Xiaomi 12s Ultra became the first mass and popular smartphone with an inch sensor, although not the first device with such a sensor on the market as a whole. True, the sensor there is not quite an inch.
Famous blogger JerryRigEverything after broke the new Xiaomi flagshipI decided to disassemble it in order to look at the same inch sensor of the main camera live.
As you can see, the physical dimensions of the sensor are very far from 1 inch, either diagonally or on one side. But there is no deception from Xiaomi or Sony. Although no one usually writes about this, in fact there is no secret about it, and the optical format of image sensors, although indicated in inches, is not actually measured directly in inches.
This situation was formed at the dawn of the appearance of digital image sensors, when they began to be used as a replacement for tubes in video cameras. And common inch tubes just had a rectangular photosensitive area with a diagonal of about 16 mm. And these are the dimensions of inch digital image sensors. That is, it is a sensor equivalent to a tube with a diameter of 1 inch. Because of this, a sensor that is physically about 1 inch diagonal will be listed as 1.5 inch.