JP2002116376A - Floodlight, photographing device and observing device - Google Patents

Abstract

(57) [Summary] With the demand for enlargement of the focus detection area, the projection range of the pattern image must be enlarged while maintaining a good imaging state. SOLUTION: In a light projecting device that projects a pattern image on a subject in order to detect a focus state of a photographing system or an observation system by a phase difference method, a first pattern 4-A extending in a first direction is formed on the subject. A first projection system A that projects at a plurality of positions aligned in the first direction, including a central focus detection area of
A second projection system B for projecting the second pattern 4-B extending in the second direction to a plurality of positions in the second direction including the central focus detection area on the subject is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light projecting device for projecting a pattern image on a subject in order to detect a focus state of a photographing system or an observing system, and a photographing device and an observing device using the same. The present invention relates to a light projecting device suitable for a device for detecting a focus state of a photographing optical system or an observation optical system from a reflected light reception image of a pattern image by a phase difference method.

[0002]

2. Description of the Related Art Among optical devices such as cameras, cine cameras and video cameras, TTL type optical devices have a built-in illumination built into a camera body or a strobe device when the brightness of the subject is low or the contrast of the subject is low. (Light projection) There are devices that illuminate a subject with a device, or project a pattern image onto a subject by incorporating a projection lens and a fixed light projection pattern into an illumination device, and perform focus detection by giving contrast.

FIG. 12 shows the configuration of a projection system in a light projection device of the type which projects a pattern image on a subject. In the figure, reference numeral 104 denotes a light source, for example, an LED
It is composed of 103 is a light projection pattern (mask)
For example, as shown in FIG. 13, a light-shielding portion 103a and a transmissive portion 103b formed of a plurality of linear bands are provided. 102 is a projection lens.

In FIG. 12, of the light from the light source 104, the light transmitted through the transmitting portion 103b of the light projecting pattern 103 is applied to the subject side through the projection lens 102.
Thereby, a pattern image corresponding to the light projection pattern 103 is projected on the subject. Then, the reflected image of the pattern image is received and detected by a phase difference type focus detection system (not shown), and the focus of the imaging system is detected.

FIG. 14 shows an irradiation (illumination) range of projected light and a projected pattern image when a pattern image is projected on a subject. In the figure, the inside of a dotted line portion 121 is an illumination range, and the range indicated by a hatched portion 122 is a pattern image.

In such a light projecting device, the focus detection range of the photographing device to which the light projecting device is attached is often located at the center of the photographing screen (the center of the optical axis of the photographing lens), and the projected light is also parallax Aside from the correction of the above, only the center on the object side is illuminated.

[0007] On the other hand, in recent years, there has been proposed an imaging device for detecting the focus of a plurality of points on a subject. Even in such a case, the above-described pattern image of the fixed pattern is projected on the subject side,
Performing focus detection by detecting a reflection pattern image from a subject is, of course, effective. In addition, not only the focus detection area is arranged in only one of the horizontal direction and the vertical direction in the shooting screen, but also the focus detection areas are arranged in both the horizontal direction and the vertical direction, and two directions are provided at the center of the screen. Have crossed focus detection areas. This is a device for obtaining a good focus detection result without being limited to the contrast direction of the subject.

In a light projecting device used in a photographing apparatus having a plurality of focus detection areas or arranging focus detection areas in two orthogonal directions as described above, the plurality of focus detection areas are formed by a conventional projection system. It is difficult to project a pattern image onto an area at the same time.

In order to simultaneously project a pattern image on a plurality of points, a large pattern image is created in advance and formed in a wide area, or a very fine pattern image having a very short focal length is formed. It is necessary to form an image over a wide range using a projection lens having an angle of view.

However, in any case, in order to form a pattern image on a subject in a satisfactory manner, it is necessary to satisfactorily correct the aberration of the projection lens over a wide angle of view. It is quite difficult to do. In addition, in the above-described method of creating a large pattern image, it is necessary to increase the size of a light source for illuminating the large pattern image, and there is a problem that a compact configuration cannot be achieved.

Further, in the method of forming a pattern image over a wide area by the projection lens having an extremely short focal length as described above, it is difficult to increase the aperture of the projection lens, and the illumination light reaches a sufficiently long distance. In addition, there is a problem that it is impossible to perform the process, and a problem that it is difficult to form a very fine pattern image.

In order to solve these problems, Japanese Patent Application Laid-Open No. 63-47710 proposes a method in which a plurality of illumination light sources of the above-described type for producing a large pattern image are used. However, such a configuration cannot solve the above-described problem of aberration correction of the projection lens.

In view of this point, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 2-101413 that a projection lens for projecting a pattern image is long in the longitudinal direction of the stripe of the pattern image.
A light projection system for focus detection using a plurality of lenses having a vertically short aperture shape has been proposed.

[0014]

As described above, even in the light projecting device, the projection range of the pattern image must be enlarged in accordance with the demand for enlargement of the focus detection area on the photographing device side. Further, no proposal has been made on a method of projecting a pattern image that is effective when the focus detection areas in two directions intersect at the center of the shooting screen.

Therefore, the present invention is suitable for both the intersection and the focus detection area other than the intersection, particularly when the photographing apparatus (or the observation apparatus) has a focus detection area intersecting in two directions. It is an object of the present invention to provide a light projecting device capable of projecting a pattern image.

[0016]

According to the present invention, there is provided a light projecting apparatus which projects a pattern image on a subject in order to detect a focus state of a photographing system or an observation system by a phase difference method. A first projection system for projecting a first pattern extending in a first direction onto a plurality of positions including a central focus detection area on a subject and arranged in the first direction;
And a second projection system for projecting the second pattern extending in the direction indicated by the arrow on a plurality of positions including the central focus detection area on the subject and arranged in the second direction.

This makes it possible to project a pattern image over a wide range of a subject while obtaining a good image formation state with a small number of light sources and a compact configuration. In particular, the focus detection areas are arranged so as to intersect in two directions. If
It is possible to realize a light projecting device capable of obtaining a good focus detection result in both the intersection and the focus detection area other than the intersection.

In this case, the first projection system uses a projection optical element having a plurality of projection optical axes in the first direction,
It is preferable to use a projection optical element having a plurality of projection optical axes in the second direction.

Also, a difference is provided between the brightness of the pattern image projected by one of the first and second projection systems and the brightness of the pattern image projected by the other projection system, so that a bright pattern is obtained. The contrast on the image side may be increased to further improve the focus detection accuracy.

Further, each of the first projection system and the second projection system includes a light source having the same characteristics, an identical pattern mask disposed in front of the light source for forming a pattern image, and a plurality of projection systems. A projection optical element having the same characteristic having an optical axis (that is, configured as the same projection unit), and the first projection system and the second projection system are mutually 90 degrees in the optical axis direction. They may be arranged in different phases. By using two identical projection units in this manner, cost reduction can be achieved.

[0021]

(First Embodiment) FIGS. 1 and 2
1 shows a configuration of a pattern image projection system in the light emitting device according to the first embodiment of the present invention. FIG. 1 is a cross-sectional view of the projection system viewed from the direction orthogonal to the optical axis, and FIG. 2 is a front view of the projection system viewed from the direction of the optical axis (front).

The light projecting device of the present embodiment is mounted on (or can be mounted on) a photographing device such as a camera or an observation device such as a telescope, and is used to detect the focus state of the photographing optical system or the observation optical system. used. Then, using the pattern image projected by the light projecting device, focus detection is performed by a focus detection device included in an imaging device or an observation device, and the result is
It is sent to the control circuit of the photographing device and the observation device, and is used for focus adjustment control of the photographing optical system and the observation optical system.

The projection system includes a first projection system A and a second projection system B, which are independent projection systems.

In FIG. 1, reference numeral 1-A denotes an LED as a light source of the first projection system A, and a linear pattern electrode (pattern mask) as a first pattern extending in the horizontal direction (first direction) on the front surface thereof. Having. 1-B is the second projection system B
And a linear pattern electrode (pattern mask) as a second pattern extending in the vertical direction (second direction) on the front surface of the LED.

2-A is a projection lens (projection optical element) of the first projection system A corresponding to the light source 1-A, and 2-B is a projection lens of the second projection system B corresponding to the light source 1-B. It is a lens (projection optical element).

The projection lens 2-A has an opening shape that is long in the horizontal direction and short in the vertical direction, and has four optical axes indicated by circles in FIG. LE
An image (pattern image) of the pattern electrode formed by the light from D1-A is projected on the object side in a form of four in a horizontal direction.

The projection lens 2-B has an opening shape that is long in the vertical direction and short in the horizontal direction, and has three optical axes indicated by circles in FIG. ,
An image (pattern image) of a pattern electrode formed by light from the LED 1-B is projected on the subject side in a form of three in a vertical direction.

FIG. 3 shows a pattern image projected on the object side by the projection system. Projection pattern image 4-A
Is formed as a series of pattern images in which four pattern images projected by the projection lens 2-A are arranged side by side in the horizontal direction. Also, the projected pattern image 4-B
Is formed as a series of pattern images in which three pattern images projected by the projection lens 2-B are arranged in the vertical direction.

FIG. 4 shows a focus detection area in a photographing device to which the light projecting device of this embodiment can be attached.
At the center of the screen, focus detection areas (central focus detection areas) 5-1 and 5-2 extending in the vertical and horizontal directions are formed in a shape crossing a cross. The focus detection area 5
-2 focus detection areas 5-3 on both sides in the horizontal direction
5-4, 5-5, and 5-6 are arranged, and the five focus detection areas 5-2 to 5-6 arranged in the horizontal direction have a shape extending long in the vertical direction.

Also, focus detection areas 5-7 and 5-8 are arranged one by one on both sides in the vertical direction from the focus detection area 5-1. These three focus detection areas 5-1 arranged in the vertical direction are provided. , 5-7, 5-8 have a shape extending long in the horizontal direction.

In the focus detecting device of the photographing apparatus shown in FIG. 4, the focus state of the photographing system or the observation system is detected by a phase difference detection method. The correlation calculation for detecting the focus state is performed in the longitudinal direction of each focus detection area. (A direction orthogonal to the longitudinal direction of the pattern image).

FIG. 5 shows the pattern image projected onto the subject by the projection system and the focus detection area shown in FIG. 4 in an overlapping manner. The pattern image 4-A overlaps the position corresponding to the focus detection areas 5-2 to 5-6 arranged in the horizontal direction in the subject, and the pattern image 4-B overlaps the focus detection area 5- in the subject in the vertical direction. 1,5-7,5
It overlaps with the position corresponding to -8.

Here, in the first and second projection systems A and B, LEDs 1-A and 1-B as light sources having the same characteristics are used. If the projection lenses have the same focal length, the brightness of the projected image is proportional to the projection area of the lens (that is, the smaller the Fno, the brighter). For this reason,
The luminous flux from the LED 1-A is converted into 4 light by the projection lens 2-A.
Projection divided into three so that the center lens area for projecting light to the central portion is relatively large compared to the brightness of the pattern image 4-A in which the four pattern images formed by division are formed as a series. The central portion of the pattern image 4-B in which three pattern images formed by dividing the light beam from the LED 1-B into three by the lens 2-B become brighter. For this reason, the focus detection areas 5-1 and 5 long in the horizontal direction are provided.
−7, 5-8 increase the contrast of the image signal received,
The focus detection accuracy is improved.

In the focus detection device having the focus detection areas 5-1 and 5-2 whose centers cross each other, the focus can be obtained even if the illuminance of the pattern images projected in the horizontal and vertical directions is not changed. Although detection is possible, if one pattern image is made brighter than the other pattern image as in the present embodiment, the contrast on the one pattern image side is increased, and the focus detection accuracy is generally improved.

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention.
2 illustrates a configuration of a pattern image projection system in the light projection device according to the embodiment. FIG. 7 is a cross-sectional view of the projection system viewed from a direction orthogonal to the optical axis.

The light projecting device of the present embodiment is mounted on (or can be mounted on) a photographing device such as a camera or an observation device such as a telescope to detect the focus state of the photographing optical system or the observation optical system. used. Then, using the pattern image projected by the light projecting device, focus detection is performed by a focus detection device included in an imaging device or an observation device, and the result is
It is sent to the control circuit of the photographing device or the observation device, and is used for focus adjustment control of the photographing system or the observation system.

The projection system comprises a first projection system A and a second projection system B, which are independent projection systems.

In the figure, reference numeral 11-A denotes an LED as a light source of the first projection system A, and has a linear pattern electrode (pattern mask) as a first pattern extending in the horizontal direction on the front surface thereof. Reference numeral 11-B denotes an LED as a light source of the second projection system B, and a straight pattern electrode (pattern mask) as a second pattern extending in the vertical direction on the front surface thereof.
Having.

The first light source 12-A corresponds to the first light source 11-A.
A projection lens of the projection system A, and 12-B is a light source 11-B
Are the projection lenses of the second projection system B. In addition,
Both the projection lenses 12-A and 12-B have only one optical axis, unlike the projection lens of the first embodiment.

13-A and 13-B are projection lenses 12-
A projection panel (projection optical element) having a prism unit for projecting a pattern image passing through A and 12-B in a plurality of directions. In addition, as shown in FIG.
-B has a prism component in a direction orthogonal to the projection panel 13-A.

FIG. 8 shows the projection panels 13-A and 13-B.
Shows the optical action of the prism section. Actually, the projection panel 13-A and the projection panel 13-B are shifted in phase by 90 degrees (the direction in which the prism portion extends) when viewed in the optical axis direction.

The prism portion of the projection panel 13-A has four deflection angles different in the horizontal direction and each has the same area.
This has the effect of dividing the image into four in the direction as a projection image of the same light quantity. Therefore, as in the first embodiment, the pattern image that has passed through the projection lens 12-A is projected on the subject side in a form in which four pattern images arranged in the horizontal direction are connected in series in the horizontal direction.

Further, the prism portion of the projection panel 13-B has three deflection angles different in the vertical direction and the same area, respectively, so that the light beam passing through the projection lens 12-B is the same in the three vertical directions. This has the effect of dividing the light quantity into three as a projected image. Therefore, as in the first embodiment, the pattern image having passed through the projection lens 12-B is projected onto the subject in a form in which three vertically aligned pattern images are connected in series in the vertical direction.

The pattern images projected from the projection panels 13-A and 13-B intersect at the center of the screen, as shown in FIGS. 3 and 5, and are projected by the projection panel 13-A. The image overlaps the position corresponding to the focus detection areas 5-2 to 5-6 arranged in the horizontal direction in the subject, and the pattern image projected by the projection panel 13-B is the focus detection area arranged in the subject in the vertical direction. 5
−2, 5-7, 5-8.

Here, also in this embodiment, in the first and second projection systems A and B, the LEDs 11-A, which are light sources, are used.
11-B have the same characteristics. For this reason, the luminous flux from the LED 11-B is formed by equally dividing the luminous flux from the LED 11-B into three parts, compared to the brightness of a series of pattern images formed by dividing the luminous flux from the LED 11-A into four equal parts. The brightness of the pattern image formed by combining the three pattern images becomes brighter. For this reason, the contrast of the image signal received by the focus detection areas 5-1, 5-7, and 5-8 which are long in the horizontal direction increases, and the focus detection accuracy improves. Further, in the present embodiment, the first projection system and the second
Each using a light source having the same characteristics, the same pattern mask disposed on the front surface of the light source to form a pattern image, and a projection optical element having the same characteristics having a plurality of projection optical axes. The first projection system and the second projection system are arranged as the same projection unit, and are arranged at phases different from each other by 90 degrees when viewed in the optical axis direction, thereby achieving cost reduction.

(Third Embodiment) FIG. 9 and FIG.
14 shows a configuration of a pattern image projection system in a light projection device according to a third embodiment of the present invention. 9 is a cross-sectional view of the projection system as viewed from the direction orthogonal to the optical axis, and FIG. 10 is a front view of only the light source and the projection lens in the projection system as viewed from the direction of the optical axis (front).

The light projecting device of the present embodiment is mounted on (or can be mounted on) a photographing device such as a camera or an observation device such as a telescope to detect the focus state of the photographing optical system or the observation optical system. used. Then, using the pattern image projected by the light projecting device, focus detection is performed by a focus detection device included in an imaging device or an observation device, and the result is
It is sent to the control circuit of the photographing device or the observation device, and is used for focus adjustment control of the photographing system or the observation system.

The projection system includes a first projection system A and a second projection system B, and are independent projection systems.

In the figure, 21-A is an LED as a light source of the first projection system A, and has a linear pattern electrode (pattern mask) as a first pattern extending in the horizontal direction on the front surface thereof. Reference numeral 21-B denotes an LED as a light source of the second projection system B, and a linear pattern electrode (pattern mask) as a second pattern extending in the vertical direction on the front surface thereof.
Having.

The first light source 22-A corresponds to the first light source 21-A.
A projection lens of the projection system A, wherein 22-B is a light source 21-B
Are the projection lenses of the second projection system B. In addition,
These projection lenses 22-A and 22-B are the same as the projection lens 2-A of the first embodiment, and have a structure having four optical axes indicated by marks in FIG.

In this embodiment, the LEDs 21-A, 21-
B (including the linear pattern electrode) and the projection lens 22-
A and 22-B having the same characteristics are used, and the LEDs and the projection lenses of the first projection system A and the second projection system B are arranged with a phase shift of 90 degrees when viewed in the optical axis direction. By using the unit including the LED and the projection lens having the same configuration for the first projection system A and the second projection system B, the cost of the focus detection device can be reduced.

Reference numeral 23 denotes a combined projection panel (combined optical element) having a prism unit for combining the four pattern images formed by the projection lens 22-B into three.

Here, FIG. 11 shows a composite projection panel 23.
2 shows a front view and a cross-sectional view of FIG. Composite projection panel 2
The portion indicated by 23-A in 3 is a surface without a prism portion. Also, 23-B of the composite projection panel 23
The portion indicated by is the lower view of FIG. 11 (a cross-sectional view taken along line CC in the upper figure).
As shown in FIG. 7, the prism section has two different deflection angles.

The prism section 23-B is provided with the projection lens 2
-B, the three pattern images formed in the vertical direction
It has an optical action of superimposing again so as to have the same pattern image length.

As in the first embodiment, the pattern images having passed through the prism-free portion 23-A of the projection lens 22-A and the combined projection panel 23 are formed by a series of four pattern images arranged in the horizontal direction. Is projected on the subject side in a form connected to.

The pattern images of the projection lens 22-B and the combined projection panel 23 which have passed through the prism portion 23-B are connected to the subject side in a continuous form having a pattern image length of three. Projected.

The pattern images projected on the subject side intersect at the center of the screen as shown in FIGS. 3 and 5, and the pattern images projected by the projection panel 23-A are arranged in the horizontal direction on the subject. Focus detection area 5-
The projection panel 13-
The pattern image projected by B overlaps with the position corresponding to the focus detection areas 5-1, 5-7, and 5-8 arranged in the vertical direction on the subject.

Here, also in this embodiment, in the first and second projection systems A and B, the LEDs 21-A, which are light sources, are used.
21-B having the same characteristics is used. For this reason, compared with the brightness of the pattern image in which the four pattern images formed by dividing the light beam from the LED 21-A into four, the light beam from the LED 21-B is divided into four, The brightness of the central part of the pattern image formed as three pattern images formed by combining three in an overlapping manner becomes brighter. For this reason, the contrast of the image signal received by the focus detection areas 5-1, 5-7, and 5-8 which are long in the horizontal direction increases, and the focus detection accuracy improves.

FIG. 15 shows a configuration of a main part of a photographing apparatus equipped with a light emitting device to which the present invention is applied. In the figure, M
1 is an optical axis of the taking lens 5. Reference numeral 8 denotes a focus detection optical system provided in the photographing apparatus. The focus detection optical system passes through a quick return mirror 6 for guiding a light beam to a finder optical system (not shown) in the figure and passes through a reflection mirror 7 for a focus detection light beam. It is led to 8.

Reference numeral 9 denotes an image forming position of the photographing lens 5, on which an image recording device such as a film or a CCD is arranged. At the time of image recording, the quick return mirror 6 and the reflection mirror 7 are retracted out of the optical path to guide the light beam from the photographing lens 5 to the image forming position 9.

M2 is the optical axis of the auxiliary light projecting device according to the present invention. The patterned image of the light source 1-A is projected on the subject side by the light projecting lens 2-A. At the time of focus detection, the pattern image projected on the subject is guided to the focus detection device 8 via the photographing lens 5, and focus detection is performed.

[0062]

As described above, according to the present invention,
With a small number of light sources and a compact configuration, it is possible to project a pattern image onto a wide range of a subject while obtaining a good image-forming state. Especially when the focus detection areas are arranged in two directions, It is possible to realize a light projecting device capable of obtaining a good focus detection result in any of the focus detection areas other than the section and the intersection.

[Brief description of the drawings]

FIG. 1 is a sectional view of a projection system in a light projection device according to a first embodiment of the invention.

FIG. 2 is a front view of the projection system.

FIG. 3 is an explanatory diagram of a pattern image projected by the projection system.

FIG. 4 is a layout diagram showing a focus detection area of the photographing apparatus.

FIG. 5 is a layout diagram showing a pattern image projected by the projection system and a focus detection area of a focus detection device.

FIG. 6 is a sectional view of a projection system in a light projection device according to a second embodiment of the invention.

FIG. 7 is a sectional view of a projection panel according to the second embodiment.

FIG. 8 is an explanatory diagram of an optical function of a projection panel according to the second embodiment.

FIG. 9 is a sectional view of a projection system in a light emitting device according to a third embodiment of the invention.

FIG. 10 is a front view of a projection system according to the third embodiment.

FIGS. 11A and 11B are a front view and a cross-sectional view taken along line CC of the composite projection panel according to the third embodiment.

FIG. 12 is a sectional view of a projection system in a conventional light projecting device.

FIG. 13 is a front view of a projection pattern in the conventional projection system.

FIG. 14 is an explanatory diagram of a pattern image and a projection range projected by the conventional projection system.

FIG. 15 is a cross-sectional view of a main part of a photographing apparatus equipped with a light projecting device according to an embodiment of the present invention.

[Explanation of symbols]

A first projection system B second projection system 1-A, 1-B, 11-A, 11-B, 21-A, 21
-B Light source (LED) 2-A, 2-B, 12-A, 12-B, 22-A, 22
-B Projection lens 13-A, 13-B Projection panel 4-A, 4-B Pattern image 5-1-5-8 Focus detection area 23 Synthetic projection panel

Claims (10)

[Claims] 1. A light projecting device for projecting a pattern image on a subject in order to detect a focus state of a photographing system or an observation system by a phase difference method, wherein a first pattern extending in a first direction is projected on the subject. A first projection system that projects a plurality of positions aligned in the first direction that includes a central focus detection area, and a second pattern that extends in a second direction includes a central focus detection area on a subject. A second projection system that projects onto a plurality of positions arranged in a second direction. 2. The method according to claim 1, wherein a difference is provided between the brightness of the pattern image projected by one of the first and second projection systems and the brightness of the pattern image projected by the other projection system. The light emitting device according to claim 1, wherein: 3. The light source of the first projection system and the light source of the second projection system have the same characteristic, and are projected by one of the first and second projection systems. Since the number of pattern images projected by the other projection system is smaller than the number of pattern images projected by the other projection system, the brightness of the pattern image projected by the one projection system is reduced. The light projecting device according to claim 2, wherein the light emitting device is brighter than the brightness of the light emitting device. 4. The first projection system includes a projection optical element having a plurality of projection optical axes in the first direction, and the second projection system includes a plurality of projection lights in the second direction. 4. The light projecting device according to claim 1, further comprising a projection optical element having an axis. 5. The light projection device according to claim 4, wherein the projection optical elements of the first and second projection systems are lenses. 6. The light projection device according to claim 4, wherein the projection optical elements of the first and second projection systems are prisms. 7. A light source, wherein the first projection system and the second projection system have the same characteristics, an identical pattern mask arranged on the front surface of the light source to form each pattern, and And the first projection system and the second projection system are arranged at phases different from each other by 90 degrees when viewed in the optical axis direction. The light projecting device according to any one of claims 1 to 6, wherein 8. The number of pattern images projected by one of the first and second projection systems is a predetermined number smaller than the number of pattern images projected by the other projection system, The said other projection system has a combining optical element for combining and projecting a plurality of pattern images formed by the projection optical elements of the other optical system into the predetermined number of pattern images. The light emitting device according to any one of 1 to 6. 9. A light projecting device according to claim 1, wherein said light projecting device can be mounted on said photographing optical system based on a focus state detection result using a pattern image projected by said light projecting device. An imaging device for performing a focus adjustment operation. 10. A light projecting device according to claim 1, wherein said light projecting device is mounted on said observation optical system based on a focus state detection result using a pattern image projected by said light projecting device. An observation device, which performs a focus adjustment operation.