Abstract:
Apparatus for controlling access of persons, with access lanes adapted for the individual passage of these persons, with readers associated with the access lanes for access authorization and identification and/or blocking means for the persons, characterized in that between two adjacent access lanes ( 2,2 ′) there is provided a control device ( 1 ), which includes—when viewed in the passing direction—the identification and/or blocking means ( 3,3 ′) and the electronic components required for controlling these means, which are located to the left and to the right, respectively.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to an arrangement for controlling access of persons, in particular an arrangement with access lanes adapted for the individual passage of these persons. 
     Such arrangements that control access of persons are known, for example, for ski lifts and aerial tramways, but also for other places providing public access. Arrangements of this type are also used in buildings where access to the building is restricted to a specific group of persons. In most cases, access is provided in the form of access lanes which allow persons to pass one at a time. A barrier device is located inside the access lanes, wherein the barrier device is released after access authorization has been verified. Access authorization may be based on an electronic ticket that does not make physical contact, or on a magnetic card or a card with a bar code. 
     Typically, the barrier devices are implemented as turnstiles. Conventional turnstiles typically include three rods which are offset from each other by 120 degrees and secured to a shaft of the turnstile. Adjacent rods may enclose an acute angle with each other. When a person passes through the turnstile, the shaft is rotated by 120 degrees, so that the rod which originally extended into the passage lane, now lets the person pass, whereas the rod which before pointed towards the person passing through is now in the barrier position. The type of barrier where the rotation axis of the shaft is oriented at an acute angle to the passage plane, is generally referred-to as a turnstile. Turnstiles can adequately control the individual passage of persons, but are frequently viewed as inconvenient. 
     Another type of barrier arrangement includes a shaft which is oriented perpendicular to the passage plane, with the rods rotating in a horizontal plane. This arrangement provides improved comfort over the arrangement described above, but requires a fair amount of space equal to at least the width of a passing lane. 
     To make it easier for persons to pass through the turnstile, the shaft in both arrangements may be rotated by a motor. A turnstile having the first arrangement has been proposed, where the shaft has only a single rod which executes a 360 degree rotation for each passage. Since the drive torque applied by the motor must be small enough so as not to cause bodily injuries, the arrangement with a single rod may not be able to reliably provide access for one person at a time. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to improve an access control arrangement of the type described above by providing more comfort for the user and a reliable access for one person at a time. 
     The invention provides an arrangement for controlling access of persons with access lanes adapted for the passage of these persons one at a time, wherein with each access lane there is associated a turnstile and a reader for access authorization. The turnstile includes a motorized shaft for rotation, wherein the axis of rotation is inclined at an acute angle with respect to the access plane. The shaft includes two rods which are offset relative to the axis of rotation by 180 degrees, for blocking the access lane. A respective one of these rods can be rotated from a blocking position where the rod extends into the passage lane, into a position where the rod points towards the ground in order to let a person pass through. 
     Arrangements of the type described above typically require mechanical and electronic components for each access lane. These components are arranged in separate devices located on the side of the access lanes. Separate additional devices are also required for the blocking means, which are most frequently implemented as turnstiles. Conventional arrangements disadvantageously require considerable space, and their appearance may make the user feel claustrophobic. 
     The invention overcomes these disadvantages by providing a single control device which is located between two adjacent access lanes. The identification and/or blocking means are arranged on the respective left and right side of the control device, as viewed in the passage direction. The control device may include two housing shells which form a floor support and may also receive the identification and/or blocking means. The housing shells may be symmetric and made of cast aluminum. Further advantages of the invention will be discussed below with reference to a specific embodiment. 
     Access is frequently authorized based on an electronic ticket which can operate without making physical contact. Such tickets may include a transponder with a transmitter/receiver which, after activation by an electromagnetic field in a reader, retransmits data. Known readers typically have an antenna formed as an air coil and arranged on the side of the access lane. The coil may also be routed inside a tubular frame. Alternatively, a pan with a plastic lid and made of cast aluminum may be provided. The air coil may then be supported by the plastic lid. 
     The antenna construction of these arrangements, however, is complex and may limit the range at which the tickets can be read. Moreover, the arrangement may make the user feel claustrophobic. 
     The invention overcomes these disadvantages by constructing each antenna—when viewed in the direction of access—of two spaced apart vertical pipes, with an electrically insulating plate extending between the pipes. A conducting loop forming a transmitter/receiver circuit is arranged behind the plate, as viewed from the access direction. This feature provides a sufficient reception range and at the same time may make the user feel less claustrophobic. 
     The tickets can be read reliably from one side by extending between the vertical pipes of the antenna a second plate which is remote from the first plate and at least partially electrically conducting. 
     It is also possible to implement an access control system without employing a turnstile or barrier, for example, for the purpose of statistically sampling the number of persons passing through or for optically indicating when access is authorized. With this type of access terminal, however, adjacent antennas from several access lanes may interfere with each other. 
     It is therefore also an object of the invention to mitigate these problems by providing an access control system that is less complex. 
     According to the invention, an access terminal has at least two antennas for reading RFID transponders without making physical contact with the transponders. The antennas are connected to common transmission/receiving electronics, wherein at any given time only one of the antennas is actively connected to the common transmission/receiving electronics via a multiplexer, while the inactive antennas are shorted, damped or detuned. 
     This approach reduces the complexity of the electronics and has the advantage that different antennas or access lanes no longer interfere with each other. 
     According to another advantageously feature of the invention, the common transmitter/receiver electronics and the antenna are connected in a manner that a short circuit in an antenna is converted into an open circuit at the respective terminal of the transmitter/receiver electronics. The length of the connecting line is preferably equal to one quarter of the wavelength of the selected carrier frequency of the transponder system. 
     The programming logic according to the invention for controlling an access terminal with a plurality of antennas is advantageously designed so that at any given time a multiplexer sequentially connects only one antenna to the transmitter/receiver electronics, with the remaining antennas being shorted or detuned. The multiplexer may actively switch the connected antennas rapidly in sequence, whereby the sequence performed by the multiplexer is halted from the time a transponder is recognized in the reception range of an antenna until the reading process is concluded. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in the following a greater detail with reference to embodiments. 
     The drawing shows in: 
     FIG. 1 a schematic illustration of an arrangement for controlling access of persons, in accordance with the present invention, depicting two access lanes; 
     FIG. 2 a side view of an access control system; 
     FIG. 3 a front view, on an enlarged scale, of the control device; 
     FIG. 4 a top view of an installed turnstile assembly; 
     FIG. 5 a basic block diagram of a multiplexer according to the invention; and 
     FIG. 6 is an electric circuit diagram for implementation of the antenna multiplexer. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 illustrates two adjacent access lanes  2  and  2 ′, each of which has a width of, for example, 55 cm. A central control device  1  which also separates the access lanes  2 , is arranged halfway between the access lanes  2 . A turnstile  3  located in each access lane  2  opens when a valid access authorization is read. Antennas  9  and  9 ′ adapted for receiving data carriers that operate with, for example, contactless chip cards without making physical contact, are located directly on both sides of the access lanes  2  and  2 ′. The control device  1  also includes two read heads facing the access lanes for reading conventional tickets, which may be bar code readers implemented as insertion readers  7  and  7 ′. 
     FIG. 2 illustrates a side view of the access control system, and FIG. 3 shows an enlarged front view of the control device  1 . Two housing shells  4  and  4 ′ made of cast aluminum form the support and also receive the two turnstiles  3  and  3 ′ located to the left and to the right of the control device  1 . A light sensor  5 , which automatically releases the turnstile after reading a valid access authorization of a person wishing to pass through, is disposed in the blocking plane. 
     The shaft  31  of the turnstile is connected to a motor  32  through a transmission and a belt drive  34 . The motor  32  includes an angular encoder  33  so that the motor can be electronically controlled. A motor force can be applied to the shaft  31  to either arrest the shaft  31  in a stop position or to release and advance the shaft  31  by the desired angular position of 180 degrees. The motor control advances the shaft  31  much more smoothly than electromagnetic brakes commonly in use. Each shaft  31  includes two rods  36  which enclose an acute angle and form relative to the rotation axis of the shaft  31 an angle of 180 degrees with respect to each other. In the initial position, one of the rods  36  is positioned in a respective lane  2 , blocking access to the lane. To allow a person to pass through, the shaft  31  is rotated by 180 degrees. In this rotated position, the rod  36  now points towards the ground. This feature provides optimal access and at the same time lessens the possibility for skis, a snowboard, a suitcase and the like, to become caught. 
     The two housing shells  4  and  4 ′ which are made of cast aluminum, form the stand and also receive the two turnstiles  3  and  3 ′ operating on the left and right side, respectively, of the control device  1 . The stand is either securely fastened to the floor or supported for optional height-adjustment by tubes  10 , for example, for winter sports. This feature has considerable advantages and is less demanding, for example, with respect to cabling, site preparation and space requirements. 
     The two shells  4  are terminated at the top by a third shell forming a lid  6 . The lid  6  may be made of plastic and may include a central display  8  for displaying access information, for example, for displaying the ID photos associated with access authorization. 
     FIG. 4 is a top view of an installed turnstile assembly  3 ′ with the lid  6  removed. FIG. 4 also shows a removed turnstile assembly  3  in more detail. A shaft  31  for the blocking rods (not shown) is connected to a motor  32  through a worm gear and a belt drive  34 . An angular encoder  33  is attached to the motor  32 . A motor force which is controlled by a suitable electronic control, holds the blocking rods in a stop position and then releases and rotates the shaft by a desired angle. The motor control advantageously moves the shaft much more smoothly than electromagnetic brakes commonly in use. Although a brake of this type is indicated as component  35 , such a brake can be replaced with a suitable controller for the motor  32 . 
     The operation and technical features of contactless chip cards are described in more detail, for example, in the RFID handbook (Carl Hanser Publishing House, Munich Vienna). Most commonly, a card-shaped electronic ticket stores the authorization data in an EEPROM. Conventional RFID transponders operate at carrier frequencies in the range of 125 kHz and also in the range of 13.56 MHz. In many aspects, the RFID transponders operating at the higher frequency are superior to those operating at lower frequencies and, in particular, provide a higher read-out speed. When the RFID transponder is a subjected to the electromagnetic field of a respective access terminal, the data stored in the transponders may be read out and/or changed. For this purpose, the access terminal includes an antenna in the form of a conducting loop which is connected to a transmitter/receiver electronics. The antenna and the turnstile are associated with a respective access lane. Access terminals of this type without turnstiles or barriers may also be employed, for example, if the number of persons passing through is only to be counted for statistical purposes or in order to visually indicate that access is authorized. Neighboring antennas, however, may disadvantageously interfere with each other. 
     FIG. 5 shows a basic block diagram of a multiplexer according to the invention adapted to control several antennas. A transmitter/receiver electronics  11  is connected to antennas A 1  and A 2  via two lines l 1  and l 2 . These antennas correspond to the antennas  9  and  9 ′ illustrated in FIG.  1 . 
     Each antenna A 1  and A 2  includes at least one coil L 1  and L 2 . The transmitter/receiver electronics  11  produces a radio frequency field with a carrier frequency of, for example, 13.56 MHz, and transmits commands and data to RFID transponders (not shown). Examples of the basic operation of such systems are described in the references cited above. 
     The lines l 1  and l 2  are implemented as coaxial cables with a length corresponding to one quarter of the wavelength of the carrier frequency of the transponder system. 
     Electronic switches S 1  and S 2  which can be actuated via a control input S, are arranged on the lower end of the antennas A 1  and A 2 . At any given time, the control input S can operate one of the switches S 1  and S 2  and activate the antenna A. The other antenna is then shorted and therefore idle. The length selected for the connecting line transforms the short-circuit into an open circuit at the common transmitter/receiver electronics since an open circuit does not affect the operation of the electronics. Consequently, a common transmitter/receiver electronics may operate any number of antennas. Since all the other antennas, with the exception of the active antenna, are shorted, these antennas do no longer interfere with each other. 
     The antennas are activated in rapid sequence by the control input S. When a transponder is identified, the sequence is halted until the transaction (the read/write operation) is concluded. This antenna is reactivated after the person has passed through. 
     FIG. 6 shows an implementation of the antenna multiplexer. The coil L 1  of antenna A 1  is tuned with the help of a capacitor C 1  to a parallel-resonant circuit which is tuned to the carrier frequency. The tuning process can be automated by adding and removing capacitors from the circuit so as to prevent detuning during operation, for example due to changing environmental conditions. 
     Two back-to-back diodes D 1  and D 2  are connected in parallel to the coil L 1 . The center tap of the diodes can be selectively connected through an electronic switch S 1  to a negative auxiliary voltage or to ground. If the diodes are connected to ground, then the coil L 1  is shorted and the antenna is inactive. The respective antenna can then neither send signals to the transponders, nor can neighboring antennas excite resonances in this antenna. 
     If, on the other hand, the switch S 1  connects the diodes D 1  and D 2  to a positive auxiliary voltage, then the diodes are biased in the reverse direction. The antenna A 1  is then activated and can oscillate freely. The positive auxiliary voltage is preferably larger than the open-circuit voltage of the antenna so as not to impede the evaluation of a low-level data signal received from a transponder. 
     The invention can also be applied to systems that process information received from transponders operating at different carrier frequencies. For example, two coils which are tuned to two different frequencies, may be arranged in a single antenna support to enable migration from older transmission systems to newer technologies.