a bundle combining means for combining the first bundle and the converted bundle, characterized in that the combination results in a white bundle; and the projection system further comprises an optical control unit for measuring the relative intensity of the first, second and third wavebands of the white beam. The light projection system of claim 1, wherein the optical control unit comprises at least one light sensor. The light projection system of claim 2, wherein the at least one light sensor is a multi-band sensor configured to measure the intensity of wavelengths included in the first, second, and third wavebands. The light projection system according to claim 3, wherein the multi-band sensor is configured to detect any difference in the light spectrum between a laser light and a converted beam. The light projection system according to any of claims 2-4, wherein the optical control unit receives light through a foldable mirror placed in the optical path of the white beam such that about 0.5% of the light is reflected to the at least one light sensor. A light projection system according to any of claims 2-5, wherein the at least one light sensor is at least one of a photodiode sensor, photoresistance, organic photoreceptor, spectrometer, photo amplifiers, CCD or CMOS sensors. The light projection system according to any of the preceding claims, wherein the projection system further comprises a processing unit configured to communicate with the optical control unit. A light projection system according to claim 7, which is adapted to feed back sensor values from at least one sensor to the optical control unit and / or directly to the processing unit to determine a new control level for control sources in accordance with the sensor values so that the light level is controlled is becoming. The light projection system of any one of claims 5-8, wherein the foldable mirror is configured to be retracted in and out of the white bundle. The light projection system of claim 9, wherein the foldable mirror is mounted on an actuator controlled by the processing unit. A light projection system according to any of the preceding claims, wherein the wavelength conversion element emits converted light at: - a center of gravity wavelength <560 nm - a GRTZC <16%. The light projection system of claim 11 wherein the green content is defined as a part of the light spectrum of the light emitted from the wavelength conversion element going into the green waveband, the green waveband being in the range 495-575nm, and a "Green Red Transition Zone Content (GRTZC), defined as A light projection system according to claim 11 or 12, wherein the wavelength conversion element emits light with a green content> 65%. A light projection system according to claim 12 or 13, wherein the green content is <75%, optionally <80%. The light projection system according to any of the preceding claims, further comprising a third red laser source that emits a third beam in the third waveband, the third red laser source having a third laser control. A light projection system according to any preceding claim, which is implemented as a 3-chip projector architecture. A light projection system according to any preceding claim, wherein the first or third waveband is wider than the waveband of any individual laser source. A light projection system according to any preceding claim, which adds bluish light from the wavelength conversion element in the wavelength 480-500 nm. The light projection system according to any preceding claim, wherein the first or second blue laser in the waveband is 400-495 nm 440-470 nm wavelength. A light projection system according to any preceding claim, wherein a red content is preferably <30% and optionally> 20%, the percentage values referring to relative energy contributions of the converted light from the wavelength conversion element in a given wavelength range compared to the entire light spectrum of the wavelength conversion element that is taken as 100%. A light projection system according to any preceding claim, wherein the green waveband is in the range 495 - 575 nm. The light projection system according to any of claims 11 to 21, wherein the GRTZC refers to light that makes colors unsaturated and makes the color gamut smaller. A light projection system according to any preceding claim, wherein a red content in a light beam is the relative portion of the wavelength conversion element spectrum going into the red waveband. The light projection system of any one of claims 14 to 23, wherein the red waveband has light from the red laser, and an added amount of reddish light from the wavelength conversion element for development. The light projection system of claim 24, wherein an upper limit of the reddish light is achieved when the color point moves from red to a smaller color gamut. The light projection system of claim 24 or 25, wherein the reddish light is orange light in the range of 595 - 620 nm. A light projection system according to any preceding claim, wherein the Blue light + Green light + Red light is up to 100% of the light of the wavelength conversion element. A light projection system according to any of the preceding claims, further comprising a sharpness that reduces light intensity of wavelengths in the wavelength 570 - 600 nm. The light projection system of claim 28, wherein the sharp filter reduces light intensity in the range of 10 - 15% or 10 - 20%. A light projection system according to any of the preceding claims, further comprising at least one variable waveband reduction filter mounted on an actuator and provided in the optical path of the white beam, and wherein a movement of the variable waveband reduction filter between a first and a second position results in a change of the transmitted waveband of the white beam from a first to a second transmitted intensity, so as to adjust a projector white point. The light projection system of claim 30, wherein the variable waveband reduction filter is a first waveband reduction filter, a second waveband reduction filter or a third waveband reduction filter, such that it is configured to change the intensity of wavelengths included in the first, second, or third wave bands, respectively. The light projection system of claim 31, wherein the sharp filter and the variable waveband reduction filter are combined in one and the same variable filter. The light projection system of claim 32, wherein a first side of the variable filter is coated with a narrow band sharp filter and a second side of the filter is coated with a variable wave band reduction filter. The light projection system of any one of claims 31 to 33, wherein the variable second waveband reduction filter is configured to reduce the intensity of wavelengths comprised in the range of 510-570 nm. The light projection system of any one of claims 30 to 34, wherein the actuator is controlled by the processing unit. The light projection system of claim 35, wherein the actuator comprises a rotation platform for rotating the variable second waveband reduction filter about the optical axis or at least one translation platform for moving the variable second waveband reduction filter (371) in a direction perpendicular to the optical axis. A light projection system according to any of claims 31-36, wherein the variable second waveband reduction filter comprises a lining provided with a pattern with an increased density of green-reducing patterns, the direction of density increase being adapted to the direction of movement of the actuator that the intensity of the second green spectral band can be adjusted. The light projection system of claim 37, wherein the variable second waveband reduction filter comprises at least one of a rectangular continuous green reduction coating that provides a linear, controllable decrease within the coated area via translation, a filter with a rectangular stepwise reduction coating that includes a step-controllable decrease within the coated area via translation, a round filter that provides linear, controllable decrease within the coated area via rotation, or a round filter that provides linear decrease in steps within the coated area via rotation of the filter. A light projection system according to any of the preceding claims, wherein the wavelength conversion element is a phosphor. The light projection system of claim 39, wherein the phosphor is of the YAG: Ce type. 4L Light projection system according to claim 39, wherein the phosphor is of the LU type AG: Ce. The light projection system of any one of claims 1-38, wherein the wavelength conversion element comprises quantum dots. The light projection system of any one of claims 7 to 42, wherein the processing unit is configured to communicate with the optical control unit for measuring the relative intensity of first, second and third wavelength bands of a white beam, the processing unit is further configured to calculate a change in the control levels of at least one of the first to third laser beams and the control levels of the at least one variable waveband reduction filter according to the relative intensity of the first, second and third wavebands of the white beam around a control white point shift, and wherein the first to third laser controls are independently controlled so as to adjust the light intensity of each of a first and second blue laser source independently of the light intensity of a red laser source. A light projection system according to any preceding claim, wherein the optical control unit is adapted to control different contributions in any, some or all of the wavebands. A light projection system according to any preceding claim, wherein the optical control unit is arranged to monitor both the laser light and the wavelength conversion element light contribution in the blue waveband. A light projection system according to any preceding claim, further comprising a variable blue and red reduction filter. The light projection system of claim 46, wherein the variable blue and red reduction filter further reduces the reddish and bluish light of the wavelength conversion element going into the red and blue channel. A light projection system according to claim 46 or 47, wherein the blue and red reduction filter can include an actuator such that the amount of blue and red light transmitted through the filter can be adjusted by moving the position of the filter. A light projection system according to any of the preceding claims, wherein each laser source comprises a series of individual lasers, wherein the intensity of each individual laser is controlled by its laser control and wherein each laser is configured to be pulsed by its associated laser control. A light projection system according to any of the preceding claims, further comprising beam homogenization optics. A light projection system according to any of the preceding claims, further comprising a decomposition means. 52. Optical assembly for a light projection system for generating an image with three primary colors, being blue, green, and red, each primary color being defined by a first, second, and third waveband respectively, the optical assembly for use with a first blue laser source that emits a first beam in a fourth waveband, the first blue laser source having a first laser control, a second blue laser source emitting a second beam with a central wavelength and a fifth waveband, the second blue laser source having a second laser control, the assembly the following comprises: - a substrate with a wavelength conversion element for emitting light at a plurality of wavelengths after absorption of a light beam at an excitation wavelength within the fifth wavelength of the second blue laser source, the substrate being positioned in an optical path of the second beam such that light passes through the wavelength conversion element transmitted or reflected by it results in emission of a converted beam with a waveband comprising at least the second and third wavebands, and a beam combining means for combining the first beam and the converted beam, characterized in that the combination results in a white bundle; and the optical assembly further comprises an optical control unit for measuring the relative intensity of the first, second and third wavebands of the white beam. The optical assembly of claim 52, further comprising generating laser light from a third red laser source that emits a third beam from the third waveband, the third red laser source having a third laser control. 54. A method for generating an image with a light projection system with three primary colors, being blue, green, and red, wherein each primary color is respectively defined by a first, second, and third waveband, the method comprising: generating laser light from a first blue laser source emitting a first beam from a fourth waveband, the first blue laser source having a first laser control, generating laser light from a second blue laser source emitting a second beam with a central wavelength and a fifth waveband, the second waveband blue laser source has a second laser control, generating a converted light beam from a substrate with a wavelength conversion element that emits light at a plurality of wavelengths after absorption of a light beam at an excitation wavelength within the fifth wavelength of the second blue laser source, the substrate being so in an optical job of the second beam is positioned that light emitted or reflected by the wavelength conversion element results in emission of a converted beam with a waveband comprising at least the second and third wavebands, and - combining the first and the converted beam, with the feature that the combination results in a white bundle; and measuring the relative intensity of the first, second, and third wavebands of the white beam. The method of claim 54, further comprising generating laser light from a third red laser source that emits a third beam from the third waveband, wherein the third red laser source has a third laser control.