I recently bought two mini cameras from aliexpress, and the sensor is a bit unusual. It is more sensitive to infrared light than most CMOS sensors, so at day and incandesct scenes it looks purple, also, as you see in the image, when the camera looks at the sun it goes black with a color artifact around, which doesn't happen with most CMOS sensors. I doubt it is a CCD sensor, because the cameras where extremely cheap and CMOS sensors are massively produced. Maybe the camera have a cheaper sensor with a lack of filters or extra components to avoid the overexposure. Also the colors are very low saturated, almost white and black sometimes, maybe because the color filters are not too good and let too much wavelengths to get in the sensor.

All the camera driving, clock, time stamp, controls and encoding is handled by a single little chip in the board.

Here's an image exposing the camera to the sun.

Here's an image lit by a halogen bulb.


Both images where downscaled from the original 1280×960 to 640×480, probably the camera did the same thing but reverse. 

The pictures are encoding in a very compressed JPG, and the videos are encoded in MJPEG, the audio is PCM 8000Hz all on an AVI container, pretty common with those cameras.

It is unlikely anything else than CMOS, but with the IR blocking filter missing. The IR then excites the blue element.

It is unlikely anything else than CMOS, but with the IR blocking filter missing. The IR then excites the blue element.

The picture of the sun is missing, but when it looks the sun directly the sun becomes black with a little color artifact around maybe from the JPEG compression. I'll add the picture for a better look. Is there a filter missing that is not avoiding it?

Also the camera comes with an infrared lamp for night vision, maybe that's why they removed the filter.

The "black sun" means the sensor is really very likely CMOS.
It could have two reasons:
First it is an intentional feature, designed to help the operators to see against bright objects, like the sun or car headlights and so on. It is usually implemented on the pixel level, in the electronic around each pixel. It makes sure the saturation does not activate parasitic bipolars, causing the overload to "leak" to pixels around, blocking them too. Usually used with cameras designed for security systems.
Other cause could be the auxiliary pixel circuits not properly shielded. Usually a metal layer is made over the whole chip, with holes in it on top of the sensing diodes. This shield then usually means an extra metal layer in the semiconductor process, which is practically unusable for any interconnects (when it must be solid in order to do its light shielding job), maybe just ground connection. The overillumination then may cause photo currents in the circuits surrounding each pixel so intense, it causes the signal to flip to "dark".

Definitely these effects are never present in CCD, there the overloaded spot just "overflows" to surrounding pixels, or swipes the signal from the complete row, so causing horizontal lines across the whole frame, or from the overloaded spot to the picture edge.
 

I updated the sun picture.

The interesting thing is that if I point the camera to a 70W halogen, 250W SBMV or whaterver the black spot doesn't appear, only with the sun. Despite the sun goes black, all the image blooms too. The camera was kind of intented as surveillance, it have a mounting bracket, night vision, motion detection and a composite video output (which doesn't work), so a sun blackout feature might be added intentionally, but it doesn't work at all beacuse the image blooms.

Also, here's some media info BTW.
General
Complete name               : C:\Users\Alumno\Videos\Videos 2020\AVI 2020\81.AVI
Format                      : AVI
Format/Info                 : Audio Video Interleave
File size                   : 33.5 MiB
Duration                    : 26 s 233 ms
Overall bit rate            : 10.7 Mb/s

Video
ID                          : 0
Format                      : JPEG
Codec ID                    : MJPG
Duration                    : 26 s 233 ms
Bit rate                    : 13.9 Mb/s
Width                       : 1 280 pixels
Height                      : 960 pixels
Display aspect ratio        : 4:3
Frame rate                  : 30.000 FPS
Color space                 : YUV
Compression mode            : Lossy
Bits/(Pixel*Frame)          : 0.376
Stream size                 : 43.3 MiB

Audio
ID                          : 1
Format                      : PCM
Format settings             : Little / Signed
Codec ID                    : 1
Duration                    : 25 s 853 ms
Bit rate mode               : Constant
Bit rate                    : 128 kb/s
Channel(s)                  : 1 channel
Sampling rate               : 8 000 Hz
Bit depth                   : 16 bits
Stream size                 : 404 KiB (1%)
Alignment                   : Aligned on interleaves
Interleave, duration        : 194  ms (5.83 video frames)


And some image info.

General
Complete name               : C:\Users\Alumno\Pictures\Fotos 2020\PICT0010.JPG
Format                      : JPEG
File size                   : 54.0 KiB

Image
Format                      : JPEG
Width                       : 1 280 pixels
Height                      : 960 pixels
Color space                 : YUV
Chroma subsampling          : 4:2:2
Bit depth                   : 8 bits
Compression mode            : Lossy
Stream size                 : 54.0 KiB (100%)

I wonder why the infrared light exites the blue pixels.

I wonder why the infrared light exites the blue pixels.

Cameras use interference filters, so if there fits one wavelength of IR instead of two wavelengths of blue into the layer thickness or some grating distance, it reflects/passes through the same way.
Using 2'nd overtone thickness for the blue makes it sharper cut off on the border, but also passes the IR as the consequence.
That is the reason a dedicated IR blocking filter is needed, when you want to maintain good colors. But security use benefits more from the eventual IR illumination and does not need good colors that much, so the filtres are omitted.

The bright suppression feature is not aimed that much on the sun, but mainly incandescent car headlights (to make a car approaching the camera post visible,...). Dont forget the incandescents are nearly 10x brighter in IR than they are in visible, so HID may not be by far that bright. Of course, the sun is another level there...

The fact the image is flooded could be due to the optic being dirty or degraded over the years (if we are talking about some used equipment). And this dirt is, what essentially makes the security cameras reaching EOL - the scatter makes the image too bad to recognize/read anything useful there.
If it is on something "new" (from ebay,...), I would be questionning if it is really as new as promised or if it is really such bad quality. To be honest such sun swamping is not supposed to be that bad as it is on your picture.

I bought the cameras brand new in the box for very cheap, so I wasn't expecting much quality out of it. So in order to get decent pictures under the sun or incandescent I'll need an external IR filter. The automatic gain control can't reduce the brightness that much like with less cheaper cameras, and it easily overexposure under daylight scenes due to the IR light. Also, even if the picture output is 1280×960 the image looks like pretty much like analog video, with the common color artifact around detailed edges always present in analog video, and also because the image looks like upscaled from 720×480. That may be explained by that the camera have a composite video output (which doesn't work in both my cameras by some reason).