Autofocus cine camera having automatic variable speed focusing

Claim 2

In an autofocusing camera of the type having, an image plane, an adjustable focus lens mounted for displacement over a given operational range where it serves to focus images of subjects positioned within a range of subject distances at said image plane, an ultrasonic rangefinder for deriving a subject distance signal representative of the distance to a particular subject within said range of subject distances, the improvement comprising: energizable drive means responsive to said subject distance signal for displacing said lens at one rate in a particular direction if the magnitude of lens displacement necessary to focus an image of said particular subject at said image plane is greater than one-eighth of the entire focusing range of said adjustable focus lens and at another rate in said same particular direction if said necessary lens displacement magnitude is equal to or less than said one-eighth of the entire focusing range of said adjustable focus lens.

Claim 3

The apparatus of claim 1, wherein said lens is displaced at a greater rate of speed to a desired focus position if said magnitude of necessary lens displacement is greater than said predetermined magnitude than it is displaced when said magnitude of necessary displacement is equal to or less than said predetermined magnitude.

Claim 4

The apparatus of claim 2, wherein said greater rate of speed is twice that of the other rate of speed.

Claim 5

The apparatus of claim 1, wherein said energizable drive means includes a reversible variable speed motor for displacing said lens to a desired focus position.

Claim 6

The apparatus of claim 4, wherein said reversible variable speed motor is of the direct current type.

Claim 7

The apparatus of claim 5, wherein said drive means includes a variable voltage power supply whose output voltage is variable between two voltage levels, the particular voltage level being dependent upon the magnitude of lens displacement necessary to focus an image of said particular subject at said image plane.

Claim 8

The apparatus of claim 6, wherein said drive means includes a bridge-type switching circuit for connecting said variable voltage power supply to said variable speed reversible motor.

Claim 9

In an autofocusing camera of the type having, an image plane, an adjustable focus lens mounted for displacement over a given operational range where it serves to focus images of subjects positioned within a range of subject distances at said image plane, an ultrasonic rangefinder for deriving a subject distance signal representative of the distance to a particular subject within said range of subject distances, means responsive to said subject distance signal for deriving a lens movement signal representative of the lens displacement necessary to displace said lens from a present position to one selected in accordance with said subject distance signal so as to focus an image of said particular subject at said image plane, the improvement comprising: energizable drive means for displacing said lens an amount in correspondence with said lens movement signal at one rate in a particular direction while the magnitude of said lens movement signal is less than or equal to a signal corresponding to one-eighth of the entire focusing range of said adjustable focus lens and at another rate in said same particular direction while said magnitude of said lens movement signal is greater than said predetermined magnitude.

Claim 10

In an autofocusing camera of the type having, an image plane, an adjustable focus lens mounted for displacement over a given operational range where it serves to focus images of subjects positioned within a range of subject distances at said image plane, an ultrasonic rangefinder for deriving a subject distance signal representative of the distance to a particular subject within said range of subject distances, means responsive to said subject distance signal for deriving a lens movement signal representative of the lens displacement necessary to displace said lens from a present position to one selected in accordance with said subject distance signal so as to focus an image of said particular subject at said image plane, the improvement comprising: energizable drive means for displacing said lens an amount in correspondence with said lens movement signal at one rate in a particular direction while the magnitude of said lens movement signal is less than or equal to a signal corresponding to one-eighth of the entire focusing range of said adjustable focus lens and at another rate in said same particular direction while said magnitude of said lens movement signal is greater than said predetermined magnitude.

Claim 11

The apparatus of claim 8, wherein said lens is displaced to a focus position at a greater rate of speed when the magnitude of said lens movement signal is greater than said predetermined magnitude than it is displaced when said lens movement signal is equal to or less than said predetermined magnitude.

Claim 12

The apparatus of claim 9, wherein said greater rate of speed is twice that of the other rate of speed.

Claim 13

The apparatus of claim 8, wherein said energizable drive means includes a reversible variable speed motor for displacing said lens to a desired focus position.

Claim 14

The apparatus of claim 11, wherein said drive means includes a variable voltage power supply whose output voltage is variable between two voltage levels, the particular voltage level being dependent upon the magnitude of lens displacement necessary to focus an image of said particular subject at said image plane.

Claim 15

The apparatus of claim 12, wherein said drive means includes a bridge-type switching circuit for connecting said variable voltage power supply to said variable speed reversible motor.

Claim 16

The apparatus of claim 13, wherein said switching circuit utilizes solid state switching devices.