Lens control apparatus
AssigneeCanon Kabushiki Kaisha
InventorTaeko Tanaka
Life of this patent
Estimating the term…
Abstract
A lens control apparatus drives a lens with a sine wave by means of a pulse motor and detects the position of the lens by counting the number of pulses during the driving of the pulse motor, and stores a stop phase which is reached by a rotor when the pulse motor is brought to a driving-stopped state. When the lens control apparatus is to move the lens to an initial position and initialize a counter for detecting the position of the lens, the lens control apparatus corrects the count value of the counter by using information indicative of the stored stop phase of the rotor.
Claims20
A pulse motor control apparatus comprising:
- driving means for driving a pulse motor with an approximate sine wave;
- counting means for counting the number of pulses during driving of the pulse motor;
- and
- storage means for storing information relative to a stop phase position of a rotor when the pulse motor is brought to a driving-stopped state.
A pulse motor control method comprising the steps of:
- storing, in a recording medium, information relative to a stop phase position of a rotor when a pulse motor is brought to a driving-stopped state;
- and
- correcting a count value of counting means for counting the number of pulses during driving of the pulse motor, at the time of a start of the driving of the pulse motor, by using the information relative to the stop phase position stored in the recording medium.
A pulse motor control method comprising the steps of:
- storing, in a recording medium, information relative to a stop phase position which is reached by a rotor when a pulse motor is brought to a driving-stopped state;
- and
- correcting a start excitation phase required for driving of the pulse motor, at the time of a start of the driving of the pulse motor, by using information relative to the stop phase position stored in the recording medium.
A lens control apparatus comprising:
- at least one lens group which is movable in parallel with an optical axis;
- a pulse motor for moving said lens group;
- driving means for driving said pulse motor with an approximate sine wave;
- lens position detecting means for detecting a position of said lens group by counting the number of pulses during driving of said pulse motor;
- initializing means for initializing said lens position detecting means by moving said lens group;
- storage means for storing information relative to a stop phase position of a rotor when said pulse motor is brought to a driving-stopped state;
- and
- correcting means for correcting, when said initializing means is to initialize said lens position detecting means by moving said lens group, a count value of said lens position detecting means by using the information stored in said storage means.
A pulse motor control apparatus comprising:
- driving means for driving a pulse motor with a PWM control;
- counting means for counting the number of pulses during driving of the pulse motor;
- and
- storage means for storing information relative to a stop phase position of a rotor when the pulse motor is brought to a driving-stopped state.
A video camera apparatus comprising:
- at least on lens group which is movable in parallel with an optical axis;
- a pulse motor for moving said lens group;
- driving means for driving said pulse motor with an approximate sine wave;
- lens position detecting means for detecting a position of said lens group by counting the number of pulses during driving of said pulse motor;
- initializing means for initializing said lens position detecting means by moving said lens group;
- storage means for storing information relative to a stop phase position of a rotor when said pulse motor is brought to a driving-stopped state;
- and
- correcting means for correcting, when said initializing means is to initialize said lens position detecting means by moving said lens group, a count value of said lens position detecting means by using the information stored in said storage means.
Dependencies are inferred from the claim text.