The original idea of ESP was to replace the matrix of obtuse pins in BoP with a matrix of LED lights connected and arranged on a PCB board. And this electronic version of “Bed of Pins” was planned to be a plane of LED lights of 364 units in a milky white box(Fig. 1). When one puts an object in contact with the bottom of the ESP, LED lights corresponding to the position will light up to reproduce the shape of the object.

To trigger the individual LED light to light up, a piezoresistor was planned to connecting between every single LED light and the positive pole of the battery pack. By constructing the elements in such a way, supposedly the LED light would light up when a certain amount of pressure is imposed to the corresponding piezoresistor to accomplish in creating the effect of BoP.

Changes made in the course of production

Due to the limited budget for the project, the the matrix, which was proposed to comprise 364 LED lights on a PCB board with area of 114.3 mm x 160 mm, is reduced to 48 LED lights on a PCB board sized 70 mm x 90 mm. And owing to the reason of budget constraint, the milky white cube is forfeited with great pity. In addition, 48 push switches are finally adopted rather than pizoresistors which cost approx. $20 each.

Technical Issues

In view of the above, the reason to the modifications done is limited budget. And there was literally no serious technical problems throughout the production process. Everything was well under control and attained a satisfactory quality.

In this project, basic physics of electricity is applied. ESP is composed of 48 identical units each of which consists of an LED light, a push switch and connecting wires(Fig. 2). In static situation, the LED light of the unit does not light up even though each unit is constantly connected to the the battery pack, because the push switch, during in its untriggered status, prevents the unit from forming a closed circuit in which electrons which carry electric energy can go through from negative pole to the positive pole of the circuit (while electric current flows in the opposite direction) – electric current only flows in closed electric circuit.

Further, each repeating unit of ESP is connected to each other in parallel to each other, so that the brightness of the LED light in each repeating unit, when lit up simultaneously, can be ensured to be the same. Each of the repeating unit bears the same amount of resistance, then the same amount of current passes through each of the repeating unit.

By V = IR, where V stands for Voltage, I for current and R for resistance

Thus, each of the units receives the same amount of Voltage, that is, in the case of ESP, 3V.

Possible Development of ESP

The working mechanism of ESP is, reduced to the very conceptual ground, a kind of switching on/off the lights in an interesting way. The present version of ESP is a bit small, to put this tiny little thing to its utmost, a huge bed of LED lights can be used, and instead of push switches, infrared sensors can be adopted. This gigantic bed of LED lights is to be installed horizontally so that people walking across it in its infrared side can be detected and the according LED lights would be switched on to form the shape of the passer-by(s).

for more photos: http://flickr.com/photos/cfran0421/tags/esp/

The idea of creating an electronic shape painter (ESP) is inspired by an old-fashioned toy that I do not even remember its name. The toy does not consist of any electronic parts, nor does it require any electricity to make it work. It is simply a “bed of pins” out of which player gain no pain but joy and fun. As its original name is forgotten, let’s call it “Bed of Pins” here, in abbreviation, BoP.

BoP is a miniature sized bed, which is roughly in the size of a human palm, with a square-shaped matrix of small pores on the surface. Through every of the small pores there loosely pins an obtuse pin, so that when one pushes the pins from the bottom of BoP with palm, the pushed pins will be raised, and the pattern of the palm will be form from the overhead view of the BoP.

In similar mechanism, the proposed ESP is to replace the matrix of obtuse pins in BoP with a matrix of LED lights connected and arranged on a PCB board. And this electronic version of “Bed of Pins” is to be a plane of LED lights in a milky white box. When one puts an object in contact with the bottom of the ESP, LED lights corresponding to the position will light up to reproduce the shape of the object.

The Methodology

The smallest working unit of ESP is the circuit consisting of a LED light and a piezoresistor, which triggers the on and off of the LED light, connecting to the power source. With thousands of these small working units, a whole “universe” of LED lights can be created. But in the case of ESP, only a matrix with certain size is to be built.

The matrix of LED lights are to be connected together in parallel, so that they will share the same amount of voltage in every electric cycle.