Outer Form
For the outer form of the eyeglass case, we wanted to choose a form that many people are familiar with and would intuitively know how to use. It also had to be large enough to hold all the hardware required for the "scanner" to work and sturdy enough to withstand constant handling.
The final design that we settled on was a flip-top eyeglass case (one that open from the side as opposed to a clam shell which opens from the middle). The bottom left and middle cases shown above are examples of flip-tops.
There are many ways a scanner can be revealed in an eyeglass case, we chose a symmetric configuration, to make the function of the scanner more obvious to the uninformed user. Asymmetry in the design may lead to confusion as to how the device should be held and what part of the device actually does the scanning. We decided to make the caps spring loaded to provide a surprise effect when the user pressed the opening mechanism. We could not rely on the user to pull the caps apart on their own will because that is not how normal cases are opened.
One of the concerns that we had was the size of the end caps on the eyeglass case. Large end caps (2 pictures below on the left) would make the case look less like an actual flip-top case, but give users larger side grips . Small end caps (2 pictures below on the right) would make the case look more realistic, but user would not be able to grip the eyeglass case as we had previously imagined it would be held.
We did a human use analysis to observe if the length of the end caps affected the way people held the scanner. Out of all the people surveyed (non-MIT, everyday people eating at the food court in the Galleria), most people chose to hold the glasses case sketch model with only hand (see video here). Therefore, we concluded that we should focus on making the dimensions of the case as close as possible to an actual case since users would not normally use the end caps as a place to grip.
Lighting
To provide the lighting effect for the scan, we had two possibilities that we chose to explore, ultra-bright LEDs and electroluminescent tape. Playing around with both, we saw that the LED's provided impressive lighting that shone out over a large range. Electroluminescent lights were also impressive, however, they lit up a surface only when it was in close range. We decided to go with the electroluminescent lighting for several reasons:
1. Very low profile (0.4 mm thick), which makes it easy to package in a small container
2. The close range of the light would suggest to the user that the scanner needs to be in close proximity to the document for it to actually scan the document. This eliminates the need for a proximity sensor. Remember, the RFID reader module needs to be within a certain range for it to register an RFID tag
3. The tape is flexible and can easily be cut to size. The interior of the case where the light will be mounted will have ribs to provide structural integrity. The electroluminescent lighting can be cut to fit around the structural ribs.
Placement
The lighting is used as a visual cue for the user to indicate that a scan is in progress. Placement of the electroluminescent tape affects the amount of light that is visible to the user. If the EL tape is positioned so that it is parallel to the document, the spread of light is very small and will be blocked from view from the user by the scanner itself. To alleviate this problem, the light with be offset from the center and placed on the radius of the scanner so that the user will be able to see the spread of light from underneath the scanner. This is the desired effect:
Clear lens
This image shows the clear plastic lenses that will be permanently set in the cutouts in the the bottom half of the main casing for the light to shine through. One side is curved to match the exterior form of the case. The other side is flat for the EL tap to lay on. Although the EL tape is very flexible about the minor axis, it is actually quite stiff about the major axis. Because of the curved nature of this piece, we may cast it out of clear liquid plastic (used by artists, craftsmen, and hobbyists for prototyping - http://www.smooth-on.com/proto.htm).
The EL tape will have to be cut into 3 strips to avoid the structural ribs in the main casing. To run three segments, wires need to be soldered to the back side of the tape where the electrical contacts are. Care needs to be taken to make sure there are no exposed electrical contacts since the light is converting DC power from the battery into 120 V AC.
