U. S. Patent 4,717,815, the disclosure of which is hereby incorporated by reference herein, discloses a time metering device particularly useful as a parking card. The parking card is used to prepurchase time for parking in parking spaces for which a municipality having jurisdiction over the parking spaces has established a parking charge rate. The motorist purchases the parking card from the municipality at a cost at least as great as the value of the prepurchased time.

The parking card comprises a time storage device for, storing data representing total prepurchased time, a time measuring device, time selector keys for manually selecting a predetermined time interval, a predetermined interval storage device, and an off key. The time metering device further includes an electrical circuit which decrements both the prepurchased time storage device and the predetermined interval storage device according to the time measured by the time measuring device until the off key is operated, and a display which displays the remaining time in the prepurchased and predetermined interval storage devices. The motorist selects the time for which parking is desired and then places the card in a location where it can be seen by a meter maid.

So long as the time metering device has not timed out, the display will indicate that the motorist has paid for parking.

When the motorist wishes to terminate paying for parking, she presses the off key and the decrementing stops.

A disadvantage of the parking card disclosed in U. S.

Patent 4,717,815 is that it cannot be recharged and therefore when the prepurchased time has been decremented to zero, the parking card can no longer be used.

Disadvantages also exist for existing parking cards that are rechargeable. All rechargeable parking cards require the

user to turn in his/her parking card when recharging is necessary. This burdens the user by requiring him/her to deliver or mail the parking card to the municipality, and either doing without a card for a while or be issued an additional card by the municipality. Furthermore, the card turned in by a user, can only be returned to that user unless the municipality also reconditioned every recharged parking card. If parking cards turned in for recharge were not reconditioned, a meticulous user could turn in a parking card of good appearance and be given in return, after recharging, someone else's parking card of poor appearance.

A known type of postage meter has a bank which is precharged with a selected amount of currency and the bank is decremented by a selected amount each time the meter is used.

When the bank is nearly broke, the user can recharge the bank by remitting payment to a central service bureau and enabling a recharge mode after the service bureau has received the payment. In the recharge mode, the meter displays a recharge code. The user calls the central service bureau and informs the bureau of the recharge code. The bureau calculates a validation code from the recharge code using a secure algorithm and supplies the validation code to the user. The user enters the validation code using the postage meter's keypad. The circuitry within the postage meter compares the validation code with the recharge code using the same secure algorithm, which is stored in the postage meter, and if the two codes are in the correct relationship, the meter is recharged. This validation procedure has the advantage that it allows virtually unlimited recharging operations without its being necessary for the service bureau to keep track of information relating to each postage meter in service.

Given access to sufficient postage meters, it would be possible to derive the algorithm that is used to calculate the validation code. However, a member of the general public would probably experience significant difficulty in obtaining access to more than one or two postage meters, and therefore there is in fact little danger that someone would be able to derive the secure algorithm.

An algorithmic validation mechanism is not suitable for use with a rechargeable parking card, because, it would be much easier to obtain access to sufficient cards to derive the algorithm, thereby enabling the card to be recharged without making payment.

Devices that use an algorithmic validation mechanism are also open to a systemic failure. Once the algorithm is discerned for one device, then all devices are susceptible. A large black market operation of unknowable size, could arise, illegally recharging the parking cards.

Algorithmic validation is also not suitable for use with rechargeable parking cards, since these cards need to be low cost and are powered by a small lithium battery for many years. To meet the requirement for low cost and power consumption, parking cards are designed using simple 4 bit microprocessors. These 4 bit microprocessors are inexpensive and have extremely low power consumption. An artifact of these traits though, is limited computational power.

Typically, these 4 bit microprocessors have an extremely limited instruction set, a very low instruction execution rate (typically 100 times slower than a normal microprocessor), and very limited ROM resources. These characteristics prevent the 4 bit microprocessors from implementing sophisticated and secure recharge algorithms.

Parking cards are designed to be maintenance free and therefore typically have a permanently installed battery.

This permanently installed battery limits the life span of the parking card to three to four years. Because of this limited life, there is no benefit to unlimited recharging capability.

Summarv of the Invention In accordance with a first aspect of the invention there is provided a time metering device particularly useful as an in-car parking meter, comprising a storage device for storing a variable representing pre-purchased time and at least one randomly selected recharge code, a time measuring device, an interface for entering a command to decrement pre-purchased

time in accordance with passage of time measured by the time measuring device and for entering a code, and a display device for displaying status information, whereby when the user enters a code which matches a valid recharge code stored in the storage device, the value of the variable representing pre-purchased time is altered to indicate a predetermined increase in pre-purchased time.

In accordance with a second aspect of the invention there is provided a method of administering a parking facility, comprising obtaining a plurality of time metering devices each including a storage device for storing at least one variable representing pre-purchased time and at least one recharge code, a time measuring device, an interface for entering a command to decrement pre-purchased time in accordance with passage of time measured by the time measuring device and for entering a code, wherein the recharge codes stored in the storage devices of the plurality of time metering devices respectively are selected at random, issuing at least one time metering device to each user of the parking facility and providing each user with a user- intelligible record of at least one recharge code stored in the storage device of the time metering device issued to that user, whereby the user can reset the value of the variable representing pre-purchased time by entering the recharge code.

In accordance with a third aspect of the invention there is provided an in-car parking meter comprising electronic circuitry for performing a time metering function, a rechargeable electric storage cell connected to the electronic circuitry to supply operating current thereto, and a photoelectric cell connected to the storage cell for charging the storage cell when the photoelectric cell is exposed to daylight.

In accordance with a fourth aspect of the invention there is provided an in-car parking meter comprising electronic circuitry for performing a time metering function and periodically generating an authentication code, and a display for displaying the authentication code.

In accordance with a fifth aspect of the invention there is provided an in-car parking meter comprising a storage device for storing a variable representing pre-purchased time and a first transition time, a real time clock for detecting passage of time, a decrementing means for decrementing the variable representing prepurchased time in accordance with passage of time detected by the real time clock, the decrementing means having an inactive condition in which the decrementing means is off and does not decrement the variable and an active condition in which it is on and decrements the variable, and a stand-by condition in which it is on and does not decrement the variable, an interface for activating the decrementing means, and a control means responsive to the real time clock to place the decrementing means in the stand- by condition if the decrementing means is activated before the first transition time and to change the decrementing means to the active condition at first the transition time.

In accordance with a sixth aspect of the invention there is provided an in-car parking meter comprising a storage device for storing a variable representing pre-purchased time and a first transition time, a real time clock for detecting passage of time, a decrementing means for decrementing the variable representing prepurchased time in accordance with passage of time detected by the real time clock, the decrementing means having an inactive condition in which the decrementing means is off and does not decrement the variable and an active condition in which it is on and decrements the variable, and a stand-by condition in which it is on and does not decrement the variable, an interface for activating the decrementing means, and a control means responsive to the real time clock to place the decrementing means in the active condition if the decrementing means is activated before the first transition time and to change the decrementing means to the stand-by condition at first the transition time.

Brief Description of the Drawings For a better understanding of the invention, and to show how the same may be carried into effect, reference will now

be made, by way of example, to the accompanying drawings, in which I FIG. 1 is a block diagram illustrating the functional components of a parking card in accordance with the present invention, FIG. 2 illustrates the front face of the parking card shown in FIG. 1, FIGS. 3 and 4 are flow charts illustrating one mode of operation of the parking card for single city and dual cities respectively, FIGS. 5 and 6 are flow charts illustrating another mode of operation, for single city and dual cities respectively, FIGS. 7-51 show typical displays presented by the parking card, FIG. 52 is a flow chart illustrating an auto start/stop mode of operation, and FIG. 53 is a flow chart illustrating generation of an authentication codeword.

Detailed Description The terms"city"and"municipality"are used herein to designate the government agent having jurisdiction over parking spaces and authority to establish a parking charge rate. The terms are used interchangeably, without regard to whether a particular jurisdiction is recognized under applicable law as a city. The term"parking facility"is used herein to designate a region in which parking can be controlled and includes both a system of on-street parking spaces in a city and a private facility, such as an open air parking lot or a multi-story parking structure. In the case of the parking facility being the system of on-street parking spaces in a city, administration of the parking system may be carried out by or under the authority of a government agency, whereas in the case of a private parking facility, administration may be carried out by or under the authority of the owner of the parking facility.

The parking card illustrated in FIGS. 1 and 2 includes a microprocessor 10, a random access memory (RAM) 14, a read

only memory (ROM) 18 which stores the program for operating the microprocessor, a user interface 22 and a real time clock 24. The user interface 22 includes a display panel 26 and several keys 28, which operate respective switches. The display panel has several regions. It will be seen that a parking card in accordance with the present invention has a similar topology to the parking card shown in U. S. Patent 4,717,815. However, it has significantly greater functionality.

FIG. 2 shows the key layout and display elements of a preferred parking card in accordance with the present invention.

The keys are an on key, a select up key, a select down key, a shift key, an OK key and an off key.

The regions of the display panel include a zone display region 30, a zone legend region 32, a four-digit display region 34, a bar graph region 35, a parking symbol region 36, a time display region 37, a confirmation region 38, a void legend region 39 and a lock region 42. The functions of the different regions of the display are described below.

The zone display region 30 contains a single character used for displaying a single letter representing a parking zone, or in a city mode, to indicate the choice of cities.

The zone legend 32 is on when the display region 30 is used for indicating a zone and is off when the display region 30 is used for indicating a city.

The four digit display region 34 contains four characters each displaying a numerical digit in the range 0-9 or a letter from A through F. The four digit display is used for selecting and entering a personal code or for displaying a time.

The parking symbol P in the region 36 is on when the parking card has been set to pay for parking, and the four digit display then shows unexpired parking time in that zone.

The confirmation symbol OK in the region 38 when on indicates that a valid entry has been made and that the OK button should be pressed in order to start paying for parking.

The time symbol T in the region 37 shows the total parking time remaining if the confirmation symbol is also on, but otherwise indicates that the four character display shows the actual time, as measured using the real time clock.

The void alert in the region 40 provides a warning that no funds are available to pay for parking.

The lock region 42 shows whether a personal code must be entered in order to pay for parking.

The manner of operation of the microprocessor in accordance with the program stored in the ROM and in response to operation of the various keys will become apparent from the following description of the various functions performed by the parking card.

It will be assumed for the purpose of the following description that the initial condition of the parking card is off so that the display is blank. In this condition, the parking card will only respond to the on/mode key.

When a user purchases the parking card from an agency responsible for administering sale and recharging of parking cards for one or more municipalities, she purchases parking in either one city or in two cities, referred to herein as City A and City B. The RAM is loaded with a number representing the purchase price of the parking. The corresponding time purchased depends on the zone in which parking is to be purchased. The RAM therefore also stores data representing the parking rate for each parking zone in each city and any limitations regarding, for example, the maximum time that can be purchased in a given zone. The issuing agency can configure the parking card so that it cannot be used to pay for parking unless the user has entered a valid personal code. Even if the issuing agency does not require entry of a valid personal code, the user can configure the parking card so that it cannot be used to pay for parking unless a valid personal code has been entered.

The random access memory (RAM) is able to store data relating to two municipalities and a bank is associated with each municipality. Accordingly, a purchaser who frequently parks in two different cities which issue parking cards, can

charge one bank to pay for parking in one city and can charge the other bank to pay for parking in the other city.

The RAM stores several random numbers representing unique recharge codes which will be used in order for successive recharge operations. When the parking card enters the recharge mode, the next available recharge code is selected. The parking card will typically be charged at initial purchase, allowing immediate use. When the first parking credits have been depleted, the user purchases the first recharge code for his/her particular parking card. The user receives the other codes incrementally, receiving the next available recharge code with each purchase of additional parking.

The use of a stored random number to validate recharging has the advantage over a conventional postage meter system, employing a stored algorithm, that it is not possible to derive the code by testing numerous parking cards.

The manner of operation of the preferred parking card in accordance with the invention will now be described in detail.

All mode displays stay on for 30 seconds from last key stroke, unless terminated by OK or OFF. If the parking card is off (blank display), it will only respond to the ON key.

PERSONAL CODE REQUIRED OR SET If the parking card is off and ON/MODE is pushed, what happens next depends upon whether or not the personal code has been set by the user and/or is required by the municipality. If required and not set, before the parking card will allow any other mode, the personal code must be set. In this case, the display of FIG. 7 is shown, independent of the number of times the ON key was pressed, with the selected digit flashing (initially the first digit).

Modify the selected digit's value by using SELECT UP and SELECT DOWN keys. Acceptable digits are 0 through 9 as well as the letters A, b, C, d, E, F. SELECT UP, at each keypress, causes the flashing digit to increment in the order 3,4,5,6,7,8,9, A, b, C, d, E, F, SELECT

DOWN, at each keypress, causes the flashing digit to decrement in the order (F, E, d, C, b, A, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, F, E, d ...).

After setting selected digit (the flashing digit) to the value desired, select the next digit to be modified by using the SELECT DIGIT key. The SELECT DIGIT key, each time it is pressed, moves the selected digit (the flashing digit) right one digit. If at the rightmost digit on the LCD display, pressing the SELECT DIGIT key, selects the leftmost digit of the four digit set.

In this manner, the digits can be adjusted to display a desired group of four characters.

After entering in a personal code, the OK key is used to store it. The OK key will enter the personal code only when all four digits have been modified and then only if the OK key is held down 2 seconds. For example, if the user had entered his/her code and pressed the OK key for 2 seconds, then the display of FIG. 8 is shown for successful personal code entry. Note, the OK symbol in the display is flashing, indicating that the user may press the OK key to continue.

The display will remain for 30 seconds or until the ON key, the OFF key, or the OK key is pressed.

Pressing the ON key, before personal code entry completion, restarts the entry back at the initial display of the personal code entry. Pressing the OFF key before personal code completion, aborts the process and blanks the display.

If the personal code is set, before the parking card will allow any other mode, the user's personal code must be correctly entered. The display in FIG. 9 is shown, independent of the number of times the ON key was pressed, with the selected digit flashing (initially the first digit).

The user enters his personal code by adjusting the display to the desired value as described above.

After the user enters his personal code, the OK key is used to validate it. Pressing the OK key will cause the personal code entered to be validated against the stored value. The display in FIG. 10 will be shown upon valid

personal code entry. The display will remain for 30 seconds or until the ON key, OK key or the OFF key is pressed.

The display in FIG. 11 will be shown upon invalid personal code entry. The display will remain for 30 seconds or until the ON key, OK key or the OFF key is pressed.

Pressing the ON key, before personal code entry completion or upon validation failure, restarts the entry back at the initial personal code validation display.

Pressing the OFF key before personal code completion, aborts the process and blanks the display.

If the user fails five consecutive personal code validations, a 10 minute timer is invoked that prevents normal operation. During this 10 minute interval, the display in FIG. 12 is shown with the T symbol flashing. No key will be responded to during this 10 minute interval.

If a personal code is not required or set, the modes described above are not entered.

After the correct entry of the personal code, the parking card remains unlocked for 15 minutes or until 1 minute after Parking is OK'd. When unlocked, the parking card allows all normal modes. These modes and their sequencing are described in sections, OPERATIONAL MODES SEQUENCING and ADJUSTMENT MODES SEQUENCING.

OPERATIONAL MODE SEQUENCING Once the parking card is unlocked (or the personal code is not required or set), the operational modes and the Adjustment modes are enabled.

OPERATIONAL MODE SEQUENCING WITH ONE CITY ENABLED For a parking card with only one city enabled, the Operational mode state diagram is shown in FIG. 3.

Note, City A is the default city in this mode. All charges against City A are applied to Bank 1.

Pushing the OFF key, aborts the mode, and enters the OFF STATE.

OPERATIONAL MODE SEQUENCING WITH TWO CITIES ENABLED For a parking card with two cities enabled, the Operational mode state diagram is shown in FIG. 4. When City A is selected, charges are applied to Bank 1. When City B is selected, charges are applied to Bank 2.

Pushing the OFF key, aborts the mode, and enters the OFF STATE.

CITY SELECTION MODE The City Selection Mode allows the user to select which city to charge the parking to. When City A is selected, parking is charged to City A and when City B is selected, parking is charged to City B. Note, the City Selection Mode will only occur if two cities are enabled.

When City A is selected and its associated bank is solvent or there are recharges available, the display in FIG.

13 is shown.

When City A is selected and its associated bank is insolvent and there are no recharges available, the display in FIG. 14 is shown.

When City B is selected and its associated bank is solvent or there are recharges available, the display in FIG.

15 is shown.

When City B is selected and its associated bank is insolvent and there are no recharges available, the display in FIG. 16 is shown.

Press the ON key to toggle between the selection of City A or City B. Press the OK key to accept the currently displayed city. Note, the OK key will function only when the flashing OK symbol is displayed. This prevents selecting cities with bankrupt banks when no recharges are available.

Press OFF to abort and turn parking card off.

Note, if both banks are broke and there are no recharges left, the state described in VOID RETURN DISPLAY is permanently entered at the time total bankruptcy occurs.

ZONE SELECTION MODE The Zone Selection Mode is used to select which parking zone the user wishes to park at. A typical display for this mode is shown in FIG. 17.

Use SELECT UP and SELECT DOWN keys to select the parking zone. All zones are selectable in either city, regardless of whether they are implemented. The time available at each zone will be displayed (shown here as 12 hours and 34 minutes). Use OK to order parking. Use OFF to abort and turn parking card off. Pressing ON, aborts the zone selection and changes to the City Selection Mode (only if two cities are enabled- otherwise it has no effect). Pressing SELECT DIGIT has no effect. The zone initially displayed, will be the last zone selected (for previous parking) or if no zone was previously parked at, zone A will be displayed. Zone upwards order is A, B, C, D, E, F, G, J, N, P, A, B,.... Zone downwards order is P, N, J, G, F, E, D, C, B, A, P, L,.... Note, not all zone letters will necessarily appear. Zones that are disabled will be skipped. Zones are disabled by setting their base charging rate to zero.

The display for zone selection also features the T symbol indicating that time available is being displayed.

Also featured is a flashing OK symbol, used to remind the user to press the OK key to order parking. See PARKING DISPLAYS for a description of the displays during active parking.

Note, the available parking time shown, represents the total parking time in the bank for this zone. When showing the total available parking time in the bank, the display will typically be in hours and if there are more hours of parking than 9999 hours, the display shows 9999 hours. If there are less than 100 hours of parking for this zone in the bank, the display will show hours and minutes separated by a colon. For example, 99: 59. The total time displayed is calculated from the zone's base rate times the medium parking factor.

If the bank associated with the selected city is broke, the display in FIG. 18 is shown, indicating that the user recharge the bank.

If the bank associated with the selected city is solvent but does not contain sufficient funds to begin parking at the selected zone (the selected zone's minimum charge exceeds the banks available funds) or if the selected zone is disabled (the selected zone is inhibited for ten minutes due to meter feed protection), the display in FIG. 19 is shown, indicating that the user cannot begin parking at this zone.

Zone selection is inhibited in these cases and the only keys that will respond to the user are OFF and ON.

Pressing the OFF key aborts the current mode and turns the parking card off. Pressing the ON key will cause the parking card to enter the City Selection Mode (only if two cities are enabled--otherwise the ON key has no effect).

The Zone Selection Mode features an additional display, placed between Zone A and Zone P. This display indicates the monetary value contained in the selected bank. FIGS. 20 and 21 are typical examples of this display.

For conditions where the monetary value is in dollars and exceeds 100, the display shown in FIG. 20 indicates $189 and for conditions where the monetary value is in dollars and under 100, the display shown in FIG. 21 indicates $99.94.

ADJUSTMENT MODE SEQUENCING The Adjustment Modes allow the parking card's user to examine the parking card's electronic serial number, adjust the parking card's time of day clock, recharge the parking card's banks, or change/set/disable the parking card's personal code.

Sequencing through the Adjustment modes depends upon whether there are two cities enabled or only one. FIG. 5 delineates the state diagram for single city case and

FIG. 6 delineates the state diagram for the two city case. In all Adjustment modes, pressing the ON key, cycles to the next adjustment mode and pressing the OFF key aborts the Adjustment modes and blanks the display.

SERIAL NUMBER DISPLAY MODE This mode displays the parking card's electronic serial number.

The initial display for this mode is shown in FIG.

22. After 4 seconds, the display will change to show the electronic serial number of the parking card. If the serial number is 12345678, the display shown in FIG. 23 will alternate every 4 seconds with the display shown in FIG. 24.

Use OFF to abort and turn parking card off. Pressing the ON key, aborts the serial number display and changes to the next sequential mode. Pressing SELECT UP, SELECT DOWN, and SELECT DIGIT have no effect. This mode will automatically exit to off in 30 seconds.

TIME ADJUST MODE The initial display for this mode is shown in FIG.

25.

Then, display will change to that shown in FIG. 26 after 4 seconds (note 11: 59 was chosen as an example) and the digits to adjust will be flashing. See below.

Use OFF to abort and turn parking card off. Pressing the ON key, aborts the time adjustment and changes to the next sequential mode.

The parking card includes a real time clock which runs continuously and is not adjustable by the user, but the user can enter an offset of a few minutes, either forward or backward, to take account of drift of the clock. The time displayed by the parking card is the current time indicated by the real time clock, as adjusted by the offset applied by the user.

The RAM stores a value for the number of days between a change to standard time and the next change to

daylight savings time and also stores the time difference between standard time and daylight savings time and a flag which indicates whether automatic switching between standard time and daylight savings time is enabled. If the flag is set, the controller counts down from a preset number of days from the previous change between standard and daylight saving time and when this count reaches zero, the real time clock is changed by the appropriate amount. If automatic switching is enabled, the user can offset the display time relative to the measured time by a few minutes.

What can be adjusted depends upon whether the flag is set or reset. If automatic switching of Standard/Savings Time is enabled, only the minute digits will flash. During this condition, the user presses SELECT UP or SELECT DOWN, to offset the clock's time, a minute for each keypress. Maximum offset is +7/-8 minutes. Once at either maximum positive offset or maximum negative offset, the clock cannot be further adjusted in the maximum's direction, no matter how many times the time adjustment is tried. Also note, the minute clock offset cannot be adjusted across an hour boundary.

If the automatic switching of the Standard/Savings Time is disabled, the user can also offset the hour by +/-2 hours. The user can switch between minute and hour offset by using the SELECT DIGIT key. At the start, the hours digits will be flashing, allowing the user to adjust the hour offset using the SELECT UP and SELECT DOWN keys. Pressing the SELECT DIGIT key, alternates between flashing minute digits and flashing hour digits.

As above, the minute digits are adjustable when the they are flashing. Just like the minute offset, once the hour offset is at either maximum positive offset or maximum negative offset, the clock cannot be further adjusted in the maximum's direction, no matter how many times the time adjustment is tried.

CITY A RECHARGE MODE The initial display for this mode is shown in FIG.

27. The letter A stands for the city and the number 0 stands for the recharge interval.

The display will change to FIG. 28 after 4 seconds with the selected digit flashing.

Adjust the display to the desired value as described below: Modify the selected digit's value by using SELECT UP and SELECT DOWN keys. Acceptable digits are 0 through 9 as well as the letters A, b, C, d, E, F. SELECT UP, at each keypress, causes the flashing digit to increment in the order 3,4,5,6,7,8,9, A, b, C, d, E, F, 0,1,2,...).

SELECT DOWN, at each keypress, causes the flashing digit to decrement in the order (F, E, d, C, b, A, F, E, d...).

After setting selected digit (the flashing digit) to the value desired, select the next digit to be modified by using the SELECT DIGIT key. The SELECT DIGIT key, each time it is pressed, moves the selected digit (the flashing digit) right one digit. If at the rightmost digit on the LCD display, pressing the SELECT DIGIT key, selects the leftmost digit of the four digit set.

In this manner, the digits can be adjusted to display a desired group of four characters.

After entering in a recharge code, the OK key is used to validate it. The OK key will validate the recharge code only when all four digits have been modified.

After entering in a recharge code, the OK key is used to validate it. The OK key will validate the recharge code only when all four digits have been modified. Note, the OK symbol will begin to flash when validation is available. Press the OK key until either a PASS or FAIL is displayed.

Note, the RECHARGE MODE is only displayed when there are recharges available and when the associated bank is

sufficiently low so that it will not overflow when recharged.

The associated displays for City A Pass/Fail are shown in FIGS. 29 and 30 respectively.

After a successful validation, press the OK key or ON key to continue to the next adjustment mode. After an unsuccessful validation, press the OK key to retry or press the ON key to continue to the next adjustment mode.

CITY B RECHARGE MODE The initial display for this mode is shown in FIG.

31. The letter B stands for the city and the number 0 stands for the recharge interval.

The display will change to FIG. 32 after 4 seconds with the selected digit flashing.

Adjust the display to the desired value as described above.

Validate the recharge code word as described above.

The associated Pass/Fail displays for City B are shown in FIGS. 33 and 34 respectively.

After a successful validation, press the OK key or ON key to continue to the next adjustment mode. After an unsuccessful validation, press the OK key to retry or press the ON key to continue to the next adjustment mode.

Note, the RECHARGE MODE is only displayed when there are recharges available and when the associated bank is sufficiently low so that it will not overflow when recharged.

RECHARGE MODE (single city) The initial display for this mode is shown in FIG.

35, where the number 0 stands for the recharge interval.

The display will change to FIG. 36 after 4 seconds with the selected digit flashing.

Adjust the display to the desired value as described above.

Validate the recharge code word as described above.

The associated Pass/Fail displays are shown in FIGS. 37 and 38 respectively.

After a successful validation, press the OK key or ON key to continue to the next adjustment mode. After an unsuccessful validation, press the OK key to retry or press the ON key to continue to the next adjustment mode.

Note, the RECHARGE MODE is only displayed when there are recharges available and when the associated bank is sufficiently low so that it will not overflow when recharged.

SET PERSONAL CODE MODE The initial display for this mode is shown in FIG.

39 and will change to FIG. 40 after 4 seconds, with the selected digit flashing (initially the first digit).

Adjust the display to the desired value as described above under recharging.

After entering in a personal code, the OK key is used to store it. The OK key will enter the personal code only when all four digits have been modified and then only if the OK key is held down for 2 seconds. The display shown in FIG. 41 is displayed upon successful personal code entry. The display will remain for 30 seconds or until the ON key, OK key or the OFF key is pressed.

Pressing the ON key, before personal code entry completion, cycles to the next adjustment mode. Not pressing OK for 2 complete seconds restarts the entry back at the code entry display of the personal code adjustment. Pressing the OFF key before personal code completion, aborts the process and blanks the display.

Note, the personal code'FFFF'has special meaning.

On parking cards not required by the municipality to have a personal code, the special code allows the user to reset the parking card back to the state of'No Personal Code Entered'. This will allow users to disable the use of a personal code or change the code by first disabling

it and then re-entering a new code. The code'FFFF'has only a special meaning when setting the personal code. If a personal code has been accepted, the user can only get to the SET PERSONAL CODE MODE (or any other modes) by first entering the accepted personal code.

STATUS DISPLAYS VOID RETURN DISPLAY If the parking card's banks are totally broke and there are no more recharges left for either bank, the display shown in FIG. 42 will be given at all times.

This state can only be removed by resetting the parking card.

INITIAL DISPLAY If the parking card has been reset or has lost power, the display will default to all segments lit, as shown in FIG. 43.

This display can only be removed by successful initial programming of the parking card.

WARNING DISPLAYS BATTERY LOW WARNING DISPLAY The parking card has a built-in battery test that is run once per day at 02: 00 am. If the battery in the parking card tests below the warning threshold (2.67 volts), the battery warning display is shown in lieu of a blank display when the parking card is off. This display warns the user to turn in his parking card before it dies (usually after several months of warning). This will allow the user to get credit for his remaining bank and order a new parking card in sufficient time to prevent interruption in parking. This warning display will alternate with other warning displays on a four second interval. The battery low warning display is shown in FIG. 44.

PARKING DISPLAYS The following sub-sections delineate the various displays and sequences of displays that occur after parking is OK'd for a zone.

PARKING DISPLAY SEQUENCE Once in Parking Mode, the parking card will display the following repetitive sequence of displays: PARKING TIME DISPLAY 4 seconds TIME OF DAY DISPLAY 4 seconds CITY DISPLAY 4 seconds AUTHENTICATION CODE DISPLAY 4 seconds PARKING TIME DISPLAYS The Parking displays vary depending upon whether the parking card is in the Standby, Active, or Overtime modes of parking.

ACTIVE PARKING DISPLAY An example for the Active parking display for zone B is shown in FIG. 45.

There are a few things to note here. First, the P symbol in the display is flashing. If the time zone is unlimited, the time displayed (shown here as 02: 58), is the time parked. If the zone has a time limit, the time displayed represents the time remaining from the zone's time limit.

Another feature that shows up in zones with time limits is the shrinking of the word'PARKULATOR'at the bottom of the display.'PARKULATOR'will shrink in proportion to the ratio (time parked/time limit). By shrink it is meant that the letters at the end of the word will begin to drop off. The size of the word is related to time left approximately as follows: PARKULATOR 90% time left PARKULATO 80% time left

PARKULAT 70% time left PARKULA 60% time left PARKUL 50% time left PARK 40% time left PAR 30% time left PA 20% time left p 10% time left STANDBY PARKING DISPLAY An example for the Standby parking display for zone B is shown in FIG. 46.

In this display, the P symbol in the display is flashing. Note, this display represents that the parking card is in Park mode but not charging due to the fact that the zone is free at this particular time. Standby and Active parking are automatically entered depending upon the time of day and the zone's settings.

OVERTIME PARKING DISPLAY WITHIN OT LIMIT An example for the Overtime (within OT Limit) parking display for zone B is shown in FIG. 47.

In this display, the P symbol and the word 'PARKULATOR'are flashing. The negative time displayed (shown here as-00: 10), is the time parked in overtime.

OVERTIME PARKING DISPLAY BEYOND OT LIMIT An example for the Overtime (beyond OT Limit) parking display for zone B is shown in FIG. 48.

In this display, the P symbol and the word 'PARKULATOR'are flashing. The negative time displayed (shown here as-00: 16), is the time parked in overtime.

The difference between this display and the within OT Limit display is that the word PARKULATOR is split and flashes alternately. That is: PARKULATOR PARKULATOR PARKULATOR etc.

The BOLD type indicates lit and the normal type is unlit.

CITY DISPLAY When parking, the city as well as the zone must be displayed. The City display is shown in FIG. 49.

In this display, the P symbol is flashing. The word PARKULATOR remains as it was for the parking display modes. That is if it was shrinking or flashing, it is doing the same in this display.

TIME OF DAY DISPLAY The Time of Day display is shown in FIG. 50.

The word PARKULATOR remains as it was for the parking display modes. That is if it was shrinking or flashing, it is doing the same in this display.

AUTHENTICATION CODE DISPLAY The Authentication Code display is shown in FIG. 51.

The word PARKULATOR remains as it was for the parking display modes. That is if it was shrinking or flashing, it is doing the same in this display.

AUTHENTICATION CODE The parking card displays an Authentication Code for 4 seconds every 12 seconds. The purpose of this code is to validate the parking card as genuine. The code output will change on a hourly basis, at the hour, according to the algorithm shown in FIG. 53. The municipality can authenticate the parking card by verifying that its authentication code matches the code output by other active parking cards during the same hour. Authentic parking cards issued for parking in a given municipality should all output the same code. If a parking card is found with the wrong code, the owner can be notified to turn W his/her parking card in for replacement (assuming he/she owns one) and the printed

serial number on the parking card can be verified as authentic.

AUTO START/STOP If a user activates the parking card in a zone, which at the time is free, the parking card will enter the Standby mode. At a later time, when the zone transitions to charging, the parking card, if still active, will automatically enter the Active Parking mode. Later if the zone transitions back to a free zone, one of two possible actions may occur. The parking card will again enter the Standby mode if the zone selected is not a time limited zone and the zone's auto start/stop option is set. The parking card will automatically shut- off if the zone selected has a time limit or the zone's auto start/stop option is reset. See FIG. 52 for a flow chart of this feature.

SOLAR CELL BATTERY ASSIST Operating current for the in-car parking meter shown in FIG. 1 is supplied by a rechargeable battery 44.

An in-car personal parking meter may often be subject to extremely high temperatures (being on the inside of an automobile on a sunny day). These high temperatures can cause battery operated electronics to draw a much higher current than at normal ambient temperature (typically about 18° C). For example, a microprocessor that normally draws 1 uA of current at room temperature may draw as much as 15-20 uA of current at 80° C. This twenty-fold increase in current draw can greatly shorten the battery life.

On the other hand, an in-car parking meter must be placed so that it is easily visible in the car and it will normally be subjected to these high temperatures only in bright sunlight conditions. The placement of the in-car parking meter allows the meter to be exposed to both direct and indirect sunlight. A ceramic solar cell of a reasonable size, a half square inch for instance,

can produce at least about 50 uA of current when exposed to bright daylight. Therefore, the in-car parking meter may be provided with a ceramic solar cell 48 or similar device, which can supply sufficient current to easily offset the high current draw of most low power microprocessors in these high temperature conditions.

PARKING CARD PARAMETER UPDATE Besides the ability to recharge the personal parking meter's time bank, it may also be necessary from time to time to change some of the parking parameters. Such a change may be more complicated than could easily be handled by a member of the general public since it might consist of entering long strings of numbers. The parking card is designed to be updated in the field by the authority in charge of the parking card. Parameter update is allowed by the use of special interface hardware and the entry of a update parameter code word, specific to each parking card.

Additionally, the concept of a remote recharge capability is important.

One advantage of doing this remotely, is that the user is not inconvenienced by the need to transport his parking meter to a reprogramming location, or mail it in.

One of many possible ways to perform this remote recharge follows: The user calls a central recharge phone number, enters his serial number via touch tones and over the telephone the unit is remotely downloaded with new parking parameters. This could be accomplished by means of an audio transducer within the parking meter, that decodes the tones being sent over the telephone and translates them into a serial data stream. Of course, adequate error checking would be provided and the parking meter, via its display, could indicate the success of the operation. Multiple attempts could be allowed; the user being instructed over the phone on the process. The user

could also communicate back recharge status to the center by using the touch tone keys on his/her phone.