Abstract:
A pair of laser distance sensors are arranged to impinge a respective laser beam on a respective one of a pair of surfaces on a reference target installed on a car door to determine the extent of misalignment of a door latch and striker by determining the extent of any vertical door movement induced by such misalignment. The use of oppositely inclined surfaces eliminates the effect of small mispositioning of the reference target surfaces and the laser distance sensors. A side by side arrangement of the laser distance sensors can also be used to determine the door closing speed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional patent application No. 61/300,483, filed on Feb. 2, 2010, incorporated by reference herein. U.S. patent application Ser. No. 12/971,009 filed on Dec. 17, 2010 is also incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     In automobile production it is usual to the carry out inspections of car doors to insure proper operation and to enable adjustments or repairs to be made. These inspections desirably should be able to be carried out quickly as well as accurately due to time constraints in the production environment. 
     One such inspection is of proper door closing which requires good alignment of the striker and latch components in order to have the desired closing characteristics. The door closing speed necessary to operate the latch mechanism is another such inspection and an arrangement for determining this is described in copending U.S. patent application Ser. No. 12/971,009 referenced above. 
     Some equipment for inspections of this type require a precision set up of sensors and targets on the car which is time consuming to properly align and leads to errors if the necessary alignment is not accomplished during set up. 
     Such inspections should not require disassembly of the involved door parts. 
     It is an object of the present invention to provide an arrangement and method for measuring any misalignment between an automobile door striker and latch which can be carried out rapidly including the time necessary for set up and removal of the test equipment. 
     SUMMARY OF THE INVENTION 
     The above recited object and other objects of the present invention which will be understood upon a reading of the following specification and claims are achieved by an arrangement and method including dual laser distance sensors and a separate reference target which is attached to the door. 
     The reference target has a pair of surfaces thereon preferably oppositely inclined from the vertical, and a laser beam from each laser distance sensor is aimed at a respective surface to impinge a laser beam thereon as the door moves past the sensors to a closed fully latched condition. The points of impingement on the surfaces shift in a vertical direction if a misalignment exists and due to the surface inclination, the distance from the respective laser sensor changes correspondingly. 
     That is, if the latch and striker are misaligned, the door moves slightly vertically as the striker moves into the latch opening, and the extent of vertical movement is determined from the change in distance to the points of impingement in providing a measure of the extent of misalignment. 
     The laser distance sensors generate signals corresponding to the extent of vertical movement by detecting the change in distance to the points of impingement of the laser beams on the respective surfaces of the respective target surfaces as the reference target and laser sensor relatively shift in position along the vertical axis. The corresponding display and/or recording of these signals thus provides data corresponding to the degree of misalignment for quality control purposes and/or the making of corrective adjustments to the door latch mechanism. 
     The change in distance to impingement points on the respective target surfaces preferably varies inversely so that misalignments of the target and laser sensor are compensated for to minimize the degree of precision required in aligning the target and the dual laser sensor. 
     The laser distance sensors can be arranged in vertically stacked or in a side by side relationship. 
     With a side by side arrangement, the dual laser sensor unit can also measure the door closing speed by detecting the movement of the door edge successively past each laser sensor and measuring the time elapsed as the door edge moves past the two laser sensors successively. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is pictorial fragmentary view of an auto door and adjacent body structure showing the door striker and latch 
         FIGS. 2A and 2B  are diagrammatic depictions of the movement together of the striker and latch in the aligned and misaligned conditions respectively. 
         FIG. 3  is a pictorial fragmentary view of an auto door and adjacent body structure with a reference target installed on the door outer surface and a dual laser distance sensor unit held to the adjacent body surface. 
         FIG. 4  is an elevational diagrammatic view of the reference target and dual laser distance sensor unit showing the relationship of the laser beams and respective surfaces on the target. 
         FIG. 5  is a top diagrammatic view of the reference target and dual laser distance sensor unit shown in  FIG. 4 . 
         FIG. 6  is a diagrammatic representation of the reference target and sensor unit with orthogonal axes of movement indicated thereon. 
         FIG. 7  is a plot of the relative vertical positions of the reference target when passing the sensors the striker and latch properly aligned. 
         FIGS. 7A and 7B  are plots of each laser distance sensor readings during closing door movement with the striker and latch aligned. 
         FIG. 8  is a plot of vertical positions versus horizontal positions of the reference target with a misaligned striker and latch. 
         FIGS. 8A and 8B  are plots of respective laser distance sensor readings during door closing motion with a misaligned striker and latch and a correctly aligned reference target as indicated in  FIG. 6 . 
         FIG. 9  is an elevational diagram of the relative position of a reference target which is mispositioned slightly by being rotated about a transverse axis. 
         FIG. 10  is a plot of the vertical position of the reference target versus the horizontal position during a door closing cycle with the striker and latch misaligned and the reference target mispositioned in the manner indicated in  FIG. 9 . 
         FIGS. 10A and 10B  are plots of the respective dual laser distance sensor unit readings in the reference target condition shown in  FIG. 10  and with a misaligned striker and latch. 
         FIG. 11  is an elevational diagrammatic view of a reference target and dual laser distance sensor unit with the reference target rotated out of an aligned position. 
         FIG. 12  is a plot showing the relationship between the relative vertical position of the reference target and dual laser distance sensor unit as the reference target and sensor unit move past each other if the door closes when the striker and latch are misaligned and the reference target is rotated about a vertical axis from an aligned position. 
         FIGS. 12A and 12B  are plots of the distance to the respective points of impingements of each laser sensor beam on the reference target with the conditions represented in  FIGS. 11 and 12 . 
         FIG. 13  is a pictorial view of an aligned modified reference target and a second embodiment of a dual laser sensor unit in which the dual distance laser sensors are positioned side by side rather than vertically stacked. 
         FIG. 14  is an enlarged top view of the reference target and dual laser distance sensor unit shown in  FIG. 13  installed on an auto door and adjacent body, with a diagrammatic representation of the major components of the dual laser sensor unit. 
         FIG. 15A  is a top view of the installed reference target and dual laser sensor unit as shown in  FIGS. 13 and 14  in which the door closing speed is being determined by imaging the door edge as the door approaches the closed position. 
         FIG. 15B  is a top view of the reference target successively passing the laser distance sensors to determine the extent of any misalignment of the striker and latch as the door is being fully closed. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims. 
     Referring to the drawings,  FIG. 1  shows a typical automobile door  10 , having a latch component  12  on the end, and a striker  14  fixed to the adjacent body structure  16 . 
     The latch  12  has a wedge shaped opening  16  which receives the striker  14  when the door closes, causing a secure capture of the striker  14  when the door  10  is fully closed in the well known manner. 
       FIGS. 2A and 2B  depict the striker  14  moving into the latch opening  16  on the door closes. The striker  14  should be centered on the opening  16  as shown in  FIG. 2A . If the striker  14  is misaligned as shown in  FIG. 2B , the door  10  is cammed up (or down) as it closes due to the wedge shape of the opening  16 . 
     Excessive misalignment requires an excessive speed of door closing to latch the striker  14 , and thus the door operation is inspected during production to determine if excessive misalignment exist. Suitable adjustments can correct the problems, or component replacement may be necessary. 
     The production process requires that such inspection be carried out quickly and reliably, and disassembly of components cannot be required. Similarly the set up and removal of test componenting must both be able to be carried out quickly. 
       FIG. 3  shows a basic test set up according to the present invention, which relies on the fact that the degree of misalignment corresponds to the extent of vertical movement of the door as it comes to a fully closed state to the upper sensor  28 A as seen in  FIG. 10A . 
     The arrangement includes a reference target  20  detachably affixed to the door  10  adjacent the far side remote from the hinges as by a magnetic or vacuum holder (not shown). 
     The reference target comprises a body  22  which has a triangular in section shape, with oppositely inclined from the vertical planar surfaces  24 A,  24 B ( FIG. 4 ) facing a dual laser sensor unit  26 . 
     The dual laser sensor unit  26  comprises a pair of laser distance sensors  28 A,  28 B stacked vertically. 
     The unit  26  is of a type described in copending, U.S. pending application Ser. No. 12/971,009 referenced above. Each laser distance sensor  28 A,  28 B includes a laser beam source which directs a beam at a respective surface  28 A,  28 B, and a light sensitive element such as a ced equipped with a focusing optic receiving reflected light from the respective surface  28 A,  28 B and generating corresponding signals. These signals are processed in a signal processor to calculate the distance d by the well known laser triangulation process. Such devices are well known and commercially readily available. 
     In the present described arrangement, the sensors  28 A,  28 B are stacked vertically one atop the other so as to each be aligned with a respective surface  24 A,  24 B of the reference target  20 . 
     As the door swings closed, the laser beams from the sensors  28 A,  28 B move substantially horizontally along the y axis across the inclined surfaces  24 A,  24 B if the latch  12  and striker  14  are aligned. 
     Further the vertical location of the reference target  20  remains constant relative the sensor unit  26  as indicated in  FIG. 7 . 
     Furthermore, the distance d from each sensor  28 A,  28 B to the point of impingement remains constant as indicated in  FIG. 7A ,  7 B. 
     However, if the latch  12  and striker  14  move relative each other in a vertical direction due to a misalignment therebetween, the vertical location of the reference target  20  relative the sensor unit  26  will change, i.e. rise or drop relative the sensor unit  26  depending on the direction of misalignment, after the striker  14  engages one of the surfaces defining latch opening  16 . This is indicated in  FIG. 8 . 
     Due to the opposite vertical inclination of the surfaces  24 A,  24 B, the distances between sensor  28 A and the opposite points on the surface  24 A will increase since the points of impingement will be at a point on the surface  24 A further above the center, and between sensor  28 B and surface  24 B will be decrease since the points of impingement will be closer to the center of the reference target  20 , as seen in  FIGS. 8A and 8B . 
     The use of dual sensors  28 A,  28 B compensates for minor mispositioning of the reference target  20  relative the sensor unit  26  to make set up of the reference target  20  quicker and easier. 
       FIG. 9  shows the reference target  20  tilted towards the sensor unit  26 . If the reference target  20  drops (or rises) relative the sensor unit  26  as the striker  14  engages the latch  12  due to misalignment of the striker  14  and latch opening  16 , the rotated position of the reference target  20  affects the distances sensed by the sensors  28 A,  28 B. Since the upper surface  24 A becomes more steeply inclined from the vertical as seen in  FIG. 9 , a given increment of vertical motion produces a reduced distance change from the surface  24 A. 
     On the other hand, the change in distance from surface  24 B to sensor  28 B is greater due to the shallower inclination from the vertical of surface  24 B. However, the calculated drop distance and extent of misalignment will remain the same and can be computed from the A and B distance changes. 
       FIG. 11  shows the reference target  20  rotated about a vertical axis to be skewed with the sensor unit  26 . As the door  10  swings past the sensor unit  26 , the sensed distances to the points of impingement on the surfaces  24 A,  24 B will change continuously even prior to the engagement of the striker  14  since the point of impingement of the sensor beams will be gradually ascending the surfaces  24 A and  24 B, causing an increasing distance A and decreasing distance B to the respective points of impingement on the surfaces  24 A,  24 B as seen in  FIGS. 12A and 12B . However, after the inflection point is reached by engagement of a misaligned latch  16  and striker  14 , the distance change due to the vertical door motion can still be computed by summing the A and B change in distance to determine the degree of misalignment. 
     The laser distance sensors can be located side by side rather than stacked as in the embodiment described above. This has the advantage of allowing the door closing speed to also be determined by the same sensor. 
       FIG. 13  shows the change in configuration of the reference target  30  when using side by side sensors  32 A,  32 B in a sensor unit  34 . 
     The reference target  30  is comprised of side by side surfaces  36 A,  36 B each inclined to the vertical but in opposite directions. The two laser sensor  32 A,  32 B are sufficiently aligned with a respective surface  36 A,  36 B so as to direct a laser beam to impinge on a respective surface. 
     The sensor unit  34  may optionally be supported on a separate stand  38  positioned alongside the auto body  18  as shown. 
       FIG. 14  shows further details of the sensor unit  34 , with each sensor  32 A,  32 B including a laser source  40 A,  40 B directing a laser beam at a respective surface  36 A,  36 B. 
     The reflections are viewed through optics  42 A,  42 B and the image detected by CCD or COM detectors  44 A,  44 B. 
     The signals are processed in a signal processor  46  and the results sent to a display  48  or to a central computer, memory, etc., for recording and use or reference. 
     Thus, the change in distances between the sensors  32 A,  32 B and the surfaces  36 A,  36 B caused by vertical motion allows computation of the degree of misalignment of the striker  14  and latch  12  in the above embodiment. 
     The side by side arrangement of the laser sensors  32 A,  32 B allow the speed of the door  10  to also be determined as shown in  FIGS. 15A ,  15 B. 
     As the door  10  swings shut, the time for a door edge feature  50  to move successively past the two sensors  32 A,  32 B can be determined and from that elapsed time, the speed of closing of the door  10  can be computed as described in the copending application Ser. No. 12/971,009 referenced above. 
     This can be numerically displayed in display  48  and/or electronically recorded for later. Thus, both tests can be carried out by the same arrangement.