Abstract:
A low power parking meter to control two or four parking bays. A display, either by a flag-wheel or a digital display will normally indicate the status of each bay. When funds are deposited without indicating the bay to be credited, the meter will escrow the amount until a bay is chosen. The meter normally operates in an idle loop unless an individual bay is being checked or vended.

Description:
CROSS- REFERENCE TO OTHER APPLICATION    
       This application is a continuation - in - part of application  08 / 281 , 700 , filed Jul.  28 ,  1994 , which issued on Dec.  12 ,  1995  as U.S. Pat. No.  5 , 475 , 373  and which itself is a divisional of application Ser. No.  07 / 864 , 479 , filed Apr.  7 ,  1992 , which issued as U.S. Pat. No.  5 , 360 , 095  on Nov.  1 ,  1994 .   
    
    
     BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention relates generally to parking meters. More particularly, the present invention relates to individual parking meters that control multiple parking spaces or bays. 
     II. Description of the Prior Art 
     A variety of electronic and mechanical parking meters are. well-known in the prior art. Typical parking meters receive one or more coins to begin a timing interval during which a vehicle may remain parked in an appropriate space associated with and adjacent to the parking meter. 
     The timing interval, or the amount of time vended by the meter to the user, is typically determined by the number and value of the coins which are inserted into the parking meter. 
     Recently, electronic parking meters have evolved for digitally, electronically vending time. Although such electronic parking meters often have mechanical parts, the primary thrust of modern parking meter technology is directed to solid state circuitry and apparatus for parking meters which minimizes downtime, reduces mechanical unreliability, and provides an electronic means of accounting. 
     An advantage of modern electronic computerized parking meters is that they may be triggered externally without the use of coins. Accordingly, payment slots may be included for the use of debit cards which are incremented by the circuitry. Prepaid parking “time” represented by magnetic information on the cards may be used to vend time. 
     As an example, attention is directed to U.S. Pat. No. 4,880,097, owned by the same assignee as in this case. When such a “debit” card (i.e. normally the size of a plastic credit card) is used to purchase time, it need be simply inserted into the parking slot or the coin slot. Alternatively, the parking card and coins may be inserted into separate slots. A purchaser may vary the amount of time purchased on the meter, either by using his debit card or by inserting required coins. 
     A further advantage of the electronic meters is that fewer coins need be collected and handled, since much of the meter time is purchased by the park card. The meter then electronically stores in its memory the meter activity thereby reducing the number of coins in the meter. 
     Advanced electronic meters of the type described in the &#39;097 patent further simplify accounting procedures. An auditor is typically used to program the parking meter and/or to extract data from the parking meter, such as the activity of the meter, etc. Also, the auditor can be used to program and gather data from the parking meter by connecting the auditor directly. 
     Older mechanical parking meters require the meter reader to manually empty the coins from each meter and tally them to determine meter activity. With electronic parking meters, this may be substantially avoided. For example, accumulated parking time and accumulated sales may be stored within electronic memory. Moreover, “busy” times of the day may be computed. Electronic programming responsible for such meters allows the user to easily vary parking rates or change them when desired. 
     Outdoor vending devices such as meters must be capable of withstanding the elements. To lessen the likelihood of failures, the meters must be relatively well-protected from weather conditions. 
     However, known prior electronic and mechanical parking meters fail to maximize the potential storage capacity and vending capabilities of electronic meters while remaining user friendly. A desirous parking meter would be able to store multiple parking space activity while concurrently vending the multiple parking spaces. 
     Preferably, the meter would remain relatively simple to operate and would not require an operator to learn or acquire any new skills or programming expertise. Such a new parking meter would greatly increase the efficiency of the individual parking meter while reducing maintenance requirements, costs, accounting and verification procedures. 
     Ideally, this meter could record and store the activities for up to four parking spaces, thus requiring data to be retrieved from only one meter instead of several individual meters. Also, coins would only need to be collected from one meter. 
     Of course, a single multiple bay parking meter would consume less power than several single bay parking meters. Another requirement of any multiple bay parking meter would be that any operator would be able to accurately select the particular parking bay to be paid for. Such a multiple bay meter would preferably use a digital screen that would permit the operator to quickly identify the desired bay. Of course, the meter should require no special skills on the part of the operator to manipulate the meter. 
     SUMMARY OF THE INVENTION 
     My multiple bay parking meter permits a single meter to vend time to several parking bays concurrently. Three embodiments are illustrated. The two bay version may comprise either a digital display alone, or the display may be combined with a colored indicator using a rotary display flag-wheel. A four bay version omits the flag wheel. 
     The meter comprises a generally cubicle  cubical, exterior metallic casing that protectively houses the internal mechanism. The exterior casing also supports a removeable top. The top has a base and an integral arched portion that circumscribes a front view port and a back view port. 
     The casing interior houses the meter mechanism, that comprises a support frame, a front and a rear shell. A main circuit board is housed between the front shell and the rear shell. The generally cubicle frame portion includes a raised face portion that registers within a rectangular notch defined in the front of the casing. The face portion thus forms a portion of the meter exterior. 
     Portions of the payment system project outwardly from the exterior frame face. The payment buttons associated with the selection system also project outwardly from the frame face, and register with casing orifices that are adjacent to the notch. 
     The payment system and selection system permit an operator to selectively vend time for a chosen parking space or bay. Typically, payment system comprises a debit card slot and/or a coin slot for acceptance of payment. The debit card slot may receive a “debit” card that is mechanically guided and electronically interrogated through a variety of known techniques. 
     An internal card reader communicates with the card slot to accept and interrogate the card. A plug on the back of the reader extends through the front shell to connect to the main circuit board. 
     Coins inputted through the coin slot in the face drop into a chute system that may ultimately trigger the meter circuitry to initiate a vend. A plug on the back of the chute system extends through an orifice in the front shell to an appropriate connector on the main circuit board. 
     The selection system permits an operator to selectively choose which of the parking spaces or bays vended by the meter the operator desires to utilize. The selection system comprises an external switch plate, a plurality of external switches and an internal switch board. The switch plate rigidly mounts on the frame. 
     The switch board comprises a front connector that mounts directly to switch plate inside the frame. A plug projects on the opposite side of board. The plug extends through the front shell to the main circuit board. 
     A digital display is provided by an LCD display on the main circuit board. The meter displays the status of each bay via the LCD display. In the two bay embodiment, the meter uses digital indicators that may be combined with colored displays. All are visible through the top view ports. With the alternative two bay embodiment and the preferred four bay embodiment, only digital indicators are used. On all three embodiments, the front digital indicator may display the time remaining for a selected bay or the status of each bay. 
     On the preferred two bay embodiment, a colored flag wheel indicates the immediate status of each bay. Pie-shaped segments of the flag wheel are visible at the meter front through two side windows located adjacent each end of the digital indicator. The side windows reveal an immediate indication of the status of each bay indicated by the position of the colored segments. The back of the meter on the preferred two bay embodiment shows a selected portion of the multi-colored flag wheel in adjacent portions of a viewing window. The back of the flag wheel is also divided into several radially spaced apart, colored segments. Some segments are colored green to indicate that time is available; other segments are colored red to indicate that time has expired. Yellow segments critically located between other color segments identify when a jam has occurred. The flag wheel rotates to present an appropriate combination of segments through the meter windows for viewing from the meter exterior. In this manner service and enforcement duties are greatly simplified. 
     The alternative two bay embodiment and the four bay embodiment both omit the rotary flag wheel. Instead, these meters comprises a rear LCD display that functions in cooperation with the front LCD display. The four bay meter accommodates four separate parking spaces. 
     The preferred circuitry of all embodiments is substantially the same. The circuit uses a CPU that is interfaced with the multi bay plug. The CPU controls a stepper motor that rotates the flag wheel. The LCD display is also controlled by the CPU. 
     The circuit accommodates the switch inputs from the external buttons discussed earlier. When a button is pushed, a switch is selected by the multi bay card. The multi bay card applies voltage across an appropriate load resistor. This voltage is transmitted to a controller chip. 
     During vending, an operator selects the desired parking bay represented by appropriate external buttons, deposits funds and time is vended accordingly. Alternatively, the operator may deposit coins or insert a card prior to choosing a bay. If funds are predeposited, the meter escrows the deposited funds until a bay is chosen. 
     On power-up of a two bay meter, both spaces or bays will be expired with the LCD display showing “EE” and the flag wheel, if included, will display Red—Red to indicate “Expired” on the back while showing Red in the side display windows. On power-up of the alternative two bay meter, all bays or parking spaces will be expired, with the LCD showing “EE” on the front and rear numeric LCD&#39;s. On power-up on a four bay device, all bays or spaces will be expired with the LCD showing “EEEE” on the front and rear numeric LCD&#39;s. At this time the meter is in the idle loop waiting for a coin, card, or switch to be pressed. 
     If no switch is pressed and money is inserted, then the meter will alternately display “SEL” and “SPC” until the user selects a bay or space. This time will continue to “escrow” until a space is selected. If the user never selects a space and leaves, then the time escrowed will zero out after a specified timeout period programmed in the software. When a switch is pressed, the program will proceed to the multi bay switch handler. 
     If no switch is pressed and a card is inserted, then the meter will alternate displaying “SEL” and “SPC” until a space is selected. No deductions from a parking card will be taken until a switch is pressed thereby selecting a bay or space. 
     If a switch is pressed, the meter processes the information in a multi bay switch handler. The bay or space is determined from the CPU and the appropriate bay is set active. If there is time escrowed, the meter will credit the time to an appropriate bay or space. The LCD display is updated to the correct amount of time purchased and the optional two-bay flag wheel is moved to the correct position. The meter sets the space as active for a specified time interval after the last coin is inserted showing the time purchased in that bay. After a short time interval, the meter returns to the idle loop. The updated idle loop display for vended time is an “—” for each vended bay. 
     Thus a primary object of the present invention is to provide a low power parking meter for use in multi bay installation. 
     Another object is to provide a multi bay parking meter of the character described which avoids the use of external power, and minimizes the consumption of internal battery or capacitor stored charge. 
     A fundamental object is to monitor and control several parking spaces at once with a single meter. 
     Another important object is to provide a reliable, easy-to-use parking multi bay meter that is user friendly. 
     A related object is to provide a low power, multi bay parking meter of the character described that does not absolutely require user instructions to be inputted in a single sequence. It is an important feature of the meters described herein that the customer may first make a bay selection and then provide payment, or he may make payment first and then make a bay selection. 
     Another object of the invention is to provide a unique display technique wherein a plurality of parking spaces or bays can be monitored from a single meter. 
     A basic object is to provide a multi-bay parking meter for vending time for a plurality of parking spaces that accepts payment in the form of coins or cards. 
     A related object is to provide a display of the status of multiple parking bays without touching the parking meter. 
     Another object is to provide an electronic multi bay parking meter of the character described which avoids computer menu scrolling. It is a feature of our multiple bay meter designs that separate switches are provided for each bay that may be selected to minimize scrolling and enhance a user&#39;s chances to intuitively operate the meter. 
     A similar object is to provide a multi-bay parking meter with a computer control program that enables operators to quickly and easily discern how to operate the device. 
     Another object is to escrow money that is put in properly, so that once a financial input is made, the purchaser has a chance to select the proper bay to which the money should be applied. 
     Another important object of the invention is to provide a low power multi bay parking meter of the character described that allows the selection of space without programming skills. 
     These and other objects and advantages of the present invention, along with features of novelty appurtenant thereto, will appear or become apparent in the course of the following descriptive sections. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following drawings, which form a part of the specification and which are to be construed in conjunction therewith, and in which like reference numerals have been employed throughout wherever possible to indicate like parts in the various views: 
     FIG. 1 is a front isometric view of a two bay embodiment of our multiple bay parking meter that includes a rotary flag wheel; 
     FIG. 2 is a rear isometric view of the parking meter of FIG. 1; 
     FIG. 3 is a front isometric view of an alternative embodiment of a two bay parking meter that omits the flag wheel; 
     FIG. 4 is a rear isometric view of the parking meter of FIG. 3; 
     FIG. 5 is a front isometric view of a four bay parking meter; 
     FIG. 6 is a rear isometric view of the parking meter of FIG. 5; 
     FIG. 7 is an exploded isometric view of the meter shown in FIGS. 1 and 2, with portions omitted for clarity; 
     FIG. 8 is an exploded isometric view of the meter shown in FIGS. 3 and 4, with portions omitted for clarity; 
     FIG. 9 is an exploded isometric view of the four-bay meter shown in FIGS. 5 and 6, with portions omitted for clarity; 
     FIG. 10 is a front elevational view showing the two bay parking meter of FIGS. 1,  2  and  7  with the front display showing time available in bay “A” and time expired in bay “B;” 
     FIG. 11 is a rear elevational views of the meter shown in FIG. 10; 
     FIG. 12 is a greatly enlarged, front elevational view of the display shown in FIG. 10, showing the front digital indicator and the side color indicators that display the status of both bays; 
     FIG. 13 is a greatly enlarged, rear elevational view of the display shown in FIG. 11, showing the rear color indicators that display the status of both bays concurrently with the front display of FIG. 12; 
     FIG. 14 is a greatly enlarged, front elevational view of the display similar to FIG. 12, showing the front digital indicator and the side color indicators that display the status of both bays, immediately after a bay-select switch has been depressed; 
     FIG. 15 is a greatly enlarged, rear elevational view of the display similar to FIG. 13, showing the rear color indicators that display the status of both bays concurrently with the front display of FIG. 14; 
     FIG. 16 is a greatly enlarged, front elevational view of the display similar to FIG. 12 indicating the time remaining for selected bay “A”; 
     FIG. 17 is a greatly enlarged, rear elevational view of the display showing the rear color indicators that display the status of both bays concurrently with the front display of FIG. 16; 
     FIG. 18 is a greatly enlarged, front elevational view of the display similar to FIG. 12, showing the front digital indicator and the side color indicators that display the status of both bays, indicating that the vended time has expired for both bays “A” and “B;” 
     FIG. 19 is a greatly enlarged, rear elevational view showing the rear color indicators that display the status of both bays concurrently with the front display of FIG.  18  and indicating that the vended time has expired for both bays; 
     FIG. 20 is an elevational view of the front of the rotary flag wheel indicator with the display segments lined for color; 
     FIG. 21 is an elevational view of the rear of the flag wheel indicator with the display segments lined for color; 
     FIG. 22 is an electronic schematic diagram of the preferred main circuit board assembly circuitry; 
     FIG. 23 is an electronic schematic diagram of the preferred bay switch board circuitry; 
     FIG. 24 is a flow diagram of the software routine for the parking meter; and, 
     FIG. 25 is a flow diagram of the software routine for the switch handler. 
    
    
     DETAILED DESCRIPTION 
     The apparatus to be hereinafter described in most advantageously employed in conjunction with parking meters. However, the teachings of the present invention relate to vending machines in general, and particularly to those vending machines which include electronic circuitry for monitoring vends, sales, time increments, accumulated sales, and the like. 
     The present invention is ideally adapted for modern electronic parking meters, such as the meter of U.S. Pat. No. 4,823,928 owned by the same assignee as in this case. For disclosure purposes the latter reference is incorporated by reference herein. 
     In the various Figures three embodiments are illustrated. The two bay version may comprise either a digital display alone, or the display may be combined with a colored indicator using a rotary display flag-wheel to be hereinafter described. A four bay version omits the flag wheel. Most of the interior components, such as those seen in FIGS. 1-2, are common to all embodiments. 
     Two Bay Meter with Combined Color and Digital Display 
     An initial embodiment of our improved multiple bay parking meter has been generally designated by the reference numeral  40 . Meter  40  is especially adapted for two bay operation (i.e., it handles two parking spaces). Preferably meter  40  comprises a generally cubicle, exterior metallic casing  45  (FIGS. 1,  2  and  7 ) that protectively houses the internal mechanism  57  to be discussed hereinafter. Casing  45  supports a removable top  50  having a base portion  51 . The removable rate plate  55  fits over base  51 . An integral arched portion  53  circumscribes a front view port  52  and a back view port  54 . Preferably, both ports use see-through, shatterproof glass so that an operator can view the displays housed therein. As is well recognized in the art, the casing is normally fastened to a suitable stanchion in use, disposed adjacent the parking space or spaces to be rented. 
     The casing interior houses the meter mechanism  57 , that comprises a support frame portion  62 , a front shell  64  and a rear shell  66 . A main circuit board  65  is housed between the front shell  64  and the rear shell  66 . Front shell  64  includes a number of clearance orifices as illustrated. The CPU PROM socket  61  on the circuit board  65  may be accessed through access orifice  67  in front shell  64 . A removable PROM access plug  73  is normally fitted to orifice  67 . 
     The generally cubicle support frame portion  62  includes a raised face portion  63  (FIG. 7) that registers within a rectangular notch  47  defined in the front of casing  45 . The face portion thus forms a portion of the meter exterior. Portions of the payment system  70  project outwardly from face  63 . The payment buttons associated with selection system  80  project outwardly from face  63 , and register with orifices  81 A,  82 A in casing  45  adjacent notch  47 . 
     Payment system  70  and selection system  80  penetrate frame  62  to permit an operator to selectively vend time for a chosen parking space or bay. Typically, payment system  70  comprises a debit card slot  72  and/or a coin slot  74  for acceptance of payment. Slot  72  may receive a “debit” card that is mechanically guided and electronically interrogated through a variety of known techniques. An internal card reader  76  communicates with slot  72  to accept and interrogate the card. A plug  69  on the back of card reader  76  extends through an orifice  69 B in front shell  64  to connector  69 A on circuit board  65 . Typical card receptor mechanisms for receiving debit cards and communicating with their integrated circuit and logic is seen in one or more of the following U.S. patents, issued to Alcatel CIT, Paris, France: U.S. Pat. Nos. 4,900,272, 4,900,273, 5,012,078, and 5,051,566. 
     Electronic parking meters that accept payment cards to vend parking time are thus well-known in the art. Specifically, prior U.S. Pat. Nos. 4,823,928 and 5,360,095, owned by the same assignee as in this case relate to parking meters that accept payment cards. For disclosure purposes, the latter references are hereby incorporated by reference herein. 
     Coin acceptance is discussed in detail in U.S. Pat. Nos. 4,823,928 and 4,895,238 owned by the same assignee as in this case, and which are incorporated by reference herein. Payment coins inputted through coin slot  74  in face  63  drop into a chute system  78  that may ultimately trigger the meter circuitry to initiate a vend. Chute system  78  is assembled proximate the interior of support frame  62 . Coin input region  75  is positioned adjacent slot coin input slot  74  in assembly. The top of region  75  is positioned beneath coin-drop access slot  77  in frame  62 . A coin chute access plate  83  removably covers slot  77 . An electrical plug  71  on the back of coin chute system  78  extends through clearance orifice  79  in front shell  63  to connection plug  79 A projecting from circuit board  65 . Digital readings are provided by LCD display  91  on board  65 . 
     Selection system  80  permits an operator to selectively choose which of the parking spaces or bays vended by the meter the operator desires to utilize. The selection system  80  comprises an external switch plate  82 , a plurality of external switches and an internal switch board  90 . The switch plate  82  rigidly mounts on frame  62  (FIGS.  1 - 6 ), and it has either two or four clearance orifices (i.e., orifices  81 A and  82 A) to accommodate the push-button bay select switches (i.e.,  84 A and  84 B) to be hereinafter described. Switch board  90  comprises a front connector  92  that mounts directly to switch plate  82  inside frame  62 . A plug  94  projects on the opposite side of board  90 . Plug  94  extends through orifice  93  in front shell  63  to board  65  via plug  95 . 
     Meter  40  displays the status of each bay using either colored indicators or digital indicators that are visible through top  50 . With the preferred two bay embodiment, colored indicators and digital indicators are both used (see FIGS.  10 - 19 ). With the alternative two bay embodiment and the preferred four bay embodiment, only digital indicators are used. On all three embodiments, the front digital indicator  100  may display the time remaining for a selected bay or the status of each bay. 
     On the preferred two bay embodiment, a colored rotary wheel  101  indicates the immediate status of each bay. A selected pie-shaped portion of wheel  101  is visible through two side windows  102 ,  104 , located adjacent each end of digital indicator  100 , provide an immediate indication of the status of each bay. The back of meter  40  on the preferred two bay embodiment uses a rear window  105 . On the preferred two bay embodiment, the rear window  105  has right and left sides  106 ,  108  (FIG. 2) to show a selected portion of multi-colored flag wheel  101 . 
     As best seen in FIG. 20, the front of the flag wheel is preferably divided into eight radially spaced apart, pie-shaped segments,  110 - 117 . Pie-shaped segments  110 ,  112  and  114  are colored green to indicate that paid-for time is unexpired for a particular parking bay. Segments  111 ,  113  and  115  are colored red to indicate that time is expired. Segments  116  and  117  are colored yellow to indicate that the meter is jammed or otherwise requires service. The flag wheel  101  is rotated to present an appropriate combination of segments  110 - 117  through front windows  102  or  104  for viewing from the meter exterior. 
     The rear of the flag wheel is divided into radially spaced apart, pie shaped segments  119 ,  121 ,  123  and  125  that are concurrently displayed through the rear window  105 . Segments  119  and  121  on the rear face of the flag wheel  101  are colored red to indicate time expiration. Segment  125  is green. Segment  123  is yellow, and represents that the meter needs service. The colored sold-out display on the front of the meter is seen in FIGS. 12,  14 ,  16  and  18 . The smaller colored wheel segments  113 ,  114  are necessary since the windows  102  and  104  in the meter front are spaced apart. The rear viewing windows are adjacent one another (FIG. 11) so less colored segments on the flag wheel rear face are necessary. 
     The latter colored segments are presented to the viewing windows by appropriate rotation of the flag wheel  101  to the position seen in FIG.  19 . FIGS. 13,  15  and  17  indicate other rear display possibilities. FIG. 18 indicates the display achieved when time has expired with both parking spaces; colored flag wheel segments are behind windows  102  and  104 . When time has been purchased for space A, as in FIGS. 16-17, but not for space B, the wheel rotates to show green in window  102 , while window  104  may still be red. When time for space B is vended, wheel  110  rotates to color window  104  red. When time is purchased for both slots, then red segments are placed behind windows  102  and  104 . The rear window sides  106  and  108  are colored concurrently by matching color segments that rotate with wheel  110  at the meter rear. The yellow segments of the wheel  101  are displayed when the computer senses a jammed condition, or the unit otherwise requires service. 
     Two Bay Meter with Digital Display 
     Meter  40 B (FIGS. 3,  4 , and  8 ) is largely the same as meter  40  discussed above. However, it omits the flag wheel  101 , and the front and rear viewing windows discussed earlier. However, as seen in FIG. 4, meter  40 B comprises a rear digital display  109  that functions in cooperation with display  100  on the front. The color display window indicators  102 ,  104 ,  106  and  108  discussed previously are not used. A rear digital indicator  109  that is identical to the front digital indicator  100  is used instead. Modified rear shell  66 C (FIG. 8) includes a display viewing orifice  98  for mounting window glass  99 . 
     Four Bay Meter with Digital Display 
     Meter  40 C (FIGS. 5,  6 , and  9 ) is largely, insofar as digital display techniques, the same as two-bay meter  40 B discussed above. However, four-bay meter  40 C accommodates four separate parking spaces. Like meter  40 B, it omits the flag wheel  101  and the front and rear viewing windows  102 ,  104 , and  105  discussed earlier. However, four space selection buttons  84 A- 84 D are employed on payment system  60  (FIG.  9 ). These buttons register rearwardly through orifices  83 E in frame  62 B and engage with support plate  90 A. The push button faces project exteriorly outwardly of the meter through the orifices  82 E in the modified plate  82 C (FIG.  9 ). Modified rear shell  66 B includes a display viewing orifice  98  for mounting window glass  99 . Meter  40 C comprises a rear digital display  109  that functions in cooperation with display  100  on its front. 
     Preferred Circuitry 
     The preferred circuitry of all embodiments of the present invention comprises a modification of that seen in prior U.S. Pat. Nos. 4,823,928 and 5,360,095, owned by the same assignee as in this case. Both relate to parking meters that employ the low power solid state circuitry. For disclosure purposes, the latter references are incorporated by reference herein. 
     With reference to FIG. 22, circuit  400  is largely borrowed from the above referenced patents. CPU  402  is interfaced with the multi bay plug  79 A though lines  404 . The flag wheel  101  is driven by a stepper motor controlled by lines  403 . Lines  403  interconnect with the CPU  402  via lines  404 . The display driver  409  is driven through lines  410  leading to the CPU. The front LCD display, used with all models, is designated by the reference numeral  413 . The rear LCD display, that is used on all units that omit the flag wheel  101  has been designated with the reference numeral  414 . 
     Circuit  450  (FIG. 23) accommodates the switch inputs such as switches  84 A- 84 D discussed earlier. Lines  452  generally correspond to the plug connection  79 A referenced earlier that plugs into the multi-bay plug detail seen in the left portion of FIG.  22 . Switch  401  is provided to enable the circuit  400  to be quickly switched between conventional single bay units and the herein described multi-bay systems. The mechanical switches  84 A- 84 D correspond generally to the push button switches  460 - 463  shown schematically. When a switch  460 - 463  is selected, it applies voltage across its load resistor  466 - 469  respectively. This voltage is transmitted to eight-bit encoder chip  470  via one of the lines  472 . 
     Encoder chip  470  outputs via resistors  474 - 476  to driver transistors  478 - 480  respectively. The collector output of driver transistor  478  appearing on line  482  delivers an interrupt request to the CPU to warn that a meter selection is following. The interrupt signal indicates that, in a multi bay environment, one of a plurality of bays has received attention. For example, this may occur when a customer inserts coins or payment and activates the switches to select a bay. Once line  482  drops when transistor  478  is turned on, the logic state of lines  483  and  484  are queried to determine what parking bay is effected. If both lines  483  and  484  remain high, (i.e., logical 00) bay “A” has been selected. If line  483  drops in voltage (i.e., corresponding to a logical 01), then bay “B” is involved. Bay “C” receives attention if line  484  drops. If both lines  483  and  484  drop, corresponding to a logical 11, then bay “D” (i.e., the fourth parking space) is involved. In each instance the CPU will be directed to account for transactions and to associate them with a particular bay, and the displays and the financial accounting will be tied to a given parking space. 
     Preferred Software 
     The main routine  500  is seen in FIG.  24 . An idle loop  502  executes during periods of inactivity. At this time the apparatus is waiting for a coin, a debit card, or a bay switch input. Activity occurs when either a coin is inserted (step  504 ), a payment card is inserted (step  506 ), or a bay selection button is first pushed, indicated by step  508 . When a bay selection switch is pressed, switch handler routine  510  to be described later is executed. Afterwards a return to idle loop  502  occurs as indicated by line  509 . 
     If a coin was first inserted, as indicated by step  504 , the LCD display will alternately flash “Sel” and then “Spc” to prompt the customer to choose a space by pressing the appropriate selection button. Concurrently, the dollar amount of coinage inserted will be “remembered” or escrowed as in step  511  until a parking spot is selected through the switch handler routine  510  is indicated by lines  512  and  513 . If a switch is pressed, the switch handler routine  510  is executed, and afterwards a return to the idle loop  502  occurs as indicated by line  509 . 
     If a payment card was first inserted, as indicated by step  506 , the display will flash “Sel” and then “Spc” to prompt the customer to choose a space. Concurrently, the card transaction amount is escrowed in step  514 . Then as indicated by lines  516  and  513 , the routine waits for the switch handler step  510 . If a switch is activated, the switch handler routine  510  is executed, and afterwards a return to the idle loop  502  occurs. 
     The switch pressed step  508  occurs in response to customer activation of one of the push button switches  84 A- 84 D. The switch handler step  510  follows. 
     The switch handling routine  510  looks for the selection of a particular bay in step  550 . Decision step  552  waits for the input of money or a card for a preselected time, and if no value is inputted, it executes step  554  to return that space to inactive status, and returns to the idle loop with step  556 , so that the apparatus may again go idle. 
     If credit in escrow is found in step  552  within the time limits, the correct space is made active in step  558 . Time is vended to the appropriate space in step  560 , and the amount of time remaining is updated on the display in step  562 . Flag wheel instructions are generated in step  564 , and a return to idle mode is made in step  566 . 
     Operation 
     Normally, the meter functions in the “idle loop” mode to conserve power. During the “idle loop”, the digital front indicator on all embodiments shows either a “-” for each bay for which time remains and an “E” for each bay for which no time remains. Additionally, on the preferred two bay embodiment, the side indicators  102 ,  104  show green if time remains or red if time has expired. The rear window sides  106 ,  108  on the two bay embodiment correspondingly show green or red. 
     The preferred four bay embodiment uses front and rear indicators  100 ,  109 . Since the meter displays the status of each bay during the “idle loop”, a patrol person can easily identify which bays have time remaining and act appropriately. Upon selection switch depression, the meter displays the time remaining for the selected bay. After a predetermined display period, the meter automatically returns to an “idle loop” to conserve power. 
     During vending, an operator selects the desired parking bay represented by switches  84 A- 84 D, deposits funds and time is vended accordingly. Alternatively, the operator may deposit coins or insert a card prior to choosing a bay. If funds are predeposited, the meter escrows the deposited funds until a bay is chosen. 
     On power-up of a two bay meter, both spaces or bays will be expired with the LCD display showing “EE” (FIG. 18) and the flag wheel, if included, will display Red to indicate “Expired” on the back while showing Red—Red in the frontal display windows (FIGS. 18,  19 ). On power-up, all bays or parking spaces will be expired, with the LCD showing “EE” on the front and rear numeric LCD&#39;s (FIG.  18 ). On power-up on a four bay device, all bays or spaces will be expired with the LCD showing “EEEE” on the front and rear numeric LCD&#39;s. At this time the meter is in the idle loop (i.e., step  502  in FIG. 24) waiting for a coin, card, or switch to be pressed. 
     If no switch is pressed and money is inserted then the meter will alternately display “SEL” and “SPC” until the user selects a bay or space. This time will continue to “escrow” until a space is selected. If the user never selects a space and leaves, then the time escrowed will zero out after a specified time out period programmed in the software. When a switch is pressed then the meter will proceed to the switch handler. 
     If no switch is pressed and a card is inserted then the meter will alternate displaying “SEL” and “SPC” until a space is selected. No deductions from a parking card will be taken until a switch is pressed thereby selecting a bay or space. 
     If a switch is pressed, the meter processes the information in the multi bay switch handler. The bay or space is determined from the CPU and the appropriate bay is set active. If there is time escrowed, the meter will credit the time to an appropriate bay or space thereby updating the LCD display to the correct amount of time purchased and moving the optional two-bay flag wheel to the correct position indicated by the tables below. The meter sets the space as active for a specified time interval after the last coin is inserted showing the time purchased in that bay. After the time interval, the meter updates the display. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 TWO BAY FLAG WHEEL DISPLAY 
               
             
          
           
               
                 METER 
                   
                   
                   
               
               
                 CON- 
                 FLAG WHEEL 
                 FLAG WHEEL 
                 LCD 
               
               
                 DITION 
                 FRONT 
                 REAR 
                 DISPLAY 
               
               
                   
               
             
          
           
               
                 Expired 
                 Red-Red 
                 Red 
                 E 
                 E 
               
               
                 A timing, 
                 Green-Red 
                 Red-Green 
                 — 
                 E 
               
               
                 B expired 
               
               
                 A expired, 
                 Red-Green 
                 Green-Red 
                 E 
                 — 
               
               
                 B timing 
               
               
                 A timing, 
                 Green-Green 
                 Green-Green 
                 — 
                 — 
               
               
                 B timing 
               
             
          
           
               
                 A active 
                 Not updated 
                 Not updated 
                 Shows time 
               
               
                   
                   
                   
                 on Space A 
               
               
                 B active 
                 Not updated 
                 Not updated 
                 Shows time 
               
               
                   
                   
                   
                 on Space B 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
             
               
               
               
               
               
             
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 FOUR-BAY DIGITAL DISPLAY 
               
             
          
           
               
                 METER CONDITION 
                 LCD DISPLAY 
               
               
                   
               
             
          
           
               
                 Expired 
                 E 
                 E 
                 E 
                 E 
               
               
                 A timing, B expired, C expired, D expired 
                 — 
                 E 
                 E 
                 E 
               
               
                 A expired, B timing, C expired, D expired 
                 E 
                 — 
                 E 
                 E 
               
               
                 A timing, B timing, C expired, D expired 
                 — 
                 — 
                 E 
                 E 
               
               
                 A expired, B expired, C timing, D expired 
                 E 
                 E 
                 — 
                 E 
               
               
                 A timing, B expired, C timing, D expired 
                 — 
                 E 
                 — 
                 E 
               
               
                 A expired, B timing, C timing, D expired 
                 E 
                 — 
                 — 
                 E 
               
               
                 A timing, B timing, C timing, D expired 
                 — 
                 — 
                 — 
                 E 
               
               
                 A expired, B expired, C expired, D timing 
                 E 
                 E 
                 E 
                 — 
               
               
                 A timing, B timing, C expired, D timing 
                 — 
                 — 
                 E 
                 — 
               
               
                 A expired, B expired, C timing, D timing 
                 E 
                 E 
                 — 
                 — 
               
               
                 A timing, B expired, C timing, D timing 
                 — 
                 E 
                 — 
                 — 
               
               
                 A expired, B timing, C timing, D timing 
                 E 
                 — 
                 — 
                 — 
               
               
                 A timing, B timing, C timing, D timing 
                 — 
                 — 
                 — 
                 — 
               
             
          
           
               
                 A active 
                 Shows time 
               
               
                   
                 an Space A 
               
               
                 B active 
                 Shows time 
               
               
                   
                 on Space B 
               
               
                 C active 
                 Shows time 
               
               
                   
                 on Space C 
               
               
                 D active 
                 Shows time 
               
               
                   
                 on Space D 
               
               
                   
               
             
          
         
       
     
     From the foregoing, it will be seen that this invention is one well adapted to obtain all the ends and objects herein set forth, together with other advantages which are inherent to the structure. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.