US3895345A - Traffic signal apparatus - Google Patents

Abstract

A traffic signal for controlling vehicular traffic and typically having red, yellow and green signal lights therein, is provided with an additional signal light, in the form of a circular type strobe light, which is centrally disposed in front of one or more of the signal lights. Electronic control circuitry is provided for initiating operation of the strobe light when the signal light associated therewith is illuminated including when the lamp in the associated signal light fails to function.

Description

United States Patent [191 Elvers et al.

[4 1 July 15, 1975 1 1 TRAFFIC SIGNAL APPARATUS [75] Inventors: Carl L. Elvers; Ralph A. Elvers,

both of Indianapolis, Ind.

[73] Assignee: Belmar Electronics Corporation,

Tampa, Fla.

[22] Filed: Aug. 2, 1973 [21] Appl. No: 384,810

[52] US. Cl 340/41 R; 340/105; 340/331 [51] Int. Cl G083 1/07 [58] Field of Search 340/41, 42, 43, 105, 103, 340/44 [56] References Cited UNITED STATES PATENTS 1,988,555 1/1935 Harase 340/105 2,078,573 4/1937 Johnson 340/105 2,096,952 10/1937 Baker 340/42 3,076,178 H1963 Hastings 340/44 3,529,287 9/1970 Southerland l 340/43 3,564,495 2/1971 Gould 340/44 3,688,259 3/1972 Rebillt 340/105 Primary Examiner-Thomas B Habecker Attorney, Agent, or FirmTrask, Jenkins & Hanley [57] ABSTRACT A traffic signal for controlling vehicular traffic and typically having red, yellow and green signal lights therein, is provided with an additional signal light, in the form of a circular type strobe light, which is centrally disposed in front of one or more of the signal lights. Electronic control circuitry is provided for initiating operation of the strobe light when the signal light associated therewith is illuminated including when the lamp in the associated signal light fails to function.

2 Claims, 5 Drawing Figures PATEHTEnJuL 15 ms SHEET ATFNTF JJ 15 SEEL:

STROBE 94 TRAFFIC SIGNAL APPARATUS BACKGROUND OF THE INVENTION This invention relates to a traffic signal of the variety having red, yellow and green signal lamps mounted therein for controlling vehicular traffic on streets and highways.

Conventionally, vehicular traffic is controlled through the use of traffic signals having a red signal light for stopping traffic, an amber light for indicating a caution condition and a green signal light for allowing traffic to proceed. Of these lights, the observance of the red signal is perhaps the more important, as it is imperative for safe highway conditions that the red signal and its indicated action be observed. The red light, however, has several disadvantages which make its use in urban areas less than satisfactory.

More specifically, it is known that everyone, due to the physiological construction of the human eye, is color blind to the color red when the eye is directed in a normal straight ahead viewing line, and the color red is presented to the eye from an angle of greater than about with respect to the straight ahead viewing line. Therefore. if the attention of a driver of a vehicle is diverted as he approaches an intersection having a traffic signal, there is the distinct possibility that the red signal light will not been seen at the required time or will go completely unnoticed due to the drivers angle of attention. Secondly, some cities are now using high energy street lights, such as of the Lumilux variety, which yield an orange glow over the lighted area and which tend to negate the red color of a traffic signal when it is viewed in the shaded environment created by such street light. Large numbers of illuminated and brightly colored advertising signs, which are common at, or in the vicinity of, high traffic density intersections, have also bccen found to distract from and even totally negate the effect of a red light and cause its warning to go unheeded.

It is, therefore, particularly desirable to provide a traffic signal wherein the red signal light in that signal has reinforcing means to indicate that a red signal is illuminated and which can be detected at virtually all angles of observation; which is effective in an environment utilizing street lights casting a colored glow over the environment; which can be used to negate the effects of illuminated and brightly colored advertising signs located at proximate locations to the intersection controlled by the traffic signal; and which is, if desired, capable of being added to an existing traffic signal.

SUMMARY OF THE INVENTION In accordance with the invention, a traffic signal is provided wherein at least the red signal portion of the overall device is provided with a brilliantly flashing strobe light positioned on the viewing side thereof and preferably centrally disposed within the viewing area of the red signal portion. The portion of the overall device containing the strobe light can be factory installed during the construction of the overall device, or, in the alternative, can bc installed in an auxillary red signal light housing mounted atop or proximately to an existing traffic signal device to accentuate and draw attention to the red or other signals therein.

A flashing or pulsating of the strobe light can be effected by electronic circuitry concurrently with the illumination of the red signal light, even if the lamp in the red signal is inoperative. The electronic control circuitry for the pulsating strobe light can be controlled by the standard timing mechanism associated with the traffic signal to initiate operation of the strobe each time the red or other signal light with which it is associated is illuminated.

The brilliantly flashing strobe light has been found to provide somewhat of an irritant to the human eye so that when the red light is illuminated, and the strobe light is pulsating or flashing, attention of vehicle operators are drawn to focus on the red light which appears to surround the centrally disposed strobe light. The light emitted by the strobe has also been found capable of being peripherally detected up to an angle of taken with respect to a straight ahead viewing line, and, thereby compensates for the color blindness to the color red which is incurred when the red light is peripherally viewed at an angle of greater than about 20 with respect to the same straight ahead viewing line.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the invention and, by way of example, show a preferred embodiment. In such drawings:

FIG. 1 is a front view, taken in perspective, of a conventional three light traffic signal;

FIG. 2 is a perspective view, in exploded form, showing a signal light embodying the invention;

FIG. 3 is a front view of the strobe housing of FIG. 2 showing a strobe light mounted therein;

FIG. 3a is a front view of the strobe housing showing an alternate configuration of strobe light and mounting; and

FIG. 4 is an electronic circuit diagram ofa circuit for operatively controlling a signal light and a strobe light.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The traffic signal shown in the accompanying drawings is for the effective and safe control of vehicular traffic, especially in an intersection with a high number of intersecting highways. or where such area is environmentally illuminated at night with Lumilux lighting, or in an area having a high concentration of illuminated or brightly colored advertising signs immediately adjacent the intersection. The high intensity Lumilux type street lighting has been used in urban areas to reduce the possibility of crime incidence in such areas which would be encouraged and aided by poor lighting. Although such lighting does provide a more adequate illumination of the surrounding environment, a somewhat detrimental effect of it is to cast an amber or orangish glow. These amber tones have been found to cancel out the red of traffic signals in the proximate area thereto, thereby causing such signals to go unnoticed.

The present invention can be incorporated into a standard three-way traffic signal housing which is illustrated in FIG. 1. The signal 10 is comprised of three sub-parts l2, l4, and 16 which are integrated by a singular housing 18. Typically, the top sub-part 12 contains a red lens 20, the middle sub-part 14 an amber lens 22, and the bottom sub-part 16 a green lens 24. Access doors 26, 28 and 30 on the respective sub-parts 12, I4 and 16 of the signal 10 provide access to the respective signal lamps (not shown in FIG. 1) and the various electrical apparatus therefor. These access doors 26, 28 and 30 can be swung open on individual hinges 32 for repair and maintenance of the enclosed apparatus, and are held in their closed position by single turn fasteners (not shown).

The assembly and apparatus showing the inclusion of the inventive assembly is best seen in FIG. 2, wherein one of the sub-part signal units l2, l4 and 16 is shown. It should be understood that the inventive assembly can be incorporated into any one or all of the aforementioned sub-part units l2, l4 and 16. However, it has been found preferable to include the inventive assembly in the red signal sub-unit 12 to overcome the above discussed inherent problems associated with the use of red signals for traffic control.

For the purpose of facilitating the description. only the apparatus used in the top signal unit 12, i.e., the red signal, of the three sub-part signal shown in HO. 1 will be described with reference to P10. 2. The primary signalling device within the signal unit 12 is a conventional signalling bulb 42. The bulb 42 is enclosed by a hyperbolic reflector 44 which surrounds the signalling bulb 42 to increase the intensity of and direct the light from the signalling bulb 42 through the red lens to ward the front of the signal unit 12. A retaining flange 46 is provided around the forward perimeter of the hyperbolic reflector 44 for mounting the red lens 20. The lens 20 is retained in the reflector flange 46 by retaining spring clips 48.

The rearward end 50 of the hyperbolic reflector 44 is securely fitted. as by screw threads. into the face of a light socket 52 which also receives conventional screw threads 54 on the signal lamp 42. The signal lamp 42 is screwed into the socket 52 and, by means of electrical conductors 56 and 58 leading to the socket. receives the energizing voltage at the appropriate time.

The hyperbolic reflector 44. the lamp 42 and the socket 52 therefor. form a unitary assembly which is mounted in a supporting and swingable ring member 60 which has a circumferential groove 62 in the forward face thereof into which a mating edge or flange 64, formed in the outer and rearwardly extending periph cry of the reflector 44, snugly fits. Epoxy resin or the like can be used to further secure the reflector edge 64 in the supporting groove 62. The supporting ring 60 has an upright portion 66 formed on one side thereof. The upper and lower ends of this upright member 66 are re duced in diameter to form mounting pins 68 which are swingably received in mounting brackets 70 which are secured to the internal sides of the top and bottom of the unit housing 12. In this manner. the entire light and reflector assembly can be swung outwardly to provide access to the internally located electronic control circuitry for the device.

The above described apparatus is enclosed in the housing 12 and sealed therein by the front door 26 of the unit which itself is comprised of a door portion 72 having a circular hole 74 therethrough and which is surrounded by a mounting flange 76. The door portion 72 has two projections 78 extending from one side thereof and each of which have a pin 80 protruding therefrom. The pins 80 are swing-ably received in supporting flanges 82 to form and comprise the hinges 32. A sealing gasket 84 is provided around the outer face 86 of the housing 12 to provide a tight seal against such face 86 when the front door 26 is held in its closed position by a single turn threaded fastener 88 which acts against a bifurcated locking member 90 formed as an integral part of the door 26 on the side opposite to that of the supporting pins 80.

A strobe housing 92 is mounted on the mounting flange 76 on the front of the door 26. This housing 92 contains and supports a circular strobe light 94 and a clear lens 96. A gasket 98 is interposed between the rim 100 of the clear lens 96 and the interior side of a radial flange 102 formed and radially extending from the periphery of the front of the strobe housing 92. The lens 96 and gasket 98 are held in place against this flange 102 by appropriate means such as clips 104. The strobe light housing 92 is fastened tightly to the exterior side of the door flange 76 to provide a weather proof encasement for the strobe light 94.

As best seen in FlG. 3, the strobe light 94 is centrally suspended within the strobe housing 92 by three Teflon filaments 106 which can be wrapped around the strobe 94 in the appropriate arcuate position or, can be attached to Teflon collars 108 for connecting the strands 106 to the strobe light 94. The outer ends of the fil3 ments 106 are securedly fastened in holes 110 formed in the strobe housing 92. The Teflon filaments 106 provide adequate support for the strobe light 94, yet do not interrupt the rays of the red signal light which must pass therethrough.

The Teflon filaments 106 can be replaced with ap propriate thin wires which can be interrupted by springs for providing a shock absorbing quality to the strobe light supports to prevent unnecessary shock to the strobe light 94 during high winds which would jolt the overall signal light 10.

Energizing voltage for the gas, desirably Xenon, in the strobe light 94 is applied by input conductors 112 and 114 leading to the light 94. The strobe light will only be illuminated when a grid wire 116. which is wound externally around the light 94. is triggered or energized by means of an energizing conductor 118 which is electrically connected to the grid wire 116. The three electrical conductors 112. 114 and 118 for the strobe light 94 extend generally axially outward from the strobe light into the sub-unit housing 12 where they are conveniently secured to a terminal block 120 along with the two conductors 56 and 58 from the primary signal lamp socket 52. Electrical connections can then be made from a control circuit board 122 to the terminal block 120 for providing energizing voltage for the main signal lamp 42 and the requisite pulsating signal voltage for the strobe 94 at the appropriate times.

An alternative embodiment of the strobe light and mounting therefor is illustrated in FIG. 3a. in this in stance. the strobe light 95 is linear and is mounted in shock absorbing sockets 97 and 99 which are secured to the interior side of the housing 92. The electrical conductors ill. H4 and 118 can extend into the subunit housing 12 to be secured to the electrical terminal block l2". The strobe light in this embodiment presents a brilliantly flashing line within the observed red light. where the embodiment ofFlG. 3 presents a circular light centrally emanating from the observed red light.

The control circuitry 124 for operating the strobe light 94 is mounted on the control circuit board 122 and is shown in detail in FIG. 4. An alternating current supply voltage is impressed across two input conductors 128 and 130 from a conventional AC power supply [not shown). One of these input conductors l28 is connected to one side of a normally open timed switch 132 which is integral with and forms part of a switching mechanism (not shown) as is conventionally used to operate a traffic signal light. The normally open switch 132 is opened and closed in accordance with a typical manner to change from a red signal, to an amber signal then to a green signal, etc. The input conductors 56 and 58 for the signal light socket 52 are connected between the switch 132 and the other side of the input voltage supply. The remaining portion of the circuitry shown in FIG. 4 is for the control and operation of the strobe light 94.

in general. the strobe light 94 must be supplied with a triggering pulse and a relatively large direct current voltage each time the strobe light is to be illuminated. Alternating current at line voltage is supplied to a pair of diode clamping circuits I34 and 136 when the timed switch 132 is closed. These clamping circuits 134 and 136, which are each comprised of a diode 138 and a capacitor 140 effect a shift in the incoming alternating current wave form so that the wave form has no nega k tive excursions. Two peak rectifiers 142 and 144 are coupled to the diode clamping circuits 134 and 136. respectively, to rectify the now positive wave form. which. in effect provides a DC. voltage across at capacitor 146 and 148 in each of the peak rectifiers 142 and 144. This DC. voltage is equal to twice the amplitude of the line voltage which is impressed across the input conductors I28 and 130.

The output from the peak rectificrs 142 and 144 is taken from the positive side 150 of the capacitor 146 in the first rectifier 142, and from the negative side 152 of the capacitor 148 in the second rectifier 144. It should be seen and understood that the voltage measured across these conductors 150 and 152 is equal to four times the amplitude of the alternating current input voltage.

The positive output conductor [50 is connected to the positive terminal input conductor 112 of the strobe light 94. The second. or negative output conductor 152 is similarly connected to the negative input conductor 114 of the strobe light 94. The voltage thereby impressed across the strobe light 94 is present whenever the timing switch 132 is closed. However, the pulsating illumination of the strobe light 94 must be initiated by the application of a triggering pulse to the triggering conductor 118.

The triggering pulses are supplied by an SCR triggering circuit 154. The anode 156 of an SCR 158 in this circuit is coupled to the positive DC. conductor 150 by a coupling resistor 160. while the cathode 162 of the SCR 158 is connected directly to the negative D.C. conductor 152. The SCR. which is normally in a non conductive state. is turned on by the application of a sufficient level of voltage to its gate electrode 164 through a diac 166. A resistor 168 and a charging capacitor I70 determine the firing rate for the SCR according to their combined R.C. time constant. Charging voltage is supplied to the RC. network through a coupling resistor 172 which is connected to the anode 156 of the SCR. When the capacitor has charged to a sufficient voltage level, such voltage being available at the gate electrode 164 of the SCR 158, the SCR is rendered conductive and provides a short circuit from the negative potential line 152 to a capacitor 176 which is coupled between the SCR anode 156 and one side of the primary winding 178 of a transformer 180. The other side of the primary winding 178 is connected to the negative potential line 152. The conductive state of the SCR 158 rapidly discharges the capacitor 176 and collapses the voltage impressed across the primary winding 178 of the transformer 180. This rapid change of voltage in the primary winding 178 induces a large pulse of current in the secondary winding 182 of the transformer 180. This pulse is thereby communicated to the triggering conductor 118 of the strobe light 94, as the conductor 118 is connected to one side of the transformer secondary winding 182.

The triggering pulses are very short in duration, e.g.. on the order of one thousandth ofa second. It has been found more desirable for traffic control to effect a triggering frequency of approximately 60 times a minute. The resulting short duration. 1 hertz triggering of the strobe light )4 creates a high intensity flashing of the strobe. on the order of one million candle power. which, when disposed in front of the red signal light 42, has been found to provide a highly effective and safe traffic controlling apparatus. lt is believed that the flashing of the strobe. which from a distance is viewed as emanating from the center of the red signal light or in the alternative. as a line across the signal light. draws the attention of the drivers of approaching vehicles to focus upon the red light, thereby ensuring its observance.

We claim:

1. An apparatus for controlling vehicular traffic. which comprises a signal light housing a signal light having a reflector a signalling bulb and a lens mounted in said signal light housing. said signalling bulb being interposed between said reflector and said lens, a strobe light housing secured to said signal light housing, a strobe light mounted in said strobe light housing and disposed on the viewing side of said lens. timing means for energizing said signalling bulb. and electronic control circuit means operable by said timing means for operably pulsing said strobe light off and on at a preselected rate when said signalling bulb is energized, said strobe light being generally circular in shape and suspended by a piurality of filaments in a substantially concentric position with respect to the light emitted by said signalling bulb and reflected by said reflector.

2. The apparatus as claimed in claim 1 wherein said filaments for supporting said strobe light are comprised of a light transmitting material.

Claims (2)

1. An apparatus for controlling vehicular traffic, which comprises a signal light housing, a signal light having a reflector, a signalling bulb and a lens mounted in said signal light housing, said signalling bulb being interposed between said reflector and said lens, a strobe light housing secured to said signal light housing, a strobe light mounted in said strobe light housing and disposed on the viewing side of said lens, timing means for energizing said signalling bulb, and electronic control circuit means operable by said timing means for operably pulsing said strobe light off and on at a preselected rate when said signalling bulb is energized, said strobe light being generally circular in shape and suspended by a plurality of filaments in a substantially concentric position with respect to the light emitted by said signalling bulb and reflected by said reflector.

2. The apparatus as claimed in claim 1 wherein said filaments for supporting said strobe light are comprised of a light transmitting material.

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