JPS61138222A - Illuminating device of camera having t.t.l. focus detector - Google Patents

Abstract

PURPOSE:To illuminate efficiently a subject from a near to remote distance by illuminating the subject with two projecting luminous fluxes if the subject exists at the remote distance and illuminating the subject with a part of the projecting luminous flux if the subject exists at the near distance. CONSTITUTION:The 1st and 2nd projecting optical systems 7, 7a, 11, 9, 8, 8a, 12, 10 are disposed apart at a prescribed base line length from the optical axis of a photographing lens in the 1st prescribed direction in a camera having a TTL focus detector set with a focus detecting area on the optical axis of the photographing lens. The spreading angle of the 2nd projecting luminous flux from the 2nd projecting optical system is made larger than the spreading angle of the 1st projecting luminous flux from the 1st projecting optical system with respect to at least the 1st prescribed direction. The 1st and 2nd projecting luminous fluxes are superposed on each other at the 1st prescribed distance or further with respect to the 2nd prescribed direction intersecting orthogonally with the 1st prescribed direction. The 2nd projecting luminous flux is projected to enclose the focus detecting area at the 2nd prescribed remote distance or further and the 1st projecting luminous flux is projected to enclose said area at the 3rd prescribed remote distance or further.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an interchangeable lens camera equipped with a T, T, L focus detection device that detects the focus adjustment state of a photographic lens using light passing through the photographic lens. The present invention relates to an illumination device used to project auxiliary light to assist focus detection.

2. Description of the Related Art Various types of T, T, and L focus detection devices for cameras that detect the focus adjustment state of a photographic lens using light passing through the photographic lens are already known. Publication No. 52-95221 and Japanese Patent Application Laid-open No. 54-15
There are a phase difference detection method as shown in Japanese Patent Laid-open No. 9259, a contrast detection method as shown in Japanese Patent Laid-Open No. 155308/1980, and the like. Generally, when using a T, T, or L type focus detection device, there is a drawback that focus detection is difficult or impossible when the subject is dark or the contrast of the subject is low. Projection is used to illuminate the subject and assist focus detection, for example, as disclosed in U.S. Pat.
An example is shown in Japanese Patent No.-73709.

Problems to be Solved by the Invention When putting into practical use a focus detection system that uses auxiliary light from an illumination device as described above, there are various problems that need to be considered. The problem is how to efficiently illuminate objects at long distances. In particular, in the case of interchangeable lens cameras such as general single-lens reflex cameras, high focus detection accuracy is required, and a variety of interchangeable lenses are used, from ultra-wide-angle to super-telephoto. It is required that focus detection be possible over a wide distance range.

For this reason, lighting devices used in interchangeable lens cameras illuminate a wide range of distances from near to far while encompassing a focus detection area with a spread pt that depends on the angle of view of the interchangeable lens attached to the camera. It is required that it is possible. Currently, if you want to lengthen the distance of the subject that can be illuminated, you can increase the light-gathering ability of the projection optical system and reduce the spread of the illumination light. Unless the light is projected from inside the camera along its optical axis through a lens, it will not be possible to illuminate objects from both near and far distances. On the contrary, if the light-gathering ability of the projection optical system is reduced and the spread of illumination light is increased, the illuminated object area will be expanded, but the illuminated object distance will be shortened. In addition, by increasing the light source power of the projection optical system, it is possible to expand the illuminated subject area and illuminate a long distance, but this requires a large-capacity light source and increases power consumption, making it difficult for the camera to This is not preferable as a lighting device.

The illumination device disclosed in the above-mentioned US Pat. No. 4,150,888 changes the angle that the projection optical axis makes with respect to the optical axis of the photographic lens in conjunction with the extension of the photographic lens for focus adjustment. The projection optical system is configured to rotate and oscillate. With this configuration, it is possible to illuminate objects from short distances to long distances according to the extension of the photographic lens, and by increasing the light-gathering ability of the projection optical system, it is also possible to extend the distance of objects that can be illuminated. However, in this case, the area of the subject that can be illuminated becomes narrower, and if the position of the photographic lens is far off from the subject to be focused, the illumination light will not hit the subject and focus detection will not be possible. Furthermore, in order to rotate and oscillate the projection optical system as described above, a mechanical interlocking mechanism that interlocks the extension of the photographing lens is essential, which not only complicates the structure, but also
Even if an attempt was made to apply this to an interchangeable lens camera, it would be difficult to provide such an interlocking mechanism, and it would be impractical.

On the other hand, in the illumination device disclosed in JP-A No. 57-73709, the projection optical system is disposed within the interchangeable lens barrel, and this projection optical system is linked to the extension of the photographic lens for focus adjustment. Rotate and oscillate. This illumination device eliminates the above-mentioned drawbacks of the illumination device disclosed in U.S. Pat. All of the drawbacks remain unresolved, and a new drawback arises in that a projection optical system must be provided for each interchangeable lens, making the interchangeable lenses expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an illumination device capable of efficiently illuminating objects from short distances to long distances in order to solve the above-mentioned drawbacks of the prior art and to assist in focus detection. .

Means and Function for Solving the Problems The illumination device of the present invention is provided with first and second projection optical systems at positions separated by a predetermined base line in a first predetermined direction from the optical axis of the photographing lens. At least with respect to the first predetermined direction, the spread angle of the first projection light beam from the second projection optical system is set to be larger than the spread angle of the first projection light beam from the first projection optical system. The first projection light beam is included within the second projection light beam. On the other hand, regarding a second predetermined direction orthogonal to the first predetermined direction, the first and second projection light beams are superimposed on each other at a distance beyond the first predetermined distance. Furthermore, beyond a second predetermined distance that is farther than the first predetermined distance, the second projected light beam includes the spread of the focus detection area, and beyond a third predetermined distance that is farther than the second predetermined distance. , the first projection light beam also includes the spread of the focus detection area. Therefore, the focus detection area on the subject that is beyond the third predetermined distance is illuminated by both the first and second projected light beams, whereas the focus detection area is between the second predetermined distance and the third predetermined distance. The focus detection area on the subject is illuminated by only the second projection light beam, or by a portion of the first projection light beam and the second projection light beam.

Embodiments Below, embodiments of the present invention will be described with reference to the drawings. 1 to 6 show a first embodiment in which the illumination device of the present invention is applied to an electronic flash device for 7-shot photography. 19th
7! In FIG. 1, which shows an outline of the entire focus detection system using the illumination device of the example, (C) C main mirror (Mi)
- An interchangeable lens camera configured as an ocular reflex camera, (EL).

(S) indicates an interchangeable lens and a lighting device attached to this camera, respectively. The lighting device (S) is a camera (C)
The accessory shoe (2) provided on the top of the
4), together with a known flash light emitting flash tube (6), a light emitting device (7) (8), a pair of projection lenses (9) (IQ), a pair of projection pattern films (11) ( 12) and the like. In addition, the illumination device (S) is provided with circuits for emitting light such as a well-known booster circuit, a main capacitor, a trigger circuit, etc., and in addition to this, a light emitting device (7). , (8) is provided. The circuit for lighting up the light emitting devices (7) and (8) may be any circuit that can light up the light emitting devices (7) and (8) as necessary prior to the exposure operation during the focus detection operation of the camera. The details thereof are not related to the gist of the present invention, so the explanation will be omitted. The camera (C) has a main mirror (M) and a secondary mirror (Mz), and the subject light that has passed through the photographing lens (14) of the interchangeable lens (EL) is reflected from the main mirror (Ml).
), is reflected downward by the sub mirror (Mz), and enters the focus detection device (D).

2 and 3 show an example of the optical system of the camera (C) and the focus detection optical system in the focus detection device (D) in FIG. 1. In Fig. 2, (16) is a field mask (16) that regulates the focus detection area formed in the main body of the device;
8) C condenser lens, (20) is a mirror for optical path bending, (21) and (22) are a pair of re-imaging lenses, (
Reference numeral 24) is a self-scanning light-receiving element composed of a charge accumulation type (integration type) non-light receiving element such as a CCD. Figure 3, which is a developed view of the focus detection optical system composed of these optical members, shows the principle of focus detection using the phase difference detection method using this optical system, and (26) is equivalent to the film image (28). (30) A condenser lens (18) and a pair of re-imaging lenses (21)
) (22) is a surface that is conjugate with the intended imaging surface (26) with respect to the reimaging optical system. Front focus image (A), in-focus image (B), and rear focus image (
C) The first and second 411 (AI
') (A2'), (Bl') (B'), (C1'X
Cz'), where the distance between the first and second images changes depending on the focusing state of the photographic lens.

As a result, the light receiving element (2) is placed on or near the surface (30).
4) The focus adjustment state of the photographic lens can be detected by arranging the lens t- and determining the distance between the first and second images when they best match based on the output thereof. In addition, in Fig. 3, (32) is the photographing lens (1
4), the optical axis (34) is an aperture mask that forms a pair of aperture apertures just in front of the re-imaging lens (21×22).

FIG. 4 is a plan view specifically showing the projection optical system of FIG. 1, in which the projection lenses (9) and (10) are arranged with a distance D between their centers. The light emitting devices (7) and (8) each have a light emitting diode inside and a projection lens (9).
The focal position of (10) is also located a little behind (on the left side in the figure) so that the center is shifted outward by d from the optical axis of projection lenses (9) and (10), and at the tip of each Widths φA and φB with radii R1p and R2 (Rt < R2), respectively.
Spherical light condensing parts (7a) (8a) are formed. In addition, the projection pattern films (11) (12) are connected to the projection lenses (9) (10) immediately in front of the spherical condensing parts (7a) (8a).
), and the patterns to be described later are accurately positioned and arranged so that they do not deviate from each other. Light emitting device (
7) The spherical condensing part (7, a) (8a) in (8) is a condenser for condensing the luminous flux emitted from the internal light emitting diode within the effective diameter of the projection lens (9) (10). Since R1<R2, the projection lens (10
) projects a light beam that spreads at a wider angle than the light beam projected from the projection lens (9). That is, when comparing a first projection optical system consisting of a light emitting device (7) and a projection lens (9) with a second projection optical system consisting of a light emitting device (8) and a projection lens (10), the first projection optical system consists of a light emitting device (8) and a projection lens (10). The optical system is set to have a higher light gathering ability than the second projection optical system.

In Figures 5 and 6, which show the spread of the light flux projected from the first and second projection optical systems, the solid line is the light flux projected from the first projection optical system, and the broken line is the light flux projected from the second projection optical system. The shaded area is the field mask (1
6) is the spread of the focus detection area of the focus detection device (D) regulated by. As shown in FIGS. 4 and 5, the projection optical axes (36) (38) of the first and second projection optical systems are located at a predetermined distance L=3 m when viewed in the vertical direction, and the photographing lens optical axis ( 32), and when viewed in the horizontal direction, as shown in FIG. 6, they overlap with the photographing lens optical axis (32) at distances of 3 m, x, and 8 m, respectively. In other words, the two projection optical axes (36) and (38) extend in a manner that twists each other.
7) Making the vertical distance from the optical axis of (8) to the optical axis of projection lenses (9) and (10) or the inclination in the vertical direction of the entire first and second projection optical systems including them different from each other. given by. In addition, as shown in FIG. 6, the spread of the luminous flux from the first and second projection optical systems is as follows:
At the upper end, the two light beams almost overlap each other, and at the lower end, the two light beams are set to have a large deviation. For example, in the illustrated example, in the vertical direction, the light beam from the first projection optical system begins to overlap the photographing lens optical axis (32) at about 1.4 m, and includes the focus detection area at about 1.8 m or more. On the other hand, the luminous flux from the second projection optical system starts to overlap the optical axis (32) of the photographic lens at approximately o, sm, and is approximately 0.97
ff or more includes the focus detection area. On the other hand, in the horizontal direction, as shown in Fig. 5, the luminous flux from the first projection optical system is about 0.5 m, and the optical axis of the photographing lens (3
2) and covers the focus detection area at about 1.8 m, whereas the light flux from the second projection optical system is about 0.8 m.
At 3 m, it starts to overlap with the optical axis of the photographing lens (32), and at about 0.01 m.
8 m includes the focus detection area. From the above, in the case of the illustrated example, the two light beams from the first and second projection optical systems will completely overlap each other and illuminate the focus detection area at a distance of approximately 1.8 m or more, and approximately 0.9 m From about 1.87
In the range of 7J, only the light beam from the second projection optical system, or the light beam from the second projection optical system and part of the light beam from the first projection optical system illuminates the focus detection area.

The above-mentioned distance is the distance at which the projected image of the projection pattern of the projection pattern film (11) (12) forms the sharpest image, as described later, and the two projected images are formed at this distance. overlap completely.

By the way, when the optical axis of the projection lens is placed at a distance m (hereinafter referred to as the base line length) directly above the optical axis of the photographing lens, the illumination is caused by the light flux projected by the projection lens. The possible distance range on the optical axis of the photographing lens (hereinafter referred to as the possible illumination distance range) is determined by the base line length m, the degree of spread of the luminous flux projected from the projection lens, and the projected light of the entire projection optical system including the projection lens. It is determined by the angle θ at which the axis intersects with the optical axis of the photographing lens, the distance to the focal point of the projection lens, etc., and the extent of the device consisting of the projection lens is determined by the diameter of the light source as φ and the focal length of the projection lens as if. When f
/φ. FIG. 7 shows '/φ=7.
2. When L = 5 m, how the illumination distance range changes depending on the value of θ is expressed as m
In the graphs shown when =80H and when m=1QQjl11, the solid line represents the case when m=80ff, and the broken line represents the case when 11=lQQl'1g. As shown in this graph, as θ increases, the entire illumination possible distance range moves toward the shorter distance side, and even when m decreases, the entire illumination possible distance range moves toward the shorter distance side. Note that the focus detectable distance range in which focus detection is possible is a range in which the focus detection area is included in the projection light beam from the projection optical system, and does not coincide with the illumination possible distance range. However, when the illumination possible distance range moves to the short distance side, the focus detectable distance range moves to the short distance side, and when it moves to the long distance side, it also moves to the long distance side.

Therefore, the tendency of change in the illumination possible distance range shown in the graph of FIG. 7 also applies to the focus detectable distance range. However, in order for focus detection to be possible, the subject illuminated by the projected light beam must have a brightness level higher than that level, so as long as the brightness of the light source is finite, the actual focus detection distance is The maximum distance of range is limited by the brightness of the light source.

On the other hand, as in the above-described embodiment, the illumination device (S) having the first and second projection optical systems can be connected to the camera (C ), it is difficult to avoid mechanical coupling play, which changes the direction of the projection optical axes (36) (38) of the first and second projection optical systems.

This change in the projection optical axis appears, for example, in the vertical direction as a deflection of the projected light beam as shown by the angle 〃 in Figure 6 (the two-dot chain line indicates the projection light flux from the projection optical system that is deflected due to the coupling play, and the three-dot chain line indicates the deviation of the projection light beam from the projection optical system). (This shows the projected light flux from the second projection optical system that fluctuates due to coupling play).This fluctuation of the projected light flux naturally affects the focus detectable distance range, but the degree of influence is generally greater on the far side than on the near side. So big. However, as in the above embodiment, the upper limits of the projected light beams from the first and second projection optical systems are set so that they almost overlap each other, and the upper limits of the projected light fluxes from the first and second projection optical systems are set so that they intersect with the focus detection area at a farther distance. (see FIG. 6), the focus detectable range is limited by the brightness of the light source on the long distance side, so the influence of fluctuations in the projected light beam can actually be relatively small.

Figures 8(A) and 8(B) show 1 in the case of the above embodiment.
, 07ff and 5.0 m, respectively, show the relationship between the overlap of the projection light beams from the eleventh and second projection optical systems and the focus detection area. In the figure, (Ll) (L2)
(E) shows the cross section of the projection light beam from the first and second projection optical systems, and (E) shows the focus detection area. However, in this figure, the relationship between the beam cross section (LL) (L2) and the focus detection area (E) is drawn based on the beam cross section side, and the relationship between the illumination device (S), force, and camera (C) is Due to the coupling play, the focus detection area (E) moves relative to the beam cross section (LL) (L2) within the range shown by the broken line in the figure.

The first embodiment has been described above, but in the first embodiment,
As shown in FIGS. 8(A) and 8(B), the projection light flux from the second projection optical system for illuminating a short distance is transmitted to the illumination device (
Even when considering the coupling play between S) and camera (C), the beam spreads out more than necessary in the horizontal direction9, and the portion of the light beam that deviates from the focus detection area (E) to the left and right is used to illuminate the focus detection area. It means you are not contributing anything. FIG. 9 shows a projection optical system according to a second embodiment of the present invention, which can further improve illumination efficiency by reducing such a wasted portion of light flux.

In Fig. 9, (107) and (108) are light emitting devices that have light emitting diodes inside, and the light transmitting parts (107a) and (108a) of these light emitting devices are formed into spherical surfaces with the same radius. . The first and second projection lenses (109) and (110) also have the same focal length, and a projection pattern film (11) is located at their focal position.
1) (112) is provided. (140) is a transparent panel placed in front of the projection lenses (109) and (110), and a prism (1
42) is formed. The width of the prism (J 42 ) is relatively narrow in the vertical direction compared to the width of the projected light beam, but
The width in the left and right direction is approximately equal to the width of the projected light beam. Further, the cross-sectional shape of the prism (142) is triangular, as is clear from the figure, and the prism (142) is thicker toward the bottom. The hatched section in the figure is the portion of the projected light beam that passes through the prism (142), and this portion accounts for approximately 10% of the entire light beam projected from the second projection optical system.

In FIG. 10, which shows only the second projection optical system, (144
) (146) are the light rays that pass through the outermost (vertical direction) of the projection lens (110), and after passing through the projection lens, they pass through the flat part of the spring 7v (140).

Since the spring iv (140) is held by a parallel plate at the position through which these light rays pass, the angles of these light rays with respect to the longitudinal direction before and after the spring /v (140) remain unchanged.

On the other hand, (148) and (150) are the rays that pass through the upper and lower ends of the prism (142), and these are the rays that pass through the upper and lower ends of the prism (142).
2)? After passing, it is bent downward by an angle of about 1/2 of the apex angle ψ of the prism.

FIG. 11 shows the optical path of the projection light beams from the first and second projection optical systems in the second embodiment, as seen from the vertical direction,
Projection optical axes of the first and second projection optical systems (136) (13
8) are both crossed with the photographing lens optical axis (132) at a position of 3 m.

FIG. 12 shows that in the second embodiment, the focal length f of the first and second projection lenses (109) (110) is 22mm, and the width φ of the condensing parts (107a) (108a) is 2.4ta+
, the baseline length m is 1Q33+1. The angle ψ is 7°, and the projection optical axes (136) (1
38) is set to intersect with the optical axis of the photographing lens (132) at a distance of 3.2 m when viewed from the horizontal direction. ) 'rThe spread range of the projected light beam that did not pass through, and the focus detection area (E) is approximately 1.2 m or more.
'eIncludes. On the other hand, ray (148) (1
50) is the spread range of the projected light flux that has passed through the prism (142), and is approximately 0.8 m to approximately 1.25 m.
．． The range of 771 includes the extent of the focus detection area (E). FIG. 13 is a cross section of the projected light beam in the second embodiment at a distance of about 2 m, and the portion within the circle (152) is the projected light beam (Ll) that did not pass through the prism (142)'.
) (L2) The portion outside the circle indicated by (154) is the projected light flux (L2') that has passed through the prism (142).

In this second embodiment, the projection lenses (109) (110) ft of the first and second projection optical systems are spread 9
the second projection lens (110) while making the degrees equal to each other;
13 and 8 (A).
As is clear from the comparison with (B), the portion of the light flux that does not contribute to the illumination of the focus detection area (E) is the 19j! The amount can be reduced compared to the example.

In addition, in the second embodiment, the prism (142)
There is a difference in the intensity of the light beam passing through. This is a light emitting device (
This is because the light emitted from the light emitting diode built into the projection lens (108) has strong directivity in the direction of the projection lens optical axis (138), and is condensed by the light condensing section (108a) and directed toward the projection lens (11).
The intensity of the light beam directed toward 0)' increases as it approaches the projection lens optical axis (138). Therefore, the smaller the deviation amount 1''f is, the stronger the intensity of the light beam passing through the prism (142) becomes, and by selecting the deviation amount E, the intensity of this light beam can be appropriately set.

FIG. 14 shows only the main parts of the second projection optical system in the first modification of the second embodiment. In this modification, the prism (142') is tilted at the transparent spring p (140'). It is formed as a surface, and the spring /L/(14
0') is the thickness tl of the two steps across the slope.

Tze Motsu. However, the first of this spring /L/(140')
The portion through which the light beam from the projection lens passes is a parallel flat plate with a thickness tr (or may be t2). Also, in the range shown in the figure, the beam projected by the projection lens (110) is drawn to converge, but this beam once converges near the spring /L'(140') (not shown). After that, it expands again to cover the focus detection area over a wide distance range.

FIG. 15 shows the second projection optical system in the second modification of the second embodiment, in which the spring /l/(140'') is inclined as shown in the figure with respect to the projection optical axis (138). provided p
D, and the prism (142'') formed on the spring /L/(140'') has a cylindrical concave curved surface with a radius R. Since this prism (142'') has a cylindrical concave curved surface, The projected light flux passing through this diverges as shown in the figure, but the intensity of the light flux is strong in the upper part of the figure and weaker in the lower part. Therefore, in the distance range in which the projected light flux includes the focus detection area, weaker illumination is provided at closer distances, and stronger illumination is provided at longer distances, so that illumination efficiency is improved.

Here, in order to further improve the illumination efficiency, a prism (
142''). Note that such a prism (142'') does not interfere with the projection of a projection pattern consisting of vertical stripes, which will be described later.

FIG. 16 shows a third embodiment of the invention. In the case of this embodiment, first, second, and third projection optical systems are provided, but the light emitting device (207
) is shared and is one. In addition, the projection film pattern (
212) is also the first. Since it is shared by the second and third projection optical systems, there is no need to align the two projection film patterns as in the first and second embodiments. In the figure,
(209), (210), and (211) are projection lenses belonging to the first, second, and third projection optical systems, respectively, and are arranged to overlap each other in the vertical direction. (242) and (243) are prisms belonging to the first and third projection optical systems, respectively. These prisms may have a cylindrical concave cross section having a spherical or aspherical curved surface similar to that shown in FIG. In Jin's example, the projection lens (
209) (210) (211) makes the light emitting device (
The luminous flux from the spherical condensing part (207a) of 207) is the first,
It is divided into second and third projection light beams and projected, and among these, the first and third projection light beams are then passed through the prism (242) (2
43) K causes the beam to be refracted in a direction that approaches parallel to the projection optical axis of the projection lens (210). As a result, the first
As shown in FIG. 17, the second and third projection light beams illuminate a long distance area, a middle distance area, and a short distance area, respectively. Here, the spread angles of the first, second, and third projected light beams are set to α1. α2. When α3 is used, projection lens (209)
By making the focal lengths of (210) and (211) different from each other, i.e., α1, α2, and α3, the illumination efficiency can be improved.

Although the illustrated embodiments of the present invention have been explained in detail above, the light source of the projection optical system that illuminates the object and the projection pattern film have not been described in detail.

Therefore, these will be explained in detail below.

First, there are various issues that need to be considered when implementing a focus detection system that uses auxiliary illumination light from a lighting device.
One of these is the improvement of illumination efficiency for subjects from near to far distances, but other issues that should be considered include the selection of the auxiliary illumination light source and the wavelength of the auxiliary illumination light, and the projection pattern. There is a problem of selection. Considering the issue of the auxiliary illumination light source and the wavelength of the auxiliary illumination light, it is desirable to have a light source with low power consumption, and currently a light emitting diode is optimal, but when using a light emitting diode as an auxiliary illumination light source for focus detection, It is necessary to consider the efficiency of converting electrical energy into optical energy, the degree of stimulation of the illumination to the human eye, and the magnitude of the influence of the photographic lens on chromatic aberration. Here, in the case of a light-emitting diode, the efficiency of converting electrical energy into light energy depends on the wavelength of the light emitted by the light-emitting diode, and generally increases as the wavelength becomes longer. On the other hand, if the degree of stimulation to the human eye is large, if the human subject is the subject and the illumination light is projected onto his or her face, it will be dazzling and cause the eyes to bulge, resulting in the disadvantage that the photograph will be taken with the eyes closed. For example, as shown in the example K in Figure 18 (vertical axis is logarithmic value), the degree of stimulation also depends on the wavelength, and tends to decrease as the wavelength increases from near the center of the visible light region to the infrared region. , for example 700
For example, the stimulation is about V1o for 55Q 41m-.

Viewed in this way, it is desirable to use so-called infrared light as auxiliary illumination for focus detection, but in the case of infrared light, the effect on the chromatic aberration of the photographic lens is too large, and the Since it changes greatly depending on changes in focal length and lens extension position, it is difficult to accurately correct the difference in the amount of chromatic aberration between visible light and visible light. Therefore, as an auxiliary illumination light source for focus detection, approximately LPL#! Overall, it can be said that it is most suitable to use a light emitting diode that emits light with a substantially single wavelength of approximately 7QQ#.

However, when using a light emitting diode as a light source, there is another problem. The sensitivity of the light receiving element is approximately 3B64B.
On the other hand, the light emitted by a light-emitting diode is close to monochromatic light and usually only has a spread of about 59mm. There is often a difference in the contrast of an object when viewed through a light-receiving element compared to when it is illuminated with light. In other words, for most objects, the reflectance tends to increase as the wavelength of the light illuminating it increases, and in general, for light around 7QQe, there is no difference in contrast in coloration. Therefore, even if an object has a high contrast under natural light illumination when viewed through a light receiving element, the contrast often decreases under light emitting diode illumination. Figure 19 shows the spectral reflectance of green, glue gray, and white objects as an example, and shows that for light around 7QQs+p, it is greener than for light in the 500 to 600 range, which is the center of the visible light range. The difference in reflectance between the object and the blue-gray object is small. When the contrast of the subject is reduced by fill-in illumination, the focus detection accuracy of T, T, and L focus detection devices generally deteriorates, and in extreme cases, it may become impossible to detect focus, so there is no point in using fill-in illumination. will be gone. In other words, if there is no contrast in the subject, it will be difficult to detect a matching point between the two re-formed images even with the above-mentioned phase difference type jT, T, L focus detection device, so if this problem is left unaddressed, This is a fatal flaw.

In each of the embodiments described above, in order to solve the above problems,
Light emitting device (7) (8) (107) (108) (
207) has a built-in light emitting diode that emits light of approximately a single wavelength of about 700 Tsuru (currently, the most suitable such light emitting diode is the GaAIHAs Taigu light emitting diode, which was recently developed as a light source for optical fiber communication. ), projection lens (9) (10) (1
At the focal position of 09) (110) (209) there is a projection pattern film (11) (12) (111) (11
2) (211) was installed.

FIG. 21 shows examples of projection pattern films (11) (12) used in the above embodiments. This film has a projection pattern consisting of vertical stripes), with the hatched area being the opaque area and the remaining area being transparent. If the width of the opaque part is p and the width of the transparent part is q, then p
and q are different from each other in each opaque part and transparent part9, and the repetition period (p+q) is also completely irregular. These films, as shown in FIG. 9) (10,) projects the image of its projection pattern onto the subject, and as mentioned above, even if the contrast on the subject becomes small due to the illumination with light from the light emitting diode of approximately single wavelength, the image of the projection pattern on the subject is Create contrast using the projected pattern image. The contrast created in this manner solves the problem in which focus detection is difficult or impossible in T, T, and L focus detection devices, and makes focus detection possible. In addition, film (1
1) Since (12) is close to the focal point of one of the projection lenses (9) and (10), the images of the projection pattern become sharpest at the distance L in Figure 4 and completely overlap each other. overlap.

Incidentally, the width of the opaque portion of the projection pattern of the film mentioned above is determined as follows, taking into consideration the width of one pixel of a focus detection light receiving element, for example, a CCD, in a focus detection device.

Figure 22 shows an image of a projection pattern consisting of a single opaque area projected onto a plain object, viewed from the focus detection plane together with the field frame. For example, one of the two projected pattern images re-imaged on the light-receiving element surface disposed on the surface (30) is displayed in the field frame (26).
It is a diagram shown together with the focus detection area (E) which is an image of the image. In the figure, X is a focus detection light receiving element, such as a CCD.
h is the width of the l cell portion of , and h is the width of the projected pattern image re-imaged on the light receiving element. Now, if x ) h, not only will the signal output of the cell where the projected pattern image is formed become weak, but even if the projected image moves within one cell, the overall output of the light receiving element will not change. Therefore, the position of the projected pattern image on the light receiving element cannot be detected correctly. On the other hand, if X≦h, such a problem will not occur, but if h is too large relative to X, there is a risk that the entire focus detection area will be occupied by the projected pattern image, which is undesirable. In addition, aberrations of the photographing lens and blurring of the projected pattern image on the light receiving element surface according to the focus adjustment state expand the width of the projected pattern image by h''f, and increase the output difference between adjacent cells in the light receiving element. In order to make it smaller and make it difficult to detect coincidence between two projection pattern images, h is kept in the range of 3h≧X≧h/2 in the focused state, and multiple projection pattern images are always within the focus detection area. Relatively favorable results can be obtained by allowing the formation of However, the width of the projected pattern image on the focus detection plane depends on the angle of view of the photographing lens, for example, the interchangeable lens (E
9. Compared to standard lenses, wide-angle lenses are narrower while telephoto lenses are wider, but the above conditions must be met for all angles of view of the interchangeable lenses you plan to use. It is preferable to take care to ensure that they are satisfied. On the other hand, if a plurality of opaque parts with the same width are provided in the projection pattern, in the case of the phase difference type focus detection device shown in FIG.
A plurality of sets of matching projection pattern images are detected, leading to incorrect focus detection. Further, in a wide-angle lens, the focus detection area is relatively large, and if the same pattern is repeated in the projection pattern, they will fit together within the focus detection area, causing focus detection errors as described above. Therefore, in the projection pattern of the projection pattern film described above, not only the width p of the opaque part but also the repetition period (p+q) of the opaque part and the transparent part are arranged completely irregularly. In this way, the width and arrangement of the opaque parts in the projection pattern film described above are determined. However, when the illumination device (S) is coupled to the camera (C) by mechanical coupling means as in the above embodiment, the opaque parts The number of lights in the lighting device (S
) in the camera (C), where there is no need to consider connection play, it is appropriate to increase the number of holes.

In the case of the projection pattern in the projection pattern film of FIG. 20, the narrow opaque parts are arranged at relatively narrow intervals, and the wide opaque parts are arranged at relatively wide intervals. As a result, coincidence detection of the two images formed by the re-imaging lenses (21) and (22) is performed based on the projected image of the narrow opaque area when the focus detection area is relatively narrow, such as with a telephoto lens. When the focus detection area is relatively wide as in the case of a wide-angle lens, the detection can be performed mainly based on the projected image of a wide opaque area, and the focal point due to the difference in the angle of view of the photographic lens can be used. The influence on detection performance lPt can be minimized.

FIG. 22 shows a modified embodiment of the projection pattern film of FIG. 20. Also in this modified embodiment, the width p1q of each opaque part and transparent part of the projection pattern is different from each other, and
The period (p+q) is also irregular.

In addition, in the above-mentioned two projection pattern films, the opaque parts at both ends have overhanging parts (at) (all) (
aa) is formed, but the overhanging part (al) is located at a vertically intermediate position between the overhanging parts (a2) and (aa),
By using these projecting portions on the projected image, the projection pattern film can be positioned in the eleventh and second projection optical systems.

FIG. 23 is a plan view showing the overlapping range of projection pattern images when projection pattern films are arranged in the first and second projection optical systems as shown in FIG. To simplify the explanation, each projection pattern consists of a single opaque part with a width p at a position a distance outward from the optical axis center of each projection lens in the horizontal direction, as shown in FIG. Suppose you are prepared.

Further, let f be the focal length and aperture of each projection lens, D be the distance between the optical axes of the two projection lenses, and L be the distance at which the projected images of the two patterns perfectly match. Now, in order to determine the degree of overlap between the projected images of the two patterns before and after the position of the distance, the distances LMIN and LMAX at which the overlapping area of both patterns is 1/2 in each projected image are determined. Taking the coordinate xi from the projection lens position forward in parallel to the optical axis direction of the projection lens, and taking the y coordinate from the optical axis of one projection lens in the direction perpendicular to the X coordinate on the horizontal plane,... (3) (4) However, b<L, and Ymax and ymin each represent the endmost light Me of the projected pattern light flux by one of the projection lenses. On the other hand, the light ray at the center of the projected pattern light beam is y=−−x ・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
... is expressed as (5). Here, the condition that the two projection pattern light beams are more than half the size of each other is as follows: When X≧L, y+ymt. ≧D・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・(6) In xkuL, y+ya, ≧D ・・・・・・・・・Song・・・・・・・Song・
Since it can be assumed that music, music, etc. is 4 (7), (2) (s> (6) can be obtained from equation (6).

For example, [, == 3m, f == 181ff,
l := Q, lfl, b” 81jnll,
If D = 29sor, then (8) and (9), F) LMA! = 5.1 Wl, LMIN =
1.7 m, and if only D is changed to D=15jllf, LMAX = 6.4 m, LMIN = 1
．． 4 Wl.

Also, if only p is changed to 0.12m, LMAX = 6
．． 0 m.

LMIN = 1.6 m. From this, it can be seen that by decreasing the distance Dt between the two projection lenses or increasing the projection pattern width δ, the degree of overlap between the two projection pattern images can be maintained at 1f2 or more over a wider range.

Note that when the degree of overlap between the two projection patterns decreases,
The contrast of the projected pattern image on the subject becomes correspondingly lower, and it becomes difficult to detect coincidence between the two images formed by the re-imaging lens on the surface of the focus detection light receiving element. One guideline for detecting the coincidence without any problems in practice is that the degree of overlap between the two projection patterns is 1/2 or more, and
This condition is stricter on the short distance side than on the long distance side (the range of distance based on the distance point is narrower on the short distance side than on the long distance side). However, on the short distance side, the intensity of the projected light beam is strong, and as a result, the degree of overlap between the two projected pattern images is 1/1.
Even if it is smaller than 2, the contrast of the projected pattern image on the subject tends to remain relatively high.
In fact, focus detection is possible even at a distance shorter than LMIN given by equation (9).

Figures 25(A) and 25(B) show that the distance Di This figure shows the structure of a compound projection lens that can be made small. That is, in this configuration, two sheets are placed on one transparent plate (300) made of synthetic resin.
Two projection lenses (309) (310) are integrally molded, but the two projection lenses (309) (310) touch each other at the boundary (312), and when the radius is r, the distance between them is ri is Dku2r.

Although the illustrated embodiments have been described above, the present invention is not limited to the above-described embodiments.

For example, in the case of the above embodiment, the illumination device (S) was provided as an electronic flash device for flash photography, but is the illumination device (S) separate from the electronic flash device? It may be provided alone. In addition, the lighting device (S) is not only an accessory shoe for the camera, but also a
The camera may be provided with a suitable mounting part and the mounting part may be mounted there, or it may be fixedly mounted on the camera. In that case, the position of the illumination device relative to the camera's photographic lens is preferably directly above, directly below, or to the side of the photographic lens, since the focus detection area generally extends in the horizontal and vertical directions. There is no need to limit it to this.

Effects As explained above, in the lighting device of the present invention, when the subject is far away, the focus detection area on the subject is set as the first focus detection area.
If the object is illuminated with both the first and second projection light beams from the second projection optical system, and the subject is at a short distance, the focus detection area on it is illuminated with only the second projection light beam or the second projection light beam. Since the illumination is performed using a part of the first projection light beam, it is possible to efficiently provide illumination for focus detection to objects from short distances to long distances. Furthermore, since the first and second projection optical systems need only be fixedly installed in the illumination device, there is no drawback of the prior art described above, and the focus detection aid for a lens-interchangeable camera having T, T, and L focus detection devices is eliminated. Ideal as a lighting device.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the entire focus detection system using the illumination device according to the first embodiment of the present invention, FIG. 2 is a diagram showing the focus detection optical system in the focus detection system of FIG. FIG. 2 is a developed view of the optical system showing the principle of focus detection by the focus detection optical system, and FIG.
A plan view of the second projection optical system, FIGS. 5 and 6 are a horizontal plan view and a side view based on the relationship between the projection light flux from the first and second projection optical systems and the focus detection area in FIG. 4, Figure 7 is a graph showing the relationship between the angle that the projection optical axis makes with respect to the optical axis of the photographing lens and the possible illumination distance range, and Figures 8 (A) and (B) are the first, A diagram showing the overlapping state of the projection light beams from the second projection optical system and the relationship between them and the focus detection area, FIG. 9 is a diagram showing the first and second projection optical systems of the illumination device in the second embodiment of the present invention. Perspective view of No. 10
The figure is a side view of the second projection optical system in FIG. 9, and FIGS. 11 and 12 are planes showing the relationship between the projection light fluxes from the first and second projection optical systems in FIG. 9 and the focus detection area. The figure and the side view, Fig. 13, show the first and second
14 and 15 are diagrams showing the overlapping state of the projected light beams from the projection optical system and the relationship between them and the focus detection area, respectively. Side view of the optical system, Figures 16 and 18 are diagrams showing the relationship between relative illuminance (stimulation to the eyes) and wavelength, Figure 19 is green,
Glue gray, diagram showing the spectral reflectance of a white object, No. 20
The figure is a plan view showing an example of a projection pattern film.
The illustration is of a plain old woman. FIG. 22 is a diagram showing a projected pattern image consisting of a single opaque portion projected onto an object, viewed from the focus detection plane together with the field frame.
The figure is a plan view showing another example of the projection pattern film.
Fig. 3 is a diagram showing the overlapping range of two projection pattern images when the projection pattern films are arranged in the first and second projection optical systems as shown in Fig. 4, and Fig. 24 shows the projection lens in Fig. 23. FIGS. 25(A) and 25(B), which show the positional relationship of the projection pattern with respect to the optical axis, are a plan view and a side view of the first and second projection lenses integrally formed as a composite projection lens. projection optical system, (8) (8a) (10) (12)
i (108) (108a) (110) (112
) i (108) (108a) (110) (1
12) (142) 1(108) (108a) (
110) (112) (142'); (108)
(108a) (110) (112) (142”)
i (207) (210) (212)...Second
projection optical system, (2) (4)... mechanical coupling means,
(E)... Focus detection area, (S)... Illumination device,
(C)...Camera, (F)...Focus detection device. Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 3 (Pano (B) Fig. 9 Fig. 10 Fig. 11 Fig. 114t2 Fig. 24 r Fig. t5

Claims (1)

[Claims] 1. T with a focus detection area set on the optical axis of the photographing lens
．． T. In an illumination device for a camera having an L focus detection device, the first and second projection optical systems are arranged in the first direction from the optical axis of the photographing lens.
are arranged at a predetermined baseline length in a predetermined direction, and at least in this first predetermined direction, the spread angle of the second projection light beam from the second projection optical system is set to The spread angle of the first projected light flux is set to be larger than the spread angle of the first projected light flux so that the first projected light flux is included in the second projected light flux, and the second predetermined direction orthogonal to the first predetermined direction is
, the second projected light beams are overlapped with each other at a distance beyond the first predetermined distance, and at a distance beyond the second predetermined distance which is farther than the first predetermined distance, the second projection light beam covers the spread of the focus detection area. An illumination device characterized in that, furthermore, the first projected light beam is configured to include the spread of the focus detection area beyond a third predetermined distance that is farther than the second predetermined distance. 2. The illumination device according to claim 1, wherein the main body of the illumination device in which the first and second projection optical systems are arranged is detachable from the camera by mechanical coupling means. 3. When the illumination device main body is coupled to the camera by the mechanical coupling means, the first and second projection optical systems are configured to be located above the optical axis of the photographic lens, and
3. The lighting device according to claim 2, wherein the second predetermined directions are a vertical direction and a horizontal direction, respectively. 4. Also with respect to the second predetermined direction, the spread angle of the second projected light beam is set to be larger than the spread angle of the first projected light beam.
The illumination device according to any one of items 1 to 3.