Camera focus detecting device

Claim 2

An automatic focus detecting device for a camera having a self-scanning type photoelectric conversion element comprising: a switching circuit for switching a self-scanning type photoelectric conversion element array for brightness detection and brightness modulation; circuit means for determining an average value of brightness at the time of brightness modulation operating as a static type photoelectric conversion element; means for switching said self-scanning type photoelectric conversion element array at the start of focus detection to independent connections for brightness modulation; means for converting an output of said switching means to a signal having a variable drive frequency, said signal being coupled to said self-scanning type photoelectric conversion element wherein said self-scanning type photoelectric conversion element array is switched to a parallel connection for brightness detection so that said self-scanning type photoelectric conversion element group is driven by said signal having a variable drive frequency; and focus detection processing means for controlling a drive circuit of a photographing lens thereby to perform focus detection in response to outputs of said self-scanning type photoelectric conversion element group.

Claim 3

A device as claimed in claim 1 wherein said brightness modulation and brightness detection are alternately carried out.

Claim 4

A device as claimed in claim 1 wherein said brightness modulation is carried out once in every several to several tens of brightness detections.

Claim 5

A device as claimed in claim 1 further comprising means for weighting a brightness modulation output.

Claim 7

An automatic focus detecting device comprising: a self-scanning type photoelectric conversion element array; brightness detecting means; focus detecting means; switch means for coupling outputs of photodiode elements of said array in parallel and to said brightness detecting means for a brightness detection operation and alternately in serial fashion to said focus detecting means; and means for varying a scanning frequency of said array in response to an output of said brightness detecting means.

Claim 8

An automatic focus detecting device comprising: a self-scanning type photoelectric conversion element array; brightness detecting means; focus detecting means; switch means for coupling outputs of photodiode elements of said array in parallel and to said brightness detecting means for a brightness detection operation and alternately in serial fashion to said focus detecting means; and means for varying a scanning frequency of said array in response to an output of said brightness detecting means.

Claim 9

The focus detecting device of claim 6 wherein said switching means comprises: a plurality of AND gates each having one input coupled to an output of a scanning circuit of said array and a second input coupled in common with each of the second inputs of said AND gates; a first plurality of electronic switch means each of which has a control input coupled to an output of one of said AND gates and having one switch terminal coupled to one of said photodiode elements and a second switch terminal coupled in common with each of the second switch terminals of said first plurality electronic switch means; means for producing a control signal in response to a start switch; a second electronic switch means having a control input coupled to receive said control signal and having one switch terminal coupled to an input of said brightness detecting means and a second switch terminal coupled to said commonly coupled second switch terminals of said first plurality of electronic switches; an inverter having an input coupled to receive said control signal and an output coupled to said commonly coupled second inputs of said AND gates; and a third electronic switch means having one switch terminal coupled to said second switch terminal of said second electronic switch means, a second switch terminal coupled to an input of said focus detecting means and a control input coupled to said output of said inverter.

Claim 10

The focus detecting device of claim 7 further comprising: a second inverter having an input coupled to said output of said first inverter; a fourth electronic switch means having first a switch terminal coupled to said second switch terminal of said second electronic switch means and a second switch terminal coupled to a biasing source.

Claim 11

The focus detecting device of claim 6, 7, or 8 further comprising: means for positioning a camera lens in response to an output of said focus detecting means.