Digital convergence correction device

摘要

The digital convergence correction device is used for a projection-type television receiver having a Braun tube with an aspherical surface fluorescent screen and a projection lens system with an aspherical surface plastic lens attached to the display screen of th Braun tube. In the digital convergence correction device, a digital memory stores digital correction data corresponding to correction values at the convergence adjustment points on the display screen that is divided in the horizontal and vertical directions. A multiplexer reads the digital correction data out of the digital memory, and implements the time division multiplexing for the data. A D/A converter receives the multiplexed data from the multiplexer, and converts it into an analog signal. The device is provided with sample-holding circuits for making coincident timing for the outputs of the time division multiplexing process, so that no phase shift arises at the time division process and multi-channel time division process is made possible. Among numbers of time divisions, an optimal one can be chosen to meet the system requirement. Consequently, the number of D/A converters is reduced thereby to down-cost the digital convergence correction device. The convergence correction device operates in accordance with the correction signals held in the respective sample-holding circuits.