PURPOSE: To obtain a special effect waveform generator with a simple circuit constitution, which generates wipe key signals for polygon, star shape and heart shape not easily generated by conventional integration circuits and digital counter systems, by using an undermentioned system.
CONSTITUTION: A horizontal address generating circuit 11 is a counter which is cleared once at one horizontal period with a horizontal synchronizing signal and counted by one each at each horizontal clock signal. When the horizontal clock frequency is 14.3MHz, the count value is enough for 10-bit (1023) in binary number. A vertical address generating circuit 12 is a counter which is cleared once at two vertical period with a vertical synchronizing signal and summed by one at each horizontal synchronizing signal. A memory circuit 13 takes a count value from a horizontal and a vertical address generator as an address input signal, and in case of a circular wipe, the center of screen is taken as a peak potential, and a conical shape 10 as shown in the figure in which the potential is changed proportional to the distance from the picture center is stored, allowing to obtain the circular wipe key signal by comparing a fader control voltage with a special effect signal at a comparison circuit 14.
SUZUKI YASUO
SEKIGUCHI MASAO
KEZUKA EIJI
| JPS5341123A | 1978-04-14 | |||
| JPS55163981A | 1980-12-20 | |||
| JPS5375725A | 1978-07-05 |