WO2011070217A1

WO2011070217A1 - Handheld apparatus with solar cell

Info

Publication number: WO2011070217A1
Application number: PCT/FI2009/050989
Authority: WO
Inventors: Erno LÄHTEENMÄKI
Original assignee: Nokia Corporation
Priority date: 2009-12-09
Filing date: 2009-12-09
Publication date: 2011-06-16

Abstract

In a non-limiting and exemplary embodiment, a method is provided for controlling a handheld electronic apparatus (10) with a solar cell module (220). An actuator (240) of the electronic device (10) is controlled to move at least one portion of the electronic device (10) in relation to movement of a light source to increase light energy absorption by the solar cell module (220).

Description

Handheld apparatus with solar cell

Field

The invention relates to handheld electronic apparatuses comprising a solar cell, and in particular to optimizing charging in such devices. Background

Solar cells are increasingly available for providing an auxiliary source of power for various handheld devices, such as mobile phones. Solar cell modules are available to be incorporated into handheld devices. For instance, a solar cell module may be included in a battery cover of a mobile phone.

The efficiency of solar cell charging is highly dependent on the orientation of a solar cell with respect to the sun. Thus, due to the sun's movement, the angle between the sun and the solar cell is not optimal for charging efficiency, due to the sun's movement even if the device was originally placed optimally. Brief description

Methods and apparatuses for optimizing charging of solar cells are now provided, characterized by what is stated in the independent claims. Some embodiments of the invention are described in the dependent claims.

According to an embodiment of the invention, an apparatus is pro- vided, the apparatus comprising: at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus at least to: control an actuator of a handheld electronic device to move at least one portion of the electronic device in relation to movement of a light source to increase light energy absorption by a solar cell module of the electronic device.

According to another embodiment, an apparatus is provided, the apparatus comprising means for controlling an actuator of a handheld electronic device to move at least one portion of the electronic device in relation to movement of a light source to increase light energy absorption by a solar cell module of the electronic device.

According to another embodiment, a method is provided for controlling a handheld electronic apparatus with a solar cell module. An actuator of the electronic device is controlled to move at least one portion of the electronic device in relation to movement of a light source to increase light energy absorption by the solar cell module.

The invention and various embodiments of the invention provide several advantages, which will become apparent from the detailed description below.

List of drawings

Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which

Figure 1 illustrates an electronic device with a solar cell module;

Figure 2 illustrates an apparatus according to an embodiment;

Figure 3 illustrates movement of the electronic device according to an embodiment;

Figure 4 illustrates an electronic device according to an embodi- ment;

Figure 5 illustrates an electronic device and a support according to an embodiment;

Figures 6 and 7 illustrate electronic devices according to some embodiments;

Figure 8 illustrates a method according to an embodiment; and

Figure 9 illustrates a method according to an embodiment.

Description of embodiments

The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiments), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

As illustrated in the simplified Figure 1 , a handheld electronic device 10 may comprise a solar cell module 20 on a cover portion of the device. For instance, the solar cell module 20 could be integrated in a battery cover of an electronic device or a first portion of an electronic device which is movable in relation to a second portion of the device. However, it will be appreciated that solar cells may be positioned in various outer portions of an electronic device. For instance, the solar cell module 20 may be formed by solar cells integrated in a display of the electronic device.

The efficiency of solar cell charging is highly dependent on the orientation of the solar cell with respect to a light source, such as the sun. The solar cells may be non-polarizing or polarizing. In the case of polarizing solar cells, even if the solar cell module 10 is positioned upwards to face the sun, the orientation of solar cell arrays with respect to the sun may have a significant influence on the efficiency of sunlight absorption.

Figure 2 illustrates a simplified embodiment of an apparatus accord- ing to an embodiment. The units of the apparatus may be part of the electronic device 10. The apparatus comprises a controller 210, a solar cell module or unit 220, a memory 230, and an actuator 240.

In accordance with an embodiment, an automatic light source tracking system for electronic devices is provided. The controller 210 may be ar- ranged to control the actuator 240 to move at least one portion of the electronic device 10 in relation to movement of a light source. In some embodiments this refers to moving of the entire electronic device 10, but it is possible to move only a portion of the electronic device 10 comprising the solar cell module 20. This facilitates achievement and/or maintenance of substantially an optimal di- rection of an absorbing surface of the solar cell module 220 with respect to the light source for providing as efficient solar cell based charging as possible. Thus, the electronic device 10 may be arranged to substantially track light source movement in order to increase solar energy absorption. No external devices are required to automatically control the electronic device 10 to be in an optimal direction with respect to the light source to enable increased solar energy absorption.

The controller 210 may be arranged to implement one or more algorithms providing an appropriate control output to the actuator 240 in accordance with the interface applied between the actuator 240 and the controller 210. For instance, the controller 210 may be arranged to control the actuator on and off, or provide more sophisticated instructions to the actuator 240, to achieve an optimal orientation of an absorbing surface of the solar cell module 220 with respect to the light source. Some further embodiments for arranging such algorithms are illustrated below in connection with Figures 8 and 9. The electronic device may also comprise a magnetometer 250 and/or a light sensor 260, the output of which may be used in some embodiments by the controller 210.

The apparatus may be implemented as an electronic digital com- puter, which may comprise memory, a processing unit with one or more processors, and a system clock. The processing unit may be adapted to implement the controller 210. The processing unit may be controlled by a sequence of program instructions transferred to the processing unit from the memory, such as the memory 230 illustrated in Figure 2.

An embodiment provides a computer program embodied on a computer-readable storage medium. Such computer program comprises one or more sequences of one or more instructions which, when executed by one or more processors of the apparatus, cause the apparatus to perform at least some of the actuator control related functions illustrated below in connection with Figures 3 to 9.

Such computer program code is stored in at least one memory of the electronic device, for instance the memory 230. The memory and the computer program code are configured, with at least one processor of the apparatus, to provide means for and cause the apparatus to perform at least some of the actuator control features illustrated below in connection with Figures 3 to 9 below. The computer program may be in source code form, object code form, or in some intermediate form. The actuator control features could be implemented as part of charging management and/or actuator control software, for instance.

At least some units of the apparatus, such as the controller 210, could be in a form of a chip unit or some other kind of hardware module for controlling a handheld electronic device. Such hardware module comprises an interface to connect the hardware module with the mobile communication device mechanically and/or functionally. The hardware module may form a part of the electronic device 10. Some examples of such a hardware module include a sub-assembly or an accessory device. Such apparatus providing the controller 210 could be a chipset or an integrated circuit suitable for use in a mobile station or a portable computer, for instance.

At least some of the features of the apparatus illustrated further be- low could be implemented by one or more integrated circuits, such as application-specific integrated circuits (ASIC). Other hardware embodiments are also feasible, such as a circuit built of separate logic components. A hybrid of these different implementations is also feasible.

Although the apparatus and the controller 210 are depicted as a single entity, different modules and memory may be implemented in one or more physical or logical entities. For instance, the controller 210 could comprise a specific functional module for carrying one or more of the steps in Figures 8 or 9. Further, the solar cell module 220 and the actuator 240 are illustrated as single entities, and it will be appreciated that there may be a separate controller or interface unit for the actuator 240 (e.g. a motor driving unit) and the solar cell module 220, to which the controller 210 may be connected. Further, there may be one or more sensors, such as a current sensor, connected to the output of solar cells of the solar cell module 220 and to the controller 210.

It should be appreciated that the apparatus, such as the electronic device 10 comprising the units of Figure 2, may comprise other structural and/or functional units, not discussed in more detail here. For instance, the electronic device 10 comprises one or more batteries which may be charged by current from the solar cell module 220, a charger, and battery, and a charging manager. Furthermore, a user interface of the electronic device 10 may be arranged to provide the user with access to control operations of the controller 210. For instance, the presently disclosed light source tracking functionality may be switched on and off on the basis of an input from the user.

In general, the various embodiments of the electronic device 10 may include, but are not limited to, cellular telephones, personal digital assistants (PDA), portable computers, imaging devices, gaming devices, media players, such as music or video storage and playback appliances, Internet appliances permitting Internet access and browsing, as well as other handheld electronic units or terminals that incorporate a solar cell module. The electronic device 10 may comprise any combination of these devices. In some embodiments, the electronic device 10 is a mobile communications device comprising one or more radio units and at least one antenna for wireless communications.

Let us now study some embodiments illustrating how the electronic device 10 may be arranged to enable tracking of light source movement. In some embodiments, the solar cell module 20 is positioned in the electronic de- vice 10 such that an absorbing surface of the solar cell module 20 is essentially in a vertical direction when the electronic device 10 is positioned in its rest position on a vertical surface. Thus, the electronic device can be positioned in the rest position on the support such that the solar cells face are upwards and the absorbing surface of the solar cell module 20 is substantially perpendicular to the sun at noon. For instance, reference is made to the devices illustrated in Figures 1 , 3, and 4.

In some embodiments, the electronic device 10 is controllable to rotate to substantially optimize the direction of the absorbing surface of the solar cell module 220 of the electronic device in view of charging efficiency. In Figure 3, the electronic device 10 may be lying on a surface, being illustrated as seen from the direction of a light source. The electronic device 10 is rotated to track the light source movement gradually from an initial position 300a to further positions 300b, 300c. Thus, the orientation of polarizing solar cells may be optimized. The rotation may be arranged in forward and/or reverse directions. A control algorithm of the controller 210 is arranged to define if forward or re- verse rotation is required. In a further embodiment, in the case of initial rotation to set the electronic device 10 in an optimal direction, the algorithm of the controller 210 may be arranged to define whether forward or reverse rotation enables the optimal direction to be achieved with the least movement.

In some embodiments, the actuator 240 is or comprises a vibration motor, for instance an uneven load vibration motor. By a suitably selected and located vibration motor and an appropriate mechanical structure design of the electronic device 10, the vibration motor can be controlled to move the electronic device to a predefined extent. For instance, the vibration motor may be controlled to rotate the device 10 by a predefined angle, such as an angle se- lected from a domain of 1 to 15 degrees. The vibration motor may cause rotation in forward and/or reverse directions. There are already vibration motors available enabling such controllable movement of a housing. One example of a vibration motor causing predefined movement of housing is disclosed in EP101 1249.

In an embodiment, as illustrated in Figure 4, at least one protrusion

400 may extend from a side of the electronic device 10 opposite to a side of the solar cell module 20. The protrusion may be ball-shaped, for instance. The protrusion is controllable to rotate the electronic device 10. However, it is to be noted that it is not necessary to have any protrusion extending from the elec- tronic device 10 to cause rotational movement of the electronic device 10, but an appropriate vibration motor inside the cover of the electronic device 10 may alternatively be arranged to cause the rotational movement.

Figure 5 illustrates another example, in which the electronic device 10 is placed on a support 500, such as a charging stand. The electronic device 10 and the support may be designed so that the actuator 240 in the electronic device 10 may rotate the support 500 together with the electronic device 10. The controller 240 may be arranged to control rotation of the electronic device 10 and the support 500 so that the solar cell module 20 is directed towards a light source.

Besides and/or in addition to by means of applying rotational movement around some axis of the electronic device 10, the electronic device 10 may be arranged to be moved by the internal actuator 240 in various other ways and directions. Thus, the moving of the at least one portion of the electronic device 10 into a more optimal position in relation to movement of a light source is to be understood broadly to cover changing of the orientation and/or center of gravity of the at least one portion of the electronic device.

In some embodiments, there is an angle between the absorbing surface of the solar cell module 20 and a vertical surface when the electronic device 10 is positioned in its rest position on the vertical surface. Thus, the ab- sorbing surface may have an angle of 0 to 90 degrees in a direction perpendicular with respect to the sun at noon, for instance. In some embodiments the angle may be varied.

With reference to Figure 6, in some embodiments the actuator 240 or a second actuator is configured to cause a support 600 to protrude from a cover of the apparatus to change the angle between the absorbing surface of the solar cell module 20 and the light source. Thus, it becomes possible to prolong the period during which the absorbing surface is perpendicular to the sun, and a more optimal angle for solar energy absorption can be automatically achieved after perpendicular alignment is no longer possible.

Figure 7 illustrates another embodiment, in which the electronic device comprises a first portion 700 and a second portion 702, and the second portion 702 is movable with respect to the first portion. The solar cell module 20 may be positioned in the movable portion 702, for instance on top of a ro- tatable or sliding cover.

In one embodiment, the actuator 240 is arranged to move the second portion 702 with respect to the first portion 700. The controller 210 may be arranged to control the actuator 240 to move the second portion 702 and thus the direction of the solar cell module 20. Thus, the angle between the absorbing surface of the solar cell module 20 and a light source may be automatically optimized to increase light energy absorption.

The electronic device 10 may comprise two or more actuators or actuating elements for moving the device. For instance, with reference to Figure 7, there may be one actuator to rotate the device in a horizontal direction and a second actuator, such as a motor, to change the position of the movable portion 702, i.e. move the second portion 702 in a vertical direction.

It will be appreciated that the above examples only represent few of a multitude of available implementation options, and the present features are not limited to some specific forms of the electronic device 10.

Let us now further study some embodiments for arranging algorithms for the automatic light source tracking functionality and control of the ac- tuator 240. The controller 210 may be arranged to detect a need for moving the electronic device 10 on the basis of inputs from one or more of the units 220, 230, 250, 260. With reference to the example of Figure 7, for instance, it will be appreciated that the features below also apply to embodiments in which only a portion of the electronic device 10 is moved.

In some embodiments, the controller 210 executes one or more predefined algorithms for detecting the need to move the electronic device 10 in order to be able to track sun movement. Such algorithm may be executed periodically, for instance.

In an embodiment, data indicative of required actuator control ac- tions associated with different times of day is predefined. In a simple example, if it is assumed that the electronic device is initially positioned substantially optimally towards the sun, the procedure may simply read a control action corresponding to the current time and control the actuator 240 accordingly. For instance, there could be a pattern causing the actuator to move the electronic device 10 by a predefined amount every 30 minutes.

In some embodiments, an output from the magnetometer 250 and/or other devices providing information on the current direction of the electronic device 10 is applied by the controller 210. Figure 8 illustrates an algorithm which may be applied by the controller 210 for initial movement of the electronic device 10 to an optimal direction and/or later for updating the direction of the electronic device to track sun movement. In step 810, an estimate of an optimal direction of (at least a portion of) the electronic device 10 is defined. For instance, the controller 210 may thus access a predefined table or data in some other form indicating optimal directions at different times of day. Alternatively, the controller 210 may calcu- late the estimate of the optimal direction. In one embodiment, the control is based on calculating an estimated direction of the sun on the basis of current time.

The current direction of the electronic device 10 is defined 820. For this purpose an output from the magnetometer 250 arranged as a digital com- pass may be applied. The estimate of an optimal direction is compared with the current direction of the electronic device 10 to determine if there is a need to change the direction of the electronic device 10. If, on the basis of a check 830, there is a need to change the direction, the controller 210 activates the actuator 240 to change the direction of the electronic device. The procedure checks 850 the current direction and compares 860 the current direction with the estimate of the optimal direction during the movement of the electronic device 10. If the optimal direction is achieved, the controller 210 controls 870 the actuator 240 to stop, and the procedure may return to step 810. Otherwise, the procedure returns to step 850.

By this embodiment it is not necessary to measure an output from the solar cell module 20, but the current solar cell absorption capability may be improved on the basis of a computational method applying the magnetometer output. It will be appreciated that a range of values may be defined in step 810. Thus, the procedure may define an optimal angle range in relation to the sun, and the electronic device 10 may be controlled to move to have the angle between the absorbing surface of the solar cell module 20 and the sun within the predefined angle range.

In some embodiments, current, voltage, or some other parameter indicating the status of the solar cell module 220 is applied by the controller 210 for determining if the electronic device 10 needs to be moved.

Figure 9 illustrates an embodiment in which a current level value dependent on a current light energy absorption level may be applied by the controller 210.

In step 910, the level of current from the solar cell module 220 is de- termined. This current level value may be defined also for charging management purposes in the electronic device 10. The current level is compared 920 with predetermined limits, which may be stored in the memory 230. In some embodiments, the limits may be automatically adapted. In a further embodiment, the limit setting is flexible and dynamically adapted in accordance with a current usage context. For instance, the limits may be set on the basis of current time and/or weather conditions. Thus, different limits may be applied in sunny and cloudy conditions. Those conditions may also change rapidly, for instance between checking whether the current position or angle of the electronic device 10 is optimum in relation to the sun.

If a need to move the electronic device 10 is detected in step 930, the actuator is controlled 840 to move the device, for instance by rotating the device.

It will be appreciated that instead of or in addition to using a current value, a voltage or another input can be used in the procedure of Figure 9. Fur- ther, also other criteria may be applied for determining if the device needs to be moved. For instance, the procedure may additionally use at least some of the features illustrated above in connection with Figure 8.

In some embodiments, an output from a light sensor 260 indicating a current quantity of light is used by the controller 210. In one embodiment the output from the light sensor 260 is applied as the criterion in the steps of Figure 9 instead of or in addition to the current level.

In an embodiment, the electronic device 10 is arranged to prevent the apparatus from being moved is response to the current light quantity level falling below a threshold value. Thus, a precondition of a minimum light level may be checked before execution of the light source tracking procedure, such as the algorithm illustrated in connection with Figure 8 or 9. This enables unnecessary and possibly disturbing movement to be avoided in low-light conditions or when the electronic device is in a pocket, for instance.

It is to be noted that the procedures of Figures 8 and 9 are simplified and various modifications could be prepared. For instance, step 810 could be carried out after step 820. In another different example, the actuator is controlled in step 840 to move the device 10 to a predetermined extent or for a predetermined time, after which the procedure returns to step 820.

In one embodiment, the procedure illustrated in connection with Fi- gure 9 is applied in a "trial and error" manner. The controller 210 may be arranged in step 920 to compare a current parameter value from the solar cell module 220 with at least one preceding parameter value before previous movement. For instance, if there is a substantial gap between the current level and the predefined limits, the controller 210 may control the electronic device 10 to turn five degrees. This may be done in both directions from the initial po- sition. The current levels are then checked in order to determine if a more optimal orientation is available for the electronic device 10. Thus, by trying small movements and comparing with previous current level(s), the direction of the electronic device may be optimized to achieve as high a charging current as possible.

It is also feasible to apply a combination of procedures illustrated above in connection with Figures 8 and 9. In an embodiment, the procedure illustrated in connection with Figure 8 is applied for initial movement of the electronic device from an arbitrary orientation to an optimal orientation with respect to the light source, and the procedure of Figure 9 of applying a current or light quantity level, for instance, is then applied for "fine-tuning" the orientation of the electronic device 10.

It is to be noted that the above features represent only some examples of available ways to implement the present features related to improving chargeability of an electronic device's battery by moving the electronic device. Various modifications can be made and some of the steps may be carried out in a different order.

It will be obvious to a person skilled in the art that as technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatuses, and computer program products. The combinations of claimed elements as stated in the claims can be changed in a number of different ways and still be within the scope of various embodiments of the invention.

Claims

1 . An apparatus comprising:

at least one processor, and

at least one memory including computer program code,

the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus at least to:

control an actuator of a handheld electronic device to move at least one portion of the electronic device in relation to movement of a light source to in- crease light energy absorption by a solar cell module of the electronic device.

2. The apparatus according to claim 1 , wherein the actuator is configured to rotate the electronic device.

3. The apparatus according to claim 2, wherein the actuator comprises a vibration motor embedded in the electronic device.

4. The apparatus according to any preceding claim, wherein the apparatus is configured to control the actuator or a second actuator to cause a support to protrude from a cover of the handheld electronic device to move the at least one portion of the electronic device.

5. The apparatus according to any preceding claim, wherein the apparatus is configured to control the actuator on the basis of a level of current from the solar cell module.

6. The apparatus according to any preceding claim, wherein the apparatus is configured to estimate the direction of the sun on the basis of current time,

the apparatus is configured to compare the estimated direction of the sun with the current direction of the at least one portion of the electronic device, and the apparatus is configured to control the actuator on the basis of the comparison.

7. The apparatus according to any preceding claim, wherein the apparatus encompasses the electronic device with the solar cell module and the actuator.

8. The apparatus according to claim 7, wherein the apparatus is a mobile communications device.

9. An apparatus comprising:

means for controlling an actuator of a handheld electronic device to move at least one portion of the electronic device in relation to movement of a light source to increase light energy absorption by a solar cell module of the elec- tronic device.

10. The apparatus according to claim 9, wherein the actuator is arranged to rotate the electronic device.

1 1 . The apparatus according to claim 10, wherein the actuator comprises a vibration motor embedded in the electronic device.

12. The apparatus according to any preceding claim 9 to 1 1 , wherein the apparatus is arranged to control the actuator or a second actuator to cause a support to protrude from a cover of the handheld electronic device to move the at least one portion of the electronic device.

13. The apparatus according to any preceding claim 9 to 12, wherein the means for controlling the actuator is arranged to control the actuator on the basis of a level of current from the solar cell module.

14. The apparatus according to any preceding claim 9 to 13, wherein the apparatus is arranged to estimate the direction of the sun on the basis of current time, the apparatus is arranged to compare the estimated direction of the sun with the current direction of the at least portion of the electronic device, and the means for controlling the actuator is arranged to control the actuator on the basis of the comparison.

15. The apparatus according to any preceding claim 9 to 14, wherein the apparatus encompasses the electronic device with the solar cell module and the actuator.

16. The apparatus according to claim 15, wherein the apparatus is a mobile communications device.

17. A method comprising:

controlling an actuator of a handheld electronic device to move at least one portion of the electronic device in relation to movement of a light source to increase light energy absorption by a solar cell module of the electronic device.

18. The method according to claim 17, wherein the electronic de- vice is rotatable by the actuator.

19. The method according to claim 17 or 18, wherein the actuator or a second actuator is controlled to cause a support to protrude from a cover of the handheld electronic device to move the at least one portion of the electronic device.

20. The method according to any preceding claim 17 to 19, wherein the actuator is controlled on the basis of a level of current from the solar cell module.

21 . The method according to any preceding claim 17 to 20, wherein the direction of the sun is determined on the basis of current time, the estimated direction of the sun and the current direction of the at least one portion of the electronic device are compared, and the actuator is controlled on the basis of the comparison.

22. A computer readable storage medium, comprising one or more sequences of one or more instructions which, when executed by one or more processors of an apparatus, cause an apparatus to perform at least some of the steps in claims 17 to 21 .