JP2003114378A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously photograph several subjects positioned at different photographing distances, in a camera for focusing by introducing a contrast method. SOLUTION: After finishing scanning all the ranges, a peak value for actual photographing is selected out of estimation values obtained from several range finding areas, and then, continuous photographing is performed by a single release operation based on the selected peak value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera that performs a focusing operation by a contrast method using an image pickup signal of an image pickup device.

[0002]

2. Description of the Related Art Conventionally, there is a method called a contrast method as an AF method for cameras. With this method,
An image of a subject is picked up by an image pickup device such as a CCD, and the in-focus position is determined using an image pickup signal in the focus detection area. The image pickup signal in the area is passed through a bandpass filter (BPF) to extract a component of a predetermined spatial frequency band. Then, by integrating these absolute values within the area, the focus evaluation value for performing the focusing operation is obtained. The focus evaluation value represents the magnitude of contrast, and the highest focus is at the peak of the focus evaluation value. That is, the peak position is the in-focus position. When looking for this peak,
A conventionally known climbing focus operation is performed to find the peak.

By the way, in such distance measurement, the signal of the focus detection area described above is used to measure the shooting distance to the subject. However, depending on the subject, which is the main one when there are a plurality of persons in front and behind. You may be confused about the subject. That is, even if there is only one focus detection area, a plurality of subjects may enter the same area depending on the composition of the shooting. Further, even in the case of so-called multi-point distance measurement having a plurality of focus detection areas, one area is selected from the plurality of areas when photographing, and the same inconvenience as in the case of one focus detection area is eventually obtained. Occurs. As a method of solving this, Japanese Patent Laid-Open No. 8-318785 discloses a method of calculating a defocus amount for each focus detection area in AF of a phase difference method and performing continuous shooting based on the defocus amount.

[0004]

However, the above disclosed method cannot cope with the case where a plurality of subjects exist in the same area, and the defocus amount up to the subjects must be calculated one by one, which makes the algorithm complicated. Next, the hardware and software become complicated, and the time lag until shooting increases.

An object of the present invention is to provide a camera which performs a focusing operation by a contrast method using an image pickup signal of an image pickup element, and which is capable of continuous photographing in which a plurality of subjects having different photographing distances are focused. To do.

[0006]

In order to solve the above problems, the invention of claim 1 provides an image pickup device for picking up a subject image through a taking lens, a lens driving means for driving the taking lens, and Evaluation value calculation means for calculating a focus evaluation value based on an image pickup signal output from an image pickup element, and the focus from the evaluation value calculation means output as the lens driving means drives the photographing lens. A peak value detecting means for detecting a peak of the evaluation value; a peak value selecting means for selecting a plurality of peak values corresponding to a lens position to be actually photographed from the output of the peak value detecting means; a release means; Based on one operation of the release means, there is provided an image taking execution means for driving the taking lens at a plurality of peak positions based on the output from the peak value selecting means to take an image respectively. Preparative have characterized, it is possible to obtain an image in focus each for a plurality of main subject within the photographing angle of view with in a single shooting operation. Further, in that case, as described in claim 2, without calculating the distance to the subject one by one, simply set the peak position of the evaluation value obtained when the focus lens is driven from the close end to the infinite end. This objective is easily achieved simply by driving the lens.

The invention of claim 3 is characterized in that the peak value selecting means selects a plurality of peak values from the same distance measuring area, and the invention of claim 4 is that the peak value selecting means is The feature is that a plurality of peak values are selected from different distance measuring areas. That is, not only a plurality of peaks in the same area but also peak values existing in a plurality of areas can be continuously captured.

Further, according to the invention of claim 5, since the camera further comprises a distance measuring area selecting means for selecting the plurality of distance measuring areas, an area which is known to be unnecessary in advance is excluded. It becomes possible. The invention according to claim 6 is characterized in that the peak value selecting means selects the maximum peak value of the peak values of the respective areas of the plurality of distance measuring areas. Can be imaged.

According to a seventh aspect of the present invention, the photographing execution means is
Since the photographing is performed in order from the peak position based on the output of the peak value selecting means near the end point of the photographing lens, the driving direction of the photographing lens is always kept in a fixed direction, and the movement at the time of photographing is not affected. There is no waste. Further, according to the invention of claim 8, the end point of the photographing lens is the closest end of the photographing lens, and the photographing is performed with priority from a range in which a main subject is likely to exist. Further, claim 9
Then, select multiple peak values from the same ranging area,
In the tenth aspect, a plurality of peak values are selected from different distance measuring areas.

According to an eleventh aspect of the present invention, the camera further comprises setting means for setting the maximum number of shots taken by the shooting executing means, and prevents the number of shots from being unnecessarily increased. In the invention of claim 12, of the plurality of peak values,
The selection is performed in the descending order of the value, that is, in the descending order of the contrast of the subject. Further, in the selection, in claim 13, a plurality of peak values are selected from the same distance measuring area, and in claim 14, a plurality of peak values are selected from different distance measuring areas.

According to a fifteenth aspect of the present invention, the peak value selecting means discriminates a maximum peak value from a plurality of peak values output by the peak value detecting means, and the peak value is equal to or more than a predetermined value with respect to the previous maximum peak value. Since a peak value having a value is selected from the plurality of peak values, a low level peak value which is not so important is excluded, and the number of shots can be reduced. Further, in claim 16, the camera further calculates a focal depth of the photographing lens according to an aperture value at the time of photographing, and a plurality of plural peak values output from the peak value detecting means are included in the focal depth. A representative lens position determining means for determining one representative lens position representative of the plurality of lens positions when there is a lens position is provided, and the lens position determining means according to claim 17, The lens position corresponding to the maximum peak position among the plurality of peak positions corresponding to the lens position is defined as the representative lens position, and
Then, since the average value of the lens positions is used as the representative lens position, the number of shots can be reduced.

According to a nineteenth aspect of the present invention, the camera further comprises recording control means for recording a plurality of image signals photographed by the photographing execution means in an external storage medium detachable from the camera. Further in item 20,
It is characterized in that it includes selection recording control means for selecting whether or not to record the plurality of image signals photographed by the photographing execution means on the recording medium, so that the photographer finally selects an image to be recorded on the recording medium. You can do it.

According to the twenty-first aspect of the present invention, the photographing execution means terminates the photographing operation for the plurality of peak positions by interrupting the release operation by the release means. If you want to stop the shooting, you can immediately stop shooting. Further, according to the invention of claim 22, the execution of the photographing can be ended by the earlier of the interruption of the release operation and the reaching of the maximum number of photographed images, which provides a camera with excellent usability.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram of an AF (autofocus) digital camera according to an embodiment of the present invention. The taking lens 101 is a zoom lens and is driven by the driver 113 in the optical axis direction. Here, the driver 113 includes a zoom drive mechanism of a zoom lens and a drive circuit thereof, and a focus drive mechanism of a focusing lens and a drive circuit thereof, each of which is a CPU.
Controlled by 112.

The taking lens 101 forms a subject image on the image pickup surface of the image pickup element 103. The image pickup element 103 is a photoelectric conversion image pickup element that outputs an electric signal according to the light intensity of the subject image formed on the image pickup surface, and a CCD type or MOS type solid state image pickup element is used. The image sensor 103 is driven by a driver 115 that controls the timing of signal extraction. A diaphragm 102 is provided between the taking lens 101 and the image sensor 103. The diaphragm 102 is driven by a driver 114 including a diaphragm mechanism and a drive circuit thereof. The image pickup signal from the solid-state image pickup device 103 is input to the analog signal processing circuit 104, and the analog signal processing circuit 104 performs correlated double sampling processing (CDS).
Etc. are processed. The image pickup signal processed by the analog signal processing circuit 104 is converted from an analog signal to a digital signal by the A / D converter 135.

The A / D converted signal is subjected to various image processing such as contour compensation and gamma correction in the digital signal processing circuit 106. The digital signal processing circuit also includes a luminance / color difference signal generation circuit for recording. The buffer memory 105 is a frame memory that can store data for a plurality of frames captured by the image sensor 103, and the A / D converted signal is temporarily stored in the buffer memory 105. Digital signal processing circuit 106
Then, the data stored in the buffer memory 105 is read and each processing described above is performed, and the processed data is stored again in the buffer memory 105. The CPU 112 is connected to the digital signal processing circuit 106, the drivers 113 to 115, etc., and controls the sequence of camera operations. CP
The AE calculation unit 1121 of U112 performs automatic exposure calculation based on the image signal from the image sensor, and the AWB calculation unit 11
At 22, white balance adjustment calculation is performed. The band pass filter (BPF) 1124 extracts a high frequency component in a predetermined band based on the image pickup signal in the focus detection area provided in the image pickup area. In addition, when a plurality of focus detection areas are set, the signals in each area are sequentially read, and the extraction processing for each area is performed by the bandpass filter (BPF) 1124.

The output of the BPF 1124 is input to the next evaluation value calculator 1125, where the absolute value of the high frequency component is integrated and calculated as a focus evaluation value. The AF calculation unit 1126 uses the contrast method to calculate A based on these focus evaluation values.
F calculation is performed. The CPU 112 adjusts the focusing lens of the taking lens 101 by using the calculation result of the AF calculation unit 1126 to perform the focusing operation. The operation unit 116 connected to the CPU 112 has a power switch 1161 for turning on / off the power of the camera, a full-push switch 1162 and a half-push switch 1163 that are turned on / off in conjunction with a release button, and settings for selecting a shooting mode or the like. Button 116
4. A selection button 1165 for actually recording the continuously shot images in the external memory is provided. When these switches or buttons are operated, a signal corresponding to the operation is sent to the CPU 1
12 is input.

The CPU 112 also has a storage unit for storing various data, and the peak value of the evaluation value, the corresponding lens position, etc. are stored therein. The image data that has been subjected to various kinds of processing by the digital signal processing circuit 106 is temporarily stored in the buffer memory 105, and then recorded in the external storage medium 111 such as a memory card via the recording / reproducing signal processing circuit 110. When recording image data in the storage medium 111, generally, a predetermined compression format, for example, JP
Data compression is performed by the EG method. The recording / playback signal processing circuit 110 performs data compression when recording image data in the external storage medium 111 and data decompression processing when reading compressed image data from the storage medium 111. The recording / reproducing signal processing circuit 110 also includes an interface for performing data communication with the storage medium 111.

The monitor 109 is a liquid crystal display device for displaying a captured subject image, and is also used when reproducing and displaying image data recorded in the storage medium 111. When displaying an image on the monitor 109, the image data stored in the buffer memory 105 is read out, and D /
The A converter 108 converts the digital image data into an analog video signal. Then, an image is displayed on the monitor 109 using the analog video signal.

In the contrast method, there is a correlation between the degree of blurring of an image and the contrast, and the contrast of the image is maximized when there is a focus. The size of the contrast can be evaluated by the size of the high frequency component of the image pickup signal. That is, BPF1
A high-frequency component of the image pickup signal is extracted by 124, and the evaluation value calculation unit 1125 integrates the absolute value of the high-frequency component to obtain a focus evaluation value. As described above, the AF calculation unit 1126 performs AF calculation based on this focus evaluation value. CPU11
Reference numeral 2 adjusts the focusing lens position of the photographing lens 101 using the calculation result of the AF calculation unit 1126 to perform the focusing operation.

Next, among the operations of the camera, the operations relating to the continuous shooting of the present invention will be described based on the flowcharts of FIGS. In this embodiment, assuming that the power switch 1161 of FIG. 1 is turned on and the continuous shooting mode of the present invention is set by the setting button 1164, the processing of the flow shown in FIGS. 2 and 3 is started. First, step S100
When the half-push switch 1163 is turned on with step S1
In 01, the taking lens is moved to the initial position. The initial position may be either the infinity side end position or the closest end position.

Steps S102 to S1 in FIG.
In the processing up to 06, the focus evaluation value is sampled over the entire lens position. First, in step S102, the movement of the focusing lens of the taking lens 101 is started. In this embodiment, the lens position is moved from the closest end position to the infinity end position. Step S10
The image pickup signal is read out from the CCD 103 in step S103 almost at the same time as the movement of the lens 2 and the A / D converter 1
A / D conversion of the image pickup signal is performed by 35. Step S
At 104, the evaluation value calculation unit 1125 performs integration within an area based on the signal processed by the BPF 1124 for the image pickup signal within the predetermined focus detection area. The results are stored in the storage unit 1123 as a pair with the lens position at the time of sampling. In step S105, it is determined whether or not the lens position has reached the infinity position. If it is determined in step S105 that the position is at infinity, the process proceeds to step S106 to stop the lens driving. On the other hand, if it is determined in step S105 that the position is not at infinity, the process returns to step S103, and the focus evaluation value is calculated and stored again. Therefore, step S
By the processing of 102 to step S106, the focus evaluation value is stored in the storage unit 1123 for each sample position between the closest position to the infinity position of the focusing lens.

Next, in step S107 of FIG.
The peak value of the focus evaluation value stored in 123 and the lens position corresponding thereto are selected. 4 to 6 are diagrams showing a method of this selection. FIG. 4 shows a case where there is one focus detection area, and as a result of driving the lens over the entire area, peaks (p1, p2, p3) are respectively found at three lens positions (x1, x2, x3). ing.
In FIG. 4, the reference level R is further set in order to eliminate the peak p3 which is not so meaningful for recording even if it is found as a peak. Where R = K
-In p2, K is a constant such that K <1. That is, p3, which is a level equal to or lower than a predetermined amount with reference to the maximum evaluation value
Exclude. In addition, when the objects to be photographed are originally only low-contrast objects, the maximum peak value (here, p2) itself may be considerably low, and it may be considered that such a method of determining R does not make sense. In such a case, it is better not to determine the reference level R by such a relative value but to set it to a certain constant value.

FIG. 5 shows a case where there are two focus detection areas, and the lens positions x corresponding to the peak values p1, p2 and p3 which are equal to or higher than the reference level R as in the case of FIG.
1, x2 and x3 are selected. In addition, in the case of FIG. 5, the selection lens positions may be all three positions described above, but when there are many focus detection areas, the number of images to be shot increases and the time until the end of shooting increases, The maximum peak position (x1, x3 in FIG. 5) of each focus detection area may be selected. Alternatively, the maximum number of shots may be set with the setting button 1164, and the shot peaks may be selected in descending order of the peak value, or the shot peaks may be selected in the order of the peak position closest to the peak. FIG. 6 shows a case where a plurality of peak positions (x2, x3 in FIG. 6) are detected within the depth of focus (Δx) corresponding to the aperture value at the time of shooting. In that case, only the maximum peak position (here, x2) may be selected, or the average position (x4 = (x1 + x2) / 2) of a plurality of lens positions corresponding to a plurality of peaks may be selected.

Next, returning to FIG. 3, if the photographing lens position is selected in step S107 by the above-described method, the lens is moved to the selected position in step S108, and the shutter button is fully pressed in step S109. Start shooting. Here, as a method of moving the lens in step S108, shooting is performed in order from the selected position close to the closest end where the main subject is likely to exist, and is stored in the buffer memory in step S110. Next, in step S111, it is confirmed whether or not the shutter button is fully pressed, and if it is continuously pressed, the next step S1 is performed.
In step 12, it is determined whether all selected positions have been completed. If shooting at all selected positions has not been completed, the process returns to step S107 to select the next shooting position. If the photographing has been completed for all the selected positions or if it is detected in step S111 that the shutter button has been fully pressed, the process proceeds to the next step S113.
In step S113, an image to be written in the external memory is selected using the selection button 1165 and the monitor 109, only the selected image is recorded in the external memory in step S114, and a series of sequences is completed.

In the above-described embodiments, the digital camera has been described as an example, but the present invention can be applied to a silver halide film camera as long as the object is imaged by the image sensor and AF is performed by the contrast method.

[0027]

As described above, in the present invention, the photographing lens is driven over the entire area, a plurality of peaks of focus evaluation values are detected by the contrast method, and a plurality of peaks of focus evaluation values are continuously detected at a plurality of corresponding lens positions. I tried to shoot. As a result, even when the main subject is at a plurality of different photographing positions, it is possible to photograph the subject desired by the photographer in focus.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an AF digital camera according to the present invention.

FIG. 2 is a flowchart showing the operation of the camera according to the present invention.

FIG. 3 is a flowchart showing a process following the flowchart of FIG.

FIG. 4 is an explanatory diagram of selecting a peak value from within the same area.

FIG. 5 is an explanatory diagram of selecting a peak value from a plurality of areas.

FIG. 6 is an explanatory diagram showing that there are multiple peaks within the depth of focus.

[Explanation of symbols]

101 shooting lens 102 aperture 103 CCD 104 Analog signal processing circuit 105 buffer memory 106 digital signal processing circuit 112 CPU 113-115 driver 116 Operation part 135 A / D converter 1161 power switch 1162 full-press switch 1163 Half-press switch 1164 setting button 1165 selection button 1123 storage unit 1124 bandpass filter 1125 Evaluation value calculation unit 1126 AF calculation unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideomi Hibino             Marunouchi 3 2-3 No. 3 shares, Chiyoda-ku, Tokyo             Ceremony Company Nikon (72) Inventor Toshiaki Maeda             Marunouchi 3 2-3 No. 3 shares, Chiyoda-ku, Tokyo             Ceremony Company Nikon (72) Inventor Masaru Ota             Tokyo Stock Exchange 1-325, Futaba 1-32             Company Nikon technical workshop F term (reference) 2H011 BA35 BB03 CA24                 2H051 BA47 BA66 CE14 CE16 DA22                       DA28 DD10 EA10                 5C022 AA13 AB29 AB66 AC03 AC69                       AC74

Claims (22)

[Claims] 1. An image pickup device for picking up a subject image through a photographing lens, a lens driving means for driving the photographing lens, and an evaluation value calculation means for calculating a focus evaluation value based on an image pickup signal output from the image pickup device. A peak value detecting means for detecting a peak of the focus evaluation value from the evaluation value calculating means output when the lens driving means drives the photographing lens, and an output of the peak value detecting means. Based on the output from the peak value selecting means, based on one operation of the peak value selecting means for selecting a plurality of peak values corresponding to the lens positions to be actually photographed, the release means, and the releasing means. A camera comprising: a photographing execution unit that drives a photographing lens to a plurality of peak positions to perform photographing. 2. The camera according to claim 1, wherein the lens driving means drives the taking lens over the entire range from the closest end to the infinite end of the taking lens. 3. The camera according to claim 1, wherein the peak value selecting means selects a plurality of peak values from the same distance measuring area. 4. The camera according to claim 1, wherein the peak value selecting means selects a plurality of peak values from different distance measuring areas. 5. The camera according to claim 4, wherein the camera further comprises distance measuring area selecting means for selecting the plurality of distance measuring areas. 6. The camera according to claim 4, wherein the peak value selecting means selects the maximum peak value of the peak values in each of the plurality of distance measuring areas. 7. The photographing execution means executes the photographing purely from a peak position based on an output of the peak value selecting means near an end point of the photographing lens.
The camera described in. 8. The camera according to claim 7, wherein the end point of the taking lens is the closest end of the taking lens. 9. The camera according to claim 8, wherein the peak value selecting means selects a plurality of peak values from the same distance measuring area. 10. The camera according to claim 8, wherein the peak value selecting means selects a plurality of peak values from different distance measuring areas. 11. The camera according to claim 1, wherein the camera further comprises setting means for setting the maximum number of shots taken by the shooting executing means. 12. The camera according to claim 1, wherein the peak value selecting means selects from a plurality of peak values by the peak value detecting means in descending order of the value. 13. The camera according to claim 12, wherein the peak value selecting means selects a plurality of peak values from the same distance measuring area. 14. The camera according to claim 12, wherein the peak value selecting means selects a plurality of peak values from different distance measuring areas. 15. The peak value selecting means discriminates a maximum peak value from a plurality of peak values output by the peak value detecting means, and a peak value having a value equal to or more than a predetermined value with respect to the previous maximum peak value. The camera according to claim 1, wherein is selected from the plurality of peak values. 16. The camera further calculates a focal depth of the photographing lens according to an aperture value at the time of photographing, and a plurality of lens positions corresponding to a plurality of peak values output from the peak value detecting means within the depth of focus. The camera according to claim 1, further comprising: a representative lens position determining unit that determines one representative lens position representative of the plurality of lens positions in the case of occurrence. 17. The lens position determining means sets a lens position corresponding to a maximum peak position among the plurality of peak positions corresponding to the plurality of lens positions as the representative lens position. The camera described in. 18. The camera according to claim 16, wherein the lens position determining means sets an average value of the plurality of lens positions as the representative lens position. 19. The camera according to claim 1, further comprising recording control means for recording a plurality of image signals photographed by the photographing execution means in an external storage medium detachable from the camera. . 20. The recording control means according to claim 19, further comprising selection recording control means for selecting whether or not to record a plurality of image signals photographed by the photographing execution means on the recording medium. Camera. 21. The camera according to claim 1, wherein the photographing executing means ends the photographing of the plurality of peak positions by interrupting the release operation by the releasing means. 22. The camera further comprises setting means for setting the maximum number of images to be captured by the image capturing execution means, and the release operation is interrupted by the release means and the maximum number of images is reached, whichever comes first. 22. The camera according to claim 21, wherein the execution of the photographing is ended.