JPH0371104A - Range finder - Google Patents

Abstract

PURPOSE:To effectively utilize an image pickup element for electronically picking up an object image and to highly accurately measure a range from an object by projecting spot light in the direction of the object to be picked up through an image pickup optical system lens on a position separated from the lens by a prescribed base length and detecting its reflected light image by the image pickup element. CONSTITUTION:The projection part 4 for projecting spot light to the object to be picked up through the image pickup optical system lens 1 is arranged on the position separated from the lens 1 by the prescribed base length (d). The projection part 4 consists of a light emitter 4a and a projection lens 4b for projecting light emitted from the light emitter 4a to the object as spot light and is driven by a projection part driver 5 to project the spot light to the object. The reflected light of the spot light which is reflected by the object is photodetected by the image pickup element 2 through the lens 1 and its picked-up signal is inputted to a system controller 6 through an illuminance detecting part 9 to calculate a range from the lens 1 up to the object.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention effectively utilizes the imaging element [C] which images a subject image through the imaging optical system lens. The present invention relates to a distance measuring device that measures a distance f4 to an object (an object photographing distance necessary for including a black spot on an imaging optical system lens).

[Conventional techniques] In recent years, the control technology of automatic black point alignment (AF, autofocusing) for the subject of the imaging optical system lens has been remarkable, and it has been applied not only to still cameras using silver halide film but also to image sensors. Many cameras have come to be incorporated into video movie cameras that electronically capture images of subjects.

This type of AF sub-control basically measures the distance from the imaging optical system lens to the subject (subject shooting distance) optically, for example, according to the principle of triangulation, and then uses the imaging optical system according to information on this measured subject distance. This is for adjusting the focus of the lens system on the subject. However, the 1illll IiU power method for performing AF sub-control can be roughly divided into active methods and passive methods.

The active method is a method of actively determining the total distance to the subject using an auxiliary means of infrared light, and is often used as an AF control means in, for example, so-called compact cameras. This method uses a pair of light projecting section and light receiving section that are provided at the camera position with a predetermined prefectural line length apart, and projects infrared light from the light projecting section toward the subject.

Then, the reflected light of the infrared light projected onto the subject is detected by the light receiving section, and the receiving position of the reflected light on the light receiving section is frozen. However, since the light receiving position of the reflected light on the light receiving part of the lever is displaced in the direction of the base line according to the distance to the subject, information on the light receiving detection position of the reflected light and the light emitting part and the light receiving part are The distance to the subject is measured according to the principle of the two-angle 1fll+quantization method according to the distance to the object (predetermined base line length).

However, in this active method, - For boat fishing, the light emitting part and the light receiving part are provided separately from the imaging optical system.
Camera design is likely to be restricted in terms of where these light projecting sections and light receiving sections are provided. Moreover, due to various restrictions on a general line sensor used as a light receiving section, there is a limit to its full+range performance and high performance.

On the other hand, the passive method basically measures the object distance by utilizing the fact that the correlation between the object images detected by different optical systems changes depending on the object distance. Flex camera': This is often used in 9-inch cameras. In this method, for example, a plurality of distance measuring optical systems are configured to respectively detect the subject image through a position off the center of the imaging optical system lens, and each of these distance measuring optical systems detects the object image. Correlation of subject images,
For example, this is realized by measuring the object distance from the phase difference (shift) of the point of interest. Also, in conjunction with the AF control system,
The lens of the imaging optical system is moved forward and backward so that the lens of the imaging optical system is adjusted so as to eliminate the phase shift between the subject images detected by each of the distance measuring optical systems.

However, in the above-mentioned passive method, depending on the nature of the subject, it is often difficult to detect the correlation between the subject images, specifically, the phase shift between the images. In particular, when the subject brightness is low and the subject image is distorted, it becomes difficult to detect the subject image itself with high sensitivity, which causes problems such as it becomes extremely difficult to find the correlation between the subject images. be. Moreover, for boat fishing, it is necessary to configure multiple ranging optical systems to detect each object image through a position off the center of the imaging optical system lens, which makes the optical system complicated. I can't deny it.

Incidentally, recently, electronic still images have been developed in which a subject image is electronically captured using a solid-state image sensor such as a CCD, the electronic still image is recorded on a recording medium such as a floppy disk, and the image is reproduced using a TV receiver or the like. Cameras are attracting attention. However, when incorporating an AF control mechanism into this type of electronic still camera, since it is equipped with a high-resolution light-receiving section, such as the solid-state image sensor mentioned above, it is used as the above-mentioned distance measuring element, and an active method is used. Alternatively, it is possible to realize a passive distance measuring device.

In order to measure the object distance by using a solid-state imaging probe for imaging a subject as a light-receiving section for 11Pj distance, for example, an imaging optical system is required to form an object image on the light-receiving surface of a solid-state image sensor. Since the distance measurement conditions change depending on the optical state (properties) of the lens, there are still several issues that need to be resolved. For example, when trying to realize a passive distance measuring device using the above-mentioned solid-state imaging probe, how should the imaging area of the solid-state imaging probe be divided into multiple regions, and what should be done for each of these divided regions? There arises an optical problem of how to form the respective subject images. Moreover, there is also the problem of how to incorporate such an optical system into the imaging optical system.

Furthermore, when attempting to realize an active distance measuring device using the above-mentioned solid-state image sensor, the imaging position of the light reflected by the subject on the imaging surface depends on the settings of the imaging optical system lens (focusing position, zoom magnification, etc.). Since the distance and the amount of deviation thereof are greatly reduced, there is a problem of how to correct this and obtain the subject distance accurately. Moreover, since the imaging surface area is large, not only the distance measuring light reflected by the subject, but also the light components of the subject and its surroundings are captured and input into the image sensor, so how can these noise components be eliminated? There also remains the question of whether accurate distance measurement can be performed.

[Problems to be Solved by the Invention] In an electronic still camera that electronically images a subject using an image sensor as described above, when attempting to realize a distance measuring device that measures the distance to a subject using the image sensor. For example, there are problems such as the sub-conditions changing significantly depending on the optical condition of the imaging optical system lens for forming a subject image etc. on the imaging surface of this imaging device, and how can this be overcome? There are some issues that remain.

The present invention has been made in consideration of these circumstances, and its purpose is to determine the subject distance with high accuracy m11 by effectively utilizing an image sensor that electronically captures the subject image. The objective is to provide a highly practical zero distance measuring device that can be used to

[Means for Resolving the Problem] The 1illll k'li device according to the present invention is arranged at a position separated by a predetermined baseline length from the imaging optical system lens for forming a subject image on the imaging surface of the imaging element. , a step section is provided for projecting a spot light toward a subject to be imaged through the imaging optical system 1 lens and making the reflected light enter the imaging element through the imaging optical system lens. The imaging optical system lens is positioned at a predetermined focal position prior to the imaging operation of the subject by the imaging element, and the imaging optical system lens is thus positioned at a predetermined sunspot position. The imaging device detects a reflected light image of the spot light I/j projected from the projection part through the object. Then, the imaging position of the spot light image on the imaging surface of the imaging element is determined, and the separation distance from the imaging optical system lens to the subject is calculated based on the information on the imaging position of the spot light image. It is characterized by the following.

1] Specifically, for example, information on at least two photographing distances that are known in advance, and information on the imaging position on the imaging surface of the spot light reflected by the subject at each of these photographing distances are stored respectively. Then, based on these stored information and the information on the imaging position of the spot light image on the imaging mountain where the shooting MIif4 is distorted by the unknown object, the shooting distance of the object is set to 4! The feature is that the distance is calculated according to the principle <I of lj quantity note.

Furthermore, if the imaging optical system lens is of a type with a variable imaging magnification, that is, a so-called zoom lens, the imaging optical system lens is set to a predetermined imaging magnification prior to the imaging operation of the subject by the imaging device. The invention is characterized in that the above-mentioned subject distance is adjusted to the mouth side, and after that, the photographing magnification is returned to the original value, and then the focus adjustment as described in sentence 1 is performed on the subject of the imaging optical system lens. It is something.

Furthermore, when determining the imaging position of the reflected light image of the subject of the spot light, the optical image determined from the image pickup device when the spot light is irradiated and the light image determined from the image pickup device when the spot light is not irradiated are determined. The noise component is eliminated by finding the difference component from the optical image that is generated.
Furthermore, if the level of the difference component of the optical image is equal to or less than a predetermined threshold value t(
When the camera is not in use, the imaging time of the light image by the spot light beam is reset to a longer time to determine the difference component of the light image, and then the imaging position of the spot light is determined. .

[Function] According to the present device configured as described above, after setting the imaging optical system lens to a predetermined optical condition, the projection lens provided at a position separated from the imaging optical system lens by a predetermined baseline length is set. Since the reflected light image of the spot light projected from the shaving part towards the subject is received and detected by the image sensor through the imaging optical system lens, the light reflected by the subject is formed on the light receiving surface of the image sensor. It becomes possible to find a predetermined relationship between the image position and the subject distance, and it becomes possible to measure the subject distance by using the image sensor for photographing the subject for rightward movement.

In addition, at least two objects whose distances are known] 3. Information on the image formation position on the light receiving surface of the reflected spot light image from the subject, and the reflected spot light image from the subject to be measured whose subject distance is unknown. Since the distance to the object is calculated according to the information on the image forming position in the upper grasp light and the second step, it is possible to measure the distance to the object very simply and with high precision. Moreover, by adopting such a calculation method, it is possible to calculate the subject distance with good viscosity even when the calculation conditions (shooting magnification, etc.) are changed depending on the optical properties of the imaging optical system lens. becomes.

Furthermore, according to the present invention, a spot light is applied to the subject,
! 1. Since the imaging position of the spot light is detected by calculating the difference component between the light image of the subject when t L, and the light image of the subject when no spotlight is projected, unnecessary light components from the subject can be effectively removed. Only the spot light component that is removed and used for measuring the object distance can be accurately received and detected, and the imaging position on the light-receiving surface 2 can be accurately determined. Furthermore, when the level of the difference component is low, the imaging level of the subject light image is increased by increasing the imaging time, thereby ensuring that the spot light image represented by the difference component] 4 is detected. , it becomes possible to measure the object distance with sufficiently high detection accuracy.

[Example] Hereinafter, an ill distance device according to an example of the present invention will be described with reference to the drawings.

The distance measuring device according to the present invention is incorporated into an electronic still camera that electronically images a subject using an image sensor such as a CCD, and the image sensor is used as a light receiving section for distance measurement. It is realized using

FIG. 1 is a diagram showing a schematic configuration of a distance measuring device according to an embodiment,
1 is an optical system lens for imaging. This imaging optical system lens 1 forms a subject image onto the imaging surface of an image sensor (imager) 2, and includes a focusing lens system (F system) for adjusting the focus on the subject and a variable magnification for photographing the subject. It is equipped with a zooming lens system (Z system) for

The electronic still camera drives the imaging optical system lens 1 with a lens drive unit 3 to perform 5-focusing on the subject, and then focuses the image onto the light-receiving surface of the image sensor 2 via the imaging optical system lens 1. An image of a subject is electronically captured by an image sensor 2 to obtain an electronic still image signal. The electronic still image signal obtained by the image sensor 2 in this manner is guided to a video signal processing section (not shown) of the camera system, undergoes predetermined signal processing, and is recorded on a floppy disk or the like.

At a position separated by a predetermined baseline length d from the imaging optical system lens 1, there is a projection unit that projects a spot light onto a subject (not shown) to be imaged via the imaging optical system lens 1. 4 is provided. This projection section 4 is
For example, a light emitter 4a and a projection lens 4b that projects the light emitted from the light emitter 4a onto a subject as spot light.
It is driven by a projection unit driver 5 to project the spot light toward the subject. The projection direction of this spot light is determined by the imaging optical system lens I as described later.
It is tilted at a predetermined angle θ with respect to the direction of the optical center axis of the lens, and is defined as a direction that intersects the optical center axis.

For example, the system controller 6 mainly composed of a CPtJ operates in response to instructions from an operation unit 7 equipped with a shirt release switch etc. The lens driving section 3 is activated according to the target state to set the optical state of the imaging optical system lens 1 to a predetermined state.

Specifically, as will be described later, the zooming lens system (system 2) is driven to set the imaging magnification of the imaging optical system lens l to a predetermined magnification according to the optical properties of that lens, and the focusing The lens system (F system) is driven to set the focal position of the imaging optical system lens 1 to a predetermined position.

After setting the optical conditions of the imaging optical system lens l to a predetermined state in this way, the system controller 6 activates the projection unit driver 5 to project a spot light toward the subject.

Then, the reflected light reflected by the object of this spot light is received and detected by the image sensor 7 through the imaging optical system lens 1, and the image signal is sent to the inside of the system controller 6 via the illuminance detection section 9. I'm taking it in.

The system controller 6 determines the light reception detection position of the spot light on the imaging surface of the image sensor l from the reflected light image of the spot light detected by the subject, and according to the information stored in advance in E2FROMIO. The distance from the imaging optical system lens 1 to the subject #(
The subject ff1i #) is calculated. Specifically, the system controller 6 activates the spot position detection section 6a to determine the spot light position in the electronic still image determined from the image pickup device 2. Thereafter, the system controller 6 activates the distance calculating section 6b, and uses the information on the spot light reception detection position obtained by the spot position detection section 6a and the object distance obtained in advance for a known subject. A subject distance corresponding to the spot light reception detection position is calculated according to the subject distance stored in FROMIO and the information on the spot light reception detection position.

8 After measuring the subject distance (2) in this way, the system controller 6 starts the lens driving section 3 and adjusts the photographing magnification of the imaging optical system lens 1 to the subject distance before measurement. The position of the black spot of the imaging optical system lens 1 is adjusted with respect to the subject according to the total object distance as described above in -1-.Then, the imaging element 2 is driven, and the imaging optical system lens 1 is adjusted. It goes without saying that the exposure level is adjusted according to the brightness of the subject during electronic image capture of the subject. .

Here, the 1lFI distance principle of the subject distance in the 411] distance device configured as described above will be explained with reference to FIG.

Figure 2 shows the imaging optical system lens 1. It shows the optical positional relationship between the light receiving element J″-2 and the projection unit 4.

In addition, here, the imaging optical system lens 1 is shown as one lens with equal polarization, and the lens center (main;, 'in) 0 is 1.
Although it is shown by a dot, when the imaging optical system lens L is composed of multiple reciprocating lenses, and there is one front principal point and one rear principal point, or L at i f, the imaging optical system lens 1 is 1]
1j side (subject side) is the system from its front principal point (principal point ＼O), and the imaging light and twin system is the rear side of the image sensor 1 (imaging element '' side).
It is enough to add 1 as a system from its backward principal point (principal point ○).

For such an optical system of the imaging optical system lens 1, the guide section 4 is spaced a predetermined baseline length d from the upper point ○ of the imaging optical system [/system 1 (from the device I toward the subject). The direction of the projected light I1 is -1" relative to the optical axis direction of the imaging optical system 1 from the irL to the film surface. In this case, it is tilted inward by an angle θ from the front axis direction, and the spot light is projected in the direction intersecting the optical axis of the imaging optical system lens 1. The optical system of the section 4 is determined. Note that the step shaving section 4 does not necessarily have to be installed at two consecutive positions I, but on the projection axis of the spora light passing through the two positions 1. It is good if it is installed in the position.

The imaging surface of the imaging element 2 is located at a distance b from the principal point O of the imaging optical system I nozzle 1 (a value that is equal to or greater than the focal length of the imaging optical system I nozzle 1 and approximately close to f; b z f an
db≧r) from the rear position! It is determined that With this conversion, the old dllll of the subject distance is carried out under the optical condition that the distance between the imaging plane of the photograph 1 and the principal point O of the imaging optical system lens 1 is b. .

Therefore, suppose that a spot light is projected onto a subject at a distance [from the principal point ○ of the imaging optical system lens 1, and the reflected light is received by the C imaging element 2 via the imaging optical system lens 1. , the spot light (light reception detection position on the elephant imaging 1 11 is a position corresponding to the spot light projection position R of the subject, as shown by P in the figure. In other words, P is the position between the straight line RO and the imaging position) On the other hand, if the subject distance is infinite, the light receiving position of the spot light projected onto the subject by the image sensor 2 is the point of intersection with the main plane parallel to the projection direction of the spot light. Point P~ on the line passing through point O.

Here, in Fig. 2, the subject plane is defined as SR, and the point on this subject (V plane SR) that intersects with the lens optical axis is T. Also, the point that intersects with the lens optical axis on the imaging plane T is C. , object u11 distance ρ does not include length 0T-C, image plane v1j distance 1] C length OC, 2! line length (1 is length 0
1 respectively.

However, from the subject distance to infinity, the above image [imaging surface when displaced from j distance to g] is 1 g of light! When the change in the light reception detection position reaches X, the change mx is the length P
P, , is given as t2'U E'd, and the distances of the antagonistic image positions P and P- on the light receiving surface 2 of the spot light image from the superior position on the light receiving surface are respectively l), 1. ),
, , then the bipedal change amount X can be calculated as x=PP--p-p,-.

Now, if you add 1 to the original raccoon of 3 fft 81 + I m 4,
Beyond that, △OPP~do△OR3 in the 'tsu' system↓1
There is a similar relationship between j and △ocp= and △○TS. From this, the following can be derived geometrically.

△OP P-'s △○ R8 2 → d / x = OS /○P-... (1) △
OCP-Sen△OTS → , Q /b=O810P~... (2
) Since the right sides of equations (1) and (2) are equal, rearranging this results in 47/b = d/x, and rearranging this with respect to the subject distance ρ, we get (1-b-d ・(1 /x) - (3), it becomes possible to calculate the subject distance #tρ from the baseline length d and image plane distance b, which are known in advance, and the amount of change X measured on the imaging plane.

Therefore, the imaging position P~ of the spot light on the imaging plane when the subject distance is infinite is checked in advance and stored in the E2FROMIO.

If we calculate the amount of change X in the imaging position from the imaging position P of the spot light obtained during distance measurement and the information on the imaging position P- stored in the E2PROM 10, we can use this to determine the subject distance g. It becomes possible to measure.

3. Figures 3 and 4 show the flow of the processing procedure and its operation timing in the embodiment device that measures the distance to a subject according to the 11111 distance principle described above. This gauging operation is basically performed by first resetting the focus lens system of the imaging optical system lens 1 to a predetermined reference position (step a), and then resetting the zoom lens system to a predetermined imaging magnification. (Step b).

After performing such preparatory processing, first, the image sensor 2 is caused to expose the subject image without projecting the spotlight from the projection unit 4 (step c), and at the next timing, the exposed subject image is exposed. Read from the image sensor 2 (step d). The subject image read from the image sensor 2 is temporarily stored in the internal memory of the system controller 6.

Thereafter, the projection unit 4 is activated to project the spotlight onto the subject (step e), the subject light image onto which the spot light is projected is exposed (step f), and the projection of the spot light is terminated ( Step g). Then, read out the subject image at the time of light projection from the image sensor 2 (step 11), and return the zoom lens system reset in step b to the original imaging magnification (step 11). i).

As shown in the timing diagram of FIG. 4, the exposure of the subject image by these image sensors 2 and its readout are performed at one field period in synchronization with the vertical synchronization signal V5yne of the still image signal processing system, for example. be done.

Thereafter, the spot position calculation unit 6a is activated to perform calculation for determining the spot light receiving position on the imaging surface (step j). This calculation is performed by subtracting the object image when the spotlight is not projected from the object image when the spotlight is projected, which is determined as described above, and calculating the difference component. This calculation cancels out the image signal components specific to the subject including the background, detects only the signal components of the subject area on which the spotlight is projected, that is, the reflected components of the spot light, and detects the captured image of the subject (screen ) to detect the spot light position on the top.

Thereafter, the data required for the above-mentioned distance measurement calculation, which has been obtained in advance, is read out from the E2PROMIO, and the object distance is calculated using the equation (3) described above (Step D). Then, information on the subject distance determined by this calculation is given to the lens driving section 3, and the focusing lens system, which has been reset as described above, is adjusted to focus on the subject (step 11).
. That is, the focusing lens system is moved to the lens position indicated by the distance to the subject, and the subject is brought into focus.

After the imaging optical system lens 1 is focused on the subject according to the l1ll+distance data as described above, the image sensor 2 is driven to perform main exposure for photographing the subject, and the electronic still image obtained thereby is Record on a floppy disk, etc.

In this processing procedure, as described above, the vertical synchronization signal Vsy is used to perform the imaging of the subject when the spotlight is not projected and the imaging of the subject when the spotlight is projected.
The processing procedure and operation timing are shown in Figs. 5 and 6, and the subject image obtained by the first exposure is It is also possible to perform the object exposure operation by spot light projection simultaneously and in parallel at the time of readout, thereby shortening the processing time of the distance measurement operation.

That is, after exposing the subject with the spotlight in a non-projection state of 1 (step c), the projection unit 4 is activated to start projecting the spotlight (step n). After that, when the exposed subject image is read out from the image sensor 2 as described above,
At step o), at 16J, the image sensor 2 is used to expose the subject onto which the spot light is projected (stellar pull). Thereafter, the projection of the spot light is stopped (step q), and the image of the subject exposed while the spot light is being projected is read out (step ll).
.

By changing the driving conditions for the image sensor 2 in this way, as shown in FIG. This makes it possible to shorten processing time.

7. On the other hand, in the case of the examples shown in FIGS. 3 and 4 shown above, the field parity of both the read out first image and second image is the same, which adversely affects the correlation between the two images. We are emphasizing the advantage that there is no such thing. Note that the above parity is generally defined as 9-2. Assuming that the coin interlace signal is used, this shows whether the one-picture signal is an odd field or an even field.

By the way, when the brightness of the subject is low, that is, when the subject is dark, the exposure for one field period as described above is insufficient, and the spot light image is detected as an image signal at a level sufficient for signal processing. There are some things I can't do.

Therefore, for such a subject, the subject distance in dark conditions is 1
In order to deal with the llll distance, the spot light image detection process may be performed according to the processing procedures shown in the seventh and eighth cases, for example.

That is, when the image of the subject when the spot light is cast g=I Lt in a good condition and the image of the subject when the spot is completely cast η·1 are obtained, the difference component between the images is immediately obtained (step j). Then, in step r), it is determined whether the level of the spot light image indicated by the difference component exceeds a predetermined detection level necessary for signal processing; causes the subject image to be exposed and read out again.

Since this (1f exposure 11, 1f is the previous exposure) was carried out over a field period, for example, the exposure period between 0 and 1f is expanded to 3 field periods and the exposure amount is increased. Under the same exposure conditions, calculate the difference component between the subject image without spotlight projection and the subject image with spotlight projection, and determine whether the level of the spot light image is the predetermined detection level required for signal processing. Discriminate whether it exceeds or not.

If the detection level of the spot light does not reach the predetermined threshold even after increasing the exposure amount in this way, for example, increase the exposure time of the subject to 6 fields and detect the spot light image in the same way. Do this.

If a spot light image of a sufficient level cannot be detected even after doing this, for example, the release button is pressed 90 degrees to notify that distance measurement is not possible or AF control cannot be performed.

In this case, the time required to detect a spot light image, that is, the time from the start of the first exposure (step c1.) to the end of the spot position calculation (step J), is the time required to detect a spot light image with one field of exposure. If possible, 5 fields (
14 fields (approximately 230 m5ec), and in the center a spot light image can be detected by exposing the next 6 fields. In other words, even under the longest conditions, there are 29 fields (approximately 480 m5ec).

Incidentally, the timing diagram shown in FIG. 8 shows an example in which a spot light image is detected by exposure of three fields of "2 and 1".

In this way, by adjusting the exposure amount to the subject and detecting the spot light image accurately and sharply, even when the subject brightness is low, the subject distance can be accurately determined to the open side. However, it becomes possible to effectively adjust the focus of the focusing lens system to the subject.

By the way, in the above-mentioned length embodiment, the E2FROM 10 stores information on the image forming position P~ of the spot light image when the subject distance is infinite, and this information is used to calculate the subject distance.

However, in practice, information on the imaging position of the spot light image at two subject positions whose subject distances are known in advance is
It is preferable to store it in 2FROMIO and use it to calculate the subject distance. At this time, information on the imaging position of the spot light image at the above two subject positions should be stored in accordance with the various optical properties of the imaging optical system lens l, for example, depending on the lens type, imaging magnification, etc. For example, it becomes possible to perform object distance measurement calculations that effectively deal with various imaging conditions.

That is, in FIG. 9, a plurality of object distances ρ1. ．． Q2.1
Image formation positions PL, P2. As shown in the relationship of PX1, the amount of displacement xi,
2. x is x −px −p～ (4)xi
-pi -p~...(5)x2=p
2-p~...(6) are given respectively. Here, from the relationship xLXρl = x2 Spot light imaging position p- at infinity
If we rearrange, p~=(,Q2p2-J)Ipl)/(,Q2-,Ql
)...(7) This is expressed as (3) regarding the subject distance Dx.
Substituting into the equation and solving it reveals the following relationship: (8) 2.

Here, if we focus on the distance ρ1 where the subject distance is known and solve Equation (8) above, we can easily calculate the subject distance 11x by simply measuring the imaging position pX of the spot light from the unknown subject. becomes possible.

However, the reference subject distance is 01. ．． If 172 is defined as, for example, 1 m and 2 m, it can be seen that the following actually holds true, and a relationship that organizes this holds true.

Therefore, by substituting this equation (9>) into the above equation (8) and eliminating the constant term b-d, the spot measured on the imaging surface can be calculated as follows: It becomes possible to calculate the subject distance pX simply by performing calculations according to the imaging position pi, p2.I)X of the optical image.

It can be seen that the deopter value Dx, which is object distance information in reciprocal expression that is easy to correspond to the control of the focusing lens system, can be calculated as follows. In other words, the subject distance is ρ1. i) Imaging position pi of the spot light when 2,
It goes without saying that if p2 is determined in advance, it may be directly calculated as the subject distance 3.

What should be noted here is that each of the above-mentioned calculation formulas for calculating the subject distance Nx (or deopter value) has its numerator and denominator as shown in equations (11) and (12), respectively. The dimensions are the same.This means that by multiplying the information on the spot light image formation position pl, p2.px by an arbitrary constant k, the object MρX (or diopter value 1 )X) means that it cannot be turned into a pot. That is, each of the above-mentioned imaging (:1 device pl, I)2
．． I) Not only may the reference position on the imaging plane of 15 for determining X be an arbitrary position, but also the intermediate system of 15 that measures this may be entirely arbitrary. It means that.

As a result, if the calculation algorithm is set to calculate the subject distance tltIUx in a series of steps, the imaging position of the sub-no I light image on the imaging surface of the image sensor 2 can be determined by MSK. In the unit system: Without calculating l11+11, for example, the number of pixel pitches or the detection timing (time) of a spot light signal on the scanning line of an electronic still image signal:
1-i
Becomes J Noh. In addition, using the 5 ffit 1111 data directly in this way
7'5, which increases the iJ performance, has the effect of reducing the number of errors introduced into the arithmetic processing and improving the accuracy of the calculation.

Note that the imaging position that has moved upward 1) 1. (For example, 7) After the Miko still camera is introduced and set up, the first
0 Figure not shown: Follow the processing procedure to determine the reference object distance DI.
, Subop I at ρ2, optical viscosity position i + vinyl pl, p2 is 5
All you have to do is measure 7 and transfer it to E'FROMIO.

To explain the processing procedure of the data set to the E2FROM l[l shown in FIG. A), initially set the control parameter k to [ko] (
Step L). In this state, the above imaging light/twin system lens i
The zooming 1 non-zero system is set to the above control parameters.
The chart is set at the predetermined first imaging magnification position (step c), and in this state, the chart is placed at the predetermined first subject reference position fi (step D). This char h (
The first subject reference position for setting the reference subject is:
For example, from the principal point O of the imaging optical system lens 1 to the subject Mti#
It is determined as the position where ρ1 or 1 m. In this way, the imaging position Plk of the spot light image at that time is determined according to the processing procedure described above for the chart set at the spot light image position (1m0') (steps E and F).

After that, apply the chart 1 to a second photographic reference device,
For example, set the lens at a position 2 m from the main lens, I, \0 (step G), and similarly determine the imaging position P2k of the spot light image at that time (steps G, H). The image formation position Plk, P2k of the spot light image at each of the above-mentioned positions obtained in this way is managed according to the photographing rate ε of the zooming lens system described above (=I), and the control parameter k is incremented and the information on the imaging position of the spot light image at the next imaging magnification is obtained in the same way (
Steps J, K).

Then, the plural imaging magnifications determined by Cp, the above-mentioned 7 at It is registered in the E2FROM]O as information for visually measuring the object distance regarding the imaging optical system lens 1 (step L).The symbol Vk in flowchart 1 means "for any (all) k". .

In the above manner, the subject distance ρX is added to E2FROMIO.
Information necessary for the calculation process (imaging position of the spot light P l
k, P 2k is the optical characteristic of the imaging optical system lens 1,
For example, if you register one digit to correspond to various shooting magnifications,
Subject distance: chick's 4I111I (!By selectively using these stored data according to the conditions and executing the calculation process described above, the subject distance Dx can be easily determined, 1], and with good viscosity. 7'J Noh.

By the way, the detection of the GAR position PX of the spot light image placed on the imaging surface 1 of the above-mentioned image sensor -r-2 is performed as follows.

In Fig. 11, the above-mentioned spot light projection I, 1 part 4 is provided in the horizontal scanning direction of the image sensor 2, and the image formation position of the spot light image reflected by the subject is changed depending on the change in the subject distance. FIG. 12 is a diagram showing an example of a failure of the spot light imaging position detection circuit when the optical system is set so as to be displaced in the scanning direction.

This detection circuit controls the operation of the clock generator I2 under the control of the processor 11, generates the gating signal Sν and the sample signal Sb, and drives the A/D converter 13, as shown in FIG. do.

In connection with the readout scan of the captured image signal from the image sensor 2, 1. By A/D converting the captured image signal while sampling it over a scanning line period and storing it in the memory 14, one line of image signals including the spot light image shown in the shaded area in FIG. 12 is extracted. do. Then, the processor 11 compares and determines the level of the image signal for one line stored in the memory 14 for each sampling point, and detects the information of the sampling point n that takes the peak level as the imaging position of the spotlight. It is composed as follows.

Alternatively, the above-mentioned three spot light projection units 4 may be provided in the vertical scanning direction of the image sensor 2, and the imaging position of the spot light image reflected by the subject may be changed in the vertical scanning direction as the subject distance changes. When the optical system is determined so as to be displaced as follows, the spot light imaging position detection circuit is constructed as shown in FIG.

In this case, the clock generator 22 is driven under the control of the processor 21, and the gate circuit 23 is controlled to open and close using the gate pulse cp to generate image signals at the center of the screen on each horizontal scanning line, as shown in FIG. Extract bamboo. Then, the image signal at the center of the screen gated in this way is integrated using the integrator 24, and this is integrated by the A/D converter 2.
After A/D conversion via 5, the data is stored in memory 26 in association with the horizontal scanning line. Such signal extraction processing is executed for the entire screen of the image sensor 2, and the memory 26
The vertical signal sequence of the signal component at the center of the screen is obtained.

In this way, the level of the image signal at the center of the screen stored in the memory 26 is compared and determined for each line by the processor (1).Then, information on the horizontal scanning line n where the peak level is taken is obtained. Since the signal level of the horizontal scanning line on which the spot light image is formed becomes high, this is detected as the image formation position of the spot light.

In this way 1. According to the spot light viscous image position detection circuit formed by -1, the horizontal scanning direction or vertical Signal sequence ID in the scanning direction (
n)l is as shown in Figure 15, and the signal level in the part where the spot light image is formed is higher than in other parts. Therefore, by simply finding the signal position (sampling point or horizontal scanning line) at which the peak level in this signal sequence (D(n)l occurs), it is possible to find the imaging position of the spot light with high precision.

Incidentally, the detection of the spot light image is performed by detecting the subject image when the spot light is projected and the spot light at stage f1. J
This is done after finding the difference between the image of the subject when L is not present and removing background noise components. Therefore, in practice, the signal sequence in the horizontal scanning direction (vertical scanning direction) from the subject image when spot light is projected onto the detection circuit configured as described above is Ml = (DI(n)
), and the signal sequence M2 in the horizontal scanning direction (vertical scanning direction) from the subject image when no spot light is projected
D2(n)l, respectively, and the imaging position of the spot light image can be determined according to the processing procedure shown in FIG.

That is, first, the difference component M3 = ID between the signal sequence Ml = fDl(n)l and the signal sequence M2 = ID2(n))
3(n)1 is determined (step P). Then, the signal sequence M3 = (D3(n)l, the point n p [D 3(n p) = maxD 3(
n)] (step Q). Then, it is determined whether or not this maximum signal level value D3 (n1)) exceeds a predetermined threshold Th (step R). If the determination condition based on this threshold Th is not satisfied, as described above, error processing is performed to Exposure to the image Il! 1 interval is reset to a longer time, and the signal sequence extraction process is repeated again.

If the maximum signal level value 2D3(np) exceeding the threshold Th is detected, the interpolation algorithm method as shown in FIG. Then, the imaging position P of the spot light is determined (step S).

That is, the point np at which the No. 15 level detected as described above is the maximum is determined at each predetermined sampling interval or at each predetermined pixel pitch in the image sensor 2, and therefore is not necessarily a spot point. light knot Ig
! It does not necessarily indicate the exact location.

Then, when the point np where the signal level is maximum is found, it is estimated that it exists at the actual maximum signal level or within the error range of 172 of the above → non-pulling interval or pixel pitch, and the adjacent sampling point (adjacent pixel)np-]
, , and the signal levels at jnl +1 are determined, respectively. And these adjacent sampling points (adjacent pixels) np-1
, np +1 and the signal level at the point np where the signal level is maximum are determined as a and b, respectively, and by apraxically performing the interpolation calculation 3, we obtain the difference shown in Figure 1-7. The actual imaging position p of the spot light may be determined with precision.

By the way, in the spot light image detection process, the image sensor r2
When the output of 1! is saturated, it is detected as described above. The signal sequence M=fD(n)l may have a plurality of maximum transmission level points I','f as shown in FIGS. 18(a) and (b).

In addition, since the spot light image is detected through the imaging optical system lens 1, which is being adjusted to the subject, the spot light image from the subject is out of focus. It is common to capture optical images. Even when a spot light image is viewed one by one in such an out-of-focus state, the spot light image produces a so-called blur, and as described above, the detected signal sequence M= f
D(n)) has a plurality of maximum signal level points as shown in FIGS. 18(a) and 18(b).

4 Therefore, when such a signal sequence M is detected, for example, the maximum position npilaxl and the minimum position npfmJnl of the region where the signal level goes around twice a predetermined threshold value are determined, and, for example, a - D 3 ( n pfm jnl) -D
3(n plminl -1->b -D3(
n pimaxl) -D3(n p1maxl+
1), the center of the spot light image showing the flat signal level region is set as spot completion 1 image 1 vertical position p
All you have to do is ask for it.

The basic configuration of the distance measuring device according to the present invention and its functions and effects have been described above, but in practice, the conditions of the optical system etc. may be set as follows. This practical design concept will be explained with reference to FIG. 19.

iul f? 12 The farthest distance of the target object is gr,
Distance lately! IN, the effective screen width in the random line length direction of the imaging cable 2 is W, and as described above, the projection direction of the spot light is 9;j in the optical axis direction of the imaging optical system lens 1, and the angle θ is
Assuming that the object is tilted, the farthest distance described above is from f7p to the nearest distance ρ, and the inverse 11 light image of the spot light from the subject in the distance range of &111 is calculated by parallax on the imaging surface of image sensor 2 To detect it as the minimum, as shown in Fig.
The imaging position of the spot light image RN reflected by the odor-C object may be set to a symmetrical position with respect to the center C of the image sensor 2. Therefore, the JQ of the above spot light
Regarding the angle θ of the goods, it is sufficient to satisfy the following condition.

In addition, when the subject is at the closest distance (iN), in order to make the spot light image circled by the subject visible on the imaging surface of the image sensor 2, it is necessary to pay attention to the vertical position of the UN. Similarly, when the object is at the farthest distance MF, in order to form a spot light image reflected by the object on the imaging surface of the image sensor 2. , it is necessary to satisfy the relationship formed by paying attention to the Up position.

Optical conditions may be determined so as to satisfy each of these conditions.

More specifically, the effective screen size of the image sensor 2 is - Taking typical values for a 1/2-inch solid-state imaging device inside the membrane, the effective screen size is [6.4 mm] in the horizontal direction and [6.4 mm] in the vertical direction. It is given as [4,8mm]. Therefore, the direction of the base line length in which the projection section 4 is provided is determined as the upper part of the imaging optical system lens 1 in the vertical direction, and the base line length d is [35+nm]
shall be set to .

7 Also, as the imaging optical system lens l, the focal length f or [10
It is assumed that a zoom lens of ~30+nml and a focusing range (NN-Llp) of [0.8~5.0ml] is used.

When using such an optical element, for example, the reference focus distance il+1 (the position of the focusing lens system that is reset to the distance measurement IIji) is set to, for example, the logarithmic harmonic ψ of the focusing range (ρN-ρF). =1400+n is selected as a point. Furthermore, since the projection angle θ of the spot light described above may be set so that the relationship formed by the above equation (14) holds, θ−j
an-0,0254=1.4530°=1'27'
It turns out that it is sufficient to set it to 12'.

In addition, in practice, it is not only necessary to ensure that the spot light image is detected on the light receiving surface of the image sensor 2, but also to consider the range of the AF parallax for ease of use of the camera. Screen size W[-4,8ml1
1], if we take 1/4 of that as the screen effective width W, it is sufficient to set it as w - (1/4) W = 1.2 mm, and taking into account the assembly setting error of the angle θ mentioned above, Assuming tan θ - 0,025 ± 0.005, the design conditions shown in Equations (15) and (1G) above are the limit condition when θ is the minimum (tan θ = 0 at nearest distance 111tDN). .02)
Then → b ≦ 0. GX 800 ÷ (35-
It is sufficient to satisfy 800X O,02)≦25.29, and the limit condition (
At the farthest distance Mρ, tanθ = 0.03), 9 → b ≦ 0.6X 5000÷ (5000X
O, 03-35)≦28.09. Therefore, it follows that the imaging distance b (lens focal length sr that defines the imaging magnification) may be set to, for example, [25 mm] or less.

Here, in the zooming distance range [10 to 30 mm] of the imaging optical system lens l mentioned above, the subject distance i1+1
If you reset the zoom system to only one limited shooting magnification at one focal point, and then return to the original shooting magnification after completing the a+++ range, the variable range of the shooting magnification becomes very large. I can't deny that it will happen. Additionally, it cannot be denied that the processing time required to drive the zooming lens system becomes longer.

Therefore, as mentioned above, the zooming jump range is [10 to 3
0+nm], if the range is as wide as
%, a plurality of standard photographic magnification points may be determined, and one of the 1.1 J points may be selected depending on the condition of the lens system to measure the object distance. For example, in the above example, the zooming distance range [10 to 301] of 0 is 10 -
14.3 nun ■ 14.3 ~ 20.5 mm ■ 20.5 ~ 29.45 (30) Divide into three ranges nv based on 'Hi ratio, and set the standard shooting f8 rate point for each distance range (] ) 112.0 mm L7.2 ll1 m ■ 24.6 mm The total distance to the subject may be determined as i1+11.

In this case, if the geometrical relationship is maintained accurately, the area above the above-described imaging magnification f = [29, 45] will protrude from the target area for accurate distance measurement. However, considering [29,45ri30.00],
If this is included in the scope of control mentioned in ■ above,
In practice, it becomes possible to measure the object distance without causing problems and use it for AF control.

In addition, when setting a plurality of reference shooting rate points in this way and selectively using them to measure the subject distance, for example, the reference shooting point at the shortest position from the current shooting speed point can be set. Although a magnification point may be selected, the direction of the reset may be determined in advance, and the zooming lens system may be reset to the reference shooting magnification point on the tele side or wide side. Further, the positions of the plurality of sub-photographing magnification points may be determined according to the specifications while satisfying the above-mentioned conditions, and are not particularly limited.

Furthermore, if the number of settings for this prefectural semi-photographing magnification point is sufficiently large and the design is such that the magnification error with respect to the shooting point to be taken can be practically ignored, then the magnification return operation of the zoom lens system described above will be (corresponding to step j in the flowchart) can be omitted, making it possible to further speed up the process.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto. For example, when obtaining a spot light image, two consecutive fields or two consecutive fields are used.
Although two image signals of the same parity field 2 were used, the two images do not necessarily have to be consecutive. It is also obvious that the concept of the parity field can be extended to any interlacing method. Further, there is no need to limit the number of images to be processed to two. At this time, it is only necessary to control the exposure so that the exposure values of the plurality of field images are equalized, thereby effectively removing the extra 1≦ component of the subject and obtaining a spot light image with high precision. becomes possible. Furthermore, the algorithm for detecting a light image (spora), and for ejecting the optical image can be modified in various ways, and in short, the present invention can be implemented in various ways without departing from the gist of the invention. be able to.

[Effects of the Invention] As described above, according to the present invention, it is possible to effectively and highly accurately measure a distance to a subject by effectively utilizing an image sensor for capturing and inputting an image of a subject. Furthermore, even if the optical characteristics of the lens of the imaging optical system for forming the object image on the image sensor vary, the distance from the object can be accurately detected accordingly. As a result, the configuration of the ff1ll distance system in an electronic still camera can be greatly simplified, and it is only necessary to provide a spot light projection section at a position separated by a predetermined base line length from the imaging optical system lens. There are great practical effects, such as being able to effectively avoid camera design problems.

[Brief explanation of drawings]

The figures show a distance measuring device according to an embodiment of the present invention, and FIG. 1 is a schematic diagram of the main parts of the device according to the embodiment, and FIG. The figure shown in Figure 3 is 4.
Figure 4 shows an example of the 1st code of the set processing procedure.
5 is a diagram showing the operation timing of the ill+distance processing procedure shown in FIG.
This figure shows the operation timing of the distance measurement procedure shown in FIG. 5, FIG. 7 shows the third example of the distance measurement procedure, and FIG. 8 shows the operation of the distance measurement procedure shown in FIG. FIG. 3 is a diagram showing timing. Furthermore, FIG. 9 is a diagram showing an optical system for explaining the principle of 4 71111 distance of subject distance in the embodiment device.
Figure 0 is 7Ill] Figures 11 and 12 show the formation of a spot light image when the direction of the line length is set in the underwater direction. Figures 13 and 14 are diagrams showing a first example of image position detection, and Figures 13 and 14 are diagrams showing a first example of spot light image formation position detection when the direction of the star line length is set in the vertical direction, FIG. 15 is a diagram showing an example of a signal of a detected photographic subject image, FIG. 16 is a diagram showing the advantage of the spot light image frame+S position detection process FIl by peak level detection, and FIG. 17 is a diagram showing the result of 16! It is a figure which shows the concept of a sleeve processing push in I standing detection. FIG. 18 is a diagram showing an example of a general spot light image detection signal, and FIG. 19 is a diagram showing an optical system for explaining the design conditions of the embodiment apparatus. 1... Photographing (elephant optical system lens), 2... Imaging element (imager), 3... Lens drive unit, 4... Projection unit, 5...
Projection unit driver, 6... system controller, 6
a. Spot position clearing unit, 6b... Distance calculation unit, 7.
・Operation unit, 8... Position sensor, 9... Illuminance detection unit, 5 10... E2 FROM (memory).

Claims (1)

[Scope of Claims] (1) An imaging optical system lens for forming a subject image on the imaging surface of an image sensor, and a lens provided at a position separated from the imaging optical system lens by a predetermined baseline length, a projection unit for projecting a spot light toward a subject to be imaged through an optical system lens; A means for positioning at a focal position, and an imaging optical system lens positioned at the predetermined focal position, the image sensing device detects a reflected light image of the spot light projected from the projection unit by the subject; means for determining the imaging position of the spot light image on the imaging surface of the imaging element; means for calculating the distance from the imaging optical system lens to the subject according to information on the imaging position of the spot light image; and this means A distance measuring device comprising means for adjusting the focus of the imaging optical system lens on the subject according to the distance information calculated by. (2) The means for calculating the distance to the subject includes information on at least two photographing distances known in advance and information on the imaging position on the imaging surface of the spot light reflected by the subject at each of these photographing distances. Information on the imaging position of the spot light reflected by a subject whose photographing distance is unknown on the imaging surface, information on the photographing distances stored in advance in the storage means, and each photographing distance. The distance measuring device according to claim 1, wherein the distance measuring device calculates the photographing distance of the object according to information on the imaging position of the spot light in terms of distance. (3) An imaging optical system lens for forming a subject image on the imaging surface of the imaging device, and a position separated from the imaging optical system lens by a predetermined base line length, and a projection unit for projecting a spot light toward a subject to be imaged, and means for setting the imaging optical system lens to a predetermined imaging magnification prior to the imaging operation of the subject by the imaging element. The reflected light image of the spot light projected from the projection unit by the subject is detected by the image sensor through the imaging optical system lens set to a predetermined imaging magnification, and the image is detected on the imaging surface of the image sensor. means for determining the imaging position of the spot light image on the imaging surface of the spot light reflected by the object; What is claimed is: 1. A distance measuring device comprising: means for calculating the distance to the subject; and means for adjusting the focus of the imaging optical system lens on the subject according to the distance information calculated by the means. (4) The focusing adjustment of the imaging optical system lens on the subject according to the calculated distance information is performed by adjusting the imaging magnification of the imaging optical system lens, which was set to a predetermined imaging magnification at the time of detecting the imaging position of the spot light image, to the original shooting magnification. The distance measuring device according to claim 3, characterized in that the distance measuring device is measured after returning to the magnification. (5) The means for calculating the distance to the subject includes a means for storing data regarding predetermined items of the imaging optical system lens corresponding to the imaging optical system lens, and when determining the imaging position information of the spot light image. The distance measuring device according to claim 2, wherein data corresponding to the imaging conditions of the imaging optical system lens is read from the holding means, and the shooting distance to the subject is calculated using this held data. Device. (6) The means for determining the imaging position of the reflected light image by the subject of the spot light is configured to determine the image formation position of the image of the reflected light from the subject when the spot light is irradiated, and the light image determined from the image sensor when the spot light is not irradiated. and, when the level of the difference component of these light images exceeds a predetermined threshold, the imaging position of the spot light indicated by the difference component on the imaging surface is determined, (1) When the level of the difference component of the light image is less than a predetermined threshold value, the imaging time of the light image by the spot light irradiation is reset to a longer time, and the difference component of the light image is determined. The distance measuring device described in .