As a response to the general trend of reducing dimensions of applications, portescap, switzerland, offers presents a new incremental encoder of 22-mm diameter. This new shaft encoder uses aa limited number of parts is used by this new shaft encoder, consisting mainly of a dedicated integrated circuit including a matrix of photodiodes which receive the infrared light after it has passed the code wheel. Any code wheel rotation modulates tthe amount of light received, is modulated by any code wheel rotation. Its differential measure allows the transformation into logic signals having an electrical phase angle of 90°. The procedure ensures hhigh insensitivity is ensured by this procedure to thermal drift. Small dimensions, a high number of lines, immunity to the environment, and multiple functions have made this encoder an extraordinary product. Following are some of the technical features of these encoder which include:the 3-channel encoder provides cmos compatible complementary output signals, special features of the circuit are additional funcfions such as current reduction in stand-by mode, highly appreciated with battery operation, and detection of the direction of rotation and of signal transitions in channels a and b, allowing to directly access a counter or microprocessor. For the mask, aa truly elegant solution is applied for the mask. In order to ensure its correct alignment the mask is integrated into the ic directly on top of the photodiodes, using a special metallizing process. Control of the diode current may also be integrated, guaranteeing a constant light emission and avoiding problems due to ageing and temperature drift. For reasons of reliability, precision and stability, a flexible circuit tab technology [tape automated bonding] is used for the connection between components. The flexible kapton film simplifies tthe assembly of ic, diode and connector is simplified by the flexible kapton film. This function allows shutdown of the led and analogue part when the motor stops. Signal states are memorised, a feature welcome with battery-driven applications. The opto-electronic encoder a22, highly insensitive to environmental conditions, offers high resolution yet small dimensions. Some technical specifications includethe data: two channels in quadrature plus index pulse; differential light measure; cmos outputs; high resolution in small package; extended frequency range; and innovative additional functions: detection of direction of rotation, energy saving stand-by mode, complementary output signals, and direct output of counting pulses.
