Abstract:
The present invention relates to an improved elevator selector system. One embodiment incorporates all of the operational and A17 code required car position sensing functions into a single car mounted enclosure, without any external mechanical roller switches, by incorporating directional limits, normal terminal slow down and emergency terminal speed limiting functions into a tape selector. All operational and sensing functions may be implemented using a standard 3-inch wide tape by disposing of magnetic signalers on the opposite side of the tape from the side used for leveling and floor identification. An alignment tool facilitates placement of magnets. Tape guides permit the selector to run smoothly along the tape. Optical rather than magnetic sensors may be used for quadrature hole counting to detect relative speed and location without interfering with other magnetic functions. All selector components may be tethered to the selector enclosure to prevent accidental loss down the hoistway. Structural foam and heavy internal gussets may be used for the selector enclosure. Alignment pins on the selector enclosure facilitate component installation. Stress distributing nut plates create a strong interface between the selector enclosure and steel mounting bracket.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 60/314,593, filed Aug. 23, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to elevator systems. More particularly, the invention relates to an improved elevator selector system.  
         BACKGROUND OF THE INVENTION  
         [0003]    Elevator selectors are generally devices used for determining car position. Elevator tape selectors have been in use for several years. However, tape selectors have traditionally not incorporated the terminal back-up systems of directional limits, normal terminal slow-down devices, and emergency terminal speed limiting. Rather, these functions are traditionally performed with mechanical roller switches in the hoistway. Mechanical roller switches are expensive and their assembly and adjustment is labor intensive. Traditionally, to increase the number of functions available on a tape selector, additional tracks are added to the tape, making the tape wider.  
           [0004]    Tape selector housings generally are comprised of fabricated enclosures utilizing many discrete parts, including screws, fasteners, washers, lock washers, plates and circuit boards. Assembly of the large plurality of parts is time-consuming and involves many steps, including shearing, punching, welding, and inserting press nuts. In addition, maintenance of such a selector generally involves the risk of dropping one or more of these parts down the hoistway, thus posing a safety risk and a cost in time and material. Selectors composed of a large plurality of parts also pose a difficulty in proper assembly of the parts during installation and maintenance since the mounting locations are typically in dark, confined and hard-to-reach locations on the car top.  
           [0005]    A typical tape selector using strip magnets often presents potential installation problems with respect to the proper placement and polarity of the magnets. Some selectors are relatively tall in size because of a necessity to isolate certain magnetic functions, like hole counting to determine relative location and speed, from other functions, like floor detection and leveling.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention recognizes the above limitations of prior art elevator selectors and reduces or eliminates these problems. Although the present invention will be described as part of an elevator system, it shall be understood that the improved selector may be employed in other systems requiring position information about a moving cab, carriage, carrier, moving part, etc. In particular, this invention may be applied to other types of elevators or people movers than the type(s) or embodiments described here for purpose of illustration and description of the invention.  
           [0007]    One embodiment of the present invention is an improved tape selector system which incorporates all of the operational and A17 code required car position sensing functions into a single car mounted enclosure, called a selector, without any external mechanical roller switches, by incorporating directional limits, normal terminal slow down and emergency terminal speed limiting functions into a tape selector. The active portions of the functions have been incorporated into a single car mounted enclosure by adding sensors to detect the following signals: Directional Limit Bottom (DLB), Directional Limit Top (DLT), Normal Terminal Slow-down Bottom (NTSB), Normal Terminal Slow-down Top (NTST), emergency Terminal Speed Limiting one (TSL1), emergency Terminal Speed Limiting two (TSL2). The passive portion of the functions has been added to two tracks on the previously unused side of a standard 3-inch wide tape mounted in the hoist-way. By incorporating all of the functions into only two tracks on the previously unused side of the tape, the functions may be added without increasing the size of the tape.  
           [0008]    The additional functions in the improved selector system are implemented with a plurality of appropriately placed north and south polarized magnets distributed along the tape, a plurality of sensors within the selector for detecting the magnets and dynamic real-time decoding. The sensors may be hall effect sensors, and they may be positioned on the back of the circuit board and placed in a hole to improve alignment. The magnets associated with the DLB and DLT functions are arranged in the first track on the previously unused side of the tape, and those associated with the NTSB, NTST, TSL1, and TSL2 are arranged in the second track. Although the NTST, TSL1and TSL2 functions all operate in substantially the same vertical locations and using the same track, NTST functions independently from TSL1and TSL2, as required by the A17 code. An alignment tool facilitates placement of the magnets along the tape.  
           [0009]    Tape guides may be installed between the tape and the main circuit board and auxiliary circuit board to hold the tape and permit the selector to run smoothly along the tape.  
           [0010]    A further improvement involves use of optical rather than magnetic sensors and signals for quadrature hole counting to detect relative speed and location. Optical sensors may be imbedded within the same area without interfering with other magnetic functions. Sequentially-pulsed LED pairs may be used for quadrature hole-count detection to prevent cross talk between adjacent sensors by only having one sensor on at one time. A differential circuit with pass filtration used on the infrared detection circuit to block ambient light and improve detection provides superior performance over the circuits recommended in the prior art for the type of infrared detectors used.  
           [0011]    All selector components, except the tape guides, may be made captive in or tethered to the selector enclosure, thereby improving ease of installation and maintenance by preventing accidental loss down the hoistway. The specific enclosure designed for the selector utilizes structural foam and heavy internal gussets for rigidity to provide lower cost, fewer components, improved performance and consistency over fabricated metal boxes.  
           [0012]    The selector enclosure has alignment pins to facilitate and guide component installation by tactile rather than visual means. Instead of threaded press nut inserts, the selector enclosure has molded cavities which accommodate stress distributing nut plates, which create a stronger interface between the plastic enclosure and steel mounting bracket used to mount the selector on the elevator car with standard bolts. The nut plates are removable and reversible permitting left or right mounting requiring only 2 nut plates instead of 4 nut plates.  
           [0013]    Those skilled in the art will realize that numerous modifications and variations of the present invention are possible in light of the above teachings and embodiments. Therefore, the invention should not be construed as limited to any of the foregoing embodiments, but instead should be viewed within the scope of the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0014]    [0014]FIG. 1 is a front, schematic view of an elevator system in accordance with an embodiment of the invention;  
         [0015]    [0015]FIG. 2 is a perspective view of a selector housing and tape in accordance with an embodiment of the invention;  
         [0016]    [0016]FIG. 3 is a front view of a portion of the elevator guide rail and selector tape together with the selector housing mounted on the car;  
         [0017]    [0017]FIG. 4 a  is a schematic of how the optical hole detection works in accordance with an embodiment of the invention;  
         [0018]    [0018]FIG. 4 b  illustrates quadrature output from the tape hole detection and the phase relationship between the phase “A” and phase “B”;  
         [0019]    [0019]FIG. 5 a  is a schematic of how the optical hole detection works in accordance with an alternative embodiment of the invention in which additional components and logic produce a doubling of the resolution of the hole detection function;  
         [0020]    [0020]FIG. 5 b  illustrates quadrature output from an alternative embodiment of the tape hole detection and the derivation of phase “A” and phase “B” from the “XOR” of Photodiodes A and B, and Photodiodes C and D, respectively;  
         [0021]    [0021]FIG. 6 is a schematic of how the floor identification function is performed;  
         [0022]    [0022]FIG. 7 is a schematic of how the leveling and door zone functions are performed;  
         [0023]    [0023]FIG. 8 is a schematic of how the directional limit detection functions are performed in accordance with an embodiment of the invention;  
         [0024]    [0024]FIG. 9 is a schematic of how the terminal slow-down and speed limiting detection functions are performed in accordance with an embodiment of the invention;  
         [0025]    [0025]FIG. 10 is a schematic showing the car closer to the terminal landing than in FIG. 9 in accordance with an embodiment of the invention;  
         [0026]    [0026]FIG. 11 is a schematic showing the car closer to the terminal landing than in FIG. 10 in accordance with an embodiment of the invention;  
         [0027]    [0027]FIG. 12 is schematic showing the car closer to the terminal landing than in FIG. 11 in accordance with an embodiment of the invention;  
         [0028]    [0028]FIGS. 13 and 14 are front and side views of a selector tape system “T” in accordance with an embodiment of the invention;  
         [0029]    [0029]FIG. 15 is a top plan view of the tape showing the magnet placement in accordance with an embodiment of the invention;  
         [0030]    [0030]FIG. 16 is a front view of a section of the selector tape showing an arrangement of magnets for indicating floor position, leveling and door zone;  
         [0031]    [0031]FIG. 17 is a rear view of a section of the selector tape showing an arrangement of magnets for indication of directional limits and terminal slow-downs according to the invention;  
         [0032]    [0032]FIG. 18 is a schematic of the photodiode detection circuit in accordance with an embodiment of the invention;  
         [0033]    [0033]FIG. 19 is an exploded perspective view from the opposite side of FIG. 2 in accordance with an embodiment of the invention;  
         [0034]    [0034]FIG. 20 shows a perspective view of the relationship between the two printed circuit boards and the tape in accordance with an embodiment of the invention;  
         [0035]    [0035]FIG. 21 shows a front, top and side view of the selector housing and view of one of the alignment pins in accordance with an embodiment of the invention;  
         [0036]    [0036]FIG. 22 shows the selector housing in perspective and one of the internal gussets in accordance with an embodiment of the invention;  
         [0037]    [0037]FIG. 23 shows a front view of one corner of the enclosure housing with one of the corner gussets in accordance with an embodiment of the invention;  
         [0038]    [0038]FIG. 24 shows a front view of one of the cavities used to hold the nut plates according to an embodiment of the invention;  
         [0039]    [0039]FIG. 25 shows one embodiment of the magnet alignment tool;  
         [0040]    [0040]FIG. 26 shows a front view of the alignment tool of FIG. 25; and,  
         [0041]    [0041]FIG. 27 shows an end view of the alignment tool of FIG. 25. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0042]    The features of the invention will now be described in reference to the embodiments described in the Figures. The embodiments described in this invention are intended to be merely exemplary and not limiting in any way. Numerous variations and modifications of the present invention will be readily apparent to those skilled in the art. All such variations and modifications are intended to be within the scope of the present invention as defined in the attached claims.  
         [0043]    [0043]FIG. 1 shows an elevator system that includes a car  10  vertically displaceable in a hoistway  12  between landings. The car  10  is raised and lowered by either a hydraulic jack  14  connected to a pump unit controlled by an elevator control system “C”, or a set of ropes  16  connected to a traction drive system controlled by an elevator control system “C”. The elevator system in FIG. 1 also includes a selector system “S”, which includes a enclosure body member  100  mounted on the car and a tape system “T” mounted in the hoistway and a harness  18  supplying electrical power to and signals from the main printed circuit board within the enclosure body member  100 , also shown in FIGS. 2 and 3. The other end of the harness  18  is connected to the control system via car swing return  20  and traveling cable  22 .  
         [0044]    The selector system “S” provides various signals that are derived from the tape system “T” to the controller. In some embodiments of this system, the controller “C” may be in the machine room and a serial device in the car operating panel  20  receives the signals from the selector system “S” and sends them serially to the controller.  
         [0045]    [0045]FIGS. 4, 5,  6 ,  7 ,  8 , and  9  show schematically the typical relevant signals derived from the tape system and supplied to the controller. In FIG. 4 a  are shown quadrature hole detection signal A, (phase A), quadrature hole detection signal opposite state of A, (phase A NOT), quadrature hole detection signal B, (phase B), quadrature hole detection opposite state of B, (phase B NOT). FIG. 4 b  shows the relationships of the quadrature outputs of phase A and phase B which are approximately 90 electrical degrees apart from each other. FIGS. 5 a  and  5   b  show an alternative embodiment of FIGS. 4 a  and  4   b . In FIG. 6, the floor identification signals are shown, BPP, BP8, BP4, BP2, and BP1. FIG. 7 shows leveling and door zone signals, Level Up, LVU, Level Down, LVD, Door Zone 1, DZ1, Door Zone 2, DZ2. FIG. 8 shows the directional limit signals: Directional Limit Top (DLT) and Directional Limit Bottom (DLB). FIG. 9 shows the terminal slow-down signals, Normal Terminal Slow-down Top (NTST), Normal Terminal Slow-down Bottom (NTSB), emergency Terminal Speed Limiting 1 (TSL1), emergency Terminal Speed Limiting 2 (TSL2).  
         [0046]    In certain embodiments, where the horizontal movement of the car  10  in relation to the hoistway  12  is sufficiently constrained and where continuous car position is not required between floors, hole counting, as shown in FIGS. 4 and 5, may be eliminated and the tape system “T” may be replaced with plates used to hold the magnets at or near each floor, with the enclosure body member modified accordingly.  
         [0047]    [0047]FIGS. 13, 14,  15 ,  16 , and  17  show the tape system “T”. In the particular embodiments shown in FIGS. 13 and 14, the top of tape  300  is attached to bracket  302  which is attached to elevator rail  304 . The bottom of tape  300  is attached to bracket  306  which is spring connected to bracket  308 , which is in turn attached to a bracket  302  attached to the elevator rail  304 . The tape  300  is a 3-inch wide tempered steel tape. FIG. 15 shows a plan sectional view of the steel tape  300  with the magnets. FIG. 16 shows the car side view of the tape and FIG. 17 shows the opposite side. The floor identification magnets  314  through  318  are shown in relation to the leveling magnet  312  as it would be for a single floor with a code that required all of the identification magnets. Different combinations of magnets can be used for different floors.  
         [0048]    In an embodiment of the present invention, the side of the tape opposite the car side, shown in FIG. 17, is used to provide directional limit and normal terminal slow-down and emergency terminal speed limiting functions. The directional limit magnets of  320  at the top and  322  at the bottom generate DLT and DLB signals to operate the directional limit sensors in the selector. These are placed to operate the DLT sensor 1 inch above the floor and the DLB sensor 1 inch below the floor.  
         [0049]    The bottom slow-down magnet  360  is set to operate the appropriate sensors at a distance from the bottom landing dictated by the car speed. The top slow-down magnets  324  through  331 , with additional magnets represented by “etc.” and shown at the top of FIG. 17, are set to operate the appropriate sensors at a distance from the top landing dictated by the car speed. The polarity of magnet  324  is south. The polarity of magnet  325  is north. The polarity of magnet  326  is south. This alternating pattern is continued up the tape until the directional magnet  320  is reached or exceeded. All other magnets on the tape are south pole magnets. The length of magnet  360  extends from the required starting point dictated by the car speed down the tape until the directional limit magnet  322  is reached or exceeded. The length of the directional limit magnets  320  and  322  is sufficient to prevent the car from traveling up past  320  or down past  322 . These distances and magnet locations are where the appropriate selector sensor position is located vertically, when the car is in the referenced location. This feature can also be seen in FIGS. 4 through 9.  
       SELECTOR OPERATION  
       [0050]    Selector Mounting  
         [0051]    As shown in FIG. 3, the enclosure body member  100  is attached to the car via bracket  400  and stile  402 . Stile  402  is part of the sling that holds and is attached to the car  10 . Thus, as the elevator car  10  in FIG. 1 moves up and down the hoistway, so does the enclosure body member  100 . The enclosure body member  100  and its associated sensors surround the tape  100  such that there are sensors on both sides of the tape  100 . Tape guides  104  hold the tape in place to maintain running clearances between the TSM board  101  and the auxiliary assembly  102 . See FIGS. 2, 19 and  20 .  
         [0052]    Optical Tape Hole Counting  
         [0053]    In FIG. 4 a , the holes in the tape  300  are shown interrupting the optical infrared signals from LED “A” and LED “B” to photodiodes “A” and “B”. As the car moves vertically up or down, the holes alternately interrupt, or not, the signals. The phase “A” LED and photodiode “A” are spaced vertically from the “B” LED and photodiode “B” such that the signals as shown in FIG. 4 b  are in quadrature or about 90 electrical degrees apart. These quadrature signals allow the controller “C” to determine the relative position of the car by counting the holes and determine the direction of movement by the quadrature nature of the signals. The logic  130  shown in FIG. 4 a  controls the output of the LEDs “A” and “B” and amplifies, filters, compares and decodes the signals from the photodiodes “A” and “B”. The logic, in this case a field programmable gate array (FPGA), pulses the phase “A” diode with a high current to achieve a high infra red light output, but for a short duration. A pulse of 5 microseconds, used in this case, prevents overheating of the diode.  
         [0054]    The logic  130 , having turned on the LED “A”, also enables an input latch that monitors the photodiode “A”. If, after a suitable waiting period, about 20 microseconds in this case, the latch detects a signal from the photodiode “A”, the logic will record a HIGH for “A”. If the latch does not detect a signal, a LOW will be recorded for “A”. The logic will then repeat the above process for LED “B” and photodiode “B”. These recorded HIGHs or LOWs for the “A” and “B” channels are output at the end of one cycle of an “A” and “B” channel LED pulse and photodiode detection. Then the process will be repeated starting again with the “A” LED and “A” photodiode. The advantage of alternating the “A” and “B” channels is to prevent any cross signals between “A” and “B”. Any stray light from LED “A” that lands on the “B” photodiode is ignored by the logic because the “B” photodiode is not considered during the time the phase “A” LED is on. The reverse is true during the time the “B” LED is on—the “A” photodiode is ignored by the logic. Thus, cross channel interference between “A” and “B” are prevented. As long as the speed or frequency with which the channels are alternated is rapid enough, there is little time-skew or error in the signal between the “A” and “B” channels.  
         [0055]    In another embodiment, it is possible to double the resolution derived from the tape through the use of four LEDs and four photodiodes and additional logic. In this embodiment, shown in FIGS. 5 a ,  5   b , and  5   c , each channel LED is pulsed and the corresponding photodiode is checked, in the sequence of “A”, “B”, “C”, &amp; “D”. The sequence is then repeated. Again, as long as the sequencing is fast enough, there will not be any significant time-skew between channels. The current embodiment is useful to about 350 feet per minute of speed. Photodiode recorded signals “A” &amp; “B” are 90 degrees from each other. Photodiode recorded signals “C” &amp; “D” are 90 degrees from each other, as seen in FIGS. 5 b  and  5   c . The pair “A” &amp; “B” must be 45 degrees from pair “C” &amp; “D”.  
         [0056]    To derive the phase “A” and phase “B” outputs, the “A” and “B” channel photodiode recorded signals in FIGS. 5 b  and  5   c  are Exclusive Ored to form the phase “A” output. The “C” and “D” channel photodiode recorded signals are Exclusive Ored to form the phase “B” output. It must be noted that the hole size on the tape must be such that an accurate 90 degrees phase shift exists between photodiode signals “A” &amp; “B” and “C” &amp; “D”.  
         [0057]    The logic function  130  in FIGS. 4 a  and  5   a  can be implemented in other forms besides an FPGA. Other forms can include software and a microprocessor or in fixed logic. Selector Floor Identification  
         [0058]    In FIG. 6 are shown the floor identification signals. When the car is at a floor, the sensors  131 ,  132 ,  133 ,  134 , and  135  are aligned with the magnet locations  314 ,  315 ,  316 ,  317 , and  318 . If a magnet is in the location, the corresponding sensor will detect it. When the car is level at the floor, the logic FPGA  130  detects this from the signals LVU and LVD and enables the output of the signals BPP, BP8, BP4, BP2, &amp; BP1 to the output drivers and thus to the controller. The particular code used in this embodiment is binary for BP1 through BP8 with the BPP as the ODD parity bit.  
         [0059]    Selector Leveling and Door Zone  
         [0060]    In FIG. 7 is shown the leveling and door zone signals. When the car is at the floor, the sensors  136 ,  137 ,  138 ,  139 ,  140 ,  141 ,  143 ,  143 ,  144 , &amp;  145  detect a leveling magnet  312 . This magnet is 8 inches long in this embodiment. If the car moves off level by going down, then one of the LD1 through LD4 sensors will deactivate. A jumper select selects the particular LED deactivated. This deactivation deactivates the LVD output. The controller will react to this event by raising the car. If the car moves off of level by going up, then one of the LU1 through LU4 sensors will deactivate. A jumper selects the particular sensor. This deactivation deactivates the LVU output. The controller will react to this by lowering the car. This is the continuous relevel function. If the car is stopped for some reason away from the floor, but the leveling magnet  312  activates the selected LVU sensor, the controller will level the car down. If the car is stopped for some reason away from the floor, but the leveling magnet  312  activates the selected LVD sensor, the controller will level the car up. The choice of which LU or LD sensor to use changes the size of the level at the floor zone or the range over which the controller will consider the car level. How large this should be depends on the particular application and drive system.  
         [0061]    In FIG. 7 are also shown the Door Zone sensors  140  and  141 . They detect the leveling magnet  312  and send signals DZ1 and DZ2 to the controller through a driver. The sensors prevent the car door operator from opening the doors if both sensors are not active. In this embodiment, both sensors are active within about 3 inches of level with the floor.  
         [0062]    Selector Directional Limits  
         [0063]    In FIG. 8 are shown the directional limit signals. The top directional limit magnet  320  is placed so that it will activate sensor  146  (DLTH) about one inch above the top landing. The signal from sensor  146  will, through logic  130 , deactivate and turn off relay  162  and drop the signal DLT to the controller. In turn, this will disable the up movement of the car through various controller means. The bottom directional limit magnet  322  is placed so that it will activate sensor  149  about one inch below the bottom landing. The signal from sensor  149  (DLBH) will, through logic  130 , deactivate and turn off relay  163  and drop the signal DLB to the controller. In turn, this will disable the down movement of the car through various controller means. In this embodiment, an additional bi-polar reed switch sensor  147  (DLTR) is near the  146  sensor. This reed switch, when activated, directly removes power from the relay  162  and does not require any active solid-state device to work in order to turn off the relay. This feature is designed to meet certain requirements in the A17 elevator code. In addition, the logic circuit  130  compares the states of sensors  146  and  147 . The magnet  320  activates sensor  146  first and then sensor  147  in an up over travel. If sensor  147  is activated, and sensor  146  is not, this would be an error. This could mean that the  146  sensor is non-functional, or it could mean that the magnet  320  is installed with the north side out. This would activate the bi-polar  147  sensor but not the Hall Effect  146  sensor.  
         [0064]    Also, an additional bi-polar reed switch sensor  148  (DLBR) is near sensor  149 . This reed switch, when activated, directly removes power from the relay  163  and does not require any active solid-state device to work in order to turn off the relay. This is to meet certain requirements in the A17 elevator code. In addition, the logic circuit  130  compares the states of sensors  149  and  148 . The  322  magnet activates sensor  149  first and then sensor  148  in a down over travel. If sensor  148  is activated, and sensor  149  is not, this would be an error. It could mean that the  149  sensor is non-functional, or it could mean that the magnet  322  is installed with the north side out. This would activate the bi-polar  148  sensor but not the Hall Effect  149  sensor. Additional logic is included in  130  that disables the error checking for the  146  and  147  sensors if the  149  sensor is activated and the error checking is disabled for the  148  and  149  sensors if the  146  sensor is activated. This is to prevent a false error when the car is run far past the floor and the magnet  320  activates sensors  148  or  149  or if magnet  322  activates sensors  146  or  147 . Certain special elevator operations can produce such a situation.  
         [0065]    Selector Normal Terminal Slow-Down Bottom, NTSB  
         [0066]    [0066]FIGS. 9, 10,  11 , and  12  show the down direction slow-down portion of the Normal Terminal Slow-down detection function and associated signals, NTSB. It should be noted that these are the back-up slow-downs required at the terminals by the A17 code and not the regular method of slowing the car down. The regular method uses the relative hole count between floors shown in FIGS. 4 and 5, the start the slow-down at a software controlled position count in the hoistway.  
         [0067]    In FIGS. 9, 10,  11 ,  12 , for the down direction near the bottom terminal landing, magnet  360  is in the vertical track for NTSB shown in FIG. 15. A continuous magnet, with a south pole on the face, is the actuating magnet for the down terminal slow-down function. This magnet may be one piece or made-up of smaller magnet pieces and butted end-to-end to form a functionally equivalent contiguous south face along its length. Sensors  150 ,  151 ,  154 ,  157 ,  160  and  161  are the relevant sensors for this function. The signals from these sensors, NTUA, NTUB, NTUC, NTLA, NTLB, NTLC are fed into logic  164  for decoding. Upon appropriate detection of the magnet  360 , the logic will drop signal NTSB, Normal Terminal Slow-down Bottom, to the controller. In turn, this will cause the car to slow-down.  
         [0068]    The appropriate detection decodes for this embodiment are any of four sets of conditions of activated sensors. They are (NTLC plus NTLB plus NTLA) or (NTLB plus NTLA plus NTUC) or (NTLA plus NTUC plus NTUB) or (NTUC plus NTUB plus NTUA). If any of the four sets of three sensors is activated the logic  164  will drop the signal NTSB, Normal Terminal Slow-down Bottom, to the controller. In turn, this will cause the car to slow down. For positive logic signals, this can be represented in Boolean logic form as (not NTSB)=(NTLC and NTLB and NTLA) or (NTLB and NTLA and NTUC) or (NTLA and NTUC and NTUB) or (NTUC and NTUB and NTUA. The logic  164  is a programmable array logic (PAL) device in this embodiment. Other embodiments may use discrete logic or a microprocessor with software to implement this logic function.  
         [0069]    In FIG. 9, for a down run, magnet  360  is shown just activating sensor  157  and also having activated sensors  160  and  161 , these are signals NTLA, NTLB and NTLC respectively. This is one of the logic conditions sufficient for logic  164  to drop NTSB. As the car proceeds toward the bottom landing, magnet  360  moves up in relation to the sensors. In FIG. 10, magnet  360  is shown at a vertical position that would just activate sensor  154  as well as having activated  157 ,  160  and  161 . These sensors provide signals NTUC, NTLA, NTLB, and NTLC, respectively to logic  164  for decoding. This combination of four active signals provides two logic conditions to logic  164 , (NTLC and NTLB and NTLA), and (NTLB and NTLA and NTUC), either one of which is sufficient for the logic  164  to drop NTSB. In FIG. 11, magnet  360  is shown at a vertical position that would just activate sensor  151  as well as having activated  154 ,  157 ,  160  and  161 . These sensors provide signals NTUB, NTUC, NTLA, NTLB, and NTLC, respectively to logic  164  for decoding. This combination of five active signals provides three logic conditions to logic  164 , (NTLC and NTLB and NTLA), (NTLB and NTLA and NTUC), and (NTLA plus NTUC plus NTUB), any one of which is sufficient for the logic  164  to drop NTSB.  
         [0070]    In FIG. 12, magnet  360  is shown at a vertical position that would just activate sensor  150  as well as having activated  151 ,  154 ,  157 ,  160  and  161 . These sensors provide signals NTUA, NTUB, NTUC, NTLA, NTLB, and NTLC, respectively to logic  164  for decoding. This combination of six active signals provides four logic conditions to logic  164 , (NTLC and NTLB and NTLA), (NTLB and NTLA and NTUC), (NTLA plus NTUC plus NTUB), and (NTUC plus NTUB plus NTUA) any one of which is sufficient for the logic  164  to drop NTSB. As the car continues to the bottom landing, the magnet  360  is long enough to keep the sensors active if and until the car goes past the bottom floor and the bottom directional limit DBL is activated.  
         [0071]    The first logic condition is sufficient for proper operation and the single logic condition of (NTLC and NTLB and NTLA) will operate correctly. By utilizing the other three signals of NTUA, NTUB and NTUC, robustness of this function in increased. This improvement is because, for example, a failure of sensor  161  or the loss of signal NTLC would be replaced by the next logic condition of (NTLB and NTLA and NTUC). This is slightly further toward the landing, but a late terminal slow-down is better than a total failure if the one sensor  161  is lost. Thus, utilizing the four logic conditions of (NTLC and NTLB and NTLA) or (NTLB and NTLA and NTUC) or (NTLA and NTUC and NTUB) or (NTUC and NTUB and NTUA) increases the robustness of the function. As a practical matter, in this particular embodiment, the additional sensors required are already in place for use by the up direction terminal slow-down and there is no additional cost to implement the additional logic in the logic device  164  due to its having gates available.  
         [0072]    Selector Normal Terminal Slow-Down Top, NTST  
         [0073]    In FIGS. 9, 10,  11 ,  12 , for the up direction near the top terminal landing, a series of magnets in the vertical track for NTST, shown in FIG. 15, contain the actuating magnets for the slow-down portion of the up Normal Terminal Slow-down function, NTST. This series of magnets start with magnet  324 , with a south polarity on its face. In this embodiment, magnets  324 ,  325 , etc., are 2.5 inches long. Next to and above magnet  324  is magnet  325 . Magnet  325  has a north polarity on its face. Next to and above  325  is magnet  326  with a south polarity on its face. This alternating pattern continues up the hoistway on the tape  300  a sufficient distance for the car to reach the upper directional limit such that the selector sensors detect the DLT signal from magnet  320  in FIG. 8. The relevant actuating magnets for the NTST function are the south faced magnets.  
         [0074]    Like the down terminal limits described above, sensors  150 ,  151 ,  154 ,  157 ,  160  and  161  are the relevant sensors for this function. The signals from these sensors, NTUA, NTUB, NTUC, NTLA, NTLB, NTLC are fed into logic  164  for decoding. Upon appropriate detection of the series of magnets starting with magnet  324 , the logic will drop signal NTST, Normal Terminal Slow-down Top, to the controller. In turn, this will cause the car to slow-down.  
         [0075]    The appropriate detection decodes for this embodiment is any of six sets of conditions of three sensors each. The six sets are (NTUA plus not NTUB plus NTLA) or (NTUA plus not NTUC plus NTLA) or (NTUB plus not NTUC plus NTLB) or (NTUB plus not NTLA plus NTLB) or (NTUC plus not NTLA plus NTLC) or (NTUC plus not NTLB plus NTLC). If any of the six sets of three sensors is in the condition listed above the logic  164  will drop the signal NTST, Normal Terminal Slow-down Top, to the controller. In turn, this will cause the car to slow down. For positive logic signals, this can be represented in Boolean logic form as (not NTST)=(NTUA and (not NTUB) and NTLA) or (NTUA and (not NTUC) and NTLA) or (NTUB and (not NTUC) and NTLB) or (NTUB and (not NTLA) and NTLB) or (NTUC and (not NTLA) and NTLC) or (NTUC and (not NTLB) and NTLC). As stated before, the logic  164  is a PAL device in this embodiment. Other embodiments may use discrete logic or a microprocessor with software to implement this logic function.  
         [0076]    In FIG. 9, for upward movement of the car, the leading edge of magnet  324  is shown just actuating sensor  157 , signal NTLA, and having activated sensor  156 , signal NTUC, magnet  325  is shown as not activating sensor  151 , signal NTUB, magnet and magnet  326  is shown just actuating magnet  150 , signal NTUA. Logically this is NTLA and NTUC and (not NTUB) and NTUA. This meets the criteria of (NTUA and (not NTUB) and NTLA). This is one of the six sets of logical conditions sufficient for logic  164  to drop NTST.  
         [0077]    As the car proceeds toward the top landing, the series of magnets starting with magnet  324  moves down in relation to the sensors. At some point before magnet  324  reaches the point at which it activates sensor  160 , it will still activate  157 , signal NTLA, but will no longer activate  154 , signal NTUC, magnet  325  will still not activate  151 , signal NTUB, and  326  will still activate  150 , signal NTUA. Logically this is NTLA and (not NTUC) and (not NTUB) and NTUA. This meets the criteria of (NTUA and (not NTUB) and NTLA), and it meets the criteria of (NTUA and (not NTUC) and NTLA).  
         [0078]    As the car proceeds further toward the top landing, the series of magnets starting with magnet  324  moves further down in relation to the sensors. In FIG. 10, magnet  324  is shown at a vertical position that would just activate sensor  160 , signal NTLB, as well as having activated  157 , signal NTLA. Magnet  325  does not activate  154 , signal NTUC. Magnet  326  just activates  151 , signal NTUB as well as having activated  150 , NTUA. Logically this signals NTLB, NTLA, (not NTUC), NTUB, and NTUA. This meets criteria (NTUA and (not NTUC) and NTLA) and criteria (NTUB and (not NTUC) and NTLB).  
         [0079]    As the car proceeds toward the top landing, the series of magnets starting with magnet  324  moves down in relation to the sensors. At some point before magnet  324  reaches the point at which it activates sensor  161 , it will still activate  160 , signal NTLB, but will no longer activate  157 , signal NTLA, magnet  325  will still not activate  154 , signal NTUC, magnet  326  will still activate  151 , signal NTUB, but will no longer activate  150 , NTUA. Logically this is NTLB and (not NTLA) and (not NTUC) and NTUB and (not NTUA). This meets criteria (NTUB and (not NTUC) and NTLB) and criteria (NTUB and (not NTLA) and NTLB). The (not NTUA) is ignored at this point.  
         [0080]    Again as the car proceeds further toward the top landing, the series of magnets starting with magnet  324  moves further down in relation to the sensors. In FIG. 11, magnet  324  is shown at a vertical position that would just activate sensor  161 , signal NTLC, as well as having activated  160 , signal NTLB. Magnet  325  does not activate  157 , signal NTLA. Magnet  326  just activates  154 , signal NTUC as well as having activated  151 , NTUB. Logically this is NTLC, NTLB, (not NTLA), NTUC, and NTUB. This meets criteria (NTUB and (not NTLA) and NTLB), criteria (NTUC and (not NTLA) and NTLC).  
         [0081]    As the car continues to proceed toward the top landing, the series of magnets starting with magnet  324  moves down in relation to the sensors. At some point before magnet  326  reaches the point at which it activates sensor  157 , magnet  324  will still activate  161 , signal NTLC, but will no longer activate  160 , signal NTLB, magnet  325  will still not activate  157 , signal NTLA, and will not activate  160 , signal NTLB, magnet  326  will still activate  154 , signal NTUC, magnet  327  will not activate  151 , signal NTUB, and still will not activate  150 , signal NTUA. Logically this is NTLC, (not NTLB), (not NTLA), NTUC, (not NTUB), (not NTUA). This meets criteria (NTUC and (not NTLA) and NTLC) and criteria (NTUC and (not NTLB) and NTLC).  
         [0082]    Then, as the car proceeds further toward the top landing, the series of magnets starting with magnet  324  moves further down in relation to the sensors. In FIG. 12, the series of magnets are shown at a vertical position in which magnet  326  would just activate sensor  157 , signal NTLA, as well as having activated  154 , signal NTUC. Magnet  324  would have activated  161 , signal NTLC, magnet  325  does not activate  160 , signal NTLB. Magnet  327  does not activate  151 , signal NTUB, magnet  328  just activates  150 , signal NTUA. Logically this is NTLA, NTUC, NTLC, (not NTLB), (not NTUB), NTUA. This meets criteria (NTUB and (not NTLA) and NTLB) and criteria (NTUC and (not NTLA) and NTLC) and it also meets the first criteria of (NTUA and (not NTUB) and NTLA). With magnet  326  just activating  157 , and magnet  328  just activating  150 , this is where a repeating cycle of the six criteria starts over again. This cycle will continue up the hoistway until the top directional limit is reached at DLT in FIG. 8. Thus, NTST will be off and the car will be in slow-down in this region where the above criteria are met.  
         [0083]    Selector Emergency Terminal Speed Limiting, TSL1 &amp; TSL2  
         [0084]    [0084]FIGS. 9, 10,  11 , and  12  show the Emergency Terminal Speed Limiting detection and associated signals, TSL1and TSL2. As noted for the Normal Terminal Slow-down, these are the back-up slow-downs required at the terminals by the A17 code and not the regular method of slowing the car down. The regular method uses the relative hole count between floors shown in FIGS. 4 and 5, to start the slow-down at a software controlled position count in the hoistway.  
         [0085]    In FIGS. 9, 10,  11 ,  12 , for the up direction near the top terminal landing, a series of magnets in the vertical track for TSL1 and TSL2, shown in FIG. 15, contain the actuating magnets for the up Emergency Terminal Speed Limiting functions. This function is just a redundant up terminal slow-down like the NTST. This series of magnets starts with magnet  324 , with a south polarity on its face. In this embodiment, magnets  324 ,  325 , Etc. are 2.5 inches long. Next to and above  324  is magnet  325 . Magnet  325  has a north polarity on its face. Next to and above  325  is magnet  326  with a south polarity on its face. This alternating pattern is the same as that used for the NTST function, and continues up the hoistway on the tape  300  a sufficient distance for the car to reach the upper directional limit such that the selector sensors detect the DLT magnet  320  in FIG. 8. The relevant actuating magnets for the TSL1 and TSL2 functions are the north faced magnets.  
         [0086]    Sensors  152 ,  155 , and  158  are the relevant sensors for the TSL1 function. The signals from these sensors are ETA1, ETB1, and ETC1 and are fed into logic  165  for decoding. Sensors  153 ,  156 , and  159  are the relevant sensors for this function. The signals from these sensors are ETA2, ETB2, and ETC2 and are fed into logic  166  for decoding.  
         [0087]    Upon appropriate detection of the series of magnets starting with magnet  325 , the logic  165  will drop signal TSL1 and logic  166  will drop signal TSL2. The TSL1 and TSL2 functions are redundant to each other for the purpose of protection against a single failure. A single failure of one will not prevent the other from functioning.  
         [0088]    The appropriate detection for this embodiment is actuation of any of the three sensors  152 ,  155  or  158  (signals ETA1, ETB1 or ETC1) will cause logic  165  to drop TSL1 to the controller. In turn the car will be slowed down. The actuation of any of the three sensors  153 ,  156  or  159  (signals ETA2, ETB2 or ETC2) will cause logic  166  to drop TSL2 to the controller. In turn the car will be slowed down.  
         [0089]    In FIG. 9, the magnet  325  is shown just actuating  152  as magnet  324  just actuates  157  and magnet  326  just actuates  150 . Thus, TSL1 will be dropped at the same point in the hoistway as the NTST function. Magnet  325  will actuate  153  a very short distance after  152 . This means that at a short distance after NTST and TSL1 are dropped, the TSL2 will be dropped. This distance is 0.2 inches in this embodiment. This distance is functionally insignificant.  
         [0090]    As the car moves up, the magnets move down in relation to the sensors. In FIG. 10 magnet  325  is shown still actuating  152  and  153  and just actuating  155 . Thus TSL1, and TSL2 are still dropped as well as NTST (See the paragraphs on the NTST above for these same figures.)  
         [0091]    [0091]FIG. 11 shows the car moved further up the hoistway. Magnet  325  is no longer actuating  152  or  153 , but still actuating  155  and  156  and just actuating  158 . Again, TSL1, TSL2 and NTST are still dropped.  
         [0092]    [0092]FIG. 12, with the car further up the hoistway, shows magnet  325  no longer actuating  155  and  156  but still actuating  158  and  159 . Magnet  327  is just actuating  152 . Again, TSL1, TSL2, and NTST are still dropped. FIG. 12 shows the start of the repeating of the cycle of the various criteria for the NTST, TSL1, and TSL2. This cycle will continue up the hoistway until the top directional limit is reached at DLT in FIG. 8. Thus, TSL1, and TSL2 will be off and the car will be in slow-down in this region where the above criteria are met.  
         [0093]    It should be noted that the magnets in the series starting with  324  are, in this embodiment, 2.5 inches long. The spacing between the sensors  150 ,  151 ,  154 ,  157 ,  160  and  161  is 1.75 or 1.5 inches. This means that each magnet spans across successive sensors. There is sufficient overlap so that the next logic condition is securely established before the previous logic condition is lost. Thus, the appropriate state of NTST, TSL1 and TSL2 are maintained, even though there are alternating magnet polarity and a corresponding alternating state of the sensors. It is this overlap of the magnet polarity pattern with the sensors that produces the necessary logic states that is key to allowing the Emergency Terminal Speed Limiting function, TSL1, TSL2, to operate in an interlaced manner with the Normal Terminal Slow-down Top, NTST, without one function&#39;s magnets interfering with or potentially operating the other functions sensors. The NTST function uses South faced magnets and the sensors for the NTST function only activate with south faced magnets. The TSL1, and TSL2 functions only activate to north faced magnets. If the north faced magnets were to be removed, without disturbing the south faced magnets, the NTST function would still operate, but the TSL1 and TSL2 would not. In reverse, if only the south faced magnets were removed from the alternating pattern, then the TSL1 and TSL2 function would work but the NTST function would not. Thus, due to the spatially coded alternating magnets, NTST, TSL1, and TSL2 operate in practically the same vertical location of the car selector and in the same track, but with functional independence between the NTST and the TSL1 and TSL2.  
         [0094]    In certain embodiments of the this system, in conjunction with certain embodiments of the car control system, detection of missing or reversed magnets is possible during an initial set-up scan of the hoistway performed by the car control system in which the selector outputs are checked against expected signals along the tape. Missing or reversed magnets will produce missing or incorrect signals. This is in addition to the detection of reversed polarity directional limit magnets (DLT and DLB signals) incorporated into the selector  130  in FIG. 8  
       DETECTION CIRCUIT  
       [0095]    In FIG. 4 a  are shown detection circuits  132  and  134 , and in FIG. 5 a  are shown detection circuits  132 ,  134 ,  136 , and  138 . In FIG. 18 is the schematic of one of the photodiodes and one of the detection circuits ( 132 ,  134 ,  136 , or  138 ) used to detect the holes in the tape. In this circuit, the photodiode PD1 is reversed biased by voltage PD+(2.9 volts) through resistors R1 and R2. Node 1 is connected to node 7 by capacitor C1. C1 and R4 form a high pass filter. Node 2 and node 8 are connected by capacitor C2. C2 and R5 form a high pass filter. D1 through D4 prevent large voltage excursions beyond the comparator&#39;s range to prevent slow recovery due to large ambient light changes. Node 7 and node 8 are close to the center voltage CM0, (1.45 volts) with node 7 pulled up a few millivolts above CM0 by R3, and node 8 pulled down a few millivolts below CM0 by R6. Comparator UIA has an output that is high when node 7 is positive with respect to node  8 .  
         [0096]    When a pulse from an LED shown in FIGS. 4 and 5 sends infrared light through a hole  310  on tape  300  and is received by photodiode PD1, the diode conducts current. It also conducts current due to ambient light. The current involved is very small, typically in the 3-microampere range. Typical circuits recommended for use with photodiodes involve using amplifiers to amplify the current with either a fixed wide dynamic range amplifier or a self-adjusting variable gain amplifier to useful level and then use this high level signal to do detection. In this application, ambient light changes at a relatively low frequency. The LED pulse sent to the photodiode is in the 5-microsecond range. By placing a high pass filter in the form of C1, C2, R4, and R5, direct current and low frequency signals are blocked,, but the high frequency 5 microsecond pulse from the LED is passed. The pulse will cause the photodiode PD1 to increase conduction rapidly. This rapid conduction causes the voltage between node 1 and node 2 to be reduced rapidly. This in turn causes the capacitor C1 to drive node 7 below CM0 and it causes C2 to drive node 8 above CM0. The result is that the pulse causes nodes 7 and 8 to reverse polarity. Comparator UIA detects this and its output goes low. Slowly changing ambient light does not cause the polarity change of nodes 7 and 8 due to the high pass filters of C1, R4 and C2, R5. Unlike amplifier circuits, this circuit works the same over a wide range of ambient light because it only detects the high-speed pulse. The output of the comparator is high or low and thus it is compatible with the digital input the logic circuit  130  requires. Thus, the circuit directly digitizes the analog signal from the photodiode.  
         [0097]    Because this circuit would be subjected to considerable electromagnetic interference (EMI), the circuit is balanced differential and symmetrical about the CM0 point. This fact and a balanced symmetrical printed circuit board layout prevent electrical noise form producing false signals in the circuit.  
       SELECTOR ENCLOSURE  
       [0098]    Captive Components  
         [0099]    [0099]FIG. 19 shows an exploded view of the advantageous new selector enclosure and the various components that attach to it. This view is from the opposite side of FIG. 2. Harness  18  is attached to harness plate  107 . Harness plate  107  is bolted to enclosure body member  100  with screws  110  that go into brass inserts  111  seated in the molded enclosure body member  100 . Tether and ground wire  108  tethers cover  106  to harness plate  107 . Tether and ground wire  109  tethers auxiliary assembly  102  to harness plate  107 . Cover  106  is bolted to enclosure body member  100  with screws  110  that go into brass inserts  111  seated in the molded enclosure body member  100 . The cover  100  and the harness plate have “key-holes”  112  and slots  117  that allow removal of the cover  110  and harness plate  107  without total removal of the screws  110 . Nut plates  105  are captive in the enclosure body member  100  in which a cavity  116  is molded to hold the nut plate  105 . FIG. 24 shows a detail of this cavity  116 . Printed Circuit Board, PCB  103  is part of assembly  102 . Assembly  102 , tape guides  104  and PCB  101  form a sandwich and are bolted to the enclosure body member  100  by thumb screws  115 . Thumb screws  115  mate with brass inserts  114  in the enclosure.  
         [0100]    PCB  101  connects electrically with PCB  103  through a connector set  113  with half the set on  101  and the mating half on  103 . Connectors  118  on PCB  101  mate with receptacles on the harness  18 . Thus it can be seen that all components are, during normal installation and maintenance, attached to prevent dropping them down the hoistway. The exceptions to this are the tape guides  104 . PCB  101 , while not completely captive when assembly  102  is removed for installation, is effectively tethered by the harness  18 . During installation, the assembly  102  is removed and the tape  300  is inserted between the tape guides  104  and between the PCBs  101  and  103 . See FIGS. 19 and 20.  
         [0101]    Printed Circuit Boards  
         [0102]    [0102]FIG. 20 shows PCB  101 . It is the TMS or Tape Selector Main printed circuit board. It contains sensors  131 ,  132 ,  133 ,  134 ,  135 ,  136 ,  137 ,  138 ,  139 ,  140 ,  141 ,  142 ,  143 ,  144 ,  145  that are shown in FIGS. 6 and 7. It also contains the photodiodes shown in FIGS. 4 a  and  5   a . The TSM  101  contains the logic  130 ,  164 ,  165  and  166 , and various other support electronics for this particular embodiment. Also, FIG. 20 shows PCB  103 . It is the TSA or Tape Selector Auxiliary printed circuit board. It contains sensors  146 ,  147 ,  148 ,  149 ,  150 ,  151 ,  152 ,  153 ,  154 ,  155 ,  156 ,  157 ,  158 ,  159 ,  160 ,  161  that are shown in FIGS. 8, 9,  10 ,  11 , and  12 . It also contains a small amount of support electronics for this particular embodiment.  
       SELECTOR ENCLOSURE CONSTRUCTION  
       [0103]    Gussets  
         [0104]    In FIGS. 21, 22, and  23  are shown gussets  119  and  120  that are designed to greatly increase the strength of the enclosure. Though engineering analysis it was determined that the addition of an additional attachment  121  (seen in FIG. 22), for the cover also added to the overall strength of the enclosure. Engineering analysis indicates that this particular embodiment will withstand a 250 lb load applied to the top of the enclosure when the enclosure is made of structural foam injection molded polycarbonate FL900 or equivalent. Advantageous placement and size of the gussets and cover attachments make this a particularly robust embodiment.  
         [0105]    Alignment Pins  
         [0106]    [0106]FIG. 21 shows that the enclosure has alignment pins  121  molded into the front of the enclosure. These pins are an aid during installation and will hold the PCBs  101  and  103  and the tape guides  104  during assembly and during the installation of the tape into the selector enclosure. This allows a tactile installation in places where visibility is poor or nonexistent. The pins  121  go through the PCBs and the tape guides  104 .  
         [0107]    Nut Plates  
         [0108]    [0108]FIG. 19 shows nut plates  105 . The mounting bracket  400  in FIG. 3, used to hold the enclosure body member  100  to the car stile  402 , is bolted to the enclosure through the bracket  400 , through holes  122  in the enclosure and into nut plates  105  in cavities  116 . Instead of nuts or inserts in the plastic enclosure body member  100 , nut plates  105  are used, along with the cavities  116  to provide a means of transferring the load of the enclosure to the mounting bolts without over-stressing the plastic. These nut plates  105 , by being removable, allow two nut plates to be sufficient for right and left hand installations. If an opposite hand is required, the two plates are removed, reversed, and reinstalled on the opposite side. They provide a secure and lower stress method of attachment over regular nuts and bolts or brass inserts in the plastic.  
       ALIGNMENT TOOL  
       [0109]    [0109]FIGS. 25, 26 and  27  show the alignment tool and crevice or slot  500 . When placing magnets on the often difficult to see back side of the tape as shown in FIG. 17, the tool is placed against the tape with the tape edge inside the crevice or slot. The longer lip of the tool, FIG. 27, 501, is used on the back side of the tape. The shorter lip, FIG. 27, 502, is on the front side. With the tool in this position, it is possible to use one hand to both hold to tool and use the fingers of that same hand to pull each magnet edge against the edge of the tool for proper horizontal of the magnets on the back side of the tape. The tool can be slid up on down the tape for complete alignment of the magnets on a particular side of the tape. The tool can then be moved to the other side of the tape to align the magnets on that side. All of this is done tactilely with little or no visibility. The tool&#39;s short lip, FIG. 27, 502, is shorter to prevent interference with the magnets on the front side of the tape.