Electronic pavement sign, computing system, computer program, method for charging a battery of an electronic pavement sign, and method for adjusting a brightness of an electronic pavement sign

Abstract

An electronic pavement sign comprising an electronic display panel configured to present visual information to users; a battery configured to power the electronic display panel; and a battery management system configured to determine a battery voltage of the battery; to control, based on the determined battery voltage, a charging of the battery; to determine that the battery is in a deep discharge state if the battery voltage is below a voltage threshold value indicative of at least one cell of the battery having a cell voltage below a minimum cell voltage; and to restore, if it is determined that the battery is in a deep discharge state, the battery from the deep discharge state to a normal state by applying in intervals a non-zero charging voltage and / or a non-zero charging current to the battery.

Description

[0001] ELECTRONIC PAVEMENT SIGN, COMPUTING SYSTEM, COMPUTER PROGRAM, METHOD FOR CHARGING A BATTERY OF AN ELECTRONIC PAVEMENT SIGN, AND METHOD FOR ADJUSTING A BRIGHTNESS OF AN ELECTRONIC PAVEMENT SIGN

[0002] Field of the invention

[0003] The present invention relates to an electronic pavement sign. The invention further relates to a computing system and a computer program, both associated with the electronic pavement sign. Furthermore, the invention relates to a method for charging a battery of an electronic pavement sign and to a method for adjusting a brightness of an electronic pavement sign.

[0004] Background of the invention

[0005] Traditional pavement signs have been used extensively in various business environments to display important information or promotional content to the public. They serve a critical role in providing visual cues, directions, and advertisements to both pedestrians and drivers. However, these conventional signs usually rely on printed or hand-written displays which are static, labor- intensive to change, and limited in their ability to engage viewers.

[0006] With the advancement of digital technology, electronic signs have started to replace traditional ones in many contexts, such as billboards and storefront signs, due to their dynamic, customizable and engaging nature. These electronic signs typically utilize LED, LCD or other electronic display technologies.

[0007] However, current electronic sign solutions are generally not suitable for pavement use due to various reasons such as difficulty in portability, higher costs, and / or high energy consumption.

[0008] Hence, there is a need for an advanced, efficient, and robust electronic pavement sign that not only improves upon the limitations of traditional signs but also addresses the specific challenges associated with outdoor and pavement use.

[0009] Summary of the invention

[0010] It is an object of the present invention to provide an improved electronic pavement sign addressing one or more shortcomings of existing systems, or at least provide an alternative.

[0011] In a first aspect of the present invention an electronic pavement sign is provided, comprising: an electronic display panel configured to present visual information to users; a battery configured to power the electronic display panel; a battery management system configured to: o determine a battery voltage of the battery; and o control, based on the determined battery voltage, a charging of the battery.

[0012] The electronic pavement sign is an electronic and / or digital sign typically placed on the pavement or sidewalk near the entrance of a business establishment. Alternatively, a pavement sign may be called a sidewalk sign, street display or walkway sign. The electronic pavement sign may comprise a base or foot configured to support the electronic display panel. The electronic display panel may be placed on top of the base. The battery may be, at least partly, comprised by the base. The electronic display panel may comprise or use LCD, LED, e-ink or other display technologies. The height and / or width of the electronic display panel may be larger than 1 meter. The electronic display panel may comprise a display control system for controlling the electronic display panel. The electronic display panel is powered by the battery. The battery may be based on various technologies. The battery may be a lead-acid, lithium-ion, lithium-polymer, nickel-cadmium, nickel- metal hydride, alkaline, zinc-carbon or a solid-state battery. Using other battery technologies is however also possible. The battery may store at least 50 Ah with a normal output voltage of around 24V. However, the present invention is not limited to a particular battery capacity and / or nominal voltage. The battery may be configured to power the electronic display panel for at least 8 hours, preferably for at least 10 hours. However, longer hours may also be possible. During a time that the electronic pavement sign is switched on, the amount of energy and charge stored in the battery reduces. Particularly, the electronic display panel may consume a majority of the energy stored in the battery. The battery management system is configured to determine the battery voltage which may be indicative of the remaining amount of energy and / or charge. The battery management system may further be configured to determine a cell voltage of one or more cells comprised by the battery. Preferably, the battery management system is configured to determine the cell voltage of all cells comprised by the battery. The battery management system may further be configured to determine charging and discharging currents associated with the battery. Also based on the determined charging and discharging currents, the battery management may determine the remaining amount of energy and / or charge in the battery. Determining the battery voltage may be done by a voltage meter. Such voltage meter may be comprised by the battery management system, or may be a separate device connected with the battery and the battery management system. Furthermore, the electronic pavement sign may comprise a battery charger or simply referred to as charger, connected with the battery and the battery management system, and configured to charge the battery. Alternatively, the battery charger may be comprised by the battery management system. Electronics comprised by the battery management system may at least partly be comprised by the battery and / or may at least partly be comprised by the battery charger. The battery charger may further be provided with a plug or socket for connecting the battery charger to the mains of the electricity grid, and optionally a power cable for connecting the plug or socket to mains. The battery management system may be configured to control a charging of the battery by the battery charger, preferably based on the determined battery voltage.

[0013] In an embodiment, the battery management system further is configured to: o determine that the battery is in a deep discharge state; and o restore, if it is determined that the battery is in a deep discharge state, the battery from the deep discharge state to a normal state.

[0014] In various portable devices, batteries may be configured to stop providing power if the battery voltage becomes too low, e.g. if the battery voltage is below a so-called cut-off voltage. To prevent a full discharge of the battery and / or to prevent that a battery enters a deep discharge state, in the art a relative high, and therefore conservative, cut-off voltage may be used. Such relative high cut-off voltage ensures that the battery remains in the normal state, wherein the battery voltage remains sufficiently high to enable an accurate determining of the battery voltage and to normally recharge the battery. Le., the normal state of the battery refers to a state wherein the battery is not in the deep discharge state, and wherein the battery may charge and / or discharge normally. A high cut-off voltage is helpful to lengthen the life time of the battery and is often chosen in portable electronics. However, for electronic pavement signs a high cut-off voltage is less suitable as it would imply a reduced running time of the electronic pavement sign per battery charge. In addition, the use of a high cut-off voltage for a battery of an electronic pavement sign may imply higher battery costs and / or using a bigger and / or heavier battery. Furthermore, for electronic pavement signs it is desirable that the electronic display panel remains powered as long as needed from a business perspective, even if it may cause an additional discharge of the battery beyond a typical cut-off voltage. As a result, the battery may enter a deep discharge state. The deep discharge state may be cell-protecting, i.e. it may prevent further deterioration of the battery cells. Such deep discharge state may refer to a condition where the battery is discharged to a very low level, often associated with a low cell voltage. For example, such low cell voltage may be 2,8 Volt for LFP04 cells. At this voltage the cell may have 5% of 10% remaining capacity but further discharging will damage the cell and deteriorate the potential capacity of the cell. The battery management system is configured to determine that one or multiple cells in the battery are in the deep discharge state. The battery management system may determine that the battery is in the deep discharge state based on one, a plurality or all of the individually determined cell voltages. The battery management system may be configured to provide a zero, or substantially zero, output voltage if the battery is in the deep discharge state. Prior to the present invention, electronic pavement signs did not provide a user friendly and reliable implementation that provides the possibility to restore the battery from the deep discharge state. According to the present embodiment of the present invention, the battery management system in combination with the charger is configured to wake up (or jump start) and restore, if it is determined that the battery is in a deep discharge state, the battery from the deep discharge state to a normal state. The battery management system may do so, by provided charging currents and / or charging voltages to the battery. In particular, the battery management system may be configured to provide charging currents and / or charging voltages if the determined battery voltage is zero, substantially zero, or below the voltage threshold value detailed above. Therefore, an electronic pavement sign according to the invention may be equipped with a smaller battery than an electronic pavement sign without a capability to restore the battery from a deep discharge state. Conventional chargers in electronic pavement signs may not be able to provide a charging current if the determined battery voltage is zero.

[0015] In a particular embodiment, the battery management system is configured to detect a deep- discharged battery with a zero-voltage or almost zero-voltage battery connected to the electronic display panel and to jump-start or wake up the battery until the battery is charged from deep- discharged to a normal state. Conventional battery management systems are configured to power off equipment when battery voltage is below a cut-off voltage thus actively preventing the battery from entering the deep discharge state. In contrast, the battery management system of the present invention is configured to allow, at least at some instances, a discharge of the battery into its deep discharge state, thereby increasing the operating time of the electronic pavement sign.

[0016] In an embodiment, the battery management system is configured to determine that the battery is in a deep discharge state if the battery voltage is below a voltage threshold value indicative of at least one cell of the battery having a cell voltage below a minimum cell voltage.

[0017] Cells or battery cells comprised by the battery have a minimum cell voltage, which depends on the type of battery technology. The minimum cell voltage is an inherent property of a battery cell, and represents the cell voltage at which further discharge of the cell causes damage to the cell. For lithium-ion batteries the minimum cell voltage typically is within the range of 2.4 volt to 3.0 volt. The battery voltage depends on the configuration and arrangement of the battery cells comprised by the battery. At the voltage threshold value a cell voltage of at least one battery cell of the battery is below a minimum cell voltage. The battery voltage may depend on the number of battery cell placed in series. The voltage threshold value may be set to a level indicative of at least one cell voltage being below the minimum cell voltage. For example, if the determined battery voltage is representative of the sum of cell voltages, e.g. when the cells of the battery are connected in series, the voltage threshold value may be set to the sum of the minimum cell voltages of the cells making up the battery. If the battery voltage is below the voltage threshold value, the determined battery voltage may be zero. For example, if the battery voltage is below 18 volt, the determined battery voltage may be zero as some batteries may provide a zero output voltage is the battery is in the deep discharge state.

[0018] In an embodiment, the battery management system is configured to restore, if it is determined that the battery is in a deep discharge state, the battery from the deep discharge state to a normal state by applying in intervals a non-zero charging voltage and / or a non-zero charging current to the battery.

[0019] To restore the battery to a normal state, wherein the normal state is a state wherein the battery is not in the deep discharge state, the battery management system is configured to apply a non-zero charging voltage and / or a non-zero charging current. In particular, the battery management system is configured to do so in intervals. Providing the charging voltages and / or currents in intervals may enable the battery and / or the battery cells to recover from the deep discharge state in between the intervals. In particular, in between the intervals chemical process may occur that are associated with an increase of the battery voltage and / or cell voltage.

[0020] In an embodiment, during the restoring from the deep discharge state, the charging current is limited to a current limit that is lower, preferably at least 15% lower, than the charging current used for charging the battery when the battery is in a normal state.

[0021] In an embodiment, at least one of the intervals of applying the non-zero charging voltage and / or a non-zero charging current to the battery is at least one second.

[0022] The length of an interval may be based on the specific battery comprised by the electronic pavement sign. However, the time in between the intervals may be sufficiently long to allow the cell voltage to recover. Preferably, at least one interval lasts at least one second. More preferably, a plurality of intervals lasts at least one second.

[0023] In an embodiment, the battery management system is configured to:

[0024] • determine the battery voltage during the restoring from the deep discharge state, preferably in between the intervals;

[0025] • stop restoring the battery from the deep discharge state if the determined battery voltage is above the voltage threshold value, preferably at least 0.1 volt above the voltage threshold value; and stop restoring the battery from the deep discharge state after a predetermined number of intervals and / or after a predetermined amount of charging time.

[0026] To determine whether the battery is recovered from the deep discharge state, the battery management system is configured to determine the battery voltage during the restoring of the battery. The battery voltage may be determined during providing the charging current and / or charging voltage. Preferably however, the voltage is determined in between the intervals such that the determined voltage of the battery is not affected by the charging voltage. A time between two intervals may be at least one second, preferably at least two seconds. Furthermore, the time between two intervals may be less than one minute, preferably less than 10 or 5 seconds. Once the determined battery voltage is sufficiently high, e.g. above the voltage threshold value, the restoring of the battery is stopped and the normal charging may continue. To ensure that the battery is sufficiently restored, the restoring may stop if the determined battery voltage is a predetermined voltage above the voltage threshold value, e.g. 0.1 volt. In case the restoring of the battery is not working, i.e. if after a predetermined amount of time or intervals the battery voltage is not sufficiently above the voltage threshold value, the battery management system is configured to stop the restoring of the battery. Additionally, the battery management system may initiate a communication of a failed restoring to a user.

[0027] In an embodiment, the predetermined number of intervals is at least 10 and / or wherein the predetermined amount of charging time is at least 10 seconds.

[0028] The number of intervals may be predetermined and generally depends on the type of battery. The number of intervals may also be associated with the length of an interval, and / or a time in between the intervals. Similarly, a total amount of charging time in which the battery management system attempts to restore the battery from the deep discharge state may be predetermined. For example, the predetermined amount of charging time is 10 seconds, but a charging time of minutes or more is also possible. The charging time may be less than one hour.

[0029] In an embodiment, the electronic pavement sign comprises at least one sensor selected from a group comprising: an ambient light sensor, a temperature sensor and a humidity sensor.

[0030] The electronic pavement sign may comprise various sensors to facilitate the operating and / or the restoring of the battery. For example, the charging current, charging voltage, the length of an interval, and a time between two intervals may each depend on a determined temperature and / or humidity, determined by the temperature sensor and / or humidity sensor respectively. The temperature sensor and the humidity sensor may be connected with the battery management system. In an embodiment, the electronic pavement sign comprises the ambient light sensor, wherein the electronic pavement sign is configured to control a brightness of the electronic display panel based on an ambient light determined by the ambient light sensor.

[0031] In case an environment of the electronic pavement sign is relatively bright, the brightness of the electronic display panel may be controlled to be relatively bright as well, to ensure a good visibility to the user. Additionally, or alternatively, the electronic pavement sign may be configured to control the brightness of the electronic display panel based on the determined battery voltage. The ambient light sensor may be connected with the battery management system and / or with the electronic display panel.

[0032] In an embodiment, the electronic pavement sign is configured to:

[0033] • determine a stored energy and / or charge in the battery;

[0034] • determine an actual time;

[0035] • determine a switching-off time associated with an expected time in which the electronic pavement sign will be switched off;

[0036] • determine a remaining on-time as a difference between the actual time and the switching- off time;

[0037] • control a brightness of the electronic display panel to control a power consumption of the electronic display panel such that a consumed energy and / or charge by the electronic pavement sign during the remaining on-time is less than or equal to the stored energy and / or charge in the battery.

[0038] The electronic pavement sign may ensure that the electronic display panel is powered until the switching-off time by controlling or adjusting the brightness. For example, if the stored energy or charge in the battery is not sufficient to keep the electronic display panel on with a first brightness, the brightness of the electronic display panel may be set to a second brightness, wherein the second brightness is lower than the first brightness. The electronic display panel may comprise a plurality of different brightness levels. Each particular brightness level has an expected power consumption associated with it. In this way, the power consumption of the electronic display panel may be controlled by controlling the brightness. For example, if the remaining energy in the battery is X kWh, and the remaining on time is Y hours, then the brightness must be selected or controlled such that the electronic display panel may not consume more than X / Y kW. In case other power consumption not related to the brightness of the electronic display panel is Z kW, the brightness must be controlled such that the brightness related power consumption is not more than X / Y - Z. In an embodiment, the switching-off time is predetermined or the electronic pavement sign is configured to estimate the switching-off time based on previous switching-off times.

[0039] The time when the electronic pavement sign is switched off, i.e. the switching-off time, may be predetermined. For example, the switching-off time is based on the opening hours of a business. For example, the switching-off time may be set at 18:00. The switching-off time may differ for different days. Alternatively, the electronic pavement sign may learn the switching-off time based on previous times the electronic pavement sign has been switched-off. For example, the estimated switching-off time may be set as the average of the previous 5 days. Alternatively, more elaborate machine-learning approaches may be used to estimate the switching-off time based on previous switching-off times and possible also based on other data.

[0040] In an embodiment, the electronic pavement sign is configured to:

[0041] • determine if the battery management system charges the battery;

[0042] • prevent, if it is determined that the battery management system does not charge the battery, a switching-on of the electronic display panel if the battery voltage increases to above the voltage threshold value.

[0043] The electronic pavement sign may switch off if the battery voltage drops below the voltage threshold value. Once the electronic pavement sign is switched off, the battery voltage may rise again due the physical and / or chemical processes in the battery or battery cells. To avoid on-off chattering, the electronic pavement sign does not switch on if the battery voltage increases to above the voltage threshold value if the battery is not being charged.

[0044] In an embodiment, the electronic pavement sign, further comprises a wireless communication module connected to the battery management system, wherein the wireless communication module is configured to transmit battery information to a remote computing system, wherein preferably the battery information comprises information representative of the determined battery voltage.

[0045] The electronic pavement sign may comprise the wireless communication module to transfer information on the electronic pavement sign. For example, the information may comprise battery information. However, the transmitted information may further comprise other data determined or sensed by the electronic pavement sign, such as switching-on time, switching-off time, temperature, brightness, etc. The remote computing system may be configured to receive the information, and preferably to provide at least part of the received information to a user. In an embodiment, the battery management system further is configured to determine a health status of the battery associated with operating parameters of the battery, and wherein the electronic pavement sign further comprises a wireless communication module connected to the battery management system, wherein the wireless communication module is configured to transmit information representative of the determined health status to a remote computing system, preferably if the determined health status indicates a decreased and / or low health of the battery. The health of the battery may also be referred to as state of health (SOH) of the battery.

[0046] Submitting the health status, preferably including one or more parameters indicative of the health status, enables the computing system or a user interacting with the computing system to act on a possible low or decreasing health status of the battery. For example, the health status may comprise information indicative of the energy or charge capacity of the battery. Additionally or alternatively, the health status may comprise information indicative of the frequency that the battery enters a deep discharge state. Based on the health status, service actions may be initiated to improve the electronic pavement sign, for example, by exchanging the battery for another battery.

[0047] In an embodiment, the electronic pavement sign is configured to power-off the communication module if the battery is in and / or enters the deep discharge state.

[0048] If the battery is in the deep discharge state, the battery may not power the communication module anymore. Alternatively, the communication module may comprise a communication module battery independent of the battery, such that for example the health status may still be submitted, even if the battery is in the deep discharge state.

[0049] In further embodiments, the electronic pavement sign comprises features of one or more embodiments of the electronic pavements signs according to the first aspect of the invention. In particular, the electronic pavement sign may be configured to control the brightness, without the battery management system being configured to restore the battery from a deep discharge state. For example, an aspect of the invention is the following:

[0050] In a second aspect of the present invention an electronic pavement sign is provided, comprising:

[0051] • an electronic display panel configured to present visual information to users;

[0052] • a battery configured to power the electronic display panel;

[0053] • a battery management system configured to: o determine a battery voltage of the battery; and o control, based on the determined battery voltage, a charging of the battery; and an ambient light sensor, wherein the electronic pavement sign is configured to control a brightness of the electronic display panel based on an ambient light determined by the ambient light sensor.

[0054] Preferably, the electronic pavement sign according to the second aspect of the present invention is configured to control a brightness of the electronic display panel to control a power consumption of the electronic display panel such that a consumed energy and / or charge by the electronic pavement sign during the remaining on-time is less than or equal to the stored energy and / or charge in the battery.

[0055] The second aspect may further be extended with any of the features detailed above for the first aspect of the invention.

[0056] In a third aspect of the present invention a computing system is provided, configured to wirelessly receive battery information from the electronic pavement sign according to the first and / or second aspect of the invention, wherein the computing system is configured to determine, based on the battery information, whether the battery is in the deep discharge state.

[0057] Preferably, the battery information is indicative of the battery voltage. The computer system may comprise a hard drive wherein battery parameters associated with an electronic pavement sign are stored. The computing system may determine whether the battery is in the deep charge by analyzing received battery information and / or received battery voltages.

[0058] In an embodiment, the computing system is configured to determine that the battery is in the deep discharge state if the determined battery voltage is decreasing over time and the last received determined battery voltage is less than 0.3, preferably 0.2 or more preferably 0.1 volt above the voltage threshold value.

[0059] As an example, the computing system may determine that the battery is in the deep discharge state if the battery voltage is decreasing and that the last battery voltage is only slightly higher than a voltage wherein the battery enters the deep discharge state.

[0060] In a fourth aspect of the present invention a computer program is provided, configured to:

[0061] • receive battery information representative of the determined battery voltage of an electronic pavement sign according to the first aspect of the invention;

[0062] • determine, based on the received battery information, whether the battery is in the deep discharge state. The computer program may determine whether the battery is in the deep discharge state as detailed in the description of the third aspect of the present invention. In particular, the computer program may run at least partly on a processor comprised by a computing system.

[0063] In a fifth aspect of the present invention, a method for charging a battery of an electronic pavement sign is provided, comprising the steps of: a) determining a battery voltage of the battery; b) controlling, based on the determined battery voltage, a charging of the battery; c) determining that the battery is in a deep discharge state; and d) restoring, if it is determined that the battery is in a deep discharge state, the battery from the deep discharge state to a normal state.

[0064] In an embodiment, the method comprises a step of determining that the battery is in a deep discharge state if the battery voltage is below a voltage threshold value indicative of at least one cell of the battery having a cell voltage below a minimum cell voltage.

[0065] In an embodiment, the method comprises a step of restoring, if it is determined that the battery is in a deep discharge state, the battery from the deep discharge state to a normal state by applying in intervals a non-zero charging voltage and / or a non-zero charging current to the battery.

[0066] In a sixth aspect of the present invention, a method for adjusting a brightness of an electronic pavement sign is provided, comprising the steps of: a) determining a stored energy and / or charge in the battery; b) determining an actual time; c) determining a switching-off time associated with an expected time in which the electronic pavement sign will be switched off; d) determining a remaining on-time as a difference between the actual time and the switching- off time; e) controlling a brightness of the electronic display panel to control a power consumption of the electronic display panel such that a consumed energy and / or charge by the electronic pavement sign during the remaining on-time is less than or equal to the stored energy and / or charge in the battery.

[0067] The present invention further relates to the following aspect, described by clauses:

[0068] Clause 1: Electronic pavement sign, comprising: an electronic display panel configured to present visual information to users; a battery configured to power the electronic display panel; a battery management system configured to: o determine a battery voltage of the battery; o control, based on the determined battery voltage, a charging of the battery;

[0069] • at least one sensor selected from a group comprising: an ambient light sensor, a temperature sensor and a humidity sensor.

[0070] Clause 2: Electronic pavement sign according to clause 1, comprising the ambient light sensor, wherein the electronic pavement sign is configured to control a brightness of the electronic display panel based on an ambient light determined by the ambient light sensor.

[0071] Clause 3: Electronic pavement sign according to clause 2, configured to:

[0072] • determine a stored energy and / or charge in the battery;

[0073] • determine an actual time;

[0074] • determine a switching-off time associated with an expected time in which the electronic pavement sign will be switched off;

[0075] • determine a remaining on-time as a difference between the actual time and the switching- off time;

[0076] • control a brightness of the electronic display panel to control a power consumption of the electronic display panel such that a consumed energy and / or charge by the electronic pavement sign during the remaining on-time is less than or equal to the stored energy and / or charge in the battery.

[0077] Clause 4: Electronic pavement sign according to clause 3, wherein the switching-off time is predetermined or wherein electronic pavement sign is configured to estimate the switching-off time based on previous switching-off times.

[0078] These and other aspects of the invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts. Brief descriptions of the drawings.

[0079] Brief description of the drawings

[0080] Figure la depicts, in a schematic view, a first embodiment of an electronic pavement sign.

[0081] Figure lb depicts, in a schematic view, a second embodiment of an electronic pavement sign. Figure 2 depicts, in a schematic view, a third embodiment of an electronic pavement sign, additionally comprising an ambient light sensor.

[0082] Figure 3 depicts, in a schematic view, a fourth embodiment of an electronic pavement sign, and an embodiment of a computing system located remotely from the electronic pavement sign.

[0083] Figure 4 depicts a voltage curve associated with a battery comprised by an embodiment of an electronic pavement sign.

[0084] Figure 5 illustrates charging intervals to restore the battery from a deep discharge state.

[0085] Figure 6 depicts a flow diagram of steps of an embodiment of a method for charging a battery of an electronic pavement sign.

[0086] Figure 7 depicts a flow diagram of steps of an embodiment of a method for adjusting a brightness of an electronic pavement sign.

[0087] Detailed description of embodiments

[0088] Figure la depicts, in a schematic view, a first embodiment of an electronic pavement sign 101. The electronic pavement sign 101 comprises an electronic display panel 103 configured to present visual information to users, such as promotions, prices and activities. Users are typically pedestrians passing by the electronic pavement sign 101, which is typically placed in front of a store. The electronic pavement sign 101 comprises a battery 105 which provides the required energy to power the electronic pavement sign 101 if the electronic pavement sign 101 is not connected with the main electricity network. In this embodiment, the battery has a capacity of 96Ah with a nominal voltage of 25.2 volt. The battery 105 is configured to power at least the electronic display panel 103. Besides the electronic display panel 103, the electronic pavement sign may comprise other components that may be powered by the battery 105, such as a computation and / or communication module. The display panel has a size a height of 1189 mm and a width of 841 mm, i.e. it has a typical A0 format. However, other formats are of course possible. Preferably, the display has a diagonal of at least 1 meter such that information is visible from a larger distance, for example from the other side of a road. The electronic display panel 103 is connected with a display power cable 115 to the battery 105. Additionally, a battery management system 107 is present. Both, the battery 105 and the battery management system 107 are arranged within the base 109 of the electronic pavement sign 101. The battery management system 107 is configured to determine a battery voltage of the battery 105. The battery management system 107 is connected with the battery 105 via a power cable 117 and a communication cable 119. In other embodiments, the power cable 117 and the communication cable 119 may be a single cable. The communication cable 119 may be used to exchange information between the battery management system 107 and the battery 105. The power cable 117 may be used to provide charging power to the battery 105, when the electronic pavement sign 101 is connected to a mains via a charging cable 111. In the embodiment depicted in Figure la, a charger 113 is comprised by, and is within, the battery management system 107. The charger is configured to charge the battery. The battery management system 107 is configured to control, based on the determined battery voltage, a charging of the battery 105. The battery management system 107 may do so by controlling the charger 113. In this embodiment a charger 113 is used with a maximum output power of 300 Watt. The operating temperature of the charger 113 is between -30 degree and 40 degree Celsius, such that the charger is suitable for outdoor use. The battery management system 107 is configured to determine or measure a voltage of the battery. In particular, the battery management system 107 is configured to determine a voltage of individual cells in the battery. Based on said voltage measurement, the battery management system 107 is configured to determine that the battery 105 is in a deep discharge state if the battery voltage is below a voltage threshold value indicative of at least one cell of the battery 105 having a cell voltage below a minimum cell voltage. Various cells of the battery 105 are not depicted in Figure la.

[0089] Figure lb depicts, in a schematic view, a second embodiment of an electronic pavement sign 101 according to the invention. Generally, the battery management system 107 comprises multiple components. In Figure la, the battery management system 107 is shown as a single block. Figure lb depicts an alternative, preferred, arrangement. The battery management system 107 comprises a battery module 127, communicatively connected with the battery 105 via a battery communication link 121. The battery management system 107 further comprises a charger module 129, communicatively connected with the battery module 127 via a management communication link 123. Also, the battery management system 107 comprises a charger 113, communicatively connected with the charger module 129 via a charger communication link 125. One or more of said links may be cables. The battery module 127 may be integrated with the battery 105. In case one or more cell voltages are too low, the battery module 127 may be configured to provide a zero voltage value to the charger module 129 via the management communication link. For example, if the series voltage of the cell is below 18 volt, the battery module 127 may send a zero voltage value to the charger module 129, such that the charger module 129 determines that the battery 105 is in the deep discharge state. The charger module 129 is configured to control the charger 113, via control signals sent via the charger communication link 125, to provide charging currents and / or voltages to restore the battery 105 from the deep discharge state. Generally, the battery module 127 may be configured to control the battery hardware and to provide a battery voltage value to the charger module 129. Based on the battery voltage value, the charger module 129 is configured to control the charger 113.

[0090] The battery management system 107 is configured to restore, if it is determined that the battery 105 is in a deep discharge state, the battery 105 from the deep discharge state to a normal state by applying in intervals a non-zero charging voltage and / or a non-zero charging current to the battery 105. In the description of Figure 5 such restoring is further detailed. The charging voltage and / or charging current are provided to the battery 105 using the cable 117. For example, at least one of the intervals of applying the non-zero charging voltage and / or a non-zero charging current to the battery 105 is at least one second. The battery management system 107 is configured to determine the battery voltage during the restoring from the deep discharge state, preferably in between the intervals. For example, the charger module 129 may determine that the battery 105 is still in the deep discharge state if a zero voltage value is received from the battery module 127. If the determined battery voltage is above the voltage threshold value, preferably at least 0.1 volt above the voltage threshold value, the battery management system 107 is configured to stop restoring the battery 105 from the deep discharge. For example, the charger module 129 may receive a voltage value above 18 V. Here, 18 volt may be the voltage threshold value. Also, if the restoring of the battery 105 does not function well, the battery management system 107 is configured to stop restoring the battery 105 from the deep discharge state after a predetermined number of intervals and / or after a predetermined amount of charging time. In the current embodiment, the predetermined number of intervals is 10 and the predetermined amount of charging time is 10 seconds. The electronic pavement sign 101 is configured to determine if the battery management system 107 charges the battery 105, and to prevent, if it is determined that the battery management system 107 does not charge the battery 105, a switching-on of the electronic display panel 103 if the battery voltage increases to above the voltage threshold value.

[0091] Figure 2 depicts, in a schematic view, a third embodiment of an electronic pavement sign 101. The embodiment depicted in Figure 2 extends the first embodiment with at least an additional ambient light sensor 201. Additional sensors, such as a temperature sensor and a humidity sensor may be present as well. The ambient light sensor 201 is connected to a display controller 203 via a sensor cable 205. The electronic pavement sign 101 is configured to control a brightness of the electronic display panel 103 based on an ambient light determined by the ambient light sensor 201. The electronic pavement sign 101 is configured to determine a stored energy and / or charge in the battery 105, for example by the battery management system 107. The battery management system 107 further determines an actual time, and determines a switching-off time associated with an expected time in which the electronic pavement sign 101 will be switched off. The actual time is determined using an internal clock. Based on said information, the electronic pavement sign 101 is configured to determine a remaining on-time as a difference between the actual time and the switching-off time. For example, in case a store closes at 18:00, the switching-off time may also be 18:00. In case the actual time is 15:00, the remaining on-time is 3 hours. The battery management system 107 is connected to the display controller 203 with a display controller cable 207. The electronic pavement sign is configured to control a brightness of the electronic display panel 103. Therefore, a power consumption of the electronic display panel 103 is controlled such that a consumed energy and / or charge by the electronic pavement sign 101 during the remaining on-time is less than or equal to the stored energy and / or charge in the battery 105. In this case, the brightness is controlled such that during 3 hours less power is consumed than is available in the battery. The relation between power consumption of an electronic display panel and its brightness is generally predetermined and provided by a manufacturer of the electronic display panel. For a given power consumption of an electronic display panel, the corresponding brightness may be determined using a look-up table or using a predetermined function. The switching-off time may be predetermined, for example by a predetermined closing time of a shop. Alternatively, the electronic pavement sign 101 is configured to estimate the switching-off time based on previous switching-off times. For example, if the electronic pavement sign has been switched of on average at 17:30 during the previous 14 days, the electronic pavement sign 101 may estimate that the coming switching-off time is also 17:30. In another example, if the latest moment that the electronic pavement sign has been switched off during the previous 14 day is 19:30, the electronic pavement sign may estimate that the switching-off time is 19:30.

[0092] Figure 3 depicts, in a schematic view, a fourth embodiment of an electronic pavement sign 101. The embodiment depicted in Figure 2 extends the first embodiment with at least an additional wireless communication module 301 connected 303 to the battery management system 107. The wireless communication module 301 is configured to transmit battery information to a remote computing system 305. Preferably, the battery information comprises information representative of the determined battery voltage. The battery management system 107 is configured to determine a health status of the battery 105 associated with operating parameters of the battery 105. The wireless communication module 301 is configured to further transmit information representative of the determined health status to a remote computing system 305, preferably if the determined health status indicates a decreased and / or low health of the battery 105. The electronic pavement sign 101 is configured to power-off the communication module 301 if the battery 105 is in and / or enters the deep discharge state. The computing system 305 is configured to wirelessly receive battery information from the electronic pavement sign 101. The computing system 305 is configured to determine, based on the battery information, whether the battery 105 is in the deep discharge state. The computing system may further determine that the battery 105 is in the deep discharge state if the determined battery voltage is decreasing over time and the last received determined battery voltage is less than 0.1 volt above the voltage threshold value. The computing system 305 further comprises a processor 307 which is configured to run a computer program. The computer program is configured to receive battery information representative of the determined battery voltage of an electronic pavement sign 101. The computer program also determines, based on the received battery information, whether the battery 105 is in the deep discharge state. The computer program further is configured to provide information on whether the battery 105 is in the deep discharge state to a user of the computer program. For example, the computer program initiates sending an electronic message, such as an email, sms or push-notification, to the user. Alternatively, the computer program may store said information on whether the battery 105 is in the deep discharge state into a database. The embodiment shown in Figure 3 further comprises wheels 309 for moving the electronic pavement sign 101 more easily. The electronic pavement sign may comprise additionally, or alternatively, other movement means as well, which are configured to aid a moving of the electronic pavement sign 101.

[0093] Figure 4 depicts a voltage curve 401 associated with a battery 105 comprised by an embodiment of an electronic pavement sign 101. During a discharging of the battery 105, the cell voltage drops. After a certain discharge level, indicated in Figure 4 with a DOD or Depth Of Discharge of 100% the voltage drops more rapidly. Typically, a DOD of 100% does not indicate that the battery 105 is fully discharged, but indicates a value to which a battery 105 may safely discharge, without entering a deep discharge state. The electronic pavement sign 101 according to the invention may discharge the battery 105 beyond a DOD of 100%. As a result, the electronic pavement sign 101 may operate for a longer time in comparison to an electronic pavement sign that would stop operating at a DOD of 100%. Note that the cut-off voltage is indicated in Figure 4 at a DOD of 100%, but in other embodiments the cut-off voltage of the battery may be set at a different DOD percentage, often at a lower percentage to increase life time of the battery. In particular, the electronic pavement sign 101 according to the invention enables operating the battery at a voltage below the cut-off voltage associated with a DOD of 100%, for example until the cell voltage reaches 0,5 volt. This increases the operation time per battery charge. As a result, the battery 105 is allowed to enter a deep discharge state, from which it may recover by the restoring operation of the battery management system.

[0094] Figure 5 illustrates charging intervals to restore the battery from a deep discharge state. The x-axis shows the time. The y-axis shows the battery voltage (solid line) and the battery current (dashed line), such as the battery charging current. Various periods are indicated with to, tl, ... , t9. A period lasts generally a couple of seconds. Note that on y = 0, the solid voltage line and the dashed current line overlap at some points.

[0095] In the period to - tl, the battery 105 is in the deep discharge state and the charger 113 is not charging the battery, for example because the charger 113 is not powered by the mains. The determined battery voltage is 0 V (volt) and the current is 0 A (ampere).

[0096] From tl onwards, the charger 113 is connected to the mains.

[0097] In the period tl - 12, the battery management system 107 determines that the battery 105 is in the deep discharge state since the battery voltage is below a voltage threshold value of 18 V. The battery management system 107 determines that the battery needs to be restored from the deep discharge state, despite the fact that a zero voltage is determined.

[0098] In the period t2 - 13, the battery management system 107 applies a non-zero charging voltage of 21 V. To protect the battery 105, the charging current is limited to 10 A. The limit of the charging current during the restoring of the battery 105 from the deep discharge state is lower than the limit of the charging current when the battery is in the normal state.

[0099] If the electronic pavement sign 101, in particularly the display, is turned off, the battery 105 consumes all power provided by the charger 113. If the display is turned on, or other components comprised by the electronic pavement sign 101, some part of the power provided by the charger 113 will be consumed by said components, and less power will be consumed by the battery 105.

[0100] In the period t3 - 14, after the first charging interval, the battery management system 107 is configured to determine whether the battery 105 is still in de deep discharge state. During such period after a charging interval, the charging current and voltage is zero. Also, the determined battery voltage is still zero. Preferably, the battery module 127 communicates a 0 V to the charger module 129. The battery management system, preferably the charger module, determines that a second charging interval is needed to restore the battery 105.

[0101] The period t4 - 15 is identical to the period t2 - 13, and the battery management system further continues to restore the battery 105 from the deep discharge state.

[0102] In the period t5 - 16, the battery management system determines that the battery is sufficiently recovered from the deep discharge state. Without applying a charging voltage, the battery voltage is now above 18 V. In case the electronic display panel is switched on, the battery current may become negative for a short time during the charging period as also some power from the battery is used to power the electronic display panel. From t6 on the battery is in the normal state, and a standard charging program may be applied. Depending on the battery voltage various charging phases may be identified. With each charging phase a particular charging current and / or voltage may be associated. The charger may now provide additional power to power the whole electronic pavement sign 101.

[0103] At t6, phase 1 of a normal current limited charge is started, until voltage reaches its end of phase voltage limit.

[0104] At t7, phase 2 of a normal current limited charge is started, until voltage reaches its end of phase voltage limit.

[0105] At t8, phase 3 of a normal current limited charge is started, until voltage reaches its end of phase voltage limit.

[0106] From t9, the battery 105 is sufficiently charged, and the charging current is zero A.

[0107] Figure 6 depicts a flow diagram of steps of an embodiment of a method for charging a battery 105 of an electronic pavement sign 101. The method comprises the following steps, which may be executed in any suitable order.

[0108] Step 601; determining a battery voltage of the battery 105.

[0109] Step 603; controlling, based on the determined battery voltage, a charging of the battery 105.

[0110] Step 605; determining that the battery 105 is in a deep discharge state if the battery voltage is below a voltage threshold value indicative of at least one cell of the battery 105 having a cell voltage below a minimum cell voltage.

[0111] Step 607; restoring, if it is determined that the battery 105 is in a deep discharge state, the battery 105 from the deep discharge state to a normal state by applying in intervals a non-zero charging voltage and / or a non-zero charging current to the battery 105.

[0112] Figure 7 depicts a flow diagram of steps of an embodiment of a method for adjusting a brightness of an electronic pavement sign 101. The method comprises the following steps, which may be executed in any suitable order.

[0113] Step 701; determining a stored energy and / or charge in the battery 105.

[0114] Step 703; determining an actual time.

[0115] Step 705; determining a switching-off time associated with an expected time in which the electronic pavement sign 101 will be switched off.

[0116] Step 707; determining a remaining on-time as a difference between the actual time and the switching-off time. Step 709; controlling a brightness of the electronic display panel 103 to control a power consumption of the electronic display panel 103 such that a consumed energy and / or charge by the electronic pavement sign 101 during the remaining on-time is less than or equal to the stored energy and / or charge in the battery 105.

[0117] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as basis for the claims and as representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting, but rather, to provide an understandable description of the invention.

[0118] The terms "a" or "an", as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least second or more. The terms including and / or having, as used herein, are defined as comprising (i.e., open language, not excluding other elements or steps). Any reference signs in the claims should not be construed as limiting the scope of the claims or the invention.

[0119] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that combination of these measures cannot be used to advantage.

Claims

Claims1. Electronic pavement sign, comprising:• an electronic display panel configured to present visual information to users;• a battery configured to power the electronic display panel;• a battery management system configured to: o determine a battery voltage of the battery; o control, based on the determined battery voltage, a charging of the battery; o determine that the battery is in a deep discharge state if the battery voltage is below a voltage threshold value indicative of at least one cell of the battery having a cell voltage below a minimum cell voltage; o restore, if it is determined that the battery is in a deep discharge state, the battery from the deep discharge state to a normal state by applying in intervals a non-zero charging voltage and / or a non-zero charging current to the battery.

2. Electronic pavement sign according to claim 1, wherein at least one of the intervals of applying the non-zero charging voltage and / or a non-zero charging current to the battery is at least one second.

3. Electronic pavement sign according to claim 1 or 2, wherein the battery management system is configured to:• determine the battery voltage during the restoring from the deep discharge state, preferably in between the intervals;• stop restoring the battery from the deep discharge state if the determined battery voltage is above the voltage threshold value, preferably at least 0.1 volt above the voltage threshold value; and• stop restoring the battery from the deep discharge state after a predetermined number of intervals and / or after a predetermined amount of charging time.

4. Electronic pavement sign according to claim 3, wherein the predetermined number of intervals is at least 10 and / or wherein the predetermined amount of charging time is 10 seconds.

5. Electronic pavement sign according to any of the preceding claims, comprising at least one sensor selected from a group comprising: an ambient light sensor, a temperature sensor and a humidity sensor.

6. Electronic pavement sign according to claim 5, comprising the ambient light sensor, wherein the electronic pavement sign is configured to control a brightness of the electronic display panel based on an ambient light determined by the ambient light sensor.

7. Electronic pavement sign according to any of the preceding claims, configured to:• determine a stored energy and / or charge in the battery;• determine an actual time;• determine a switching-off time associated with an expected time in which the electronic pavement sign will be switched off;• determine a remaining on-time as a difference between the actual time and the switching- off time;• control a brightness of the electronic display panel to control a power consumption of the electronic display panel such that a consumed energy and / or charge by the electronic pavement sign during the remaining on-time is less than or equal to the stored energy and / or charge in the battery.

8. Electronic pavement sign according to claim 7 , wherein the switching-off time is predetermined or wherein electronic pavement sign is configured to estimate the switching-off time based on previous switching-off times.

9. Electronic pavement sign according to any of the preceding claims, configured to:• determine if the battery management system charges the battery;• prevent, if it is determined that the battery management system does not charge the battery, a switching-on of the electronic display panel if the battery voltage increases to above the voltage threshold value.

10. Electronic pavement sign according to any of the preceding claims, further comprising a wireless communication module connected to the battery management system, wherein the wireless communication module is configured to transmit battery information to a remote computing system, wherein preferably the battery information comprises information representative of the determined battery voltage.

11. Electronic pavement sign according to any of the preceding claims, wherein the battery management system further is configured to determine a health status of the battery associated with operating parameters of the battery, and wherein the electronic pavement sign further comprises a wireless communication module connected to the battery management system, wherein the wireless communication module is configured to transmit information representative of the determined health status to a remote computing system, preferably if the determined health status indicates a decreased and / or low health of the battery.

12. Electronic pavement sign according to claim 10 or 11, configured to power-off the communication module if the battery is in and / or enters the deep discharge state.

13. Computing system, configured to wirelessly receive battery information from the electronic pavement sign according to any of claims 10 - 12, wherein the computing system is configured to determine, based on the battery information, whether the battery is in the deep discharge state.

14. Computing system according to claim 13, wherein the computing system is configured to determine that the battery is in the deep discharge state if the determined battery voltage is decreasing over time and the last received determined battery voltage is less than 0.1 volt above the voltage threshold value.

15. Computer program configured to:• receive battery information representative of the determined battery voltage of an electronic pavement sign according to any of claims 1 - 14;• determine, based on the received battery information, whether the battery is in the deep discharge state.

16. Method for charging a battery of an electronic pavement sign, comprising the steps of: a) determining a battery voltage of the battery; b) controlling, based on the determined battery voltage, a charging of the battery; c) determining that the battery is in a deep discharge state if the battery voltage is below a voltage threshold value indicative of at least one cell of the battery having a cell voltage below a minimum cell voltage; and d) restoring, if it is determined that the battery is in a deep discharge state, the battery from the deep discharge state to a normal state by applying in intervals a non-zero charging voltage and / or a non-zero charging current to the battery.

17. Method for adjusting a brightness of an electronic pavement sign, comprising the steps of: a) determining a stored energy and / or charge in the battery; b) determining an actual time; c) determining a switching-off time associated with an expected time in which the electronic pavement sign will be switched off; d) determining a remaining on-time as a difference between the actual time and the switching- off time;e) controlling a brightness of the electronic display panel to control a power consumption of the electronic display panel such that a consumed energy and / or charge by the electronic pavement sign during the remaining on-time is less than or equal to the stored energy and / or charge in the battery.

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