Distance measuring apparatus for camera

Claim 2

A distance measuring apparatus comprising: light projection means for selectively setting into a first light emitting state for projecting light onto an area of relatively narrow range and a second light emitting state for projecting light onto an area of a range which is wider than the range of the first light emitting state; a pair of optical position detecting means arranged with said light projecting means disposed therebetween, each of said optical position detecting means including a pair of electrodes and outputting signal currents corresponding to the incident position of light which has been projected and reflected from a subject; and distance deriving means for deriving the distance (1/D 1 ) to the subject according to the equation of ##EQU33## (where k= ##EQU34## A S and A M are constants, and h 2 is the ratio of an area occupied by the subject with respect to the entire illuminated range) based on a value (1/D S ) dependent on the ratio of the signal currents derived from the electrodes of said optical position detecting means and a value (i ss ) dependent on the sum of the signal currents in the first light emitting state and based on a value (1/D M ) dependent on the ratio of the signal currents derived from the electrodes of said optical position detecting means and a value (i SM ) dependent on the sum of the signal currents in the second light emitting state.

Claim 3

The distance measuring apparatus according to claim 1, wherein said light projecting means includes a light projecting lens and a light emitting element disposed with the center thereof aligned with the optical axis of said light projecting lens, said light emitting element having a spot light emitting section for illuminating a portion only near the optical axis and an area light emitting section for illuminating a wide range.

Claim 4

The distance measuring apparatus according to claim 2, wherein said distance deriving means derives the value (1/D S ) dependent on the ratio of the signal currents derived from the electrodes of said optical position detecting means and the value (i SS ) dependent on the sum of the signal currents in a state in which said spot light emitting section is activated, and derives the value (1/D M ) dependent on the ratio of signal currents derived from the electrodes of said optical position detecting means and the value (i SM ) dependent on the sum of the signal currents in a state in which said spot light emitting section and said area light emitting section are activated.

Claim 5

The distance measuring apparatus according to claim 1, wherein said pair of optical position detecting means includes a pair of position sensing devices (PSDs) formed on the same substrate; and a prism for guiding the projected light incident on the subject via a pair of light reception lenses and reflected from the subject towards said pair of PSDs.

Claim 6

A distance measuring apparatus comprising: light projection means for selectively setting into a first light emitting state for projecting light onto an area of relatively narrow range and a second light emitting state for projecting light onto an area of a range which is wider than the range of the first light emitting state; a pair of optical position detecting means arranged with said light projecting means disposed therebetween; first deriving means for deriving a value (1/D S ) dependent on the ratio of the signal currents derived from respective electrodes of said optical position detecting means in the first light emitting state and a value (1/D M ) dependent on the ratio of signal currents derived from the electrodes of said optical position detecting means in the second light emitting state; comparing means for comparing the two values dependent on the ratio of the signal currents derived by said first deriving means with each other; and distance determining means for determining the distance to the subject based on the result of comparison by said comparing means.

Claim 7

A distance measuring apparatus comprising: light projection means for selectively setting into a first light emitting state for projecting light onto an area of relatively narrow range and a second light emitting state for projecting light onto an area of a range which is wider than the range of the first light emitting state; a pair of optical position detecting means arranged with said light projecting means disposed therebetween; first deriving means for deriving a value (1/D S ) dependent on the ratio of the signal currents derived from respective electrodes of said optical position detecting means in the first light emitting state and a value (1/D M ) dependent on the ratio of signal currents derived from the electrodes of said optical position detecting means in the second light emitting state; comparing means for comparing the two values dependent on the ratio of the signal currents derived by said first deriving means with each other; and distance determining means for determining the distance to the subject based on the result of comparison by said comparing means.

Claim 8

The distance measuring apparatus according to claim 1, further comprising second deriving means for deriving a value (i SS ) dependent on the sum of the signal currents derived from the respective electrodes of said optical position detecting means in the first light emitting state and a value (i SM ) dependent on the sum of the signal currents derived from the respective electrodes of said optical position detecting means in the second light emitting state, and wherein said distance determining means selects 1/D S as the distance to the subject when the result of comparison by said comparing means indicates that (1/D S )-(1/D M )>Δ (Δ is a predetermined amount), selects [(1/D S )+(1/D M )]/2 as the distance to the subject when |(1/D S )-(1/D M )≦Δ, and derives the distance (1/D 1 ) to the subject in the other case according to ##EQU35## where ##EQU36## A S and A M are constants, and h 2 is the ratio or an area occupied by the subject with respect to the entire illuminated range.

Claim 9

A distance measuring apparatus comprising: light projection means for selectively setting into a first light emitting state for projecting light onto an area of relatively narrow range and a second light emitting state for projecting light onto an area of a range which is wider than the range of the first light emitting state; a first optical position detecting element, disposed at a distance of base length from said light projection means, for receiving light which is projected from said light projection means onto the subject and reflected from the subject, said first optical position detecting element outputting signal currents from a pair of electrodes according to the light incident position; a second optical position detecting element, disposed on the opposite side of said first optical position detecting element with respect to said light projection means, at a distance of the base length from said light projection means, for receiving light which is projected from said light projection means onto the subject and reflected from the subject, said second optical position detecting element outputting signal currents from a pair of electrodes according to the light incident position; first deriving means for deriving a first signal current from one of the paired electrodes of said first optical position detecting means and one of the paired electrodes of said second optical position detecting means, deriving a second signal current from the other of the paired electrodes of said first optical position detecting means and the other of the paired electrodes of said second optical position detecting means, and deriving the ratio of the first and second signal currents; second deriving means for deriving a value corresponding to the sum of the first and second signal currents; and distance determining means for determining the distance to the subject based on outputs of said first and second deriving means in the first light emitting state and outputs of said first and second deriving means in the second light emitting state.

Claim 10

A distance measuring apparatus comprising: light projection means for selectively setting into a first light emitting state for projecting light onto an area of relatively narrow range and a second light emitting state for projecting light onto an area of a range which is wider than the range of the first light emitting state; a first optical position detecting element, disposed at a distance of base length from said light projection means, for receiving light which is projected from said light projection means onto the subject and reflected from the subject, said first optical position detecting element outputting signal currents from a pair of electrodes according to the light incident position; a second optical position detecting element, disposed on the opposite side of said first optical position detecting element with respect to said light projection means, at a distance of the base length from said light projection means, for receiving light which is projected from said light projection means onto the subject and reflected from the subject, said second optical position detecting element outputting signal currents from a pair of electrodes according to the light incident position; first deriving means for deriving a first signal current from one of the paired electrodes of said first optical position detecting means and one of the paired electrodes of said second optical position detecting means, deriving a second signal current from the other of the paired electrodes of said first optical position detecting means and the other of the paired electrodes of said second optical position detecting means, and deriving the ratio of the first and second signal currents; second deriving means for deriving a value corresponding to the sum of the first and second signal currents; and distance determining means for determining the distance to the subject based on outputs of said first and second deriving means in the first light emitting state and outputs of said first and second deriving means in the second light emitting state.

Claim 11

The distance measuring apparatus according to claim 7, wherein outputs of said first and second deriving means in the first light emitting state are respectively expressed by 1/D S and i SS , and outputs of said first and second deriving means in the second light emitting state are respectively expressed by 1/D M and i SM , said distance determining means determines the distance (1/D 1 ) to the subject according to the equation of ##EQU37## where ##EQU38## A S and A M are constants, and h 2 is the ratio of an area occupied by the subject with respect to the entire illuminated range.

Claim 12

The distance measuring apparatus according to claim 7, further comprising comparing means for comparing the result of the deriving operation by said first deriving means in the first light emitting state and the result of the deriving operation by said first deriving means in the second light emitting state, and wherein said distance determining means determines the distance to the subject according to the magnitude relation between the results of said first and second deriving means derived by said comparing means.

Claim 13

The distance measuring apparatus according to claim 9, wherein outputs of said first and second deriving means in the first light emitting state are respectively expressed by 1/D S and i SS , and outputs of said first and second deriving means in the second light emitting state are respectively expressed by 1/D M and i SM , said distance determining means selects 1/D S as the distance to the subject when the result of comparison by said comparing means indicates that (1/D S )-(1/D M )>Δ (Δ is a predetermined amount), selects [(1/D S )+(1/D M )]/2 as the distance to the subject when (1/D S )-(1/D M )≦Δ, and derives the distance (i/D 1 ) to the subject in the other case according to the equation of ##EQU39## where ##EQU40## A S and A M are constants, and h 2 is the ratio of an area occupied by the subject with respect to the entire illuminated range.

Claim 14

A distance measuring apparatus for camera comprising: light emitting means for selectively setting into a first light emitting state for emitting distance measuring light to only part of a distance measuring area and a second light emitting state for emitting distance measuring light to the entire portion of the distance measuring area; light reception means having a pair of optical position detecting elements arranged with said light emitting means disposed therebetween, for receiving distance measuring light which is projected from said light emitting means onto the subject and reflected from the subject and supplying outputs corresponding to the light receiving position from two electrodes; light emission controlling means for selecting the light emitting state of said light emitting means and causing said light emitting means to emit the distance measuring light plural times; output generating means for combining the outputs from said light reception means, and generating first and second output values obtained by integrating outputs which are respectively dependent on the ratio and sum of the outputs from the respective electrodes of said pair of optical position detecting elements in response to the illumination of distance measuring light by said light emission controlling means; and deriving means for determining a distance to the subject based on the first and second output values generated from said output generating means when said light emitting means is set in the first light emitting state and the first and second output values generated from said output generating means when said light emitting means is set in the second light emitting state.

Claim 15

A distance measuring apparatus for camera comprising: light emitting means for selectively setting into a first light emitting state for emitting distance measuring light to only part of a distance measuring area and a second light emitting state for emitting distance measuring light to the entire portion of the distance measuring area; light reception means having a pair of optical position detecting elements arranged with said light emitting means disposed therebetween, for receiving distance measuring light which is projected from said light emitting means onto the subject and reflected from the subject and supplying outputs corresponding to the light receiving position from two electrodes; light emission controlling means for selecting the light emitting state of said light emitting means and causing said light emitting means to emit the distance measuring light plural times; output generating means for combining the outputs from said light reception means, and generating first and second output values obtained by integrating outputs which are respectively dependent on the ratio and sum of the outputs from the respective electrodes of said pair of optical position detecting elements in response to the illumination of distance measuring light by said light emission controlling means; and deriving means for determining a distance to the subject based on the first and second output values generated from said output generating means when said light emitting means is set in the first light emitting state and the first and second output values generated from said output generating means when said light emitting means is set in the second light emitting state.

Claim 16

The distance measuring apparatus according to claim 11, wherein said deriving means has a plurality of equations for deriving the distance to the subject and includes means for comparing the first output value generated from said output generating means when said light emitting means is set in the first light emitting state with the first output value generated from said output generating means when said light emitting means is set in the second light emitting state and selecting one of said plurality of equations according to the result of comparison.

Claim 17

The distance measuring apparatus according to claim 11, wherein said light emitting means includes a light emitting element constructed by a plurality of light emitting sections and an electrode formed to surround said plurality of light emitting sections, the light emitting section lying at the central portion of said light emitting means is activated in the first light emitting state, and all of said plurality of light emitting sections are activated in the second light emitting state.

Claim 18

A distance measuring apparatus for camera comprising: light emitting means for selectively setting into a first light emitting state for emitting distance measuring light to only part of a distance measuring area and a second light emitting state for emitting distance measuring light to the entire portion of the distance measuring area; light reception means having a pair of light reception lenses arranged with said light emitting means disposed therebetween and a pair of optical position detecting elements for receiving light beams received by said light reception lenses, for receiving light which is projected from said light emitting means onto the subject and reflected from the subject by said light reception lenses and for generating outputs corresponding to the light receiving position from said pair of optical position detecting elements; and deriving means for deriving a distance to the subject based on the output from said light reception means, said deriving means deriving the distance to the subject according to the output generated from said light reception means when said light emitting means is set in the first light emitting state and the output generated from said light reception means when said light emitting means is set in the second light emitting state.

Claim 19

A distance measuring apparatus for camera comprising: light emitting means for selectively setting into a first light emitting state for emitting distance measuring light to only part of a distance measuring area and a second light emitting state for emitting distance measuring light to the entire portion of the distance measuring area; light reception means having a pair of light reception lenses arranged with said light emitting means disposed therebetween and a pair of optical position detecting elements for receiving light beams received by said light reception lenses, for receiving light which is projected from said light emitting means onto the subject and reflected from the subject by said light reception lenses and for generating outputs corresponding to the light receiving position from said pair of optical position detecting elements; and deriving means for deriving a distance to the subject based on the output from said light reception means, said deriving means deriving the distance to the subject according to the output generated from said light reception means when said light emitting means is set in the first light emitting state and the output generated from said light reception means when said light emitting means is set in the second light emitting state.

Claim 20

The distance measuring apparatus according to claim 14, wherein said light emitting means includes a light emitting element constructed by a plurality of light emitting sections and an electrode formed to surround said plurality of light emitting sections, the light emitting section lying at the central portion of said light emitting means is activated in the first light emitting state, and all of said plurality of light emitting sections are activated in the second light emitting state.

Claim 21

The distance measuring apparatus according to claim 14, wherein said light reception means outputs currents corresponding to the light receiving position from respective electrodes of said optical position detecting elements; and said deriving means derives first and second output values which are respectively dependent on the ratio and sum of the currents obtained from the electrodes of said optical position detecting elements when said light emitting means is set in the first light emitting state, derives third and fourth output values which are respectively dependent on the ratio and sum of the currents obtained from the electrodes of said optical position detecting elements when said light emitting means is set in the second light emitting state, and derives the distance to the subject based on the above four output values.

Claim 22

The distance measuring apparatus according to claim 16, wherein said deriving means has a plurality of equations used for deriving the distance to the subject and includes means for comparing the first output value with the third output value and selecting one of said plurality of equations according to the result of comparison.

Claim 23

The distance measuring apparatus according to claim 14, wherein said light reception means includes means for deflecting light beams incident on said light reception lenses and the light beams deflected by said deflection means are input to said pair of optical position detecting elements.

Claim 24

A distance measuring apparatus for camera comprising: light emitting means for selectively setting into a first light emitting state for emitting distance measuring light onto a preset area and a second light emitting state for emitting distance measuring light onto a wide angle area containing the preset area illuminated in the first light emitting state; light reception means for receiving light which is projected from said light emitting means onto the subject and reflected from the subject, and outputting an output corresponding to the received light position; and determining means for determining the distance to the subject based on the output from said light reception means, said determining means determining the distance to the subject based on an output generated from said light reception means when said light emitting means is set in the first light emitting state and an output generated from said light reception means when said light emitting means is set in the second light emitting state.

Claim 25

A distance measuring apparatus for camera comprising: light emitting means for selectively setting into a first light emitting state for emitting distance measuring light onto a preset area and a second light emitting state for emitting distance measuring light onto a wide angle area containing the preset area illuminated in the first light emitting state; light reception means for receiving light which is projected from said light emitting means onto the subject and reflected from the subject, and outputting an output corresponding to the received light position; and determining means for determining the distance to the subject based on the output from said light reception means, said determining means determining the distance to the subject based on an output generated from said light reception means when said light emitting means is set in the first light emitting state and an output generated from said light reception means when said light emitting means is set in the second light emitting state.

Claim 26

The distance measuring apparatus according to claim 19, wherein said light emitting means includes a light emitting element constructed by a plurality of light emitting sections and an electrode formed to surround said plurality of light emitting sections, only the light emitting section lying at the central portion of said light emitting means is activated in the first light emitting state, and all of said plurality of light emitting sections are activated in the second light emitting state.

Claim 27

The distance measuring apparatus according to claim 19, wherein said light reception means has a light reception lens arranged at a distance of base length from said light emitting means and an optical position detecting element for receiving a light beam received by said light reception lens, said light reception lens receiving light which is projected from said light emitting means onto the subject and reflected from the subject and said optical position detecting element supplying outputs corresponding to the light receiving position from electrodes thereof; and said determining means derives first and second output values which are respectively dependent on the ratio and sum of the currents derived from the electrodes of said optical position detecting means when said light emitting means is set in the first state and derives third and fourth output values which are respectively dependent on the ratio and sum of the currents derived from the electrodes of said optical position detecting means when said light emitting means is set in the second state and determines the distance to the subject based on the four output values.

Claim 28

The distance measuring apparatus according to claim 19, wherein said determining means has a plurality of equations for deriving the distance to the subject and includes means for comparing a first output value generated from said output generating means when said light emitting means is set in the first light emitting state with a second output value generated from said output generating means when said light emitting means is set in the second light emitting state and selecting one of said plurality of equations according to the result of comparison.