Projection arrangement and method for illuminating a plurality of virtual pixels on a projection surface

Abstract

The invention relates to a projection arrangement for illuminating a plurality of virtual pixels that produce a first individual image during a first time window. The projection arrangement comprises a laser arrangement with a plurality of laser light sources that are designed to emit laser light of substantially the same wavelength via a plurality of emission points arranged at a defined distance from one another. The projection arrangement also comprises a deflection module that is designed to deflect laser light generated by the laser light sources successively onto the plurality of pixels and, during the first time window, to deflect laser light from a first laser light source onto a first pixel and laser light from a second laser light source onto a second pixel within a first sub-time window.In addition, the projection arrangement comprises a control element which is designed to control the plurality of laser light sources and / or the deflection module in such a way that during the first time window a third pixel is illuminated with laser light from the second laser light source within a second partial time window and within a later third partial time window the third pixel is illuminated with laser light from the first laser light source.

Description

[0001] The present invention relates to a projection arrangement for illuminating a plurality of virtual pixels which produce a first individual image during a first time window, and to a method for illuminating a plurality of virtual pixels. BACKGROUND

[0002] LBS (Laser Beam Scanning) devices for NTE (Near to Eye) glasses, also known as data glasses, are becoming increasingly popular and are therefore constantly being developed further. Compared to Liquid Crystal on Silicon (LCoS) LED systems and Digital Light Processing (DLP) LED systems, LBS systems have the advantage that, simply put, only those pixels of a single image (frame) that are illuminated (painted) within the time required to display the single image contribute to energy consumption. This statement is incomplete in that in LBS systems, laser light sources also consume energy in a non-emitting state. However, the energy consumption of an LBS system is lower than that of LCoS LED and DLP LED systems, where the entire image area must be constantly illuminated to display a single image.

[0003] Furthermore, the luminance that a laser light source in an LBS system can deliver is a significant advantage over LED systems. By adjusting the supply current applied to the laser light source and / or by adjusting the illumination time of a pixel, the luminance of the pixel can be increased almost indefinitely compared to LED systems without having to enlarge the optical interface. The brightness dynamics of a laser light source are also high compared to an LED or an OLED.

[0004] However, to achieve high image resolution and brightness, LBS systems rely heavily on the interaction between the laser power and a deflection module for scanning the pixels of a single image. Currently, a limiting factor is the frequency of the deflection module, e.g., a MEMS mirror, which scans and illuminates the individual pixels of each image.

[0005] Furthermore, it was found that despite the existing savings in energy consumption of an LBS system compared to other known systems, especially in the area of ​​compact data glasses, an even further reduction in energy consumption is necessary, since the space available for batteries to provide energy is very limited.

[0006] In summary, there is therefore a need to provide a system, in particular a system for projecting at least one individual image, which is compact, provides high image brightness, provides a high dynamic range in image brightness, provides high image resolution and at the same time has the lowest possible energy consumption. SUMMARY OF THE INVENTION

[0007] This need is addressed by the subject matter of the independent patent claims. Further developments and embodiments of the proposed principle are specified in the subclaims.

[0008] In known LBS systems, each individual laser light source must cover the entire dynamic brightness range in order to be able to image different brightness levels using the laser light source that illuminates a pixel. This often leads to low wall-plug efficiency (WPE) when low brightness is required and to a lack of optical power when high brightness is required. In addition, the energy consumption of such laser light sources during standby mode is very high. This means that the laser light source is operated just below the laser threshold during pixel scanning when the emission of laser light and thus illumination of a pixel is to be suppressed, but a rapid ramp-up to illuminate a subsequent pixel is to be enabled. In simple terms, the higher the maximum optical power of a laser light source, the higher the laser threshold.

[0009] The inventor now proposes a projection arrangement and a method for operating such a projection arrangement, wherein the projection arrangement provides improved brightness and an enlarged accessible brightness range by combining several features and at the same time has reduced power consumption.

[0010] The projection arrangement, in particular an LBS system, uses multiple laser light sources per wavelength or light color in combination with a deflection module designed to simultaneously illuminate multiple virtual pixels of an individual image on a projection surface with the light from the multiple laser light sources. This makes it possible to achieve increased resolution of the individual image at a given raster frequency of the deflection module. Furthermore, the inventor proposes using smaller laser light sources or laser light sources with shorter laser ridges compared to known systems. These laser light sources have a lower average power consumption at the expense of light output but in favor of a lower required threshold current for use in an LBS system.This is because the current required to operate the laser light sources just below the laser threshold is significantly reduced, meaning the laser light sources consume significantly less energy in a so-called standby mode. In order to increase the image brightness, which has been reduced due to the reduced light output, the inventor proposes illuminating the virtual pixels requiring increased brightness multiple times within a single image in order to suggest to the human eye a correspondingly high overall pixel brightness. Although this means that, at a given scanning frequency of the deflection module, a previously achieved increase in resolution must be partially reduced again, a decision can be made on a case-by-case basis as to whether higher image brightness with reduced resolution or lower image brightness with increased resolution is desired.

[0011] The core of the projection arrangement according to the invention lies in the use of a painting scheme, in which a virtual pixel of an individual image can be illuminated multiple times during the duration of the display of the individual image. Theoretically, this can also be achieved by a higher scanning frequency of the deflection module, but since the scanning frequency of known deflection modules is currently a limiting factor in an LBS system, multiple illumination of a virtual pixel within an individual image requires a correspondingly designed deflection module in combination with more than one laser light source per wavelength / color.

[0012] Using such a projection arrangement, at least some of the following advantages can be achieved: ▪ compact form factor (e.g.: < 0.7mm 3 ); ▪ high image brightness & high dynamic range (e.g.: indoor night mode = 300 nt - 500 nt, outdoor beach mode = 10,000 nt), where 1 nt = 1 cd / m 2 ; ▪ low energy consumption (e.g. 100 mW / eye of a user); ▪ high or reasonably high image resolution.

[0013] Furthermore, the projection system according to the invention makes it possible to respond to different conditions depending on the situation. For example, the projection system can continuously switch between different operating modes and / or generate mixed operating modes to optimally adapt the projected image mode to the situation. Possible modes include: (1) High-resolution mode For example, all laser light sources are operated in parallel to display the individual image with as many illuminated virtual pixels as possible. In this mode, the number of illuminated pixels per individual image is maximized (resolution), while the brightness of the individual illuminated virtual pixels of the individual image is reduced. (2) High brightness mode For example, all laser light sources are operated in parallel to illuminate fewer virtual pixels of a single image multiple times during the duration of displaying a single image, thus creating a single image with reduced resolution but increased perceived brightness. In this mode, the image resolution (illuminated pixels / single image) is reduced, while either the absolute brightness of the single image is increased, and / or a high dynamic range in brightness can be achieved. (3) Low brightness mode The low-brightness mode can be implemented with different resolutions depending on requirements. In low-brightness mode, the laser light sources can be operated with low current, and in particular, the illuminated virtual pixels are not illuminated multiple times per frame. With relatively small laser light sources, this mode can be comparatively efficient and energy-saving. (4) Dynamic image resolution The image resolution of each individual image can be adapted to the situation. For example, if the projection setup includes eye tracking of a user of the projection setup, it is possible to support foveated rendering, which can further reduce the overall energy consumption of the projection setup. Foveated rendering is specifically a rendering technique that uses an eye tracker integrated into virtual reality glasses to reduce rendering effort by significantly reducing the image quality / resolution in the peripheral vision area (outside the area viewed by the fovea). (5) Dynamic brightness control The brightness of each individual image can be adjusted depending on the situation. The overlap of augmented reality (AR) with the real world in an AR environment requires a high dynamic brightness range to avoid glare and to make AR information visible even on bright surfaces. Accordingly, it may be possible to adjust the brightness of the individual image or the brightness of successive individual images depending on the situational brightness of the environment.

[0014] According to a first aspect, a projection arrangement is provided for illuminating a plurality of virtual pixels. The plurality of illuminated pixels thereby produces a first individual image during a first time window.

[0015] The number of illuminated virtual pixels used to display the individual image, or which make up the individual image, together with the size of the displayed individual image, is a measure of the image resolution, also known as resolution for short. An individual image displayed using more illuminated virtual pixels has a higher resolution than an individual image of the same size displayed using fewer illuminated virtual pixels. To achieve a higher resolution, an individual image must be displayed using a larger number of illuminated pixels, or using a larger number of illuminated pixels while maintaining the same size of the individual image.

[0016] The term “frame” is to be understood as an image that is displayed for a defined period of time. This period is also referred to below as the time window during which the individual image is displayed or created. In the field of film and video technology, where several individual images are displayed one after the other to show moving images, the period for displaying the individual image is determined by the frame rate (or more precisely, frame rate). The frame rate specifically refers to the number of individual images that are recorded or played back per period of time and is usually given in fps (frames per second), less frequently BpS (image frames / images per second) or Hz (Hertz). The human eye perceives successive images as a moving (but not necessarily smooth) scene at around 14 to 16 images per second (this varies from person to person).However, current frame rates are 24 Hz (for many movies), 48 Hz (for elaborately produced new movies and 3D cinema), 25i / 30i Hz (for television) and 60-390 Hz (for computer games).

[0017] To display a single image, the projection arrangement comprises a laser array with a plurality of laser light sources configured to emit laser light with essentially the same wavelength. Each laser light source is assigned an emission window or emission point through which the laser light sources emit laser light from the laser array. The emission points are arranged at a defined distance from one another.

[0018] In particular, the laser arrangement can be a multi-channel laser, also called a multi-ridge laser, comprising a plurality of laser ridges formed on a common semiconductor substrate. The laser light sources or their emission windows can be arranged at a defined distance from one another, in particular at a distance of less than 30 µm or less than 10 µm. To reduce power consumption, the laser light sources can be relatively small, in particular laser light sources with a reduced laser ridge length.

[0019] The laser ridges can be arranged parallel or stacked on a semiconductor substrate. However, it is also possible for the laser light sources to be formed by individual laser light sources arranged side by side or stacked. Combinations of the above-mentioned designs are also possible.

[0020] However, the laser arrangement can be a photonic integrated circuit (PIC) coupled to a plurality of laser light sources. The emission points are brought together within the waveguides of the PIC, so that the emission points can be spaced apart from one another by, for example, between 3 µm and 5 µm. This type of configuration has the advantage that the laser light sources themselves can be spaced further apart, allowing for better individual heat dissipation during operation. Furthermore, electro-optical interactions between neighboring laser light sources can be better reduced.

[0021] In order to be able to illuminate the individual image or the virtual pixels of the individual image with more than just one wavelength / color, the projection arrangement can comprise a plurality of laser arrangements, wherein the laser light sources of each laser arrangement are designed to emit light of a different wavelength / color. For example, the projection arrangement can comprise three laser arrangements, wherein the laser light sources of a first laser arrangement are designed to emit red light, the laser light sources of a second laser arrangement are designed to emit green light, and the laser light sources of a third laser arrangement are designed to emit blue light. This can result in a so-called RGB projection arrangement, by means of which the virtual pixels of an individual image can each be illuminated with the colors red, green, and blue, from which colors any further desired color can be mixed.

[0022] The projection arrangement also comprises a deflection module designed to deflect laser light generated by the laser light sources sequentially onto the plurality of pixels to be illuminated. The deflection module can in particular be designed to deflect light from the laser light sources sequentially, for example row by row and column by column, onto the virtual pixels of the individual image on the projection surface to be illuminated. For this purpose, the deflection module can, for example, be designed to be movable in order to deflect light from the laser light sources sequentially onto the virtual pixels of the individual image on the projection surface to be illuminated, for example at periodic intervals within the time window for displaying the individual image. Such periodic deflection of the light from the laser light sources onto the virtual pixels of the individual image on the projection surface can in particular also be referred to as scanning the pixels or painting the pixels.

[0023] For example, the deflection module can be designed to scan a certain number of positions, also called theoretical pixels, on, for example, a projection surface or a projection plane at a defined frequency. These positions or theoretical pixels can in particular be arranged in columns and rows and in particular be equidistant from one another in the horizontal and vertical directions. The number of positions or theoretical pixels can in particular be determined by the maximum size of an image to be displayed, the maximum possible scanning frequency of the deflection module, the length of the time window for displaying an individual image and optionally by a number of positions or theoretical pixels that the deflection module can simultaneously illuminate per scanning position. Accordingly, a theoretical pixel pitch can result because the deflection module scans per time window.

[0024] In this regard, it should be noted that the number of illuminated pixels resulting in a single image may differ from the number of theoretical pixels. However, it is also possible for the number of illuminated pixels resulting in a single image to be identical to the number of theoretical pixels. Illuminating all theoretical pixels results in a single image with the maximum possible resolution, whereas illuminating only a portion of all theoretical pixels results in a single image with reduced resolution.

[0025] The time for scanning the pixels can, for example, result from the time window for displaying the individual image and the number of theoretical pixels and can be referred to below in particular as a partial time window. For example, the time for scanning the pixels, i.e. a partial time window, can result from the time window for displaying the individual image divided by the number of theoretical pixels. The time for scanning the pixels, i.e. a partial time window, can correspondingly also result from the time window for displaying the individual image and the number of scanning positions of the deflection module, whereby the number of scanning positions can differ from the number of virtual pixels to be illuminated. For example, the time for scanning the pixels, i.e. a partial time window, can result from the time window for displaying the individual image divided by the number of scanning positions of the deflection module.The period of a partial time window is in particular a real sub-range of a time window and is accordingly shorter than the period of a time window.

[0026] For example, the deflection module can comprise movable parts and be formed, for example, by one or more MEMS mirrors that deflect the light from the laser light sources onto the virtual pixels of the individual image on the projection surface to be illuminated. For example, the deflection module can be formed by at least two mirrors arranged in series, in particular MEMS mirrors, each of which moves or oscillates about an axis. The mirrors can oscillate about two axes that are essentially perpendicular to one another, so that one mirror scans the columns of a theoretical pixel array in sequence, for example, and the other mirror scans the rows of the theoretical pixel array at a slower frequency. However, the reverse order is also possible. The deflection module can also be formed by one or more mirrors that oscillate simultaneously about two axes that are essentially perpendicular to one another.Preferably, the mirror oscillates around both axes at a natural frequency (-> low energy consumption) so that the mirror(s) scan a pattern that deviates from a Cartesian pixel pitch, in particular so-called Lissajous figures. In both cases, a virtual pixel is illuminated when the geometric condition of the laser light source and mirror position allows it. Since the individual emission points of the laser array are spatially separated from one another, it is possible to illuminate a virtual pixel with light from different laser light sources. In this way, multiple laser light sources can be superimposed to illuminate a virtual pixel.

[0027] However, it is also possible for the deflection module to be formed by or comprise one or more polygon mirrors. The polygon mirrors can rotate about two essentially perpendicular axes, so that one polygon mirror scans, for example, the columns of a theoretical pixel array in sequence, while the other polygon mirror scans the rows of the theoretical pixel array at a slower frequency. However, the reverse order is also possible. It is also possible for the deflection module to comprise non-moving parts and still provide the desired functionality. For example, the deflection module can comprise one or more so-called optical phased arrays (OPAs). Phased array optics is a technology for controlling the phase and amplitude of light waves transmitted or reflected from a two-dimensional surface using adjustable surface elements.By dynamically controlling the optical properties of a surface at the microscopic level, it is possible to direct the direction of light beams without moving parts. This allows the creation of diffractive optical elements such as dynamic virtual lenses, which serve not only for alignment but also for beam focusing or splitting. Dynamic phase variation can also be used to create real-time holograms. Using such a deflection module, the light from the laser light sources can be redirected in the desired manner to the virtual pixels of the individual image on the projection surface to be illuminated.

[0028] According to the invention, the deflection module is designed to simultaneously deflect laser light from a first laser light source onto a first pixel and laser light from a second laser light source onto a second pixel during a first time window within a first sub-time window, in particular during a scanning position of the movable deflection module. Accordingly, several virtual pixels can be illuminated simultaneously during a sub-time window.

[0029] In the case of a one-piece element or interconnected elements, the deflection module can be designed such that, at the time of a scanning position, it simultaneously deflects the light from, for example, two adjacent emission points and thus two laser light sources to two different pixels. At a time of a subsequent scanning position, for example after the deflection module has been moved, the deflection module can then simultaneously deflect the light from the adjacent laser light sources to two other pixels. Alternatively, in the case of multiple separate elements, the deflection module can be designed such that, at the time of a scanning position, a first element of the deflection module deflects light from a first laser light source to a first pixel and, at the same time, a second element of the deflection module deflects light from a second laser light source to a second pixel.At a time of a subsequent scanning position, the elements of the deflection module can then, after the movement has taken place, deflect the light from the two laser light sources to two other pixels.

[0030] The projection arrangement further comprises a control element configured to control the plurality of laser light sources and / or the deflection module such that, during the first time window, a third pixel is illuminated with laser light from the second laser light source within a second sub-time window, and, within a later third sub-time window, the third pixel is illuminated with laser light from the first laser light source. During the time window for displaying an individual image, one or more, or all, of the virtual pixels to be illuminated can be illuminated consecutively with light from several of the laser light sources. This can increase the perceived brightness of the illuminated pixels.However, at a given scanning frequency of the deflection module, this means that not all theoretical pixels can be illuminated, and thus the resolution of the individual image must be reduced at least partially by simultaneously illuminating several pixels. However, a decision can be made on a case-by-case basis whether higher image brightness with reduced resolution or lower image brightness with increased resolution is desired.

[0031] For the purposes of the description, a “first” and a “second”, for example a “first” partial time window and a “second” partial time window or a “first” laser light source and a “second” laser light source, mean in particular two different areas, elements, time periods or objects.

[0032] The projection arrangement can in particular be designed to illuminate the virtual pixels on a projection surface or projection plane. A projection surface can in particular be understood to be a surface onto which the image to be projected is projected. Examples of this can be a projector by means of which an image is projected onto a wall or a screen. However, if an image is to be generated in the eye, for example using data glasses, a distinction can be made between generating an image onto a projection plane or alternatively generating an image onto a projection surface. There are basically two options for generating an image in the eye. (A) Systems that work with a waveguide. Here, an image is generated on a virtual intermediate plane / projection plane. The image is then replicated multiple times in two spatial directions within the waveguide. This creates an eye box. The eye box is generally the area in which the viewer's eye can perceive an image. In the case of a waveguide system, for example, this is an area in the lens of a spectacle from which a copy of the multiple-replicated image of the virtual intermediate plane falls into the eye. (B) In a retinal scan, spatial information about the virtual pixel to be illuminated in the image to be generated is converted into angular information. To generate an image in the eye (on the retina), a mirror, e.g., in the form of a holographic mirror invisible to the viewer, is incorporated into the lens of a pair of data glasses. The projection plane / surface can also be located directly in the eye, on the viewer's retina.

[0033] In some aspects, the projection arrangement is configured to display a second individual image during a second time window after displaying a first individual image during a first time window. The first and second individual images can, in particular, differ from one another, so that moving images, at least as perceived by the human eye, can be generated by means of the projection arrangement.

[0034] In some aspects, the projection arrangement further comprises a light-shaping optic arranged between the laser arrangement and the deflection module. The light-shaping optic is designed in particular to collimate the laser light emitted by the laser arrangement so that essentially collimated laser light impinges on the deflection module. Essentially collimated can be understood in particular to mean that the laser light is collimated as far as possible and has a tendency towards focusing rather than light scattering. The light-shaping optic can be designed such that the light spot of the laser light is very small in the region of the virtual pixels to be illuminated. For example, if 100% collimation is not possible, the laser light can have a focal point between the deflection module and the virtual pixels to be illuminated.

[0035] In some aspects, the control element is configured to operate the plurality of laser light sources in a pulsed manner. In particular, the laser light sources can be operated in a pulsed manner within a partial time window such that they are operated above their laser threshold for a maximum of 60% of the time of a partial time window, in particular a maximum of 40% of the time of a partial time window.

[0036] In continuous wave (CW) mode, there is a risk of laser light sources rolling over even at low optical output power, due to their difficulty cooling. In an operating mode with a limited laser duty cycle (e.g., 10% - 20%) and short pulse modulation (e.g., 2 ns - 5 ns), heat dissipation between current pulses allows for a much higher drive current without thermal rollover.

[0037] In particular, the maximum optical power of a laser or laser light source is limited by rollover. This is the thermal overload of the laser due to self-heating. Laser light sources with a shorter laser ridge have a smaller cooling cross-section and are therefore more likely to overheat. Since the rollover point of a laser is strongly influenced by the power output (self-heating) and the cooling, excessive self-heating can be counteracted when using comparatively small laser light sources by operating the laser light sources in pulsed mode. In pulsed operation with long intervals between current pulses, the rollover point shifts to higher optical powers, so that the laser light sources can be operated below this critical optical power without overheating.

[0038] The use of small laser light sources, which are also operated in pulsed mode, therefore has the advantage that the laser light sources have a relatively low laser threshold, yet can be operated efficiently above the laser threshold without overheating. This allows the laser light sources to operate with a high WPE, and due to the low laser threshold, the proportion of the required threshold current to the total current can be reduced. Accordingly, the energy consumption of the projection arrangement can be reduced.

[0039] Pulsed operation of the laser light sources during the partial time windows can also result in the laser light sources being activated for only a very short period of time, a few nanoseconds. This means that, in the case of laser light sources comprising a laser ridge, the laser ridge does not settle cleanly within this short time (the modes cannot develop perfectly). This can result in a broadening of the emission spectrum emitted by the laser light sources of up to 2 nm in pulsed operation compared to continuous-wave operation, for example.A possible difference of up to 2 nm in the laser light emitted by the laser light sources can lead to a slightly shifted, broadened emission spectrum compared to the other laser light sources, so that a pixel illuminated multiple times using these laser light sources is illuminated with laser light with a spectral width of possibly 3 nm to 5 nm. Superimposing the light from the pulsed laser light sources can, with a minimal difference (offset) in the respective emitted laser light, lead to a spectral broadening of the entire laser light emitted onto a virtual pixel. This can, for example, suppress optical artifacts in the projection arrangement.

[0040] In some aspects, the plurality of laser light sources have a low threshold current limit. For example, the threshold current limit at an operating temperature of approximately 25°C for a green or red light-emitting laser light source can be less than 30 mA, in particular less than 25 mA, and for a red light-emitting laser light source can be less than 10 mA, in particular less than 6 mA. In particular, the laser light sources are designed or configured such that their threshold current is as low as possible. This is achieved, for example, by the use of comparatively short laser ridges. In this way, the required power consumption in the standby mode of the laser light sources can be reduced and power consumption can be kept to a minimum.

[0041] In some aspects, the control element is designed to operate laser light sources that are not supposed to emit any light within a partial time window below their laser threshold, but in particular with a current greater than 0 or just below the laser threshold. Such operation can in particular be referred to as standby mode of the laser light sources and can be used to enable the laser light source to be activated quickly if a virtual pixel to be illuminated is to be illuminated using light from the laser light source when the individual image is scanned and does not first have to be fully started up. In addition, a distinction can be made in standby mode as to whether the laser light sources are operated in a "standby mode" just below the laser threshold, for example with a current of approximately 60% to 80% of the threshold current limit, or whether the laser light sources are operated in a "rest mode" with only a current of approximately10% to 30% of the threshold current limit. This may depend, in particular, on whether the laser light source needs to be activated in the foreseeable future to illuminate a virtual pixel.

[0042] In particular, the control element can be configured to take into account the image information of the image to be projected and to place laser light sources that do not need to be activated for several partial time windows into a sleep mode, while placing these laser light sources into standby mode shortly before they need to be activated, so that they can be activated within the shortest possible time. This approach can also reduce the energy consumption of the projection arrangement.

[0043] In some aspects, the control element and / or the deflection module is configured to illuminate a first subset of the theoretical pixels multiple times with laser light from the plurality of laser light sources during the first time window and to illuminate a second subset of the theoretical pixels with laser light only with one of the plurality of laser light sources or not at all. As a result, in particular virtual pixels of an individual image to be illuminated can be illuminated more brightly than other regions in order, for example, to display different brightnesses of regions of the individual image during an individual image. In addition, isolated symbols can be displayed in this way, wherein only pixels that represent the symbol can be illuminated or can be illuminated more brightly.

[0044] In some aspects, the plurality of virtual pixels to be illuminated are arranged in rows and columns and, in particular, are arranged equidistant from one another. In some aspects, the plurality of virtual pixels to be illuminated are arranged closer to one another in a first region than in a neighboring second region. In the latter case in particular, in a first region of the theoretical pixels, for example, some of the theoretical pixels may be unilluminated, whereas in a second region of the theoretical pixels, several or all of the theoretical pixels are illuminated. The illuminated virtual pixels are correspondingly further apart from one another in the first region, so that the resolution in this region is reduced, whereas in the second region they are closer together, i.e. the resolution is increased.However, it is also possible that the theoretical pixels already have more densely packed areas and less densely packed areas due to the design of the deflection module, so that an illumination of the theoretical pixels can lead to virtual pixels to be illuminated that are arranged at different densities to one another.

[0045] In some aspects, the projection arrangement further comprises an ambient light sensor configured to detect a brightness or a brightness level of the surroundings of the projection arrangement. The control element is further configured to illuminate a first subset of the theoretical pixels multiple times with laser light from the plurality of laser light sources during the first time window as a function of a sensor signal from the ambient light sensor and to illuminate a second subset of the theoretical pixels with laser light from only one of the plurality of laser light sources. As a result, pixels of an individual image, in particular, can be illuminated more strongly than other regions in order, for example, to display different brightnesses of regions of the individual image during an individual image.This can be advantageous, for example, in unfavorable light and shadow conditions, when certain areas of the projection setup are located in brighter surroundings than others. Furthermore, the sensor signal from the ambient light sensor can be used to accommodate different ambient brightness levels when switching between two individual images, so that, for example, a first individual image can be displayed brighter than a subsequent or later second individual image.

[0046] In some aspects, the control element and / or the deflection module is configured to illuminate each of the theoretical pixels at most once with laser light from each of the plurality of laser light sources during a second time window. Accordingly, dynamic resolution can be provided by the projection arrangement in that more of the theoretical pixels can be illuminated for a second frame than for the first frame.

[0047] A further aspect relates to data glasses comprising a projection arrangement according to some of the aforementioned aspects. The projection arrangement is designed to project a plurality of virtual and illuminated pixels into at least one eye of a user of the data glasses. In particular, these can be AR glasses or VR glasses, for example.

[0048] In some aspects, the data glasses additionally comprise a sensor for detecting the viewing direction of a user of the data glasses. In particular, the direction in which a user of the data glasses is looking can be checked essentially in real time. The control element and / or the deflection module can further be configured, during the first time window and depending on a sensor signal from the sensor for detecting the viewing direction, to repeatedly illuminate pixels located in a central region of the user's viewing direction with laser light from the plurality of laser light sources and to illuminate pixels located in an edge region surrounding the central region with laser light from only one of the plurality of laser light sources. As a result, regions of the individual image that lie in the user's field of vision can be displayed brighter than regions of the individual image that lie in an edge region surrounding the field of vision.However, it is also possible to explicitly illuminate areas that are not in the user's direct field of vision much brighter, for example to direct the user's field of vision in that direction or to warn the user, for example.

[0049] In some aspects, the control element and / or the deflection module is configured, during the first time window and depending on a sensor signal from a sensor for detecting the viewing direction, to illuminate areas that lie in a central area of ​​the user's viewing direction with a higher resolution, i.e., to illuminate, for example, the maximum possible theoretical pixels in this area, and to illuminate areas that lie in an edge area surrounding the central area with a lower resolution, i.e., to illuminate a smaller number of pixels in this area than the possible theoretical pixels. As a result, areas of the individual image that lie in the user's field of view can be displayed with a higher resolution than areas of the individual image that lie in an edge area surrounding the field of view.

[0050] According to a further aspect, a method for illuminating a plurality of virtual pixels is proposed, wherein the plurality of pixels produce a first individual image during a first time window. The method can be carried out, in particular, with a projection arrangement according to some of the above aspects, so that the aspects described for the projection arrangement can also apply equally to the method.

[0051] The procedure includes the following steps: Operating a laser arrangement having a plurality of laser light sources configured to emit light having substantially the same wavelength via a plurality of emission points arranged at a defined distance from one another, such that the laser light sources emit laser light in the direction of a deflection module; Deflecting the laser light emitted onto the deflection module successively onto the plurality of virtual pixels to be illuminated, wherein the deflection module is designed such that, during a first time window within a first sub-time window, laser light from a first laser light source is simultaneously deflected onto a first pixel and laser light from a second laser light source is simultaneously deflected onto a second pixel; and Controlling the plurality of laser light sources and / or the deflection module such that during the first time window a third pixel is illuminated with laser light from the second laser light source within a second partial time window and within a later third partial time window the third pixel is illuminated with laser light from the first laser light source.

[0052] In some aspects, the step of operating the plurality of laser light sources comprises a pulsed operation of the plurality of laser light sources, in particular such that the laser light sources are operated above their laser threshold within a partial time window for at most 60% of the time of a partial time window, in particular for at most 40% of the time of a partial time window.

[0053] In some aspects, the step of operating the plurality of laser light sources comprises operating laser light sources that are not scheduled to emit light within a partial time window below their lasing threshold.

[0054] In some aspects, the step of controlling the plurality of laser light sources and / or the deflection module comprises illuminating a first subset of the plurality of pixels multiple times with laser light from the plurality of laser light sources during the first time window and illuminating a second subset of the plurality of virtual pixels with laser light from at most one of the plurality of laser light sources.

[0055] In some aspects, the step of controlling the plurality of laser light sources and / or the deflection module comprises that the plurality of virtual pixels are projected, for example, onto a projection surface or a projection plane in rows and columns, wherein the pixels are arranged in particular equidistant from one another; or that the plurality of virtual pixels are projected, for example, onto a projection surface or a projection plane in a first area with a closer distance to one another than in an adjacent second area.

[0056] In some aspects, the step of controlling the plurality of laser light sources and / or the deflection module comprises illuminating each pixel of the plurality of virtual pixels forming a second individual image at most once with laser light from each of the plurality of laser light sources during a second time window. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Further aspects and embodiments according to the proposed principle will become apparent with reference to the various embodiments and examples which will be described in detail in conjunction with the accompanying drawings. Fig. 1 shows a projection arrangement and a step of a method according to the proposed principle; Fig. 2 shows a projection arrangement and a further step of a method according to the proposed principle; Fig. 3 shows a projection arrangement and a further step of a method according to the proposed principle; Fig. 4 shows schematically the illumination of a virtual pixel by means of a projection arrangement according to the proposed principle; Fig. Figure 5 schematically shows the illumination of several virtual pixels within a first time window by means of a projection arrangement according to the proposed principle. DETAILED DESCRIPTION

[0058] The following embodiments and examples show various aspects and their combinations according to the proposed principle. The embodiments and examples are not always true to scale. Likewise, various elements may be shown enlarged or reduced in size to emphasize individual aspects. It goes without saying that the individual aspects and features of the embodiments and examples shown in the figures can be easily combined with one another without compromising the inventive principle. Some aspects have a regular structure or shape. It should be noted that in practice, slight deviations from the ideal shape may occur without, however, contradicting the inventive idea.

[0059] Furthermore, the individual figures, features, and aspects are not necessarily depicted in the correct size, nor are the proportions between the individual elements necessarily accurate. Some aspects and features are emphasized by being enlarged. However, terms such as "top," "above," "below," "below," "larger," "smaller," and the like are correctly depicted in relation to the elements in the figures. This makes it possible to infer such relationships between the elements from the illustrations.

[0060] The Fig. 1 to 3 show a projection arrangement 1 for illuminating a plurality of virtual pixels 2 on a projection surface 3. On the projection surface 3, the illuminated virtual pixels form a single image, which is displayed or generated, in particular, during a first time window. By way of example, only the actual virtual pixels to be illuminated are shown in the figures, and the number of theoretical pixels that could be projected using the arrangement 1 can also be larger.

[0061] In the illustrated case, the virtual pixels 2 are shown as an example on a flat projection surface 3. However, the pixels can also be located in a virtual projection plane or intermediate plane, as may be the case, for example, if the individual image is to be projected into the eye of a user of the projection arrangement.

[0062] The projection arrangement 1 comprises a laser arrangement 4 with a plurality of laser light sources 5a, 5b, 5c, which are arranged at a defined distance from one another and are designed to emit laser light L1, L2, L3 with essentially the same wavelength. In the illustrated case, the laser arrangement 1 is formed by a multi-laser, which comprises three laser ridges 5a, 5b, 5c, each with a light exit window located at one end of the laser ridge. The laser ridges are formed on a common semiconductor substrate and have a lateral distance of less than 10 µm from one another.

[0063] The projection arrangement 1 further comprises a light-shaping optic 7, which is arranged between the laser arrangement 4 and a deflection module 6 in the beam path of the laser arrangement 4. The light-shaping optic 7 is designed to shape and, in particular, substantially collimate the laser light L1, L2, L3 emitted by the laser arrangement 4.

[0064] The deflection module 6 is designed to deflect laser light L1, L2, L3 generated by the laser light sources 5a, 5b, 5c sequentially onto the plurality of virtual pixels 2. For this purpose, the deflection module is designed such that it is movable, in particular rotatable, about at least one axis, in the illustrated case about at least two axes. This is indicated in the figures by the two axes shown in dashed lines, one horizontal and one vertical, as well as by the arrows at the end of the axes.

[0065] In addition, the deflection module 6 is designed, as in Fig. 1, during a first time window and within a first sub-time window, laser light L1 from a first laser light source 5a is simultaneously directed onto a first pixel 2a of the plurality of virtual pixels 2, laser light L2 from a second laser light source 5b onto a second pixel 2b of the plurality of virtual pixels 2, and laser light L3 from a third laser light source 5c onto a third pixel 2c of the plurality of virtual pixels 2, without substantially moving in the process. In the case shown, this is shown as an example for three laser light sources, the light of which can be simultaneously directed by the deflection module onto three different pixels. However, it should be understood that this can also be done in a similar manner with more or fewer laser light sources, or that the light from all or a subset of the laser light sources can also be directed onto the same pixel simultaneously.It should also be understood that combinations of the above options are possible.

[0066] In addition, the projection arrangement 1 comprises a control element (not shown) which is designed to control the plurality of laser light sources 5a, 5b, 5c and / or the deflection module 6 in such a way that, as shown in Fig. 2, during the first time window, the third pixel 2c of the plurality of virtual pixels 2 is illuminated with laser light L2 of the second laser light source within a second sub-time window and within a later third sub-time window, as in Fig. 3, the third pixel 2c is illuminated with laser light L1 from the first laser light source 5a. Accordingly, during the first time window, the virtual pixels to be illuminated can be illuminated not only by laser light from one laser light source, but also by laser light from multiple laser light sources, so that the perceived brightness of these multiply illuminated virtual pixels is increased. This is particularly advantageous when using laser light sources that have lower optical power than laser light sources from known LBS systems. This allows virtual pixels to be efficiently illuminated with low luminance, for example, only with light from one laser light source, depending on the requirements, and simultaneously virtual pixels to be illuminated with high luminance by illuminating the virtual pixel with laser light from multiple laser light sources, so that the perceived overall brightness is still high.

[0067] This is summarized and exemplarily shown in the form of graphs in the Fig. 4 for an exemplary pixel. In addition, Fig. 4 shows the characteristic curve of the individual laser light sources in order to explain the advantage of smaller laser light sources, especially when stand-by mode is required.

[0068] The laser characteristic curve has the shape of a hockey stick. From zero to the threshold value, a current I flows without any significant light emission P. Only at currents I above the threshold value does the laser ridge begin to lase (stimulated emission) and deliver up to a connected current I f a high luminance P optAlthough the time from zero to the operating range of a laser is only a few nanoseconds, the laser must be operated just below the threshold if immediate switch-on characteristics are required (NTE, frequency 0.2 GHz). This causes permanent energy consumption. In general, the higher the maximum optical power of a laser, the higher the laser threshold. Therefore, one idea of ​​the invention is to reduce the laser threshold by reducing the size of the laser light sources and to compensate for the resulting lost light power due to the reduced size by multiple illumination of the pixels to be illuminated. Although this cannot reduce the energy consumption required to illuminate the pixel to be illuminated with the same brightness, it can significantly reduce the current used in standby times between pixel illuminations.

[0069] The graphs on the left show the individual laser characteristics for the Fig. 1 to 3, each of which can be activated within a partial time window and redirected to a virtual pixel to illuminate it. Above the threshold value, the laser light sources can be adjusted along the laser characteristic curve up to an optimal luminance P opt with a connected current I f Depending on the connected current, the emitted luminance can be adjusted for each laser light source above the laser threshold. The graph on the right, however, shows a sequence of individual laser characteristics for one pixel as an example. This illustrates that a comparable optical luminance P can also be achieved using several smaller laser light sources. opt as can be achieved using a larger laser light source.

[0070] Fig.Figure 5 also shows, as an example for a time window, that different pixels 2a, 2b, 2c can be illuminated with different brightnesses. This can be achieved, on the one hand, by adjusting the emitted luminance of a laser light source (compare L1 pixel 2a and L2 pixel 2b) and / or by increasing the luminance of a pixel by illuminating a pixel with light from multiple laser light sources (L1 + L2 + L3) during the time window, so that the perceived overall brightness of the pixel is increased. LIST OF REFERENCE SYMBOLS 1 projection arrangement 2, 2a, 2b, 2c, 2d, 2e pixels 3 Projection surface, projection plane 4 Laser arrangement 5a, 5b, 5c Laser light source 6 Deflection module 7 light-shaping optics L1, L2, L3 laser light T1, T2 time window T1, t2, t3 partial time windows

Claims

[1] Projection arrangement (1) for illuminating a plurality of virtual pixels (2, 2a, 2b, 2c), wherein the plurality of virtual pixels (2, 2a, 2b, 2c) produce a first individual image during a first time window (T1), comprising: a laser arrangement (4) having a plurality of laser light sources (5a, 5b, 5c) which are designed to emit laser light (L1, L2, L3) having substantially the same wavelength via a plurality of emission points arranged at a defined distance from one another; a deflection module (6) which is designed to deflect laser light (L1, L2, L3) emitted by the emission points successively onto the plurality of virtual pixels (2, 2a, 2b, 2c), and which is designed to deflect laser light (L1) from a first laser light source (5a) onto a first pixel (2a) of the plurality of virtual pixels and laser light (L2) from a second laser light source (5b) onto a second pixel (2b) of the plurality of virtual pixels during the first time window (T1) within a first sub-time window (t1); and a control element which is designed to control the plurality of laser light sources (5a, 5b, 5c) and / or the deflection module (6) in such a way that during the first time window (T1) a third pixel (2c) of the plurality of virtual pixels is illuminated with laser light (L2) from the second laser light source (5b) within a second partial time window (t2) and within a later third partial time window (t3) the third pixel (2c) is illuminated with laser light (L1) from the first laser light source (5a). [2] Projection arrangement according to claim 1, wherein the control element is designed to operate the plurality of laser light sources (5a, 5b, 5c) in a pulsed manner, in particular such that the laser light sources (5a, 5b, 5c) are operated above their laser threshold for at most 60% of the time, in particular for at most 40% of the time, within a partial time window (t1, t2, t3). [3] Projection arrangement according to claim 1 or 2, wherein the control element is designed to operate laser light sources (5a, 5b, 5c), which are not intended to emit light within a partial time window (t1, t2, t3), below their laser threshold. [4] Projection arrangement according to one of claims 1 to 3, further comprising a light-shaping optic (7) which is arranged between the laser arrangement (4) and the deflection module (6) and which is designed in particular to collimate the laser light (L1, L2, L3) emitted by the laser arrangement (4). [5] Projection arrangement according to one of claims 1 to 4, wherein the control element and / or the deflection module (6) is designed to illuminate a first subset of the plurality of virtual pixels (2, 2a, 2b, 2c) repeatedly with laser light from the plurality of laser light sources (5a, 5b, 5c) during the first time window (T1) and to illuminate a second subset of the plurality of virtual pixels (2, 2a, 2b, 2c) with laser light from one of the plurality of laser light sources (5a, 5b, 5c). [6] Projection arrangement according to one of claims 1 to 5, wherein the plurality of virtual pixels (2, 2a, 2b, 2c) are arranged in rows and columns and in particular are arranged equidistant from one another. [7] Projection arrangement according to one of claims 1 to 5, wherein the plurality of virtual pixels (2, 2a, 2b, 2c) are arranged closer to one another in a first region than in an adjacent second region. [8] Projection arrangement according to one of claims 1 to 7, further comprising an ambient light sensor, wherein the control element is designed to illuminate a first subset of the plurality of virtual pixels (2, 2a, 2b, 2c) repeatedly with laser light from the plurality of laser light sources (5a, 5b, 5c) during the first time window (T1) as a function of a sensor signal from the ambient light sensor and to illuminate a second subset of the plurality of virtual pixels (2, 2a, 2b, 2c) with laser light from one of the plurality of laser light sources (5a, 5b, 5c). [9] Projection arrangement according to one of claims 1 to 8, wherein the control element and / or the deflection module (6) is designed to illuminate each pixel of the plurality of virtual pixels at most once with laser light (L1, L2, L3) of each of the plurality of laser light sources (5a, 5b, 5c) during a second time window (T2). [10] Data glasses (10) comprising a projection arrangement (1) according to one of claims 1 to 9, wherein the projection arrangement (1) is designed to project the plurality of virtual pixels (2, 2a, 2b, 2c) into at least one eye of a user of the data glasses. [11] Data glasses according to claim 10, further comprising a sensor for detecting the viewing direction of a user of the data glasses, wherein the control element and / or the deflection module (6) is designed to illuminate virtual pixels lying in a central region of the viewing direction of the user multiple times with laser light from the plurality of laser light sources (5a, 5b, 5c) during the first time window (T1) and as a function of a sensor signal from the sensor, and to illuminate virtual pixels lying in an edge region surrounding the central region with laser light from at most one of the plurality of laser light sources (5a, 5b, 5c). [12] Method for illuminating a plurality of virtual pixels (2, 2a, 2b, 2c), wherein the plurality of virtual pixels (2, 2a, 2b, 2c) produce a first individual image during a first time window (T1), comprising the steps: Operating a laser arrangement (4) with a plurality of laser light sources (5a, 5b, 5c) which are designed to emit light with substantially the same wavelength via a plurality of emission points arranged at a defined distance from one another, such that the laser light sources (5a, 5b, 5c) emit laser light (L1, L2, L3) in the direction of a deflection module (6); Deflecting the laser light (L1, L2, L3) emitted onto the deflection module (6) successively onto the plurality of virtual pixels (2, 2a, 2b, 2c), wherein the deflection module (6) is designed such that during the first time window (T1) within a first partial time window (t1), laser light (L1) from a first laser light source (5a) is deflected onto a first pixel (2a) of the plurality of virtual pixels and laser light (L2) from a second laser light source (5b) is deflected onto a second pixel (2b) of the plurality of virtual pixels; and Controlling the plurality of laser light sources (5a, 5b, 5c) and / or the deflection module (6) in such a way that during the first time window (T1) a third pixel (2c) of the plurality of virtual pixels is illuminated with laser light (L2) from the second laser light source (5b) within a second partial time window (t2) and within a later third partial time window (t3) the third pixel (2c) is illuminated with laser light (L1) from the first laser light source (5a). [13] Method according to claim 12, wherein the step of operating the plurality of laser light sources (5a, 5b, 5c) comprises a pulsed operation of the plurality of laser light sources (5a, 5b, 5c), in particular such that the laser light sources (5a, 5b, 5c) are operated above their laser threshold for at most 60% of the time, in particular for at most 40% of the time, within a partial time window (t1, t2, t3). [14] The method of claim 12 or 13, wherein the step of operating the plurality of laser light sources (5a, 5b, 5c) comprises operating laser light sources (5a, 5b, 5c) that are not intended to emit light within a partial time window (t1, t2, t3) below their laser threshold. [15] Method according to one of claims 12 to 14, wherein the step of controlling the plurality of laser light sources (5a, 5b, 5c) and / or the deflection module (6) comprises that during the first time window (T1) a first subset of the plurality of virtual pixels (2, 2a, 2b, 2c) is illuminated multiple times with laser light from the plurality of laser light sources (5a, 5b, 5c) and a second subset of the plurality of virtual pixels (2, 2a, 2b, 2c) is illuminated with laser light from at most one of the plurality of laser light sources (5a, 5b, 5c). [16] Method according to one of claims 12 to 15, wherein the step of controlling the plurality of laser light sources (5a, 5b, 5c) and / or the deflection module (6) comprises that the plurality of virtual pixels (2, 2a, 2b, 2c) are projected in particular onto a projection surface (3) or a projection plane in rows and columns, wherein the virtual pixels are arranged in particular equidistant from one another; or that the plurality of virtual pixels (2, 2a, 2b, 2c) are projected in particular on a projection surface (3) or a projection plane in a first region with a closer distance to one another than in an adjacent second region. [17] Method according to one of claims 12 to 16, wherein the step of controlling the plurality of laser light sources (5a, 5b, 5c) and / or the deflection module (6) comprises that during a second time window (T2) each pixel of the plurality of virtual pixels is illuminated at most once with laser light (L1, L2, L3) of each individual one of the plurality of laser light sources (5a, 5b, 5c).

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