If the readings from the phototransistor are below a certain level, then the phototransistor/LED pair are flagged as bad.
Also, a method of making such a phototransistor, and a method of detecting light using such a phototransistor.
A signal from the phototransistor is sent to a triggering circuit (51, 89, 100, 102) by interrupting light transfer between the LED and the phototransistor.
The addressing transistor (16) comprises a phototransistor, and the data line (6) is used for external monitoring of the phototransistor.
The photo control circuit includes a phototransistor.
The photo transistor has a light sensitive region (112, 910) for controlling the transistor action of the photo transistor.
The dielectric layer is in contact with the photo transistor.
A photo transistor is used as the photodetector (M4).
The bias current path (12) is turned ON before photoreception start of the photo transistor (210) and is turned OFF when a predetermined time has elapsed after start of photoreception by the photo transistor (210).
Finger position sensing by a light emitting diode and photo transistor is also provided.
In this way a more efficient and flexible biasing of the phototransistor is possible.
In addition, it becomes possible to use the phototransistor as a TFT switch.
A phototransistor includes an emitter, a collector, and a base in lateral alignment.
A suitable light-detecting element (110, 110a, 110b) is a phototransistor, and a suitable light-emitting element (110, 110a, 110b) is a photodiode.
Preferably, the switching element is a phototransistor in consideration of the productivity of the magnetic disk device.
The sensor utilizes a phototransistor to measure light emitted by an infrared light emitting diode.
A bipolar phototransistor (200) generates a photocurrent (Ibi) in response to illumination.
A capacitor (16) couples the emitter of the phototransistor to ground.