Display controller, screen transfer device, and screen transfer method

1. A screen transfer device comprising:

a main memory including a frame buffer;

a display controller configured to read frame data from the frame buffer, and generate a screen output image to be displayed on a display;

a dedicated memory disposed separately from the main memory; and

a system interconnect configured to interconnect the main memory, the display controller, and the dedicated memory with each other;

a path being provided for extracting the screen output image as a screen image for transfer to be transferred to another apparatus from the display controller, and writing back the screen image for transfer to the dedicated memory without the screen image for transfer passing through the system interconnect.

2. The screen transfer device according to claim 1 , further comprising

an encoder configured to compression-code the screen image for transfer;

a path being provided for the encoder to read the screen image for transfer from the dedicated memory without the screen image for transfer passing through the system interconnect, and write back the compression-coded screen image for transfer to the dedicated memory without the compression-coded screen image for transfer passing through the system interconnect.

3. The screen transfer device according to claim 2 , further comprising

an input-output section configured to output the compression-coded screen image for transfer to an outside;

a path being provided for the input-output section to read the compression-coded screen image for transfer from the dedicated memory without the compression-coded screen image for transfer passing through the system interconnect.

4. The screen transfer device according to claim 1 , wherein

the display controller reads frame data from a plurality of frame buffers, generates screen images in a plurality of paths, and synthesizes the screen images into a final screen output image, and

a path is provided for extracting each of the screen images generated in the respective paths and the synthesized final screen output image as the screen image for transfer from the display controller, and writing back the screen image for transfer to the dedicated memory without the screen image for transfer passing through the system interconnect.

5. The screen transfer device according to claim 1 , wherein the display controller has two channels of screen output, and generates two kinds of screen output images, one screen output image is output to a display panel connected to the display controller, and the other screen output image is extracted as the screen image for transfer.

6. The screen transfer device according to claim 5 , wherein the two kinds of screen output images are screen output images different from each other in resolution or refresh rate.

7. The screen transfer device according to claim 5 , wherein one of the two kinds of screen output images is an operating screen.

8. The screen transfer device according to claim 1 , wherein the dedicated memory is shared between screen transfer processing and downward compatible processing.

9. A screen transfer method for transferring a screen image in a device, the device including a main memory, a display controller, and a dedicated memory interconnected with each other by a system interconnect, the method comprising:

reading frame data from a frame buffer included in the main memory, and generating a screen output image to be displayed on a display by the display controller;

extracting the screen output image as a screen image for transfer to be transferred to another apparatus from the display controller, and writing back the screen image for transfer to the dedicated memory without the screen image for transfer passing through the system interconnect; and

compression-coding the screen image for transfer, the screen image for transfer being written back to the dedicated memory, and transferring the screen image for transfer to the other apparatus.