DE2401618A1 - DEVICE FOR NON-DESTRUCTIVE DIMENSION MEASUREMENT - Google Patents

Description

PATENTANWÄLTE HENKEL— KERN - FEILER - HÄNZEL— MÜLLER

DR. PHIL. DIPL.-ING. DR. RER. NAT. DIPL.-ING. DIPL.-ING.

TELEX: 05 29 802 HNKL D EDUARD-SCH MID-STRASSE 2 BAVARIAN MORTGAGE AND

TELEPHONE: (OS 11) 66 31 97, 66 30 91-92. , ... "Λ _λΙ ηΐΐΕΜ on WECHSELBANK MÜNCHEN NR. 318 -85 IJl

TELEGRAMS: ELLIPSOID MUNICH U-8ÜUU MUNLHtlN yU POSTSCHECK: MCHN 1621 47 -809

Autech Corporation
Columbus, Ohio, V.St.A.

1 k JAN. 1974

Device for non-destructive dimension measurement

The invention relates to a device for non-destructive dimension measurement

In the case of manufacturing processes, a precise control and, if necessary, the control of the dimensional accuracy for the perfect functioning of machines and for the interaction of "their" Parts required. Also, it is desirable through better dimensional control and control the material consumption by adhering to the prescribed dimensions and in the « in particular to reduce the reject rate of workpieces in production.

In many industrial operations, the measurement system for the dimension control systems must be both non-contact and work continuously. For example, when rolling sheet material, the thickness measurement must be continuous to ensure the movement of the sheet metal strip not to have to interrupt, and to take place without contact, in order to disrupt the production process to be avoided by the measuring head.

Numerous types of electro-optic measurement systems for dimensional or dimensional testing have been developed that include

Mü / Bl / Ro -

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in turn are used for dimension control purposes.

A known optical measuring system works on the principle of the Michelson ¹ see interferometer. In this device, a light beam from a laser device strikes a beam splitter, which divides the beam into two parts. One part of the beam is reflected to a reference mirror and is then reflected back to the point at which the beam splitting takes place.The other beam part falls directly through the beam splitter onto a movable measuring reflector and is then also reflected onto the same point of the beam splitter If the light reflected by the measuring reflector is out of phase with the light reflected by the reference reflector, destructive or partially canceling interference occurs so that no light is transmitted to a detector. If, on the other hand, there is constructive or additive interference, a signal appears at the detector If the measuring reflector is offset by a quarter of a wavelength, the light at the point of interference changes from constructive to destructive interference, and the output signal of the detector changes from a maximum to a minimum g of the displacement of the measuring mirror from one point to another can be obtained. In the US-PS 3 398 287 a modified embodiment of this system just described is disclosed.

A second type of optical system is the zero detector according to IJS-PS 3 548 212. In the zero system, a laser beam strikes at a predetermined angle on a target or Target area on, and the backscattered Lioht is divided on a Photocell bundled. Both are in the zero position Photocells (parts) illuminated equally. If, however

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shifts the target, an uneven illumination of the photocells is detected and a servo amplifier entered with a downstream driver, which reset the laser and detector to a zero position. The amount of movement of the laser head arrangement is measured and displayed.

In the ÜS-PS 3 557 380 there is a modified Uull system shown. This patent discloses a transmitter or transmitter that emits a beam of energy, which is a small Illuminated area on a surface of a workpiece. A receiver has two detectors with each converging Sehtfeidern arranged on either side of the transmitter are. The detectors are aligned so that each detector covers the same part of the illuminated area Workpiece "sees" or scans when the latter is in the reference position. In the reference position are therefore the detector signals are of the same size, even if the reflection on the workpiece surface is uneven with respect to the spatial distribution is. When the workpiece is displaced, the detector signals change accordingly relative to one another of a predetermined function, and the signals are combined to produce a signal corresponding to the displacement combined.

ÜS-PS 3 536 405 discloses an optical thickness measuring device using a servo system. According to this patent specification a light source is provided which sends a light beam via a rotating prism onto a reflecting mirror projected. The light is transmitted from the mirror to a surface of the sample or the test piece and from there to an optical one System, a diaphragm slit and a photodetector reflected. The photodetector then generates an output pulse each time, when the light beam comes off through the aperture

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is keyed. A beam splitter, which is fixedly arranged opposite the light source, projects part of the light beam onto a second mirror mounted on a movable member · The latter reflects the light beam onto the opposite surface of the test specimen, where it is reflected back onto a photodetector via an optical system and a diaphragm slit. The second detector generates a second output every time the second beam is scanned via the second diaphragm slit. Amplitude-modulated pulses are converted, the amplitudes of which are proportional to the times of occurrence of the output pulses, The relative amplitudes for the adjustment of the movable member are relative to the fixed member via a servo system used. The displacement of the movable member indicates the thickness of the test specimen.

Furthermore, in US Pat. No. 3,437,825, a removal or Distance measuring system using a laser beam projecting device described, which projects two laser beams via converging beam paths from perpendicularly spaced locations onto a reference position. In a second, remote from the laser beam projector Position are perpendicular to each other and vertically adjustable relative to each other vertically adjustable beam receivers. If the vertical distance and the height of the two beam receivers are set so that both beam attachments receive the relevant beams, the height of the second position and its distance from the reference position can be accurate be starred.

Finally, US Pat. No. 3,541,337 describes "a width measuring system in which the width of a web or lag · medium · a photodiode and an oscillating prism optical

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A voltage jump is generated at the photocell if the light intensity varies on the scanning path, e.g. _o at the edges of the path or position, the angular position of the prism in which this voltage jump occurs is determined with the help of a toothed washer and inductive pickups a count of the pulses generated by the toothed pulley and the recipients interacting with it between the voltage jumps results in an indication of the web or layer width.

The optical systems described above in which the light amplitude or the relative light amplitudes are measured , for example with the Hull system, are sensitive to errors due to fluctuations in ambient light conditions, reflectivity and atmospheric conditions. Systems based on mechanical servo systems are working, because of the hysteresis that is to be expected in a mechanical drive arrangement, error-prone.

As a result, there is a need for a dimension measurement system with which measurements can be made independently of the judgment by an operator, the ambient light conditions, the Have surface reflection changes, mechanical restrictions and the like carried out ·

Starting from the mentioned measuring devices, in which the properties of laser light are used, is the The invention is based on the object of a laser * dimension comparator in particular for continuous measurement of the size, shape and degree of deformation of objects such as rubber jr * Plastic, food, glass, paper, textile and metal products to create the also duroh unskilled workforce can be handled with high accuracy and

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with which corresponding measuring tasks can be carried out quickly. This measuring device should have a digital display, which can easily be set for the display in any unit of measurement.

This task is used for measuring devices with a laser comparator solved in different ways according to the invention by the measures claimed in the independent claims, their advantageous developments in ühter claims Marked are.

The invention thus consists in a distance or distance measuring device, which supplies an output signal related to a distance dimension of a workpiece · This Apparatus has a light source for coherent light which falls on the workpiece in order to cause backscattered reflections induce. A light alignment device directs the light backscattered from the workpiece. Contains the backscattered light at least one comparatively large light intensity gradient, its position in relation to the distance to be measured in Relationship is · A photosensitive device is receiving the directed, backscattered light to determine the position or position of the intensity gradient by supplying an instantaneous value output signal which indicates the intensity is proportional to the light measured at the same moment. «A scanning device directs the reflected light onto the Photosensitive device to carry out a measurement in a lateral scanning sequence. The output of the photosensitive The device arrives at a signal processing device that relates to the time span between the scanning the intensity gradient responds. The signal processing device converts the output signal of the photosensitive Device into a signal that can be related to the distance to be measured «

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In the following, preferred implementation farms of the invention are explained in more detail with reference to the accompanying drawings demonstrate:

FIG. 1 a schematic representation of a measuring head with , Features according to the invention,

Fig. 2 is a view of a below the measuring head according to KLg * 1 arranged workpiece,

Mg · 2A is a graphic representation of two high spots Intensity on the workpiece according to Pig 2,

Mg · 3 «int front view of the control panel of a data processing desk according to the invention,

Hg * 4 a schematic representation of a modified embodiment of the invention,

yig 5 a thematic position of a further modified embodiment of the invention,

Pig. 6 and 7 are schematic positions of further modified embodiments of the invention,

fig 8 is a block diagram of a cable of the data processing circuit according to the invention,

fig. 9 is a block diagram of the remainder of the circuit according to »ig · 8,

10 «in the circuit diagram of the Saktoseillator according to fig · 8, fig. 11 «in Sehaltblit d« · Maßetabo · «illatοrs according to fig _# 8,

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FIG. 12 is a circuit diagram of part of the pulse form circuit according to FIG. 8,

Pig x 12A is a graphical representation of the output signal of the Yldikons according Fi g _o 1,

13 shows a circuit diagram of part of the pulse shape maintenance according to Fig. 8,

Figures 15A through 13F are graphical representations of the various Set the circuit according to Fig. 8 and 9 occurring signals,

Fig. 14 is a circuit diagram of that of Fig. 9 in block diagram form illustrated Hullstell Synohronieiereohaltera,

Fig. 15 is a circuit diagram of that of Fig. 8 in block diagram form analog circuit shown,

16 is a graphical representation of a series of waveforms illustrating the operation of an improved signal conditioning circuit for the comparator of the present invention and FIG

Fig. 17 is a detailed circuit diagram of a signal conditioning circuit which operates in the manner shown in Fig. 16.

The preferred embodiment of the measuring device with laser dimension comparator to be described generally has a measuring head and a data processing desk. The measuring head is arranged close to the object to be measured and supplies an output signal containing the dimensional information. The measuring head works with laser optics and an image converter

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electronics · The one that can be set up anywhere The desk is used to record and process the measuring head output signal and to generate the final display signal

1 and 2 illustrate the arrangement and mode of operation of a preferred embodiment of the measuring head according to the invention; 13 and 14, for example helium heon laser, and mirrors 16 and 18 interacting therewith. The laser devices and mirrors act as a source of coherent light which directs two coherent light beams 20 and 22 onto the workpiece 12 forming the target surface. As shown in the top view of I ¹ Ig ₀ 2, the coherent light beams 20 and 22 form two light spots 24 and 26 on the surface of the workpiece 12. Although the entire workpiece surface can be partially illuminated, the two light beams 20 and 22 form points with strong increased light intensity, as shown graphically in Fig. 2A. As will be explained in more detail, the distance between these two light spots 24 and 26 of high intensity is directly proportional to the distance from a point on the measuring head 10 to the workpiece 12.

The incident light from the light beams 20 and 22 is not only at an angle corresponding to the angle of incidence rather, part of the incident light is scattered back in all other directions. Part of this backscattered light, which is shown schematically in Mg * 1 is shown in the form of light beams 28 and 30, becomes a light-directing lens 32 mounted in the measuring head 10

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thrown. In the measuring head 10, a vidicon 34 is arranged relative to the lens 32 that an image of the two on it Light spots 24 and 26 of high intensity is focused. The lens 32 can typically have a focal length of 50 mm. The distance between the image spots on the vidicon is the actual distance between the light- spots 24 and 26 on the workpiece 12 representatively and thus directly the distance from the measuring head 10 to the workpiece 12 proportional. A power source 40 is used to feed the vidicon 34 and a laser power source 42, which in turn the laser devices 13 and 14 are powered.

A sawtooth waveform voltage generated by a horizontal sweep circuit 36 causes the electron beam from vidicon 34 to sweep horizontally across the vidicon screen in a conventional manner. As a result, after amplification by a video amplifier 38, the vidicon output consists of two pulses for each horizontal scan. Referring to FIG _e 12A, these pulses corresponding to the light spots 24 and 26, high intensity on the workpiece 12 according to Pig. 2 and 2A. The time interval Δ! between these two video output pulses, the actual distance between the light spots 24 and 26 is directly proportional. As a result, the time interval ΔT is also directly proportional to the distance from the measuring head 10 to the workpiece 12.

The relationship between the spacing of the Liohtflecken 24 and 26 and the thickness AD of the workpiece 12 is based on the geometry according to FIG. 1 can be seen. Examination of Fig. 1 shows that

D_
tan Cp »~ =

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where D is the distance from the intersection point to the to measuring surface and S the distance between the light spots 24 and 26 on the workpiece 12. Consequently is applicable

D - § tan q? = S

Da tan φ for a fixed installation in which the laser devices 13 and H and the mirrors 16 and 17 are fixed to the device, represents a constant, is applicable

D _x * KS,

where Έ. represents a fixed constant determined by the geometry of the system in question. The above remarks apply to the areas on both sides of the point of intersection.

To determine the thickness AD from a reference surface to the measuring area of a workpiece, the following equation applies:

-D ₀ -D ₁ -K (S ₀ - S ₁ ),

where'D ₀ and D. represent the reference surface or the measuring surface and S ₁ land S _{0 as the} distance between the spots on the workpiece surface and on the reference surface.

SI © mode of operation of a Tldicon therefore presupposes that the Ss-itspanne ^ S swisoll the Tiöeo output impulses, which & QU distance S swisehen the Liehtfleeken get intensity usiniü "ö @ llsai * proportional IsIj ₉ mithia ü®m distance from the ßbsr ^» goMieiöuagspunk -S; zur EIeSflache uns & tterbar psOporticaal i £ -i " _s Ms AusgajagsiEapulee- tSnneii äesm εο VQrarfesit © t werfiea ^ that

ί, fs a 5 5 fi / fs p «ΐ« 3 4 y -3 O & ti f Ό ¹ ^ ί «*

sioh for the reference area results in S ₀ = D ₀ = O, so that Δϋ = S ₁ K corresponds. The device according to Pig · 1 therefore generates two temporally separated pulses at its output, the temporal separation of which is directly related to the workpiece dimension AD.

The Pig. 4 and 5 illustrate two measuring heads modified from the measuring head of FIG. 1 which are used can in order to add two light spots to a picture tube surface generate whose mutual distance is directly proportional to a workpiece dimension.

In the embodiment according to Pig 4, a single laser device 50 delivers a light beam which falls on a beam splitter prism 52 which directs two light beams to mirrors 54 and 56 «Here, two light spots of high intensity are generated on the workpiece 57 in the same way as by the two laser devices according to Pig.1. A vidicon 58 is provided which detects these two light spots in the same way as in Pig _# 1. The beamsplitter prism is of conventional construction.

According to Pig. 5, a single laser device 60 directs a single light beam 62 onto a workpiece 70 in order to focus on it to produce a single light spot 63 of high intensity. However, there are two mirrors that are spaced apart from one another 64 and 66 are arranged in such a way that they direct the light scattered back from the single light spot 63 onto a prism 69.

The prism 69 is arranged opposite the mirrors 64 and 66 and the vidicon 68 so that it the two mirror images of the focuses a single light spot on a Vidikon 68. At the exit

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Guide shape according to Mg · 5 are thus two light spots high intensity generated on the vidicon, the distance between these light spots being directly one dimension of the workpiece 70, in the present case the distance from the workpiece 70 to the measuring head 10 is proportional.

In the Pig ", 6 and 7 further modified embodiments of measuring heads according to the invention are shown, with the previously described embodiments corresponding! Peile 6 and 7 denoted by the same reference numerals are. The embodiment according to FIG. 6 is similar to that according to FIG. 4 and has a vidicon 58 with a single laser light source 50. According to FIG Using mirrors 54 and 56 directed so that on the workpiece 57 two light spots are generated. In the embodiment according to FIG. 6, however, the prism is through one partially reflective and partially transmissive mirror 81 is replaced, so that preferably half of the coherent light from the laser device 50 passes through the mirror 81 is thrown onto the mirror 56 while the other Half of the light from the laser device through the mirror 81 passes and falls on the mirror 54 to be reflected therefrom. The embodiment according to Fig * is similar to that of FIG. 5 and again uses a single light spot 63 on the workpiece 70, which is through a single laser light source 60 is generated. The embodiment according to FIG. 7 requires some additional components, however, it has the advantage that it ensures beam paths of the same length from the workpiece to the vidicon 68. In addition to the Mirrors 64 and 66 for the direction of the light scattered back onto the vidicon are the measuring head according to FIG. 7 with two additional ones Mirrors 83 and 85 provided, which the light from the offset arranged laser light source 60 at a with point coinciding with the visual axis of the Vidikona 68

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straighten the workpiece. The embodiment is similar in this regard 7 that of FIG. 1, but it uses only a single laser light source and one single light spot on the workpiece.

The device shown in FIGS. 8 to 15 represents the signal processing device 35 connected to the output of the vidicon 34 according to FIG To convert Vidikons into a signal which can be related to a distance dimension of the workpiece “This device generates various output signals which indicate the measured dimension, namely a numerical display, binary coded decimal connections or _e- connections as well as analog connections or“ connections.

8 and 9, in block form, the digital processing network is shown shown showing the time interval between the vidicon output pulses in a digital display and converts a visual display of workpiece position or thickness. The operation of the data processing circuit 8 and 9 is controlled from a control panel according to FIG. 3. The control panel 25 has a digital display 80 on which a visual display of the desired dimension is offered. In addition, terminals are not shown provided via which the analog output signal and the binary coded decimal output signal was removed can be.

The laser comparator can work in two modes, both of which can be expensive from the control panel according to FIG. 3. When the measuring head is used to control a particular industrial Procedure is ordered, is located

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Reference surface in position D _Q (FIG. 1) at a fixed distance from the measuring head 10. In most systems, the position of the reference surface is on the opposite side of the intersection point 27 in order to keep the workpieces away from the measuring head, but it can The laser comparator is set with the help of devices to be explained in such a way that it delivers a Hull display when the light spots are formed on the reference surface in position D _Q. In the first operating mode, the Device, the actual thickness AD of a workpiece 12 which is located _{on the reference surface at D 0.} This operating mode is referred to as the operating point operating mode A representative signal for the measured thickness of the workpiece is stored in the memory section of a comm parator circuit saved. The output signal then emitted by the comparator when measuring a workpiece deviates from the measured thickness signal according to the dimensional deviation of the workpiece. For example, a workpiece can be placed on the reference surface and then the button 32 can be actuated to place the device in the deviating mode. Then the zero push button 84 is pressed in order to store the nominal dimension of the reference workpiece in the comparator. The digital display 80 then precisely shows the deviation of the thickness of a workpiece from the nominal thickness with a plus or minus sign in front of it.

The laser comparator has a linear working range, outside of which the comparator works non-linearly. A workpiece target surface on which the light spots are higher Intensity must therefore be formed within a

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the correct distance from the reference surface. An operating range meter 86 provides an analog display of the position of the workpiece surface with its indicator needle or pointer 88 inside or outside the operating area. In addition, a circuit is provided that has a signal lamp 90 lights up on the control panel according to Mg «3, to indicate that the device is operating in an area outside of its operating limits. The operating range is limited by the size of the screen of the vidicon 34 and the image reduction. If you see the workpiece further from If the measuring head is displaced, the light spots move further apart until they finally reach the edge of the vidicon screen and finally be mapped outside of this screen, with no meaningful display being obtained.

To compensate for light disturbances and electronic appearance as well as variations, the laser comparator can calculate the mean value the measured distance between the light spots during a time interval of 1/10 see or alternatively to be determined by 1 see. The mean value time interval is set manually by means of a control button 85

The circuit according to FIG. 8 is used to shape the pulses from Video amplifier 38 and to convert these pulses into a series of high frequency pulses which are then transmitted through the Counting and logic circuit according to Pig. 9 can be counted. The circuit has two different oscillators. A Clock oscillator 100 is used to control the logical punctures the circuit according to Mg. 9 and to control the Vidikon tent deflection Clock oscillator 100 is in Pig, 10 closer illustrated. It is crystal controlled and preferably oscillates at a frequency of 100 kHz. This oscillator can of conventional design in all other respects.

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The other oscillator is a scale oscillator 102, which is illustrated in more detail in FIG. The scale oscillator 102 supplies high-frequency pulses which are switched through and counted to determine the measurement dimension. Shown in Mg. 11 embodiment preferred of the scale oscillator 102 is also crystal controlled and, preferably, for example, operates at a frequency of 4.2 MHz, so that the display or in Mil _ö thousandths of an inch is supplied "by, optionally, a at a frequency of, for example, 10.6 MHz oscillating crystal is used, the circuit is able to provide a direct display in meters. The output or display scale of the digital display 80 according to FIG. 3 can thus be selected accordingly by selecting the crystal frequency of the crystal 103 according to FIG.

The output signal from the clock oscillator 100 shown in FIG. 8 becomes applied to a synchronizing divider 101, which is a frequency divider holding with three outputs. At the first output 104, the clock oscillator frequency is divided by 100, so that an output frequency of 1 kHz is provided, and these output pulses are called "ejection" pulses designated. At the second output 106, the clock oscillator frequency is divided by 10,000, so that a Output frequency of 10 Hz. At the third output 108, the clock oscillator frequency is divided by 100,000, see above that a frequency of 1 Hz is applied to this output. The divider output terminal 104 is on the horizontal wobble position 36 connected to the vidicon scan with trigger at a frequency of 1 kHz. The vidicon gropes consequently 1000 times per second and delivers 1000 output pulse pairs during each second, which correspond to the distance between the light fleoken of high intensity on the Workpiece are separated in time. The divisor

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Outputs 106 and 108 are applied to the logic circuit according to Jig * 9 for logic control clock purposes to be described in more detail _{in connection with Eg 4 9.}

The illustrated in Fig. 1 and receives in Mg. 8 is drawn in dashed lines video amplifier 38 at its input the separated time pulses in accordance with Figure _s 12A "The details of the video amplifier 38 are shown in Fig." 12 The video amplifier 38 has a potentiometer 120 for setting the vidicon target voltage, which compensates for ambient and target electrode reflection, and is provided with an amplifier 126 and pulse preform circuits in the form of a filter and amplifier stage 128 and an olipper stage

The output signal from the video amplifier 38 is applied to a video pulse shaping circuit 140 shown schematically in FIG. The task of this circuit 140 is to deliver a single pulse, the width of which is directly and precisely proportional to the distance between the light spots concentrated on the vidicon screen. The output of the video amplifier 38, which represents the input signal to the video pulse shaping circuit 140 is illustrated in FIG 13A .. _e The filter and amplifier stage 128, the induced Hauschen variations of the signal are eliminated.

13 illustrates the construction details of the first portion of the video pulse shaping circuit 140. According to FIG 13 shows the first stage of this holding 140 Differentiator 141 on. This differentiator differentiates the waveform shown in Fig. 13A to ensure a rapid. frequency of change for each light spot, which as

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~ 19 -

Reference value for measuring the distance between the high intensity light spots "should be used. The differentiated output signal shown in FIG. 13B is turned on a monostable multivibrator 143 (Hg · 13) is applied. The task of the multivibrator 143 is to deliver a square pulse for each light intensity pulse. The multivibrator is powered by the Pig. 13B at 160 and 170 are switched through. As a result, there is the output of the multivibrator of two consecutive square-wave pulses for each vidicon scan, with the leading edges of each Impulses have a fast rise time and are separated from one another by a time interval which corresponds to the Distance between the light intensity spots on the workpiece is directly proportional.

That in Pig. 13B output signal of the multivibrator is then to a not shown Stell / Rüekstellllip ^ -Plop applied, the latter generates a single square-wave output pulse, its width according to KLg. 13D directly corresponds to the distance between the light spots on the workpiece is proportional. The first output pulse 176 of the monostable multivibrator (Mg * 130) therefore offsets this Ilipw-Plop in his in! Ig. 13D position shown 178. The second output pulse 180 of the multivibrator brings this Plip ^ -Plop- into its reset state.

The output signal of the set / reset Ilip ^ -llop, which is shown in fig. S is shown as the output signal of the video pulse shaping circuit 140, is applied in a modified embodiment of the invention to a _{pulse stretching circuit 182 shown in Mg 4} , 8 in dot-dash lines. In the case of the preferred embodiment of the invention, however, the output signal of the video pulse phone circuit 140 is immediate

098 29/08 7 3

«20 -

applied to a scale gate 184. In the following only the preferred embodiment of the invention is explained, while the pulse stretching circuit is referred to later will be.

The output of the scale oscillator 102 is also impressed on the scale gate 184. The gate 184 is driven by the square-wave pulses (! Ig. 13D) from the video pulse shaping circuit 140. These pulses turn on the high frequency scale oscillator pulses applied by oscillator 102. The leading edge 186 of the output signal of the pulse shaping circuit 140 (Fig 13D _o) opens, therefore, the gate and thus allows passage of the pulses of the oscillator 102 to scale the output of gate 184 to. The trailing edge 188 of this pulse then blocks the gate in order to prevent further pulses from the oscillator 102 from passing through. In this way, the pulse width is converted into a series of pulses that can be counted. The number of measuring rod oscillator pulses present at the output of gate 184 with each burst of such pulses is directly proportional to the distance between the high-intensity light spots on the workpiece. In this connection it should be noted that there is a similar burst of such pulses at the gate output for each vidicon scan. In the preferred embodiment, the output signal of the gate 184 thus consists of a series of such pulse bursts which occur with a wobble or sampling frequency of 1000 bursts / sec.

The output of the scale gate 184 is to a Mean value divider 190 is applied, which has two selectively controllable outputs, the first output 192 being the in scale oscillator pulses contained in each pulse burst

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divides by 100, while the second output 194 divides the corresponding pulses in each burst by 1000. If, for example, in a pulse burst at the output of the Gate 184 2000 pulses are present, then these result in 20 pulses at the output terminal 192 of the divider 190 or 2 pulses at the output terminal 194 of the divider 190 *

The input signal of the mean value divider 190 is in Pig. ^{13I 1} shown schematically “These output pulses are then sent together with the synchronization divider output signals from terminals 106 and 108 in accordance with Mg“ 8 to the in! Ig. 9 applied logic circuit shown.

The logic circuit according to Pig · 9 is used to convert the Pulse bursts from the output of the mean value divider 190 in a digital display of the distance AD according to FIG. 1. As mentioned, is the number of pulses at the output of the mean value divider 190 immediately higher than the distance between the light spots Intensity proportional and therefore to the distance ΔΕ correlatable, and it is directly proportional to the distance from the measuring surface to the point of intersection.

Am selected of the two optionally selectable clock pulses At the outputs 106 and 108 of the synchronization divider 101, a logic circuit shown in block form in Pig «9 Synchronizing circuit 200 applied. Their task is there therein, at each input pulse from the sync divider 101 to deliver a sequence of three different output pulses to three different circuits 1 Hz clock pulse at terminal 106 to the synchronizer 200 is applied, one of three pulses occurs every second at the output of the synchronization circuit 200 existing sequence of control pulses. When the 10 Hz clock pulse output 108 is applied to circuit 200,

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every second, ten sequences of three pulses each occur at the output of the synchronizing circuit 200. The sequence of the three control pulses occurs immediately after the clock pulse from the synchronization divider 101. In the preferred embodiment, the three pulses have a very short duration, for example 10 / us each. All three pulses occur before a substantial scan of the vidicon has taken place, so that all three pulses appear before any pulse burst at the output of the mean divider 190 according to I ¹ Ig. 8 occurs. The function of these three control pulses is explained below

The bursts of output pulses from the mean value divider 190 according to FIG Pig. 8 are applied to a two-pole double-position switch 206. The output signal selected by switch 206 of the divider 190 is impressed on a counter gate 210. The output of this gate is in turn an up / down counter 212 is input.

The up / down counter 212 is a binary counter, the able to count in both upward and downward directions. He can thus accumulate every incoming impulse Add the total number of pulses or subtract each pulse from the previous numeric sum. The counter gate 210 controls the bursts of input pulses to the Up / down count3} to determine if this counter counts up or down. A counter direction circuit 214 controls the counter gate 210. This is a display memory 216 is provided in the form of a binary register, which contains the accumulated algebraic sum in the up / down counter 212 stores when it is instructed to do so by the synchronization logic circuit 200.

As mentioned at the beginning, the laser dimension comparator works gate after two operating modes. In the first, i.e. the working

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The digital display 80 shows the point mode immediately the position of the measuring surface relative to the point of intersection or - when using the pulse stretcher - directly that Thickness dimension AD. When operating in the operating point operating mode the zeroing synchronization switch 230 and the operating point memory 232 are not used.

The mode of operation of the logic circuit according to Pig «, 9 can initially be examined by starting at a point in time at which an output pulse from the synchronization divider 101 (Pig 8) at each of its output terminals 104, 106 and 108 is present. This 1 kHz output pulse on of terminal 104 initiates the scanning of the vidicon. At the same time, a pulse is generated from the relevant, selected clock output signals at terminals 106 or 108 to the synchronizer circuit 200 according to! ig · 9. Before an essential If scanning is carried out on the vidicon, a first locking pulse or locking pulse of short duration occurs at the Output terminal: 240 of the synchronization circuit 200. This inhibit pulse is applied to display memory 216 to allow data transfer from up / down counter 212 to the display memory 216 to initiate. When a zero is first stored in counter 212, the zero becomes display memory 216 transferred.

Now occurs at the output terminal 242 of the synchronizing circuit 200 an Irei pulse, which the counter 212 is impressed to clear it in a zero state. The free pulse is simultaneously applied to the counting direction 214 is applied to change its state so that it causes the counter gate 210 to the pulses control the up / down counter 212 in upward direction counts. A load pulse then occurs at the output terminal 244 of the synchronization circuit 200, which then occurs

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the zero switch 230 is put on «When the work point mode is selected, the zeroing synchronization switch is effective 230 only as an open switch, so that the load pulse has no influence

In summary, it can be said that the output signal from the synchronizing device before the occurrence Yidikon scan the up / down counter 212 cleared in its zero position, all existing data transferred from the counter 212 to the display memory 216 and the counter-gate 210 has switched to the count-up state. The number of pulses in the various Impulse bursts can now be stored in the up / down counter during the various scans of the yidikon or are accumulated.

If the switch 206 at the terminal 297 is set so that the input signal at the output of the mean value divider is divided by 100, the clock pulses from the sync divider 101 is applied to the synchronization logic circuit 200 at a frequency of 10 Hz. The counter 212 can thus store the counted pulses for a tenth of a second. After the first tenth of a second leaves an output pulse of the synchronization divider 101 appearing at terminal 106 a further locking "or" Blocking pulse at the output 240 of the synchronization circuit 200 occur. This will make the total accumulated in counter 212 to display memory 216. The upward s / down counter 212 is then triggered by a JPrei pulse at the output terminal 242 of the synchronization circuit 200, so that it can again count the following pulses begins ,, The counter 212 counts another series of Pulse bursts during a tenth of a second, which in turn are transmitted to the display memory 216.

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On the other hand, if the switch 206 is switched so that it receives the pulses from the mean value divider 190, which whose input pulses are divided by 1000, then the 1 Hz clock pulses from the synchronization divider output terminal 108 is applied to the synchronization circuit 200. In this state, the up / down counter stores 212 the pulses from the series of bursts at an averaging interval of one second. To the storage for one second causes the next 1 Hz pulse from sync divider 101 that the Total count accumulated in counter 212 is transferred to display memory 216 by a lock or lock. Blocking pulse at output 240 of synchronizing circuit 200 is initiated. Then sicii closes another counting interval from one second duration on "

The averaging is achieved in that the Switch 206 for averaging is switched over during a tenth of a second or during one second. if the mean value switch 206 is connected to terminal 197,

the averaging follows for a tenth of a second. Since the vidicon samples at a frequency of 1 kHz, 100 samples are taken every tenth of a second. 100 pulse pulses are thus applied to the input of the mean value divider 190 during a tenth of a second. By dividing the pulses by 100, the number of pulses at the output 197 of the mean value divider in an interval of one tenth of a second is equal to the average number of pulses in a single pulse burst. As a result, an average number of pulses is obtained for an average scan of the vidicon _β

When switch 206 is thrown to terminal 199 so that it has an output signal divided by 1000 from the central

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value divider receives, the 1 Hz clock pulses are sent to the Terminal 103 applied to the synchronization circuit 200, Under these conditions, the counter 212 stores the total number of pulses occurring during one second « During one second, the vidicon scans 1000 times so that it delivers 1000 bursts of pulses · by using these pulses · am Mean divisor 190 divided by 1000 becomes the total number of times during a one second interval the pulses appearing at the output terminal 194 of the mean value divider equal to the average number of pulses, which occur in a single scan. The up / down counter thus stores the average Number of in a single scan of the vidicon existing pulses and averages it over a selected interval of one tenth of a second or a second.

A standardized reference workpiece is used in the deviating mode arranged on the reference surface, the position of its measurement surface being indicated by the laser dimension comparator should be This position display is stored in the comparator as a reference value · Then others can Workpieces are arranged under the measuring head, the digital display 80 showing the dimensional deviation of this other work « shows pieces of the standardized reference position dimension. The real one Thickness can be determined by storing the position of the reference surface and then reading it off through the workpieces caused deviation can be read.

For operation in the DevBich operating mode, the Switching the Fullstell-Synchronisiersohalter 230, which in a simplified, basic form is a single-pole one-position switch 249, which is switched on between the input 250 and the output 252 »The switch 249 is

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by the one on the control panel according to Pig. 3 accessible Operating mode selector switch 254 activated. This selector switch 254 is used to select the work mode in its closed position and to select the deflection mode switched to its open position. The simplified zeroing synchronization switch 249 is added controlled by the zero switch 265. When the operating point mode is selected, the is Simplified zeroing synchronization switch 249 open, so that the load pulses appearing at input terminal 250 have no further influence on the circuit.

When selecting the deviation mode, however, the zeroing synchronization sierschalter 249 is closed, so that the load pulses from the terminal 244 of the logic synchronization circuit 200 to the counter 212 and to the counting direction Sehaltung 214 can be applied _o

Basic operation in the deviating mode usually begins with the mode selector switch 254 being opened to select the deviating mode. This automatically closes the zeroing synchronization switch 249. The standard workpiece is then brought under the measuring head and the operator presses the zero setting switch 256 to have the device store the position of the standard workpiece. To carry out this device function, when the zeroing switch is pressed, the synchronization switch 249 is first opened for a period of Z ₀ B ₀ two seconds in order to let the comparator operate in the operating point mode during this period. Here, the position of the measuring surface of the standard workpiece in the manner described in connection with the operating point mode

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Display memory 216 is stored. In addition, the Depressing the zeroing switch 256 also provides an output signal from the zero setting synchronization holder 230 to the Terminal 260 generated, whereby the data from display memory 216 to operating point memory 232 is transferred. The two second period ensures that the Device works in the operating point mode and measures the actual or actual position regardless of whether an averaging of one second or one tenth of a second is used. This also ensures that that the position measured and displayed in the display memory for use in the deviation mode is stored in the operating point memory. After expiration the time span of two seconds the zeroing synchronization switch 249 automatically closed again, and the circuit now stands for the reproduction of the dimensional deviation other workpieces from the dimensions of the standardized workpiece ready.

In the deviation mode, a clock pulse is received from the sync divider 101 is applied to the logic synchronization latch, creating a sequence of three output pulses will. As with the operating point operating mode, the first pulse is a blocking pulse at output terminal 240, which is impressed on the display memory 216 in order to display all of the data contained in the up / down counter 212 to overwrite. The next impulse is then the price impulse at output a terminal 242 of circuit 200, which is applied to the up / down counter to clear this counter and return it to JFuIl. In addition, the ^ rei-impulse is also applied to the double directional alignment 214, to put them in their count-up state. the Circuit -214 therefore first switches counting gate 210 so that the latter the input pulse bursts for counting

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let the counter 212 controls. However, the load pulse now appears at output terminal 244 of the circuit 200, and this last pulse is closed over the Zeroing synchronization switch 249 to the counting circuit 214 created. This last pulse switches the Circuit 214 switches to its countdown mode. The circuit 214 in turn controls the counting gate 210 to the down counting terminal of the incoming pulse bursts To control counter 212.

At the same time, the load pulse is also applied to the up / down counter in order to overwrite the stored data from the operating point memory 232 into the counter 212. The logic circuit is now ready to begin counting the pulses in the pulse bursts which appear during the periodic sampling of the vidicon at the input to the counter gate 210. The up / down counter 212 now starts counting the pulses during a. Total time span of one tenth of a second or one second, depending on which averaging has been selected, with the exception that this is done in exactly the same way as in the operating point mode, the total number of times during one tenth of a second or _e during one Second counted pulses is directly proportional to the position of the measuring surface of the workpiece inserted under the measuring head.The main difference, however, is that the counter 212 begins its counting process from the number transferred into it from the working point memory 252 and counts down from this overwritten number to count to zero.

When the in-mode Deviation is remotely located to be measured workpiece is a smaller piece than the Bezugswerkstüok from the intersection point _S is one of the up / down

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Counter not completely to zero. Instead, the synchronization circuit 200 is activated by the next clock pulse operated when the counter 212 has reached a number which represents the deviation of the measured workpiece from the Corresponds to the reference workpiece. As before, actuation of the logic synchronization 200 initially a blocking pulse is generated which first transfers this number from the counter 212 into the display memory 216. A triple pulse is then applied to counter 212 to clear it and reset it to Hull. The load impulse is then reapplied to the counter 212 to put the stored operating point back into the up / down counter 212 to overwrite.

Since the number displayed is smaller than the number corresponding to the position of the measuring surface of the shaped workpiece, is indicated by a sign storage circuit 270 displays a negative or minus sign on the digital display 80. This pre-emption memory circuit 270 receives the output from the count direction circuit 214. So often the latter is in the counting-up state, saves the prefix memory « circuit the positive or plus sign. If, on the other hand, the circuit 214 is in the down-counting state, then store Circuit 270 cheats the minus sign, "The inhibit pulse at the output terminal 240 of the synchronization circuit 200 is applied to the sign storage circuit 270 so as to keep the sign stored in the digital display 80. In the pail of a workpiece with undersize is therefore the count direction circuit 214 is still in its countdown state at the end of the counting process if the Data in counter 212 is overwritten into display memory 216. As a result, the subsequent blocking pulse switches a minus sign from the sign memory at output terminal 240 270 for digital display 80 «

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In the following, the order of the processes is now seeks if the measuring surface of the workpiece is further from Point of intersection is removed as the measuring surface of the reference workpiece, with which the former is compared. As just described, the up / down counter 212 begins in the operating mode deviating from the reference operating point in sighting counting down on mull. However, if the dimension of the measured workpiece is larger than the reference dimension, it counts the counter 212 is completely on Hull and then begins like " to count the hooh. This is because the counting circuit 214 contains a logic circuit which continuously receives the data from the up / down counter 212 receives from its output 270. If this logic-so-hold circle detects a Hull in the counter 212, it switches the counting device 214 to the exponent mode camouflage. This in turn toggles the gate to control the pulses to the count up terminal of counter 212, and additionally to switch the sign memory 270 to a plus sign.

The up / down counter now starts counting up, counting up to a number which represents the excess deviation of the measured workpiece. The next clock pulse operates the synchronizing circuit 200 to rewrite of the data from the up / down counter 212 into the display memory 216, then the counter 212 on To free the garbage and to initiate a second counting process again the operating point memory data in this Enter the counter.

fig. 14 Illustrates the details of the liullstellgyz & hronisiereohaltere 230 "This switch 230 has two relays 502 and 304, each of which actuates a two-pole double-.ötellu22g3" BofealikQ2rfcakt 30β "bswa 503, Ber

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230 also has a 2 second time delay circuit 310 provided which the circuit after pressing of the zeroing switch 256 for two seconds in the operating point mode.

By briefly pressing the zero setting button 256 the time delay circuit 310 is actuated. In doing so, it immediately applies voltage to relay 302 and relay 304, whereby the terminal 260 is grounded. The first effect of this process is that the Working point memory 232 which is stored in the display memory 216 (lig. 9) available data. If the relay 302 drops out later, the operating point memory keeps the last one in the display memory 216 contained in the data. By connecting terminal 260 to ground, the display 80 is connected to ground and thereby freed, so that during this interval of two seconds a digit display is prevented.

When it is excited, the relay 304 is in the operating point- Operating mode brought. If the mode select switch 254 were closed, the relay 304 would of course be constantly excited, so that the comparator would be in the operating point mode »With switch 254 open however, if the comparator is in the deviation mode, it will through during the two second period the switch 308 is switched to the operating point mode. While working in the In the operating point mode, the thickness of the reference workpiece is stored in the operating point memory in the manner described.

After the period of two seconds has elapsed, the time delay circuit leaves 310 the relay 302 and the relay 304

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fall off. As a result of the opening of the switch 306, the Operating point memory 232 keep its stored data ". The contact 308 operates as shown in FIG. 9 as a simplified switch 249. When the contact 308 is closed the input terminal 250 is connected directly to the output terminal 252, so that the load pulse from the output 244- der Synchronizing circuit 200 to the up / down counter 212 and to the counting direction circuit 214 according to FIG can.

According to I ¹ Ig. 8 an analog display of the workpiece dimensions is also provided. For this purpose, the output signal of the video pulse shaping circuit 140 is applied to an analog circuit 402. As mentioned, the output signal of the video pulse shaping circuit 140 is a square-wave pulse, the width of which is directly proportional to the distance between the intense light spots and therefore to the position of the workpiece. In addition, the 1 kHz clock pulse at the output terminal 104 of the synchronizing divider 101 is applied to the analog circuit 402. The output signal of the analog circuit 402 is fed to the range display 86, which according to Pig. 3 is visible on the control panel of the comparator. In addition, the output of the analog circuit 402 is input to a range limiting circuit 412 composed of two comparators. One of these comparators lights up the work area limit lamp 90 on the control panel of the desk according to Pig «, 3 when the measured value exceeds the height limit of the system. The other comparator causes the working range limit lamp 90 to light up when the lower measuring limit of the system is exceeded.

15 illustrates the details of the analog hold, which left an analog output signal at its terminal 502

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ready. The size of the analog output signal is immediate proportional to the width of the pulses coming from the output of the video pulse shaping circuit 140 to the input terminal 504 can be created. The input terminal 506 of the analog circuit according to Mg. 15 is connected so that it the 1 kHz clock pulses from output terminal 104 of the Synchronization divider 101 according to FIG. 8 receives “Die Aus ~ Output pulses from circuit 140 become the input terminal 504 and then a set / reset flip ^ -flop 508 and impressed on a monostable multivibrator 510. The 1 kHz clock pulses at terminal 506 are the flip ^ -J'lop 508 fed in and are used to reset the same.

A sawtooth wave generator generally designated 512 is connected to an integrating capacitor 514, the discharge of which is controlled by a transistor 516. Of the (Transistor 516, in turn, is controlled by flip-z-flop 508 activated · A sample storage capacitor 518 picks up the voltage value at the capacitor 514 and stores it as often the field effect transistor 520 for a short time- * span locks. A DC amplifier, indicated generally at 522, applies a DC reference voltage to the Terminal 524 and the tap voltage to terminal 526 a differential amplifier 528 whose output amplitude directly to the width of the pulses applied to the input terminal and therefore directly to the position of the is proportional to the workpiece located under the measuring head.

The pulse width of the pulses applied to input terminal 504 is tapped 1000 times every second. The sequence of operations of the analog circuit begins with the application of the 1 kHz clock pulse to terminal 504. This clock pulse ^{resets the I 1} IiP _- , -FIoρ 508, which allows the transistor to turn on to switch the capacitor 514 to a normal one

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Discharge level to be discharged The leading edge of the Videc input pulse the PIip_— Plop hits terminal 504 508, which then brings transistor 516 into its blocking state. As a result, the current from the Constant current generator 512 charge capacitor 514; so that a virtually linearly increasing sawtooth voltage occurs across capacitor 514.

The sawtooth charge of capacitor 514 continues at. The trailing edge of the input pulse at the terminal then actuates the monostable multivibrator 510, which switches to its working state for a few microseconds, to field effect transistor 520 via a DC level shift circuit 530 to be switched through.

During this period of several microseconds, the sample store capacitor 518 charges to the voltage of capacitor 514. The multivibrator 510 then returns to its original state, and the field effect transistor 520 is brought into its locked state. Stores for the remainder of the one millisecond period the capacitor 518 the tap voltage. This voltage is amplified and sent to terminal 526 as well as to the differential amplifier 528 created. The tap or sampling voltage level is then still applied to terminal 526 until the field effect transistor in the next period 520 is switched through again and a new scanning process is carried out «

At the beginning of the next sampling period of one millisecond duration, the clock pulse is again applied to terminal 506, to reset the flip ^ -flop 508. This will the capacitor 514 is discharged again to a normal discharge level, but this has no effect on the sampling

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storage capacitor 518 has. During this second sampling period the new charging sawtooth voltage crosses over the capacitor 514, whereby, as before, the trailing edge of the input pulse at the terminal 514 the field effect transistor 520 can be switched through to again the charge voltage of the capacitor 514 during an interval of a few microseconds. If the voltage on the second scan is greater than the first, charges the storage capacitor 518 increases to a higher value. If the second sampling voltage is less than the first, it charges the capacitor 518 to a lower value. «The voltage level of the capacitor 518 is passed on to the differential Amplifier 528 is applied until the next scan occurs. The sawtooth charge of the capacitor 514 lasts until the end of the one millisecond interval. This ensures that during each one millisecond sample period the capacitor 514 is charged to the same value and becomes therefore always discharges to the same normal or target discharge level during discharge.

Without filtering in differential amplifier 528, it would Output signal consist of a series of short steps or stages. To avoid this state is in the circuit of the differential amplifier, a smoothing filter 532 is provided.

The selection of the frequency of the scale oscillator 102 is now explained below with reference to FIGS. 8 and 9 The result of the correct selection of the frequency of the scale oscillator 102 is one of the particularly advantageous Features of the invention. This explanation also relates to the function of the optionally provided pulse stretching circuit 182 and the calibration of the laser comparator, see above

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that a number of stored by the up / down counter 212 pulses counted in Binäranzeigespeicher 216 immediately converted by a decoder 217 in a DezimalzifferAnzeige and dimensions can be displayed in a corresponding unit system as the measured dimension or _e.

A typical example will now be considered on the basis of the previously explained mathematical considerations. The geometry of the optical system according to Pig. 1 can be chosen, for example, in such a way that the intersection point 27 of the incident Light rays 20 and 22 is regarded as a reference point, so that the reference distance S is equal to zero. the The geometry of the optics can typically be designed so that a workpiece having an OD of 5.0 mm (200 mils) leads to a pixel spacing on the screen of the vidicon of 12.7 mm. A typical horizontal scan length across the vidikon screen is about 25.4 now.

When the number of pulses counted by the up / down counter 212 is converted to digital digits and immediately is to be shown on the display, the series of digits must be the number of counted pulses indicate the same series of digits representing the measured dimension of the workpiece. In which typical example mentioned above, the number of pulses measured in each pulse burst should be 200 or 2000 or but be any other decimal multiple of 2. The scale oscillator frequency can therefore, for example be chosen so that during each vidicon scan 2000 oscillator pulses are passed through to the up / down counter. These 2000 impulses would be immediate generate the binary-coded decimal number according to the decimal number 200 »

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If, on the other hand, the scale oscillator frequency is chosen is that during each scan of the vidicon 508 pulses or a decimal multiple of this number of pulses for up «· up / down counters are switched through, the same circuit would indicate 508. Place the digits 508 represents a dimension of 200 mils in centimeters. Since the scale oscillator 102 illustrated in greater detail in FIG 103 is controlled, these design principles can be applied such that by selecting an appropriate Crystal allows the selection of the unit system according to which the device works. To this No further adjustments or modifications to the laser comparator circuitry are required for this purpose.

In the typical example cited above, the 12.7 mm spacing between pixels on the vidicon screen and the scan of about 25.4 mm on that screen require that about 4000 scale oscillator pulses be generated during each scan of the vidicon. Since the vidicon scan is performed at a frequency of 1 kHz, the scale oscillator must operate at a frequency of approximately 4 MHz in order to provide the required number of pulses during each scan. Given an assumed frequency of the scale oscillator 102 of 4 MHz, 2000 pulses are switched through to the output of the scale fatter 184 during each one millisecond scanning of the vidicon. Typically, however, the scale frequency is 4.2 MHz so that a retrace is possible and yet 4000 pulses per vidicon scan are available. As a result of the averaging system described, the counter counts 2000 pulses during each tenth of a second or each second during which the average value of the count is formed.

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The horizon is used to calibrate the laser comparator precisely al scanner 36 with a conventional sawtooth height adjustment Mistake. The sawtooth wave height is adjusted until the dimensions of a standardized workpiece are known exactly the correct number of pulses is counted and displayed on the digital display 80 · This height setting is of course used to adjust the total scanning length of the Vidikon screen, and it stretches or shortens consequently the time it takes for the vidicon electron beam to move from one light spot to the next needed. In this way the time width of the gate pulse becomes from the output of pulse shaping circuit 140 to provide just the correct number of scale oscillator pulses is switched through to the mean value divider 190.

If now a pulse stretching circuit 182 is connected between the pulse shaping circuit 140 and the scale gate 184 is, which increases the pulse width by a selectable, fixed amount of time, increases as a result Pulse counting and thus the display position by a fixed value hence the reference area actually at a different location than be arranged at the ray intersection point 27 according to FIG. 1, the displacement of the reference surface by corresponding Adjustment of the pulse stretching circuit 182 can be compensated · If the reference area for example by about 2.5 mm is arranged offset from the intersection point 27 relative to the measuring head, the pulse stretching circuit should give the pulse a add such a time width that an additional 1000 pulses can be switched through to the counting circuit.

Figures 16 and 17 illustrate an improved and preferred signal conditioning circuit for the invention • according to the laser dimensional comparator. Fig. 16 illustrates

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a series of voltage waveforms to explain the operation of the circuit, while JFig _o 17 is a detailed schematic of the signal conditioning circuit. In the preferred embodiment, the circuit according to FIG. 17 replaces the circuits according to Mg _0, 12 and 13, that is _, "the video amplifier 38 and the pulse shaping circuit 140 according to Pig", FIG.

In Fig. 16, a voltage waveform or a voltage evaluated as a puncture of time is shown at 602, which represents a typical output signal of the yidicon of one of the previously described embodiments of the invention, for example the output signal of the vidicon according to FIG. 1 or the Vidikons 58 or 68 according to the I ¹ Ig. to 7. The ones in Pig. 16 Uull voltage line labeled OV is indicated at 604 for waveform 602, which in turn consists of two pulses 606 and 608, which correspond to the high-intensity light spot images bundled on the surface of the vidicon. or spurious components represented by the slightly wavy line 610.

An important feature of the laser dimension comparator according to the invention is that it is the distance or, more precisely, the time difference between the peaks 612 and 614 of pulses 606 and 608, respectively, and not the leading edge or any other parameter of those pulses measures. One of the reasons for this is that if the comparator is used for measuring contoured surfaces or surfaces with elevations and depressions is used, the angling of the surface in question changes the light spot intensity, resulting in a difference in amplitude between two pulses, such as the pulses

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606 and 608 results. However, changes in the pulse amplitude between two successive pulses lead to a change or a shift in the detectable leading or trailing edge of the pulse and to an erroneous deviation of the apparent distance between the pulses resulting therefrom. By measuring the peaks or vertices 612 and 614 of successive pulses, however, the effects of the pulse amplitude are largely suppressed, since the pulse peak always occurs in the center of the pulse, so that a much more accurate measurement of the pulse interval _or the time difference between successive pulses can be achieved »

The output from the Vidicon is by an Olipperschaltung with a cut-off or indicated by the dashed line 616 Cut-off level passed through. As a result, the interference-free waveform indicated at 618 is achieved since the Noise level is below the clipping level, the waveform having gate pulses 620 and 622. The leading edge 624 and the trailing edge 626 of the pulse 620 correspond to the times at which the leading and trailing edges of the pulse 606, as indicated at 628 and 630, cross the clipping level line 616. The front and trailing edge of the second pulse 622 at the times when the voltage pulse 608 crosses the clipping level line 616 cuts. The voltage line for the Waveform 618 is indicated at 632.

The signal represented by waveform 650 from is also sent through a differentiator in hindu, the differentiated around the Uull reference line 636 Create waveform 634. When differentiated, the pulse 606 results in a pulse pair with a negative pulse

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638 and a positive pulse 640 passing through a zero intersection 642 are connected to each other. Similarly, the vidicon pulse yields 608 when differentiated a negative pulse 644 and a positive pulse 646 connected by a zero intersection 648 are. The noise signal, which has been slightly amplified by the differentiator, is shown by the more wavy line at 650 indicated.

Waveform 634 is determined by a comparator or zero intersection detector which is indicated by waveform 652, about the zero voltage reference line 654 output signal lying around produces · This waveform contains the further amplified noise signal 656 and two pulses 658 and 660. The leading edge 662 of the pulse 658 coincides in time with the intersection 642 of waveform 634, and the leading edge 664 of pulse 660 similarly coincides in time with the intersection.

The pulses 620 and 622 of waveform 618 are used to gate pulses 658 and 660 to turn off the Noise signal 652 used. More precisely, the waveforms 618 and 652 are combined in an AND circuit, . around the waveform 666 according to Pig. 16 relative to the zero voltage reference line indicated at 668 to he " witness. Waveform 666 contains two narrow, sharp pulses 670 and 672 that are free from noise signals and whose leading edges 674 and 676 coincide in time with the intersection points 642 and 648 of the waveform 634 and consequently also in time with peaks 612 and 614 of the vidicon output waveform 602 match. The distance d between the leading edges 674 and 676 represents the time difference between the occurrence of the vidicon scan over the

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, two light spot images bundled on the vidicon higher Intensity and is in turn representative of the dimension to be measured.

By clipping the vidicon output signal and using it of the cut impulses as gate signals, it is possible to to considerably increase the responsiveness of the dimensional comparator. More precisely ;. By filtering how in the embodiment previously described, accurate measurements can be made over a vidicon amplitude range of about 10: 1 can be achieved. Attempting to expand the measurement range introduces errors and small vidicon output pulses are lost in the noise signal. By the gate technology ensured with the circuit according to FIG it is possible to increase the amplitude range of the detector up to 50: 1.

According to Figure 17, the _e the vidicon output signal is generally applied 602 to the input terminal 678 of a signal conditioning circuit 680 designated. The vidicon output is amplified in a current amplifier 682 and then passed through a voltage amplifier 684. The output signal from amplifier 684 appearing on a line 686 is, as indicated at 688, an amplified and reversed pulse pair which is fed to a voltage comparator 690, which acts as a clipper circuit and squarer and delivers two gate or activation pulses 692 on its output line 694. The cut-off or cut-off level indicated by the dashed line 696 is set by means of the grinder 698 of a potentiometer 700.

The signal conditioning circuit 680 is provided with a test terminal 702, which via a buffer transistor 704 with the Voltage amplifier 684 is connected. The output signal of the voltage amplifier 684 passes through one of .einem

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Capacitor 708 and a resistor 710 ″ to the input of a second voltage amplifier 712. The differentiated waveform 714 appearing at the output of amplifier 712 is fed to a DC value changing amplifier 716 in order to generate an amplified output signal 718 on its output line 720 Waveform 718 is an amplified version of the differentiated waveform 714 "but in which the DC value" or level is changed to produce shorter and sharper pulses in either the upward or downward direction, such as "in the illustrated Pail. Evidently, causes the DC value change in the same displacement of both pulses, wherein the spacing between the pulses is not affected by the DC level _E, the line 720 feeds a zero-volt-detector or · intersection detector 722, which is triggered by the Gatterimpülse 692 on line 694 or is switched through in order to generate the narrow pulses 724 at its output. These pulses are passed through a converter 726, a monostable multivibrator 728 and an output buffer amplifier 730, in order to deliver the pulse pair 734 at the output terminal 732, the leading edges of which determine the distance indicating the dimension to be measured. This pair of pulses is processed by the remainder of the apparatus in exactly the same manner as described in connection with the previously discussed embodiment, it being noted that the signal conditioning circuit 680 only uses the video amplifier according to Pig. J2 and the pulse shaping circuit according to Pig. 13 replaced. The circuit according to Pig. 17 is based on a T -quaHsrenden logic, and all the amplifiers 709 shown are provided with a blocking or interlocking protection, in that a rectifier diode (not shown) of the 1N67 type is connected between the terminals 6 and 8 of each amplifier.

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Although only a few preferred embodiments and specific exemplary embodiments are disclosed above are, these are only intended to explain the invention and in no way restrict it, as the laughing man takes it for granted various changes and modifications are possible without departing from the lame and basic concept of the invention will.

In summary, the invention thus makes a non-destructive one working dimension measuring and comparing device created, in which a beam of coherent light is thrown onto a workpiece surface so that it is on this forms one or more spots of light «, that of that or light that is backscattered from the light spot (s) is thrown onto a vidicon screen in order to at least image two light spot image points that are spaced apart from one another at a distance corresponding to a dimension of the workpiece are arranged. The vidicon is scanned to produce output pulses proportional to the distance between the light spot images are temporally separated from one another. A scale oscillator generates scale pulses that switched to an up / down counter by the electronically processed, temporally separated pulses will. A logic circuit counts and reproduces the switched-through scale pulses to display the dimension, or it compares the count with a reference value and shows the deviation.

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Claims (1)

Claims 2401618 / 1 ο) Measuring device with a laser dimension comparator for generating an electrical output signal that indicates a distance measure, for example on a workpiece, marked by a laser light source that directs coherent light onto a workpiece in order to generate at least one laser light intensity level on the latter. were used to generate a photodetector arranged next to the light source for receiving the image of at least one backscattered laser light intensity gradient from the workpiece and a scanning device coupled to the photodetector for scanning the surface of the photodetector and for delivering an electrical signal pulse which indicates the position of the image on the photodetector indicates 2. Apparatus according to claim 1, characterized in that the laser light source has a device which has two Directs laser beams of coherent light onto the workpiece, and that the scanning device means for generating has two electrical signal pulses which indicate the position of two backscatter images from the workpiece correspond to the photodetector. 3. Door direction according to claim 2, characterized in that the laser light source comprises two laser devices for generating separate light beams. . 4. Apparatus according to claim 2, characterized in that the laser light source has a single laser device and a beam splitter which divides the light from the single laser light source into two beams. 409829/0873 5. Device according to one of the preceding claims, characterized in that the laser light source is a Device for directing a single beam of coherent light onto the "workpiece" and one next to the photo detector arranged optical device for generating two backscatter images from the light intensity gradient of the single beam on the workpiece. 6. Apparatus according to claim 5, characterized in that the optical device has two on both sides of the single beam light reflectors arranged in coherent light having. 7 · Device according to one of the preceding claims, characterized characterized in that an electrical signal processing circuit for detection is connected to the scanning device the time of occurrence of the electrical signal pulse during a scanning process of the scanning device connected. 8. Device according to one of the preceding claims, characterized in that the signal processing circuit means for determining the time of occurrence of the peak of the electrical Having momentum. 9 · Device according to claim 8, characterized in that the photodetector is a vidicon and that the scanning device is coupled to the horizontal scanner of the vidicon Sawtooth generator is. 10. Measuring device with a laser dimension comparator for generating an electrical output signal which is a distance measure for example on a workpiece 40982 9/0873 characterized by a laser light source that directs a single beam of coherent light onto a Workpiece aligns and thereby a single laser light intensity gradient on the surface of the workpiece generated, a photodetector arranged next to the light source, two arranged on both sides of the light beam Light guide devices for generating two backscattered light intensity gradients on the surface of the photodetector based on the gradient on the Workpiece, and by an electrical circuit connected to the photodetector for generating an electrical Output signal showing the position of the light beam images on the surface of the photodetector. 11. The device according to claim 10, characterized in that the electrical circuit has a device for generating a signal indicating the distance between the images. 12. The device according to claim 11, characterized in that the signal is the distance between the centers the images indicate. 13. The apparatus according to claim 10, characterized in that the light beam comes directly from the laser light source falls on the workpiece «, 14. The device according to claim 10, characterized in that between the laser light source and the workpiece at least an additional light guide device is arranged, which the light beam from the light source on aligns the workpiece surface. 409829/0873 15. The device according to claim 14, characterized in that the light beam through the additional light guide device is thrown practically vertically onto the workpiece » 16. Measuring device with a laser dimension comparator for Generation of an electrical output signal that indicates a distance, for example on a workpiece, characterized by means for directing coherent light onto the surface of a Workpiece for generating at least one laser light intensity gradient on the workpiece, a photodetector arranged next to the workpiece, one between the workpiece and the photodetector arranged light guide device for generating two spaced-apart Backscattered light intensity gradient images the surface of the photodetector starting from the workpiece, a device connected to the photodetector for Scanning of its surface for the purpose of generating two temporally separated electrical pulses which the Specify the distance between the images, and a signal conditioning circuit connected to the scanning device to generate a second pair of electrical pulses, the edges of which correspond to the time interval between the centers of the first pair of pulses are separated from one another in time. 17. The device according to claim 16, characterized in that that the photodetector is a vidicon with a horizontal scanner for scanning the surface of the vidicon 18. The device according to claim 16, characterized in that that the signal conditioning circuit has a first device for generating tactile signals from the first 409829/0873 2407618 • Pulse pair, a second device for generating pulses with edges which correspond to the centers of the first two pulses, and a gate connected to the "two devices" for controllable switching of the pulses from the second device depending on the load signals. 19. Device according to claim 18, characterized in that the first-mentioned device is an Olipp circuit is. 2Oo device according to claim 19 »characterized in that that the second device comprises a differentiator and an intersection detector. 21. The device according to claim 16, characterized in that that a scale oscillator for generating oscillator pulses at a selected pulse frequency and a A scale gate is provided which receives the signals from the signal conditioning circuit and the scale oscillator receives that the scale gate is controlled by the signals from the signal conditioning circuit to the To switch oscillator pulses through to the scale gate output, and that a counter coupled to said gate for counting the output pulses of this gate within a selected time interval as well as an output memory for storing those stored in the counter Counting are provided. 22. The device according to claim 21, characterized in that a circuit for averaging is provided, the mean value divider connected between the scale gate and the counter for the delivery of output signals, the number of which is that of the scale gate 409829/0873 Output pulses divided by a selected number Έ corresponds, as well as clock and synchronizing devices for controlling the counter for the purpose of storing its count for a number of Ή output signals of the signal conditioning circuit. 23 ο Device according to Claim 22, characterized in that the counter is a logical synchronization device. to define a time sequence of command pulses at its output depending on an input clock pulse, the command pulses comprising a blocking, a free and a load pulse, of which the blocking pulse is passed to the output memory to instruct this to 'count the To rewrite counter and to keep that an up / down counter, which is instructable for the algebraic addition of each pulse to an accumulated algebraic sum of the number of pulses in a certain period of time and which is switched so that it the switched through scale oscillator pulses as well as the free and Load command pulses from the logical synchronizing device receives, a direction control and sensing device for controlling the counting direction of the up / down counter, the inputs of which are connected to this counter, in dependence on a selected pulse of the logical synchronization circuit and depending on the occurrence of a zero state i n to count up in this counter and to count down depending on a second selected pulse from the logic synchronization circuit, a memory device for defining an operating point for storing the count in the output memory device depending on the actuation of a zero switch with an up / down switch Output connected to the counter for overwriting the operating point storage on the named counter in ab- AO9829 / 0873 Fear of the occurrence of the load pulse on this Counter, a zeroing synchronization switch device, which is switched in such a way that it activates the load pulse of the logic synchronizing device the up / down s counter and the counting direction control and button programming depending on the actuation of the zero switch interrupts, and one connected to the counting direction sirer and sensing device Sign storage device are provided, which in response to a countdown command to a Minus sign state and in the case of an increment command transitions to a plus sign state. 24. "Device according to claim 23, characterized in that that between the scale gate and the counter a mean value divider for supplying output signals, their Number of those of the scale gate output pulses divided by a predetermined number N, is switched on and that a clock and synchronizing device to control the counter to store its count for the number of N output signals of the Signal conditioning circuit is provided. 25. The device according to claim 24, characterized in that that a clock oscillator to control the scanning device ' device and the logical synchronizing device is provided and that a synchronization divider is switched so is that it divides the clock oscillator output by appropriate decimal divisors and the pulses the highest frequency applied to the scanning device. 26. The device according to claim 25, characterized in that that the clock oscillator with a frequency of 100 kHz works so that the output signals from the synchronized! - 409829/0873 ler are at frequencies of 1 kHz, IO Hz and 1 Hz, that the scale oscillator operates at about 4 MHz and that the mean value divider optionally selectable division modes for dividing by 1000 and by 100. 409829/0873