Focusing device

Claim 2

A focusing device comprising: (a) light emitting means for projecting light onto an object to be photographed, said light emitting means performing a first cycle of light emission in response to a start signal of the focusing device; (b) light receiving means positioned to receive the reflection of the projected light of said light emitting means, said light receiving means having photosensitive elements provided with two light receiving areas; (c) means for measuring the degree of sharpness of an image of the object on the basis of the signals from said light receiving means, said measuring means converting the light of the first cycle incident on said two light receiving areas to electrical signals, obtaining the difference between the signals, and determining the degree of image sharpness by said signal difference; and (d) means for controlling said light emitting means, said means determining the time space from the first cycle of light emission of said light emitting means to the next cycle depending on the signal of said measuring means and actuating said light emitting means at the termination of duration of said time space.

Claim 3

A focusing device comprising: (a) light emitting means for projecting light onto an object to be photographed; (b) light receiving means for receiving the reflection of the projected light of said light emitting means; (c) means for detecting a focused state of an object image based on the signal from said light receiving means; and (d) light emission control means, said means receptive of a detection signal of said focused state detecting means controlling the light emission interval of said light emitting means, so that when said detection signal is far away from an in-focus region, said light emission interval is increased, and when it is close to the in-focus region, the light emission interval is shortened.

Claim 4

A focusing device comprising: (a) light emitting means for projecting light onto an object to be photographed; (b) light receiving means for receiving the reflection of the projected light of said light emitting means; (c) means for detecting a focused state of an object image based on the signal from said light receiving means; and (d) light emission control means, said means receptive of a detection signal of said focused state detecting means controlling the light emission interval of said light emitting means, so that when said detection signal is far away from an in-focus region, said light emission interval is increased, and when it is close to the in-focus region, the light emission interval is shortened.

Claim 5

A focusing device according to claim 1 or 2, wherein said light emission control means includes a counter which is arranged to control the light emitting time interval of said light emitting means and to determine the light emitting time interval according to the signal from said focused state detecting means.

Claim 6

A focusing device comprising: (a) light emitting means for emitting light for the first time by a start signal of said focusing device and then recycling the light emitting operation; (b) means for driving motion of an image forming lens; (c) light receiving means having two light receiving areas to receive the reflection of said first cycle of light emission; (d) means for computing the difference between the photo signals from said two light receiving areas and sampling signals representing this difference; (e) means receptive of the output signal of said sampling meaas for detecting a focused state of an object image; (f) means receptive of the signal of said focused state detecting means for producing a count signal dependent on the focused state to determine the time space from the first cycle of light emission to the next cycle of light emission; and (g) means for controlling said lens drive means, said control means having gate means for controlling the current supply to said lens drive means and how long said gate means is gated off being controlled by the signal of said time interval determining means.

Claim 7

A focusing device comprising: (a) light emitting means for emitting light for the first time by a start signal of said focusing device and then recycling the light emitting operation; (b) means for driving motion of an image forming lens; (c) light receiving means having two light receiving areas to receive the reflection of said first cycle of light emission; (d) means for computing the difference between the photo signals from said two light receiving areas and sampling signals representing this difference; (e) means receptive of the output signal of said sampling meaas for detecting a focused state of an object image; (f) means receptive of the signal of said focused state detecting means for producing a count signal dependent on the focused state to determine the time space from the first cycle of light emission to the next cycle of light emission; and (g) means for controlling said lens drive means, said control means having gate means for controlling the current supply to said lens drive means and how long said gate means is gated off being controlled by the signal of said time interval determining means.

Claim 8

A focusing device comprising: (a) light emitting means for emitting light for the first time by a start signal of said focusing device and then recycling the light emitting operation; (b) means for driving motion of an image forming lens; (c) light receiving means having two light receiving areas to receive the reflection of said first cycle of light emission; (d) means for computing the difference between the photo signals from said two light receiving areas and sampling signals representing this difference; (e) means receptive of the output signal of said sampling means for detecting a focused state of an object image; (f) means receptive of the signal of said focused state detecting means for producing a count signal dependent on the focused state to determine the time space from the first cycle of light emission to the next cycle of light emission; and (g) means for controlling said lens drive means, said control means having a first comparing means receptive of the signal of said sampling meansfor discriminating whether the focused state is a far focus state of a near focus state, gating means for controlling the current supply to said lens drive means to be opened by the signal of said first comparing means, and a logic gate circuit being rendered operative by the signal from said time interval determining means to produce an output signal for closing said gating means.

Claim 9

A focusing device comprising: (a) light emitting means for emitting light for the first time by a start signal of said focusing device and then recycling the light emitting operation; (b) means for driving motion of an image forming lens; (c) light receiving means having two light receiving areas to receive the reflection of said first cycle of light emission; (d) means for computing the difference between the photo signals from said two light receiving areas and sampling signals representing this difference; (e) means receptive of the output signal of said sampling means for detecting a focused state of an object image; (f) means receptive of the signal of said focused state detecting means for producing a count signal dependent on the focused state to determine the time space from the first cycle of light emission to the next cycle of light emission; and (g) means for controlling said lens drive means, said control means having a first comparing means receptive of the signal of said sampling meansfor discriminating whether the focused state is a far focus state of a near focus state, gating means for controlling the current supply to said lens drive means to be opened by the signal of said first comparing means, and a logic gate circuit being rendered operative by the signal from said time interval determining means to produce an output signal for closing said gating means.