Final protoype

After a meeting we had, the final prototype was discussed and its features were decided. The following diagram is the outer design of the pen and the hardware configuration of its components.

As you can see from the diagram, the final prototype blends the features found in the previous prototypes. Its main features are:

1. A total height of 15cm. This size was decided to be the perfect size for children's hands to hold. It's not too small and not too large.
   
2. Near the end of the tip, the thickness of the pen is 1cm and covered with non-slippery surface. This makes it ideal to children's hands. It's also not too thick for children to hold and makes transition to ordinary pens and pencils easier.
3. A ballpoint sensor was decided to be used as the tracking mechanism. It was preferred over gyroscopes, because of its accuracy.
   
4. The thickness of the pen increases after the "grip" area ends. This is essential since room must be made for the hardware.
5. The top part of the pen will resemble the one found in the last prototype. It will accommodate an LCD screen and it will slightly bend inwards. This will help the user see what's actually going on on the screen without much effort. The back of the LCD will also be reinforced so that it can withstand brutal misuse.
   
6. The speaker and microphone will be just below the screen itself.
7. The button is placed just above the LCD. This makes unwanted presses limited.
8. Just above the non-slippery surface, some metal strips will provide connectivity with the included sync station. They will allow the pen to recharge from the sync station and also also communicate with the PC via USB connectivity.
9. The syncstation will be simple in design(cone) and will feature a hole so that the pen can be placed into the syncstation.No external power will be needed. All the power needed will be taken from the USB port.
10. Two LEDs on the syncstation will indicate charging and sync signals.
11. The weight of the pen must be no more than 85 g.
12. The tip of the pen can be unscrewed just above the base of the cone to refill the pen's ink container.
    

As you can see from the hardware design, the battery is placed just above the ink cartridge. This is necessary since the battery itself is the heaviest part of the pen and must be placed as low as possible so that the centre of gravity is low. This will help in stability when holding the pen.

The WiFi/Bluetooth functionality was decided not to be included. It wouldn't justify the extra cost as the synchronization with the PC is not the main feature of the pen. This can easily be compensated with USB connectivity and the extra battery life that would be saved if they are not included. The WiFi and Bluetooth modules would also add to the hardware complexity and add extra weight to the final product.

The screen will work in the same way as described in the last prototype. The way it interacts with the user is clear, precise and well illustrated for a child to follow. So we didn't have to redesign the interface for that. The screen however was slightly reduced so that it didn't seem out of place.

The sync station was chosen so as to free some space on the pen from having to include a USBplug. The pen will interact with the sync station via some metal contact points placed on the pen. When the pen is placed on the sync station, the metal points of the pen will come in conduct with the corresponding points found on the sync station. The sync station will be connected with the PC via a USB cable. When connected, the pen's software can be updated by running special software written for this purpose on the PC. The software can update the pen's dictionary as well as add new features to the pen's software. The pen can also switch to advanced mode from the PC software.