The present invention relates to a hand-guided marking system. In particular, the invention relates to a hand-guided marking system that is equipped with a radiation source for applying a marking on a surface of a workpiece. The hand-guided marking system is further provided with a camera and at least one lighting device for lighting at least one part of the surface of the workpiece. 
     BACKGROUND 
     From the prior art it is known to apply safety designations on workpieces. Usually, these safety designations are applied by a laser on the surface of the workpiece. These safety designations or markings are also called “data matrix codes” (DMC). 
     From the German publication DE 10 2008 000 503 A1, a method for verifying data matrix codes is known. During a processing procedure, a marking is applied on workpieces. The workpiece then can be permanently identified with reference to this marking. For verifying the applied marking, a camera is connected to the laser marking system. The data matrix code applied to the workpiece is read with this camera and compared with the desired code and verified. 
     The German publication DE 10153943 A1 discloses a laser writer and a method for applying a matrix code on an object. The device contains a laser for generating a laser beam and a deflection unit for focusing and guiding the laser beam within a marking field on the object or workpiece. For reading the matrix code generated on the object, the laser writer also contains a reading device. The field of view of the reading device can be set by the deflection unit at least to one part of the marking field that contains the matrix code. For steering the laser to the marking field or for the simultaneous guiding of the light from the marking field to the reading device, a dichroic beam splitter is provided in the beam path. 
     The German publication DE 103 08 684 A1 discloses a method for the quality inspection of two-dimensional matrix codes on metallic workpieces with an image-processing device. The matrix code is applied in the form of marking dots on the metallic workpieces. The embossing procedure for the marking dots is performed with reference to specified digital position data by a marking tool. Then the corresponding image data for testing is recorded by the image processing device only at the positions specified by the position data. 
     US Patent application US 2004/0099724 A1 discloses a workpiece with a machine readable data carrier. The data carrier comprises a two-dimensional matrix code. The matrix code is produced on the workpiece by means of holes. A mechanical processing is preferred, because the burn-in process for the code by a laser can lead to structural changes of the material. Before the workpiece is mounted in the holder for the application of the matrix code, the matrix code is checked by a reading device. 
     DE 100 59 246 A1 is likewise concerned with a marking system in which a radiation source emitting a laser beam is arranged within a housing. In addition, a scanning device that steers the laser beam in a protective housing is located in the housing. 
     From DE 199 15 071 A1, another marking system is known in which a radiation source is arranged within a protective housing on a guide and not, like in the marking system according to the invention, in a support frame outside of the protective housing. 
     SUMMARY 
     The object of the invention is to create a hand-guided marking system in which different radiation sources can be used in a simple way and satisfies the safety conditions for the radiation sources used. 
     The objective is achieved by a hand-guided marking system having one or more features of the invention. 
     The hand-guided marking system supports a protective housing on a support frame. The protective housing has an opening that is opposite the surface of the workpiece on which the marking is to be applied. The radiation source can be mounted in the support frame such that an optical axis of the radiation source runs through the opening of the protective housing. 
     The radiation source is a laser that is mounted in a laser carrier in the support frame. The laser carrier has a laser base that supports several guide elements for the insertion of the radiation source. The laser base further has an opening that is used for holding at least one part of an optical system of the radiation source. 
     The laser carrier is provided with at least one handle element for manual handling. An attachment for machine handling can also be mounted. On the attachment, the hand-guided marking system can be lowered onto the workpiece on whose surface the marking is to be applied. Preferably, the markings to be applied are data matrix codes (DMC). For testing the quality of the applied marking, a camera is mounted on the protective housing. By means of the camera, the light reflected back from the surface of the workpiece is recorded and thus the applied marking is imaged on an image capture chip of the camera. It is apparent for someone skilled in the art that the camera includes the optical system necessary for the imaging. 
     A pivoting mirror is mounted in the interior of the protective housing. The pivoting mirror can be pivoted into a first position and into a second position. In the first position, the light from the radiation source runs along the optical axis of the radiation source to the surface of the workpiece, in order to form the corresponding marking there. In the second position, the mirror is arranged such that the light from the radiation source is blocked and the light reflecting from the surface of the workpiece is directed onto the camera. 
     The protective housing itself carries a base plate in which the opening is provided for the passage of the light of the radiation source. The opening of the base plate of the protective housing is opposite the surface of the workpiece. At least one safety initiator is mounted on at least one outer wall of the protective housing. The safety initiator determines whether the hand-guided marking system is positioned correctly with respect to the workpiece. This prevents an output of light from the radiation source out of the protective housing and switches off the radiation source if the protective housing is not mounted correctly. The radiation source is switched off based on the signal of the safety initiator. Another possibility is to pivot the mirror into the second position based on the signal from the safety initiator and in this way to block the light coming from the radiation source. 
     The lighting device is arranged on at least one inner wall of the protective housing, in order to provide the diffuse lighting required for an image capture by the camera. 
     For applying the safety markings on the surface of workpieces, lasers are used as the radiation sources. The safety markings are designated as data matrix codes (DMC). For applying the safety designation or marking, portable systems are used. The hand-guided marking system according to the invention is provided with a protective housing. This protective housing has all of the required safety devices (especially the safety initiators). The camera is used for inspecting the safety marking applied to the surface of the workpiece and is here mounted directly on the protective housing. The hand-guided marking system is suitable especially for the laser marking of large bearings, wherein, due to the dimensions of the bearings, it does not make sense to build corresponding stationary and fixed housings or arrangements in order to provide the workpieces with the laser marking. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Below, embodiments should explain the invention and its advantages with reference to the accompanying figures. The size relationships in the figures do not always correspond to the real size relationships, because some shapes are shown simplified and other shapes are shown enlarged with respect to the other elements for better illustration. In the drawings: 
         FIG. 1  is a perspective view of the hand-guided marking system according to the invention, 
         FIG. 2  is a perspective view of the support frame from above, wherein no radiation source is inserted in the support frame, 
         FIG. 3  is a perspective view of the support frame from below, wherein the opening in the base plate of the protective housing can be seen, 
         FIG. 4  is a section view through the protective housing of the hand-guided marking system, wherein the pivoting mirror is located in the first position, 
         FIG. 5  is a section view of the protective housing shown in  FIG. 4 , wherein the pivoting mirror is located in the second position, and 
         FIG. 6  is a schematic view of a part of the workpiece in which a marking is formed on the surface of the workpiece. 
     
    
    
     For elements of the invention that are identical or have identical actions, identical reference symbols are used. Moreover, for the sake of clarity, only reference symbols that are required for describing the particular figure are shown in the individual figures. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a perspective view of the hand-guided marking system  1  according to the invention. The hand-guided marking system  1  comprises a radiation source  2  that is designed as a laser. The hand-guided marking system  1  further comprises a camera  4  with which the markings  100  applied on the surface  101  of a workpiece  102  can be read or verified (see, in this context,  FIG. 6 ). The hand-guided marking system  1  is further provided with a protective housing  10 . The protective housing  10  is mounted on a support frame  12 . The radiation source  2  is installed on the upper area of the support frame  12 . The radiation source  2  is carried by a laser base  18  that is part of the laser carrier  15 . The laser carrier  15  is connected to the support frame  12 . On the laser base  18  there are several guide elements  20  with which a lateral guide of the radiation source  2  is achieved. The orientation of the radiation source  2  in the hand-guided marking system  1  is likewise simplified by the guide elements  20 . In the upper area of the hand-guided marking system  1  there is at least one handle element  24 . The hand-guided marking system  1  can be oriented with respect to the surface  101  of the workpiece  102  with at least one handle element  24 . 
     For supporting the handling of the hand-guided marking system  1 , an attachment  26  is further provided with which machine handling of the hand-guided marking system  1  is also enabled. The interplay of the handle element  24  and the attachment  26  makes possible an easy, simple, and bodily-protective positioning of the hand-guided marking system  1  with respect to the part of the surface  101  of the workpiece  102  on which the marking  100  is to be applied. 
     In the area of the protective housing  10  that is opposite the surface  101  of the workpiece  102 , a base plate  36  is provided. Between the base plate  36  and the laser base  18  there is a brace  17  that provides for additional mechanical stabilization of the hand-guided marking system  1 . In the embodiment shown here, the protective housing  10  has a rectangular shape. A safety initiator  39  is mounted on at least one outer wall  10 A of the protective housing  10 . With the safety initiator  39  it is possible to test and determine the correct mounting of the hand-guided marking system  1  on the workpiece  102  to be marked. The safety initiator  39  can be formed as an inductive proximity switch that monitors automatically. According to a preferred embodiment, two of these safety initiators  39  are provided in order to monitor the placement directly on the workpiece  102  to be marked. A safety initiator  39  here monitors that the hand-guided marking system  1  is located in a part receptacle (is placed on the bearing). Thus, the hand-guided marking system  1  or the radiation source  2  is placed on the workpiece  102  in a controlled way. By means of the controlled placement, it is possible for no light to be discharged from the radiation source  2  out of the interior of the protective housing  10 . As a function of the determination by the safety initiator  39 , a corresponding action thus can be triggered, in order to guarantee the safety conditions for the operation of the guided marking system  1 . 
       FIG. 2  shows a perspective view of the support frame  12  from a view from above. As already mentioned in the description to  FIG. 1 , the protective housing  10  is provided underneath the laser base  18 . The protective housing  10  also carries the camera  4 . In the laser base  18 , an opening  22  is formed into which at least one part of the optical system  25  of the radiation source  2  projects (see here  FIG. 4  and  FIG. 5 ). The protective housing  10  is closed by a base plate  36 . The at least one safety initiator  39  is mounted on the outer wall  10 A of the protective housing  10 . A drive  31  is also provided on the protective housing  10 . With this drive, a mirror  30  can be pivoted from a first position  30   1  into a second position  30   2  (see here  FIG. 4  and  FIG. 5 ). 
     In  FIG. 3 , the support frame  12  is shown in a perspective view from below. The base plate  36  has an opening  37 . The opening  37  is thus arranged opposite the area of the surface  101  of the workpiece  102  on which the marking  100  is to be applied. At least one lighting device  6  is provided on at least one inner wall  10 I of the protective housing  10 . By means of the lighting device  6  (see here  FIG. 4  and  FIG. 5 ), it is possible to light the marking  100  applied on the surface  101 , so that an image of the marking  100  of sufficient quality can be achieved with the camera  4 . This ultimately produces reliable readability of the marking  100 . 
       FIG. 4  shows a section view through the area of the hand-guided marking system  1  that essentially shows the protective housing  10 . The optical system  25  of the radiation source  2  here reaches, in part, through the opening  22  in the laser base  18 . The optical system  25  of the radiation source  2  thus defines an optical axis  16  along which the light of the radiation source  2  propagates. In the view shown in  FIG. 4 , the mirror  30  is in the first position  30   1 . The first position  30   1  means that the light provided by the radiation source  2  can propagate unimpaired along the optical axis  16  and reaches the surface  101  of the workpiece  102  through the opening  37  of the base plate  36 . 
     In  FIG. 5 , the situation is shown that the mirror  30  is pivoted into the second position  30   2 . If the mirror  30  is in the second position  30   2 , the light of the radiation source  2  that propagates along the optical axis  16  is blocked. With the lighting device  6  mounted on the inner wall  10 I of the protective housing  10 , the surface  101  of the workpiece  102  can be lighted in a suitable way, so that a qualitatively sufficient detection of the marking  100  on the surface  101  of the workpiece  102  is possible. The light emerging from the surface  101  of the workpiece  102  reaches through the opening  37  in the base plate  36  along the optical axis  32  of the camera  4  to the camera  4 . As can be seen from  FIGS. 4 and 5 , the camera  4  with a camera housing  4 G is mounted on the protective housing  10 . 
     Through the pivoting of the mirror  30  from the first position  30   1  (writing position of the radiation source  2 ) into the second position  30   2 , it is thus possible that the quality of the written marking  100  can be checked with the camera  4  after the writing of the marking  100  with the radiation source  2 . Here it is not necessary to change the hand-guided marking system  1  with respect to its position relative to the writing marking  100 . Through the base plate  36  it is guaranteed that no light of the radiation source  2  reaches the outside. Thus the safety or laser safety is guaranteed in the handling of the hand-guided marking system  1 . Furthermore, the base plate  36  guarantees that no light from the outside reaches into the interior of the protective housing  10 , which guarantees reliable readability of the marking  100  by means of the camera  4 , because interfering light from the outside cannot affect the reading. 
     LIST OF REFERENCE NUMBERS 
     
         
           1  Hand-guided marking system 
           2  Radiation source 
           4  Camera 
           4 G Camera housing 
           6  Lighting device 
           10  Protective housing 
           10 A Outer wall of the protective housing 
           10 I Inner wall of the protective housing 
           12  Support frame 
           14  Opening 
           15  Laser carrier 
           16  Optical axis of the radiation source 
           17  Brace 
           18  Laser base 
           20  Guide element 
           22  Opening 
           24  Handle element 
           25  Optical system 
           26  Attachment 
           30   1  First position 
           30   2  Second position 
           31  Drive 
           32  Optical axis of the camera 
           36  Base plate 
           37  Opening 
           39  Safety initiator 
           100  Marking 
           101  Surface 
           102  Workpiece
A hand-guided marking system ( 1) is disclosed, which is furnished with a radiation source ( 2) for applying a marking ( 100) to a surface ( 101) of a workpiece ( 102). A camera ( 4) and at least one illumination device ( 6) are used for recording a part of the surface ( 101) of the workpiece ( 102). A protective housing ( 10) is mounted on a carrier frame ( 12) and has an opening ( 14) in the protective housing ( 10) that is located opposite the surface ( 101) of the workpiece ( 102). The beam source ( 2) is positioned in the carrier frame ( 12) in such manner that an optical axis ( 16) of the beam source ( 2) passes through the opening of the protective housing ( 10).