Method and apparatus for laser projection

Abstract

The invention relates to a method for laser projection and a laser device (10) for carrying out the method. According to the invention, a method is provided by means of a laser device (10) comprising: a laser generating unit (12), by means of which a laser beam (14) can be generated; a deflection device (16), by means of which the radiation angle of the laser beam (14) can be adjusted in order to deflect the laser beam (14) along a predetermined trajectory (18); the invention relates to a method for navigating a laser beam (14) along a predetermined trajectory (18), comprising a laser generating unit (12) for generating a laser beam (14), and a control device (20) which is coupled to the laser generating unit (12) and by means of which the power of the laser beam (14) can be adjusted, in a first step, in order to navigate the laser beam (14) along the predetermined trajectory (18), a plurality of navigation angles to be controlled by means of a deflection device (16) are determined, each navigation angle being assigned a starting power, the initial power predefines the power of the laser beam (14) when the laser beam (14) is deflected between two navigation angles, and in a next step, an expected dwell duration of the laser beam (14) in the navigation section (22) is determined as a function of the number of navigation angles to be actuated directly in succession, the laser beam (14) reaches the navigation section (22) of the reference surface (24) at the navigation angle, and the laser beam (14) reaches the navigation section (22) at the navigation angle at least for a part of the number of the navigation angles, and a respective starting power of the laser beam (14) is set to a predeterminable target power in each case as a function of the determined dwell duration.

Description

Technical Field

[0001] The invention relates to a method for laser projection by means of a laser device and to a laser device which is designed to carry out the method according to the invention. Background Art

[0002] Laser projectors are used in very different technical fields in order to project contours and markings onto objects. Usually, the contours and marking lines can be projected onto flat or arched surfaces or any other contoured surfaces in a monochrome, i.e., for example, red, green or blue, or in a multi-color, especially mixed color, projection in a well-visible manner. Often, CAD data is used as the basis for projection, which is processed into projection data and transmitted to one or more projectors. Industrial laser projection systems generate virtual but visible templates on the object to be processed, which do not touch or dirty the surface. Technically, projection is usually performed with the aid of one or more galvanometers, with which a mirror can be changed in its orientation relative to the laser beam. The laser beam is deflected by the mirror, wherein the rotation angle of the mirror determines the direction of deflection. If two or more galvanometers are combined with each other, every accessible point in space can be irradiated.

[0003] In order to comply with safety regulations regarding the use and application of lasers, it is necessary to limit the power output by the laser projector depending on various variables, such as the location or purpose of use. The risk of injury to people who are in the emission area that can be reached by the laser is particularly important here. In particular, unprotected viewing of high-power lasers can lead to damage to the retina and thus possibly limited vision. Summary of the invention

[0004] The object of the present invention is to provide a method and a device for laser projection which allow the intensity of the laser beam to be adjusted to a predeterminable level in a simple manner.

[0005] This object is achieved by the method according to the invention as claimed in claim 1 and by the device according to the invention as claimed in claim 17. Advantageous embodiments are given in the dependent claims.

[0006] According to the invention, a method for laser projection by means of a laser device is provided, the laser device comprising: a laser generating unit, by means of which a laser beam can be generated; a deflection device, by means of which a radiation angle of the laser beam can be adjusted in order to deflect the laser beam along a predetermined trajectory; and a control device coupled to the laser generating unit, by means of which the power of the laser beam can be adjusted, wherein in a first step, a plurality of navigation angles to be controlled by means of the deflection device are determined in order to guide the laser beam along the predetermined trajectory, wherein a starting power is respectively assigned to the navigation angles, which starting power predetermines the power of the laser beam when deflecting between two navigation angles, and in a next step, a dwell time to be expected of the laser beam in a navigation segment is determined as a function of the number of navigation angles to be controlled directly in succession, at which the laser beam reaches the navigation segment of a reference surface, and at least for a portion of the navigation angles at which the laser beam reaches the navigation segment, and the respective starting power of the laser beam is respectively adjusted to a predeterminable setpoint power as a function of the determined dwell time.

[0007] The present invention makes it possible to provide a laser projector that can be operated while complying with a predetermined laser safety class. For example, by using the method according to the present invention, a laser projector can be provided that meets the standards for laser class 2 and laser class 3B that can be derived from a predetermined safety policy. When a certain laser class is met, it can be achieved, for example, that the laser projector according to the present invention can be used even without a laser safety officer that is usually required for operation in an enterprise. Compliance with a certain laser class can already be achieved by limiting the total power that can be emitted by means of the laser projection device. For example, compliance with laser class 3B can be achieved when the total power of the laser projection device does not exceed 500mW.

[0008] Laser class 2 can likewise be achieved by selecting a laser diode with a maximum emitted power of 1 mW. For use in a projector, a power of 1 mW is of course unsuitable, since the projection would not be bright enough for its intended use due to the usual distances from the projection surface and the high speeds at which the laser beam is usually deflected.

[0009] To solve this problem, a safety zone can be defined, wherein outside the safety zone, predeterminable criteria, for example, criteria for laser class 2, are met, and within the safety zone, other criteria are met, which require classification into a higher laser class. The method according to the invention is based on the idea of ​​applying the safety criteria for pulsed beam sources, in particular regardless of whether a pulsed or non-pulsed radiation source is used to generate the laser beam. Thus, for example - based on currently valid safety regulations - instead of power, the laser beam can now be placed on the sleeve ( )The energy when the shading object is 7mm is considered to comply with the standards required for a certain laser class.

[0010] The energy of the laser beam when it is applied to a defined surface segment can be determined based on the dwell time of the laser beam within the surface segment, knowing the power emitted by the laser generating unit. In a method of the type according to the invention, the trajectory to be swept by the laser beam is usually determined by sequentially controlling the individual predetermined navigation angles by means of a deflection device. The navigation angles are controlled successively at short intervals of time. Each navigation angle is also usually assigned a laser power, which determines the laser power for this navigation angle.

[0011] If the time intervals between the individual actuated navigation angles are at least largely the same, the dwell time of the laser beam in a specific navigation segment can be determined, for example, by multiplying the number of navigation angles to be actuated in succession by the time interval at which the navigation segment is reached. For example, the time interval between two successively actuated navigation angles can be 2 μs. The time interval can be predetermined by a time constant, which the controller uses as a process time between the individual control steps.

[0012] In order to predetermine the curve to be projected by the laser device, it can be provided in the first step that vector graphics, for example in SVG or DXF format, are provided. These vector graphics are usually processed by means of a computer processing method provided for this purpose and decomposed into individual elements such as arcs, lines and spline curves. These data are then transmitted to the laser projection device. The laser projection device receives the data and processes these data by means of a control device so that an angle Phi, an angle Theta and a determined laser power are respectively configured in a predeterminable time segment, for example 2μs. The solid angle composed of the angle Phi and the angle Theta to be controlled by the deflection device can also be called the navigation angle. This process is called trajectory.

[0013] After the trajectories are created, a further step is performed in which the method steps according to the invention are carried out in order to enable compliance with a certain laser class. After the preparation according to the invention, the data can be transferred to a controller which, by means of a galvanometer drive and a laser drive, periodically and in real time moves away from the predetermined trajectory by means of the navigation angle. The cycle frequency, i.e. the repetition rate, of the trajectory is typically between 30 and 50 Hz.

[0014] In the inventive setting of the theoretical power of the laser beam, it is taken into account that the output power emitted by the laser generation unit is set. When using a laser generation unit comprising a plurality of laser sources, the laser power of the individual sources is preferably set so that the energy to be expected in the navigation section, which results from the power and dwell time of the laser beam, is not exceeded.

[0015] In one embodiment, it is considered that in order to adjust the starting power to a theoretical power based on a predetermined starting power of the laser beam, an actual energy to be expected to be applied by means of the laser beam in the navigation section of the reference surface is determined, and when the actual energy exceeds a predeterminable first limit energy, the starting power is reduced to the theoretical power in each case in such a way that an actual energy to be expected is reached, which is less than or equal to the limit energy.

[0016] The adjustment of the starting power assigned to the navigation angle to the setpoint power can be implemented in such a way that all starting powers to be adjusted are respectively reduced or increased by a certain factor. When using a plurality of laser sources, for example, each starting power to be adapted is reduced or increased by a certain factor, in which the laser powers of the respective laser sources are respectively assigned to the navigation angle.

[0017] The method according to the invention provides for the power to be adjusted to the target power before activation of the laser so that the laser does not exceed a predefinable power or energy limit value during activation and thus immediately upon activation of the laser it is ensured that a certain laser class is adhered to.

[0018] In addition to a reduction in the starting power to the setpoint power, an increase in the starting power is also conceivable. For example, an increase can be implemented when the actual energy to be expected from the laser beam in the navigation segment is less than a predeterminable limit energy. If the dwell time of the laser beam in the navigation segment does not exceed a certain extent, so that without adaptation the predetermined limit energy or limit power of the laser beam in the considered navigation segment is already below, it can also be provided that the starting power is not changed.

[0019] The actual energy to be expected and to be applied by means of the laser beam in the navigation section of the reference surface can be calculated, for example, by means of equation G1.

[0020]

[0021] In which, for equation G1 and also applies: E ist is the actual energy; t i is the time interval between the previous and considered navigation angle i; P i is the starting power of the laser source of the laser beam configured for the considered navigation angle i; S i is the scaling factor of the laser source; a is the first navigation angle considered and n is the last navigation angle considered.

[0022] In equation G1, a sum is formed for a certain number of successive navigation angles a to n, wherein the duration t i The laser power P of the laser source isi and the proportionality factor S i In case of more than one source, the equation is correspondingly multiplied by the laser power P of the additional sources. xi and the proportionality factor S xi Extension. The actual energy, for example when using a laser generating unit comprising two laser sources, can be determined with the aid of equation G2.

[0023]

[0024] Usually in laser projectors of the same type, the duration t between two navigation angles i i The duration is thus determined, for example, by the time constant t K , especially the regulator constant formation. In the case of use, the time constant t K It can be 2μs.

[0025] The limit energy can be determined for different laser power levels to be achieved. For example, the limit energy for laser level 2 can be determined with the aid of equation G3.

[0026] E grenz =7×10 -4 ×T 0.75 ×C6 (G3)

[0027] In which, for equation G3 and furthermore: E grenz is the limit energy; T is the dwell time of the laser beam in the considered navigation segment; C6 is a dimension factor for the degree of focusing of the laser beam. When using parallel-directed, i.e. collimated lasers, in which the beam diameter is in particular 7 mm or less, for example, a value of 1 can be selected for the dimension factor C6. When using expanded laser beams, this expansion is correspondingly taken into account by the dimension factor. Preferably, in the method according to the invention, a collimated laser beam with a beam diameter of less than 7 mm is used.

[0028] The limit energy for laser class 3R can be determined, for example, with the aid of equation G4.

[0029] E grenz =3.5×10 -3 ×T 0.75 (G4)

[0030] The sum of the time intervals between the considered navigation angles i results in the dwell time T. If the time intervals are respectively identical, ie present as time constants, the dwell time T can be formed by multiplying the time constant by the number of navigation angles to be actuated directly in succession, with which the laser beam reaches the considered navigation segment of the reference surface.

[0031] If the determined actual energy is above the limit energy to be below, it is considered that the starting power of the considered navigation angle is multiplied by a correction factor in order to reduce the expected actual energy of the laser in the considered navigation segment to a level at or below the limit energy. The correction factor can be determined, for example, with the aid of equation G5.

[0032]

[0033] According to a preferred embodiment, it can be further provided that a segment power to be expected, to be output by means of the laser beam in a navigation segment of a first reference surface, is determined based on the theoretical power of the laser beam, the segment power is compared with a predeterminable limit power, and when the expected segment power exceeds the limit power, at least for a portion of the navigation angles, the laser beam reaches the navigation segment at the navigation angle, and the theoretical power is reduced in each case so that the expected segment power is less than or equal to the limit power.

[0034] Here, it is tested whether the segment power achieved with a predetermined setpoint power or starting power is outside a certain protection range below a limit power to be lowered, as long as the power assigned to the navigation angle does not change. If the segment power to be expected at a distance from the protection range is greater than the limit power to be lowered, the setpoint power of at least a portion of the navigation angles, in particular all the navigation angles, at which the laser beam reaches the considered navigation segment is proportionally reduced.

[0035] In this specific embodiment, it is further provided that, in order to determine the segment power, the segment energy to be expected to be applied in the navigation segment is first determined and is linked to the repetition rate of the predetermined trajectory.

[0036] The segment energy can be determined, for example, using equation G1 or, when using multiple laser sources, using an adapted equation, such as equation G2, wherein the actual energy corresponds to the segment energy. The segment power can be determined, for example, by multiplying the segment energy by the repetition rate of the track using equation G6.

[0037] P Abschnitt =E Abschnitt ×f TR (G6)

[0038] In which, for equation G6 and furthermore: P Abschnitt is the section power; E Abschnitt is the segment energy and f TR is the frequency or repetition rate of the trajectory, ie, for example, the number of repetitions of the trajectory that are to be projected per second.

[0039] In another embodiment, it is contemplated that for at least one navigation segment reaching the reference surface, a trajectory segment of a predetermined trajectory is identified, for which the laser beam reaches the navigation segment. By means of the identification of the trajectory segments, it can first be identified whether more than one trajectory segment is within the considered navigation segment, with which the laser beam reaches the considered navigation segment. The total energy of different combinations of these trajectory segments can then be considered in order to determine whether a predeterminable limit energy is exceeded. The trajectory segments are segments of a predetermined trajectory, each consisting of directly successive navigation angles, with which the laser beam reaches the considered navigation segment.

[0040] Furthermore, it is considered that when more than one trajectory segment is identified within the navigation segment, for at least one combination comprising a first trajectory segment and one or more further directly successive trajectory segments, in particular for each combination thereof, a number of navigation angles assigned to the combination of the trajectory segments of the predetermined trajectory comprising the trajectory segments is determined, starting with a first navigation angle of the first trajectory segment of the combination and ending with a last navigation angle of the last trajectory segment of the combination along the trajectory segment.

[0041] The number of possible combinations of different track segments increases with the number of identified segments, and the track segments are respectively in the navigation segment under investigation. The number of the combinations can be determined when using equation G7. The area of ​​the predetermined track that includes the identified track segments of the combination is the track segment configured to the navigation segment. A track segment is configured for each combination of track segments. The track segment starts with the first navigation angle of the first track segment of the combination that is within the navigation segment and ends with the last navigation angle of the last track segment of the combination that is within the navigation segment. Therefore, such a track segment includes all navigation angles that are directly consecutive to each other, starting with the first navigation angle of the first track segment of the combination and ending with the last navigation angle of the last track segment of the combination.

[0042]

[0043] Here, for equation G7 and furthermore: N K is the possible number of combinations, which is determined by the number n of trajectory segments that are within the considered navigation segment. TS Conclude.

[0044] In order to examine the combination, the first track segment and one or more other directly successive track segments are considered respectively. Directly successive track segments are such segments of the track that directly succeed each other in the direction of the temporal sequence of the navigation angles to be controlled or in the direction of movement of the laser along the track, that is, there is no jump of the segments in between, and are also in the navigation segment under examination. Therefore, a combination can include two or more track segments that are within the navigation segment under examination. Of course, here, only the unique passage of the track within a cycle is always examined. Therefore, the track segments within the navigation segment under examination are different segments of the unique passage of the track.

[0045] It is further considered that for at least one combination, in particular for each combination, a reference duration is determined according to the number of navigation angles assigned to the combination, wherein a combination limit energy assigned to the combination is determined according to the reference duration, and for the combination, an expected combination actual energy is determined by the sum of the segment energies, the segment energies respectively corresponding to the expected energies of the trajectory segments of the combination, and the combination actual energy is compared with the combination limit energy, and when the combination actual energy exceeds the combination limit energy, at least for the navigation angles of a portion of the number of the trajectory segments, the starting power or theoretical power of the laser beam respectively assigned to the navigation angle is reduced in such a way that the expected combination actual energy is less than or equal to the combination limit energy.

[0046] As the limit energy E grenz , it is also possible to determine the combined limit energy for different laser power levels to be achieved. Analogously to equation G3, for laser level 2, the combined limit energy can be determined, for example, using equation G8.

[0047] E KGE =7×10 -4 ×RD 0.75 ×C6 (G8)

[0048] In which, for equation G8 and furthermore, it applies: E KGE is the combined limit energy; RD is the reference duration for the considered combination; C6 is a size factor for taking into account the focusing degree of the laser beam, which size factor can be around 1, for example, as explained above.

[0049] For example, the combined limit energy for laser class 3R can be determined by analogously using equation G4.

[0050] The reference duration RD can be determined from the sum of the time intervals between the individual navigation angles of the considered combination, starting with the first navigation angle of the first trajectory segment of the combination and ending with the last navigation angle of the last trajectory segment of the combination along the trajectory segment. Thus, not only the navigation angles of the individual trajectory segments of the combination are taken into account, but also the navigation angles between two directly successive trajectory segments. Thus, for example, the reference duration RD can be determined using equation G9.

[0051]

[0052] Wherein, for equation G9 and furthermore, it applies that: RD is the reference duration for the combination under consideration; t i is the time interval between the preceding and considered navigation angle i; a is the first considered navigation angle and n is the last considered navigation angle.

[0053] If the time intervals between two directly successive navigation angles are respectively the same, that is, if there is a time constant t K When the time constant t K The reference duration is determined by multiplication with the number of considered navigation angles n, ie in particular when equation G10 is used.

[0054] RD=n×t K (G10)

[0055] The segment energy can be determined using equation G11. Equation G11 can be applied analogously to equation G1 or, when using multiple sources, in an extended form of equation G11 in analogy to the comments on equation G2. Therefore, further comments are omitted to avoid repetition.

[0056]

[0057] In which, for equation G11 and furthermore, it applies: E SE is the segment energy of the trajectory segment under consideration; t i is the time interval between the previous and considered navigation angle i; P i is the starting power assigned to the considered navigation angle i or the setpoint power of the laser source of the laser beam adapted after using the preceding method steps; S i is the scaling factor of the laser source; a is the first navigation angle and n is the last navigation angle of the considered trajectory segment.

[0058] Similar to the comments on equations G1 and G2, in the same type of laser projector, the duration t between two navigation angles i i Preferably, they are respectively the same.

[0059] In order to adjust the power of the laser beam to such an extent that the combined actual energy is less than or equal to the combined limit energy, it can be provided that the power previously assigned to the considered navigation angle is adjusted to a new power. Analogously to the previous remarks, the laser power previously assigned to the considered navigation angle, i.e. the starting or theoretical power set up to this method step, can be multiplied by a factor. This changes the power values ​​of the considered navigation angles in each case proportionally. The power adjustment can be carried out, for example, using equation G12.

[0060]

[0061] Here, for equation G12 and furthermore: P neu is the adjusted new power assigned to the considered navigation angle; P alt is the old power assigned to the considered navigation angle; E KGE is the combined limit energy; E KIE It is the actual energy of the combination.

[0062] According to a preferred specific embodiment, it is provided that the power of the laser beam is adjusted by means of pulse width modulation.

[0063] Furthermore, it can be provided that the distance of an object detected in the detection range of the distance sensor from the laser device is monitored by means of a distance sensor. This makes it possible to detect that the object is within a predeterminable safety distance. First, it is considered that a person, in particular a person's head, is detected by means of a distance sensor, and the person is within the safety distance.

[0064] In a first aspect, it is provided that the distance sensor only detects when an object is within the set safety distance. Therefore, the detection of the actual distance is not necessary. Therefore, a suitable distance sensor may be provided for detecting an object in the safety range by means of a threshold value being exceeded. Alternatively or additionally, it may be provided that the distance sensor is designed and provided for determining the distance of a detected object or for generating a signal by means of which the distance to the object can be determined.

[0065] To increase laser safety, provision can be made to adjust the power of the laser beam as a function of the distance monitored by means of a distance sensor, wherein in particular the laser generating unit is deactivated when a predefinable safety distance is fallen short.

[0066] In one embodiment of the invention, it can be provided that the reference surface is calculated as a virtual surface which extends over an angular range, in particular the entire angular range, of the navigation area reachable by the laser beam. The navigation area reachable by the laser beam essentially determines the solid angle reachable by the deflection device by means of the exit opening of the laser device.

[0067] In order to allow for an equidistant distribution of the navigation segments on the projection area of ​​the laser device, the virtual reference surface has a spherical shape and extends at a distance relative to the laser projection device, wherein the distance of the virtual reference surface corresponds in particular to the safety distance. The distance of the virtual reference surface can be selected, for example, according to given conditions of the location and / or according to predeterminable safety criteria. With the method according to the invention, compliance with laser class 2 or compliance with another laser safety class, for example laser class 3R, is ensured in distance ranges exceeding the safety distance. Of course, the method according to the invention can also be implemented with a plurality of different reference surfaces spaced at different distances, in order, for example, to ensure compliance with different laser safety classes in different distance ranges.

[0068] It is further considered that the reference surface is divided into a grid comprising a plurality of grid cells, wherein each grid cell corresponds to a navigation section that can be reached by the laser beam. The navigation section can have, for example, a rectangular outer contour. In particular, it can be provided that the outer contour of the navigation section is square. For the side length of the rectangular or square navigation section, in principle, any value can be selected, for example, a value for a certain standardized provision. For example, the side length can be between 4 mm or less and 10 mm or more than 10 mm. Preferably, a square outer contour with a side length of 7 mm is considered.

[0069] In particular, in order to generate laser projections of different colors, it can be provided that the laser generation unit has two or more laser beam sources, wherein, in order to generate the laser beam, the radiation generated by means of the two or more laser beam sources is superimposed. For example, it can be provided that a red laser with a starting power of 100% of its maximum power, respectively, assigned to the navigation angle, is used together with a green laser with a starting power of 50% of its maximum power, respectively, assigned to the navigation angle. Different power adjustments of the laser sources enable projections of different mixed colors. In the power reduction according to the invention, in order to comply with the limit energy, it can be provided that the two sources are reduced proportionally, for example, the red laser is reduced to 50% of its respective maximum power and the green laser is reduced to 25% of its respective maximum power. When using multiple laser sources, the individual sources must be specifically adapted, for example by means of individually adjustable pulse width modulation.

[0070] In order to deflect the laser beam in different spatial directions, it is conceivable that the deflection device has at least one movable mirror, in particular at least one galvanometer mirror, by means of which the laser beam can be deflected in order to adjust the emission angle.

[0071] Safety problems may arise if the deflection device remains unintentionally non-functional or the desired deflection speed is not achieved due to a fault. In this case, the actual dwell time of the laser beam in a certain navigation section may be higher than the calculated dwell time. In order to reduce this safety risk, it is conceivable to monitor the predetermined speed of the drive unit of the deflection device with the help of a monitoring device. In this monitoring, it can be provided, for example, to determine whether the actual angle of the deflection device corresponds to a predetermined theoretical angle. The deviation between the actual angle and the theoretical angle is also called "traction error". Alternatively or additionally, it can be provided that the speed resulting from the movement of the two mirror surfaces is tested close to the critical speed. In particular, mirrors that remain completely non-functional, that is, "stuck" mirrors, can also be identified using this monitoring.

[0072] If the theoretical speed of the deflection device is undershot, it can be provided that the laser power is reduced to a level that is not safety-critical. Alternatively or additionally, it can be provided that the laser device is deactivated when the theoretical speed is undershot.

[0073] Finally, according to the present invention, there is also a laser device for laser projection, which comprises: a laser generation unit, by means of which a laser beam can be generated; a deflection device, by means of which the radiation angle of the laser beam can be adjusted in order to deflect the laser beam along a predeterminable trajectory; and a control device coupled to the laser generation unit, by means of which the power of the laser beam can be adjusted, wherein the laser device is designed and arranged to implement the method according to the present invention according to the embodiment described above.

[0074] In particular, advantages, details and further embodiments of the laser device according to the invention emerge from the description of the embodiments of the method according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Further details and embodiments of the present invention are explained with reference to the accompanying drawings. In the drawings:

[0076] Figure 1 A schematic view of a laser device according to the invention is shown;

[0077] Figure 2 A schematic diagram showing the principle of the navigation angle to be controlled by means of the laser device according to the invention;

[0078] Figure 3 A schematic diagram showing a portion of a reference surface including a navigation section;

[0079] Figure 4 Show Figure 3 Schematic diagram of the principle of the navigation section of the reference surface in FIG.

[0080] Figure 5aA schematic diagram showing a navigation segment including a reference surface of a trajectory segment intersecting the navigation segment; and

[0081] Figure 5b A schematic diagram showing each trajectory segment is shown. Figure 5a In the navigation section of . DETAILED DESCRIPTION

[0082] Figure 1 A laser device 10, which is also often referred to as a projector, is shown, which comprises a laser generating unit 12 which generates a laser beam 14. The laser beam 14 is deflected by means of a deflection device 16 in such a way that it sweeps a predeterminable trajectory 18 in the space. The power of the laser generating unit 12 can be adjusted by means of a control device 20 coupled to the laser generating unit 12. The control device 20 and / or another control device provided for this purpose can control the deflection device 16 in such a way that a predetermined navigation angle X( Figure 2 ). The distance sensor 30 can be configured to detect objects in the detection range of the distance sensor 30. The deflection device 16 can be configured to deflect the laser beam 14 to any navigation angle X that is within the navigation area 28. The navigation area 28 can be formed conically in the emission area of ​​the laser device 10. The detection range of the distance sensor 30 is preferably larger than the navigation area 28 that can be reached with the laser beam 14 or at least as large as it.

[0083] As in Figure 1 As schematically shown in FIG. 1 , the laser generating device 12, the control device 20 and the deflection device 16 can be arranged in a common housing 26. The distance sensor can also be arranged in the housing, but can also be arranged on the housing or outside the housing.

[0084] A reference surface 24 is formed in the navigation area 28 of the laser device 10, here spherically formed on the deflection device 16 toward the deflection point of the laser beam 14. The reference surface 24 can be arranged in particular at a safety distance that corresponds to a safety range monitored by the distance sensor 30. The reference surface 24 is a virtually generated spatial surface that is used for the power control of the laser device 10 according to the invention.

[0085] In a special example, on which every embodiment of the present invention can be based, it can be provided in the first standard 1 that the power of the laser source of the laser device is adjusted by two mechanisms. By adjusting the diode current of the laser diode on the laser driver, the maximum laser power that should be emitted can be predetermined. This value is preferably adjusted once and is preferably immutable. On the other hand, the emission power can be adjusted as linearly as possible by pulse width modulation of the signal on the laser diode. For each point of the trajectory, the intensity value that can be adjusted by means of the power value is determined and used, so as to make the projected image appear with the same brightness, for example. The power adjustment can be influenced in order to avoid possible damage to the laser level. The basic frequency of the pulse width modulation is, for example, 20 MHz and has a cycle duration of 50 ns, which can be divided into 271 levels of 184 ps each. These pulses have a minimum length of 184 ps and a maximum length of 50 ns. Therefore, the pulses fall under this standard 1.

[0086] Figure 2 A simple example of a spatial trajectory 18 to be manipulated by means of the laser beam 14 of the laser device 10 is shown purely schematically. The trajectory 18 is formed by manipulating a plurality of navigation angles X. For this purpose, the deflection device 16 is used to successively manipulate the three angular positions X in the space. Figure 2 The navigation angles X1 to X are shown for illustration purposes. i Since the navigation angles X are each activated successively at time intervals of, for example, 2 μs, the distance covered by the laser beam 14 between two navigation angles X is, in an ideal case, a straight line.

[0087] The navigation angle X is formed by two pieces of angle information Phi and Theta. With the angle pair Phi and Theta, any desired solid angle can be controlled within the navigation range 28 of the laser device 10. The angle information Phi and Theta are used to adjust the deflection device 16.

[0088] For each navigation angle X, a power setting of the laser generating unit 12 is assigned, which power setting determines the intensity of the laser beam 14 when the laser beam 14 is controlled between two navigation angles X.

[0089] Figure 3 The schematic diagram shows a virtual reference surface 24 . The reference surface 24 is divided into a grid comprising grid cells 32 which are each designed as a square in the present example, wherein each grid cell 32 corresponds to a navigation section 22 which can be reached by the laser beam 14 . Figure 3 Purely schematically, a path 18 is also shown which is swept by the laser beam 14 . As shown, the laser beam 14 reaches different navigation sections 22 when controlling the navigation angle X of the path 18 .

[0090] Figure 4 Show Figure 3Detail of a navigation segment 22 in FIG. In this schematic detail view, the successively controlled navigation angles X of the sections of the trajectory 18 within the navigation segment 22 are shown. The area of ​​the trajectory 18 within the navigation segment 22 is referred to as the trajectory segment TS. In this schematic diagram, eleven navigation angles X are within the navigation segment 22. At constant time intervals between these navigation angles X, the dwell time of the laser beam 14 within the considered navigation segment 22 can be calculated by multiplying the time constant by the number of navigation angles of the subsegment TS. If the time constant is, for example, 2 μs, then a dwell time of 22 μs is produced (11 x 2 μs).

[0091] In a special example, on which any embodiment of the present invention can be based, as already explained above, it can be provided in the second criterion 2 that the trajectory projection 18 in the projection area 28 is divided on a grid 32 of the reference surface 24. The grid 32 is preferably at a distance from the projector 10 in the safe area in terms of calculation and further preferably has a spherical shape. The entire theoretically achievable area 28 of the projector 10 is covered by the sphere. The preferably square cells of the grid 32 of the sphere preferably have a side length of 7 mm in two directions on the surface of the sphere. Each point of the trajectory 18 is assigned to a cell or a navigation segment 22 of the grid or reference surface 24 by means of its coordinates or navigation angle X.

[0092] For each navigation segment 22 of the reference surface 24, it is known when the laser beam 14 enters the navigation segment 22 and exits again. The portion between the entry and exit of a unit constitutes a pulse or track segment TS. If the same navigation segment 22 is encountered again at a later time in the track 18, this is evaluated as another track segment TS.

[0093] Figure 4 Schematically, for example, Figure 3 In the example of FIG. 1 , a single unit or a single navigation segment 22 is shown. The subregions of the trajectory 18 are symbolically represented by points representing the navigation angles X, which in terms of time each represent a subregion of the trajectory 18 having a constant duration of, for example, 2 μs in each case.

[0094] For criterion 2, the energy is determined for each 2 μs step and is more precisely determined from the known maximum laser power of the source and the power adjustable by pulse width modulation. The sum of all 2 μs steps in the pulse is the pulse energy. The permissible limit value is obtained, for example, using equation G3, including the time, which is determined by multiplying the number of pulses by 2 μs.

[0095] With this example, for example, compliance with laser class 2 can be achieved in a defined safety zone. In a similar manner to laser class 2 for determining a distance from the safety zone, compliance with laser class 3R can be achieved for a distance of, for example, 100 mm in front of the projector. In both cases, a grid with an edge length of 7 mm can be used, which leads to different pulse lengths of the track segment TS and power adjustment values ​​for the considered navigation angle X. In both cases, when the calculated limit value is exceeded, the power value for the navigation angle X of the respectively considered pulse or track segment TS is corrected so that it is below the limit energy.

[0096] In another special example, on which every embodiment of the present invention can be based, it can be provided in a third criterion 3 that the power adjustment of the navigation angle X, for example, corrected after taking into account criterion 2, is re-evaluated. According to this criterion 3, the sum of the energies for all pulses or track segments TS, which occur within a certain time, for example, 0.25 seconds, in a grid cell or a navigation segment 22 is considered. This also includes the repetition of pulses or track segments TS that occur within the considered navigation segment 22 by a projection frequency of, for example, 25 to 50 Hz. In this criterion 3, it can be provided that the total power of a cell or navigation segment 22 in the distance of the protection range must not be greater than 1 mW and must not exceed 5 mW at a distance of 100 mm (refer to laser class 2 or 3R). If this limit should be exceeded, a correction is carried out for the entire cell, that is, for all navigation angles X, at which the laser beam 14 reaches the navigation segment 22. For this purpose, all power values ​​of the navigation angle X of the pulses or track segments TS of the cell or navigation segment 22 are preferably reduced proportionally so that the values ​​are below the limit.

[0097] Figure 5a A further example of a navigation segment 22 comprising a segment of the trajectory 18 is shown in a schematic diagram, wherein four subsegments TS1 to TS4 are located within the navigation segment.

[0098] Figure 5b Schematic diagram Figure 5a 1 to 13 show a comparison of different combinations of sub-segments TS1 to TS4 within the navigation segment 22. Between the sub-segments TS1 to TS4 are intermediate segments Z1 to Z3, which represent a trajectory region that is located along the trajectory 18 between the first trajectory segment TS1 that reaches the navigation segment 22 and the last trajectory segment TS4 that reaches the navigation segment 22 in terms of time and is therefore outside the navigation segment 22.

[0099] Currently, in one pass of the trajectory 18, four trajectory segments TS are within the navigation area 22. According to equation G17, six combinations K1 to K6 can be formed, each of which is formed by two or more trajectory segments TS that are directly successive to each other. Currently, the combination K1 includes trajectory segments TS1 and TS2. Combination K2 includes trajectory segments TS1, TS2 and TS3. The remaining combinations K3 to K6 are formed accordingly. Each combination K defines a trajectory segment TA, which includes the navigation angle X of the trajectory 18, starting with the first navigation angle X of the first trajectory segment TS of the combination K under consideration and ending with the last navigation angle X of the last trajectory segment TS of the combination K under consideration. Currently, the trajectory segment TA1, for example, includes all navigation angles X of the trajectory 18, starting with the first navigation angle X of the first trajectory segment TS1 of the combination K1 under consideration and ending with the last navigation angle X of the last trajectory segment TS2 of the combination K1 under consideration. The remaining trajectory segments TA2 to TA6 are defined accordingly.

[0100] In a special example, on which any embodiment of the invention can be based, it can be provided in the fourth criterion 4 that multiple pulses, that is to say multiple trajectory segments TS, which occur within a period T in the navigation segment 22 are considered. This occurs, for example, when the trajectory 18 intersects itself. The example of a unit or navigation segment 22 comprising multiple trajectory segments TS within a period T is - as mentioned - in Figure 5a In Figure 5b , the temporal course of four track segments TS1 to TS4 within the unit or navigation segment 22 is schematically shown. All four track segments TS are passed within one cycle T of the track 18. Figure 5b The time course can be seen in the diagram of . The diagram shows purely schematically the power P of the track segment TS over time. First, the navigation angle X of the track segment TS1 is controlled, and then the track segments TS2 to TS4 follow. At this point, the cycle T ends and a new passage begins.

[0101] Four individual pulses TS1 to TS4 can already be considered in criterion 2. Since, of course, the pulses can occur irregularly in number, length and distance within a periodic cycle, further virtual pulses, also referred to as track segments TA, must be tested against the limits in criterion 2. This can be done for different laser classes, that is to say, for example, both for laser class 2 and for laser class 3R. Virtual pulses or track segments TA are defined in such a way that a plurality of successive pulses are considered together. Successive pulses or track segments TS of a virtual pulse are also referred to here as combinations K. Specifically, this is done in Figure 5bIn this example unit, which includes four pulses TS1 to TS4, six additional, virtual pulses or track segments TAI to TA6 are defined. With the power and duration of each track segment TA, for example, equations G3 and G4 from criterion 2 can be applied according to the power level under consideration in order to determine the limit values ​​for the corresponding virtual pulses or the corresponding track segments TA. The virtual pulses or track segments TAI to TA6 are Figure 5b , respectively as arrows below the diagram. For a virtual first pulse TA1, the sum of the energies of the two first individual pulses TS1 and TS2 of the combination K1 and the length of the track segment TA1 from the beginning of the track segment TS1 to the end of the track segment TS2, i.e. the reference duration RD, is determined. For a virtual second pulse TA2, the sum of the energies of the three first individual pulses TS1 to TS3 and the length of the track segment TA2 from the beginning of the track segment TS1 to the end of the track segment TS3, i.e. the reference duration RD, is determined. The other virtual pulses TA3 to TA6 are examined accordingly.

[0102] Reference numerals list

[0103] 10 Laser equipment

[0104] 12 Laser generating unit

[0105] 14 Laser Beam

[0106] 16 Deflection device

[0107] 18 Track

[0108] 20 Control device

[0109] 22 Navigation Section

[0110] 24 Reference surface

[0111] 26 Housing

[0112] 28 Navigation Area

[0113] 30 Distance Sensor

[0114] 32 Grid

[0115] X Navigation Angle

[0116] TS track segment

[0117] K combination

[0118] Z Middle

[0119] TA track segment

Claims

1. A method for laser projection by means of a laser device (10), the laser device comprising: a laser generating unit (12), by means of which a laser beam (14) can be generated; a deflection device (16), by means of which a radiation angle of the laser beam (14) can be adjusted in order to steer the laser beam (14) along a predetermined trajectory (18); and a control device (20) coupled to the laser generating unit (12), by means of which the power of the laser beam (14) can be adjusted, characterized in that In a first step, a plurality of navigation angles (X i ) to be controlled by means of the deflection device (16) are determined in order to guide the laser beam (14) along the predetermined trajectory (18), wherein a starting power is respectively assigned to each of the navigation angles (X), which starting power predetermines the power of the laser beam (14) when deflecting between two navigation angles (X), and in a next step, a desired dwell time of the laser beam (14) in a navigation segment (22) is determined as a function of the number of navigation angles (X) to be controlled directly in succession, at which the laser beam (14) reaches the navigation segment (22) of a reference surface (24), and at least for a portion of the number of navigation angles (X) at which the laser beam (14) reaches the navigation segment (22), and the respective starting power (P t of the laser beam (14) is increased or decreased as a function of the determined dwell time. Start ) are adjusted to a predeterminable theoretical power.

2. The method according to claim 1, characterized in that In order to Start ) the starting power (P Start ) is adjusted to the theoretical power (P Soll ), determining the actual energy (E) to be expected and to be applied by means of the laser beam (14) in the navigation section (22) of the reference surface (24) ist ), and in the actual energy (E ist ) exceeds a predeterminable first limit energy (E grenz ), the starting power (P Start ) are reduced to the theoretical power (P Soll ), so that the expected actual energy (E ist ), the actual energy is less than or equal to the limit energy (E grenz ).

3. The method according to claim 1 or 2, characterized in that Based on the theoretical power (P Soll ) determines a segment power (P) to be expected and to be outputted by means of the laser beam (14) in a navigation segment (22) of a first reference plane (24) Abschnitt ), and compares the section power with a predeterminable limit power (P grenz ) and the power in the expected section exceeds the limit power (P grenz ), at least for a portion of the navigation angles (Xi), the laser beam (14) reaches the navigation section (22) at the navigation angle, and the theoretical power (P Soll ), so that the expected section power (P Abschnitt ) is less than or equal to the limit power (P grenz ).

4. The method according to claim 3, characterized in that In order to determine the segment power, the segment energy to be expected to be applied in the navigation segment (22) is first determined and is linked to the repetition rate of the predetermined trajectory (18).

5. The method according to any one of the preceding claims, characterized in that For at least one navigation section (22) of the reference surface (24), a trajectory section (TS) of the predetermined trajectory (18) is identified, for which the laser beam (14) reaches this navigation section (22).

6. The method according to claim 5, characterized in that When more than one trajectory segment (TS) is identified within the navigation segment (22), for at least one combination (K) comprising a first trajectory segment (TS) and one or more further directly successive trajectory segments (TS), in particular for each combination (K), a number of navigation angles (X) assigned to the combination (K) of a trajectory segment (TA) of the predetermined trajectory (18) comprising the trajectory segments (TS) is determined, starting with a first navigation angle (X) of the first trajectory segment (TS) of the combination (K) and ending with a last navigation angle (X) of the last trajectory segment (TS) of the combination (K) along the trajectory segment (TA).

7. The method according to claim 6, characterized in that For at least one combination (K), in particular for each combination (K), a reference duration (RD) is determined as a function of the number of navigation angles (X) assigned to the combination (K), wherein a combination limit energy (E KGE ), and for the combination (K) the segment energy (E SE ) to determine the expected combined actual energy (E KIE ), the segment energies correspond to the expected energies of the trajectory segments (TS) of the combination (K), and the actual energy of the combination (E KIE ) and the combined limit energy (E KGE ) compared with the actual energy (E KIE ) exceeds the combined limit energy (E KGE ), at least for a portion of the navigation angles (X) of the trajectory segment (TA), the starting power or the theoretical power of the laser beam (14) respectively assigned to the navigation angle (X) is reduced so that the expected combined actual energy (E KIE ) is less than or equal to the combined limit energy (E KGE ).

8. The method according to any one of the preceding claims, characterized in that The power of the laser beam (14) is adjusted by means of pulse width modulation.

9. The method according to any one of the preceding claims, characterized in that The distance between an object detected in a detection range of the distance sensor (30) and the laser device (10) is monitored by means of a distance sensor (30).

10. The method according to claim 7, characterized in that The power of the laser beam (14) is adjusted as a function of the distance monitored by means of the distance sensor (30), in particular the laser generating unit (12) is deactivated when a predefinable safety distance is fallen below.

11. The method according to any one of the preceding claims, characterized in that The reference surface (24) is calculated as a virtual surface which extends over an angular range, in particular the entire angular range, of a navigation area (28) reachable by the laser beam (14).

12. The method according to claim 11, characterized in that The virtual reference surface (24) has a spherical shape and extends at a distance from the laser projection device (10), wherein the distance of the virtual reference surface (24) corresponds in particular to the safety distance.

13. The method according to any one of the preceding claims, characterized in that The reference surface (24) is divided into a grid (32) comprising a plurality of grid cells, wherein each grid cell corresponds to a navigation section (22) reachable by the laser beam (14).

14. The method according to any one of the preceding claims, characterized in that The laser generating unit (12) has two or more laser beam sources, wherein the beams generated by means of the two or more laser beam sources are superimposed in order to generate the laser beam (14).

15. The method according to any one of the preceding claims, characterized in that The deflection device (16) has at least one movable mirror, in particular at least one galvanometer mirror, by means of which the laser beam (14) can be deflected in order to adjust the emission angle.

16. The method according to any one of the preceding claims, characterized in that A predetermined speed of a drive unit of the deflection device (16) is monitored by means of a monitoring device.

17. A laser device (10) for laser projection, the laser device comprising: a laser generating unit (12), by means of which a laser beam (14) can be generated; a deflection device (16), by means of which a radiation angle of the laser beam (14) can be adjusted in order to deflect the laser beam (14) along a predeterminable trajectory (18); and a control device (20) coupled to the laser generating unit (12), by means of which the power of the laser beam (14) can be adjusted, wherein: The laser device (10) is designed and arranged to carry out a method according to one of claims 1 to 16.

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