Oh, well. I just did a stupid thing. I tried to convert the VGA signal to HDMI directly by using two adapters: VGA to DVI and DVI to HDMI.
There is no signal. Why?
VGA is analog signal; DVI has both analog and digital signal; HDMI only has digital signal. So, the two adapters filter out all the signal. Oops, nice try!
Nowadays, all the fancy electronic device has HDMI input or output. But, my old laptop still only have the VGA port - looks like I have to buy a VGA/SVGA cable now ...
Here are several images for these port.
(please note the connector above doesn't have the analog pins)