Abstract:
A marking device is disclosed which efficiently reduces damage affecting the gimbal mechanism even when such is used under sever conditions and is dropped from a high position. A marking device has a support mounted inside a housing, a light source unit holder swingably suspended by the support through a gimbal mechanism, and a light source unit mounted on the light source unit holder so as to diffuse a light flux only in a single direction to radiate a line of light. The support is coupled with said housing 1 through dampers with upper portion and lower portion formed of an impact absorber, and when outside impact is applied, the damper absorbs impact energy to prevent the impact force from being transmitting to the support.

Description:
BACKGROUND OF THE INVENTION  
   1. Field of the Invention 
   The present invention relates to a marking device configured for irradiating a vertical or horizontal line laser to a surface of the subject to be irradiated by diffusing light flux only in a single direction from a light source such as semiconductor laser, particularly related to the impact absorption structure thereof. 
   2. Related Background of the Invention 
   In a construction site, used is an optical marking device irradiating a vertical line light or a horizontal line light which is a criterion of a vertical degree and a horizontal degree of pillars and walls. Most of the light sources of the optical marking device are semiconductor lasers and are generally referred to as a laser marking device. The laser marking device suspends a mechanism referred to as a gimbal mechanism or a gyro mechanism (hereinafter referred to as “gimbal mechanism”) in a perpendicular orientation so as to always maintain a vertical position and supports a light source unit including the semiconductor laser with the above mentioned light source unit holder. The light source unit includes a semiconductor laser as a light source, a collimating lens converting dispersing light radiated from the semiconductor laser into a parallel light flux, and a rod lens dispersing the parallel flux in a single direction. The parallel light flux enters into the rod lens from a direction perpendicular to a center axis thereof and is diffused in a fan shape only in a direction perpendicular to the above mentioned center axis by refraction by the rod lens. This diffusion light is irradiated to walls, ceilings, and floors of the building so as to draw straight lines by radiated light. Then a vertical line light can be irradiated by mounting the above mentioned light source unit on the above mentioned unit holder in such way that the center axis of the rod lens is horizontal. In addition a horizontal line light can be irradiated by mounting the above mentioned light source unit on the above mentioned unit holder in such way that the center axis of the rode lens is horizontal. Such is a fundamental principle of the laser marking device. 
   In the laser marking device, the light source unit holder supporting the light source unit is swingably supported by the gimbal mechanism. The laser marking device is required to accurately irradiate light of a vertical or horizontal direction line. For that reason, the gimbal mechanism desirably has a low friction resistance and the light source holder is desired to be maintained in a predetermined vertical direction position. Therefore, generally a bearing portion of the gimbal mechanism mainly comprises a ball bearing and an axis rotatably supported thereby. However, since potentially the lowest friction resistance is selected for the ball bearing employed in the gimbal mechanism of the laser marking device, a problem of impact resistance exists. Therefore, even in the case that the laser marking device is erroneously dropped down during use, the bearing portion is damaged adversely affected due to impact resistance to increase the friction resistance such that the light source unit holder cannot hold the predetermined position, which thus causes a problem of deteriorated accuracy of the irradiated line light. 
   In view of the foregoing, there has been proposed a laser marking device comprising a first support for swingably journaling a laser beam irradiating device with a first support shaft, a second support for swingably journaling the first support with a second support shaft perpendicular to the first support shaft, and a supporting member provided with a holding portion for holding the second support, wherein the second support is held on the above mentioned holding portion in such way that interference bodies are interposed respectively on both sides along longitudinal, lateral and vertical directions of the second support (ref. to, for example, Patent Reference  1 , discussed below). The above mentioned “laser beam irradiation device” is the member corresponding to “light source unit holder” mentioned above. The first support shaft, the second support shaft and the second support comprise a gimbal mechanism. The above impact absorber reduces the impact otherwise applied to the above mentioned holding portion to transmit to the light source unit holder which is swingably journaled by the above mentioned gimbal mechanism, thereby reducing the damage to the gimbal mechanism. 
   The invention of the Patent Reference  1  is effective in protecting the gimbal mechanism when the laser marking device is dropped. However, the configuration of the above mentioned impact absorber of the Patent Reference  1  invention is required to entirely cover the exterior surface, top and bottom surfaces, and both side surfaces of the second support, which therefore increases the area and a volume of the impact absorber and thus increases the cost of the impact absorber. In addition, the volume of the laser marking device also increases due to the presence of the impact absorber. Moreover, there are many which are interfered with, such as the gimbal mechanism, the light source unit holder as well as the second support, for which impact absorbing effect should be improved. These factors also increase the volume of impact absorber. 
   Patent Reference 1 referred to above is Japanese Patent 2004-301756 A. 
   The present inventor proposes a marking device in which an impact absorber held by a support covers periphery of both ends of a shaft having a gimbal mechanism and above mentioned shaft is supported by the support through this impact absorber. That is an invention related to Japanese Patent Application 2005-64234. 
   According to the invention related to the above mentioned application, impact absorption effect is provided as expected. However, assuming that it is used under the severe conditions in dropping from a high location e.g. more than 1 m, it is found that even the invention related to the above mentioned application can not obtain a sufficient impact absorption effect. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a marking device which effectively reduces damage to the gimbal mechanism even when it is used under sever conditions such as being dropped from a high location, and which is durable for subsequently continuous usage. 
   A marking device according to the present invention comprises a support mounted inside a housing, a light source unit holder swingably suspended by this support through a gimbal mechanism, and a light source unit mounted on this light source unit holder so as to diffuse a light flux only in a single direction to radiate a line of light, wherein the above mentioned support is coupled with the above mentioned housing through a damper with an upper portion and lower portion formed of an impact absorber, such that when an outside impact is applied the above mentioned damper absorbs impact energy so as to prevent the impact from being transmitted to the above mentioned support. 
   The damper has a hole provided therein in an axial direction and has a small diameter portion in a middle portion in the axial direction, the above mentioned hole being penetrated at one end by a mounting shaft coupled with the housing or the support and the damper is coupled with the support, wherein the above mentioned small diameter portion is fit in with a portion substantially integrated with the support or the housing so that an upper portion and an lower portion of the support are coupled with the housing through the dampers. 
   The support is configured such that the lower portion is supported by the housing through the damper and the upper portion is suspended by the housing through the damper. Therefore, the support is raised from the housing by interference of the damper. When the marking device falls down or is dropped, most of the impact force applied to the housing is absorbed by the dampers in the upper portion and the lower portion of the support so that the impact force is prevented from being transmitted to the support. For this reason, the impact force transmitted from the support to the gimbal mechanism is reduced and the impact force applied to the support portion of the shaft constituting the gimbal mechanism is also reduced, such that any damage affecting the gimbal mechanism is dramatically reduced. Even if relatively large impact force is applied thereto, the device can be continuously used without readjustment and repairs. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side cross sectional view of a marking device according to one embodiment of the invention; 
       FIG. 2  is a front cross sectional view of the marking device; 
       FIG. 3  is a schematic top plan view showing an arrangement relating to dampers in the upper and lower portions in the embodiment; 
       FIG. 4  is a front view of the damper; 
       FIG. 5(   b ) is a cross sectional view of the mounting member; 
       FIG. 6(   a ) is a front elevational view of a sleeve; 
       FIG. 6(   c ) is a cross sectional view of the sleeve. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   An embodiment of the marking device related to the present invention will now be described with reference to drawings. 
   In  FIGS. 1 to 3 , a cylindrical housing  1  has a top plate  11  and a bottom plate  12 , and a lower surface of the bottom plate  12  is mounted on a tripod, which is not shown, so as to be installed with the tripod in a vertically standing posture. In the housing  1  mounted is a support  2  for swingably supporting a light source unit holder  4 . The present invention features a structure for mounting this support  2 . The support  2  is coupled with the above mentioned housing  1  through dampers  7  and  8  formed of impact absorber at upper and lower portions. The upper dampers  7  are formed as a pair and each of the dampers  7  is mounted on the lower surface of the housing  1  with a screw  17 . The lower dampers  8  are formed as a pair and are held by a diskform mounting member  10  horizontally fixed to inner periphery of the housing  1  in the vicinity of the bottom plate  12  of the housing  1 . As shown in  FIG. 3 , assuming that a line connecting the centers of the lower dampers is in an X-axis direction line and a line connecting centers of the upper dampers is in a Y-axis direction line, the above mentioned X-axis direction line and Y-axis direction line cross at right angles with each other with respect to the center axis of the housing  1 . 
   Each of the above mentioned dampers  7  and  8  has the same structure and  FIG. 4  shows a structure of the damper  7  representing these dampers. In  FIG. 4 , the damper  7  is entirely formed of an impact absorber and the damper  7  has an axial direction hole  71 , a small diameter portion  74  around an outer periphery of axially center portion, and large diameter portions  72 ,  73  sandwiching the small diameter portion  74 . The impact absorber forming the damper  7  has a characteristic such that an applied kinetic energy is absorbed by converting said energy into thermo energy and is required to have no repulsion force or a low repulsion force. There is “low repulsive rubber” as a material to meet the requirement and spongy low repulsive rubber is used in this embodiment. The above mentioned hole  71  is penetrated by a mounting shaft and one end of the mounting shaft is coupled with the above mentioned housing  1  or the above mentioned support  2 , so that the housing  1  is coupled with the support  2  with the above mentioned damper  7  being interposed therebetween. Since the structures in which the housing  1  and the support  2  are coupled with the damper interposed are different between the upper portion and the lower portion, the structure of the coupling of the housing  1  and the support  2  will be individually described next with respect to the upper portion and the lower portion. 
   In  FIGS. 1 and 2 , an extension mounting member  9  is extended to the upper end of the support  2  by appropriate means such as a screw cramp. In the extension mounting member  9 , an upper end portion and a lower end portion of a vertical plate are bent at a right angle in a form of a lateral U shape. In addition, a piece bent at the lower end of the mounting member  9  is coupled with the upper end of the support  2 . A piece  91  bent at the upper end of the extension mounting member  9  is formed with two arc cuts, on each of which the small diameter portion  74  of the above-mentioned damper  7  is fit, thereby mounting the damper  7  on the extension mounting member  9  substantially integrated with the support  2 . The hole  71  of each damper  7  is inserted with a sleeve  80  shown in  FIG. 6 . In  FIG. 6 , the sleeve  80  includes a cylindrical body portion fit in the center hole of the damper  7 , and a flange portion  81  integrally continued with one end of the body portion. The center hole  71  of the above mentioned damper  7  is fit with the body portion of the sleeve  80 , and the flange portion  81  of the sleeve  80  is adjacent the upper end face of the damper  7 . A screw  17  penetrating the top plate  11  of the housing  1  passes through the center hole of the body portion of the sleeve  80  from the upper side, and each screw  17  projected from the lower end face of each damper  7  is fit with a washer  76  and further screwed with a nut. Thus each damper  7  is mounted on the top plate  11  of the housing  1  and the upper portion of the support  2  is coupled with the lower face side of the top plate  11  through each damper  7 . 
     FIG. 5  shows the mounting member  10  fixed to the lower portion of the housing  1 . As shown in  FIG. 5 , the mounting member  10  is formed out of a plane plate material into a ring shape, is provided with four mounting holes  101  circumferentially equally spaced at periphery of the mounting member  10 , and has two round holes  102  for mounting the damper  8 . The mounting member  10  also has a relatively big round hole  103  at the center of thereof. The mounting member  10  is sandwiched at the lower portion of the housing  1  and a screw  13  penetrating the above mentioned mounting hole  101  from the lower portion of the housing  1  is tightened and fixed to the body of the housing  1 . The above mentioned two round hole  102  of the mounting member  10  is fit with the small diameter portion each of the dampers  8 , thereby mounting the damper  8  on the mounting member  10  substantially integrated with the support  2 . The center hole of each damper  8  is inserted with the body portion of the above mentioned sleeve  80  from the upper side, and the flange portion  81  of each sleeve  80  is adjacent to the upper end face of the damper  8 . The screw  15  is screwed in the center hole of each sleeve  80  from the lower side, and the upper end portion of each screw  15  projected from the upper end face of each sleeve  80  is screwed into the bottom plate  26  of the support  2 . A washer  86  is interposed between the top portion of each screw  15  and the bottom face of the damper  8  present at such location. Thus each damper  8  is coupled with the mounting member  10  substantially integrated with the housing  1 , and the lower portion of the support  2  is coupled with the mounting member  10  substantially integrated with the housing  1  through each damper  8 . 
   Thus, the upper portion of the support  2  is coupled with the top plate of the housing  1  through dampers  7  in such mode such that the top plate of the housing I suspend the support  2 , and the lower portion of the support  2  is coupled with the lower portion of the housing  1  through the damper  8  and the mounting member  10  in such mode that the support  2  is supported upward from the lower portion of the housing  1 . When an impact is applied in a vertical direction in a standing posture as shown in  FIGS. 1 and 2 , the support  2  tends to cause relative movement to the housing  1  in a vertical direction. At this time, the large diameter portions  72 ,  73  of both ends of the damper  8  in vertical direction are deformed and the large diameter portions  82 ,  83  of both ends of the damper  7  in vertical direction are deformed, so that each damper  7 ,  8  converts an impact force into thermal energy to reduce the impact force transmitted to the support  2 . When the impact force is laterally applied due to the external factor such as fall of the housing  1  in  FIGS. 1 and 2 , the support  2  tends to cause relative movement to the housing  1  in a vertical direction. In this case, the small diameter portion  74  of each upper damper  7  is pushed by the bent piece  91  of the extension mounting member  9  integrated with the support  2 , and the small diameter portion of each lower damper  8  is pushed by the mounting member  10  integrated with the housing  1 . Since the small diameter portion of each damper  7 ,  8  is also formed of absorber material such as low repulsive rubber, the impact force to be transmitted to the support  2  is converted into thermal energy due to deformation of the small diameter portion of each damper  7  and  8  to reduce the impact force transmitted to the support  2 . 
   The center hole of each damper  7 ,  8  is fitted with the sleeve  80  and each damper  7 ,  8  can deform along a circumference of the sleeve  80 , thereby each damper  7 ,  8  is deformed smoothly and the damping function is efficiently performed. 
   The dampers  7 ,  8  each may be entirely and integrally formed of an impact absorber made of the same material. Since the impact force to be reduced is different in direction between the large diameter portion and the small diameter portion, different materials may be used so that the impact force is efficiently reduced based on the direction of the impact force to be reduced. In the case of different materials between the large diameter portion and the small diameter portion, different materials are arranged along the axial direction and adhered. 
   Next, the configuration of the light source unit holder  4  supported by the above mentioned support  2  and the gimbal mechanism  3  swingably suspending this light source unit holder  4  will be described. In  FIGS. 1 and 2 , a pair of bearing holders  21 ,  21  are integrally formed in the upper portion of the support  2 . A pair of the bearing holders  21 ,  21  has a cylindrical shape with bottom and open ends are opposing with each other. And the damper  22 ,  22  having cylindrical shape with bottom are embedded inside the bearing holders  21 ,  21 . Each damper  22 ,  22  may be formed of the material having absorption function, such as the impact absorber made of low repulsive rubber as well as in the above mentioned damper  7 ,  8 . Bearing  23 ,  23  such as a ball bearing is fit in the bearing holder  21 ,  21  through each damper  22 ,  22 , and a shaft  25  is rotatably supported by the bearing  23 ,  23 . 
   An intermediate swinging frame  40  is swingably supported around the above mentioned shaft  25 . The intermediate swinging frame  40  is integrally formed with a pair of bearing holders  45 ,  45 . Each of the bearing holders  45 ,  45  has a cylindrical shape with bottom and open ends are opposing to each other. The dampers  44 ,  44  each have a cylindrical shape which is embedded inside each bearing holder  45 ,  45 . The impact absorber made of low repulsive rubber may be used as a material of each damper  44 ,  44  similarly as for the above mentioned damper  7 ,  8 . Bearings  43 ,  43  such as a ball bearing are fitted in the bearing holder  45 ,  45  through each damper  44 ,  44 , and a shaft  41  is rotatably supported by the bearings  43 ,  43 . The shaft  41  is supported on the upper side of the above mentioned shaft  25  in a direction perpendicular to the shaft  25 . The shaft  41  suspends the light source unit holder  4  which is swingable around the shaft  41 . The above mentioned bearing  23 ,  43 , the shaft  25 ,  41 , and the middle swinging frame  40  constitutes the gimbal mechanism  3 , through which the support  2  swingably suspends the light source unit holder  4 . The above mentioned shaft  25  penetrates the light source unit holder  4  and a relief hole  46  for the shaft  25  is formed in the light source unit holder  4  so that the shaft  25  does not obstruct the light source unit holder  4  swinging around the shaft  41 . 
   A light source unit  5  is mounted on the upper end portion of the light source unit holder  4  and a light source unit  6  is mounted in the middle portion in vertical direction and under the above mentioned shaft  25 . The light source unit  5  irradiates a vertical line of light and includes a unit case  51  and a rod lens  52  mounted on the upper end of the unit case  51 . A semiconductor laser is mounted as a light source in the unit case  51  and a collimating lens for collimating diffusion light radiated from the semiconductor into parallel light flux is mounted. In the configuration, the above mentioned parallel light flux enters in a direction perpendicular to the center axis line with respect to the rod lens  52 , and the rod lens  52  diffuses and outputs the parallel light flux only in a direction perpendicular to the center axis line. When the light source unit holder  4  is in the predetermined hanging position, the rod lens  52  of the light source unit  5  is in a horizontal direction and designed to irradiate the vertical light line. The light source unit  5  is configured to be mounted pointing obliquely upwards on the light source unit holder  4  to irradiate the line light from walls to ceilings of the building for example. 
   The other light source unit  6  irradiates a horizontal line of light and includes a unit case  61  and a rod lens  62  mounted to the end of this unit case  61 . The unit case  61  is provided with semiconductor laser as a light source and a collimating lens for collimating diffused light radiated from the semiconductor laser into parallel light flux. In this configuration, the above mentioned parallel light flux enters in a direction parallel to the center axis line with respect to the rod lens  62  and the rod lens  62  diffuses and outputs the parallel light flux in a direction perpendicular to the center axis line. When the light source unit holder  4  is in the predetermined hanging position, the light source unit  6  is mounted pointing in a horizontal direction and the rod lens  62  of the light source unit  6  is oriented in vertical direction to irradiate horizontal line light. 
   The light source unit holder  4  is provided with a braking plate  42  in the lower end portion thereof. The braking plate  42  is to brake swinging of the light source unit holder  4  due to magnetic action, and is formed in such way that a swinging direction with the above mentioned shaft  25  as a center forms an arc following a swinging trait and formed to extend to both sides of the light source unit holder  4 . A swinging direction of the above mentioned braking plate  42  with the above mentioned shaft as a center is formed in an arc following the swing trait. The material of the light source unit holder  4  is not particularly specified but at least a portion of the braking plate  42  is formed of conductive material. The upper face of the bottom plate  26  of the above mentioned support  2  is fixed with the appropriate number of magnets  50  appropriately spaced with respect to the above mentioned braking plate  42 . Each magnet  50  is arranged through the appropriate yoke in such way that the magnet  50  is declined to cope with the arc face of the braking plate  42  to correspond the above mentioned braking plate  42  with the arc face. The braking plate  42  is located within a magnetic field formed by respective magnets  50 . When the light source unit holder  4  is swung by the gimbal mechanism  3 , the braking plate  42  crosses the line of magnetic force of the magnetic field to generate eddy current to the braking plate  42 . With this eddy current, driving force (torque) is generated in a direction opposite to the swing direction of the light source unit holder  4 . Therefore, this driving force functions as a force to stop the swing of the light source unit holder  4 , and quickly stop the light source unit holder  4 . 
   Thus the configuration of the embodiment shown in the drawings is as described above. Next, the action and effect of the above mentioned embodiment will be described. It is assumed that the marking device is applied with exterior impact for some factors such as dropping or falling down. As mentioned above, with regard to the vertical impact force, the large diameter portions in the both ends in vertical direction of dampers  7 ,  8  in the upper portion and the lower portion are deformed, whereby the dampers  7 ,  8  converts impact force into thermal energy to reduce impact force transmitted from the housing  1  to the support  2 . With respect to horizontal impact force the small diameter portion of the dampers  7 ,  8  in the upper and the lower portion is pushed by a bent piece  91  of the extension mount member  9  and the deformation of each small diameter portion converts the impact force to reduce the impact force to be transmitted from the housing  1  to the support  2 . Since the support  2  is mounted in such way that the upper portion and the lower portion of the support  2  are raised from the housing  1  due to interference of the dampers  7  and  8 , the outside impact force is absorbed by respective dampers  7 ,  8 , thereby the impact force transmitted from the housing to the support  2  can be dramatically reduced. The impact force applied to the gimbal mechanism  3  supporting the support  2  can be also reduced, damage to the gimbal mechanism caused by the outside impact force can be reduced, and accuracy distortion caused by the impact force applied to the marking device can be dramatically reduced. Therefore, it is durable even for rough handling, can be continuously used without readjustment or repair even if relatively big impact force is applied, and chances of readjustment or repair can be reduced. 
   An object of the present invention can be achieved by coupling the upper portion and the lower portion of the support  2  with the housing  1  through dampers  7  and  8  made of impact absorber. In addition to this, the shafts  25  and  41  constituting the gimbal mechanism  3  are supported through the dampers  22  and  44  as in the embodiment in the drawing so that damage applied to the shafts  25  and  41  of the gimbal mechanism  3  caused by outside impact force can be further efficiently reduced. Distortion of the accuracy due to the impact force can be efficiently reduced and chances of readjustment and maintenance can be reduced. 
   The damage applied to the shafts  25  and  41  of the gimbal mechanism  3  includes deformation of the bearing supporting the shafts  25  and  41  as well as bending and deformation of the shafts  25  and  41 . When the shafts  25  and  41  of the gimbal mechanism  3  are subject to damage, the gimbal mechanism  3  does not operate smoothly and the light source unit holder  4  can not hold the predetermined hanging position, thereby causing uneven static positioning of the light source unit holder  4 . As a result, line light irradiated from the light source units  5  and  6  is not in vertical direction or horizontal direction. 
   With this respect, with the present invention, since damage of the shaft of the gimbal mechanism due to the impact force can be reduced further efficiently, distortion of degree of the vertical line light and the horizontal line light can be prevented even if relatively big impact force is applied. 
   Although two dampers are provided respectively with regard to dampers  7  and  8  in the upper portion and the lower portion in the embodiment in the drawing, the number of dampers in the upper and lower portions is arbitrary. For example, in the upper portion and the lower portion, a plurality of dampers may be arranged in one portion and a single damper may be arranged in the other portion. Further, three dampers may be arranged at least one portion and the dampers may be supported by support at three points. 
   As shown in the embodiment of the drawing, the upper portion and the lower portion each has a pair of dampers, and dampers are arranged in such way that a line connecting the centers of two dampers in the upper portion and a line connecting centers of two dampers in the lower portion are perpendicular with each other. Then the support is prevented from declining in one side and the support can be stably supported.