DEVICE FOR IMPLEMENTING A DETECTION FUNCTION AND METHOD FOR OPERATING SUCH A DEVICE

Abstract

A detection device, which includes a scanning module, a detection module operated at a distance from the scanning module, and an evaluation unit. The scanning module includes a laser light source for generating a laser beam, a deflection unit to deflect the beam, and a control unit for controlling the laser light source and the deflection unit, so that the beam is moved in a scanning pattern. The detection module includes a light detector, with which the light of the beam reflected on an object in the beam path is detected and converted into a received signal. The first laser light source is controlled so that the beam is modulated as a function of its deflection and in this way is provided with synchronization marks. The evaluation unit identifies these synchronization marks in the received signal and synchronizes the received signal with the deflection of the beam based on them.

Claims

1-14. (canceled)

15. A device for implementing a detection function, comprising: a scanning module including at least one first laser light source configured to generate at least one detection laser beam, a deflection unit configured to deflect the at least one detection laser beam, and a control unit configured to control the at least one first laser light source and the deflection unit so that the at least one detection laser beam is moved in a predefined scanning pattern; a detection module including at least one light detector, the at least one light detector configured to detect light of the at least one detection laser beam reflected on an object in a beam path of the at least one laser beam, and configured to convert the detected light into a received signal, the detection module being operable at a physical distance from the scanning module; and an evaluation unit configured to evaluate the received signal; wherein the control unit is configured to control the first laser light source for the detection laser beam in such a way that the detection laser beam is modulated as a function of its deflection and in this way is provided with synchronization marks, and the evaluation unit is configured to identify the synchronization marks in the received signal and to synchronize the received signal with the deflection of the detection laser beam based on the identified synchronization marks.

16. The device as recited in claim 15, wherein the first laser light source is configured to generate the at least one detection laser beam in a non-visible wavelength range, the non-visible wavelength being in the infrared range.

17. The device as recited in claim 15, wherein the deflection unit includes a micro-mirror assembly.

18. The device as recited in claim 17, wherein the micro-mirror assembly includes a two-dimensional micro-mirror or two one-dimensional movable micro-mirrors, for implementing a line-by-line or column-by-column scanning movement of the detection laser beam.

19. The device as recited in claim 15, wherein the evaluation unit is further configured to: a. identify objects as a detection event in the beam path of the detection laser beam based on the received signal, and b. locate the detection event in the scanning pattern based on the received signal, and c. generate at least one predetermined detection control signal based on the identified detection event in combination with the location of the detection event in the scanning pattern.

20. The device as recited in claim 19, wherein at least one data channel configured to transmit detection control signals is provided between the detection module and the scanning module and/or a host system.

21. The device as recited in claim 15, further comprising: a projection unit configured to project pieces of image information on an image surface at least in one area of the scanning pattern.

22. The device as recited in claim 15, wherein the detection laser beam generated by the first laser light source is also used for projection of pieces of image information and the first laser light source is controlled to project the pieces of image information to be projected.

23. The device as recited in claim 15, wherein the scanning module includes at least one second laser light source configured to generate at least one projection laser beam for projecting pieces of image information, the projection laser beam together with the detection laser beam being moved using the deflection unit in the predefined scanning pattern, and the at least one second laser light source being controlled as a function of the pieces of image information to be projected to generate the at least one projection laser beam.

24. A method for operating a device that includes a scanning module and a detection module operable at a physical distance from the scanning module, the method comprising: generating, using at least one first laser light source of the scanning module, at least one detection laser beam for implementing a detection function; deflecting, using a deflection unit of the scanning module, the at least one detection laser beam so that the at least one detection laser beam is moved in a predefined scanning pattern; and detecting, using the detection module, light of the detection laser beam reflected on an object in a beam path of the at least one detection laser beam, and converting the detected light into a received signal; wherein the at least one detection laser beam is modulated as a function of its deflection and in this way is provided with synchronization marks, the synchronization marks being identified in the received signal and the received signal being synchronized with the deflection of the detection laser beam based on the identified synchronization marks.

25. The method as recited in claim 24, wherein the detection laser beam is also utilized for projecting pieces of image information and the at least one laser light source is controlled to project the pieces of image information.

26. The method as recited in claim 24, wherein at least one projection laser beam is generated using the scanning module to project pieces of image information, the projection laser beam together with the detection laser beam being moved in the predefined scanning pattern and the projection laser beam being modulated in accordance with the pieces of image information to be projected.

27. The method as recited in claim 26, wherein the pieces of image information are projected sequentially in the form of pixels, in each case a predefined number of pixels forming an image line or image column, a predefined number of image lines and image columns forming a frame and a sequence of frames forming an image sequence, and the detection laser beam being modulated as a function of a piece of meta-image information, which relates to the instantaneously projected frame and/or to the instantaneously projected image line or image column and/or to the instantaneously projected pixels.

28. The method as recited in claim 27, wherein the detection laser beam is modulated in each case simultaneously with the projection of at least a part of at least one predetermined image line or image column of at least one predetermined frame of an image sequence.

29. The method as recited in claim 24, wherein the detection laser beam is modulated using a predefined signal pattern for generating the synchronization marks.

30. The method as recited in claim 24, wherein the detection laser beam is modulated as a square wave signal having a predetermined fixed frequency or having a frequency which is a function of the deflection of the detection laser beam.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] As discussed above, there are various possibilities for advantageously developing and refining the teaching of the present invention. For this purpose, reference is made, on the one hand, to the following description of exemplary embodiments of the present invention with reference to the figures.

[0020] FIG. 1 schematically shows a block diagram of a device S for implementing a detection function according to one specific embodiment of the present invention.

[0021] FIG. 2 shows an example of the modulation of the detection laser beam according to the present invention.

[0022] FIG. 3 shows a flow chart for the synchronization according to the present invention of the received signal with the transmit signal and with the deflection of the detection laser beam.

[0023] FIG. 4 schematically shows a block diagram of detection module 2 according to one specific embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0024] Device S for implementing a detection function schematically depicted in FIG. 1 includes a scanning module 1, a detection module 2 and an evaluation unit 22 which, in this case, is a component of detection module 2. Detection module 2 is situated at a physical distance from scanning module 1 and is also operable remotely from scanning module 1.

[0025] Scanning module 1 is equipped with a first laser light source 11 for generating a detection laser beam L. The laser light source may be a laser light source in the visible wavelength range or also a laser light source in a non-visible wavelength range such as, for example, an infrared laser, depending on the intended purpose. Another component of scanning module 1 is a deflection unit 12 for detection laser beam L. Deflection unit 12 in the exemplary embodiment depicted herein is intended to be a micro-mirror assembly, which is equipped, for example, with two one-dimensional movable micro-mirrors for implementing a line-by-line or column-by-column scanning movement of detection laser beam L. Finally, scanning module 1 also includes a control unit 13 for controlling first laser light source 11 and deflection unit 12, so that the at least one detection laser beam L is movable in a predefined scanning pattern.

[0026] An important component of detection module 2 is a light detector 21, with which the light of detection laser beam L reflected on an object O in the beam path is detectable and is convertible into a received signal. Light detector 21 could, for example, include at least one photodiode, which converts the incident light into a photocurrent as a function of the intensity of the received light. This signal of the photodiode may be easily filtered, amplified, converted from analog to digital, and then evaluated.

[0027] According to the present invention, first laser light source 11 for detection laser beam L is controllable with the aid of control unit 13 in such a way that detection laser beam L is modulated as a function of its deflection and in this way is provided with synchronization marks. Since the modulation of detection laser beam L directly impacts the intensity of the light received from light detector 21 and, therefore, of the received signal as well, it is possible to identify the synchronization marks in the received signal. According to the present invention, this identification takes place via evaluation unit 22, which is also designed according to the present invention to synchronize the received signal with the deflection of detection laser beam L on the basis of the synchronization marks. In this way, it is possible in each case to assign the received signal a defined position in the scanning pattern. The synchronization of the received signal and transmit signal is explained in greater detail in conjunction with FIGS. 3 and 4.

[0028] In the exemplary embodiment depicted in FIG. 1, detection laser beam L is reflected on a surface O. This may be the surface of a package, for example, which is provided with a bar code or with another visually identifiable feature. In this case, device S according to the present invention may be used to identify the visually identifiable feature. For this purpose, detection laser beam L is guided in a predefined scanning pattern over the visual feature. In the process, the intensity of the reflected light of detection laser beam L varies, since the incident light of detection laser beam L is more or less absorbed depending on the color and nature of surface O. This change of intensity is reflected in the received signal and may be located in the scanning pattern based on the synchronization according to the present invention of the received signal with the deflection of detection laser beam L. In this way, it is possible to also assign the received signal to defined positions on the surface O, which is a prerequisite for the identification of visually identifiable features.

[0029] With the aid of device S according to the present invention, however, it is more generally possible to also identify whether an obstacle is located in the beam path of detection laser beam L and at which position such an object is located in relation to the scanning pattern of detection laser beam L. This allows for the implementation of an interactivity function. For this reason, evaluation unit 22 in this case is also designed to identify objects in the beam path of detection laser beam L as a detection event on the basis of the received signal and to locate such a detection event on the basis of the received signal in the scanning pattern of detection laser beam L. A predetermined detection control signal is also generated on the basis of the identified detection event in combination with the location thereof in the scanning pattern. In the exemplary embodiment described herein, this detection control signal is used to control scanning module 1. For this reason, an interface 23 and a data channel 24 for transmitting detection control signals are provided between detection module 2 and scanning module 1. Thus, an object in the beam path of detection laser beam L may, for example, be translated into a control signal, which causes a switch off of scanning module 1. This may involve a deliberately executed user instruction in the form of a gesture in the beam path of detection laser beam L or also an automatic switch-off as an eye-safety measure. With the aid of the detection control signals, however, another unit could also be controlled, which is either connected directly to detection module 2 or to evaluation unit 22 or is also linked to detection module 2 via a host system.

[0030] To further refine the interactivity function, device S could also be equipped with a projection unit, with which pieces of image information are projectable onto an image surface at least in one area of the scanning pattern of detection laser beam L. In this way, it would be possible, for example, to project a user interface onto the image surface. This could be utilized for inputting differentiated instructions, since it is possible to clearly locate the position of an object such as, for example, the hand of a user, on the projected user interface with the aid of the received signal synchronized according to the present invention.

[0031] It is particularly advantageous if the projection unit is implemented in the form of a laser scanner system and the laser light source for the detection laser beam is a component of this laser scanner system. A laser scanner system generally includes multiple laser light sources, which emit light of varying wavelengths in the visible range. These projection laser beams are modulated in accordance with the image information to be projected and guided with the aid of a deflection unit in a predefined scanning pattern over the image surface, where they preferably overlap. The detection laser beam together with the projection laser beams are advantageously deflected with the aid of the same deflection unit. If the laser light source of the detection laser beam also emits light in the visible range and is controllable in accordance with the pieces of image information to be projected, the detection laser beam may also be utilized for projecting pieces of image information. In some applications, however, it may be advantageous if the detection laser beam is not visible, i.e., for example, is in the infrared wavelength range. In this case, the light detector may be blocked against interfering light and diffused light of the projection laser beams simply with the aid of an infrared filter.

[0032] As previously indicated, there are a number of potential uses for the device according to the present invention for implementing a detection function, the specific individual application determining the evaluation of the received signal. Accordingly, the detection module also supplies application-specific output data. These could, for example, be pieces of image information of a visual feature or also just touch events. Accordingly, transmission channel 24 must satisfy different requirements. If detection module 1 supplies detection control signals for scanning module 2, as previously described, then it has proven advantageous to utilize a bi-directional, asynchronous data channel as a back channel such as, for example, Bluetooth or ZigBee. Such a data channel may then also be utilized for transmitting metadata, which describe the scanning pattern, such as number of lines, line length, line number, synchronization patterns used, frame rate, etc. The data rate and timing accuracy required for such metadata are comparatively low. The metadata may be used for simplifying the synchronization and for enhancing the interference resistance. It is advantageous to know the exact number of projected lines if, for example, parts of the image area are to be completely covered.

[0033] At this point, however, it is once again expressly noted that the synchronization marks themselves are not transmitted via transmission channel 24 from scanning module 1 to detection module 2, but, according to the present invention, are sent to detection module 2 together with the laser light of detection laser beam L emitted by scanning module 1.

[0034] At least one second laser light source 14 is optionally also provided for generating at least one projection laser beam for projecting pieces of image information. The projection laser beam in this case is moved together with the detection laser beam in a predefined scanning pattern with the aid of deflection unit 12. The at least one second laser light source 14 in this case is controlled as a function of the pieces of image information to be projected for generating the at least one projection laser beam.

[0035] FIG. 2 serves to explain the modulation according to the present invention of the detection laser beam for generating synchronization marks, which are transmitted together with the light of the detection laser beam from the scanning module to the detection module of a device according to the present invention. As previously mentioned, the present invention is directed to the movement of the detection laser beam in a predefined known scanning pattern. This may be any scanning pattern such as, for example, a Lissajous curve. If the present invention is implemented in conjunction with a scanning projection of pieces of image information, then the scanning movement of the detection laser beam takes place together with the projection laser beams frequently line-by-line or column-by-column in frames. The pieces of image information are then projected sequentially in the form of pixels, in each case a predetermined number of pixels forming an image line or image column, a predetermined number of image lines and image columns forming a frame and a sequence of frames forming an image sequence. In this case, the detection laser beam is advantageously modulated as a function of a piece of meta-image information, which relates to the instantaneously projected frame and/or to the instantaneously projected image line and image column and/or to the instantaneously projected pixels. This is illustrated by FIG. 2, where the amplitude profile of the light intensity of the detection laser beam for the individual scanning lines of such a frame-by-frame scanning movement is depicted. In the case described herein, the scanning movement is intended to run from top to bottom and the synchronization is to take place frame-by-frame. For this purpose, the detection laser beam is provided here in each case in the first line of a frame with a square wave signal of a fixed predefined modulation frequency, which is based on the clock frequency of the deflection unit and corresponds to the pixel frequency of the simultaneously projected image frame. Another synchronization pattern may, however, be just as easily utilized such as, for example, a sawtooth signal. In some cases therefore, it may also be meaningful to utilize a variable modulation frequency, for example, if the synchronization is to take place in stages, initially coarse, then becoming increasingly finer. In the present case, the first line, i.e., a margin, is provided with synchronization marks. An arbitrary other image line may, in principle, also be utilized for the synchronization, however. In each case, both pieces of information about the scanning pattern, i.e., in this case, the number of pixels per line, the number of lines per frame and the clock frequency of the scanning module, as well as pieces of information about the type of the synchronization marks and their arrangement, i.e., in this case, the modulation signal shape and modulation frequency, must be available to the evaluation unit for the synchronization, so that the synchronization marks thus generated may be identified in the received signal and assigned to the corresponding positions in the scanning pattern. Beginning from the second line, the intensity of the detection laser beam in this case is raised each time at the beginning of the line from a base level to an elevated level in order to be lowered to the base level again at the end of the line. This modulation may also be identified in the received signal and be used for the synchronization.

[0036] At this point, it is also noted that the detection laser beam emitted by the scanning module as well as the received signal received by the detection module may be considered to be a classic serial data stream. Accordingly, the synchronization methods and synchronization patterns used in serial data transmission may also be utilized.

[0037] The modulation frequency, meaningfully used for generating the synchronization marks, is selected as a function of the reception characteristics, i.e., of the characteristics of the light detector and of the downstream signal processing and evaluation unit. Bandwidth and pass frequency, in particular, should be considered in this case.

[0038] In the case of scanning laser projectors, the pixel clock is usually significantly higher, for example, in the range of 85 MHz, than the bandwidth of the receiver circuit of the detection module, which is usually merely in the range of 100 kHz to 7 MHz. The significantly higher transmission frequency of the scanning module allows for a very fine modulation of the detection laser beam in this case.

[0039] The method according to the present invention for synchronizing the received signal with the deflection or scanning movement of the detection laser beam is explained below with reference to the flow chart of FIG. 3. In initial situation S1, the digitized received signal is not synchronizedasyncwith the scanning movement of the detection laser beam. In step S2 the received signal is processed and evaluated with the aim of identifying particular signal patterns, which are known to the detection module as synchronization markssearch for pattern. This signal evaluation is performed until a corresponding signal pattern has been identified, which is queried in step S3found potential pattern?. As explained in conjunction with FIG. 2, it is possible to both identify the first frame line and to ascertain the instantaneous clock frequency of the detection laser beam based on the synchronization marks. The synchronization in S4 is based on this instantaneous clock frequencytry to sync, which is explained in greater detail in conjunction with FIG. 4. The steps S2 through S4 are repeated until it is possible to successfully perform this synchronization step S4, which is queried in step S5sync success?. Only then does situation S6 occur, in which the digitized received signal is synchronized with the scanning movement of the detection laser beamsync. In steps S6 and S7, the received signal continues to be receivedS6: receive image dataand evaluatedS7: check next pattern, in order to identify synchronization marks. Based on these synchronization marks, it is then checked in step S9 whether the received signal is still synchronized with the scanning movement of the detection laser beamsync valid. Only when this is no longer the case does the method start from the beginning again, i.e., jumps back to step S2. Otherwise, steps S7 through S9 are continually repeated.

[0040] Detection module 2 depicted in FIG. 4 includes a photodiode 21 as a light detector, which converts the incident light of the detection laser beam into a photocurrent. This analog signal is initially pre-processed in a filter and amplification unit 221 before it is converted into a digital received signal by an analog-digital converter 222. The present invention aims at synchronizing this digitized received signal with the detection laser beam emitted by the scanning module and to thus correlate it with the scanning movement of the scanning module. For this purpose, the digitized received signal is evaluated with the aid of a signal processing and evaluation unit (sync pattern detector) 223, in order to identify particular signal patterns known to the detection module as synchronization marks. The synchronization marks are evaluated in order to ascertain the clock frequency of the scanning module and to determine any deviation of this clock frequency from the scanning frequency of the digitized received signal. The result of this check is fed to a regulating unit (control loop) 224 as an error measure which, based on this error measure, determines an actuating variable control for a clock-pulse generator (ADC clock control) 225, which is connected to analog-digital converter 222. In this way, the clock signal clk of the analog-digital converter is adapted to the clock frequency of the scanning module and the scanning of the received signal is thus synchronized with the respective instantaneous clock frequency of the scanning module. This adaptation is also referred to as clock recovery. The synchronization marks allow not only for a clock recovery, but also supply pieces of information about the instantaneous deflection of the detection laser beam in the scanning pattern, which is utilized for the subsequent signal evaluation of the synchronized received signal.

[0041] The synchronized received signal is also provided to an additional signal processing unit 226 (further data processing). Here, the actual function of the device according to the present invention is implemented, i.e., for example, the identification of individual visual features on a scanned surface or an interactivity function.