Automatic focusing apparatus by means of phase discrimination

Claim 2

An improvement in the electric distance measuring apparatus in an automatic focusing apparatus equipped with an electric distance measuring means and arranged so as to control an objective lens by the electric signal generated from said means, said improvement residing in the arrangement comprising: a movable lens adapted to be controllable in the direction perpendicular to its optical axis, and a fixed lens having its optical axis in parallel with the optical axis of said movable lens; a vibrating plate element disposed on an image focusing plane common to said two lenses and provided with a first slit disposed in a position corresponding to said movable lens and a second slit disposed in a position corresponding to said fixed lens; a first lIght responsive means and a second light responsive means each being disposed closely behind said vibrating plate element and containing a photoelectric element adapted to convert the intensities of light varying with the contrasts of the image of the object to be photographed after passing through said first and second slits to electric signals directly expressing said image; a first amplifier and a second amplifier adapted to amplify the electric signals of said first and second light responsive means till said signals are saturated and to thereby covert the resultant signals to rectangular waves, respectively; and a phase discriminating means for discriminating the phase relationship of the pair of rectangular waves obtained from said two amplifiers.

Claim 3

An electric distance measuring apparatus according to claim 1, wherein said photoelectric elements of said first and second light responsive means are adhered closely to the rear side of said first and second slits, respectively, of said vibrating plate element.

Claim 4

An automatic focusing apparatus comprising a movable lens adapted to be controllable in the direction perpendicular to its optical axis, and a fixed lens having its optical axis in parallel with the optical axis of said movable lens; a vibrating plate element disposed on an image focusing plane common to said two lenses and provided with a first slit disposed in a position corresponding to said movable lens and a second slit disposed in a position corresponding to said fixed lens; a first light responsive means and a second light responsive means each being disposed closely behind said vibrating plate means and containing a photoelectric element adapted to convert the intensities of light varying with the contrasts of the image of the object to be photographed after passing through said first and second slits to electric signals directly expressing said image; a first amplifier and a second amplifier adapted to amplify the electric signals of said first and second light responsive means till said signals are saturated and to thereby convert the resultant signals to rectangular waves, respectively; a first shaping circuit adapted to produce a pulsating wave of a narrow breadth at the rising -up position of said rectangular wave representing the output of said second amplifier, and a second shaping circuit adapted to produce a pulsating wave of a narrow breadth at the depressed position of said rectangular wave; a vibration pick up means for converting the vibrations of said vibrating plate element to electric rectangular pulsating waves; a phase inverter for inverting the phase of said rectangular pulsating waves representing the output of said vibration pick up means; a first gate circuit using, as its input signals, the outputs of said first amplifier, said first shaping circuit and said vibration pick up means; a first subsidiary gate circuit using, as its input signals, the outputs of said first amplifier, said second shaping circuit and said phase inverter; a second gate circuit using, as its input signals, the outputs of said first amplifier, said first shaping circuit and said phase inverter; a second subsidiary gate circuit using, as its input signals, the outputs of said first amplifier, said second shaping circuit and said vibration pick up means; a first switching circuit for cutting off and passing a positive current by being energized by the outputs of said first gate circuit and said first subsidiary gate circuit; a second switching circuit for cutting off and passing a negative current by being energized by the outputs of said second gate circuit and said second subsidiary gate circuit; a power supply means; a servomotor connected to said first and second switching circuits and adapted for effecting the movement of said movable lens and an objective lens matched therewith; and there being provided an arrangement that the positions of said movable lens and said objective Lens are adjusted by said servomotor so that the phases of a pair of rectangular waves representing the outputs of said first and second amplifiers will agree to each other.

Claim 5

An automatic focusing apparatus comprising a movable lens adapted to be controllable in the direction perpendicular to its optical axis, and a fixed lens having its optical axis in parallel with the optical axis of said movable lens; a vibrating plate element disposed on an image focusing plane common to said two lenses and provided with a first slit disposed in a position corresponding to said movable lens and a second slit disposed in a position corresponding to said fixed lens; a first light responsive means and a second light responsive means each being disposed closely behind said vibrating plate means and containing a photoelectric element adapted to convert the intensities of light varying with the contrasts of the image of the object to be photographed after passing through said first and second slits to electric signals directly expressing said image; a first amplifier and a second amplifier adapted to amplify the electric signals of said first and second light responsive means till said signals are saturated and to thereby convert the resultant signals to rectangular waves, respectively; a first shaping circuit adapted to produce a pulsating wave of a narrow breadth at the rising -up position of said rectangular wave representing the output of said second amplifier, and a second shaping circuit adapted to produce a pulsating wave of a narrow breadth at the depressed position of said rectangular wave; a vibration pick up means for converting the vibrations of said vibrating plate element to electric rectangular pulsating waves; a phase inverter for inverting the phase of said rectangular pulsating waves representing the output of said vibration pick up means; a first gate circuit using, as its input signals, the outputs of said first amplifier, said first shaping circuit and said vibration pick up means; a first subsidiary gate circuit using, as its input signals, the outputs of said first amplifier, said second shaping circuit and said phase inverter; a second gate circuit using, as its input signals, the outputs of said first amplifier, said first shaping circuit and said phase inverter; a second subsidiary gate circuit using, as its input signals, the outputs of said first amplifier, said second shaping circuit and said vibration pick up means; a first switching circuit for cutting off and passing a positive current by being energized by the outputs of said first gate circuit and said first subsidiary gate circuit; a second switching circuit for cutting off and passing a negative current by being energized by the outputs of said second gate circuit and said second subsidiary gate circuit; a power supply means; a servomotor connected to said first and second switching circuits and adapted for effecting the movement of said movable lens and an objective lens matched therewith; and there being provided an arrangement that the positions of said movable lens and said objective Lens are adjusted by said servomotor so that the phases of a pair of rectangular waves representing the outputs of said first and second amplifiers will agree to each other.

Claim 6

An automatic focusing apparatus according to claim 3, wherein said first and second gate circuits are each comprised of an ''''AND'''' circuit and said first and second subsidiary gate circuits are each comprised of a ''''NAND'''' circuit.