JP4086975B2 - Focus adjustment operation control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a focus adjustment operation control device that performs focus adjustment by moving a photographing lens in the optical axis direction.
[0002]
[Prior art]
2. Description of the Related Art Conventional focus adjustment operation control devices are known that detect a subject image divided in two by a line sensor and determine whether or not the photographing lens is in the in-focus position based on the shift amount of these images. . The focus position actually has a predetermined width, and in the focus adjustment operation, the photographing lens is controlled to fall within the focus width.
[0003]
[Problems to be solved by the invention]
If the focus width is set to be narrow to increase the focusing accuracy, a hunting phenomenon may occur in which the photographic lens reciprocates around the focus width, and it may take a long time to be positioned at the focus position. There is. On the other hand, if a wide focus range is set, the time until the photographic lens is set at the focus position is shortened, but the accuracy of the focus position is not necessarily high, and sufficiently high focus accuracy can be obtained. Is difficult.
[0004]
The present invention aims at providing the prescribed smoothly in-focus position of the photographing lens, and a high focus obtain harmony of obtaining accurate focusing operation control device.
[0005]
[Means for Solving the Problems]
The focus adjustment operation control apparatus according to the present invention includes an optical sensor that detects a subject image and outputs a pixel signal corresponding to the subject image, and a defocus calculation unit that calculates a defocus amount of the photographing lens based on the pixel signal. A focus state determination means for determining a focus state of the photographing lens based on a defocus amount, a first focus width, and a second focus width narrower than the first focus width; A photographic lens driving unit that moves the photographic lens along the optical axis direction based on the amount and prohibits the movement of the photographic lens on the condition that the focusing state determining unit determines that the photographic lens is in a focused state; And the focus determining means determines that the photographic lens is in the focus position when the defocus amount is within the second focus width, and the defocus amount is within the second focus width. Defocus amount when not in If it is necessary to reverse the direction of movement of the photographic lens in order to enter the second focus range, and the defocus amount is within the first focus range, the photographic lens is in the in-focus position. It is characterized by judging.
[0006]
The first focus width is determined based on, for example, the open F value of the photographing lens and the minimum circle of confusion. The second focus width is obtained, for example, by multiplying the first focus width by a predetermined reduction magnification.
[0007]
Preferably, when the defocus amount is not included in the second focus range, the focus determination unit needs to maintain the moving direction of the photographing lens so that the defocus amount is included in the second focus range. If there is, it is determined that the taking lens is not in the in-focus position.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an electrical configuration of a camera provided with a focus adjustment operation control apparatus according to an embodiment of the present invention.
[0009]
This camera is a single-lens reflex camera and includes a camera body 100 and an interchangeable lens (photographing lens) 200 that can be attached to and detached from the camera body 100. In the camera body 100, a pentaprism 102 constituting a part of the finder optical system is disposed above the quick return mirror 101 and has passed through a plurality of lens groups 201 and 202 provided in the interchangeable lens 200. The light beam is guided to the eyepiece lens of the finder optical system via the quick return mirror 101 and the pentaprism 102 and enters the photometric sensor 103. Further, the light beam that has passed through the lens groups 201 and 202 is reflected by the sub mirror 104 attached to the lower surface of the quick return mirror 101 and applied to the focus detection sensor 300 that is a CCD line sensor provided below the quick return mirror 101. Led.
[0010]
Each circuit provided in the camera body 100 is controlled by a camera control circuit (CPU) 110 including a microcomputer. The camera control circuit 110 is connected to the peripheral circuit 120. In addition to the photometric sensor 103, the peripheral circuit 120 is connected to a motor drive circuit 121, an exposure mechanism 122, and an aperture mechanism 123. The motor drive circuit 121 is provided to drive a mirror motor 124 that changes the tilt angle of the quick return mirror 101 and to drive a winding motor 125 that winds up the film. The exposure mechanism 122 drives a shutter (not shown), and the diaphragm mechanism 123 adjusts the opening of a diaphragm (not shown).
[0011]
A motor drive circuit 130 is connected to the camera control circuit 110. The motor drive circuit 130 drives the AF motor 131, and a gear block 132 is connected to the AF motor 131. The gear block 132 is coupled to a gear block 203 provided in the interchangeable lens 200 via a joint mechanism (not shown). The lens group 201, 202 can be moved in the optical axis direction by the gear block 203, thereby adjusting the focus state of the subject image. That is, these lens groups 201 and 202 are focusing lens groups. On the other hand, an encoder 133 is connected to the output shaft of the AF motor 131, and the pulse signal output from the encoder 133 is counted by a counter 111 provided in the camera control circuit 110, thereby obtaining the amount of lens movement.
[0012]
The peripheral circuit 120 is provided with a D / A converter 126, and a voltage signal Vagc for determining an output level in the focus detection sensor 300 is input to the focus detection sensor 300 via the D / A converter 126. A pixel signal (VIDEO) output from the focus detection sensor 300 is input to the A / D converter 112 of the camera control circuit 110, and is used to adjust the focus by driving the lens groups 201 and 202.
[0013]
The camera control circuit 110 is connected to an automatic manual (AF / MF) switch 141, a release switch 142, a photometric switch 143, and a main switch 144. An automatic / manual (AF / MF) switch 141 is provided to determine whether focus adjustment is performed manually or automatically. The release switch 142 is turned on by fully depressing a shutter button (not shown), whereby a photographing operation is executed. The metering switch 143 is turned on by half-pressing the shutter button, whereby an automatic focus adjustment operation (AF operation) is executed. The main switch 144 is a switch for permitting the operation of the camera.
[0014]
A display device 145 and a nonvolatile memory (EEPROM) 146 are connected to the camera control circuit 110. The display device 145 is provided to display the shooting mode, shutter speed, and the like. The EEPROM 146 stores data necessary for focus detection.
[0015]
In the interchangeable lens 200, a lens control circuit (lens CPU) 204 that communicates information and the like unique to the interchangeable lens with the camera body 100 is provided for control such as automatic focus adjustment (AF).
[0016]
2 and 3 are flowcharts of a main routine for performing overall control of the operation of the camera of this embodiment. This main routine starts by attaching a battery to the camera.
[0017]
In step S101, the system is initialized, and various parameters are set to initial values. In step S102, power-down processing is performed, and processing for minimizing battery power consumption is performed. The power-down process is executed, for example, when the main switch 144 is in an off state or when the shutter button is not operated for a predetermined time.
[0018]
In step S103, it is determined whether or not the photometric switch 143 (FIG. 1) is turned on. While the photometric switch 143 is in the OFF state, the process returns to step S102. On the other hand, when the shutter button is half-pressed and the photometry switch 143 is turned on, the process proceeds to step S104, a power-on process is executed, and power is supplied to each circuit in the camera.
[0019]
In step S105, a timer is started. In step S106, a switch check is performed, and the switching state of switches such as the (AF / MF) switch 141 is checked. In step S107, lens communication is performed, and various information such as the F value of the lens is transmitted between the lens control circuit 204 and the camera control circuit 110. In step S108, AE (automatic exposure) calculation processing is performed, and an aperture value and a shutter speed are determined. In step S109, display processing is performed, and the aperture value, shutter speed, and the like are displayed on the display device 145.
[0020]
In step S111, AF processing is performed. That is, according to the AF processing routine shown in FIG. 4, if the photometric switch 143 (FIG. 1) is in the ON state, the lens groups 201 and 202 are driven to perform focus adjustment. In step S112, it is determined whether or not a predetermined loop time has elapsed since the timer start in step S105. The loop time is 100 ms, for example. Before the loop time elapses, steps S111 and 112 are repeatedly executed. When the loop time elapses, the process proceeds to step S113.
[0021]
In step S113, it is determined whether or not the photometric switch 143 is on. When the photometric switch 143 is on, the process returns to step S105. That is, steps S106 to S112 are executed again, and focus adjustment is performed for about 100 ms.
[0022]
On the other hand, when the photometric switch 143 is switched to the off state, it is determined whether or not the power hold flag is 1 in step S114. The power holding flag is 0 unless it is set to 1 in step S116. When the power hold flag is 0, step S115 is executed, the power hold timer is started, and the power hold time is started. In step S116, the power hold flag is set to 1.
[0023]
In step S117, it is determined whether the power hold time has elapsed since the timer start in step S115. Until the power hold time elapses, the process returns to step S105, and the above-described operation is performed. When the power hold time elapses, the process proceeds from step S117 to step S118. That is, during the power hold time, the power-on state is maintained regardless of which switch is operated. When the power hold time has elapsed, the power hold flag is set to 0 in step S118, and step S102 is executed. Power down processing is performed.
[0024]
FIG. 4 is a flowchart of the AF processing routine executed in step S111 of FIG.
In step S201, it is determined whether or not the photometric switch 143 is on. When the photometry switch 143 is in the OFF state, the AF lock flag is set to 0 in step S202, and this routine ends.
[0025]
On the other hand, when it is determined in step S201 that the photometry switch 143 is in the on state, the process proceeds to step S203, where it is determined whether or not the AF lock flag is 1. The AF lock flag is set to 1 in step S209 when the in-focus state is obtained, but is normally 0. When the AF lock flag is 1, this routine ends. However, when the AF lock flag is 0, the process proceeds to step S204, and a defocus calculation is performed.
[0026]
When the lens groups 201 and 202 are thus driven and the in-focus state is obtained, after the AF lock flag is set to 1 in step S209, the AF processing routine continues as long as the photometry switch 143 is on. Only steps S201 and S203 are executed and the process ends. That is, driving of the lens groups 201 and 202 is prohibited (focus lock). In this state, when the photometric switch 143 is switched to the OFF state, the AF lock flag is switched to 0 in step S202, and the focus lock is released.
[0027]
In step S204, the focus detection sensor (CCD line sensor) 300 (FIG. 1) performs integration operation, that is, charge accumulation to detect one line of the subject image, and the analog pixel signal for one line is a digital pixel signal. Is converted to The defocus amount is calculated based on the pixel signal for one line and stored in the memory. In step S204, the direction in which the lens groups 201 and 202 should move is also obtained as a result of the defocus calculation.
[0028]
In step S205, the defocus amount obtained in step S204 is read from the memory, and it is determined whether or not it is within a predetermined focus range. In step S206, based on the result of the focus check in step 205, it is determined whether or not an in-focus state has been obtained. When the in-focus state is not obtained, pulse calculation is executed in step S207, and the amount by which the lens groups 201 and 202 should move to the in-focus position is obtained based on the defocus amount. In step S208, the lens groups 201 and 202 are actually driven and moved by the movement amount obtained in step S207. In step S210, the driving directions of the lens groups 201 and 202 are stored in the memory, and the AF processing routine ends. On the other hand, when it is determined in step S206 that the in-focus state is obtained, the AF lock flag is set to 1 in step S209, and the AF processing routine ends.
[0029]
FIG. 5 is a flowchart of the focus check routine executed in step S205 of FIG.
[0030]
In step S301, the first focus width is obtained from equation (1).
1st focus width = open F value x minimum circle of confusion (1)
For example, when the open F value is 2 and the minimum circle of confusion is 30 μm, the first focus width is 60 μm.
[0031]
In step S302, the second focus width is obtained from equation (2).
Second focus width = first focus width × reduction magnification (2)
The reduction magnification is 0.5, for example, and the second focus width is narrower than the first focus width.
[0032]
In step S303, the second focus width is determined as the focus width. In step S304, a first movement direction that the lens groups 201 and 202 are moved to the front of the check focus current focus, and a second movement direction lenses groups 201 and 202 is to be moved is either in the same direction It is determined whether the direction is reverse. When the direction is the reverse direction, the first focus width is determined as the focus width in step S305, and when the direction is the same direction, step S305 is skipped. That is, the focus width is determined to be the second focus width if the first movement direction and the second movement direction are the same, and the first focus is determined if the first movement direction and the second movement direction are opposite. Determined by width.
[0033]
In step S306, it is determined whether or not the defocus amount obtained in step S204 of FIG. 4 is smaller than the focus width. When the defocus amount is smaller than the focus width, the focus flag is set to 1 in step S307, and when the defocus amount is equal to or greater than the focus width, the focus flag is set to 0 in step S308. The focus check routine ends. The focus flag is used in step S206 in FIG. That is, in step S206, if the in-focus flag is 1, it is determined that the in-focus state is obtained, and if the in-focus flag is 0, it is determined that the in-focus state is not obtained.
[0034]
FIG. 6 shows four examples of the focus adjustment operation of this embodiment.
Example 1) shows a case where the photographing lens moves in the first movement direction from the far distance side toward the in-focus position FP and stops in the first in-focus range (reference A1). In this case, in step S204 of the AF processing routine, it is required that the taking lens should be further moved in the same direction by a predetermined amount. Therefore, in the focus check routine, the process proceeds from step S304 to step S306, and the focus check is performed based on the second focus width. Here, since the defocus amount is larger than the focus width, step S308 is executed, and the focus flag is set to zero.
[0035]
Therefore, in the AF processing routine, the process proceeds from step S206 to step S207, and the next moving amount of the photographing lens is obtained. As a result, in step S208, the photographic lens is moved to the second focusing width (reference A2), and the AF processing routine ends. Next, when the AF processing routine is executed, in step S204, it is required that the photographing lens should be further moved by a predetermined amount in the same direction. Therefore, in the focus check routine, the process proceeds from step S304 to step S306, and the focus check is performed based on the second focus width. In this case, since the photographing lens is in the second focusing range (reference A2), the focusing flag is set to 1. Accordingly, in the AF processing routine, the process proceeds from step S206 to step S209, and the focus adjustment operation ends.
[0036]
In Example 2), the photographic lens moved in the first movement direction from the far side toward the in-focus position FP, and stopped within the first in-focus width (reference A3) beyond the second in-focus width. Shows the case. In this case, in step S204 of the AF processing routine, it is required that the photographing lens should be moved by a predetermined amount in the second movement direction opposite to the first movement direction. Therefore, in the focus check routine, the process proceeds from step S304 to step S305, and the first focus width is selected. That is, in step S306, an in-focus check is performed based on the first in-focus width, and the photographing lens is in the first in-focus width. Therefore, the in-focus flag is set to 1 in step S307. Therefore, in the AF processing routine, the process proceeds from step S206 to step S209, and the focus adjustment operation ends.
[0037]
Example 3) shows a case where the photographic lens moves in the first movement direction from the long distance side toward the focusing position FP and stops at a position exceeding the first focusing width (reference A4). In this case, in step S204 of the AF processing routine, it is required that the photographing lens should be moved by a predetermined amount in the second movement direction. Therefore, in the focus check routine, the process proceeds from step S304 to step S305, and the first focus width is selected. In step S306, the focus check is performed with the first focus width as a reference. Here, since the photographing lens is outside the first focus width, the focus flag is set to 0 in step S308.
[0038]
Accordingly, in the AF processing routine, the process proceeds from step S206 to step S207, and the moving amount of the photographing lens is obtained. In step S208, the photographing lens moves in the second movement direction. By this movement, the photographing lens stops within the first focusing width (reference A5), and the AF processing routine ends. Next, when the AF processing routine is executed, in step S204, it is required that the photographing lens should further move by a predetermined amount in the second movement direction. Therefore, in the focus check routine, the process proceeds from step S304 to step S306, and the focus check is performed based on the second focus width. In this example, since the taking lens is outside the second focus range, the focus flag is set to 0 in step S308. Accordingly, in the AF processing routine, steps S207 and S208 are executed, and the photographing lens moves in the second movement direction. The AF processing routine ends with the photographing lens stopped in the second focus range (reference A6).
[0039]
Next, when the AF processing routine is executed, in step S204, it is required that the photographing lens should be further moved by a predetermined amount in the second movement direction. Therefore, in the focus check routine, the process proceeds from step S304 to step S306, and the focus check is performed based on the second focus width. Since the photographic lens is within the second focus range, the focus flag is set to 1 in step S307. That is, in the AF processing routine, the process proceeds from step S206 to step S209, and the focus adjustment operation ends.
[0040]
Similarly to Example 3), in Example 4), the photographing lens moves in the first movement direction from the far side toward the in-focus position FP, and stops at a position beyond the first in-focus width (reference A7). Shows the case. That is, in step S204 of the AF processing routine, it is required that the photographic lens should move by a predetermined amount in the second movement direction. In the focus check routine, the first focus width is selected in step S305, and in step S306, the focus check is performed based on the first focus width. Here, since the photographing lens is outside the first focus width, the focus flag is set to 0 in step S308.
[0041]
Accordingly, in the AF processing routine, the process proceeds from step S206 to step S207, and the moving amount of the photographing lens is obtained. In step S208, the photographing lens moves in the second movement direction. By this movement, the photographic lens stops beyond the second focus width and within the first focus width (reference A8), and the AF processing routine ends. Next, when the AF processing routine is executed, in step S204, it is required that the photographic lens should reversely move by a predetermined amount in the first movement direction. Therefore, in the focus check routine, step S305 is executed, and the focus check is performed based on the first focus width. That is, in the AF processing routine, the process proceeds from step S206 to step S209, and the focus adjustment operation ends.
[0042]
As described above, in this embodiment, in order to move the photographing lens within the second focusing width which is a relatively narrow focusing width, when the moving direction has to be reversed, the photographing lens is relatively If the zoom lens is within the first focus range, which is a wide focus range, the photographic lens is considered to be in the focus position. Therefore, according to the present embodiment, it is possible to prevent the occurrence of a hunting phenomenon in which the photographing lens repeats reciprocating movement in order to put the photographing lens in the focusing range, and the time required for the focus adjustment operation can be shortened. In this embodiment, when the photographing lens moves in the same direction, the second focus width is used as a reference for focus detection, so that high focus accuracy can be obtained.
[0043]
【The invention's effect】
As described above, according to the present invention, the photographing lens can be smoothly set at the in-focus position, and high in-focus accuracy can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an electrical configuration of a camera provided with a focus adjustment operation control apparatus according to an embodiment of the present invention.
FIG. 2 is a first half of a flowchart of a main routine that performs overall control of the operation of the camera.
FIG. 3 is the latter half of the flowchart of the main routine.
FIG. 4 is a flowchart of an AF processing routine.
FIG. 5 is a flowchart of a focus check routine.
FIG. 6 is a diagram showing four examples of the focus adjustment operation of the present embodiment.
[Explanation of symbols]
200 Photography lenses 201 and 202 Lens group 300 Optical sensor

Claims (4)

An optical sensor that detects a subject image and outputs a pixel signal corresponding to the subject image;
Defocus calculation means for calculating a defocus amount of the photographing lens based on the pixel signal;
A focus state determination means for determining a focus state of the photographing lens based on the defocus amount, the first focus width, and the second focus width narrower than the first focus width;
The photographing lens is moved along the optical axis direction based on the defocus amount, and movement of the photographing lens is prohibited on the condition that the in-focus state determination unit determines that the in-focus state is determined. Photographing lens driving means for
The focus state determination unit determines that the photographing lens is in a focus position when the defocus amount is within the second focus range, and the defocus amount is the second focus range. If the defocus amount is not within the second focus range, it is necessary to reverse the moving direction of the photographic lens so that the defocus amount is within the second focus range, and the defocus amount is the first focus range. If it is in the lens, it is determined that the photographing lens is in a focus position.   2. The focus adjustment operation control device according to claim 1, wherein the first focus width is determined based on an open F value of the photographic lens and a minimum circle of confusion.   The focus adjustment operation control device according to claim 2, wherein the second focus width is obtained by multiplying the first focus width by a predetermined reduction magnification. When the defocus amount is not within the second focus range, the focus state determination unit is configured to move the photographing lens in order to put the defocus amount within the second focus range. 2. The focus adjustment operation control device according to claim 1 , wherein if it is necessary to maintain the focus, it is determined that the photographing lens is not in a focus position.

Images