High-density optical pickup for rotating media

An optical pickup apparatus for reading information on a rotating optical medium, comprising:

• a light source adapted to direct two beams of light onto adjacent locations on a track of said optical medium;
• first and second optical sensors positioned to detect reflection of said beams of light from said optical medium and to produce a leading electrical signal and a lagging electrical signal, respectively;
• said leading and lagging electrical signals being proportional to an amount of light detected within each beam;
• a delay circuit adapted to delay said leading electrical signal to at least partially coincide with said lagging electrical signal;
• and
• means for combining said delayed leading electrical signal with said lagging electrical signal to produce a combined electrical signal in response to the overlap
• between said delayed leading electrical signal with said lagging electrical signal.

An optical pickup apparatus for reading information on a rotating optical medium, comprising:

• means for optically reading adjacent optically encoded positions along a track of said rotating optical medium and generating a leading and lagging electrical signal in response thereto;
• means for delaying said leading electrical signal to at least partially coincide with said lagging electrical signal;
• and
• means for combining said delayed leading electrical signal with said lagging electrical signal to produce a combined electrical signal in response to the overlap
• between said delayed leading electrical signal with said lagging electrical signal.

An optical pickup apparatus for reading information located on rotating optical medium, comprising:

• a light source adapted to direct two beams of light onto adjacent locations on a track of said optical medium,
• a first and a second optical sensor positioned to detect a reflection of said beams of light from said optical medium and to produce a leading electrical signal and a lagging electrical signal, respectively;
• said leading and lagging electrical signals being proportional to an amount of light detected within each beam;
• a delay circuit adapted to delay said leading electrical signal to at least partially coincide with said lagging electrical signal;
• and
• a summing circuit adapted to combine said delayed leading electrical signal with said lagging electrical signal to produce a combined electrical signal in response to the overlap between said delayed leading electrical signal with said lagging electrical signal.

An optical pickup capable of reading data along at least one of a plurality of tracks located on a rotating information plane of an optical medium which provides an electrical modulation of an effective spot size of a read beam, comprising:

• means for sensing optical information on a track, said optical information sensing means capable of generating a first electrical signal and a temporally lagging
• second electrical signal in response to the data encoded on said track;
• a delay circuit which introduces a temporal delay into said first electrical signal so that it at least partially coincides with said second electrical signal;
• and
• a multiplier circuit which receives and combines said first and said second electrical signals to output a third electrical signal related to the coincidence between
• the delayed first electrical signal and said second electrical signal;
• whereby the effective spot size of the read beam may be varied in response to an amount of coincidence created as a result of the delay introduced into said first
• electrical signal.

An apparatus for reading information on an information plane of an optical medium, comprising:

• a first read beam forming a first spot on a track located on said optical medium;
• a second read beam forming a second spot on the track;
• wherein said second spot is located proximate said first spot;
• a first photodetector for receiving a reflected portion of said first spot resulting in a first electrical signal;
• a second photodetector for receiving a reflected portion of said second spot resulting in a second electrical signal, said first and said second electrical signals having a time delay therebetween based on a relative velocity and a distance between the first spot and the second spot with respect to the surface of the optical medium, the second being earlier in time than the first electrical signal;
• an adjustable time delay element coupled to an output of said second photodetector for delaying said second electrical signal by a predetermined value;
• and
• a coincidence handling element for merging said first electrical signal with said delayed second electrical signal according to a predetermined value to produce a third electrical signal corresponding to a third spot having an effective diameter less than the diameters of said first and second spots, said third spot diameter being varied by adjusting the time delay element.

A method of electronically adjusting the effective beam spot size of an optical pickup when reading data bits optically encoded within a track of an optical medium subject to rotational movement, comprising:

• impinging a first and second beam onto a selected track of said optical medium, wherein said first beam is nearby, and temporally precedes, said second beam;
• detecting the reflections of said first and said second beams from said optical medium;
• generating first and second electrical signals in response to the detected reflections of said first and said second beams;
• delaying said first electrical signal in relation to said second electrical signal;
• wherein the waveform represented in said first electrical signal and said second electrical signal in response to the reflection of an identical data bit along said track is brought into at least partial temporal coincidence;
• and
• combining said delayed first electrical signal with said second electrical signal, and
• outputting a third electrical signal therefrom having a waveform in response to the reflection of a single data bit whose effective spot size is determined by an amount of coincidence between the waveforms represented by said delayed first waveform and said second waveform as determined by an amount of delay introduced in said second electrical signal, and the distance between said first and second beam spots, and the speed of said medium.

An apparatus for reading information encoded on a surface of an optical medium comprising:

• (a) an optical pickup for generating a first read beam and a second read beam, said first read beam forming a first spot on a track and said second read beam forming a second spot on the track, wherein said second spot is proximate to said first spot, and said track is located on said surface of said optical medium;
• (b) a first photodetector for receiving a reflected portion of the first spot and resulting in a first electrical signal;
• (c) a second photodetector for receiving a reflected portion of the second spot resulting in a second electrical signal, the first and second electrical signals having a time delay therebetween based on a relative velocity and distance between the first spot and the second spot with respect to the surface of the optical medium, said second electrical signal being earlier in time than said first electrical signal;
• (d) a time delay element coupled to an output of said second photodetector for delaying said second electrical signal by a predetermined value,thereby resulting in a delayed second electrical signal, and
• (e) a multiplier that multiplies said first electrical signal by said delayed second electrical signal according to said predetermined value to produce a third electrical signal corresponding to a third spot having an effective diameter less than the diameters of said first and said second spots, the diameter of said third spot being variable by adjusting said time delay element.

A method for reading information encoded on a surface of an optical medium comprising:

• (a) impinging a first read beam forming a first spot on a track;
• (b) impinging a second read beam forming a second spot on the track, said second spot being proximate said first spot;
• (c) generating a first electrical signal associated with a reflected portion of said first spot;
• (d) generating a second electrical signal associated with a reflected portion of said second spot, said first and second electrical signals having a time delay therebetween based on a relative velocity and distance between said first spot and the second spot with respect to the surface of the optical medium, said second electrical signal being earlier in time than said first electrical signal;
• (e) delaying said second electrical signal by a predetermined value, thereby resulting in a delayed second electrical signal;
• and
• (f) multiplying said first electrical signal by said delayed second electrical signal to produce a third electrical signal corresponding to a third spot having an effective diameter less than the diameters of said first and said second spots, respectively.

A method for reading information on a rotating optical medium, comprising:

• reading adjacent optically encoded positions along a track on said rotating optical medium;
• generating a leading and a lagging electrical signal in response thereto;
• delaying said leading electrical signal to at least partially coincide with said lagging electrical signal;
• and
• combining said delayed leading electrical signal with said lagging electrical signal to produce a combined electrical signal in response to an overlap between said delayed leading electrical signal with said lagging electrical signal.