Purse Light
This project was a result of hard work by a group of people for “New Product Development” class competition at Georgia Institute of Technology, School of Management in Spring of 2008.
Purse illumination idea has been around for quite a while. As we found during our patent search - the oldest relevant patent was dated 1946. However, none of designs were ever adopted for mainstream markets. Our goal was to create a prototype, that could be productised later incorporating state of the art technologies. Such technologies could be represented by miniature light sources, conductive fabrics and threads, lightweight rechargeable power sources, and etc.
First of all, we identified an existing customer need by searching and participating in internet forums related to fashion. Surprisingly, our idea generated a substantial amount of interest from users of the forums.
During our patent search we understood that it would be easier to distinguish our product from other existing ones by using contemporary technologies in our design. Therefore, conductive threads use was a main focus of our project as this feature would make our product stand out due to presence of illumination seamless to the design of a bag. That in its turn would make the potential customer choose it over others
Conductive Thread
In order to identify the customer needs, we offered an online survey using resources provided by our school (however, there are tons of other similar tools available online). We received total of 214 responses. The distinction in preferences between male and female responders was apparent with, as was expected, higher level of interest from the young female responders.
Based on the results of the survey we identified our core need to be “illumination” and important features to be “aesthetics, durability, versatility, long battery life, lightness, compactness, automatic engagement”.
During the concept selection stage we considered a vast variety of light sources, power supplies, wiring options, switches. By using a generation matrix with weighted criteria and aesthetics considerations we were able to narrow down the pool of concepts to a few. These few underwent testing.
The illumination performance was assessed for different light arrangements inside a prototype purse (purchased from a local retail store).
Prototyping Purse
Hard-wired high intensity LEDs were placed on the bag’s interior with a double sided tape using different arrangements (considered quantities and locations) and the performance of each was assessed.
Light Arrangement
During the durability testing we tested how conductive threads performed during deformation/impact, exposure to fluids, heat. These tests revealed a need for use of a special sewing technique - combination of a conductive thread and a normal thread. During this sewing process the conductive thread stays to one side of the fabric that makes it invisible or non-intrusive to the interior design of a bag and, most importantly, prevents the conductive threads from forming a short in the electric circuit.
Wet Testing
Based on the selected light intensity we estimated the battery life time, previously, choosing two AAA batteries as a power source (~16 weeks of use).
Based on the knowledge acquired during previous stages we build a prototype with the following characteristics.
Prototype
The best balance between light intensity and amount of LEDs was established at 6 LEDs located by 3 on each side of the bag diagonally (two diagonals crossing when viewed from the side).
Double sewing technique to isolate conductive threads from bag compartment and prevent electric circuit shorts. (view at the reverse side of the interior fabric)
LED mounting
- LED’s and resistor are strapped under conductive thread
- Flexibility, look, and texture of inner lining is not altered
Lights and Fabric
- Low weight and size of illumination system
An automatic switch, allowing light to come on every time the bag was opened, was incorporated in our prototype by placing a magnetic switch inside the bag’s existing features.
Automatic On/Off Switch
Furthermore, a manual switch allowing to disable the illumination was placed together with the battery holder in the side compartment of the bag.
Manual Switch
Finally, a fully working prototype.
Cost Estimate
| Cost Item | Cost Estimate |
|---|---|
| Components (LED’s, thread, resistors, switches, etc.) | $3.00 |
| 3 AAA batteries ($0.26 each) | $0.78 |
| Additional fabric, seams | $0.09 |
| Labor (15min work, $0.49 hourly rate in PR China) | $0.12 |
| Total | $3.99 |
Based on this analysis we concluded that additional cost will prevent entering low price segment ($10-20), but is negligible for medium and higher priced bags ($100-5000)
Future Improvements and Steps
- Plastic caps/or custom LEDS to further incorporate the lights in the bag design
- Addition of light sensor to circuit -> lights go on only in darkness
- Addition of timer to circuit -> lights turned off after specific time interval
- Use of different LED arrangements
- Evaluation of different concepts by focus groups
by Bhavneet Binder, Sonia Agrawal, Alexander Epple, Szabolcs Palinko, Michael Parnell, Sergey Tereshko
Tags: class project, illumination, led, purse
