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Publication numberUS2927836 A
Publication typeGrant
Publication dateMar 8, 1960
Filing dateMay 29, 1953
Priority dateMay 29, 1953
Publication numberUS 2927836 A, US 2927836A, US-A-2927836, US2927836 A, US2927836A
InventorsSidney X Shore
Original AssigneeSidney X Shore
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Photographic speed monitor
US 2927836 A
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Description  (OCR text may contain errors)

March 8, 1960 s. X. SHORE 2,927,836

PHOT OGRAPHIC SPEED MONITOR Filed May 29. 1953 3 Sheets-Sheet 1 REA/ZOFCAR OETECTOR lab 1 /7A /777/I LF il I vzaa 3m I L- J /36 INVENTOR SIDNEY x. SHORE 4 i 12 g ATTORNEY March 8, 1960 s. x. SHORE 2,927,836

PHOTOGRAPHIC SPEED MONITOR Filed May 29. 1953 3 Sheets-Sheet 2 TIMER (ml/119M515 5 FUPFLOP) INVENTOR SIDNEY X. SHORE BY ATTORNEY March 8, 1960 s; x. SHORE 2,927,836

PHOTOGRAPHIC SPEED MONITOR Filed lay 29, 1953 3 Sheets-Sheet 3 INVENTOR SIDNEY X. SHORE ATTORNEY United States Patent 2,927,836 PI IOTOGRAPHIC SPEED MONITOR Sidney X. Shore, East Rockaway, N.Y.

T 7 Application May 29, 1953,Serial No. 358,233 I 21 Claims. (Cl. 346-107) The present invention relates to methods and apparatus for measuring the speed of vehicles and photographing vehicles passing the detection point at excess speed.

Various devices intended to accomplish this purpose have been devised heretofore, involving doppler radar for speed measurement aswell as pneumatically or mechanically or photoelectrically operated switches at spaced points along a traific lane. So far as I am aware, all of these systems are deficient for photographing the speeder for several reasons. Theyare poorly adapted to the use of electronic flash lighting, which is highly desirable if stop-motion sharp pictures are to be obtained throughout a Wide range of-change in natural lighting conditions. As a practical consideration in the use of electronic flash or strobe lighting, as this form of photographic lighting has come to be known, the lighting must be aimed in such direction as to avoid blinding the driver of the vehicle being photographed. A second requirement is that the strobe illumination should be consistently at a point as close as possible to the vehicle being photographed in order that the lighting may be intense and in order that the lighting may be confined to the immediate region of the vehicle to be photographed so as not to extend, uncontrolled, to other traflic lanes where drivers might be blinded thereby;

The present invention provides a practical speed detection and photographic system wherein strobe lighting may be used at short range with reliance that the vehicle to be photographed will invariably present its license plate at the particular restricted region where the strobe light ing is effective. This is accomplished advantageously by employing the highly localized forms of vehicle detectors that are embodied in minimum-elapsed-time speed measuring devices, suchas pneumatic tube actuated switches,


speeding vehicle close to that one being photographed.

The system is not seriously defective however if it should photograph the front end or the center of a speeding vehicle without recording the license plate since this represents only the waste of a film and an omisslon by the detection system. An innocent driver is not atfected by such misoperation, and the fact that an, occasional speeder may escape detection is of little consequence when it is realized that the present speed detection practice as conducted by patrolmen can apprehend only a small percentage of speed-law violators.

With the foregoing in view, the present invention provides various forms of speed detector, and camera combinations which are responsive to the rear of the vehicle being paced. In one type, the speed detector is disahled until the rear of the vehicle has passed a point close to the speed measurement apparatus. Of this type, 'one form disclosed in detail below involves equalizing the counts of wheels passing a first detection point and wheels passing the first element of an elapsed-time form of speed measuring system. A second form disables the speedmeasuring device While all except the rear end of the I vehicie passes the speed-measuring region. This form photocells, and the like, in a system which responds to the rear end of a vehicle, rather than to the front end or an uncertain portion of the vehicle as has characterized other systems that I have heard of. It is accordingly feasible in this new system to photograph the rear of a vehicle which may be illuminated by a downwardly sloping strobe beam directed at the rear of the vehicle. This direction of the beam is best suited to safe use of strobe lighting. To achieve this therear of the vehicle is to control the process irrespective of whether the vehicle involved is short or very long, and whether it has two axles as in pleasure cars, or three or more axles as in the case of trucks and trailer trucks.

The foregoing system has the advantage that, even i. apart from strobe'lighting, the rears of speeding vehi -cles may be photographed so as to record the license plates which are invariably carried at the rear of vehicles, where only in certain states are the vehicles equipped with front license plates. 4

The systems involved are intended to function as reliable and automatic substitutes for traiiic patrolmen and for this reason should be as perfect aspossible in order that one vehicle that is proceeding --within legal limits may-not be photographed asthe result of detection of a renders the speed-measuring equipment effective after the rear of the vehicle passes a predetermined point. T h s second form has the feature in common with athird form disclosed below in detail, in that the measurern nt Qf speed can commence as soon as the rear of the ve icl 'e passes a certain point in the traffic lane. In this third system, a unitary detector of therear of the vehicleserves also as a first detector of a speed-measuring combination. In the fourth system, the speed measurement is initiated by the vehicle and is not suppressed by the rearof-thevehicle detector, but that detector is effective by virtue of storage or holding means to act jointly with the speed measuring means to trip the camera.

The nature of the invention and its various further features of novelty and their advantages will be best appreciated from the following detailed description of three illustrative but highly effective embodiments theteof, which are shown in the accompanying drawings. Inthes e drawings:

Figures 1, 2, 3, and 4 are combined wiring diagrams and schematic representations of four different embodiments.

In Figure I, a vehicle 10 is illustrated travelling along a trafiic lane 12 across which are stretched three pneumatic hoses 14, 16 and 18. If multiple trafiic lanesare found side by side, it would probablybe expedient to confine the hoses to a single traflic lane and to employ a duplicate system foreach of the adjacent lanes. Hoses I6 and 18 are nearer to each other than the minimum spacing between succession Wheels of usual cars and trucks. A camera 20 is provided, conveniently supported as on a lighting pole at the edge of the road or by any other suitable means, with the camera trained verting stored electrical charge, as of the order of 55), watt-seconds, in a flash commonly lessin duration than of a second. The carnera andthe strobe lighting unit are synchronized by'hnown means, commonlylby utilizing contacts in the camera shutter mechanism which fire the strobe unit at the instant that the shutter is fully open. Strobe unit 22 includes thestrobe lamp 22a together with a reflector 22b; and it further advantageouslyincludes a louver 220 for confining the light beamto the region where the license plate 1,031 (many vehicle actuatingthe tube 18 might be located without,

however, allowing stray light to reach oncoming traffic. Camera 20 is of any desired construction, advantageously incorporating automatic film advancing mechanism and incorporating auxiliary devices for recording date, time, location and speed. The camera employs an electromechanical actuator 20a that is eliective to trip the shutter instantaneously and initiate the film feeding cycle.

Hoses or pneumatic tubes 14 and 16 act together to initiate the speed measuring process which is completed under control of hose 18. Ina sense hose 14 is a rearof-the-vehicle detector, or simply rear detector" and hose 16 is a first speed measuring detector.

Each of the hoses is pneumatically coupled to a pair of pressure-actuated contacts 14a, 16a and 18a, respectively, in a manner well known and accordingly not described in detail here.

Each of these contacts has a power supply 14b, 16b and 18b which energizes a related solenoid 14c and 16c in the first two instances; and supply 18b energizes electro-mechanical actuator 20a of the camera at appropriate times.

Solenoids 14c and 160 include step switches with fixed contacts 14d of which six are illustrated, and each step switch includes a moving contact 14c that is advanced stepwise by the solenoid 14c. Solenoid 16c similarly actuates a step switch having fixed contacts 16d, the same in number as contacts 14d and the moving contact 160.

Between contacts 14:: and 16e there is connected a voltage source 24, a capacitor 26 and a resistor 28, in series. This series circuit is completed when moving contacts 14c and 16s are in like positions so as to be interconnected by a wire 30. One such wire interconnects each fixed contact 14d with a corresponding fixed contact 16d. A resistor 32 shunts condenser 26.

In operation there is a steady potential at junction 34 where condenser 26 is connected to resistor 28. This is a small voltage where resistor 32 is large relative to resistor 28. When the front wheels of a vehicle engage hose 14, contacts 14a are closed and moving contact 14e is advanced one step to the next fixed contact 1411 and the next wire 30. At this time the charge in condenser 26 starts draining through resistor 32. Hoses 14 and 16 are spaced sufliciently, as 20 feet for example, so that the next wheels of the approaching vehicle pass hose 14 before the first pair of wheels reach hose 16. If there are three axles (as in a large truck) hoses 14 and 16 are separated farther apart than the greatest separation between any successive pair fo axles. Accordingly,

contact 14c advances once more before the first wheels reach hose 16. Ultimately the vehicle wheels cause contact 16a to advance the same number of steps as contact 14c; and when this happens, the series circuit described is completed. Momentarily the voltage of direct current source 24 is transmitted via condenser 26 and is largely impressed on resistor 28; but this decays as condenser 26 becomes charged. By this process a sharp pulse is developed across resistor 28, at junction 34 with respect to contact 16a.

In the foregoing process, hose 14 acts to count axles or pairs of wheels and hose 16 (with its associated apparatus) counts similarly, the counts of the first hose being equalized with the counts of the second hose only when the last pair of wheels has actuated hose 16. The equalizing process is one of equal addition or of subtraction, depending on ones point of view.

It will be evident to those skilled in the art that the electro-mechanical counters 14c, 14d, 14s and 16c, 16d, 16e may be replaced by other well-known forms of counters such as the vacuum tube or gas tube ring counter; and the counters employed may utilize any convenient number of counter positions. Suitable means (not shown) may be provided for insuring that the counters are zeroed or set to corresponding positions than when they are at rest; and with equivalent electronic ring counters, the zeroing operation is accomplished readily as is well known.

the vehicle.

When the same number of wheels has passed hose 16 as previously passed hose 14, a pulse is developed at point 34 that initiates the start of a timing operation. This may be accomplished in a wide variety of electromechanical and electronic ways. The following is an etiective illustrative embodiment. Rectangle 36 represents a timer. This rectangle encloses a monostable flipfiop of well known design as is described in volume 21 of the Radiation Laboratory Series published in 1948 by McGraw-Hill, at pages 591 and 592. Briefly, this timer incorporates a pair of vacuum triodes 38 and 48. Each triode has its own load 38a, 40a where load 4011 conveniently is in the form of a relay whose contacts 4% are open so long as the relay is energized. These triodes have a common bias resistor 39 so that current passed by one triode reflects bias into the other. Triode 40 has its grid operating normally at a high positive poten tial, derived through resistor 40c that is connected to B-plus. The control grid of triode 38 has a bias that is fixed at a suitable value by voltage divider 38b, 38c that is connected between B-plus and B-minus. A condenser 42 furnishes cross-coupling between the anode of triode 38 and the grid of triode 40.- The values of resistor 40c and condenser 42 are chosen to provide the right time interval between the initiating input pulse and the end of the timing pulse generated by the flip-flop. This operation is as follows:

In normal operation triode 40 conducts amply to energize relay 40a and open contacts 40b, and thiscurrent provides bias across resistor 39 that exceeds the drop across section 380 of the voltage divider sufficiently to drive triode 38 well into cutoff. When a negative pulse is transmitted from junction 34 through condenser 44, that negative pulse initially is transmitted to the grid of tube 4t), which tube is immediately cut off, and the charge thus developed in condenser 42 must take time before it has discharged through resistor 40c sutiiciently to allow tube 40 to conduct again. This involves substantial time and the effect is sudden because, so long as tube 40 is cut off, tube 38 is conductive and develops grid bias for tube 40 in resistor 39.

During the operation of the monostable flip-flop 36 relay contacts 40b remain open. This time is determined by almost all of the values employed in the flip-flop. This time interval is chosen so that a set of rear wheels passing hose 16 will fail to reach hose 18 for any vehicle speed up to the legal limit. Thus for a speed of 60 miles per hour or 88 feet per second, and for a spacing between hoses 16 and 18 of four feet, the contacts 48!) will remain closed for approximately /22 of a second.

If a vehicle should traverse the hoses 16 and 18 in less than the time interval for which contacts 4% are closed, a circuit is completed between contacts 48b, 18a and camera tripper 20a. This circuit is energized by supply 18b, to trip camera 20 and photograph the rear of vehicle 10 including license plate 18a, with the aid or" the illumination from synchronized strobe lighting unit 22.

It is significant that in this system the operation of the timing apparatus under control of contacts 16 and 18 is suppressed until the rear wheels of the vehicle to be photographed reach hose 16 and consequently the rear of the vehicle will be in position to be photographed if the vehicle has exceeded the time interval permissible. The precision of the location of trippers 16 and 18 is excellent so that the camera can reliably be counted on to frame the rear of the vehicle accurately. However, if by some mischance hose 16 should initiate the timing cycle before the rear wheels have passed, e.g. under control of some other set of wheels forward of those rear wheels, the consequence would be to photograph some middle portion of Such misoperation is entirely unexpected; but even if it should occur, there is no penalty imposed on an innocent driver and the only result is the inconsequential escape and failure of detection of a speeder.

Ordinarily there will be no reliable rep at operation of i-to make contact by vehicle-wheel pressure.

{he-camera in response to each set of wheels because of several limitations. Itis desirable that timer 36 may relia'b'lyeesume its steady state'condition with condenser 42 line reasonably steady state of charge before each new =timingcycle; and more important is the practical limitation that the high intensity lighting unit 22 should not be called upon tooperate more frequently than is necessary. For presently practical designs of adequately powerful .units, one flash per second is as frequent as should be depended upon.

-It is possible for the front wheels of a second vehicle to engage hose 14 before the rear wheels of the first vehicle have reached hose 16; and this would suppress operation oftthe timer irrespective of whether that first wehicle were speeding. Thus if hoses 14 and 16 were :separated by 20 feet (corresponding approximately to the maximumepacing between axles of a trailer-truck) it would be possible for cars separated by less than feet from bumper to bumper to be so close to each other as to :suppress detection of the first vehicle if it were speeding. :Suchcloseness is most improbable at highway traflic speeds. However, the controlling consideration is that the escape of an occasional speeder is of minor concern so long asthesystem prevents charging an innocent driver withspeeding.

It is possible for two vehicles to travel so close to each,

:speeder is of secondary concern so long as the system does not operate wrongly to charge the innocent with speeding.

A range of equivalents .for pneumatic hose-operated switches will beapparent to those skilled in the art. Without limitation, it is evident that normally separated con- .ductors carried in a hose with one lying above the other can be used to complete a circuit directly without reliance I on pneumatic pressure and pneumatically operated .switchesf Such devices have the special advantage of being precisely localized so as to make possible the accurate measurement of speed even were the separation between hoses 16 and 18 somewhat less than the illustraftive four feet suggested above. Thus two separate electrical impedance or proximity detectors and the like .appear to be of limited value in the embodiment of Figure 1 as substitutes for hoses to and 1,3.

In Figure 2 there is shown an alternative form of systemmeeting the requirements detailed in connection with the description in Figure 1 without relying upon the pneurnaticwform of hose and without relying upon the wheel .Counter type of vehicle rear detector. Where like parts .are used in Figure 2 as appear in Figure 1, like numerals .are used, prefaced bythe numeral 1' so as to represent the lOO-series numerals. Their description and operation will not be repeated in detail since this will be understood- "from the description of Figure 1.

Referring to Figure 2, it is seen that pairs of Wires 116a and 118a are stretched across the trafi'ic lane in substitution for the pneumatic 'hosesof Figure 1. Each pair of "wires is normaliy resiliently spaced apart but is actuated After the rear of vehicle 119 has passed the rear detector 114, timer Starting detector 116a can become effective to initiate the timing operationof unit .136 which, as injFigure 1, may ,be a monostable ,multi-vibrator or flip-flop. Unit 156 should be understood as embodying suitable'control-signal generation means corresponding to elements .24 to 32,

inclusive, in Figure 1. ,Normally closed contacts will be open when a vehicle is in proximity to detector 114.

the input control for timer 136 extends through contacts Normally open contacts 140];

116a and 50 in series. are seen to be connected in series with contacts 118a to energize camera tripper 120a if the wheels strike contact 118a while contacts 14012 are still closed. It will be understood that in Figure 2 the same camera and strobe lighting installation is involved as in Figure 1 directed at the rear of the vehicle as it passes pressure-actuated contacts 118a, but the showing of those elements is omitted as unnecessary to proper understanding.

The time suppressing control in Figure 2 which 1r,e places the counters of Figure l involve a wire 114 that is connected to an impedance detector 52. This may take a wide variety of forms. Thus wire 114 may be an antenna connected to an oscillator that is readily disturbed by the presence of a vehicle above it as in proximity fuse and mine detector applications, or the element may simply represent an upwardly directed photocell whose activation is obtained from the sky, obscured so long. as a vehicle is travelling above it. However, as illustrated, element 114 is a wire constituting one element of a capacitive impedance between that wire and one of the wires 116a. That capacitive impedance is substantially reduced so long as a vehicle is in proximity to both. When the rear of the vehicle has left wire 114 and the axle is approaching wire 116a, the normal capacitance may be essentially restored. This capacitance is represented by the dotted terminal capacitors 115. The capacitance is greatest when a vehicleis in proximity to both wires and it is quickly reduced to approximately the same as prevails when no vehicle is present as soon as the rear of the vehicle passes wire 114 appreciably.

The capacitance is measured by a purely illustrative capacitancebridge involving a condenser .54 that approximately equals the capacitance between wires 151.4 and 116a when no vehicle is' present; a pair of matched resistors 56; an alternating current signal source 57 con nected between one diagonally opposite pair of bridge terminals, and an unbalance amplifier 58 with its relay coil 58a having input connections to the other diagonal terminals of the bridge. An isolating condenser 60 is interposed between wire 116a and the terminal of the bridge to which that wire is to be connected. The condenser is very large compared to the capacitance between wires 114 and 116;; and is employed so that wire 116a may also serve as a timer contact. A second wire may be employed adjacent to the pair of wires 116a,'duplica ting wire 114 at this other position near wires 116a,!but the double function arrangement illustrated makes that other arrangement superfluous.

In operation, contacts 50 are normally closed. The

bridge is balanced. This balance is disturbed when the overhanging front end of a vehicle approaches wires 116a and extends above wire 114. This causes contacts 50 to open so that, thereafter, thefront wheels engagement with wires 116a is ineffectual to start the timer. .Later, when the rear of the vehicle has appreciably passed wire 114 the bridge is suiliciently rebalanced so that contacts 50 are closed and the rear wheels are then effective to initiate timer ope-ration. Ultimate photographic recording of the vehicle rear end follows as described in connection with Figure 1, under control of timer 136.

A third embodiment of the broad aspects of the invention is illustrated in Figure 3 in which the rear-ofthe-vehicle detector also accomplishes the function of timer starting. Whilea photocell is illustrated, a variety of impedance-change detectors such as is represented by the well known proximity fuse may be substituted. Photocell 214 is connected in series with a resistor 202 sistor 206. Whenno vehicle is present photocell 2'14 ducts maximum current. cell 214 and obscures the sky illumination, the current -in tube 204 drops and a positive pulse is produced at tion region.

is fully conductive and correspondingly tube 204 convhen a vehicle covers photothe anode of tube 204. This pulse is transmitted via condenser 244 (corresponding to condenser 44 in Figure 1) that energizes monostable flip-flop 236. This flip-flop is insensitive to positive pulses, so that nothing takes place in response to the covering of photocell 214. However, when the rear of the vehicle has passed photocell 214 so that tube 264 once again conducts at maximum current, a negative pulse is transmitted to timer 236 (l ke timer 36) which initiates the timing operation. During this timing operation contacts 24% (corresponding to contacts 40b in Fig. 1) remain closed so that if contacts 218a should close during the timing interval, camera tripper 220a would be operated. This occurs when the rear of vehicle 210 no longer covers photocell 218. This photocell is connected in series with resistor 2-08 between B-plus and B-minus with resistor 2&8 connected between the grid of triode 211 and B-minus. So long as the car covers photocell 218, tube 211 remains non-conducting (or conducting a nominal current) and relay 213a has 'open contacts. However, when the rear of the vehicle has passed photocell 218, tube 211 conducts heavy current to energize relay 218a and close its contacts. Only if the closing occurs within the time that contacts 24% are closed will camera 22th: operate. If contacts 24tlb open before contacts 218a close, it is established that the vehicle has travelled at the permissible rate and should not be photographed.

It the rear of the vehicle has passed detector 214 before the front has reached detector 218, contacts 24% and 218a will both be closed simultaneously and the camera will be tripped. The result will be to photograph the front end of the vehicle from the camera situated above and to the rear of the intended framed position of the license plates of speeding vehicles. This is a spurious photograph that does not evidence speeding, and is wasteful but does not result in wrongful charges against the innocent. However to avoid this contingency it is desirable to position photocells within six feet of each other so as to avoid such spurious operation.

The photocells advantageously incorporate tubes or optical lens systems to make them sharply directional.

To avoid response to the space between a bumper and a body or between a trailer and the hauling truck, it will be advantageous to aim the photocell directional system slantwise, as toward the approaching traific.

Detectors 214 and 218 are illustrated as being photo cells arranged to be responsive not to the interruption of light occasioned by the entry of the vehicle but rather are arranged to be responsive to the restoration of normal conditions that prevail when no vehicle is present, indicating passage or departure of the vehicle from the detec- Other sharply localized object detectors, as magnetometers, apparatus designed as mine detectors radiationresistance-change radio detectors andthe like. These have the advantage that they remain efiective despite the presence of road dirt that may be somewhat of a problem in the case of photocells mounted in the road and upwardly directed. However the dirt problem is readily solved by proper mechanical installatiorn'and the sharply localized property of the photocell is of immense advantage to this problem.

Prominently characteristic of all three embodiments of the broad aspects of my invention is the feature that the rear of the vehicle initiates timing. In the forms of Figs. 2 and 3, this may detect the rear of the vehicle physically where a photoelectric or like vehicle-rear detector is employed. This may respond to the restoration of lighting conditions prevailing when no vehicle is present, or to the restoration of capacitance existing in the system when no vehicle is present, or to the restoration of normal effective antenna resistance in the region of the vehicle-rear detector; or it may be responsive to the rear set of wheels in particular. The application of localized forms of detectors, e.g. the photocell, the pressure-actuated switch, the radio-frequency impedance change detector, all adapt the system to accurate location of the vehicle that is to be accurately framed in the camera field and in the strobe lighting beam. These localized forms of vehicle detectors, integrated into the elapsed-time type or speed measuring system, enables speed measurement in a restricted accurately defined region that helps to avoid spurious operation of the camera in photographing one slow vehicle in response to another speeding vehicle that may escape unidentified. In broad concept however, it is not considered beyond the scope of the present invention to employ a localized doppler radar beam or the like for speed measurement without dependence upon elapsed-time systems of speed measurement.

In each embodiment detailed above, a speed measuring or gaging system is combined with a detector responsive to the rear of the vehicle. Tripping of the photographic apparatus aimed at the vehicle rear is the joint result of vehicle-speed gaging and vehicle-rear detection; but in the foregoing embodiments the gaging system is suppressed by the vehicle-rear detector and is initiated into operation by the rear portion of the vehicle.

it is entirely feasible to measure or gage vehicle speed without regard to what part of the vehicle is utilized in that operation. Thus the familiar continuous-wave radar speed measurement may depend on response from an uncertain portion of the vehicle; yet an indication of excess speed may be stored until later when, jointly with detection of the speeding vehicle rear, the speed gaging and the vehicle-rear detecting devices may trip the photographic apparatus. Here the speed gaging is not delayed until the vehicle rear is detected, as in the first three embodiments. Such a system is detailed below, in which reference is made to Fig. 4.

In Fig. 4, pneumatic hoses 316 and 318 (employing the 300-series numerals where possible to denote corresponding components in Fig. I) operate pressure-actuated switches 316a and 318a, here responsive to the front wheels of an approaching vehicle 310. Closing of contacts 316a causes a pulse to be generated by components 324, 326, 323 and 332 suitable to trigger timer 336 into operation to close contacts 34012 for a predetermined period of time. The parts of the timer and their operation are the same as those of timer 36 in Fig. l and need not be repeated here. Sufiice it to note that the time that contacts 34% remain closed corresponds to the minimum permissible time it should take a properly operated vehicle to travel from hose 316 to hose 318.

It might be possible for a second set of wheels to close contacts 316a, and apply a pulse to timer 336 so as to extend the timing interval and erroneously indicate excess speed where a vehicle actually travelled at a reasonable and proper speed. The apparatus of Fig. 4 utilizes a vehicle-detector to suppress renewed transmission of pulses to timer 335. This detector 352 as illustrated takes the form and operates like the detector of Fig. 2,

there used to detect the vehicle rear to initiate timer operation and here used for both the detection of the vehicle rear and for suppressing multiple pulse trans mission to the timer. This latter function could be omitted it photocells replaced pressure-actuated switches 316a and 313a. Detector 3S2 incorporates normally closed contacts 358b, closed when the bridge is balanced, when the impedance between wires 316i? and 3180 is undisturbed by the presence of a vehicle. When this impedance is sufiiciently disturbed to unbalance the bridge, contacts 358k open; and thereafter, so long as a vehicle is present, repeated operation of contacts 316a is ineffectual. The positioning of hoses 316 and wires 3160 and 3180 9 is adjusted for this result, taking into account the proportions of vehicles to be detected.

'Whentimer 336 holds contacts 134% closed in response to the front vehicle wheels engaging hose 316, the front wheels may cause contacts 318a to close. If the vehicle is traveling at excessive speed, thiswill occur, whereupon relay 3130' would be energized power supply 318b through contacts 349i; and 318a in series. It will be recalled that at this time, due to bridge unbalance relay 358a is energized. This closes contacts 350 corresponding to contacts'SlB in Fig. 2; but here contacts 350 do not initiate timer operation but complete a stick or holding circuit for relay 31% once that has been energized by closmg of contacts 318a While timer contacts 340!) are closed.

The holding circuit includes supply 318b, contacts 350 and relay holding contacts 318d, in series in addition to,

the relay itself. Thus the gaged result of excess speed is stored. V I

The storage continues until the rear of the vehicle has advanced so that it is in the range of the photographic apparatus previously described. When the impedance between wires 3160 and 3180 has been restored sufiiciently to rebalance bridge 352, contacts 350 open, deenergizing relay 3180. Contacts 318e of this relay close, to trigger a pulse generator 370 to momentarily energize camera tripper 32th: and, with it, the whole camera an strobe lighting equipment; I I

Renewed opening and closing is requiredbefore renewed camera operation can ensue; and before this can take place the speedgaging means including elements 316, 318 and 336 must again reveal excessive speed, this indication must be stored and the stored speed indication must be cleared by detection of the vehicle rear by device 352 which so responds. remains closed, repeated operation of contacts318a is of noconcern. Operation of contacts 3 18a after timer contacts 34% have opened is equally ineffectual despite subsequent detection by elements 316,318 and 352 of the rear of the vehicle. Thus the vehicle-rear detector and the speed gaging means act jointly to open contacts 318:: and thereafter closethose contacts, thereby to energize the camera tripper, but only in response to vehicles speeding at excessive rate.

As a matter of terminology, each of the foregoing embodiments is seen to include elements that are disposed for sensing a vehicle in the t'raflic lane approaching the 'field of the camera. Thus, in Fig. 1 elements 14-'-14a, "1'616a and 1818a sense the vehicle. In Fig. 2 elements 114115116a sense'the vehicle as do elements 116a and 118a individually. In Fig. 3 each of the photocellsconstitute vehicle sensing means. In Fig. 4 elements So long as the holding circuit 316316a and 3183.18a sense the vehicles as do elements 31603180. Further, each of the vehicle-rear detectors in Eigs. 1-4 are changed toyonecondition by the approach of a vehi'cle "into sensing range and the vehicle-rear detectors are reversely changed {to another condition uponpassing of thevehicle, the latter change being utilized herein for control purposes. In Fig. 1 a *carupsetting balance of the counters signals its passing "by restoringthe counters to balance, which restoration,

without more, effects the desired control. In Figs. land 4, the impedance changes due to acarthat enters the detection zone, andthe reverse change is utilized for the desired control, as is true, too, of photocell 218 in Fig. 3. The foregoing embodimentsof my inventionare highly clfectivejn providing photographic evidence against speeding cars, trucks, etc. ,It is especially desirable in some communities where speeding trailer trucks .are regarded outstandingly hazardous that evidence be ob- "tained reliably, irrespective of the length of thevehicle.

It is especially here that the invention disclosed is irri- -portant. Strobe lighting can be usedin photographing the rear end of a truck withoutfear of blinding the driver; zan'cliwith such lighting the license plates willbe revealed 11) at all times, and shadows often cast by 'tailboards and-the like will be eliminated. Strobe lighting is eifective to record sharp pictures because of its inherent brief lighting pulse; and because of its high intensity, comparatively slow color film can be used, greatly aiding identification of the license plate, particularly as to state of origin.

The foregoing illustrative disclosure of my invention in various aspects includes subcombinations that may be readily applied for a variety of purposes; and the systems illustrated are manifestly subject to a variety of substitutions and rearrangement. Therefore the appended claims should be accorded due latitude of interpretation, consistent with the spirit and scope of my invention.

What I claim is:

1. A'photographic speedmonitor, including an electrically-actuated camera and a strobe lighting device synchronized therewith and directed at a particular re gion in a traific lane, a speed detector having sensing means disposed to respond to vehicles approaching said region, said speed detector being differently responsive to vehicles traveling above a predetermined speed and those traveling below that predetermined speed, the speeddetector being in control relation to said camera and effective to actuate said camera in response to vehicles traveling at any speed above said predetermined speed, and vehiclerear detecting means controlling said speed detector to suppress operation thereof until the respective rear ends of the vehicles approaching such region have reached a certain location in said lane adjacent to and in advance of said particular region, said vehicle-rear detecting means including vehicle-sensing means in control thereof and disposed to be effective in said lane in advance of said particular region, said vehicle rear detecting means being changed from one condition while a vehicle is present in the region of the sensing means thereof to another condition as the vehicle passes that sensing region and being thereupon operative to 'end the suppression of the 1 speed detector operation.

2. A photographic speed monitor, including electrically actuated photographic apparatus directed at a particular region in a traffic lane, a speed detector including vehiclesensing means in control thereof and disposed to be ef- 'fective in a zone of that lane at the approach side of and close to said particular region, said speed detector being differently responsive to a vehicle traveling above a predetermined speed and to a vehicle traveling slower than that predetermined speed, a detector uniquely responsive to the rear of a vehicle and including vehiclesensing means in control thereof and disposed to be effective in a' zone of that lane at the approach side of and close to said region, said vehicle-rear detector including means changedin one manner upon approach of a vehicle to the sensing means thereof, and changed in the reverse manner upon passage of said vehicle and being effective thereupon to produce control output and actuating means for said photographic apparatus rendered operative and controlled by output from said detectors in response to a traveling above a predetermined speed and to a vehicle traveling below that predetermined speed, said vehiclerear detector responding differently to a vehicle as it enters, and as it departs from the portion of the trafiic lane at which the vehicle-sensing means thereof is efiective, and a camera and strobe lighting device directed at the end of said restricted portion of said lane and being connected in controlled relation to and controlled by both said vehicle speed detector and said vehicle-rear detector and rendered operative in response to the passing-of a vehiete 11 through said restricted portion of said traflic lane that traveled therethrough above the predetermined speed.

4.. A photographic speed monitor, including electrically actuated photographic apparatus directed at a particular region in a traffic lane, a vehicle speed detector and a vehicle-rear detector disposed to be effective in a portion of the lane immediately preceding said region, said vehicle speed detector responding in one manner to a vehicle traveling below a predetermined speed and responding in a different manner to a vehicle traveling in excess of that speed, said vehicle-rear detector including means responding in one manner upon approach of a vehicle thereto and responding in a different manner as that vehicle departs, and actuating means for said photographic apparatus operatively connected to and controlled by both said detectors to cause operation of said apparatus as the result of and immediately after the latter responses of both of said detectors to a passing vehicle traveling at a speed in excess of said predetermined speed.

5. Photographic speed monitoring apparatus, including a localized vehicle speed detector normally inoperative but adapted to be rendered operative in a confined region along a trafiic lane, a camera connected to said speed detector for control thereby, said camera being directed at a location in said traflic lane adjacent said confined region and further along said lane in the normal direction of traffic, and vehicle-rear detecting means connected in control relation to said speed detector, said vehicle-rear detecting means including vehicle-responsive means, said vehicle-rear detecting means being changed from a first to a second condition by the proximity of a vehicle to said vehicle-responsive means and being reversely changed to the first condition as the vehicle leaves said vehicle-responsive means, said normally inoperative speed detector being coupled to said vehicle-responsive means and rendered operative by said reverse change.

6. In combination, a camera directed at a particular region in a trafiic lane, and vehicle-responsive control means connected in control relation thereto, said vehicle- .responsive means including vehicle sensing means installed in said lane in advance of said particular region and adjacent thereto and electrical means controlled by said sensing means and changed from a first condition to a second condition when a vehicle is sensed by said sensing means, and said electrical means being reversely changed to said first condition when the rear of a vehicle passes said sensing means, said electrical means being adapted to control said camera only in response to the latter change.

7. The combination in accordance with claim wherein said vehicle-responsive means embodies an electrical impedance detector.

8. Apparatus in accordance with claim 5 wherein said vehicleresponsive means includes two successive pressure operated switches, counters actuated by said two switches respectively and means effective to initiate operation of said speed detector as soon as the counter operated by the second switch registers the same count as the counter operated by the first switch.

9. Electrically actuated photographic apparatus directed at a particular region in a trafiic lane, in combination with a speed detector effective in a zone of the lane to gage speed of a vehicle passing along said lane, a device uniquely responsive to the rear of the vehicle in proximity to the speed gaging zone, said device including vehicleresponsive means changed in one manner upon approach of a vehicle thereto and changed reversely upon passage of said vehicle and being adapted to produce control output as an incident of the latter change, and means jointly controlled by said speed detector and by said vehicle-rear responsive device to actuate said photographic apparatus at the moment the rear of a vehicle passing at excess speed reaches said region.

10. Apparatus in accordance with claim 9, wherein ,said speed gaging detector is initiated in operation by the passing vehicle independently of said vehicle-rear responsive device, and wherein means is provided for storing indication of excess speed under control of said speed gaging detector until the rear of the vehicle has reached said particular region as evidenced by response of the vehiclerear responsive device.

11. Apparatus in accordance with claim 9 wherein sald vehicle responsive device embodies an impedance-change detector effective in the traffic lane.

12. A camera and a strobe lighting unit synchronized therewith and both directed obliquely at the rear of vehicles passing a detection region in a traffic lane, first and second photocells disposed in succession along the lane in the detection region, a timer initiated in operation in response to the change in the first photocell only from dark to light, and camera tripping means jointly controlled by said timer and by said second photocell, said camera tripping means being responsive to said second photocell for such control only upon change from dark to light.

13. An electrically actuated camera directed at a particular region in a traffic lane, in combination with means for actuating said camera, and means controlling said camera actuating means, said controlling means including a pair of pressure-actuated switches in said lane ahead of said region with respect to the normal direction of vehicles travelling along said trafiic lane, said pressure-actuated switches being located at positions spaced apart along the lane by a distance greater'than the maximum spacing between the axles of the vehicles in said lane to be photographed, a pair of counters connected to said switches, respectively, to be advanced thereby, and said controlling team having means to detect coincidence of the counters and said controlling means, said means to detect coincidence being connected in control relation to said camera actuating means.

14. In combination, means for detecting vehicles traveling at excessive speed through a limited region of a traffic lane, a camera operatively connected to said means and controlled thereby and directed at a location in said traffic lane beyond said limited region, control means connected in control relation to said speed detecting means including vehicle responsive means, said control means being changed from a first to a second condition by proximity of a vehicle to said vehicle responsive means and reversely change to the first condition upon departure of the vehicle from said proximity, said control means being arranged to render said speed detecting means operative in response to said reverse change.

15. In combination, a camera directed at a location in a traffic lane, actuating means connected in control relation to said camera selectively responsive to vehicles in ,saidllane to cause operation of the camera to photograph only certain vehicles reaching said location, said actuatingfmeans including a speed detector, and control .means connected in control relation to actuating means including'mans responsive to both the front and the rear of each vehicle traveling along said lane, said control means embodying a portion changed from a first condition to a second condition by response of said vehicle front and rear responsive means to the front of a vehicle and said portion being changed reversely to said first condition by response of said vehicle front and rear responsive means to therear of a vehicle, said control means being thereupon effective to enable operation of said selectively responsive camera actuating means in dependence upon determination by said speed detector of excess speed of 16. A photographic speed monitor in-accordance with claim 2, including at least one electrical vehicle-responsive element installed in the trafiic lane and connected as a sensing element in common to. both the vehicle-sensing means of the speeddetector and the-vehicle-sensing means .of the vehicle-rear detector.

p 17. Apparatus in accordance with claim 15, wherein 13 said vehicle front and rear responsive means includes a pair of wheel-pressure actuated switches spaced apart along said lane by a distance larger thanthat of the frontto-rear separation of wheels of vehicles to be photographed.

18. Apparatus in accordance with claim 17 wherein said portion of said control means includes a pair of counters responsive respectively to said wheel-pressure actuated switches, and comparison means connected to said counters and signalling equal advance of the counters for enabling operation of said selectively responsive camera-actuating means.

19. Apparatus in accordance with claim 18, wherein said last named means includes an elapsed-time gating device initiated in operation by said comparison means and an additional pressure-actuated switch connected to and operative for producing a final control signal to said thereto as compared to the impedance magnitude thereof in the absence of a vehicle, and wherein said electrical means includes an impedance measuring bridge having said electrical. conductors connected thereto as an arm thereof, and wherein said first condition is bridge balance and said second condition is bridge unbalance.

21. The combination'in accordance with claim 6, wherein said vehicle sensing means includes a photocell connected to said electrical means and is installed in the traflic lane so as to be exposed to light from above, and wherein said electrical means is in said first condition when said photocell is unobstructed and is changed to said second condition when said photocell is obstructed by. a vehicle.

elapsed time gating device, said additional switch being disposed between said location in said trafiic lane and said pair of pressure-actuated switches.

20. The combination in accordance with claim 6 where- 7 References Cited in the file of this patent UNITED STATES PATENTS

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3058109 *Aug 4, 1958Oct 9, 1962Robot Berning Und CoSpeed detecting methods and arrangements
US3060434 *Feb 25, 1959Oct 23, 1962Agfa AgMethod and apparatus for traffic surveillance
US3120992 *Jun 16, 1960Feb 11, 1964Lee Hollingsworth RAutomobile traffic surveillance apparatus and speed measurement equipment
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US20120154239 *Dec 15, 2010Jun 21, 2012Bridgewave Communications, Inc.Millimeter wave radio assembly with a compact antenna
U.S. Classification396/452, 346/33.00R, 340/937, 346/40, 324/180, 346/33.00D, 340/940
International ClassificationG03B15/00, G01P3/68
Cooperative ClassificationG01P3/68, G03B15/00
European ClassificationG03B15/00, G01P3/68