JPH0611646A - Automatic focusing light device - Google Patents

Abstract

PURPOSE:To solve the problem of too narrow focusing area which occurs when a pattern is projected on an object with a simple constitution. CONSTITUTION:This automatic focusing light device is provided with a pattern member with the specified pattern image 108 and a projecting optical system projecting the pattern 108 on the object, and attached or incorporated into a TTL camera 105 provided with a focal detection device including a photoelectric conversion element array 106. The pattern image 108 is projected toward the object in a state where the object light quantity is insufficient and the projection pattern image 108 on the object is detected at the focal detection device of the camera 105 and the pattern member is disposed to be inclined against a surface orthogonal to an optical axis of a projecting optical system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocusing light device used with an automatic focus detection device of a TTL camera.

[0002]

2. Description of the Related Art A photoelectric conversion element array of an automatic focus detection device for a TTL camera is usually arranged one-dimensionally in the longitudinal direction of the film at a position optically equivalent to the center of the film (near the optical axis of the lens). In order to guide the subject light onto the element array, the subject light transmitted through the lens is guided through the semi-transmissive portion of the main mirror and the sub-mirror, or the reflecting mirror.

There is no problem in the focus detection of the automatic focus detection device of the camera when the brightness of the subject is sufficiently bright, but when it is dark, the focus detection time becomes extremely long or the focus cannot be detected. May be. In order to avoid such a situation, when the subject becomes darker than a certain brightness, the distance from the optical axis of the shooting lens of the camera, for example,
As shown in FIG. 5, a projection pattern 108 for focus detection is projected from a dedicated light emitting unit 110 provided in a strobe device mounted on a camera onto a subject through a projection lens by a projection light source 109 (for example, an LED element). The focus detection is performed by detecting the reflected light of the projection pattern 108 by the automatic focus detection device.

[0004]

However, even when a projection pattern is projected onto a subject using a conventional device, the pattern projection image is formed on the subject in a very narrow range, and on a subject outside the range, Accurate focus detection cannot be performed because the projected pattern image is blurred. Therefore, it is an object of the present invention to widen the image formation range of a pattern projection image with a simple configuration.

[0005]

SUMMARY OF THE INVENTION The present invention provides a focus detection device including a pattern member having a predetermined pattern image and a projection optical system for projecting the pattern image on a subject, and including a photoelectric conversion element array. It is attached to or built in the TTL camera provided, and when the light amount of the subject is insufficient, the pattern image is projected toward the subject, and the pattern image projected on the subject is detected by the focus detection device of the camera. In the automatic focusing light device, the pattern member is arranged to be inclined with respect to a plane orthogonal to the optical axis of the projection optical system.

[0006]

According to the present invention, the image forming range of the pattern image on the object can be widened with a simple structure.

[0007]

1 to 4 show an embodiment of the present invention. Figure 1
FIG. 3 is an explanatory diagram showing the relationship between the optical axis of the photographing lens of the camera and the projection pattern from the autofocusing light device. In FIG. 1, the single-lens reflex camera 105 is
Photoelectric conversion element array 10 for automatic focus detection on the bottom of the body
6 and the subject image incident from the photographing lens 104 capable of automatic focusing operation is passed through the reflecting mirror to the element array 106.
The focus detection process is performed by the automatic focus detection device. At this time, if the subject is darker than a predetermined brightness and the focus detection processing of the automatic focus detection device does not operate normally, focus detection is performed from the autofocusing light device built in the strobe device (not shown) attached to the camera 105. The projection pattern 108 for projection is projected on the subject through the projection lens 107. At that time, whether or not the subject has a predetermined brightness is automatically detected by using the photoelectric conversion element array 106 of the automatic focus detection device, and the autofocusing light device is automatically operated. Alternatively, the fact that the subject is dark may be displayed on a finder or the like, and the user may manually operate it. The projection pattern 108 is composed of light emitting diodes (hereinafter referred to as LEDs), and when the projection pattern is projected on the element array 106, the projection pattern is an image extending in a direction perpendicular to the arrangement direction of the element array 106. Projected as. In FIG. 1, the projection pattern 108 (X-
Y) is projected, it is shown that the projection pattern incident on the element array 106 changes depending on the distance of the subject due to the relationship between the projection pattern 108 and the optical axis 1 of the taking lens 104, that is, at the long distance L1, The intersection Z1 of the projection pattern 108 (X1-Y1) is mainly incident on the element array 106. Similarly, when the distance is L2, the intersection Z2 of the projection pattern 108 (X2-Y2) is mainly the element array 106. Similarly, it can be seen that the portion of the intersection Z3 of the projection pattern 108 (X3-Y3) is mainly incident on the element array 106 at the short distance L3. The automatic focus detection device in the camera can detect the projection pattern 108 to detect the focus even on a dark subject.

Next, the structure of this autofocusing light device will be described. FIG. 2 shows a projection lens 107 and a projection pattern 1 in the autofocusing light device.
08 is an explanatory view for explaining the relationship with FIG.
08 is an explanatory view for explaining the structure of FIG.
8 is a circuit diagram of a circuit for driving and controlling 8 of FIG. The autofocusing light device is composed of a projection lens 107 and a projection pattern 108. As shown in FIG. 3, the LEDs forming the projection pattern 108 are formed by arranging a plurality of LED chips 201 to 203 in a line. There is. In this way, the automatic focusing light device has a plurality of LEs.
The D chips 201 to 203 are arranged to form the element array 106.
Above, a long projection pattern is formed in one direction perpendicular to the arrangement direction. Instead of a plurality of LED chips 201 to 203 arranged in one direction as described above, L
If one that is long in one direction is made without dividing the ED, it is not practical because it is difficult to manufacture, and the yield and the cost are increased. for that reason,
As LEDs forming the projection pattern 108, a plurality of L
The ED chips 201 to 203 are arranged and used.

As shown in FIG. 2, in the autofocusing light device, the projection lens 1 is placed in front of the projection pattern 108.
07 are arranged. The optical axis of the projection lens 107 is tilted by a predetermined angle with respect to the optical axis of the photographing lens 104, and the projection pattern 108 is an angle θ from a plane m perpendicular to the optical axis 11 of the projection lens 107. It is installed on an inclined surface. In this way, the projection pattern 108
Since the optical path from the taking lens 107 to the LED chip 201 (X side) of the projection pattern 108 is closer to the LED chip 203 (Y side), the LED chip 201 Projected image (X
1 to X3 side), the projected image of the LED chip 203 (Y
(1 to Y3 side) forms an image at a position far from the taking lens 104. Therefore, since the projection pattern 108 also forms an image on the subject while tilting the projection pattern by a certain angle, the projection pattern forms an image without blurring within a certain range on the optical axis l. Therefore, for example, Optical axis l
Than a projection pattern in which an image is formed only on a surface perpendicular to (in this projection pattern, an image is formed only on the vertical surface of the optical axis 1 on the subject without blurring, but on a surface inclined from the vertical surface, it is blurred)
The range in which an image is formed on the subject without blurring of the projection pattern is widened, and the focus detection function is effectively performed.

Assuming that the projection pattern 108 is projected on the subject in this autofocusing light device, the projected images of the plurality of LED chips 201, 202, 203 are projected on the subject as they are in one direction as shown in FIG. Will be done. The LED chip has an electrode made of a metal film in the center thereof, so that the central electrode portion is dark and the periphery of the electrode is bright. Then, the projected image of the LED chip has a bright portion 201a, as shown in FIG.
The dark portion 201b (same for other projected images) is projected on the subject, that is, a direction orthogonal to the arrangement direction (left and right direction in the drawing) on the element array 106 via the photographing lens 104 (in the drawing). LED chips 201, 2 in the vertical direction)
The projected images of 02 and 203 are projected. The automatic focus detection device of the camera uses the projection pattern 108 with this change in brightness.
By detecting the (projected image of the LED chips 201, 202, 203), a known automatic focusing operation is performed.

As shown in FIG. 1, the projection pattern 108 has an optical axis l of the photographing lens 104 depending on the object distance.
The LED chip 201 of the projection pattern 108 intersects at a long distance L1, the LED chip 202 of the projection pattern 108 intersects at a medium distance L2, and the LE of the projection pattern 108 at a short distance L3.
It intersects with the D chip 203. Then, in general, when the brightness of the projection pattern 108 is uniform, even if a projection pattern with sufficient illuminance is obtained at a medium distance, a projection pattern with sufficient illuminance is obtained at a short distance, resulting in a reduction in current consumption. This is wasteful, and a projection pattern with insufficient illuminance can be obtained at a long distance, which is inappropriate for focus detection.
Therefore, if the current is supplied to the LED chip of the projection pattern 108 in consideration of the intersection of the projection pattern 108 and the optical axis 1 of the photographing lens 104 and the illuminance of the projection pattern on the subject, it is useless. Optimal drive control that does not have to be possible. The drive control circuit for the projection pattern 108 will be described below.

As can be seen from FIG. 1, the projection pattern 10
The LED chip 201 of No. 8 has a photoelectric conversion element array 106 for focus detection when a subject is located at a long distance L1.
In addition, the LED chip 203 is incident on the photoelectric conversion element array 106 for focus detection when the subject is located at the short distance L3. Therefore, in order for the automatic focus detection device to perform focus detection, the illuminance of the projection pattern on the subject must be sufficient even at the long distance L1.
It can be seen that the LED chip 201 corresponding to 1 requires a large current, and the LED chip 203 corresponding to the short distance L3 can obtain sufficient illuminance even with a small current.

In FIG. 4, the circuit for driving and controlling the projection pattern 108 is configured to flow currents having different current values to the LED chips 201 to 203.
LED chips 201-203 and transistors Tr1-
Tr3 and the resistors R1 to R3 form series circuits connected in series, and these series circuits are connected in parallel between the power supply Vcc and the ground GND. The bases of these transistors Tr1 to Tr3 are connected to the output terminal of the OP amplifier 31. A reference potential E3 for setting a constant current is connected to a non-inverting input terminal of the OP amplifier 31. The resistance values of the resistors R1 to R3 are: resistance R3> resistance R
2> resistor R1 in that order, and therefore LED chip 2
The current gradient supplied to 01 to 203 is based on the LED chip 2
01 has the largest current value, then LED chip 2
The current value is larger in the order of 02, 203. Therefore, in the projection pattern 108, the brightness of the LED chip 201 is the highest, and then the brightness of the LED chips 202 and 203 is higher in that order.

Therefore, by utilizing the structure of the LED chip, it is possible to easily obtain an appropriate luminance distribution of the projection pattern which assists the automatic focusing operation depending on the object distance.
That is, by arranging a plurality of LED chips vertically
By a simple current control method in which a current value matched to each LED chip corresponding to the subject distance is supplied by a chip drive control circuit, automatic focus detection can be appropriately performed on a dark subject of any subject distance. .
Further, as shown in FIG. 2, since the projection pattern 108 is tilted with respect to the optical axis of the projection lens 107, there is the same effect as if the depth of field is increased, and the projection pattern projected onto the subject is the subject. The number of sharply imaged portions above increases, which works effectively for focus detection. Furthermore,
Since the shapes of a plurality of LED chips are projected as they are, the structure is simple, and the autofocusing light device is advantageous in terms of cost.

[0015]

As described above, according to the present invention, a pattern image is formed on a subject with a simple structure by arranging the pattern member so as to be inclined with respect to the plane orthogonal to the optical axis of the projection optical system. The range to be used becomes wider, and focus detection is performed properly.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a relationship between an optical axis of a photographing lens of a camera and a projection pattern from an autofocusing light device.

FIG. 2 is an explanatory diagram illustrating a relationship between a projection lens 107 and a projection pattern 108 in the autofocusing light device.

FIG. 3 is an explanatory diagram illustrating a configuration of a projection pattern 108.

FIG. 4 is a circuit diagram of a circuit for driving and controlling a projection pattern 108.

FIG. 5 is an explanatory diagram of an autofocusing device that forms a projection pattern by irradiating a projection plate having the projection pattern with a light source.

[Explanation of symbols]

 106 ... Photoelectric conversion element array 107 ... Projection lens 108 ... Projection pattern 201-203 ... LED chip

Claims (2)

[Claims] 1. A TTL provided with a focus detection device including a pattern member having a predetermined pattern image and a projection optical system for projecting the pattern image on a subject, and a focus detection device including a photoelectric conversion element array.
Attached to the camera or built-in, project the pattern image toward the subject when the subject light quantity is insufficient,
An auto-focusing light device for detecting the pattern image projected on a subject by a focus detection device of the camera, wherein the pattern member is arranged tilted with respect to a plane orthogonal to an optical axis of the projection optical system. An auto focusing light device characterized by: 2. The autofocusing light device according to claim 1, wherein the pattern member is a light emitting element having a predetermined shape.