On-screen display unit
AssigneesRenesas Technology Corp., Renesas Lsi Design Corporation
InventorSeiji Matsumoto
Life of this patent
Estimating the term…
Abstract
An on-screen display unit includes OSD (on-screen display) RAMs each for storing data on one of OSD blocks to be subjected to OSD; a memory bus for transferring data to be stored to the OSD RAMs from a CPU; and an OSD local bus for transferring the data stored in the OSD RAMs to make the OSD. The OSD RAMs are supplied with the data to be stored through the control of switches alternately, and transfer the stored data to the OSD local bus 12 alternately. The on-screen display unit can cope with a high frequency OSD clock signal, and carry out the OSD normally.
Claims7
An on-screen display unit comprising:
- a CPU for generating data to be subjected to OSD (on-screen display);
- first and second OSD RAMs each for storing the data to be subjected to OSD in one of OSD blocks;
- a memory bus for transferring the data to be stored in said first and second OSD RAMs in synchronization with an operation clock signal of said CPU;
- an OSD local bus for transferring the data stored in said first and second OSD RAMs to be used for the OSD in synchronization with an OSD clock signal;
- a register to which said CPU sets a switching bit;
- a switch for connecting said first OSDRAM to said memory bus and said second OSDRAM to said OSD local bus in response to the setting of the switching bit;
- and
- OSD control circuit for generating an interrupt signal to said CPU at an end of OSD of the data stored in said second OSDRAM, wherein
- said CPU, receiving the interrupt signal, sets the switching bit of said register such that said switch connects said second OSDRAM to said memory bus and said first OSDRAM to said OSD local bus, and supplies said memory bus with subsequent data.
An on-screen display unit comprising:
- an OSD (on-screen display) RAM for storing data to be subjected to OSD;
- a memory bus for transferring data to be stored in said OSD RAM;
- a buffer for storing data read from said OSD RAM;
- an OSD local bus for transferring data in said buffer to be subjected to the OSD;
- and
- a buffer transfer control circuit for reading data necessary for the OSD on a horizontal scanning line from among the data stored in said OSD RAM and storing the data to said buffer, and for writing data from said memory bus to said OSD RAM during transfer of the data stored in said buffer to said OSD local bus.
Dependencies are inferred from the claim text.