1. MATRIX: The design is to implement an N*N matrix and we are able to decide the color of each grid independently. When we scale down the matrix and improve the resolution, this will effectively produce a controllable clothes pattern display.
Why we design the MATRIX but not circle or other shapes? The idea to have a matrix is for flexible pattern control. By activating selected grids and adjusting them to set color, we are able to have nonemissive colorful display of circle, square, and even other random shapes and patterns. To make a prototype, we will make a matrix of 4*4 grids. With each grid of subject to 4 different colors, which means each grid is of 4 degrees of freedom, theoretically, the number of patterns available is N = 4^(4*4) = 4294967296
While the pattern is controllable, the display of fabric is not limited to any specific shape (square, circle, triangle, etc.) This module could be applied especially by fashion designers in their creative designs.
2. MATRIX CONTROL SYSTEM:
3cm*3cm Peltier Modules are applied currently to control the temperature of each grid, while the size of commercially available Peltier Module reaches as small as to 4mm*4mm, which will provide very good resolution.
There is two algorithms to implement the N*N MATRIX 1. N^^{2} output pins are connected directly to each grids. The color setting for each grid is directly passed to the temperature control modules (Peltier) under the grids. The complexity of the system is N^{^2} 2. The matrix is controlled by N parallel ROW inputs and N parallel COLUMN inputs, the complexity is therefore reduced to N. For example, to make adjustment to GRID_{ij}, ROW_{i} and COL_{j} is selected and GRID_{ij} is thus activated.
To simplify the complexity of the system, the 2^{nd} method is chosen.
3. SYSTEM IMPLEMENTATION: 1. A L6120 Dual Bridge Driver is used together with L298 Diode Bridge to control the direction of the current applied to each Peltier Module. The positive direction of current flow heats up the top face of the Peltier Module; the negative direction of current flow cool down the top face of the Peltier Module
2. 5V Relays are used to control the connection of ROWs and COLs. A microcontroller PIC16F877 is programmed to decide which COL and ROW to choose in order to activate the corresponding grids.
3. A switching algorithem is applied that each peltier module is assigned with a fixed time slot (switching frequency = fs). Since four peltier modules share the same PI controller, at one time, only 1 peltier module can be activated. By applying the switching scheme, the system sequentially check each peltier module. the swithcing frequency fs need to be much larger than the time constant of the peltier module.
