Optical pick-up head unit and information record and playback equipment using the optical pick-up head unit

An optical pick-up head unit comprising:

• a light source to radiate a beam;
• a focusing optical system that receives the beam radiated from the light source and converge the beam at a microspot on an optical recording medium;
• and
• a photodetector that receives the beam irradiated on the optical recording medium and outputs an electric signal corresponding to the quantity of the received light, wherein
• the photodetector comprises receiving parts for outputting signals used to generate a focus error signal, I-V converting parts to receive current signals outputted from the receiving parts and to convert the current signals into voltage signals, and a signal generating part, wherein
• the signal generating part generates first signals that change in the positive direction and second signals that changes in the negative direction when light enters the receiving part, and the ratio of the first signals to the second signals is substantially 1:1.

An optical pick-up head unit comprising:

• a light source to radiate a beam;
• a focusing optical system that receives the beam radiated from the light source and converges the beam at a microspot on an optical recording medium;
• and
• a photodetector that receives the beam irradiated on the optical recording medium and outputs an electric signal corresponding to the quantity of the received light, wherein
• the photodetector comprises receiving parts, I-V converting parts that receive current signals outputted from the receiving parts and convert the current signals into voltage signals, and a signal generating part that generates a first signal to change in the positive direction and a second signal to change in the negative direction when light enters the receiving part, and a delay correcting part to correct relative delay time between the first signal and the second signal.