JP2002031526A - Distance measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance measuring apparatus capable of being reduced in cost and size and making distance measurements at high performance. SOLUTION: In one embodiment, the distance measuring apparatus includes a light projecting means for projecting distance-measuring light; light splitting means for splitting the distance-measuring light in plural directions; a light receiving means for receiving the distance-measuring light projected and split through the light splitting means and reflected from the subject of distance measurement; and a detecting means for detecting the distance to the subject based on an output of the light receiving means. The light splitting means comprise a plurality of electrically controllable diffraction or reflection optical elements split apart from one another.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a distance measuring device,
In particular, the present invention relates to a multipoint distance measuring apparatus that can be mounted for AF such as a camera.

[0002]

2. Description of the Related Art Conventionally, there has been known an active type distance measuring device capable of measuring a distance in a plurality of areas in a photographing screen.

As such an active type distance measuring device, a distance measuring device in which a plurality of light emitting elements respectively corresponding to a plurality of distance measuring areas are provided, and the light emitting elements are sequentially emitted to measure the distance in the plurality of areas is known. It is.

A distance measuring device disclosed in Japanese Patent Application Laid-Open No. 6-242368 measures a distance in a plurality of distance measuring areas by mechanically scanning a light projecting element and projecting light. .

Japanese Patent Laid-Open Publication No. Hei 6-242368 has a rotatable diffraction grating in a light-projecting optical path of a fixed light-emitting element, and mechanically scans the diffraction grating to project light. By doing so, a distance measuring device that performs distance measurement for a plurality of distance measurement areas is also disclosed.

A distance measuring device disclosed in Japanese Patent Application Laid-Open No. 9-54242 divides a light projecting optical system into a plurality of light beams, divides a light beam projected by one light projecting element into a plurality of light beams, and projects the light beam. Auxiliary light that illuminates corresponding to the distance measurement area is used.

[0007]

When measuring a plurality of distance measuring areas on a photographing screen, providing a plurality of light emitting elements individually for the plurality of areas requires the same number of light emitting elements as the number of the distance measuring areas. Since it is necessary, there is a problem that the cost is increased.

The distance measuring device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-242368 requires a driving mechanism and space for mechanically scanning the light projecting element and the diffraction grating. Problem.

The distance measuring device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 9-54242 has a problem that the cost is increased due to the production of the divided light projecting lens.

Further, in this distance measuring device, since the projected light beam of one light projecting element is divided into a plurality of light beams, there is a problem that the amount of projected light is reduced and the distance measuring performance is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and it is possible to reduce the cost and size and to perform high-performance ranging. It is to provide a device.

[0012]

According to the present invention, in order to solve the above problems, (1) a light projecting means for projecting distance measuring light, and a light projecting means for dividing the distance measuring light into a plurality of directions. Light-receiving means for receiving reflected light of the distance-measuring light divided and projected through the light-dividing means from the object to be measured, and measuring the light based on the output of the light-receiving means. Detecting means for detecting the distance of the object to be distanced, wherein the light splitting means is an electrically controllable divided diffraction or reflection optical element. An apparatus is provided.

According to the present invention, in order to solve the above-mentioned problems, (2) the plurality of divided or diffractive optical elements selectively transmit the distance measuring light to a predetermined light projecting area. The distance measuring apparatus according to (1), which can be independently controlled so as to project light to the light source, is provided.

According to the present invention, in order to solve the above-mentioned problems, (3) the light splitting means comprises a plurality of the above-mentioned diffractive or reflective optical elements laminated, each of which is independently electrically controlled. By doing so, the distance measuring light can be selectively projected onto a predetermined area, thereby providing the distance measuring device according to (1) or (2).

According to the present invention, in order to solve the above-mentioned problems, (4) the diffractive or reflective optical element is characterized in that an electric signal is input to a diffraction grating formed of a polymer liquid crystal to be eliminated. (1) is provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing embodiments of the present invention with reference to the drawings, a conceptual configuration of a distance measuring apparatus according to the present invention will be described.

FIG. 1 is a block diagram showing a conceptual configuration of a distance measuring apparatus according to the present invention.

That is, the distance measuring apparatus according to the present invention has the configuration shown in FIG.
As shown in FIG. 1, a light projecting unit 1 having a light projecting unit for projecting light toward a subject, a light receiving unit 2 having a light receiving unit for receiving reflected light from the subject, and a projecting light from the projecting unit 1 Are electrically switchable and divided into a plurality of diffractive optical elements 3a, 3b, 3c,.
When the projected light from the light projecting unit 1 is projected through the b, 3c,..., the diffractive optical elements 3a, 3b, 3c. And the diffractive optical elements 3a, 3b, 3c ...
And a control unit (4) for calculating a distance to the subject based on an output from the light receiving unit (2) for receiving reflected light from the subject corresponding to the projected light passing through. It is configured as a distance measuring device.

Since a novel element is used in the present invention, the element will be described first.

First, a general diffractive optical element will be described.

(Explanation of Diffractive Optical Element) A general diffractive optical element (Diffractive Optical El)
element) is an optical element called DOE, which is based on a diffraction phenomenon.

As shown in FIG. 2, this general diffractive optical element has the following formula (1) when the incident angle is θ, the exit angle is θ ′, the diffraction order is m, and the pitch of the diffraction grating is d. , A diffraction phenomenon occurs.

Sin θ−sin θ ′ = mλ / d (1) When focusing on one diffraction order, for example, when the pitch d of the diffraction grating is continuously changed as shown in FIG.
An effect such as a lens for condensing the next diffracted light can be provided.

Next, an ESHOE (Electrically Swi) which is a diffractive optical element which can be electrically switched without using a mechanical mechanism used in the present invention.
Tachable Holographic Optical
al Element) will be described.

This ESHOE is similar in principle to the diffractive optical element.

This ESHOE is based on a phase-type volume hologram, and the hologram medium is a PDLC (p-type) which is a polymer dispersed liquid crystal composed of a mixture of a polymer and a liquid crystal.
oligomer Dipersed Liquid Cr
(ystal), a light having a spatial intensity distribution is irradiated, whereby a light distribution of the liquid crystal is generated according to the intensity distribution, thereby forming a hologram.

When an electric field is applied to this, the refractive index modulation is reduced and the hologram is erased.

The light distribution of the liquid crystal is reversible, and the hologram is restored again when the electric field is removed.

Once the hologram is recorded in this way, the hologram can be switched by turning on and off the electric field.

(1) Cell Structure (FIG. 4A) The cell has a structure in which a mixture of liquid crystal and monomer is sandwiched between a glass or plastic substrate coated with a transparent conductive film on the inside.

(2) Hologram preparation 1 Laser exposure (FIG. 4B) A cell is placed at the intersection of two laser beams where interference fringes occur.

The fringe pattern of a light beam depends on the phase difference between two light beams, a laser object light beam and a laser reference light beam, which are created by arranging a computer-generated diffraction element in the object light beam.

Thus, from a relatively simple grid,
Even complex optical trains can replace a significant number of refractive lenses.

(3) Hologram Preparation 2 Polymerization and Separation (FIG. 4 (c)) The interference pattern creates bright and dark surfaces that are regularly arranged in the cell gap.

During such exposure, the liquid crystal forms fine particles and diffuses into the darker areas, so that the monomer first begins to polymerize in the lighter areas.

As the exposure progresses, the monomers in the dark areas also polymerize, fixing the grains and fixing the stripe pattern.

(4) Grating Operation (FIG. 4 (d)) The polymerization process results in an alternating fixed structure of relatively pure polymer faces and dense liquid crystal grains.

Since the latter region has a different refractive index for the polymer (npＣＭnLCM), the recording process results in a volume hologram with defined and complex optical properties.

(5) Switching state (transparent state) (FIG. 4 (e) By applying an AC voltage, the polymer refractive index (n
The transparent cell is formed by deflecting the optical axis of the liquid crystal in the small particle so as to generate an effective refractive index effnLCM that matches p).

The above is a transmission type diffractive optical element ESH.
Although the OE has been described, the same manufacturing method and operation principle are applied to a reflection type diffractive optical element.

(First Embodiment) Next, a first embodiment in which the distance measuring apparatus of the present invention is specifically applied to a camera will be described.

FIG. 5 shows, as a first embodiment in which the distance measuring device of the present invention is specifically applied to a camera, a camera equipped with an active distance measuring device for measuring three points in a photographing screen. FIG. 3 is a block diagram showing the configuration of FIG.

That is, in the camera according to this embodiment, as shown in FIG. 5, first, a light emitting diode (LED) 10 as a light emitting element is driven by an LED driving circuit 11.

As shown in FIG. 6A described later, the light beam emitted from the LED 10 is transmitted to the light projecting lens 12, the ESHOEs 14 and 15 divided into a plurality of parts, and the ESHOEs.
In this case, three projected light beams 32, 3
Light is projected as 3 and 31.

The transparent portion 13 above the ESHOEs 14 and 15 is a portion through which the projected light beam 31 passes.

As shown in FIG. 6B, ESHOE1
4 and 15 are partially formed in the glass substrates 120 and 121.

The ESHOEs 14 and 15 have predetermined diffractive optical characteristics recorded in advance during the manufacturing process.

Glass substrate 12 corresponding to transparent portion 13
A space between 0 and 121 is filled with a transparent material such as a transparent resin.

Returning to FIG. 5, ESHOEs 14 and 15
It is designed to be driven by an ESHOE drive circuit 16.

When the ESHOEs 14 and 15 are driven, their diffractions are controlled on and off, respectively, to control the projection angle.

FIG. 6D shows the ESHOE driving circuit 16.
It is a figure showing in more detail about.

That is, as shown in FIG.
The AC power supply 83 and the electric switch element 81 in the ESHOE drive circuit 16 are connected to the SHOE 14.

The on / off of the electric switch element 81 is controlled by a microcomputer (CPU) 20.

Thus, application and non-application of the AC signal from the AC power supply 83 to the ESHOE 14 are controlled.

Similarly, ESHOE 15 includes ESHOE
AC power supply 84 and electric switch element 8 in drive circuit 16
2 are connected.

The CPU 20 of the electric switch element 82
The on / off is controlled by this.

Thus, application and non-application of the AC signal from the AC power supply 84 to the ESHOE 15 are controlled.

FIG. 6A shows a light projecting system including an optical system.

When the ESHOE 14 functions as a diffractive optical element, the ESHOE 14
The diffractive optical characteristics are recorded so as to diffract the light.

When the ESHOE 15 functions as a diffractive optical element, the diffractive optical characteristics are recorded so that the light beam emitted from the LED 10 is diffracted into the light beam 33.

The light beam emitted from the LED 10 passing through the transparent portion 13 above the ESHOEs 14 and 15 is as follows.
It becomes a projected light beam 31.

FIG. 6C is a diagram showing a light receiving system including an optical system.

The reflected light from the subject by the projected light beam 31 enters the light receiving section 41 of the distance measuring sensor 40 as a light receiving element via the light receiving lenses 18a and 18b.

Similarly, the reflected light from the subject by the projected light beam 32 enters the light receiving section 42 of the distance measuring sensor 40, which is a light receiving element, via the light receiving lenses 17a and 17b.

Further, similarly, with respect to the projected light beam 32, the reflected light from the subject is reflected by the light receiving lenses 19a and 19b.
Through the light-receiving element 43 of the distance measuring sensor 40, which is a light-receiving element.

Returning to FIG. 5, the photoelectric conversion output from the light receiving units 41, 42, and 43 by the distance measuring sensor 40 is output from the CPU.
20 is input.

Further, the distance measuring sensor 40 has a function of removing the stationary light, and removes the stationary light component, detects only the reflected light component from the subject by the projection, and performs the accumulation operation. I have.

The CPU 20 controls the light emission of the LED 10 via the LED driving circuit 11 and the ESHOE driving circuit 16
, The state of the ESHOEs 14 and 15 is controlled, and a distance measurement operation based on a photoelectric conversion output corresponding to the integration operation of the distance measurement sensor 40 is performed.

The principle of the distance measurement for the distance measurement operation is a well-known method based on triangulation and phase difference detection, and a description thereof will be omitted.

The CPU 20 includes a lens driving circuit 26 for driving the focusing lens 25, an EEPROM 27 which is a nonvolatile storage element in which various adjustment and correction data are written in advance, a zoom driving circuit 28 for driving the photographing lens 24, This switch is linked to the release button (not shown), and is the first release switch (1RSW)
29, the second release switch (2RSW) 30
Each is connected.

Then, as shown in FIG.
The four distance measuring areas are three distance measuring areas 21, 22, and 23.
It is assumed that

The focusing lens 25 of the photographing lens 24 is driven by a lens driving circuit 26 to perform focusing.

At this time, the CPU 20 controls the position of the focusing lens 25 via the lens driving circuit 26 based on the result of the distance measurement calculation.

The CPU 20 communicates with the EEPROM 27 to read out predetermined adjustment and correction data from the EEPROM 27 and use them for various correction calculations.

The zoom drive circuit 28 is provided by the CPU 2
The zoom system of the photographing lens 24 is driven based on the command of 0, and the focal length is detected and output to the CPU 20.

As described above, 1RSW 29 and 2RSW 30 are switches linked to the release button.
When pushed to the second stage, the 1RSW 29 is turned on, and when pushed to the second stage, the 2RSW 30 is turned on.

Next, the operation of the distance measuring apparatus having the above configuration will be described.

FIG. 8 shows the main flow of the CPU 20.

In step S11, the CPU 20
Performs electrical and mechanical initialization of each part of the camera.

In step S12, the CPU 20
If the 1RSW 29 is on, step S12
The process proceeds to step S19 if it is off.

At step S13, the CPU 20
Perform the distance measurement operation.

In step S14, the CPU 20
A photometric operation is performed by a photometric element and a photometric circuit (not shown).

In step S15, the CPU 20
When the 2RSW 30 is on, the process proceeds to step S16,
If it is off, the process returns to step S12.

At step S16, the CPU 20
The focusing lens 25 is driven based on the distance measurement result.

In step S17, the CPU 20
Exposure operation is performed.

In step S18, the CPU 20
The film (not shown) is wound up by one frame.

In step S19, CPU 20 determines
The input of operation switches (not shown) other than 1RSW29 and 2RSW30 is checked, and if there is an input from these operation switches, the process proceeds to step S20.

In step S20, the CPU 20
Processing corresponding to the input operation switch, for example, zooming of the photographing lens 24 is performed in response to operation of the zoom operation switch.

FIG. 9 shows a CPU according to the first embodiment.
2 shows a flowchart of a distance measuring operation by the reference numeral 20.

FIGS. 10A to 10G show timing charts of various parts in the distance measuring operation.

In step S101, when the CPU 20 starts the distance measuring sequence, the ESHOE driving circuit 16
As a result, ESHOEs 14 and 15 are initialized, and the applied voltage is turned on.

At this time, the ESHOEs 14 and 15 are in the transmission state (see FIGS. 10A and 10B).

In step S102, the CPU 20
Are supplied by the ESHOE driving circuit 16 to the ESHOE 14,
The applied voltage of No. 15 is turned off.

At this time, the ESHOEs 14 and 15 are in a diffraction grating state (see FIGS. 10A and 10B).

In step S103, the CPU 20
Starts the stationary light removal integration operation by the distance measurement sensor 40.

In step S104, the CPU 20
By controlling the LED drive circuit 11 to cause the LED 10 to emit light a plurality of times (see FIG. 10 (c)), three distance measurement areas 22, 23,
The projection light beams 31, 32, and 33 are projected on the light source 24.

At this time, each light receiving section 4 of the distance measuring sensor 40
The integration operations of 1, 42, and 43 are performed in synchronization with the light projection by the LED 10, and are controlled so that the integration amounts of the light receiving units 41, 42, and 43 are appropriate ((d) of FIG.
(E), (f)).

At the step S105, the CPU 20
Reads out sensor data, which is a photoelectric conversion result, from the light receiving units 41, 42, and 43 of the distance measuring sensor 40, performs a distance measuring operation, and obtains distance measuring data of the center distance measuring area 22, the left and right distance measuring areas 21, 23. In step S106, the CPU 20 selects one distance measurement data according to a predetermined algorithm using the distance measurement data of the three distance measurement areas 21, 22, and 23. To adopt.

In step S107, the CPU 20
Determines whether the center ranging area 23 has been selected.

Here, the CPU 20 determines that the central ranging area 2
When 3 is selected, in step S108,
The applied voltages of the ESHOEs 14 and 15 are turned on by the ESHOE drive circuit 16.

As a result, the ESHOEs 14 and 15 enter the transmission state (see FIGS. 10A and 10B).

In step S109, the CPU 20
Starts the stationary light removal integration operation of the light receiving unit 41 of the distance measurement sensor 40.

In step S110, CPU 20
Controls the LED drive circuit 11 to cause the LED 10 to emit light a plurality of times (see FIG. 10C), thereby projecting the projected light beam 32 to the distance measuring area 23 which is the central distance measuring area in the shooting screen 34. Light.

At this time, the integration operation of the light receiving section 41 of the distance measuring sensor 40 is performed in synchronization with the projection of the LED 10 (see FIG. 10E).

In step S111, the CPU 20
Reads out sensor data as an integration result of the light receiving unit 41 from the distance measurement sensor 40, performs distance measurement calculation, calculates distance measurement data of the central area 23, and sets it as final distance measurement data (see FIG. 10 (g)). .

On the other hand, when the area other than the center distance measurement area is selected in step S107, the CPU 20 adopts the distance measurement data as final distance measurement data, and proceeds to step S112.
Move to

In step S112, the CPU 20
Are connected to the ESHOEs 14 and 1 by the ESHOE drive circuit 16.
5 is turned on.

As a result, the ESHOEs 14 and 15 enter a transmission state.

As described above, the CPU 20 first sets the ES
HOEs 14 and 15 function as diffractive optical elements,
The total luminous flux of D10 is divided into three and projected onto three distance measurement areas to perform three-point distance measurement.

When the central ranging area is selected by the three-point ranging, the CPU 20 sets the ESHOE 1
Since the distances 4 and 15 are set to the transmitting state and the total luminous flux of the LED 10 is projected to the central distance measuring area 23 where the probability of the existence of the main subject is very high, distance measurement is performed.

In the above embodiment, an LED is used as the light emitting element, but a light source other than the LED may be used.

For example, if a light source such as a krypton lamp, a Xe tube of a strobe device, a laser, or the like, which emits a large amount of light is used, it is possible to measure the distance to a greater distance.

It should be noted that instead of the light projecting lens 12, an ESHO
The projection lens 12 may be omitted by giving E14 and E15 a convex lens characteristic.

As described above, by projecting light corresponding to a plurality of ranging areas by using an electrically switchable diffractive optical element in the light projecting section, it is possible to reduce the number of component parts in a small size. In addition to this, it is possible to perform more accurate AF ranging in the central ranging area.

(Second Embodiment) Next, a description will be given of a second embodiment in which the distance measuring apparatus of the present invention is specifically applied to a camera.

FIG. 11 shows, as a second embodiment in which the distance measuring apparatus of the present invention is specifically applied to a camera, a camera equipped with an active distance measuring apparatus for measuring three points in a shooting screen. 3 is a block diagram showing a configuration of a main part for improving the accuracy of the left and right distance measurement areas.

That is, in the first embodiment, the accuracy is improved only in the distance measurement of the center distance measurement area 22 in the distance measurement area 34 shown in FIG. 7, but in the second embodiment. In the embodiment, the accuracy of the left and right distance measurement areas other than the center distance measurement area 22 is improved.

For example, three distance measuring areas (21 in FIG. 7,
22 and 23), when increasing the accuracy of each ranging area, as shown in FIGS. 11A, 11B and 11C, the first area shown in FIG. E according to the embodiment of
In addition to the SHOEs 14 and 15 and the transparent portion 13 thereon, ESs having different diffraction angles corresponding to the projection angles
Two more HOEs 106 and 107 are arranged so as to overlap each other.

Then, the ESHOEs 106 and 107 having different diffraction angles corresponding to such light projection angles are converted into ESHEs 106 and 107.
The OE drive circuit 16 turns off the applied voltage of one ESHOE in a time-sharing manner and emits light in a diffraction grating state, so that the left and right distance measurement areas 21 other than the center distance measurement area 22 can be used.
23 can also be improved in accuracy.

FIG. 12 shows a CP according to the second embodiment.
9 shows a flowchart of a distance measuring operation by U20.

FIGS. 13A to 13I show timing charts of various parts in this distance measuring operation.

Note that (A), (B), and (C) in FIG.
Is selected and executed.

In step S201, the CPU 20
Turns on the applied voltage to the ESHOEs 14, 15, 106, and 107 to make the ESHOEs 14, 15, 106, and 107 transparent and initializes them.

In step S202, the CPU 20
Turns on the applied voltage of ESHOEs 106 and 107 to
The SHOEs 106 and 107 are set in a transmission state, and the ESHOE 1
The applied voltages 4 and 15 are turned off to bring the ESHOEs 14 and 15 into a diffraction grating state.

Steps S203 to S206 are the same as S101 to S106 of the first embodiment, and a description thereof will be omitted.

At step S207, the CPU 20
Determines whether the center ranging area 22 has been selected.

Here, the CPU 20 determines that the central ranging area 2
When 2 is selected, the applied voltage of the ESHOEs 14, 15, 106, and 107 is turned on by the ESHOE drive circuit 16.

As a result, ESHOE 14, 15, 10
Reference numerals 6 and 107 are in a transmission state (see FIG. 13A).

In step S209, the CPU 20
Starts the stationary light removal integration operation of the light receiving unit 41 of the distance measurement sensor 40.

In step S210, the CPU 20
Controls the LED driving circuit 11 to cause the LED 10 to emit light a plurality of times, thereby projecting the projected light beam 32 to the distance measuring area 22 which is the central distance measuring area in the photographing screen 34.

At this time, the integration operation of the light receiving section 41 of the distance measuring sensor 40 is performed in synchronization with the projection of the LED 10.

Next, in step S211, the CPU 20 reads out sensor data, which is the result of integration of the light receiving section 41, from the distance measuring sensor 40, and in step S212,
Distance measurement calculation is performed to calculate distance measurement data of the central area 23, which is used as final distance measurement data.

In step S213, the CPU 20
Turns on the voltage applied to the ESHOEs 14, 15, 106, and 107 to make the ESHOEs 14, 15, 106, and 107 transparent, and then returns.

On the other hand, if an area other than the central ranging area is selected in step S207, the CPU 20 proceeds to step S207.
Move to 214.

At the step S214, the CPU 20
Determines whether the left ranging area 21 has been selected.

If the left distance measuring area 21 is selected, the CPU 20 determines in step S214 that E is
Turn on the applied voltage of SHOE 14, 15, 107 and
The HOEs 14, 15, and 107 are set in the transmission state, and the ESHOE
The applied voltage at 106 is turned off to bring the ESHOE 106 into a diffraction grating state (see FIG. 13C).

In step S216, the CPU 20
Starts the stationary light removal integration operation of the light receiving unit 42 of the distance measurement sensor 40.

At step S217, the CPU 20
Controls the LED drive circuit 11 to cause the LED 10 to emit light a plurality of times, thereby projecting the projected light beam 31 to the left distance measurement area 21 in the shooting screen 34.

At this time, the integration operation of the light receiving section 42 of the distance measuring sensor 40 is performed in synchronization with the projection of the LED 10.

Next, in step S218, the CPU 20 reads out sensor data as an integration result of the light receiving section 42 from the distance measuring sensor 40, and in step S219,
Distance calculation is performed to calculate distance measurement data of the left distance measurement area 21 to be final distance measurement data.

On the other hand, in step S214, the left distance measurement area 2
If No. 1 has not been selected, that is, if the right distance measurement area 24 has been selected, the CPU 20 proceeds to step S
Proceed to 220.

At the step S220, the CPU 20
Indicates that when the right ranging area 23 is selected, the ESHO
Turn on the applied voltages of E14, 15, and 107 to set ESHOE
14, 15, and 107 are in a transmission state, and ESHOE 107 is
Is turned off to bring the ESHOE 107 into a diffraction grating state (see FIG. 13B).

At the step S221, the CPU 20
Starts the stationary light removal integration operation of the light receiving unit 43 of the distance measurement sensor 40.

At the step S222, the CPU 20
Controls the LED drive circuit 11 to cause the LED 10 to emit light a plurality of times, and to project the projected light beam 31 to the right distance measurement area 23 in the shooting screen 34.

At this time, the integration operation of the light receiving section 43 of the distance measuring sensor 40 is performed in synchronization with the projection of the LED 10.

Next, in step S 223, the CPU 20 performs sensor data reading distance measurement calculation as the result of integration of the light receiving section 43 of the distance measurement sensor 40, and proceeds to step S 22.
In 4, the distance measurement data of the right distance measurement area 22 is calculated to be final distance measurement data.

The CPU 20 determines in steps S219 and S2
After 24, return.

As described above, in the distance measuring apparatus according to the second embodiment, not only when the center ranging area 22 is selected by the three-point ranging but also when the left and right ranging areas 21 and 23 are selected. In ESHOE14, 15 and 10
Since the distances are measured by controlling the light beams 6 and 107 to project the entire luminous flux of the LED 10 to a desired distance measurement area, more accurate distance measurement can be performed.

FIG. 14 is a diagram showing another configuration for improving the accuracy of the left and right distance measurement areas as a modification of the second embodiment.

In this modification, as a configuration for improving the accuracy of the left and right distance measurement areas, in addition to the ESHOEs 14 and 15 and the transparent portion 13, the corresponding divided Es
Glass substrates 108 having SHOEs 109 and 110 are stacked and arranged.

Here, when the ESHOEs 109 and 110 function as diffractive optical elements, the diffractive optical characteristics are recorded so that the projected light beam of the LED 10 is diffracted so as to coincide with the light beams 31 and 33, respectively.

When performing high-precision distance measurement in the left and right distance measurement areas, the ESHOEs 14 and 15 are projected in a transmissive state (voltage applied), and the ESHOEs 109 and 110 are projected in a diffraction grating state (no voltage applied) to emit light. Do the distance.

As described above, according to the second embodiment, a plurality of diffractive optical elements that can be electrically switched at different diffraction angles are arranged one on top of the other, and each is independently in a diffraction grating state, By performing the control for setting the lattice state, it is possible to perform highly accurate ranging for a desired ranging area.

(Third Embodiment) FIG. 15 shows, as a third embodiment of the present invention in which a reflection type ESHOE is used, an active distance measuring device for measuring three points in a photographing screen. FIG. 2 is a diagram showing a configuration of a main part in a camera equipped with a camera.

In the first and second embodiments, the distance measuring apparatus using the transmission type ESHOE has been described.
In the third embodiment, different portions of the distance measuring apparatus using the reflection type ESHOE will be described.

That is, FIG. 15 shows the configuration of a light emitting and receiving unit when applied to an active distance measuring device that measures distances at three points in a photographing screen.

Light emitting diode (LED) as a light emitting element
Reference numeral 10 is arranged at the focal position of the concave mirror 113 and is connected to the LED drive circuit 11.

The light beam emitted from the LED 10 is divided into a concave mirror 113 and a plurality of divided reflective ESHOEs 114.
The light beams 131, 132, and 13 reflected by 115
The light is projected on the subject as 3.

In the reflection type ESHOEs 114 and 115, characteristics as a reflection element having concave mirror characteristics are formed in advance.

The reflection type ESHOEs 114 and 115
Under the control of the HOE drive circuit 16, when a control voltage is applied, a transmission state is set, and when no control voltage is applied, a reflection element state is set.

Therefore, when the reflective ESHOE 114 functions as a reflective element, it reflects the projected light beam from the LED 10 as the projected light beam 132.

Similarly, when the reflection type ESHOE 115 functions as a reflection element, it reflects the light beam emitted from the LED 10 as the light beam 133.

The concave mirror 113 reflects the light beam emitted from the LED 10 as a light beam 131.

As described above, the reflection type ESHOEs 114 and 11
5 are independently controlled on and off to control the light projection angle.

The reflected light from the subject by the projected light beam 131 is reflected by the light receiving lens 1 as shown in FIG.
The light enters the light receiving unit 41 of the distance measuring sensor 40 as a light receiving element via 7a and 17b.

Similarly, the light reflected from the subject by the projected light beam 132 is reflected by the light receiving lens 1 as shown in FIG.
The light enters the light receiving unit 42 of the distance measuring sensor 40 as a light receiving element via 8a and 18b.

Similarly, the projected light beam 133 is
The reflected light from the subject enters the light receiving section 43 of the distance measuring sensor 40 as a light receiving element via the light receiving lenses 19a and 19b as shown in FIG.

The light receiving sections 41, 42,.
The photoelectric conversion output of 43 is input to the CPU 20.

The CPU 20 controls the light emission of the LED 10 via the LED drive circuit 11, controls the state of the ESHOEs 114 and 115 via the ESHOE drive circuit 16, and performs measurement based on the photoelectric conversion output according to the integration operation of the distance measurement sensor 40. Perform distance calculation.

As shown in FIG. 7, the three distance measuring areas 21, 22, and 23 in the photographing screen are shown.

In the configuration of the light emitting and receiving unit according to the third embodiment as described above, control in which diffraction is replaced by reflection is executed based on the distance measurement flow shown in FIG. 16 corresponding to the first embodiment. By projecting light corresponding to a plurality of ranging areas, it is possible to reduce the number of component parts in a small size, and to perform more accurate AF ranging in the central ranging area. it can.

The distance measuring flow shown in FIG. 16 is different from the distance measuring flow shown in FIG.
9 except that SHOE 114 and 115 are replaced.
Are the same as steps S101 to S113 of the distance measurement flow shown in FIG.

Also, in the third embodiment, FIG.
As shown in FIG. 1, the reflection type ESHOEs 108 and 109 having reflection angles corresponding to the left and right distance measurement areas are further superimposed and arranged, and the same control as in the second embodiment is performed. Also, the distance measurement for high-precision AF can be performed similarly to the center distance measurement area.

When such a distance measuring device is arranged in a small device such as a camera, efficient layout is achieved by selecting a transmission type ESHOE and a reflection type ESHOE in accordance with an allowable space. Miniaturization is possible.

(Fourth Embodiment) FIG. 17 shows a configuration in which the present invention is applied to a single-lens reflex camera as a fourth embodiment.

In FIG. 17, reference numeral 201 denotes a camera body, 202 denotes a lens barrel for holding a photographing lens 203 so as to be movable in the optical axis direction, and 204 denotes a movable half for dividing subject light into a distance measuring system and a finder system. A mirror 205, a pentaprism, a focus plate 206 that forms a finder system together with the eyepiece 207, a movable mirror 208 for guiding a light beam to the focus detection device 209, and a distance measuring device 210 described later in the fourth embodiment. Auxiliary light device.

FIG. 18 shows the focus detecting device 2 in FIG.
FIG. 9 is a perspective view showing a specific configuration of the embodiment 09.

That is, in FIG.
Reference numeral 1 denotes a field mask, which has a rectangular opening 30 corresponding to the focus detection area.
1-1, 301-2, 301-3, and a photographing lens 2
03 is arranged near the planned imaging plane.

Reference numeral 302 denotes a field lens, which has a plurality of field lens units 302-1, 302-2, and 302-3 corresponding to the focus detection areas.

Reference numeral 303 denotes a pupil mask.
A pair of pupil mask openings 3 respectively corresponding to the focus detection areas
03-1a, 303-1b and 303-2a, 303-2
b and 303-3a and 303-3b.

Reference numeral 304 denotes a re-imaging lens, and a pair of re-imaging lenses 304-1a, 304-1b and 304-2a, 304-2 corresponding to the focus detection areas, respectively.
-2b, 304-3a, and 304-3b.

Reference numeral 305 denotes an AF sensor, which is a pair of photoelectric conversion element arrays 305-1a and 305-1b.
305-2a, 305-2b and 305-3a, 305
-3b.

Reference numeral 306 denotes the photographing lens 203.
The focus detection is performed by the light flux passing through 306a and 306b.

Each rectangular opening 301-
The light beams that have passed through 1, 301-2, and 301-3 pass through the corresponding field lens units 302-1, 302-2, and 302-3 of the plurality of field lens units 302.

Further, a pair of corresponding pupil mask openings 303-1a, 303-1b and 303-2a, 303
-2b, 303-3a, and 303-3b respectively pass through the pair of re-imaging lenses 304-1a, 304-1b, 304-2a, and 304- of the re-imaging lens unit 304.
2b, 304-3a, and 304-3b, a pair of photoelectric conversion element arrays 305-1a,
305-1b and 305-2a, 305-2b and 305-
An object image is formed on 3a, 305-3b.

In this case, the interval between the two divided object images relatively changes according to the position of the formed object image with respect to the predetermined image forming plane, that is, the defocus state of the photographing lens 203.

The pair of photoelectric conversion element rows 305-1a,
305-1b and 305-2a, 305-2b and 305-
In 3a and 305-3b, the relative intervals of the light quantity distribution are detected using the result (sensor data) of converting the object image into an electric signal.

As described above, focus detection is performed on a plurality of (three) focus detection areas to detect a focus state.

FIG. 19 shows focus detection areas 321, 322, and 323 in the photographing screen 324.

The block configuration of the fourth embodiment is the same as the block configuration of the first embodiment shown in FIG.

FIG. 20 is a diagram showing the structure of the auxiliary light device 210. As shown in FIG.

Light emitting diode (LED) as light emitting element
310 is connected to the LED drive circuit 311 and this LE
The projected light beam from D310 passes through a pattern film 335, which will be described later, and passes through a projected lens 312 and a plurality of divided ESHOEs 314 and 315 or a transparent portion 333-1.
313-2, the projected light flux 331, 33
Light is emitted as 2,333.

FIG. 21 is a view showing a specific example of the pattern film 335.

That is, the pattern film 335 shown in FIG. 21 has a pattern portion 336 in which stripe-shaped light transmitting portions and non-transmitting portions are alternately arranged.

The ESHOEs 314 and 315 are ESHOEs.
The driving circuit 316 is connected to the ESH0E 314, 315
The diffraction angle is controlled on / off to control the projection angle.

When functioning as a diffractive optical element, the ESHOE 314 diffracts the projected light beam from the LED 310 as a projected light beam 331.

Similarly, when functioning as a diffractive optical element, the ESHOE 315 diffracts the light beam emitted from the LED 310 as a light beam 333.

The main luminous flux due to the projected luminous flux of the LED 310 passing through the transparent portions 313-1 and 313-2 is 332.
Becomes

FIG. 22A shows ESHOEs 314, 3
When the LED 15 functions as a diffractive optical element, the LED 3
The pattern unit 336 is projected on the object to be measured by distance from the light beam emitted from the light source 10 (pattern image) 337, 338,
339 are shown.

Here, the pattern image 337 is the ESHOE
It is formed by the projected light beam diffracted by 314.

Similarly, the pattern image 339 is the ESHOE
It is formed by the projected light beam diffracted by 315.

Further, the pattern image 338 is formed on the transparent portion 31.
3-1 and 313-2 are formed by the projected light beam.

FIG. 22B shows ESHOEs 314, 3
15 is set to a transmissive state without functioning as a diffractive optical element, the pattern portion 336 is projected by a light beam emitted from the LED 310 onto the pattern-measuring object.
38 is shown.

At this time, as shown in FIG.
The pattern image 338 (b) of FIG. 22B has higher illuminance and contrast than the pattern image 338 (a) of FIG. Focus detection at a long distance can be performed.

FIG. 22D shows a photographing screen in the case of a photographing lens having a large focal length. At this time, the left and right projected light beams are out of the photographing screen.

In such a case, ESHOE 314, 3
Even if 15 functions as a diffractive optical element, the pattern image 33
7, 339 are invalid.

Therefore, by transmitting the diffractive optical elements 314 and 315 in accordance with the focal length of the photographing lens, the pattern images 337 and 339 are not projected, and the pattern images 338 and 339 are not projected.
Only light can be emitted to prevent waste.

As described above, by using an electrically switchable diffractive optical element in the light projecting unit and switching its characteristics, light is projected to a plurality of focus detecting areas and a specific focus detecting area, for example, a frequently used one. By switching between light projection for the central region, it is possible to reduce the number of component parts in a small size and to perform more accurate AF.

[0209]

Therefore, as described above, according to the present invention, it is possible to provide a distance measuring apparatus which can be reduced in cost and size and can perform high-performance distance measuring. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a conceptual configuration of a distance measuring apparatus according to the present invention.

FIG. 2 is a diagram for explaining a diffraction phenomenon occurring in a general diffractive optical element (DOE).

FIG. 3 is a diagram illustrating a general diffractive optical element (DOE) that, when focusing on one diffraction order, continuously changes a pitch d of a diffraction grating to condense an m-order diffracted light beam. It is a figure which shows that it can give the effect | action of a lens etc.

FIG. 4 is a view for explaining a method of producing a transmission type diffractive optical element ESHOE as an electrically switchable diffractive optical element without using a mechanical mechanism used in the present invention, and an operation principle thereof. FIG.

FIG. 5 shows a first embodiment in which the distance measuring apparatus of the present invention is specifically applied to a camera, in which an active distance measuring apparatus for measuring distances at three points in a shooting screen is mounted. FIG. 2 is a block diagram illustrating a configuration of a camera.

FIG. 6 is a diagram illustrating a specific example of each unit illustrated in FIG. 5;

FIG. 7 shows an example of a distance measurement area of 34 in the photographing screen.
FIG. 3 is a diagram showing distance measuring areas 21, 22, and 23;

FIG. 8 is a diagram showing a main flow of the CPU 20.

FIG. 9 is a diagram illustrating a CPU 20 according to the first embodiment;
5 is a flowchart of a distance measuring operation according to the first embodiment.

FIG. 10 is a timing chart of each unit in a distance measuring operation according to the first embodiment.

FIG. 11 shows a second embodiment in which the distance measuring apparatus of the present invention is specifically applied to a camera, in which an active distance measuring apparatus for measuring three points in a shooting screen is mounted. FIG. 3 is a block diagram showing a configuration of a main part of the camera for improving the accuracy of a left and right distance measurement area.

FIG. 12 is a diagram illustrating a CPU according to a second embodiment;
4 is a flowchart of a distance measurement operation performed by No. 20;

FIG. 13 shows a timing chart of each unit in a distance measuring operation according to the second embodiment.

FIG. 14 is a diagram showing another configuration for improving the accuracy of the left and right distance measurement areas as a modification of the second embodiment.

FIG. 15 is a main part of a camera equipped with an active distance measuring device for measuring three points in a shooting screen as a third embodiment according to the present invention using a reflective ESHOE; FIG. 3 is a diagram showing the configuration of FIG.

FIG. 16 is a diagram illustrating a CPU according to a third embodiment;
4 is a flowchart of a distance measurement operation performed by No. 20;

FIG. 17 is a diagram showing a configuration in a case where the present invention is applied to a single-lens reflex camera as a fourth embodiment.

FIG. 18 is a diagram illustrating the focus detection device 20 shown in FIG.
9 is a perspective view showing a specific configuration of No. 9; FIG.

FIG. 19 shows focus detection areas 321, 322, and 323 in the photographing screen 324.

FIG. 20 is a diagram showing a configuration of the auxiliary light device 210.

FIG. 21 is a diagram showing a specific example of the pattern film 335.

FIG. 22 is a diagram for explaining an operation according to the fourth embodiment;

[Explanation of symbols]

Reference numeral 1 denotes a light projecting unit having a light projecting unit; 2 ... a light receiving unit having a light receiving unit for receiving reflected light from a subject; 3a, 3b, 3c ... a light emitting unit from the light projecting unit 1 can be electrically switched. A plurality of diffractive optical elements, 4 a control unit for performing a distance measurement calculation to the subject based on an output from the light receiving unit 2, 10 a light emitting diode (LED), 12 a light projecting lens 12, 14. , 15: ESHOE, 13: Transparent part on top of ESHOE 14, 15, 32, 33, 31: Projected light flux, 120, 121: Glass substrate, 16: ESHOE drive circuit, 83, 84: AC power supply, 81, 82 ... Electrical switch element, 20 ... Microcomputer (CPU), 17a, 17b, 18a, 18b, 19a, 19b ... Light receiving lens, 40 ... Distance sensor, 41,42,43 ... Light receiving 11: LED drive circuit, 25: focusing lens, 26: lens drive circuit, 27: EEPROM, 24: photographing lens, 28: zoom drive circuit, 29: first release switch (1RSW), 30: second release switch (2RSW) ), 21, 22, 23: ranging area, 106, 107: ESHOE, 108: glass substrate, 109, 110: ESHOE, 113: concave mirror, 114, 115: reflective ESHOE, 131, 132, 133: light projection 201: camera body, 202: lens barrel, 203: photographing lens, 204: half mirror, 205: pentaprism, 206: focus plate, 207: eyepiece, 208: movable mirror, 209: focus detecting device, 210 ... Auxiliary light device for ranging, 301 ... Field of view .., Rectangular apertures corresponding to the focus detection areas, 302... Field lenses, 302-1, 302-2, 302-3. , 303-1a, 303-1b, 303-2a, 303-
2b, 303-3a, 303-3b: A pair of pupil mask apertures, 304: Re-imaging lens, 304-1a, 304-1b, 304-2a, 304-
2b, 304-3a, 304-3b ... a pair of re-imaging lenses, 305 ... AF sensor, 305-1a, 305-1b, 305-2a, 305-
2b, 305-3a, 305-3b... A pair of photoelectric conversion element rows, 306... A photographing lens, 306a, 306b. 321, 322, 323: Focus detection area, 310: Light emitting diode (LED) as a light emitting element, 311: LED drive circuit, 335: Pattern film, 312: Light emitting lens 314, 315: ESHOE divided into a plurality, 333 -1, 313-2: transparent portion; 331, 332, 333: light beam, 336: pattern portion in which stripe-shaped light transmitting portions and non-transmitting portions are alternately arranged.

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Claims (4)

[Claims] 1. A light projecting means for projecting distance measuring light, a light dividing means for dividing and projecting the distance measuring light in a plurality of directions, and a light beam divided and projected via the light dividing means. A light-receiving means for receiving reflected light of the distance-measuring light from the distance-measuring object; and a detecting means for detecting the distance of the distance-measuring object based on an output of the light-receiving means. The distance measuring device is characterized in that the light dividing means is an electrically controllable divided diffraction or reflection optical element. 2. The diffractive or reflective optical element divided into a plurality of parts can be independently controlled so as to selectively project the distance measuring light to a predetermined light projecting area. The distance measuring device according to claim 1. 3. The light splitting means comprises a stack of a plurality of the diffractive or reflective optical elements, and electrically controls each of the diffractive or reflective optical elements so that the distance measuring light is applied to a predetermined area. The distance measuring device according to claim 1, wherein light can be selectively projected. 4. The distance measuring apparatus according to claim 1, wherein the diffraction or reflection optical element inputs an electric signal to a diffraction grating formed of a polymer liquid crystal and eliminates the electric signal.