Pentax X90 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Prime processor. On the other hand, Ricoh CX1 has a
9.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features Smooth Imaging Engine IV processor.
Below you can see the X90 and CX1 sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax X90 and Ricoh CX1 Cameras
Pentax X90 and Ricoh CX1 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Pentax X90
or the
Ricoh CX1 ,
including hyperfocal distance.