Solid state image pickup device and signal reading method thereof

An image pickup apparatus comprising:

• a plurality of pixels arranged two-dimensionally in a horizontal direction and a vertical direction;
• a plurality of vertical output lines each of which is provided in common for every plurality of pixels arranged in the vertical direction;
• a plurality of horizontal output lines connected to said plurality of vertical output lines through a plurality of switches, for outputting sequentially signals from said plurality of vertical output lines, wherein said plurality of horizontal output lines are arranged so as to face each other with the pixels being disposed therebetween;
• and
• a scanning circuit, arranged to read out signals to said plurality of vertical output lines for every plurality of pixels arranged in the horizontal direction,
• wherein said image pickup apparatus has a first drive mode so that signals from first pixels arranged in the horizontal direction are read out to said plurality of horizontal output lines by turning on first switches of said plurality of switches, before signals of second pixels arranged in the horizontal direction are read out to said plurality of vertical output lines, and has a second drive mode so that second switches of said plurality of switches, the number of which is less than that of the first switches, are turned on and a lesser number of the horizontal output lines are used than in the first drive mode, thereby reading out signals from the pixels arranged in the horizontal direction, the number of the pixels being less than that of the pixels read out in the first drive mode.