JP2001141984A - Automatic focusing device for electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize automatic focusing at high speed with high precision by adopting a simple constitution to solve the problem that it takes time for focusing and precision cannot be secured in the case of a low luminance or a low contrast in the contrast system. SOLUTION: An automatic focusing device for electronic camera is provided with a photographic leans 11 which forms a subject image, a CCD imaging device 13 which converts the subject image formed by the photographic lens 11 to a picture signal, an active trigonometrical distance measurement mechanism 30 which throws light to a subject to measure an objective subject distance, and a focusing mechanism 20 in the contrast system which uses a high frequency component of an output signal in the center area of the imaging device 13 to perform focusing, and the photographic lens 11 is driven on the basis of the focusing means in the contrast system to perform focusing after being driven to a position a certain extent short of an in-focus position measured by the mechanism 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing device, and more particularly, to an automatic focusing device for an electronic camera having an image sensor.

[0002]

2. Description of the Related Art Conventionally, as an automatic focusing device of an electronic camera, an image pickup device (hereinafter referred to as "CCD" as a representative of the image pickup device) on which a subject image incident through a photographic lens is formed
The image data of an area of a predetermined portion on the upper portion is read out for each predetermined driving unit of the lens, and the lens is driven to a position where the contrast is maximized, which is a so-called hill-climbing method (one of the contrast methods). Has been adopted.

[0003] However, this method has several problems as follows.

At low luminance, the focusing time becomes extremely long. Due to the principle of the hill-climbing method, the position of the subject can only be specified after scanning the entire lens drive range. In addition, one CCD integration time is required per predetermined drive unit of the lens, and at low brightness where the CCD integration time is longer than 1/15 second, the focusing time becomes extremely long as the focusing time exceeds 1 second. There was a problem. Further, since the CCD sensitivity generally decreases as the number of pixels increases, in an electronic camera pursuing photographic image quality, the CCD integration time is becoming longer, and the above-described problem becomes conspicuous.

[0005] When the contrast is low, there is a problem that the peak of the contrast cannot be captured and focusing becomes impossible, and the operational feeling of the camera is significantly impaired.

Since the electronic camera has a smaller imaging surface area than the silver halide camera, the focal length of the taking lens is short, so that the depth of field is extremely deep. However, there is a problem that the effective subject distance cannot be detected. This problem becomes more conspicuous as the focal length of the taking lens becomes wider.

In order to solve the above-mentioned problem of the focusing time, an AF sensor is arranged near a planned focal plane on which a subject image is formed and at positions before and after the focal plane. A method of detecting a direction and driving a lens is disclosed in Japanese Patent Application Laid-Open No. 55-155308. However, this is only for the AF sensor
This is a technology in a silver halide camera that can tune the electrical characteristics and optical layout of D.
It is not applicable to an electronic camera that also serves as a CCD as a sensor.

Japanese Patent Application Laid-Open No. Hei 7-43605 discloses a method in which an AF method having different types of a contrast method and a phase difference method is used together, coarse adjustment is performed by a phase difference method, fine adjustment is performed by a contrast method, and a focusing operation is performed. The method is open to the public. However, the autofocus device described in the publication is based on a silver halide camera, and it is necessary to specially provide an area sensor for a contrast system in addition to a phase difference AF device. The size increases and the cost increases. Also, the low contrast problem of both types combined here cannot be solved.

Further, in order to solve the problem of focusing time at low luminance and the problem of low contrast, an active system in which auxiliary light is projected to compensate for a weak point of the passive system is known. When there is a distant place or when the surroundings are bright and the contrast is low, a sufficient amount of light cannot be obtained, and there is no effect unless the target is relatively close.

If the intensity of the auxiliary light is increased in order to enhance the effect of the active system, the power consumption for projecting light becomes enormous, which is a problem for an electronic camera which needs to reduce the power consumption. (Originally, in the hill-climbing method, the auxiliary light projection must be continued during the lens driving time in principle, and its power consumption is not negligible in the electronic camera unlike the silver halide camera.) Also, the spectrum of the auxiliary light Must be placed in the visible region for the dual purpose of the image sensor, and unnecessarily increasing the power of the light may cause pain such as dazzling to the subject, which is not desirable.

As described in Japanese Patent Application Laid-Open No. 9-325262, as one of the methods for solving the above-mentioned problem, combinations for the purpose of compensating for weaknesses of two different methods, an active method and a passive method, are used. There is a method in which the specific conditions of the above method are specified and used selectively. However, electronic cameras are different from silver halide cameras,
There are the following restrictions (1) to (4) specific to an electronic camera, namely, a focusing device that also serves as an image sensor.

(1) Due to the problem of image quality, the sensitivity of the image sensor cannot be simply increased. (2) Due to the problem of image resolution, the pixel size cannot be set optimally for AF. (3) The spectral region cannot be optimized due to the RGB filter and the infrared cut filter. (4) Since full-screen reading is required, the image sensor reading speed cannot be optimally designed for AF.

For this reason, it is difficult to optimize the image pickup device including the layout optically and electrically as a passive type distance measuring device or focusing device like a silver halide camera, as in the prior art. Significant improvement of the focusing device cannot be expected only by the selective use.

On the other hand, in the method in which coarse adjustment is performed by the active triangulation method and fine adjustment is performed by the contrast method, when light is projected to an object halfway in the active triangulation method, extreme short distance data or long distance There is a problem that data is output, which causes a problem that a contrast peak does not exist within a predetermined range of a lens driving range based on the active triangulation ranging output.

[0015] Furthermore, the so-called parallax occurs in which the light projection position by the active triangulation and the position of the focus detection area of the CCD by the contrast method vary depending on the subject distance, and a situation occurs in which a contrast peak cannot be detected. There was a problem.

In addition, when an infrared beam is projected on the subject to the left at one end, and when the infrared beam is projected at the right end to the subject (which occurs when light is projected near the boundary of a subject that coexists in perspective, In the so-called spot chipping problem), a subject distance which is completely shifted in the opposite direction is output. Therefore, after the focusing is performed by the active triangulation method, after the photographing lens is driven in a predetermined range based on the contrast method, the contrast is reduced. There is a problem that the peak position cannot be specified and the focusing time becomes longer.

As a countermeasure in such a case, the width of the above-mentioned predetermined range may be increased with a margin in order to reliably capture the peak of the contrast. However, increasing the width of the predetermined range shortens the original focusing time. Contradict the purpose of doing so.

[0018]

As described above, if a contrast method is conventionally employed in an automatic focus adjusting device of an electronic camera, it takes a long time to adjust the focus and a problem that the accuracy cannot be ensured under low brightness or low contrast. Invited.

The present invention has been made in consideration of the above circumstances, and has as its object to simply solve the problem that it takes time to adjust the focus in the contrast method and the accuracy cannot be ensured under low luminance or low contrast. It is an object of the present invention to provide a high-speed and high-accuracy automatic focusing apparatus for an electronic camera.

[0020]

(Structure) In order to solve the above problem, the present invention employs the following structure.

That is, according to the present invention, in an automatic focusing device for an electronic camera, a photographing lens for forming a subject image and an image pickup device for converting the subject image formed by the photographing lens into an image signal. Active triangulation means for projecting light to the object and measuring the object distance of the object,
A focus adjusting means for adjusting the focus using a high-frequency component of an output signal in a predetermined area of the image sensor, and a predetermined amount with respect to a focusing position measured by the active triangulation means; After the lens is driven to the front focus position or the rear focus position, a photographing lens drive control unit that drives the photographing lens based on the focus adjusting unit based on the contrast method to perform focus adjustment is provided.

According to another aspect of the present invention, there is provided an automatic focusing device for an electronic camera, comprising: a photographing lens for forming a subject image; and an image pickup device for converting the subject image formed by the photographing lens into an image signal. Subject brightness detecting means for detecting the brightness of the subject, active triangulation means for projecting light to the subject to measure the subject distance, and focusing using a high frequency component of an output signal in a predetermined area of the image sensor. When the brightness of the subject is determined to be higher than or equal to a predetermined value by the subject brightness detecting means and the focus adjusting means based on the contrast method for performing the adjustment, the taking lens is adjusted based on the distance measurement output of the active triangulation means. Is driven to the position of the front focus or the rear focus by a predetermined amount with respect to the in-focus position, and then the photographing level is adjusted based on the focus adjusting means based on the contrast method. It performs a focus adjustment by driving a's,
When it is determined that the subject brightness is low brightness equal to or less than a predetermined value, a photographing lens drive control unit that drives the photographing lens to a focus position based on the distance measurement output of the active triangulation unit to perform focus adjustment; It is characterized by having.

Here, preferred embodiments of the present invention include the following.

(1) The object luminance detecting means detects the luminance of the object based on the output signal of the image sensor.

(2) The amount of the front focus or the rear focus is an amount that depends on the focal length or the aperture value of the photographing lens at the time of photographing.

(3) The active triangulation means projects an infrared beam onto the subject a plurality of times in one ranging operation, and measures the subject distance based on a composite signal obtained as a result of the projections a plurality of times. Things.

(4) The taking lens drive control means sets the taking lens to the first position based on the distance measurement output of the active triangulation means.
After driving at the second driving speed, the photographing lens is driven at a second speed lower than the first speed based on the focus adjusting means based on the contrast method.

(5) The active triangulation means measures the subject distance based on output signals of two light receiving elements arranged on both sides of the light projection unit.

(6) The active triangular distance measuring means includes: a short distance light projecting means for projecting light to a subject corresponding to an image in a predetermined area of the image sensor when the subject is at a short distance; And a long-distance light projecting unit for projecting light to a subject corresponding to an image in a predetermined area of the image sensor when the image capturing device is located at

(Operation) According to the present invention, since the contrast method and the active triangulation method are used together, the focus can be adjusted at high speed and with high accuracy. Since the sensor used for the contrast method also serves as the image sensor of the electronic camera, the configuration is simplified.

Also, after driving to the position of the front focus or the rear focus (the second position) by a predetermined amount with respect to this focus position instead of the focus position (first position) by the active triangulation means, Since the focus adjustment is performed by driving the photographing lens based on the focus adjusting means using the contrast method, the focusing operation using the contrast method can be performed quickly, and the focus adjustment can be performed at a higher speed.

When it is determined that the brightness of the object is low or lower than a predetermined value, the photographing lens is driven to a focusing position (first position) based on the distance measurement output of the active triangulation means to adjust the focus. To prevent the accuracy of the automatic focus adjustment by the contrast method under low brightness from decreasing,
High-speed and high-precision automatic focusing can be performed.

Further, the amount of the front focus or the rear focus for setting the taking lens before the focusing operation by the contrast method is
By setting variably according to the focal length or aperture value of the photographing lens at the time of photographing, the amount of blur at the start of the focusing operation by the contrast method can be always the same, and unnecessary movement can be reduced to achieve hill climbing AF. Can be performed more quickly.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a diagram illustrating a main configuration of an electronic camera according to the embodiment.

In the figure, reference numeral 11 denotes a photographing lens, which comprises a focusing lens 11a, a zoom lens 11b, a lens 11c, and the like. Reference numeral 12 denotes an aperture, 13 denotes a solid-state image sensor (hereinafter abbreviated as CCD), such as a CCD, 14 denotes lens driving means for driving a focusing lens 11a, and 15 denotes zoom driving means for driving a zoom lens 11b. ,
Reference numeral 16 denotes aperture control means, reference numeral 20 denotes a digital process circuit for performing various image processing from an output signal (image signal) of the CCD 13, reference numeral 30 denotes distance measuring means for measuring a distance to a subject by an active triangulation method, and reference numeral 41 Is a system controller for controlling each part, 42 is a strobe light emitting means for emitting strobe light, 43 is a flashmatic control means for controlling strobe light emission, and 44 is a liquid crystal for displaying a photographed image and other information. Display (L
CD) and 45 indicate memory cards for storing image data.

FIG. 2 is a diagram for explaining the specific configuration of the focus adjusting mechanism and the operating principle thereof according to the present embodiment. The distance measuring means 30 includes an infrared LED 31, a position detecting element (PSD) 32, a light projecting lens 34, a light receiving lens 35, and an active triangulation control circuit 38. The distance measuring means 30 irradiates the subject 50 with the light emitted from the infrared LED 31 through the light projecting lens 34 to form a projected spot image 51 on the subject 50. The projected light spot image 51 is guided to the PSD 42 through the light receiving lens 35, and a light receiving spot image 52 is formed on the PSD 32.
The position of the light receiving spot image 52 is detected by D32. The active triangulation control circuit 38 measures the distance to the subject 50 based on the detection signal of the PSD 32.

Here, in order to further improve the measurement accuracy, an infrared beam is projected onto the subject 50 a plurality of times by one distance measuring operation.
The subject distance may be measured based on a composite signal obtained as a result of a plurality of projections. By performing the projection a plurality of times, the total signal amount increases and the noise is canceled, so that the S / N can be improved.

The distance measuring signal from the distance measuring means 30 is supplied to a system controller 41, and the lens driving means 14 is controlled based on the distance measuring signal by an instruction from the system controller 41. Then, this lens driving means 14
Thereby, the focusing lens 11a is moved to a position corresponding to the distance measurement signal. Reference numeral 53 in the figure denotes a focus position by active triangulation.

The imaging output of the CCD 13 is supplied to a digital process circuit 20. This digital process circuit 2
At 0, various image processing is performed on the image pickup output, and a focusing operation by the contrast method is performed. That is, while moving the lens position within a predetermined range, the RF component of the imaging output at each position is detected, and the lens driving means 1 is set so that the RF component becomes the maximum (contrast peak).
4, the focus lens 11a is moved. In the figure, reference numeral 54 denotes a focus position by the hill-climbing method, 55 denotes a ∞ subject focus position, 56 denotes a contrast curve, and 57 denotes a contrast peak.

The image pickup output of the CCD 13 is supplied to a contrast detecting means 21 and a luminance detecting means 22. Then, the processing process is changed according to the detected contrast and luminance.

Next, the focus adjustment operation and the strobe control operation in this embodiment will be described.

FIG. 3 is a flowchart showing the focus adjustment operation in this embodiment. First, when the camera is released, active triangulation is performed by the distance measuring means 30 shown in FIG. 2 (S1). Then, the focusing lens 11a is driven by the lens driving unit 14 based on the distance measurement data, and the lens 11a is set to a focus position (first position) 53 by active triangulation (S).
2).

Next, the luminance of the subject is detected by the luminance detecting means 22 based on the image pickup output of the CCD 13, and it is determined whether the detected luminance of the subject is higher (high luminance) or lower (low luminance) than a predetermined luminance ( S3). If it is determined that the brightness is high, the first position 5 indicated by the active triangulation is used.
The hill-climbing AF by the contrast method is performed within a predetermined range centered on 3 (S4). Specifically, the focus lens 11a is sequentially moved to a total of six points before and after the first position 53, and the contrast is detected from the imaging output at each point, and the lens 11a is moved to a position where the contrast reaches a peak. . Thereby, as shown in FIG. 2, the lens 11a is positioned and set at a position 54 where the contrast curve 57 becomes the contrast peak 57. Here, the predetermined range in the hill-climbing AF may be set to a range several times the allowable defocus amount of the photographing lens 11.

Next, the contrast of the subject is detected by the contrast detecting means 21 based on the image pickup output of the CCD 13, and it is determined whether the detected contrast is higher (OK) or lower (NG) than a predetermined value (OK). S5). If it is determined to be OK, the process proceeds to a shooting operation (S6).

If it is determined that the luminance is low in the luminance determination in S3, or if it is determined to be NG in the contrast determination in S5, the in-focus position (the first position) is determined based on the active triangulation data as in S2. The lens 11a is driven to position (53). After that, the procedure moves to the photographing operation of S6. That is, when focusing by the contrast method is not successful, the focus adjustment is performed only by the active triangulation method.

On the other hand, in the present embodiment, flashmatic control for controlling the amount of light emission in accordance with the distance to the subject is performed in controlling the strobe light. The flashmatic control changes the amount of light emission of the strobe in accordance with the distance to the subject, and is performed by the strobe light emitting means 42 and the flashmatic control means 43 as follows. That is,
Based on the distance signal obtained by the distance measuring means 30, the flashmatic control means 43 controls the strobe light emitting means 42
And the amount of light emitted to the subject is optimally controlled. In this case, highly accurate flashmatic control can be performed without being affected by the depth of field, which is suitable for an electronic camera having a large depth of field.

Here, it is possible to perform flashmatic control using the contrast method, but it is preferable to use the triangular distance measurement method as described above. Since focus adjustment by the contrast method does not directly measure the distance to the subject, some arithmetic processing is required after focusing to specify the distance by using the contrast method. The contrast method is slower in focus than the triangulation method, and requires more arithmetic processing to be used for flashmatic control. Therefore, the contrast method is more disadvantageous in terms of speed. Further, in the contrast method, since the depth of focus becomes deep particularly on the wide-angle side, a situation may occur in which the lens is in focus but an accurate distance cannot be specified. On the other hand, the triangulation method is a direct distance detection, and the detection speed is high. Therefore, the flashmatic control can be performed at high speed and with high accuracy by using this method.

It is also possible to select and use a triangulation method and a contrast method on the wide-angle side and the telephoto side. As described above, when the photographing lens 11 is set to a wider angle side than the predetermined value, the flashmatic control of the strobe light emitting means 42 is performed based on the distance signal obtained by the triangular distance measuring means 30. In addition, highly accurate flashmatic control can be performed without being affected by the depth of field.

However, when the photographing lens 11 is set on the telephoto side, if the triangular distance measuring means 30 is used, the amount of light emission may be insufficient and accuracy may not be maintained. Therefore, when the telephoto side is set, the flashmatic control of the strobe light emitting means 42 is performed based on the distance signal obtained based on the focus adjusting means by the contrast method. This enables highly accurate flashmatic control on both the wide-angle side and the telephoto side.

The flashmatic control includes:
As described above, the flash emission amount may be controlled according to the distance to the subject, but instead, the aperture of the photographing lens may be controlled according to the distance to the subject. Further, both of them may be controlled.

As described above, according to the present embodiment, focusing can be performed at high speed and with high accuracy by using both the active triangulation and the contrast. In the active triangulation method, focusing can be performed at high speed, but accuracy cannot be said to be sufficient. On the other hand, in the contrast method, focusing can be performed with high accuracy, but it takes time. Therefore, by using these two methods together, performing coarse positioning using the active triangulation method, and performing accurate positioning using the contrast method,
High-speed and high-precision focusing can be performed.

In this embodiment, the CCD 13 for image pickup is used.
In order to perform focusing by the contrast method from the image pickup output, it is not necessary to newly provide an image sensor, and the configuration can be simplified. Further, the distance measuring means 30 projects the infrared beam onto the subject a plurality of times in one ranging operation, and measures the subject distance based on a composite signal obtained as a result of the projections a plurality of times. Distance measurement can be performed with higher accuracy.

Further, by performing flashmatic control on the wide-angle side based on the distance signal from the distance measuring means and on the telephoto side based on the distance signal by the contrast method, the accuracy is improved over the entire range from the wide-angle side to the telephoto side. High flashmatic control becomes possible.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
FIG. 8 is a diagram for explaining a specific configuration of a focus adjustment mechanism in the electronic camera according to the embodiment and an operation principle thereof. The same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The present embodiment differs from the first embodiment in that the light receiving sections of the distance measuring means 30 are arranged on both sides of the light projecting section to form a so-called binocular AF. That is,
In the distance measuring means 30, PSDs 32a and 32b are respectively disposed at symmetrical positions on both sides of the LED 31,
A light receiving lens 35 for each PSD 32a, 32b
a and 35b are respectively arranged.

In the distance measuring means 30 of this embodiment, the LED 3
The light emitted from 1 passes through the projection lens 34 and the subject 50
And a projected spot image 51 is formed on the subject 50. This projected spot image 51 is formed by a light receiving lens 35a.
Is guided on the PSD 32a by the light receiving spot image 52a.
And its position is detected by the PSD 32a.
At the same time, the spot image 51 is
D32b to form a light receiving spot image 52b,
The position is detected by the PSD 32b. In the active triangulation control circuit 38, the two PSDs 32
The distance to the subject 50 is measured by averaging the respective detection outputs a and 32b.

FIGS. 5A and 5B are perspective views showing the structure of the focus adjusting mechanism in the present embodiment. The LED 31 and the PSDs 32a and 32b are integrally formed on an AF substrate 61, and are attached to a housing 62 having a light projecting lens 34 and light receiving lenses 35a and 35b. And it is arrange | positioned outside the lens system for photography.

In this example, as a countermeasure against low contrast, light 65 with a pattern is irradiated on the subject through a light projecting lens 66, and a subject image 67 at that time is captured by the CCD 13
Is imaged. In this case, even when the contrast of the subject is low, focusing by the contrast method can be performed. Means for irradiating patterned light include: (1) forming a pattern on the LED itself. (2) A grid pattern is arranged on the entire surface of the LED. (3) Form a grid pattern on the lens itself. Any of these may be adopted.

Here, the distance measuring means 3 as shown in FIG.
When 0 is used, as shown in FIG.
If the spot 2 is missing, the measurement by the distance measuring means 30 will be out of order. If the lens 11a is driven based on this erroneous measurement result and focusing is performed by the contrast method, a contrast peak cannot be obtained in the moving range of the lens 11a by the contrast method, and accurate focusing cannot be performed.

On the other hand, in the present embodiment, the PSDs 32 are arranged on both sides of the LED 31, so that the influence of the spot missing can be canceled out, and even if there is a spot missing, accurate distance measurement can be performed. In addition, since the amount of light is doubled, the S / N can be improved.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention.
FIG. 9 is a diagram showing a basic configuration of an active triangulation unit in the electronic camera according to the embodiment.

In the active triangulation, the moving distance of the light receiving spot position due to the change of the object position increases (the sensitivity increases) as the PSD installation position is farther from the photographing lens axis in the radial direction. The movement amount of the light receiving spot position due to the change is reduced (the sensitivity is lowered). If the PSD is arranged at a position close to the lens axis, measurement at a short distance is possible, but sufficient sensitivity cannot be obtained at a long distance, and the measurement cannot be performed. If the PSD is arranged at a position far from the lens axis, sufficient sensitivity can be obtained even at a long distance. On the other hand, at a short distance, the sensitivity is too high and the amount of movement of the spot light is too large to cover with the PSD.

On the other hand, in the present embodiment, as shown in FIG. 7A, different measurement systems are used for a short distance and a long distance. When the subject position is close, the light emitted from the LED 31a on the left side of FIG. 7A is irradiated on the subject, and the reflected light is detected by the PSD 32a. When the subject position is far, the right side of FIG. The light emitted from the LED 31b is applied to the subject, and the reflected light is detected by the PSD 32b. As a result, highly sensitive measurement can be performed regardless of the position of the subject.

Further, as shown in FIG.
By devising the arrangement positions of 1a, 31b and PSD 32, one PSD 32 can be used and the light receiving lens 35 can be shared by the two measurement systems.

(Fourth Embodiment) FIG. 8 shows a fourth embodiment of the present invention.
9 is a flowchart showing a focus adjustment operation of the electronic camera according to the embodiment.

In the present embodiment, the configurations of the electronic camera and the focusing mechanism are the same as those of the first embodiment, but the lens movement position in the coarse adjustment by the distance measuring means is different. That is,
Instead of moving to a focus position by active triangulation, the focus operation is speeded up by a contrast method by moving to a front focus or rear focus position.

In this embodiment, when the electronic camera is first released, active triangulation is performed as in the first embodiment (FIG. 2) (S1). Next, the CCD 13
The luminance of the subject is detected by the luminance detecting means 22 based on the image pickup output of (A), and it is determined whether the detected luminance of the subject is higher (high luminance) or lower (low luminance) than a predetermined luminance (S).
2). If it is determined that the brightness is high, the lens driving unit 14
Focus lens 11a based on the distance measurement data
Is driven, and the lens 11a is set to a second position different from the in-focus position (first position) (S3). This second
Is a position of the front pin or the rear pin slightly more than the first position.

Next, the hill-climbing AF by the contrast method is performed by moving the lens 11a starting from the second position obtained by the active triangulation means 22 (S4). Here, the lens 11a is moved in the direction of the subject when the focus is on the front focus, and the lens 11a is moved in the direction of the CCD when the focus is on the focus, so that the lens 11a is quickly moved to the contrast peak position. Can be set to That is, lens 1
The first movement direction of 1a can be set to the side on which focus is achieved, so that processing until a contrast peak is found can be simplified, and the focusing operation can be performed quickly.

When the lens 11a is set at the in-focus position by the distance measurement signal, the contrast may be lowered by the first movement of the lens 11a.
The movement direction of 1a must be reversed. On the other hand, as in the present embodiment, by setting the lens 11a to the position of the front focus or the rear focus according to the distance measurement signal, the contrast is always increased at the first movement of the lens 11a, so that unnecessary movement is eliminated. The hill-climbing AF can be performed quickly.

The amount of the front focus or the rear focus is such that the subject image is slightly blurred, specifically, relatively close to the in-focus position, and the subsequent movement of the hill-climbing AF reliably increases the contrast at the first movement. It is desirable to set it to such an extent that it can be determined. Since the amount of blur caused by the front focus or the rear focus changes depending on the focal length of the photographing lens and the lens aperture value, if the amount of the front focus or the rear focus is set to be the same, the change in the focal length of the photographing lens or the lens aperture value causes Therefore, the blur amount at the start of the focusing operation by the contrast method changes. Therefore, it is desirable to variably set the amount of the front focus or the rear focus according to the focal length of the photographing lens and the lens aperture value so that the blur amount at the start of the focusing operation by the contrast method is always the same. In this case, it is possible to perform hill-climbing AF more quickly by reducing unnecessary movement.

Next, the contrast of the subject is detected by the contrast detecting means 21 based on the image pickup output of the CCD 13, and it is determined whether the detected contrast is higher (OK) or lower (NG) than a predetermined value (S5). . O
If it is determined to be K, the process proceeds to a shooting operation (S6).

If the luminance is determined to be low in the luminance determination in S2, or if the contrast is determined to be NG in the contrast determination in S5, the lens 11a is moved to the first position which is the focus position based on the active triangulation data. Is driven. After that, the procedure moves to the photographing operation of S6. That is, when focusing by the contrast method is not successful, the focus adjustment is performed only by the active triangulation method.

As described above, in the present embodiment, the focusing operation by the contrast method is performed after the focus lens 11a is moved to the position of the front focus or the rear focus instead of the focus position by the active triangulation. Because
The focusing operation by the contrast method can be performed quickly, and higher-speed focusing can be performed.

(Fifth Embodiment) FIG. 9 shows a fifth embodiment of the present invention.
9 is a flowchart showing an automatic focus adjustment operation of the electronic camera according to the embodiment.

In this embodiment, the structures of the electronic camera and the focusing mechanism are the same as those in the first embodiment, but the lens moving speed in the two-stage focus adjustment is different.
That is, when moving to a focusing position by active triangulation, the lens moving speed is increased, and when moving to a focusing position by the contrast method, the lens moving speed is decreased.

First, when the camera is released, active triangulation is performed as in the first embodiment (FIG. 2) (S1). Then, the focusing lens 11a is driven at the first moving speed V1 based on the distance measurement data by the lens driving means 14, and the lens 11a is moved to the in-focus position (first focusing position).
Is set to 53) (S2).

Next, as in the first embodiment, the CCD
The luminance of the subject is detected by the luminance detecting means 22 based on the image pickup output of No. 13, and it is determined whether the detected luminance of the subject is higher (high luminance) or lower (low luminance) than a predetermined luminance (S3). If it is determined that the luminance is high, the hill-climbing AF by the contrast method is performed within a predetermined range centered on the first position 53 indicated by the active triangulation (S).
4). At this time, the lens 11a is moved at a second moving speed V2 (V2 <V1) lower than the first moving speed V1. As a result, the lens 11a is set at the position where the contrast peaks, that is, the focus position.

Next, the contrast of the subject is detected by the contrast detecting means 21 based on the image pickup output of the CCD 13, and it is determined whether the detected contrast is higher (OK) or lower (NG) than the predetermined value (OK). S5). If it is determined to be OK, the process proceeds to a shooting operation (S6).

If it is determined that the luminance is low in the luminance determination in S3, or if it is determined to be NG in the contrast determination in S5, the lens 11a is moved to the first position on the basis of the active triangulation data in the same manner as in S2. It is driven at the moving speed V <b> 1 and is set to the focus position (first position) 53.
After that, the procedure moves to the photographing operation of S6.

As described above, in the present embodiment, it is possible to further increase the speed by increasing the lens moving speed in the coarse adjustment by the active triangulation, and to decrease the lens moving speed in the fine adjustment by the contrast method. Thus, higher precision can be achieved.

(Sixth Embodiment) FIG. 10 is a flowchart showing a focusing operation of an electronic camera according to a sixth embodiment of the present invention.

In this embodiment, the configurations of the electronic camera and the focusing mechanism are the same as those in the first embodiment, but the lens movement position in the coarse adjustment by the distance measuring means is different, and the lens movement in the two-stage focus adjustment is further different. The speed is different. That is, the fourth embodiment and the fifth embodiment are combined.

First, when the electronic camera is released, active triangulation is performed as in the first embodiment (FIG. 2) (S1). Next, the luminance of the subject is detected by the luminance detecting means 22 based on the imaging output of the CCD 13,
It is determined whether the detected subject luminance is higher (high luminance) or lower (low luminance) than the predetermined luminance (S2). If it is determined that the luminance is high, the focusing lens 11a is driven at the first driving speed V1 by the lens driving unit 14 based on the distance measurement data, and the lens 11a is focused on the triangular distance (the first position). ) Is set to a second position different from (2) (S3). This second position is a position of the front pin or the rear pin slightly more than the first position.

Next, the hill-climbing AF by the contrast method is performed by moving the lens 11a starting from the first position indicated by the active triangulation (S).
4). At this time, the lens 11a is moved at a second moving speed V2 (V2 <V1) lower than the first moving speed V1.

Here, the lens 11a is moved in the direction of the subject when the focus is on the front focus and the lens 11a is moved in the direction of the CCD if the focus is on the focus with respect to the in-focus position by the active triangulation. The position can be set quickly. That is, lens 1
The first movement direction of 1a can be set to the side on which focus is achieved, so that processing until a contrast peak is found can be simplified, and the focusing operation can be performed quickly.

Next, the contrast of the subject is detected by the contrast detecting means 21 based on the image pickup output of the CCD 13, and it is determined whether the detected contrast is higher (OK) or lower (NG) than a predetermined value (OK). S5). If it is determined to be OK, the process proceeds to a shooting operation (S6).

If the brightness is determined to be low in the brightness determination in S2, or if it is determined to be NG in the contrast determination in S5, the lens 11a is moved at the first moving speed V1 based on the active triangulation data. It is driven and set to a first position which is a focus position by triangulation.
After that, the procedure moves to the photographing operation of S6. That is, when focusing by the contrast method is not successful, the focus adjustment is performed only by the active triangulation method.

As described above, in the present embodiment, similarly to the fourth embodiment, the focusing lens 11 is not located at the in-focus position by the active triangulation, but at the position of the front focus or the rear focus.
Since the focusing operation by the contrast method is performed after moving a, it is possible to quickly perform the focusing operation by the contrast method, and to achieve faster focusing. Further, as in the fifth embodiment, in the coarse adjustment by active triangulation, the lens moving speed can be further increased by increasing the lens moving speed, and in the fine adjustment by the contrast method, the lens moving speed can be reduced. Thus, higher precision can be achieved.

(Seventh Embodiment) FIG. 11 is a diagram showing a main configuration of an electronic camera according to a seventh embodiment of the present invention. The same parts as those in the first embodiment (FIG. 1) are denoted by the same reference numerals, and detailed description thereof will be omitted.

This embodiment is different from the first embodiment in that a sub CPU 70 having a communication means 71 is provided, and the distance measuring means 30 can be operated independently.

FIG. 12 is a flowchart showing the focusing operation in this embodiment.

First, it is checked whether or not the touch sensor attached to the release button of the camera is turned on.
Check at 0 msec (S1). When the touch is detected, power is supplied to a camera (such as a CCD). Then, photometry is performed (S2), and WB (white balance) is adjusted (S3).

Next, when the 1st release (the shutter switch has two steps, a shallow depression is referred to as a 1st release and a full depression is referred to as a 2nd release) is turned on, the active triangulation starts. This is performed (S5). In this active triangulation, detection data obtained by 16 light projections are combined and averaged.

Next, based on the triangulation output, the lens 11a is moved to a position just before the in-focus position (front focus) (S11).
6). Thereafter, the contrast peak is detected in the range of six frames by the contrast method, and the lens 11a is moved to the peak position (S7). Then, it is determined whether or not the peak detection is successful (S8).

Here, in parallel with the lens movement based on the triangulation output and the focusing operation by the contrast method,
Perform active triangulation again. In this active triangulation, since the focusing operation by the contrast method is slow, the distance measurement by the light emission 16 times is performed three times, and the distance measurement data is integrated four times together with the distance measurement by S5. The distance is calculated to measure the distance to the subject (S9).
This parallel processing is performed by the sub CPU 7 as shown in FIG.
This is possible because 0 is provided.

If the peak detection in S8 is NG, S
The lens 11a is driven based on the distance measurement data in Step 9 (S10). That is, if focusing by the contrast method is not successful, focusing is performed based on four distance measurement data (64-time projection data) by triangulation. If the peak detection in S8 is OK, furthermore, after performing the focusing operation in S10, a flashmatic operation is performed based on the projection data 64 times (S11). Thus, the amount of light emission of the strobe is optimally controlled according to the distance to the subject.

Then, when the first release is kept ON (S12), and when the second release is also turned ON (S13), the photographing is started (S14). When the first release is turned off in S12, the process returns to the start. If the first release is ON and the second release is OFF, wait until the second release is ON.

As described above, according to the present embodiment, as in the first embodiment, focusing can be performed at high speed and with high accuracy by using both the active triangulation method and the contrast method. . Furthermore, CCD for imaging
In order to perform focusing by the contrast method from the 13 imaging outputs, it is not necessary to newly provide an imaging element, and the configuration can be simplified.

In addition to the above, in the present embodiment, the output signals obtained by a plurality of triangulations (a total of four rangings by 16 projections) are integrated, so that an output signal having a good S / N ratio is obtained. , A highly accurate distance signal can be obtained, and highly accurate flashmatic control can be performed. Also,
If focusing by contrast method does not work,
Since the focusing operation is performed based on the high-accuracy distance signal obtained by a plurality of triangulations, focusing can be performed with higher accuracy than in the case of one triangulation.
In addition, when the lens is driven based on the focus adjustment unit based on the contrast method, the object is irradiated with infrared beams a plurality of times to perform active triangulation, so that the overall distance measurement time becomes longer. No inconvenience.

The present invention is not limited to the above embodiments, but can be implemented in various modifications without departing from the spirit of the invention.

[0102]

As described above in detail, according to the present invention, the focusing operation of the taking lens is performed by using both the contrast method and the triangulation active distance measurement method, so that the focus can be quickly and accurately adjusted. It can be performed. In addition, since the image sensor of the electronic camera is also used as the sensor used for the contrast method, the configuration for adjusting the focus is simplified.

Also, after driving to the position of the front focus or the rear focus (the second position) by a predetermined amount with respect to this focus position instead of the focus position (first position) by the active triangulation means, Since the focus adjustment is performed by driving the photographing lens based on the focus adjusting means using the contrast method, the focusing operation using the contrast method can be performed quickly, and the focus adjustment can be performed at a higher speed.

When it is determined that the brightness of the subject is low or lower than a predetermined value, the photographing lens is driven to the in-focus position (first position) based on the distance measurement output of the active triangulation means to adjust the focus. To prevent the accuracy of the automatic focus adjustment by the contrast method under low brightness from decreasing,
High-speed and high-precision automatic focusing can be performed.

[Brief description of the drawings]

FIG. 1 is an exemplary view showing a main configuration of an electronic camera according to a first embodiment.

FIG. 2 is a view for explaining a specific configuration of a focus adjustment mechanism and an operation principle thereof according to the first embodiment;

FIG. 3 is a flowchart illustrating a focus adjustment operation according to the first embodiment.

FIG. 4 is a view for explaining a specific configuration of a focus adjustment mechanism and an operation principle thereof in the electronic camera according to the second embodiment.

FIG. 5 is a perspective view illustrating a configuration of a focus adjustment mechanism according to a second embodiment.

FIG. 6 is a diagram for explaining a problem when spot missing occurs in a received light spot image.

FIG. 7 is a diagram showing a basic configuration of an active triangulation unit in an electronic camera according to a third embodiment.

FIG. 8 is a flowchart illustrating a focus adjustment operation of the electronic camera according to the fourth embodiment.

FIG. 9 is a flowchart showing a focus adjustment operation of the electronic camera according to the fifth embodiment.

FIG. 10 is a flowchart illustrating a focus adjustment operation of the electronic camera according to the sixth embodiment.

FIG. 11 is a diagram showing a main configuration of an electronic camera according to a seventh embodiment.

FIG. 12 is a flowchart illustrating a focus adjustment operation and flashmatic control according to a seventh embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Photography lens 12 ... Lens aperture 13 ... Solid-state image sensor (CCD) 14 ... Lens drive means 15 ... Zoom drive means 16 ... Aperture control means 20 ... Digital process circuit 21 ... Contrast detection means 22 ... Luminance detection means 30 ... Distance measurement Means 31 ... Infrared LED 32 ... Position detecting element (PSD) 34 ... Light projecting lens 35 ... Light receiving lens 38 ... Active triangulation circuit 41 ... System controller 42 ... Strobe light emitting means 43 ... Flashmatic control means 44 ... LCD 45 memory Card 50: Subject 51: Projected spot image 52: Received spot image 53: Focus position by active triangulation 54: Focus position by hill climbing AF 55: Focus position of subject 56: Contrast curve 57: Contrast peak 61: AF board 62 ... Housing 65 ... with pattern Light 66 ... projection lens 67 ... object image

Continued on front page F-term (reference) 2H011 AA03 BA14 BA33 BB02 BB04 CA21 DA01 2H051 AA00 BA47 BB20 CB22 CB26 CC17 CC19 CE14 DA02 DA22 DC17 EA29 EB02 FA38 FA48 5C022 AA13 AB15 AB24 AB66 AC03 AC42 AC54 AC69 AC74

Claims (4)

[Claims] A photographing lens for forming a subject image; an image sensor for converting the subject image formed by the photographing lens into an image signal; Active triangulation means for measuring, focus adjustment means by a contrast method for performing focus adjustment using a high-frequency component of an output signal in a predetermined area of the image sensor, and the photographing lens is measured by the active triangulation means. After driving a predetermined amount of front focus or rear focus with respect to the in-focus position, and driving the photographic lens based on the focus adjustment means based on the contrast method to perform focus adjustment. An automatic focusing device for an electronic camera, comprising: 2. A photographing lens for forming a subject image, an image pickup device for converting a subject image formed by the photographing lens into an image signal, and a subject luminance detecting means for detecting luminance of the subject. An active triangulation means for projecting light to a subject to measure a subject distance of the subject; a focus adjustment means for performing a focus adjustment using a high-frequency component of an output signal in a predetermined area of the image sensor; When the brightness of the subject is determined to be higher than or equal to a predetermined brightness by the subject brightness detecting means, the photographing lens is moved forward by a predetermined amount with respect to the in-focus position based on the distance measurement output of the active triangulation means. After driving to the position of the rear focus, the photographing lens is driven based on the focus adjusting means based on the contrast method to perform focus adjustment, and the subject brightness is equal to or less than a predetermined value. When it is determined that the brightness is low, the photographing lens drive control means for driving the photographing lens to a focus position based on the distance measurement output of the active triangulation means to adjust the focus. An automatic focus adjustment device for an electronic camera, characterized in that: 3. An automatic focus adjusting device for an electronic camera according to claim 1, wherein said subject brightness detecting means detects the brightness of the subject based on an output signal of said image pickup device. . 4. The automatic focus of an electronic camera according to claim 1, wherein the amount of the front focus or the rear focus is an amount depending on a focal length or an aperture value of a photographing lens at the time of photographing. Adjustment device.