초록 ▼

A bimodal automatic lens focussing apparatus including detection and switching means for detecting a loss in a localized focal condition and switching to a search mode wherein the objective lens is scanned between its outer limits to reacquire focus. Photodiode arrays sense respective light images o

A bimodal automatic lens focussing apparatus including detection and switching means for detecting a loss in a localized focal condition and switching to a search mode wherein the objective lens is scanned between its outer limits to reacquire focus. Photodiode arrays sense respective light images on either side of the desired focal plane, and the resulting signals are processed to drive the lens to the desired focal plane. A level discriminator monitors the processed signals. Upon detection of a loss of the localized focus condition a mode switch is gated to couple a ramp generator to the lens driver. The lens is scanned between its outer limits until the level discriminator again detects the localized focus condition and the ramp generator is decoupled from the lens driver.

대표청구항 ▼

In automatic lens focussing apparatus having an objective lens to be placed at a desired focal plane, a focus sensor located on either side of the focal plane for sensing respective light images, processing means for processing information from said sensors relating to the intensity of said light im

In automatic lens focussing apparatus having an objective lens to be placed at a desired focal plane, a focus sensor located on either side of the focal plane for sensing respective light images, processing means for processing information from said sensors relating to the intensity of said light images, and drive means responsive to said processed information for moving said lens to the desired focal plane in a localized focal condition, the improvement comprising: each of said focus sensors including, a photodiode array sensing a light image at respective locations, and scanning means for scanning said photodiode array to provide respective signals to said processing means corresponding to the relative intensity of said light images; and detection-switch means intermediate said processing means and said drive means and responsive to said processed information for selectively initiating a search mode wherein said lens is moved to scan and reacquire said localized focal condition upon detection of a loss of said localized focal condition.