Digital cameras with triangulation autofocus system

Abstract

Digital cameras with triangulation auto focus systems include a spot beam emitter than can be used to project a spot onto a subject that is captured in an image and used to electronically automatically determine a subject to camera distance.

1 . A digital camera, comprising:
 a camera body; and   a spot beam emitter held by the camera body, the spot beam emitter being configured to concurrently project a plurality of light spots onto a target subject that is able to be captured in a digital image of a target subject taken by the camera;   a camera lens held by the camera body disposed proximate the spot beam emitter, wherein the digital camera comprises a triangulation auto focus system that calculates measures of distance of the spots to focus the camera lens.   
     
     
         2 . The digital camera of  claim 1 , characterized in that the digital camera is part of a portable electronic communications device. 
     
     
         3 . The digital camera of  claim 1 , further comprising a camera image sensor in communication with the camera lens, the camera image sensor being configured to act as a receiver in the triangulation auto focus system. 
     
     
         4 . The digital camera of  claim 1 , further comprising a digital camera image sensor configured to communicate with the spot beam emitter. 
     
     
         5 . The digital camera of  claim 4 , further comprising an automatic exposure control circuit in communication with the spot beam emitter to control the duration and/or intensity of the projected spot. 
     
     
         6 . The digital camera of  claim 1 , further comprising a collimating lens in the light transmission path configured to collimate the light from the spot beam emitter 
     
     
         7 . The digital camera of  claim 1 , further comprising one or more of the following: a transparent diffraction grating, a cylindrical lens or a holographic diffraction grating, in communication with the spot beam emitter to generate the light spots in the image. 
     
     
         8 . The digital camera of  claim 1 , wherein the spot beam emitter is configured to operate with a spot beam pulse having a spot duration of about 1 ms or less. 
     
     
         9 . The digital camera of  claim 1 , further comprising a contrast auto focus system. 
     
     
         10 . The digital camera of  claim 1 , further comprising a light intensity control circuit in communication with the spot beam emitter. 
     
     
         11 . The digital camera of  claim 1  wherein the spot beam emitter comprises a laser, the camera further comprising a pulse control circuit. 
     
     
         12 . The digital camera of  claim 1 , wherein the spot beam emitter projects a light that is in a visible part of the light spectrum. 
     
     
         13 . The digital camera of  claim 1 , further comprising an automatic exposure control used to time a duration of the projected spot and to monitor a brightness of a target image subject. 
     
     
         14 . The digital camera of  claim 1 , further comprising a control circuit that is configured to selectively operate the camera in a still image camera mode and in a video recording mode, wherein the control circuit is configured to control emission of a spot beam pulse during the still image and video recording modes, and wherein the control circuit is configured to prevent emission of the spot beam pulse during acquisition of selected images. 
     
     
         15 . The digital camera of  claim 1 , wherein the device is configured to electronically automatically compare a region of interest between electronically stored sequential first and second images to determine positional data associated with a light spot generated by the spot beam emitter, then electronically automatically calculate a distance of the target subject from the camera based on the determined positional data and adjust the position of the lens to the focus position based on the calculated distance. 
     
     
         16 . The digital camera of  claim 15 , wherein the device comprises a circuit that is configured to automatically electronically register and/or align a region of interest in the first and second images to thereby provide motion image stabilization in a still image. 
     
     
         17 . The digital camera of  claim 1 , further comprising a controller that is configured to automatically operate the triangulation auto focus system, wherein the controller (i) controllably operates the spot beam emitter to provide the spots that are visible in a captured digital image, (ii) calculates a camera to subject triangulation measure of distance for each of the plurality of spots and (iii) automatically moves the camera lens to a focus position based on a closest calculated spot distance to focus the camera. 
     
     
         18 . The digital camera of  claim 17 , wherein the controller is further configured to electronically generate a difference image of pixel values obtained by subtracting pixel values from registered first and second images; and electronically identify light spot locations associated with the projected light spots in the difference image. 
     
     
         19 . The digital camera of  claim 18 , wherein the controller electronically identifies the light spot locations using pixel color. 
     
     
         20 . The digital camera of  claim 1 , wherein the camera is configured with a circuit that calculates a camera to subject distance “u” according to:
     u=fs/np    
 
       where “n” represents a displacement measured in number of pixels in position between a light spot in the image and a center of the image, “f” is a focal length of the camera lens, “s” is a distance between the camera lens and an emitter axis for emitter(s) used to generate the projected light spots, and “p” is pixel pitch.