Optical fingerprint sensor with folded light path

An optical fingerprint sensor module to be disposed under an opaque border of a display screen for detecting a fingerprint pattern of a finger placed adjacent a fingerprint sensing area of the display screen, the optical fingerprint sensor module comprising:

• a photodiode array having a surface;
• an optically transparent spacer disposed over the surface of the photodiode array;
• a first mirror configured to reflect signal light scattered or reflected off of the finger and transmitted through the display screen;
• a lens configured to receive and refract the signal light reflected by the first mirror, the lens having an optical axis that forms an angle with respect to a normal of the surface of the photodiode array that is between 45 degrees and 135 degrees;
• a member defining a pinhole disposed behind the lens, the pinhole configured to transmit the signal light refracted by the lens;
• a second mirror disposed behind the pinhole and above the optically transparent spacer, a normal of the second mirror being substantially perpendicular to the optical axis of the lens, the second mirror configured to reflect the signal light transmitted through the pinhole to be incident on the surface of the photodiode array at non-normal incidence;
• and
• electronic circuitries electrically coupled to the photodiode array, wherein the photodiode array is configured to convert the signal light incident thereon into electrical signals, and the electronic circuitries are configured to process the electrical signals to produce an image of a fingerprint pattern of the finger.

An electronic device comprising:

• a display screen including a fingerprint sensing area and an opaque border;
• a light source configured to provide illumination light directed toward a finger placed adjacent the fingerprint sensing area, a portion of the illumination light being scattered or reflected off of the finger, thereby generating signal light to be transmitted through the display screen;
• and
• an optical fingerprint sensor module positioned below the display screen under the opaque border, the optical fingerprint sensor module comprising:
• a photodiode array having a surface;
• an optically transparent spacer disposed over the surface of the photodiode array;
• a first mirror configured to reflect the signal light;
• a lens configured to receive and refract the signal light reflected by the first mirror, the lens having an optical axis that forms an angle with respect to a normal of the surface of the photodiode array that is between 45 degrees and 135 degrees;
• a member defining a pinhole disposed behind the lens, the pinhole configured to transmit the signal light refracted by the lens;
• a second mirror disposed behind the pinhole and above the optically transparent spacer, a normal of the second mirror being substantially perpendicular to the optical axis of the lens, the second mirror configured to reflect the signal light transmitted through the pinhole to be incident on the surface of the photodiode array at non-normal incidence;
• and
• electronic circuitries electrically coupled to the photodiode array, wherein the photodiode array is configured to convert the signal light incident thereon into electrical signals, and the electronic circuitries are configured to process the electrical signals to produce an image of a fingerprint pattern of the finger.