The HP D3500 has a CCD sensor type which is better than the MOS sensor type found on most digital cameras that have been around for a comparable time to it. CCD sensors produce high quality, low-noise images but consume a lot more power than CMOS sensors. CCD is the most common image sensor type used in digital cameras.
This digital camera's sensor type (CCD) is in fact the best sensor type across all digital cameras of this age and type.
A MOS sensor type is the worst sensor type amongst comparable types of digital camera.