making reference to the drawing views , and in particular to the block diagram of fig1 an apparatus according to the invention comprises a platform , indicated at pt and of a substantially known type . positioned below the platform pt , e . g . at the four corners thereof , are four transducers t 1 , t 2 , t 3 and t 4 , e . g . of the piezoelectric or strain gage types , being each adapted to provide : ( a ) for dynamic analysis purposes , that is where also of interest are the horizontal components , the three components f x , f y and f z of the force acting on each of them . ( b ) for static analysis purposes , with the subject motionless on the platform , only the vertical component acting on each of them . fz 1 , fz 2 , fz 3 and fz 4 = vertical components on the four transducers ; fx = fx 1 , fx 2 , fx 3 and fx 4 = sum of the four horizontal components in the direction x ; fy = fy 1 , fy 2 , fy 3 and fy 4 = sum of the four horizontal components in the direction y ; fz 1 , fz 2 , fz 3 and fz 4 = vertical components on the four transducers . use of other force platforms with different structures and transducers would involve corresponding changes in the numbers of the inputs and calculation algorithms for the instantaneous point of application of the force and of the three components fx , fy and fz of said force , while the remainder of the apparatus would be left substantially unaltered . as may be seen , the outputs from the four transducers t 1 , t 2 , t 3 and t 4 are input to an analog - to - digital converter , indicated at a / d in fig1 which as the skilled one may appreciate , should have a number of channels equal to the useful inputs which , as mentioned , would be six for case ( a ) and four for case ( b ). sampling is driven by a clock generator gs , at the frequency of 50 hz , which also drives the raster clocks for the tv camera and monitor m , thereby the mechanical event or rest reaction of the subject on the platform is sampled for each image . of course , the survey may be carried out , either simultaneously or successively , on the three planes x , y and z . in the former case , tv cameras should be used , one of which would be located below the plane of the platform pt , which in such a case is made of a transparent material . the apparatus of this invention includes , as a basic component thereof , a processor e , provided for receiving and processing the rest reaction data from the subject on the platform , through the converter a / d and under control by the clock generator gs . in particular , the processor is arranged to control a circuit block of tv representation of the rest reactions from the subject on the platform to reveal scoliotic affections of the subject . more particularly , the following representations are provided . assuming that the tv display is decomposed into i horizontal rows or lines , each of which identifies with i = 1 , 2 , 3 , . . . i . let ts be the raster or frame time ; then , the scanning time will be for each row : ## equ1 ## let each horizontal row or line be discretized into k k - th intervals ( pixels ), each with a duration time ## equ2 ## the entire tv display is identified by a i × k pixel matrix , where i is the number of rows and k the number of columns ( see fig3 ). x a = point of application of the vector is calculated as follows : let x 1p be the x coordinate of the midpoint between the first transducer pair ( t 1 and t 4 in fig2 ) and x 2p be the x coordinate of the midpoint between the second transducer pair ( t 2 and t 3 in fig2 ), then x 1p and x 2p will be found with a process of spatial calibration consisting of overlapping two moving pointers ( blank spots ) appearing on the screen on the preset line i ( p ) on the spatial markers marked directly on the platform . k ( x 1p ) and k ( x 2p ) are the pixels at the markers at x 1p and x 2p , respectively ; t ( x 1p ) and t ( x 2p ) are the times on the line i ( p ) whereat the pointers overlapping x 1p and x 2p , respectively , appear . the value k ( x a ) the thickness of the plate over the transducers being negligible is calculated as ( fig2 ). ## equ3 ## thus the pixel at the lower end of the vector will be given by i ( p ), k ( x a ). identifying the scale of vertical forces as n i =( number of rows per volt ) and that of the horizontal forces as n k ( number of k - th intervals per volt ), the upper vector end will be simple trigonometric calculations will then locate all the pixels forming the entire vector . for each image found or spotted by the raster clock a signal is formed which when added to the tv signal from the tv camera gives the vector overlapping the subject image . this signal will be null before the row counter reaches i ( z s ) and column counter reaches k ( x s ) ( upper end of the vector ). on this occurrence , the output signal has a pulse of duration δt and such an amplitude as to provide the blank on the monitor . that same pulse will be formed for all the rows with i ( z s )≦ i ≦ i ( p a ) at the k - th columns calculated as previously indicated . the same processing as previously described applies , except that x is replaced with y . ( a ) parametrized trajectory or path of the point of application according to the diagram of fig4 a . in this case , for each image a point is represented having coordinates x a and y a calculated as previously described ; on the plane z where the four fixed points forming the vertices of a rectangle represent the four transducers of the platform ( spatial reference ). ( b ) in each image , a vector beginning from the point ( x a , y a ) is represented with components f x and f y calculated as previously described . according to a further aspect of the invention , it is also possible to store in a dedicated memory the data relating to the force vectors , thus enabling : ( a ) reviewing of the mechanical phenomenon ( evolution with time of the force vectors on the various planes ) at a natural rate , slowed rate , in succesion with manual control ; ( b ) reviewing of the space - time representation of the evolution of the vectors on the various planes in a single image wherein all the vectors which followed one another during the phenomenon are stored . for clinic analysis , the subject is merely required to stay on the platform pt in front of the tv camera t after the doctor , to facilitate readout , has placed at some significant reference spots ( spinal processes at the level of the seventh cervical and first sacral of the apex of the bend on the sternum , on the iliac crests and great trocanthers ) simple self - adhesive markers . in particular , the survey is effected at five levels , namely : front frontal view ; rear frontal view ; right side view ; left side view ; rest plane . signal processings provide directly on the monitor m the subject image overlapped by the vertical line conducted through the barycenter ( vb ). for the analysis , the operator will position a moving pointer , which appears on the screen , on the above - specified reference points . the apparatus will provide a series of numbers which quantify the following magnitudes : misalignment of the spine relatively to vb at the level of the seventh cervical ( vcc ); misalignment of the spine relatively to vb at the sacral level ( dcs ); also obtained for each of the five levels considered is the photography of the image on a monitor . in fact , misalignment of cv , pelvic asymmetry , and pelvis rotation are characters already regarded as of import to the diagnosis and prognosis of idiopathic scoliosis , even though the difficulty and inaccuracy with which they are currently spotted has always made them difficult to utilize clinically . they are usually spotted or detected by manually processing the radiographic plates , without significant spatial or postural references , or by means of direct measurements on the patient which are of necessity approximative . the ac , although regarded as important in the detection of the disease , cannot be spotted on a clinic basis . in particular , as mentioned hereinabove , while the radiographic display retains unreplaceable information as relates to the structure of the rachis ( serious cases and pre - operatory investigation ), the survey provided by the apparatus according to the invention is to be regarded as complementary to and substitutive of radiography . to evaluate the effectiveness of the survey performed with the apparatus of this invention , a first trial prototype has been used as formed by assembling available devices and simply optically mixing the tv displays to produce preliminary surveys on a sample group of scoliotic subjects ( 20 subjects ). tests carried out have unequivocably evidenced the interest of the data to be derived for diagnoses , documentation and monitoring of scoliosis . in particular , the possibility of quantifying the following has been ascertained : variation of said parameters in different scoliotic subjects and during treatment , e . g . with corsets . it may be appreciated from the foregoing that the apparatus according to the invention fully achieves its objects . in particular , an apparatus has been provided which permits , through a non - invasive examination , easily carried out in clinic practice , documenting of postural vices and the assessment of the loads on the various articulations , e . g . of an athlete while practicing a sport . the results are obtained by means of images and numbers of direct clinic significance , as already usually considered in clinic practice . while the invention has been described with reference to a presently preferred embodiment thereof , it should be born in mind that it is susceptible to many changes and modifications without departing from the scope of the inventive concept as defined , in particular , in the appended claims .
the apparatus comprises a platform for supporting a patient to be examined and providing at least one component of the force exerted thereon by the patient , a tv camera so positioned as to pick up the image of the patient on the platform and cooperating with a monitor for displaying the picked up image in the form of a vectorial representation under the control of image processing circuitry and of a processor unit .