JP3280484B2 - Focus correction mechanism for autofocus SLR cameras - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-lens reflex camera with interchangeable photographic lenses, and more particularly, to a mechanism for correcting the in-focus position of an AF single-lens reflex camera of a back focus control type.

[0002]

2. Description of the Related Art At present, no AF single-lens reflex camera on the market employs a focus correction mechanism, and generally employs an AF control system by driving a dedicated lens. Therefore, when the AF single-lens reflex camera intentionally corrects the in-focus position, once the in-focus operation is performed, M
This requires a complicated operation of switching to the F photographing mode and allowing manual operation, and rotating the distance ring of the lens for correction.

[0003]

Recently, the adoption of AF in single-lens reflex cameras has become widespread, and has reached the high-end camera market. However, while the convenience of the AF camera has been recognized, professionals still have questions about the AF operation, and the conventional manual camera or high-quality AF single-lens reflex camera
It is often used in F shooting mode.
In the AF operation of the AF camera, the focus state is determined by the physical detection method, whereas the focus state intended by the photographer often differs depending on the scene, and the focus state by the AF operation is not necessarily the photographer's focus state. This is because the screen is not satisfactory. SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to focus on an AF operation in which focusing is quicker than manual operation, and to quickly correct a focus state after the AF operation to a state intended by a photographer. It is to provide a correction mechanism.

[0004]

In order to achieve the above object, a focus correction mechanism of an autofocus single lens reflex camera according to the present invention comprises a camera body front block including at least a photographing lens and a lens mount for the photographing lens; A camera body rear block including a film opening, a front body front block and a camera body rear block, a front-rear block connecting portion that adjusts the distance between the front and rear blocks, and the camera based on AF information. An auto-focus single-lens reflex camera comprising an AF drive mechanism for adjusting a distance between a lens mount of a front block of the main body and an opening of a rear block, and configured to focus by adjusting a flange back of the photographing lens. In the AF shooting mode, press the release button. When pressed, it starts the focusing operation, when it reaches the focal point by the flange back adjustment, of the external operation unit to allow moving the flange back forward or backward in the vicinity of the focus point by the external operation unit Once
Move the focus plane forward or backward by a small unit Δf
When the external operation unit is operated N times in the same direction,
It is configured such that the focus plane can be corrected by nΔf or + nΔf .

Further, according to the present invention, in the above configuration, the MF mode is selected when the camera is in the MF photographing mode or during the AF focusing operation.
When switched to the photographing mode, the flange back position can be arbitrarily moved by the external operation unit.
Further, in the above configuration according to the present invention, the external operation unit includes:
An FB correction lever, one end of which is an axis, and the other end of which is swingable to the left and right. The release button is operated with a forefinger, and the thumb is positioned on the back of the camera body. Is placed on the top or back of the camera body so that it can be pressed against the camera body. When the FB correction lever is tilted to the left or right one time, the flange back moves by a small unit step and continues in the same direction. When the tilting operation is repeatedly performed, the fine unit step is moved in the same direction by the minute unit steps, and when the tilting operation state is maintained, the moving is continuously performed in the same direction. When the operation is performed, the flange back is configured to be movable in the opposite direction in the same manner as when the operation is performed to the one side. That is, the present invention
Based on a conventional lens mount that can be mounted and replaced with a lens mount, a drive power supply and drive mechanism, a fixed front part of the main body mainly including a camera holding grip with a release button, a distance measuring mechanism including a distance measuring element, film exposure A system different from the general one, which consists of a mechanism and a finder, etc., with the rear movable side, and focus adjustment is performed by adjusting the amount of movement of the rear movable side, and by automating this, AF photography can be done with the conventional lens Provides an AF single-lens reflex camera, and realizes a correction mechanism capable of arbitrarily correcting the focus according to the photographer's intention by a lever system which is extremely easy to operate in focusing by back focus.

[0006]

According to the above arrangement, as a shooting operation with the camera held, first, the AF operation is started by half-pressing the release button, and the distance information of the subject incident on the AF sensor located substantially at the center of the finder screen is obtained. The rear movable side where the focal plane of the camera body is located moves to a focusing position at a different distance depending on the mounted photographing lens. When the camera determines that the focal point has been reached, the movement of the main body rear movable side stops. Since the photographer can confirm the in-focus state on the finder screen, if the in-focus state is satisfactory, the photographer may press the release button further to shift to the photographing operation. However, if the user is not satisfied with the in-focus state or intentionally shifts the focus position with the intention of the photographer, an external operation unit (FB correction lever) is required on condition that the AF operation of the camera is completed. If −) is tilted in the direction to be corrected, the focal plane on the rear movable side of the main body moves in minute units (for example, 10 μm). If the operation by the external operation unit is repeated in the same direction, the focal plane moves by adding small units.

If the FB correction lever is operated in the opposite direction, the FB correction lever can be moved in the opposite direction. Therefore, the photographer can arbitrarily correct the FB image while taking into account the composition of the finder screen and the best image point. Image can be created.
Since this focus correction is a correction for the AF operation, A
The condition is that focusing by the F operation has been completed. A
If the FB correction lever is operated before the F operation is completed, it is not accepted. However, depending on the photographer, there is a case where the photographer wants to manually adjust the flange back to perform a satisfactory focus adjustment. Therefore, when the MF changeover switch is turned on, the MF photographing mode is set and the MF photographing mode is set. Under such a condition, the flange back can be arbitrarily moved by the above operation using the FB correction lever. The movement of the flange back by the FB correction lever is performed by repeating the operation of the FB correction lever in small unit steps, but the state in which the FB correction lever is kept tilted is maintained for a certain period of time (for example, one second). When you hold,
Move continuously and continue until the lever is restored.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a camera for explaining an embodiment of a focus correction mechanism of an AF single-lens reflex camera according to the present invention.
Indicates a state in which the focus is adjusted to the closest focus position. The camera body front block A includes an interchangeable lens 9,
The lens mount 1 includes an AF drive mechanism 7 and a grip 17 having a release button 14 (the release button and the grip are shown in FIG. 3). The rear block B of the camera body includes an up-down mirror 13, a finder mechanism 5, an aperture 10, an exposure mechanism, a film feeding mechanism, and a distance measuring mechanism 3. Light from a subject (not shown) passes through the interchangeable lens 9, the optical path is bent upward by 90 degrees by the up-down mirror 13, enters the finder mechanism 5, and becomes parallel to the main optical axis by the pentaprism 5 a. It is bent and reaches the eyepiece 5b. Part of the subject light that has passed through the interchangeable lens 9 also enters the AF mirror 3a of the distance measuring mechanism 3, the optical path is bent downward, and reaches the AF sensor 3c via the AF lens 3b.

The AF drive mechanism 7 includes a flange back drive motor 7a, an encoder 6 for detecting the number of rotations of the motor 7a,
Gears 7b, 7c, lead screw 7d and female screw 7
e. Flange back drive motor 7a
Is transmitted to the lead screw 7d through the gears 7b and 7c at a reduced speed. The lead screw 7d is screwed into a female screw 7e provided at the base of the rear block B of the camera body, and the rotation of the lead screw 7d changes the distance in the optical axis direction between the front block A and the rear block B of the camera body. I do. Thereby, the distance between the lens mount 1 and the aperture (opening) 10, that is, the flange back can be adjusted.

Information indicating the positional relationship between the front block A and the rear block B of the camera body can be detected by a position detection switch 8 which is a movable position detection means. The code pattern substrate 8a constituting the position detection switch 8 is fixed to the base of the front block A of the camera body, and its contact 8b
Are fixed to the base of the camera body rear block B, respectively. When the distance between the front and rear blocks A and B changes, the code pattern changes accordingly, and an FB position detection signal can be obtained. In addition, other methods such as sliding resistance may be used as the position detection switch 8 in addition to the code pattern. Camera body front block A and rear block B
The members connecting between the two blocks are provided with rails on the front block A and rollers on the rear block (both rails and rollers are not shown). Can be changed smoothly so that a load is not applied as much as possible. Note that a linearly moving bearing or the like may be used as the other connecting member.

A guide rod (not shown) is provided on the front block A of the camera body opposite to the lead screw 7d with the up-down mirror 13 interposed therebetween. A guide hole (not shown) is provided in the rear block B of the camera body as a member for guiding this. The guide rod slides in the guide hole with the rotation of the lead screw 7d.
The camera body rear block B is guided to the camera body front block A in cooperation with d. Thereby, the optical axis can be moved so that the optical axis between the two blocks does not shift, and the aperture surface and the lens mount surface are kept parallel.

FIG. 2 is a circuit block diagram showing an embodiment of the control circuit section in the present invention. Code pattern board 8a
, A flange back (hereinafter referred to as “FB”) position detection signal, an encoder signal from the encoder 6, and a distance measurement signal (AF information) from the AF sensor 3c. When the MF switch button 25 is pressed down, the switch 28 outputs an MF switch signal. Further, by operating the FB correction lever 30 which can be tilted left and right, forward and backward signals are output from the switches 31 and 32, respectively. Each of the above signals is input to the AF control circuit 20. When the release button 14 is half-pressed, the first switch 23 is turned on, an AF operation start signal is sent to the AF control circuit 20, and an AF check is performed. When the release button 14 is further depressed, the second switch 24 in the next stage is pressed.
Is turned on and the camera operation start signal is
, The mirror-up and shutter mechanisms are activated to take a picture, and then operations such as mirror-down and film winding are performed to complete the camera picture-taking operation.

FIG. 3 is a top partial perspective view of the camera showing an example of the arrangement of the FB correction lever, the MF switching button, and the release button in consideration of operability. A release button 14 is disposed above the grip 17, so that when the grip is gripped by the right hand, the index finger is naturally placed at the position of the release button 14 and the thumb has a shape such that it hits the position behind the camera body. The back 31a of the upper cover 31 of the camera
Is provided with an MF switching button 25, and an FB correction lever 30 is provided near the rear surface of the upper surface 31b. The abdomen of the thumb can be applied to the distal end portion 30a of the FB correction lever 30 and can be tilted right and left. When the FB correction lever 30 is tilted to the left or right, a biasing force is provided so as to return to the intermediate position. Therefore, when the thumb is released from the FB correction lever 30 by tilting the FB correction lever 30 to the left or right side, the FB correction lever 30 returns to the original intermediate position by the urging force.

FIG. 4 is a diagram for explaining front focus correction and rear focus correction of focus correction. (A) shows a state in which the flange back is brought to a focus position (focus position) by, for example, an AF operation. In this state, the state in which the flange back is slightly moved to a side shorter than the focus position is (b).
This is front focus correction as shown in FIG. On the contrary, the state where the flange back is slightly moved to the side longer than the focus position is (c).
As shown in FIG. In this way, the front focus and the rear focus can be corrected in accordance with the composition and the photographing situation.

FIGS. 5 and 6 are flowcharts for explaining the focus correction operation of the present invention. FIG. 5 shows the focus correction operation in the AF shooting mode, and FIG. 6 shows the flange back manual adjustment operation in the MF shooting mode. It is a figure for explaining. First, the focus correction operation in the AF photographing mode will be described. In FIG. 5, when the power switch is turned on and the power is turned on (S501), all the circuits are activated and the AF control circuit 2 is turned on.
Numeral 0 takes in a flange back position detection signal and displays the current flange back position on a display unit (not shown).
Thereby, the FB position can be confirmed (S50).
2).

A distance measurement operation is performed using the AF sensor signal (S503), and a defocus amount is calculated (S504).
Here, it is determined whether the release button 14 is half-pressed and the check switch 23 is turned on. That is, A
It is determined whether the F operation start signal has been sent to the AF control circuit 20 (S505). If the release button 14 has not been half-pressed, the flow returns to S503. When the release button 14 is half-pressed, the operation shifts to a focusing operation. That is, it is determined whether or not the camera is in focus (S506). If the camera is not in focus, the FB drive motor drive circuit 21 is controlled to move toward the focus according to the calculation result of the shift amount. (S507). This operation is repeatedly performed until a focus determination is made.

If the in-focus determination is Yes, the process enters a stage where the intention of the photographer is intervened for the first time (S508).
If the photographer determines that there is no need to make corrections while looking at the in-focus state of the AF, then the photographer will further depress the release button 14 (S509). As a result, the switch 24 is turned on and the camera operation start signal is output from the camera operation CPU 2
2 and a shutter operation is performed (S510). On the other hand, when it is determined that the correction is to be performed, the front focus side or the rear focus side is determined (S511). For example, if the front focus side as shown in FIG. (Refer to FIG. 3, right side) (S512). With this single operation, the focus surface moves forward (toward the lens) by the minute unit Δf of the flange back (S513). This operation is repeated until the photographer satisfies the correction state, for example, N times, and the front focus correction of + nΔF shown in FIG. When the correction is no longer necessary, the release button 14 is further depressed, and the shooting operation of the camera is started (S508, S509, S510). In addition,
When correcting to the rear focus side, the FB correction lever 30 is tilted to the N side (left side, see FIG. 3), the focus surface is moved backward by Δf, and, for example, when it is repeated N times, −n shown in FIG.
Post-focus correction of ΔF is performed (S514, S515).

Next, the manual operation for manually adjusting the flange back in the MF photographing mode will be described. In FIG. 6, the photographer decides whether to photograph in the AF mode or the MF mode in the camera in the photographing preparation state. The process starts (S601). The photographer checks whether the camera is in the AF shooting mode. As described above, the display unit (not shown) displays AF or MF, and the current mode is confirmed by this display (S602). If the camera is in the MF shooting mode, it is next determined whether to cancel the MF mode (S60).
3). Since MF shooting is desired, MF mode release is determined as No. Therefore, the camera uses M in S611.
The state set in the F photographing mode is maintained.

If the MF photographing mode is entered before the AF focusing mode is set and the AF focusing is performed, the following steps are taken. If the AF shooting mode has been set in S602, the operation proceeds to the release check operation. If the release check operation has been performed (S605), the process proceeds to a determination as to whether or not the AF operation has been performed (S605). S60
6). On the other hand, if the MF photographing mode is set in the step S602, the MF photographing mode is canceled in the next step S603, and the MF switching button 25 is pressed (S604), and the above-described release check operation is performed. Move to Even during the AF operation after the release check operation is performed, the operation of the FB drive motor drive circuit 21 is stopped by depressing the MF switching button 25 (S609, S609).
610), the camera is set to the MF shooting mode in S611. By operating the FB correction lever 30 in this state, the front and rear correction movements of the flange back can be arbitrarily performed (S614 to S617).

Incidentally, initially in the AF shooting mode state,
When the photographing is to be performed by the AF as it is, the processing in S50 of FIG.
As in steps S510 to S510, the release button 14 is half-pressed to turn on the check SW, the AF operation is started to focus, and then the release button 14 is further depressed to perform the shutter operation (S607, S608, S612). ,
S613). 5 and 6, one of the FB correction levers is shown.
The case of moving by the minute unit Δf by the rotation operation has been described, but if the state where the FB correction lever is tilted is held for a certain time (T), the movement can be continuously performed from that point. FIG. 7 is a flowchart showing the operation when the FB correction lever is held as described above. When the FB correction lever 30 is tilted to the F side or the N side (S701, S70
5), the AF control circuit 20 activates a built-in timer and measures elapsed time (S702, S706). When the timer elapses the time T or more, the flange back is continuously advanced or continuously retracted (S704, S708). In the above embodiment, the case where the FB correction lever is disposed at the rear portion of the upper surface of the camera body has been described. However, the FB correction lever may be disposed at the rear portion of the camera body.

[0021]

As described above, according to the present invention, in the AF single-lens reflex camera of the back focus control system, the focusing operation is started in the AF photographing mode by half-pressing the release button, and the focusing operation is performed by the flange back adjustment. Later, or even during the AF operation, the MF changeover switch is used to set the MF shooting mode.
The flange back which is switched to the focus position or stopped at the focal point or at an arbitrary position can be moved forward and backward by a small distance unit stepwise by an external operation unit. In addition, the external operation unit is positioned at a position where it can be freely operated left and right with the abdomen of the thumb that hits the back of the camera by holding the grip.
It is configured by providing a B correction lever. Therefore, the focusing is performed by the AF operation which is faster than the manual operation, and the MF is performed after the focusing operation or during the AF operation.
By switching to the MF photographing mode by the changeover switch, the focus state of the flange back can be promptly corrected to the state intended by the photographer.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a camera for explaining an embodiment of a focus correction mechanism of an AF single-lens reflex camera according to the present invention, where (a) is a focus position for infinity shooting, and (b) is the closest shooting. Are respectively adjusted to the in-focus position.

FIG. 2 is a circuit diagram showing an embodiment of a control circuit portion of FIG.

FIG. 3 is a partial perspective view showing an embodiment of the appearance near the upper part of the grip of the camera.

FIG. 4 is a diagram for explaining front focus correction and rear focus correction of focus correction.

FIG. 5 is a flowchart for explaining a focus correction operation in an AF photographing mode.

FIG. 6 is a flowchart for explaining the operation of manual FB adjustment when switching to the MF photographing mode.

FIG. 7 is a flowchart for explaining the operation when the FB correction lever is held for a predetermined time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens mount 2 Film surface 3 Distance measuring mechanism 5 Viewfinder mechanism 6 Encoder 7 AF drive mechanism 8 Position detection switch 9 Interchangeable lens 10 Aperture 11 Pressure plate 13 Up / down mirror 14 Release button 17 Grip 20 AF control circuit 21 FB drive motor drive circuit 22 Camera operation CPU 23, 24, 28, 31, 32 Switch 25 MF switch button 29 Drive circuit 30 FB correction lever

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshinori Koshimizu 2-14-9 Tamagawadai, Setagaya-ku, Tokyo Kyocera Corporation Tokyo Yoga Office (72) Inventor Nobuo Kitamura 2--14 Tamagawadai, Setagaya-ku, Tokyo No. 9 Kyocera Corporation Tokyo Yoga Office (72) Inventor Tadaaki Ishikawa 2-14-9 Tamagawadai, Setagaya-ku, Tokyo Kyocera Corporation Tokyo Yoga Office (72) Inventor Shin Yasuhara 2 Tamagawadai, Setagaya-ku, Tokyo No. 14-9, Kyocera Corporation Tokyo Yoga Office (56) References JP-A-5-173225 (JP, A) JP-A-5-48957 (JP, A)

Claims (3)

(57) [Claims] 1. A camera body front block including at least a photographing lens and a lens mount for the photographing lens, a camera body rear block including at least a film opening, a camera body front block, and the camera body rear block. The front and rear blocks are connected so that the distance can be adjusted, and an AF drive mechanism that adjusts the distance between the lens mount of the front block of the camera body and the opening of the rear block based on AF information. An autofocus single-lens reflex camera configured to focus by adjusting the flange back of the photographing lens, wherein a release button is pressed halfway in an AF photographing mode. when, and when to start the focusing operation, it reaches a focal point by the flange back adjustment, the flange back Forward or backward in the vicinity of the focus point by the external operation unit
The unit can be moved to a small unit Δ by one operation of the external operation unit.
Move the focus plane forward or backward by f
When the external operation unit is operated N times, -nΔf or + n
A focus correction mechanism for an autofocus single-lens reflex camera, wherein a focus plane is corrected by Δf . 2. The apparatus according to claim 1, wherein the MF photographing mode is switched to the MF photographing mode during the AF focusing operation, and the flange back position can be arbitrarily moved by the external operation section. The focus correction mechanism for an autofocus single-lens reflex camera according to claim 1. 3. The external operation unit is an FB correction lever that can swing left and right with one end as an axis, a grip for operating a release button with a forefinger, and a thumb positioned on the back of the camera body. In this state, the thumb is placed on the top or back of the camera body so that the abdomen of the thumb can be pressed against the other end. When the FB correction lever is tilted once to one of the left and right sides, the flange back is When moving by a minute unit step and successively performing the tilting operation repeatedly in the same direction, moving by the minute unit step in the same direction and continuously moving in the same direction when the tilting operation state is maintained. When the FB correction lever is tilted in the opposite direction, the flange back can be moved in the reverse direction in the same manner as when the FB correction lever is tilted to the one side. Claim 1
Or a focus correction mechanism of the autofocus single-lens reflex camera described in 2.