Garret J Caterino

US Patent:

57015252, Dec 23, 1997

Filed:

Dec 3, 1996

Appl. No.:

8/758338

Inventors:

Garret J. Caterino - Maynard MA
Patrick W. Hopkins - Chelmsford MA
Elliott S. Strizhak - Millis MA

Assignee:

Polaroid Corporation - Cambridge MA

International Classification:

G03B 908
G03B 1334
G01D 536

US Classification:

396132

Abstract:

A camera shutter and focus encoder assembly comprises an encoder mask fixed in a camera housing and having an arcuate window having alternating opaque and transmissive portions, and an encoder sheet mounted in the housing in abutting relationship with the encoder mask, the encoder sheet being movable with exposure blades and the focus lens of the camera and having an arcuate window having alternating opaque and transmissive portions therein. Means are provided for pressing the encoder mask and the encoder sheet together with the mask and sheet windows in registration with each other. A sensor passes pulses of light through the mask and sheet windows when the transmissive portions thereof are in registration and detects the pulses of light, converts the light pulses to electrical signals, and transmits the electrical signals. A controller receives the electrical signals and determines therefrom the position and direction of movement of the shutter blades, compares the blade position and movement direction with a preselected program and sends to a motor a signal instructing any required compensating shutter blade movement change, and in like manner monitors the focus assembly and sends to the motor a signal instructing any required compensating lens movement change.