JP2002148511A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera capable of performing range-finding to a low- contrast subject and in a dark scene without requiring an additional light source. SOLUTION: In this camera, a subject image is detected through a range- finding optical system and a pair of image signals is outputted by at least a pair of sensor arrays 10a and 10b. Strobe light is irradiated by making a discharge light emitting tube emit light at a strobe light emitting part 5 having a xenon discharge tube. A strobe window 5a condensing and projecting one part of the strobe light is arranged in a direction orthogonal to the longitudinal direction of the sensor arrays 10a and 10b, and a photographic lens 2 is focused by a focusing part 19 based on output from at least a pair of sensor arrays 10a and 10b in the case of irradiating the strobe light to the subject 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto-focus camera, and more particularly, to an auxiliary light for an auto-focus camera of the type that focuses on a photographic lens using an image signal of a subject. It is about improvement.

[0002]

2. Description of the Related Art An image signal of a subject is obtained when the place where the subject exists is dark or when the subject has no contrast.
It becomes ambiguous and is not sufficient for the focusing operation.

[0003] Therefore, cameras have long been projecting light,
As a light source for AF (autofocus), for which a so-called auxiliary light technique for assisting focusing has been known, in particular, a light from a strobe can be used.
This is known from Japanese Patent Publication No. 146331. This eliminates the need to have an additional light source for AF.

[0004]

However, the technology disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 62-146331 has a problem in that it has a configuration requiring a movable part and is poor in reliability.

Further, it is generally necessary to uniformly irradiate the light of a strobe in a screen, and there is a problem that even if the light is irradiated on a so-called low-contrast subject, a contrast for distance measurement cannot be formed. .

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and has as its object to provide a camera which does not require an additional light source and can measure a low-contrast subject even in a dark scene. I do.

[0007]

That is, the present invention provides a distance measuring optical system, a sensor array for detecting an image of a subject through the distance measuring optical system and outputting a pair of image signals, and a discharge arc tube. A strobe means for emitting strobe light by causing the discharge arc tube to emit light; and a projection means for condensing and projecting a part of the strobe light in a direction orthogonal to a longitudinal direction of the sensor array. Light means; and focusing means for focusing a taking lens based on an output of the sensor array when the object is irradiated with the strobe light.

According to another aspect of the present invention, there is provided a distance measuring optical system, a sensor array for detecting an image of a subject via the distance measuring optical system and outputting a pair of image signals, and a discharge arc tube. A camera comprising: a strobe means for emitting strobe light by emitting light from a tube; and a focusing means for focusing a taking lens based on an output of the sensor array when the subject is irradiated with the strobe light. Wherein the strobe means irradiates the object with strobe light having a pattern-like infrared component and a visible light component of uniform irradiation.

In the camera according to the present invention, an image of the subject is detected via the distance measuring optical system, and a pair of image signals are output by the sensor array. In addition, strobe light is emitted when the discharge arc tube emits light by strobe means having the discharge arc tube. In a direction orthogonal to the longitudinal direction of the sensor array, a light projecting unit that condenses and projects a part of the strobe light is disposed, and the light projecting unit irradiates the subject with the strobe light. Focusing of the photographing lens is performed by focusing means based on the output of the sensor array.

In the camera according to the present invention, an image of the subject is detected via the distance measuring optical system, and a pair of image signals are output by the sensor array. In addition, strobe light is emitted when the discharge arc tube emits light by strobe means having the discharge arc tube. Further, based on the output of the sensor array when the object is irradiated with the strobe light, focusing is performed by the focusing means to focus the photographing lens. When the strobe light is irradiated onto the subject, the infrared component of the strobe light is formed into a pattern, and the visible light component of the strobe light is uniformly irradiated.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2A is a perspective view showing the external appearance of a compact camera, showing a configuration of a camera according to a first embodiment of the present invention.

A photographing lens 2 is provided on the front of the camera body 1.
In addition, a finder objective window 3, a lens 4 for distance measurement, and a strobe window 5a having a function of condensing and projecting a part of light are provided. On the upper surface of the camera body 1, there is arranged a release switch 6 and a display section 7 composed of a display LCD.

FIG. 2B is a diagram showing the relationship between the flash unit and the distance measuring lens in FIG.

The strobe includes a xenon discharge tube (Xe tube) 5b, which is a strobe light emitting section, and a strobe window 5a for projecting light. Because the photo screen is usually landscape,
It is preferable that the Xe tube 5b be oriented sideways so that the length direction matches the longitudinal direction of the camera.

The distance measuring device includes a plurality of sensor arrays 1.
Two light receiving lenses 4 having parallax at 0a and 10b
It is assumed that an object image incident from a and 4b is detected, and an object distance L is obtained from the relative position difference.

Here, the sensor array 10a,
Three pairs of 10b are prepared. These sensor arrays are prepared for distance measurement at the center and left and right of the screen, and have subject detection areas 14C, 14L, and 14R.

The strobe emits uniform visible light 11 and contrasting infrared light 12 as auxiliary light.

Next, the principle of distance measurement of this camera will be described with reference to FIG.

FIG. 1 is a block diagram showing an electric system of a main part of a compact camera according to a first embodiment of the present invention.

In FIG. 1, a CPU 17 is an arithmetic control means for performing sequence control of the camera. And
The CPU 17 includes a flash unit 5, a release switch 6, a display unit 7 having the above-described Xe tube 5b, a shutter unit 18, a focusing unit 19, and an EEPROM 20.
And a distance measuring device 21 are connected.

The CPU 17 detects whether or not the user has operated the release switch 6 at the time of photographing or the like, and controls the distance measuring device 21. Then, the photographing lens 2 is operated via the focusing unit 19 based on the obtained information. In order to control exposure, a shutter unit 18 is provided.
And the strobe light emitting unit 5 is controlled. If a sufficient image signal cannot be obtained at the time of distance measurement, the strobe light emitting unit 5 is controlled, and a steady light removal circuit 23 described later in the distance measurement device 21 is controlled to perform distance measurement.

The display unit 7 is provided with a CPU 1 to indicate the mode set at the time of photographing and the number of frames of the photographed film.
7. Variations in camera parts and assembly during distance measurement and focusing are checked at the time of manufacture, and are stored in the EEPROM 20 as correction coefficients.
Thus, the control in which the variation is canceled is performed.

The distance measuring device 21 includes a sensor array 10a
And 10b, light receiving lenses 4a and 4b, A / D converter 2
2 and the stationary light removal circuit 23.

The optical system of the distance measuring device 21 and the sensor array 10
And 10b will be described later.
The outputs a and b are converted into digital signals by the A / D converter 22 and input to the CPU 17.

In the stationary light removing circuit 23, only the distance measuring light projected from the camera side is integrated, and the subject is illuminated by sunlight or artificial illumination.
The background light incident on a and 10b is removed. The function of removing the constant light is used at the time of projecting the auxiliary light, so that the effect of the auxiliary light contrast can be enhanced even in a bright place.

The distance between the principal points of the light receiving lenses 4a and 4b is referred to as a base length B. The sensor arrays 10a and 10b which are placed behind the light receiving lenses 4a and 4b to form an image.
If the distance to is f, the image of the subject 25 at the distance L is
The two sensor arrays are formed with a relative positional difference of x. This x is x = B · between the above B and f and the distance L.
f / L. Therefore, the main technique is to detect the subject images on both sensor arrays.

Here, the reason why three pairs of sensor arrays are provided will be described.

This corresponds to screen 27, as shown in FIG.
No matter where the subject 25 exists, the sensor field of view 1
4 is designed so that focusing can be performed, and is not limited to three points, but three points will be described here as an example to simplify the description.

As described above, by disposing the two light receiving lenses vertically, the base line length direction becomes the vertical direction.
The shift direction of the image to be detected is also up and down, and the arrangement direction of the pixels of the sensor array is also up and down. Thereby, it is preferable that the contrast of the image signal to be detected is formed in the vertical direction.

As described above, in order to form a contrast in the up-down direction and to give the same contrast to a plurality of distance measuring points side by side in the screen, FIG.
Alternatively, as shown in FIG.
It can be seen that an auxiliary light form (infrared light 12) for projecting an image of the tube 5b itself is preferable. Light is projected onto each of the three horizontal distance measuring points, and light that is narrow in the vertical direction is preferable.

In addition, there is a concept that independent light spots are projected on each of these three points. However, it is necessary to prepare a new light source, and the space and cost of a light emitting element serving as a light source and its driver are required. Becomes Also,
It is difficult to obtain light as strong as a strobe light using an LED or a lamp. Therefore, if another dedicated strobe device is provided, an increase in the size of the camera is inevitable.

Therefore, generally, X arranged in the horizontal direction is used.
By making the direction of the e-tube 5b orthogonal to the direction of deviation of the image to be detected, it is possible to efficiently form a contrast at many points in the screen. In the AF of the image detection method, distance measurement cannot be performed on a subject having no contrast, but accurate distance measurement can be performed by using such auxiliary light in combination.

FIG. 4 is a flowchart of the control performed by the CPU 17 when measuring the distance of the camera having such a configuration.

When the distance measurement is started, first, in step S1
, An image is detected by the sensor arrays 10a and 10b. The output photocurrent of each sensor is stored in an integrating capacitor (not shown), and the voltage converted value is A /
The data is A / D converted by the D conversion unit 22 and input to the CPU 17.

However, if the brightness is low or the subject has no contrast, accurate distance measurement cannot be performed, and these determinations are made in steps S2 and S3. That is, it is determined in step S2 whether the contrast is low or not in step S3.

As a result, if neither the low contrast nor the low luminance is reached, the process proceeds to step S6, and if it is either the low contrast or the low luminance, the process proceeds to step S6.
The process proceeds to step 4, where the background light is stored. Next, in step S5, an auxiliary light is irradiated by flash emission control,
Image detection is performed using the reflected signal light.

Since the strobe light is provided with a contrast, it forms an image with contrast on the subject 25, thereby enabling accurate distance measurement.

FIG. 5 is a diagram showing the details of the photocurrent integration section of the sensor output for image detection.

One sensor 30 in the sensor array will be described. That is, the integration circuit 32 is connected to the sensor 30 via the switch 31. The integration capacitor 32 and the A / D converter 22 are connected to the integration circuit 32. In addition, a steady light removing circuit 35 is connected to the sensor 30 via a switch 34.

The integrating circuit 32 amplifies the photocurrent output from the sensor 30 and guides the amplified photocurrent to the integrating capacitor 33.
Since the charge of the integration capacitor 33 at the time of integration is sampled and held by turning off the switch 31, the charge may be read by the A / D converter 22 described above.

Also, during the steady light removing operation, the switch 3
When the switch 4 is turned on, the steady-state photocurrent flows to the steady-state light removing circuit 35, and only the photocurrent increased during the emission of the auxiliary light is led to the integrating circuit 32. Therefore, when the reflected signal light does not return from the subject, the integration capacitor 33
No charge is stored in the switch 31 and when the switch 31 is on,
The integration capacitor 33 is charged according to the amount of the reflected signal.

Switch 3 in synchronization with strobe light emission off
4 is turned off, the output of the integrating capacitor 33 becomes
An image signal based on the reflected signal is output as a result of the A / D conversion.

Returning to the flowchart of FIG. 4, the CPU obtains the image obtained in this manner in step S6.
At 17, the subject distance is calculated. And step S
At 7, the focusing unit 19 controls the photographing lens 2 to enable accurate focusing on any subject.

As described above, in a camera capable of measuring a distance of three points, the processing operation up to the above-described step S6 may be performed for three points, and the closest distance may be selected for focusing.

FIGS. 6A and 6B show an example of the configuration of the strobe light emitting section 5 in the first embodiment. FIG. 6A is a sectional view and FIG. 6B is a perspective view.

The reflectance 37 is provided in a direction excluding the front surface of the Xe tube 5b so that the light from the Xe tube 5b is irradiated in front of the strobe. A slit 38 is formed in a part of the reflector 37 behind the Xe tube 5b. The luminous flux passing through the slit 38 is reflected twice inside the prism 39 disposed further rearward, is condensed by the lens 40 that has been cut with visible light, and is projected on the subject.

As described above, since only the infrared light is condensed for the auxiliary light and projected, the condensed pattern is not printed on the photograph while using the strobe. .

The distance measuring sensor has a sensitivity distribution from visible to infrared, and the light of the Xe tube 5b contains an infrared component as much as visible light, so that uniform visible light 11 is used as auxiliary light. 6 and the infrared light 12 having a contrast overlap,
It is projected as shown in (b). However, for the distance measuring sensor 10, the light is incident as shown in FIG. 6C. An image is formed by the contrast between the infrared light 12 and the visible light 11, and correct focusing can be performed on a low-contrast subject.

Further, since the length direction is secured along the length of the Xe tube 5b, it becomes auxiliary light corresponding to a plurality of distance measuring points arranged as shown in FIG.

As described above, according to the first embodiment, while using the visible light component of the strobe light for exposure,
It is possible to provide a camera capable of performing focusing and photographing without an objectionable subject using an intense light of a strobe by using an infrared component particularly for distance measurement.

Next, a second embodiment of the present invention will be described.

FIG. 7 shows a second embodiment of the present invention and is a sectional view of an optical system. In the following embodiments, the same parts as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The second embodiment is an example applied to a single-lens reflex camera, and detects the in-focus state of the photographing lens 2.

The rear of the photographing lens 2 (right side in FIG. 7)
Then, a surface 43 corresponding to the film surface is located. This surface 43 represents a surface which is also called a planned image forming surface or a film equivalent surface. The condenser lens 44 provided near the surface 43 has a function of guiding the image formed by the photographing lens 2 to the re-imaging lens 46 via the mask 45.

The image formed through the re-imaging lens 46 is formed on the sensor arrays 47a and 47b. Here, when the subject image is formed on the film surface (I)
In the front focus state (F) and the rear focus state (B), the position of the image formed on the sensor arrays 47a and 47b changes, as apparent from the optical paths indicated by the solid lines, broken lines, and dashed lines in the figure. It is.

By monitoring the image positions on the sensor arrays 47a and 47b, the photographing lens 2 is controlled to perform focusing.

Although FIG. 7 shows the optical axis as a straight line, in an actual camera, each lens and the like are arranged as shown in FIG.

That is, the photographing light beam incident through the photographing lens 2 is reflected by the main mirror 50 and can be observed by the user 57 through the prism 55 and the eyepiece 56. This portion of the optical path forms a finder optical system.

When the main mirror 50 is retracted from the optical path, an image is formed on the film 53 and photographing is performed.

The main mirror 50 is a half mirror, and the light transmitted through the main mirror 50 is reflected downward through the sub mirror 51. The light beam reflected here is further reflected by the second mirror 52, and the above-described condenser lens 44, mask 45, re-imaging lens 46
Are incident on the sensor arrays 47a and 47b.

When the image signals on the sensor arrays 47a and 47b are detected by the CPU 17 via the A / D converter 22, the focus position is detected based on the above-described principle, and the focus of the photographing lens 2 can be adjusted. Become.

Further, depending on the image signal from the sensor array, the CPU 17 controls the auxiliary light projection by the strobe light emitting section 5 which is a feature of the present invention.

A strobe window 5a is provided in front of the Xe tube 5b, which is a strobe light emitting portion, as an optical system for focusing only infrared light.

Further, if three rows of sensor arrays are prepared, three points in the screen can be measured as in the sensor array 14 of FIG.

As described above, according to the second embodiment, the effective auxiliary light with high contrast is provided at a plurality of points on the screen by the light of the strobe light extending in the length direction of the Xe tube. Light can be projected, and distance measurement shooting without a weak subject can be performed.

Since only infrared light is collected,
A beautiful photograph can be obtained without a trace of the auxiliary light remaining on the photographed photograph.

Next, a third embodiment of the present invention will be described.

FIG. 9A shows a diffractive optical element (Diffract
FIG. 2 is a diagram illustrating an example of a configuration of a strobe light to which an optical element (DOE) is applied.

The diffractive optical element is introduced in "Optics", Vol. 22, pp. 126-130 (Yuzo Ono). SPIE, 1354 (1990)
Year) “Diffractive doublet correctedon-axis at tw
o wavelengths (Michael W, Farn, Joseph W. Goodman)
"And" The design of achromatized hybrid diffrac "
tive lens systems (Camina Londono, Peter P. Clar
k) "and the like, an example in which a diffractive optical element is used for an imaging optical system has been proposed.

In FIG. 9A, the flash tube 6 of the strobe light
In addition, a strobe window 63 is disposed on the subject side of the mirror surface 62 having a light condensing function.

On the object side surface 64 of the strobe window 63, a Fresnel lens for projecting mainly visible light of the strobe light from the strobe light emitting tube 60 and the mirror surface 62 over the entire photographing range is formed. . This Fresnel lens is equivalent to a lens arranged in a conventional flash window, and has a lens function for visible light and infrared light.

On the other hand, the flash tube 6 of the flash window 63
A diffractive lens configured to mainly act on infrared light is disposed on the zero-side surface 65.

The analytical lens and the Fresnel lens 1
02, mainly infrared light of the strobe light from the strobe light emission tube 60 and the mirror surface 62 is
It has the function of projecting light as indicated by 12 shown in (b) and 14 shown in FIG.

FIGS. 9 (b) and 9 (c) show one of FIG. 2 (b).
2 shows an example of the arrangement of diffraction gratings in the case of projecting light, (b) is a front view, and (c) is a cross-sectional view in which a center portion of a surface 65 on the side of the strobe light emitting tube 60 is enlarged. It is.

As shown in FIG. 9C, the diffraction grating 6
5 is desirably formed in a saw-like shape called a kinoform (see Japanese Patent Application Laid-Open No. 7-260677). The height of the serrated peak is substantially constant, and the height is obtained by the following equation.

H = mλ / (n−1) Here, m is a positive integer, and preferably, m = 1.

Λ is the peak wavelength of this diffraction efficiency,
700 nm to 1300 nm is good, and further 900 nm to
1300 nm is preferred. n is the refractive index of the strobe window at the wavelength λ.

FIG. 10 shows the wavelength λ = 1100 nm, m
FIG. 4 is a diagram showing diffraction spectral characteristics when = 1.

FIG. 10 shows how much the diffraction grating receives a lens effect at each wavelength. From this figure, it can be seen that the visible light is hardly affected by the lens action on the surface 65.

FIG. 11 is a diagram showing an example of the arrangement of diffraction gratings when light is projected as shown at 14 in FIG.

As described above, according to the third embodiment, the same effects as those of the above-described second embodiment can be obtained.

Next, referring to FIG. 12, a fourth embodiment of the present invention will be described.
An embodiment will be described.

FIG. 12A shows the configuration of a camera according to the fourth embodiment, and is an external perspective view of a compact camera.

On the front surface of the camera body 70, a photographing lens 2, a finder objective window 3, a distance measuring lens 4, a strobe window 5a, and the like are provided. In addition, a barrier 70a serving also as a power switch is provided on the front surface of the camera body 70.
Are slidably provided. Furthermore, a distance measuring lens 4
Further, a lens 71 with a visible light cut filter is provided adjacent to the strobe window 5a arranged in the base line length direction.

On the upper surface of the camera body 1, there are arranged a release switch 6 and a display section 7 composed of a display LCD.

FIG. 12B is a cross-sectional view of the camera of FIG. 12A cut along a horizontal plane including a finder objective window 3, a distance measuring lens 4, a strobe window 5a and a lens 71 with a visible light cut filter. is there.

The above-mentioned lens 71 with a visible light cut filter
Is composed of a prism-shaped molded part mixed with a dye that transmits infrared light and transmits visible light. Then, the lens 71 with the visible light cut filter
Has a function of condensing light emitted from the end of the xenon discharge tube 5b in a direction orthogonal to the base line length, and a function of changing the direction of the light beam.

As a result, the infrared component 72 having high contrast is superimposed on the uniform light 11 composed of the infrared light for assisting exposure and the visible light projected from the reflector 37 of the strobe. This high-contrast infrared light is invisible to the human eye and is not photographed. However, the sensor arrays 10a and 10b made of silicon photodiodes are sensitive and converted into electric signals. Therefore, by using this contrast, correct distance measurement can be performed even for a low-contrast subject.

When the strobe light is projected onto a low-contrast object, the infrared light contrasts 72a and 72b are transmitted through a pair of light receiving lenses 4a and 4b, as shown in FIG. Incident on. Therefore, the distance measurement based on the principle of the triangular distance measurement can be performed by calculating the position difference of the contrast portion.

As described above, according to the fourth embodiment, a subject having a low contrast can be irradiated with the contrast of the infrared light to enable a correct distance measurement.

Since this contrast is formed by a small prism-shaped optical system provided adjacent to the strobe light-emitting portion without requiring a special light-emitting element, it can be constructed at low cost and in a small space. Can be.

Further, since infrared light has no effect on the exposure and the print, it is possible to take a photograph as before.

Further, since the stroboscopic light emitting section is almost incorporated in recent cameras, it is possible to provide a distance measuring device having a low contrast without increasing the cost.

FIG. 13 is a diagram showing a fifth embodiment of the present invention. In the fifth embodiment, contrary to the above-described fourth embodiment, an infrared light contrast is obtained by using an optical system that does not transmit infrared light.

FIG. 13A is a cross-sectional view showing a strobe light emitting portion and its peripheral portion.

In the same figure, a multi-coat filter 74 having an infrared cut function and a visible light transmitting function is formed in the strobe light projecting window in the form of a cylindrical lens on the front surface of the strobe window 5a. Thus, the infrared component 75 of the strobe light is irradiated non-uniformly. Then, distance measurement is performed based on this contrast, and an effect equivalent to that of the above-described fourth embodiment is to be obtained.

In the fifth embodiment, since the visible light 11 is not cut, it becomes uniform as shown. Then, when the strobe light is projected on the low-contrast object, a pattern (infrared + visible light) 11a as shown in FIG. 13B is formed on the sensor array 10a. This enables triangulation.

In the embodiment described above, the so-called external light type passive triangulation method on the light receiving side has been described. However, the present invention is not limited to this, and can be applied to a contrast AF of a digital camera as shown in FIG.

FIG. 14A is a diagram showing the configuration of such a digital camera.

Therefore, the CPU which controls the camera
The imaging lens 17 is connected to the imaging lens 78 via a focusing unit 19 and the flash unit 5.
Is connected to the xenon discharge tube 5b.

It is assumed that the strobe light emitting section 5 can irradiate only infrared light in a pattern as in the above-described embodiment.

In such a configuration, when an image of a low-contrast subject 79 is taken, the infrared light pattern 80 projected here
8 is formed as an image pattern 80a. Therefore, the sharpness of the image formed on the image sensor 78 is detected while the focus of the photographing lens 2 is controlled by the CPU 17 via the focusing unit 19. This type of AF performs focusing on a position where the result with the highest contrast is obtained.

At this time, on the image pickup device 78, FIG.
As shown in (b), a sensor IR that detects only infrared light is disposed at a predetermined location. As shown in FIG. 14C, R, G, and B filters having a predetermined sensitivity are generally mounted on the image sensor 78. In this example, an IR filter is additionally mounted. Have been.

It is needless to say that, at the time of reproducing an image, the IR pixel is interpolated by an adjacent pixel so as not to reproduce an infrared image.

As described above, according to such a configuration, even in a digital camera, even in a low-contrast scene where distance measurement has been difficult in the past, accurate focusing is achieved by the contrast AF. be able to.

According to the above embodiment of the present invention,
The following configuration can be obtained.

(1) A distance measuring optical system, a pair of sensor arrays for detecting a subject image via the distance measuring optical system, and outputting a pair of image signals, and a strobe light by causing a discharge arc tube to emit light. A strobe means for irradiating, a projecting means for condensing and projecting a part of the strobe light so as to be orthogonal to a longitudinal direction of the sensor array, and a light source for irradiating the subject with the strobe light. A camera for focusing on a photographing lens based on outputs of the pair of sensor arrays.

(2) The camera according to (1), wherein a part of the strobe light focused by the light projecting means is infrared light.

(3) The camera according to (1), wherein the pair of sensor arrays are arranged in a direction substantially coincident with a direction in which the strobe light is collected.

(4) A part of the strobe light is irradiated onto the subject by an optical system with a visible light cut filter provided adjacent to the strobe reflector. The camera according to.

(5) The camera according to (1), wherein the sensor array is constituted by a part of an image sensor of an electronic camera.

(6) A distance measuring optical system, a sensor array for detecting an image of a subject via the distance measuring optical system, and outputting a pair of image signals, and a discharge arc tube. A camera comprising: strobe means for emitting strobe light by emitting light; and focusing means for focusing a photographic lens based on an output of the sensor array when the subject is irradiated with the strobe light. And
A camera, comprising: an optical unit that makes an infrared component of the strobe light irradiated on the subject into a pattern shape, and makes a visible light component of the strobe light irradiated on the subject uniform.

[0114]

As described above, according to the present invention, no additional auxiliary light source is required, and by using the strobe built in most cameras, even in a dark place or a low-contrast subject, a high contrast can be obtained. A camera capable of performing focusing with high accuracy can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electric system of a main part of a compact camera according to a first embodiment of the present invention.

FIGS. 2A and 2B show a configuration of a camera according to a first embodiment of the present invention, wherein FIG. 2A is an external perspective view of a compact camera, and FIG. It is a figure showing a relation.

FIG. 3 is a diagram for explaining the reason why three pairs of sensor arrays are provided.

FIG. 4 is a flowchart illustrating a control operation performed by a CPU 17 when measuring a distance of a camera.

FIG. 5 is a diagram showing details of a photocurrent integration unit of a sensor output for image detection.

FIGS. 6A and 6B show an example of the configuration of a strobe light emitting section 5 in the first embodiment, wherein FIG. 6A is a sectional view, FIG. 6B is a perspective view, and FIG. FIG. 3 is a diagram illustrating an example of incident light.

FIG. 7 shows a second embodiment of the present invention, and is a cross-sectional view of an optical system.

FIG. 8 is a diagram showing an example of a lens arrangement in an actual camera according to the second embodiment.

9A is a diagram illustrating an example of a configuration of a strobe light to which a diffractive optical element is applied, and FIGS. 9B and 9C are diagrams illustrating FIGS.
(B) shows an example of the arrangement of diffraction gratings in the case of projecting light as shown in (12). (B) is a front view, and (c) shows the center part of the surface 65 on the side of the strobe light emitting tube 60. It is the expanded sectional view.

FIG. 10 is a graph showing a formula h = mλ / (n−1) for calculating a height h of a sawtooth peak of a diffraction grating 65 having a sawtooth shape called a kinoform shown in FIG. 9C. FIG. 3 is a diagram showing diffraction spectral characteristics when a peak wavelength of diffraction efficiency λ = 1100 nm and m = 1.

FIG. 11 is a diagram showing an example of the arrangement of diffraction gratings when light is projected as indicated by 14 in FIG.

FIGS. 12A and 12B are views for explaining a fourth embodiment of the present invention, wherein FIG. 12A is an external perspective view of a compact camera according to the fourth embodiment, and FIG. FIG. 2 is a cross-sectional view cut along a horizontal plane including an objective window 3, a distance measuring lens 4, a strobe window 5a, and a lens 71 with a visible light cut filter.

FIGS. 13A and 13B show a fifth embodiment of the present invention, in which FIG. 13A is a cross-sectional view showing a strobe light emitting portion and its peripheral portion, and FIG. 13B is a cross-sectional view of strobe light according to the fifth embodiment. It is a figure showing a pattern.

FIG. 14 (a) is a contrast equation A of a digital camera.
FIG. 4B is a block diagram illustrating F, and FIG.
8C is a diagram illustrating an example of a sensor IR disposed on the image sensor 8, and FIG. 9C is a diagram illustrating sensitivity characteristics of a filter mounted on the image sensor 78.

[Explanation of symbols]

 Reference Signs List 1 camera body, 2 photographing lens, 3 finder objective window, 4a, 4b light receiving lens, 5 strobe light emitting unit, 5a strobe window, 5b xenon discharge tube (Xe tube), 6 release switch, 7 display unit, 10a, 10b sensor array , 11 visible light, 12 infrared light, 14C, 14L, 14R subject detection area, 17 CPU, 18 shutter unit, 19 focusing unit, 20 EEPROM, 21 distance measuring device, 22 A / D conversion unit, 23 stationary light removal Circuit, 25 subjects.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 15/05 G02B 7/11 C 19/02 G03B 3/00 A (72) Inventor Masataka Ide Shibuya, Tokyo 2-43-2 Hatagaya, Ward F-term in Olympus Optical Co., Ltd. (reference) 2F112 AC03 BA07 CA02 EA05 FA03 FA07 GA01 2H011 BA23 BB03 DA08 2H051 BA03 BA17 BA20 CC03 CC11 CC18 2H053 CA08 CA12 2H054 AA01

Claims (6)

[Claims] 1. A distance measuring optical system, a sensor array for detecting an image of a subject via the distance measuring optical system, and outputting a pair of image signals, and a discharge arc tube, which emits light. A strobe means for irradiating strobe light by causing the light to emit light; a light projecting means for condensing a part of the strobe light in a direction orthogonal to a longitudinal direction of the sensor array; A camera which focuses on a photographic lens based on an output of the sensor array when light is irradiated. 2. The camera according to claim 1, wherein a part of the strobe light focused by the light projecting means is infrared light. 3. The camera according to claim 1, wherein the sensor arrays are arranged in a direction substantially coincident with a direction in which the strobe light is collected. 4. The apparatus according to claim 2, wherein a part of the strobe light is irradiated on the subject by an optical system with a visible light cut filter provided adjacent to the strobe reflector. Camera. 5. The camera according to claim 1, wherein the sensor array is constituted by a part of an image sensor of an electronic camera. 6. A distance measuring optical system, a sensor array for detecting an image of a subject via the distance measuring optical system, and outputting a pair of image signals, and a discharge arc tube, wherein the discharge arc tube emits light. And a focusing means for focusing a photographing lens based on the output of the sensor array when the subject is irradiated with the strobe light. A strobe means for irradiating the object with strobe light having a pattern-like infrared component and a uniform-irradiation visible light component;