1 Single cell rechargeable battery power source for motorized shade FIELD OF THE INVENTION [0001] The present invention relates to a motorized window covering and motorized solar shading. BACKGROUND TO THE INVENTION [0002] Window covering and sun shading (shade as a short form in all contents hereafter) come in various forms including roller shades, roman shades, venetian blinds, curtains, louver systems and the like which function to control light and visibility through a window of a building or change casting of solar light to the building from various directions. A motorized shade has many advantages over a shade requiring manual operations to open and close. The present invention is developed for motorised shades, specifically systems that are designed to run off energy provided by rechargeable battery. Such a system may employ the use of photovoltaic modules to gather solar energy or other means to top-up or maintain an adequate energy level in the battery in order to operate the shades. The term single cell rechargeable battery is to be defined as: a rechargeable battery or parallel connected battery group such that the output voltage is determined by its fundamental electrochemistry polarisation between a single pair of cathode and anode. [0003] Motorised shades have many advantages compared to conventional manual types, such as better convenience, child safety and accessibility for the elderly/disabled. However, difficulty in accessing a suitable power supply has always been a main obstacle to widespread proliferation of motorised systems. With a cordless power source, the difficult and oftentimes costly task of rerouting existing line voltage wiring can be avoided. Breakthroughs have been made to address specific challenges with respect to the operating conditions and use cases of motorised shading, including: power output, temperature resistance, calendar life and cycle life. [0004] The conventional designs for rechargeable battery packs is inadequate for the intended application. This is due to the requirement for motorised shades to work maintenance-free for many years. Typical DC motors used for shading applications range from 12V to 24V, thus requiring a battery pack configuration that places 4 or more rechargeable cells in series. The problem is that it is very difficult to ensure that each cell within the battery pack performs identically for the entire lifecycle. Over time, and with repeated charging and discharging, the charge levels between cells become unbalanced, leading to a permanent and drastic loss of battery performance. An example of this phenomenon can be found in notebook computers - it is common to see a sharp decline in the performance of a notebook's battery pack after only a couple years of usage. As can be imagined, such a scenario would be unacceptable for motorised shades.
2 [0005] Single cell technology uses a single battery cell as the energy storage and power source for all motorization functions. This fundamentally eradicates all problems associated with multiple battery cells connected in series. Furthermore, the single cell technology to be described in the following embodiments is designed to deliver unprecedented voltage consistency across the battery charge range. This means a motor will not noticeably get slower as its battery drains. Another unique benefit is the ability to charge the battery using any off-the-shelf 5V smart phone charger or power bank. Such flexibility and convenience is made not only possible, but highly practical and cost-efficient using single cell technology. [0006] Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material formed part of the prior art base or the common general knowledge in the relevant art in Australia or any other country before the priority date of the claims herein. SUMMARY OF THE INVENTION [0007] The present invention consists of a single cell rechargeable battery as the electric energy storage and the power source to a motorized shade. Depending on the voltage level required to run the motor, the output of said rechargeable battery is boosted to a higher voltage level in order to power the motor via the motor control unit. A battery management circuit is connected to said rechargeable battery to prevent damage resulting from over-charging or over-discharging. [0008] The above arrangement ensures charging and discharging is only performed on a single battery cell, thus no unevenness would occur in the process. The battery life will be maximized to its natural life once over-charging and over discharging are also prevented. [0009] When the operating voltage of a motor is higher than the voltage level of a single cell battery, a boosting circuit is employed to generate the higher voltage level. This is to maintain the philosophy of using a single cell battery as the original power source. BRIEF DESCRIPTION OF THE DRAWINGS [0010] Further benefits and advantages of the present invention will become apparent from the following description of the preferred embodiments of the invention. The preferred embodiments should not be considered as limiting any of the statements in the previous section. The preferred embodiments will be described with reference to the following figures in which: [0011] Fig.1 shows a typical framework and the key elements of a single cell rechargeable battery power source in a motorized shade. The boosting circuit is necessary when the motor operating voltage is higher than the single cell battery 3 voltage. The battery provides power to the control signal receiving circuits when the system is in both standby and operating modes. It also provides power to the boosting circuit when the shade needs to be operated. When operation commands are sent to the control signal receiving circuits, it is further sent to a microcontroller in the motor control circuits that then translates the signals to execute these commands by energising the motor and output members to operate the shade system accordingly. [0012] FIG. 2 shows a schematic diagram of a typical motor control circuit in the subject invention. Practitioners in the art will recognize the electrical configuration of the system as essentially that of a conventional microcontroller-based control system, with control by means of momentary-contact switches and radio frequency (RF) signals, and powered by a rechargeable battery. These elements are well known in the art and used in a variety of commercially available products. Therefore, many aspects of FIG. 2 will be familiar to those knowledgeable in the art, and these aspects will be only briefly described. [0013] FIG. 3 shows a power management circuit which boosts a lower voltage level (single-cell battery voltage level) to the voltage level required to run the motor. DESCRIPTION OF PREFERRED EMBODIMENTS [0014] It is preferred that the rechargeable battery cell should be of a composition that has very high (1000+) cycle life, with the intention being that the battery should outlast the expected operating life of the overall motorized shade system. It is also preferred that the battery is of a chemistry that has a higher polarized voltage so as to reduce the difficulty and increase efficiency in boosting to a higher voltage level suitable for motor operation. In the preferred embodiment, input voltage to the charging circuit can range from 4.5V to 9V, whilst the voltage of the actual battery cell ranges from 3.5V in its charged state to 2.7V when the protection circuit kicks in. Output voltage of the boosting circuit is to be determined by the operating voltage of the motor. [0015] The components in all the circuits should have a characteristic of low electrical leakage. During standby mode, power consumption should be kept as low as possible. To achieve this, a microcontroller is implemented with firmware optimised for low power consumption. Key functionalities of the microcontroller include: manage receiving signals at a lower (battery level) voltage, signal encode/decode, command execution, system status observation and timing management. The firmware is preferably written in assembly language to minimise memory footprint, reduce microcontroller load and thus improve efficiency. This would enable the selection of lower specification microcontrollers, thereby reducing cost while at the same time ensuring fast response times. Practitioners in the art will be familiar with the basic features that a microcontroller needs to perform for such a control system.
4 [0016] In order to have adequate power to drive a shade system, the boosting circuit needs to be capable of sufficient current output (e.g. 2A). Consideration must be given to the efficiency of this circuit as its task is to convert the voltage level of the battery to the required level of the motor with minimal loss of energy. Since battery capacity needs to be been maximised for use in driving the system, this boosting circuit should not waste too much energy in voltage conversion. The inductor needs to be built with a high performance ferrite material and refined until the highest overall efficiency of boosting circuit is achieved. [0017] The present invention can be used in all kinds of motorised shading products including, but not limited to, roller blinds, roman blinds, venetian blinds, skylight shades, louver systems, ventilation systems as well as their associated control extrusions. Application of this invention can be extended to a broader range of DC powered products where a non-hardwired power source is deemed advantageous. This invention may take forms of integration with an actuator that includes a motor, signal receiving circuits and motor control circuits, or as an independent unit to be linked externally to an actuator.