JPH0318181A - Automatic focus device - Google Patents

Abstract

PURPOSE:To attain optimum focus adjustment by acting selectively a 1st focus adjustment means suitable for continuous image pickup operation and a 2nd focus adjustment means suitable for discontinuous image pickup operation. CONSTITUTION:The automatic focus device is provided with a processing circuit 1 as 1st and 2nd focus adjustment means and a mode changeover switch 8 as a selection means selecting the 1st and 2nd focus adjustment means. The 1st focus adjustment means moves sequentially a relative position between a focusing lens 2 and an imager 3 in an increasing direction of contrast information in output picture information by the imager 3 and is used at the continuous image pickup of the camera. The focus adjustment means is used at the discontinuous image pickup of the camera and sets the relative position between the lens 2 and the imager 3 to a position obtaining prescribed contrast information in the scanning area.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an automatic focusing device, specifically, a continuous image and a
The present invention relates to an automatic focusing device installed in a non-continuous still image capturing camera, such as a movie/still camera, a continuous/still mode still camera, or a movie camera with a one-shot function.

[Conventional technology]

In recent years, movie video cameras have become popular for general home use, as well as photographic lenses used in various electronic still cameras released by various manufacturers.
The imaging device and a part of the video signal processing circuit each have the same functions. Therefore, by sharing them, it is possible to realize a movie/still electronic camera that is compactly integrated and cost-effective. Therefore, the dual-purpose camera disclosed in Japanese Patent Application Laid-Open No. 55-165077 has a structure in which a photographing lens, an imaging device, a video signal processing circuit, etc. are shared.

In the dual-purpose camera mentioned above, the focusing device poses a problem. Conventional automatic focusing (hereinafter referred to as AF) devices for cameras include those that use a dedicated AF detection element and those that use image data from an imager (hereinafter referred to as imager) as an AF signal. be. Then, the imager AF that uses the imager signal drives a focusing lens while detecting the degree of alignment based on the AF signal,
The mountain-climbing imager AF determines the peak point of the degree of focus as the in-focus point, and after scanning the entire range of the lens and comparing and measuring the degree of focus, the above-mentioned lens is again moved to a predetermined point determined based on comprehensive judgment. There is a scanning type imager AF that drives the camera to take pictures.

[Problem to be solved by the invention]

In order to realize an electronic camera that can be used as a movie/still camera as described above, when used as a movie camera and a still camera, an AP that matches the respective shooting conditions is required.
It is essential to have the functionality.

However, the technique disclosed in the above-mentioned Japanese Patent Laid-Open No. 55-165077 does not provide any technical proposals regarding the focusing device. Therefore, with the technique disclosed above, it is not possible to realize a movie/still camera having an automatic focusing function.

As a focusing device for the above-mentioned dual-purpose camera, the above-mentioned AF means having a detection element dedicated to AF can measure the degree of focus independently of the image, and is easy to use. However, in the above-mentioned dual-purpose electronic camera using an imager such as a CCD, an imager AF type is sometimes more suitable for cost reasons in the performance limit range. However, even if either the mountain-climbing type or scanning type of Imager AF described above is applied as an AF device for a movie/still camera, movie shooting is continuous shooting, and still shooting is one-shot shooting. It is not possible to satisfy the performance of both. For example, movie/
If the above-mentioned mountain-climbing AF is used as a focusing device for a still camera, the time required for focusing will be long for still photography.
Furthermore, there is a problem in that when the speed is increased, out-of-control operation is more likely to occur.

The purpose of the present invention is to solve the above-mentioned problems,
The automatic focusing system is equipped with F-class shooting functions, and has two focus adjustment means corresponding to each, and by allowing the appropriate selection, it is possible to fully satisfy both shooting functions. It is to provide the focus equipment.

[Means and effects for solving the problem] The automatic focusing device of the present invention has an aspect in which the relative position of the focusing lens and the imager is sequentially moved in a direction in which contrast information in the image information output by the imager increases. First match: J! The scanning in which the relative position of the first focusing adjustment means for performing the focusing adjustment operation in the J-section mode, the same focusing lens, and the same imager as described above is scanned over substantially the entire predetermined change range. In the second focusing adjustment mode, the relative position of the focusing lens and the imager is set to a position where predetermined contrast information is obtained within the scanning area based on the contrast information obtained at various positions within the scanning area. The present invention is characterized in that it comprises a second focus adjustment means for performing the operation, and a selection means for selectively causing the first focus adjustment means or the second focus adjustment means to function.

[Example] The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 is a block diagram of an automatic focusing device showing an embodiment of the present invention. This automatic focusing device is installed in a movie/still electronic camera. and,
When the camera is used in a movie shooting mode (hereinafter referred to as M mode) in which continuous video shooting is performed, it is a so-called mountain-climbing imager that performs a tracking type focusing operation in the first focusing adjustment mode. When the first focusing adjustment means of the AF is further used in a still shooting mode (hereinafter referred to as S mode) in which discontinuous shooting is performed, the scanning imager AF is used as the second focusing: Iu2J node mode. A certain second focusing section 21 is selected and activated by a mode changeover switch 8.

The configuration of this automatic focusing device includes an AF data processing circuit 1a for AF processing, an AF data storage section 1b, and a comparison circuit 1c.
, a system controller 1 containing a judgment circuit 1d and an AF processing program in M and S modes, a lens group 2 including a focusing lens 2a, a motor driver 4 for a motor that drives the focusing lens 2a, and a lens group. an imager 3 that outputs an imaging signal based on the imaging light flux from 2; an S/H circuit 5 that is a sample/hold circuit for the imaging signal; ，
According to the S mode, the video circuit 6 outputs video signals to each recording device and the output of the S/H circuit 5 is A/D converted, and the digital image output is sent to the AF data processing circuit 1a manually. It is further comprised of an A/D conversion circuit 7, and a mode changeover switch 8, which is means for selecting the M and S modes.

The AF data processing circuit 1a receives contrast information (hereinafter referred to as contrast value), which is a value obtained by separating high frequency components of the digital image data output from the A/D conversion circuit 7, and indicates the degree of matching. Calculate.

The AF data storage section 1b stores the contrast value calculated by the processing circuit 1a. Further, the comparison circuit 1C is a circuit that compares the contrast value calculated by the AF data processing circuit 1a and the contrast value of the AF data storage section 1b according to instructions of an AF processing routine in each mode to be described later. Further, the judgment circuit 1d similarly determines whether the focus lens 2
This is used to determine whether to drive the lens a or to complete focusing.

Regarding the operation of the fish matching device of this embodiment configured as described above, the flowcharts of the AF routine shown in FIGS. A case where the contrast value is as shown in FIG. 4 will be explained. The driving position of the focusing lens 2a is determined by dividing the lens position corresponding to the distance from the closest lens into a predetermined number of stages, and the number of stages is expressed as the number of lens driving stages n. And the closest position is the number of stages n-0,
The ao position is the number of stages nmn. The setting of this stage max number position is the closest position as Qmn, and the (X) position as ■
Controlling as ax nswo does not particularly change the gist of the present invention.

First, the mode selection switch 8 selects M mode, that is,
When the movie shooting mode is selected, the M mode AF processing routine shown in FIG. 2 is called in response to an AF operation command from the shooting samurai. The focusing lens 2a is driven in either direction relative to the imager 3 at an arbitrary position, and the contrast value of the image data calculated by the AF data processing circuit 1a is compared with the contrast value at the immediately previous lens driving position. It is determined whether or not the amount has increased (step S101). It is assumed that the contrast value at the immediately previous lens position is stored in the AF data storage section 1b. And if the contrast value increases,
It is further driven in the same direction (step S102), and it is determined again whether the contrast value has increased. If the value increases further, the process returns to step S102 and is repeated until the contrast value no longer increases.

Then, when the contrast value stops increasing, it is determined that the peak point has been reached, the lens drive is stopped, a focus completion display is displayed, and the routine processing is ended.

For example, if point E in FIG. 4 is set as the driving start point of the focus lens 2a, processing will be performed according to the above routine,
The contrast value diagram is traced in the direction of the arrow from point E, and when the peak point C of the contrast value is reached, it is assumed that focusing is completed.

On the other hand, if the contrast value does not increase in step S101 in the above AF routine, step S
Jump to 103. Then, drive the lens in the opposite direction and check whether the contrast value increases or decreases. If the value increases, the process returns to step S102. If the value does not increase, the process returns to Pj and step S103, and driving in the opposite direction is performed. Then, when the drive circuit reaches a predetermined number of times, it stops driving the lens, displays an indication that focusing is not possible, and ends the process.

Note that, for example, if the S/H of the imaging signal is poor under low illumination, or if the contrast value is abnormally large due to large blurring of the lens, a state of disorder occurs in this process, and the cycle of returning to step 8103 is repeated. Focusing may become impossible, so when setting the focusing sensitivity and focusing speed, it is necessary to fully consider the effects of disturbances on the object and the stability of the response operation. When this AF processing routine ends and returns to the main routine shooting process, this AF processing routine always monitors the contrast value for restart, except when the so-called focus lock state is set in the main routine. The device is placed in a standby state that continues.

As described above, the M mode AF process has a feedback control element, and can track and focus on a moving subject from any position. Therefore, it can be said to be suitable for continuous tracking photography of a subject, such as when shooting a movie.

On the other hand, the mode selection switch 8 selects S mode, that is,
When the still photography mode is selected, the S mode AF processing routine shown in FIG. 3 is called by the AF operation command of the photography sequence.

First, the focusing lens 2a is driven to an initial position, that is, a close position where the number of drive stages n is 0, and at the same time the number of stages n is reset to 0. Then, the contrast value of the image data at that time is calculated by the AF data processing circuit 1a, and A
The data is stored in the F data storage unit 1b as data d (n) (step S201).

Then, the focusing lens 2a is driven in the positive direction by one step relative to the imager 3, and the number of steps n is incremented. The value of the number of stages n is the final number of stages nIaX” position)
Unless it exceeds , the process returns to step S201, and the contrast values for each scanning position of each lens are sequentially stored in the AF data storage section 1b.

Then, when the focusing lens is caused to scan over the entire area and the number of stages becomes n>n, the lens drive described above is stopped. Then, the above stored data d
(n), the step number corresponding to the maximum value of data d (n) is set to M, and the focusing lens 2a is driven to the step number position M to complete focusing, and the routine ends. Control is then returned to the photographing scene and photographing is performed. Note that the above routine shows the case where the contrast value is stored in the storage unit 1b as an array variable, but
Of course, the contrast values may be compared at the time of storage, and only the contrast value and step number of the larger value may be stored.

To explain the above process using the example of the contrast value diagram in FIG. , the number of steps at the ψ position n. Reach ax. and,
The maximum point D of d (n) is searched, and M, which is the number of stages corresponding to it and indicates the focused point, is determined.

As described above, the AF processing by the S mode processing routine has an open control form and searches for the highest in-focus point in substantially the entire scanning range, so there is no unstable element in the operation. Furthermore, since the AF operation ends when the lens is driven again to the above-mentioned combined black point, it can be said that the AF is more suitable for one-shot still photography than for movie photography. With mountain-climbing AF, the focusing time changes depending on conditions such as the condition of the subject and the large blur of the lens, and in some cases it may take a considerable amount of time or the operation may become unstable.
This AF process always provides high-speed focusing for a certain period of time,
It can be said to be ideal for still photography.

In addition, in the S mode processing in the above embodiment, the final in-focus point is set at the state of maximum contrast, but there are of course various methods other than this for determining the final in-focus point by comprehensively judging the contrast information within the scanning area. Something is possible. For example, as a process when there are multiple contrast value peaks within the scanning area, the number n of lens drive stages corresponding to each peak is changed to P, , P2,
P ......Pk, select the above P as the number of stages 3' of the final combined sunspot, or set the above PK to 1 or upper g(5P - P l, :Oite(P one!
:Jr1iLx-)l k l
Various methods can be considered, such as selecting the peak point that exists closest to the stage number PI1 when the value of 2 is the minimum, that is, the intermediate position of the total number of drive stages.

Next, details of the mode changeover switch 8 for the M and S modes of the camera equipped with the automatic fish matching device of the above-described embodiment will be explained with reference to FIG. It is assumed that the configuration of the mode selector switch 8 is such that the two switches 8a and 8b are operated in the order of the switches 8a to 8b by suppressing their actuators. The output terminal of the switch 8a is connected to one input terminal of the NOR circuit 8d via a mono multi-by-break (MMV) 8c, while the switch SW8b is connected to the other input terminal of the NOR circuit 8d. The output terminal of the NOR circuit 8d is connected to the mode detection terminal 8g. Further, the output end of the switch 8b is branched and connected to a recording trigger terminal 8h. Resistors 8e and 8f are each pull-up resistors.

The mode detection terminal 8g and the recording trigger terminal 8h are connected to the system controller 1, respectively. Then, by operating the switch, the mode detection terminal 8g goes high.
When the level changes and a falling trigger is output from the recording trigger terminal 8h, S mode photography is selected, and when the mode detection terminal 8g remains unchanged and remains at the L level,
It is assumed that when a falling trigger is output to the recording trigger terminal 8h, M mode photography is selected and a recording start command is given to the controller 1.

The operation of the mode changeover switch S configured as above will be explained. The mode selection is made by distinguishing between S mode and M mode depending on whether the actuators of switches 8a and 8b are pressed quickly or slowly, and when selecting S mode for one-shot shooting, press the switch quickly. The switch is pressed slowly to select the M mode in which images are taken continuously for a certain period of time. When specifying the S mode, quickly press the actuators of switches 8a and 8b as described above. First, the switch 8a is turned on,
The MMV 8c outputs an L level pulse with a constant width, but since the switch is pressed quickly, the switch 8b is also turned on during the time within the pulse width. Therefore, the mode detection terminal 8g becomes H level, and at the same time the recording trigger terminal 8g becomes H level.
When the switch 8b is turned on, a trigger signal is output to h, and a command to start recording of S-mode photography is given to the system controller 1.

On the other hand, when selecting M mode, switches 8a, 8
Slowly press the actuator b.

First, the switch 8a is turned ON, and a constant width pulse of L level is output from the MM 8c. However, since the actuator is pressed slowly, by the time the switch 8b is turned ON, the above-mentioned pulse of the MM 8c is already output. The L level pulse has returned to H level, and no signal is output from the NOR circuit 8d. Therefore, the S mode detection terminal 8g remains at the H level, only a trigger is output from the recording trigger terminal 8h, and the system controller 1 is given an M mode photographing and recording start command. Note that when the system controller 1 receives a command to start photographing in each of the above modes, photographing control starts, and in response to the focusing command, the AF routine of the automatic focusing device of the most advanced embodiment is called.

Next, a circuit of a mode changeover switch as a modification of the mode changeover switch 8 will be explained with reference to FIG. The mode changeover switch of this modification has switches 9a and 9b each having an actuator that is operated continuously, and the terminal of the switch 9a is connected to a T-type flip-flop 9.
The output terminal of a flip-flop 9c, which is connected to the input terminal of C and changes between H and L levels each time the switch 9a is turned on, is connected to the mode detection terminal 9f. Also switch 9b
The terminal is connected to the recording trigger output terminal 9g. The terminals 9f and 9g are each connected to the system controller 1, and when a trigger is output to the recording trigger terminal 9g while the mode detection terminal 9f is at H level, the system controller 1 starts recording S mode shooting. death,
Also, when the terminal 9f is at L level, the recording trigger terminal 9g
It is assumed that recording of M mode photography is started when a trigger is output. Incidentally, when the power is turned on, the mode detection terminal 9f connected to the output terminal of the T-type flip-flop 9C is reset to L level.

To explain the operation of the modified mode changeover switch configured as above, first, the first switch 9a,
By pressing 9b, the mode detection terminal 9f becomes H level, a trigger is output to the recording trigger terminal 9g, the S mode is designated, and photographing and recording is started. Furthermore, by suppressing the switches 9a and 9b for the second time, the mode detection terminal 9f returns to the L level, a trigger is similarly output to the recording trigger terminal 9g, the M mode is designated, and shooting and recording is started. Become. Thereafter, when the switches 9a and 9b are operated, the above operation is repeated.

An image of a movie/still camera using the automatic fish matching device of the above embodiment @! As the recording medium, a combination of magnetic tape/magnetic disk, magnetic disk, magneto-optical disk, etc. are used, and the recording device for these is either a TL4M built-in device or an external device. and so on. In addition to the movie/still camera described above, the automatic focusing device of the present invention can also be applied to electronic still cameras having continuous/still shooting modes, movie cameras with a one-shot shooting function, and the like.

In addition, it does not necessarily have to be associated with the camera's shooting mode; for example, even with a camera dedicated to still photography, the switch can be used to select M, M, or It may be configured to be able to switch between both S and S modes.

[Effects of the Invention] As described above, the automatic focusing device of the present invention has a first focusing adjustment mode in which automatic focusing can be performed by constantly tracking changes in subject distance, and a stable high-speed operation. Since the advantages of both the executable second focus adjustment mode can be selectively applied as required, the optimal focus adjustment operation can be performed no matter what kind of shooting operation the camera performs. .

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of an automatic focusing device showing one embodiment of the present invention, FIG. 2 is a flowchart of the M mode FAF processing routine of the eye movement focusing device shown in FIG. 1, and FIG. 1 is a flowchart of the S-mode AF processing routine of the automatic focusing device shown in FIG. 1, FIG. 4 is a graph of the contrast value of a subject, used to explain the automatic focusing device shown in FIG. 1, and FIG. 1 is a circuit diagram of the mode changeover switch of the automatic focusing device shown in FIG. 1, and FIG. m6 is a circuit diagram showing a modification of the mode changeover switch of the automatic fishing device shown in FIG. 1. 2a... Focusing lens 3...
...imager

Claims (2)

[Claims] (1) A first mode for performing a focus adjustment operation in a first focus adjustment mode in which the relative position between the focusing lens and the imager is sequentially moved in a direction in which contrast information in the image information output by the imager increases. Based on the contrast information obtained at various positions during scanning, the relative positions of the focusing adjustment means, the same focusing lens, and the imager are scanned over substantially the entire predetermined change range. a second focus adjustment means for performing a focus adjustment operation in a second focus adjustment mode in which the relative position of the focusing lens and the imager is set to a position where predetermined contrast information is obtained within the scanning area; An automatic focusing device comprising a selection means for selectively activating the first focus adjustment means or the second focus adjustment means. (2) The selection means causes the first focus adjustment means to function when the camera performs continuous shooting operations,
2. The automatic focusing device according to claim 1, wherein said second focusing means is activated when said camera performs discontinuous photographing operations.