DE2517008A1 - DEVICE FOR DYNAMIC VISIBILITY OF THE DISTRIBUTION OF THE IMPRESSIONS OF THE SOLE - Google Patents

Description

MÜLLER-BORE · GROENlNG · DEUFEL · SCHÖN · HERTEL

PATENT LAWYERS
MUNICH · BRAUNSCHWEIG · COLOGNE

Dr. W. Müller-Bora · Braunschweig H. Groenlng, Dipl.-Ing. ■ Munich

A 3 4 - 2 Dr. P. Deufel. Dipl.-Chom. - Munich

Dr. A. Schön, Dlpl.-Chem. ■ Munich Werner Hertol. DIpl.-Phys. · Cologne

ANVAR

(AGENCE NATIONALE DE VALORIZATION DE LA RECHERCHE)

Device for dynamic visualization of the distribution of the contact pressure on the sole of the foot

The invention relates to a device for dynamic visualization the distribution of the contact pressure of the sole of the foot with a piezo-optical transducer, which is composed of elements is, which convert the supported pressure into light intensity, as well as with a device for a sequential Analysis of these elements for the display of an isobar image or a diagram showing lines of equal pressure.

The devices for examining the distribution of the bearing forces of the foot while running for the analysis of diseases of the musculoskeletal system and especially the feet are in two Divisible into groups. In one group, a sensor with a small number of transducers is connected to the foot. Each of the converters is in turn connected to a separate analysis path. The person or patient leaves on a tape, which runs opposite to the direction of movement of the person, so that the distance of the person to

Munich office: 8 München80 Sleberbtr. 4 P.O. Box 860720 Cable: Muebopat Munich Telex 5-22050,5-22659 Telephone (089) 471 079/29 3845

609848/0718

Analyzer remains essentially constant. Doing so simultaneously recorded the signals in each of the analysis routes. In the second group there is a sensor with a large number of elements represents the surface on which the foot comes to rest when running. The print information is through a sequential examination or scanning of the sensing elements obtained and processed so that they have a usable shape obtained, for example result in a sequence of images of isobars or lines of equal pressure. This second group of Devices gives a finer resolution of the position information at the expense of a multiplication of the sensing elements, whose individual positions are known through the order of the scanning sequence. Feelers have been made out of one soft band, the scattering inner surface of which is a matrix-shaped arrangement of pyramids, which with their Rest the tip on a transparent surface. The local pressure of the foot on the top of the ligament causes a Flattening or compressing the pyramids, the contact area of which increases with the pressure. When proper lighting is present, these contact areas form light areas on a darker background. You get one like that piezo-optical transducer, which is composed of a matrix of uniform elements, in which one after the other the scattered amount of light can be analyzed. The sequential scanning of this matrix requires an exact coincidence of the Raster or single image of the scan and the matrix, whereby either an adjustment in the direction and location of the Scanning raster or a correlation analysis of the scanning signal is necessary in order to form sequential information again, which correspond to the content of the information in the matrix. The two solutions thus lead to complex and costly ones Executions.

The object on which the invention is based is therefore to solve the problems of the spatial coincidence of the elements of the piezo-optical transducer and the sequential analysis information.

609848/0718

According to the invention, this object is now achieved with a device for dynamic visualization of the distribution of the contact pressure on the sole of the foot with a piezo-optical transducer, the is composed of elements that convert the supported pressure into luminosity, and with a device for a sequential analysis of the elements for a display in the form of an isobar diagram solved in that the Transducer is a flat plate that forms a network of parallel light strips or grooves, the width of which Stripes at any point is a direct function of the normal pressure on the plate at that point, and that an analyzer is provided with a scan for the lines and the individual image or the image frequency or the raster, wherein the line scan is orthogonal to the strips.

In this way the matrix of elements for the local printing information is obtained from the intersection of the network of strips of the converter and the line network of the scanning of the analyzer. So the consequence is that of the analyzer obtained information directly and without setting or control the information sequence coming from the matrix.

In a preferred embodiment of the invention, the converter has a transparent plate with parallel surfaces, which are illuminated by the edge at an angle of incidence which corresponds to the total reflection on these surfaces. The converter also has an elastic band with a light-scattering surface or a diffusion surface for the Light and is from a network or grid of sharp-edged V-shaped surface projections or protruding surface angles formed with the tape lying along the sharp edges on the plate. At the contact points of the diffusion surface of the tape and the transparent plate, the light trapped by total internal reflection in the plate is scattered so that the contact points are through the plate shine strongly. Squeezing the edges of the

509848/0718

Surface angles or projections under the contact pressure leads to a local widening of the strips of the network or grid formed by the edges.

The plate is preferably arranged horizontally. The analyzer has a television camera and a mirror, which is inclined for the side view of the network or grid. The television camera forms the analyzer for the line and frame scanning. The side view through the inclined mirror enables a reduction the vertical space requirement of the device.

Downstream of the television camera, the analyzer preferably has a chronometric or timing circuit for the Delivering a time series of numbers of timing pulses in response to a time series of pulses of variable duration that come from the camera, a digital-to-analog converter that is responsive to the sequence of the Number outputs a voltage that is proportional to each of these numbers in succession, a coding circuit that a Emits a sequence of voltage levels which correspond to the previously determined discrete levels of the proportional voltage, and a television receiver known per se for displaying a large number of isobaric diagrams, each of which corresponds to one of the grids or an integer number of grids or image changes (trames).

The camera scanning of the strip network of the converter leaves square-wave pulses with a Latitudes that are a function of the pressure in the scanned zone, the pulses being temporal Sequence are arranged on the line signals. The time switch emits evenly spaced time pulses or Timing pulses during each pulse of variable duration, the number of times during a pulse with

509 8 4 8/0718

timing pulses emitted of variable duration are representative for the width of this pulse and thus for the pressure in the corresponding scanned zone. The digital-to-analog converter converts the sequence of representative numbers into a signal voltage with a value that represents the pressure in represents the zone scanned at the same moment. The coding or classification circuit gives gradations of the voltage with a discrete level corresponding to the detected pressures, the level transitions of the exceedance correspond to an isobar through the scan. The display of a large number of consecutive isobar diagrams on the television receiver, with each diagram being one of the grids or an integer number of grids or grids. Corresponds to a change of image, shows the chronological sequence of the distribution of the edition prints during the run.

Advantageously, the sampling analyzer has between the The camera and the timing circuit have a known isolating circuit with a first output for the television receiver supplied synchronization signals and a second image signal output which is connected to the timing circuit is. In this way the display on the television receiver coordinated with or synchronized with the examination scanner of the camera, while that of the chronometric The signal supplied to the circuit is freed from the synchronization signals, which are the function of the timing circuit or timing circuit would interfere.

Preferably, the timing circuit has a generator for timing pulses with a fixed repetition frequency. This generator is triggered or activated by the leading edge of the pulses with variable duration and by the The trailing edge of these pulses stopped. The timing circuit also has a binary counter with four digits or Places for counting the timing pulses and a memory

509848/0718

for storing the number output by the binary counter in response to the trailing edge. The binary counter is reset to zero in response to this number being stored. The arrival of a pulse with variable Duration thus starts the generator for the timing pulses, with the binary counter counting the successive ones Timing pulses to the end of the pulse with variable duration in the form of a binary number, between zero and fifteen counts. This number is entered in the memory at the end of the pulse with variable duration. On the , Storage follows the resetting of the counter to zero so that it can be used for the following pulse of variable duration is available.

The digital-to-analog converter is advantageously a binary converter with four inputs, each of which has one Scoring according to the geometric series with 2. This measure adapts directly to the parallel representation the binary number in memory.

The coding circuit advantageously has four response thresholds known per se, each threshold beforehand adjusted to a predetermined value of the proportional voltage corresponding to a selected pressure is. In this way, the isobar diagrams or images will be four easily distinguishable Gray levels are shown, each corresponding to a gradation and selected to be suitable for the isobars.

In an advantageous embodiment of the invention has the television receiver circuits for horizontal and vertical scanning, which are designed so that they ordinary scanning signals with in a fixed ratio Reduced amplitude step or staircase signals superimpose, the duration of the horizontal part of the step signal a multiple whole of the duration of the grid or

509848/0718

of the frame and the duration of the vertical part of the step signal are a multiple of the duration of the horizontal Part of the signal is. The usual scans with reduced amplitude give .an image which during of a horizontal signal part is also reduced, and that during the following Step described image is shifted horizontally so that in a horizontal line a number of successive different images appearing equal to the number of horizontal parts of the staircase is within the duration of a vertical part of the step signal, where V7is the number of steps of this vertical In part, a number of lines in the successive images is defined.

The invention is explained in more detail, for example, with the aid of the accompanying drawing.

Fig. 1 shows schematically an embodiment of an apparatus of the invention.

Fig. 2 shows the strips present in a converter of the device.

3 shows signals at various points on the analyzer in a diagram.

4 shows, in a diagram, scanning signals of the television receiver .

In the embodiment shown in Fig. 1, the total with 1 designated piezo-optical transducer a horizontal transparent plate 12, which by an edge in Direction of arrows 15 is illuminated so that the Light is captured by total internal reflection on the parallel surfaces 12a and 12b. On the plate 12 is a

509848/0718

- ο -

soft tape 13, the scattering inner surface 13a of a Network of sharp-edged parallel surface angles 14 is formed. A person's foot 11 rests while walking the horizontal area.

Under the converter 1, an inclined mirror 16 throws the from the transducer 1 on the surface 12a given image on the television camera arranged at the side. This camera 2 is one Television camera of conventional design, as used in standard closed-circuit television systems 625 lines and a 50 Hz picture change is used. The signals coming from the camera 2 become an isolating circuit 31 out, which on its output 31a the video signal freed from the synchronization signals and on their Output 31b gives these synchronization signals.

The video signals output at 31a reach the timing circuit 32, to which a generator for timing pulses 33 is assigned. The timing circuit 32 has a differentiating circuit, which is a control pulse with a sign in response to a positive transition of the video signal and outputs a pulse of the opposite sign in response to a negative transition of the video signal Gate, which controls the generator 33 for the timing pulses and in response to a control pulse with the first Sign open and closed in response to a control pulse with the second sign, a binary counter with four digits, which counts the timing pulses received from the generator 33, and a memory which receives those from the Binary counter counted number in response to a control pulse with the second sign and stores on reversal emits a pulse for resetting the counter to zero.

The generator 33 has a monostable circuit and a Delay line. The generator is switched to the active state by opening the gate of the timer circuit 32 offset. The monostable circuit provides a short one

609848/0718

Impulse responsive either to the opening of the gate or to a pulse that has been generated by the monostable circuit and has passed through the delay line. This delay line can be a suitable length of the coaxial line. The generator thus delivers one Train of regularly spaced timing pulses of the transition time in the delay line.

Each of the following numbers stored in the memory of the timing circuit 32 is transmitted through four channels - one for each binary digit - transmitted to the digital-to-analog converter 34. This conventionally built transducers are responsive to the presence of a state 1 in the value place of each Digit of the binary number to an analog adder a voltage corresponding to the power of 2 at this point. Arn exit The adder has a filter capacitance to absorb the conversion transitions.

The analog voltage of the output from the converter 34 Signal is fed to the coding or classifying circuit 35. This circuit has four parallel thresholds that are like this are graded to define four voltage levels corresponding to four graded selected pressure values. the Currents from these four thresholds add up in the active state and form a video signal that is sent to the television receiver 4 is fed. The transfer circuit of this video signal is overcompensated for high frequencies, see above that every level transition is accompanied by a crossing point.

The synchronization signals output from the separation circuit 31 via 31b are fed on the one hand to the television receiver 4 and on the other hand to a staircase voltage generator 36. This staircase voltage generator 36 has a separating device for raster signals or image change signals, a first one

509848/0718

-lo-

Frequency divider that can be set to produce a horizontal step pulse every one, two, four or eight raster synchronization pulses or frame change synchronization pulses emits a second divider that emits a vertical step pulse every five horizontal step pulses, and a third divider which outputs a vertical return pulse every two vertical step pulses. A first voltage generator for horizontal stairs speaks to horizontal step impulses over a step and to vertical step impulses via a return to the output, while a second vertical staircase voltage generator responds to vertical step pulses via a step and responsive to vertical return pulses via a return to origin.

The television receiver 4 has a conventional control gain for light. The sampling circuits are on the other hand modified as follows: The deflection is rotated 9o so that the line scan is vertical and the frame scan (balayage trame) is horizontal. The amplitudes of the sawtooth currents applied to the deflection are in proportion 1/5 reduced. These sawtooth streams are framing streams or image setting streams added by the the aforementioned staircase voltages are derived.

When, as shown in Fig. 1, a foot 11 on the converter 1 - stands, the edges of the dihedral angles .bzw. Ledges flattened on the plane of the converter 1 under the effect of normal pressures or vertical pressures. The intimate contact of the edges 14 of the diffusion surface 13a on the surface 12a of the transparent plate 12 locally lifts the total reflection of the light entering at the angle of incidence 15. This leads to the fact that the contact zones of the belt 13 and Plate 12 appear bright, so that a parallel network of light strips is formed as shown schematically in FIG. Where the tape is not exposed to any external pressure

509848/0718

is, the strips 14a of the mesh are fine or narrow. Where the external pressure prevails, the strips are widened "as shown at 14b.

In FIG. 3, the signals which occur at the various points in the analyzer 3 are shown. At output 31a the signals have the shape of curve 31o with a pulse 311 of reduced width, which corresponds to the resting of the edge under its own weight, a pulse of medium width, which corresponds to an intermediate pressure acting on the tape, and a broad pulse 313, which corresponds to the maximum pressure that can be measured by the transducer.

The curve 33o represents the timing pulses corresponding to the pulses 31o with variable duration. The pulse 311 corresponds to a single pulse 331, the pulse 312 a train of eight pulses 332, the pulse 313 a train of fifteen pulses 333.

The representation 32o shows schematically the state of the memory of the time measuring circuit 32 with the numbers in the superimposed lines, where white corresponds to the state one and the hatching corresponds to the states zero. After the pulse 331, a one appears in the memory, which is written in binary form with four digits 0001. After the pulse train, the eight appears, written 0100, after the train 333, the writing 1111 appears.

At the output of the digital-to-analog converter, the resulting proportional voltage would follow the course of curve 34o. At the output of the coding or classifying circuit 35, the steps of the voltage would have the course of the curve 35o with the passage peaks 351 at the level transitions, the passage peaks affecting the displayed images as a light ring at the positive transitions and as a shadow at the Translate negative transitions so that the line of isobars is highlighted.

509848/0718

In Fig. 4, the signals at the television receiver are shown schematically. At 354, both the video signals are above the Line of origin as well as the synchronization signals are shown, whereby the image change or raster synchronization signals are highlighted. At 4oo the components are the horizontal Scanning (image change or single image or grid, trame) is shown. The horizontal streams of stairs are at 4o1 is shown with a duration equal to a picture change. The superposition of the sawtooth grid of the horizontal scanning gives the course of 4o2. At 41ο is the shape of the streams the vertical scanning (line) analogous to 4oo with the difference that the sawtooth structure is not at high frequencies is recognizable.

If the sampling currents have the course shown at 4oo and 41o, the representation of the successive images has the course shown in Fig. 1 on the television receiver 4 with a first image line 41 to 45 and a second Row 46 to 5o.

Advantageously, the number of image changes or individual images shown can result from each of the successive Images are set so that the total duration of the displayed sequence of images is the full duration of the support movements of the foot covered during a step. A parallel representation of the sequence is thus obtained the support conditions of the foot. This form of representation is advantageously photographed. The documents received are analyzed and, if necessary, compared with a previously taken photo, for example to determine the success an intervention or orthopedic treatment.

The transducer can be in the form of an elongated path or path on which the person is moves, with the mirror and camera accompanying the person on their walk.

5.09848 / 0718

The television receiver can be registered by a device successive images are replaced, for example by a magnetoscope. In addition, the structure the circuits are modified accordingly, in particular with regard to the transformation and the pulse width the proportional voltage or for the stair framing.

509848/0718

Claims (6)

PATENT CLAIMS f 1 / apparatus for dynamically visualizing the encryption ^ ~ ^ distribution of the support pressure of the sole of the foot with a piezo-optical transducer which is composed of elements, which convert the supported pressure in intensity, and with a device for the sequential analysis of these elements for the Display of an isobaric diagram, characterized by a transducer (1) in the form of a flat plate (12) designed to form a network of parallel light strips, the width of the strips at each point being a direct function of the pressure normal on the Plate at this point, and through an analyzer with a line and raster scan, the line scan being perpendicular to the stripes. 2. Device according to claim 1, characterized in that that the transducer has a transparent plate (12) with parallel surfaces, which from the edge below are illuminated at an angle of incidence which corresponds to a total reflection on these surfaces, and a plastic band (13) which has a surface that diffuses the light and is supported by a network of sharp-edged V-shaped projections is formed, with the tape lying on the plate along the edges ". 3. Apparatus according to claim 2, characterized in that the plate is arranged horizontally and the analyzer has a television camera and an inclined mirror for side observation of the network. 509848/0718 4. Apparatus according to claim 3, characterized in that the analyzer has a timing circuit for the Delivery of a time sequence of numbers of timing pulses in response to a time sequence of pulses of variable duration coming from the camera, a digital-to-analog converter that is responsive to the sequence of numbers emits a proportional voltage to each of these number sequences, a coding circuit, which is a sequence of voltage levels corresponding to predetermined levels of the proportional Provides voltage, and a television receiver known per se for displaying a variety of successive images of isobars, each of these images being one of the individual images or image change or an integer number of individual images or grids. 5. Apparatus according to claim 4, characterized in that the scanning analyzer between the camera and the Timing circuit supplied to a per se known isolating circuit with a first output for the television receiver Having synchronization signals and a second image signal output, which is connected to the timing circuit connected is. 6. Apparatus according to claim 4 or 5, characterized in that the timing circuit has a generator for timing pulses with a predetermined repetition frequency, the generator by the The leading edge of the pulses with variable duration activated and stopped by the trailing edge of these pulses is, a binary counter with four digits for counting the timing pulses and a memory for Storing the number given by the binary counter in response to the trailing edge, the Binary counter is reset to zero in response to the storage of this number. 509848/0 718 '. Apparatus according to Claim 6, characterized in that the digital analog converter is a binary converter with four inputs, "each of which carries out a valuation according to the geometric series with 2". >. Device according to one of Claims 4 to 7 , characterized in that the coding circuit has four response thresholds. of known construction, each threshold being preset to a predetermined value of the proportional voltage corresponding to a selected pressure. . Device according to one of Claims 4 to 8, characterized in that the television receiver has horizontal and vertical scanning circuits in order to superimpose staircase signals in a fixed ratio on the usual scanning signals of reduced amplitude, the step duration of the horizontal staircase signal being a whole multiple of the picture change duration and the step duration of the vertical staircase signal is a whole multiple of the step duration of the horizontal signal. 503848/0718 A) - Blank page