JP4271761B2 - Lens barrel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens barrel of an interchangeable lens of a system camera, particularly a single lens reflex camera, and more particularly to a lens barrel of an AF single lens reflex camera capable of manual distance ring adjustment.
[0002]
[Prior art]
In AF single-lens reflex cameras, a manual clutch mechanism is installed in the manual distance adjustment mechanism of the inter-body motor type and in-lens motor type AF dedicated interchangeable lens, and the drive motor interlocking system (AF operation mode) and manual interlocking system (MF operation mode) ) Is generally switched. However, with the method of switching by a mechanical mechanism, the degree of freedom in design is necessary, considering the need for the switch to be placed near the mechanism, the switch moving distance and power depending on the mechanism, and the effects of touch and other factors. Will be limited. Therefore, as seen in Japanese Patent No. 2770787, a method of automating the switching between the AF operation mode and the MF operation mode using an electric element such as an electromagnetic clutch is considered.
[0003]
[Problems to be solved by the invention]
However, in this method, in addition to the state detection switch for confirming whether it is the AF operation mode or the MF operation mode, a target detection switch for setting the AF operation mode or the MF operation mode must be used. This increases the cost of electrical equipment and the like, and complicates the structure. Therefore, there has been a demand for a lens barrel having a simple clutch mechanism having a structure using an electric element while taking advantage of the AF and MF operation modes.
[0004]
[Means for Solving the Problems]
In order to solve such a problem, the present invention performs pre-shooting preparatory operations such as ranging, automatic focusing, and photometry by half-pressing the shutter button of the camera in the automatic focusing drive operation mode (AF operation mode). As a lens barrel that is connected to a camera that releases the shutter by further pressing the shutter button, a general barrel having a distance adjustment barrel that is driven from the main motor for driving the lens through a speed reduction mechanism and a manual adjustment barrel that is interlocked with the distance barrel The drive connection mechanism from the main motor to the distance adjustment cylinder is always parted except when the main motor is driven, and the drive connection mechanism is completed immediately before the main motor is operated. A clutch mechanism by a dedicated motor (hereinafter referred to as a clutch motor) and a control program thereof are assembled so as to be shut off, and the control program is a shutter. When half-pressed state of being released, tried to overcome by even while the control sequence will be configured to manually focusing operation returns to ready.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The clutch mechanism, which is the main part of the configuration, is operated by a clutch motor, and the power transmission system on the main motor side and the distance adjustment cylinder side is shut off when normal autofocus adjustment is inoperative, and the distance adjustment cylinder can be manually adjusted arbitrarily. In the autofocus operation, before the rotational power of the main motor is obtained, an operating current is supplied to the clutch motor, the clutch is engaged, and the main motor power can be transmitted to the distance adjusting cylinder. Further, when the main motor stops rotating, current is sent again to the clutch motor, the clutch is disengaged, and the transmission system between the main motor and the distance adjusting cylinder is shut off.
[0006]
【Example】
Hereinafter, the best embodiment of the present invention will be described with reference to the drawings.
[0007]
FIG. 1 is a schematic perspective view of a clutch mechanism employed in the lens barrel of the present invention, and FIG. 2 is an operation circuit diagram thereof. FIG. 3 is a clutch operation diagram by the clutch motor, and FIG. 4 is a flow chart of logical operation. When the shutter button of the camera is half-pressed, pre-shooting preparatory operations such as distance measurement, automatic focusing and photometry are performed. The operation when the lens barrel of the present invention is connected to a camera that releases a shutter by pressing a button is shown. FIG. 5 is a cross-sectional view of a lens barrel in which the clutch mechanism of the present invention is mounted, and shows an embodiment of an in-lens motor type. In the drawings, the same members are denoted by the same reference numerals.
[0008]
In the lens barrel cross-sectional view of FIG. 5, there are a front lens unit L1 and a rear lens unit L2 around the optical axis L0, and focus adjustment is performed by moving the front lens unit L1 straight with respect to the rear lens unit L2. An example of a possible lens barrel is shown.
[0009]
The front lens group L1 is held by the holding frame 1, the rear lens group L2 is held by the front holding frame 2, and the helicoid part 5a of the distance adjusting cylinder 5 and the moving cylinder to which the holding frame 1 of the lens group L1 is fixed. The four helicoid portions 4a are engaged with each other, and the movable cylinder 4 and the distance adjusting cylinder 5 can move linearly and integrally with the fixed cylinder 3. Further, the manual adjustment cylinder 6 is provided on the distance adjustment cylinder 5, and the key 5b of the distance adjustment cylinder 5 is fitted in the inner straight keyway 6a, so that the rotation of the manual adjustment cylinder 6 can be transmitted to the distance adjustment cylinder 5. In addition, due to the change in the relative angle between the movable cylinder 4 and the distance adjusting cylinder 5, the linear movement positions of the distance adjusting cylinder 5 and the front lens unit L1 of the holding frame 1 with respect to the movable cylinder 4 change, so that the focus adjustment of the main barrel can be performed. It is possible.
[0010]
On the other hand, the power from the lens driving motor 12 is supplied from the pinion 12a of the motor shaft through the reduction gear trains 11a, 11b and the clutch mechanism 10 through the reduction gear trains 9a, 9b, 9c, 9e. The internal gear 6b formed on the side is rotated to enable automatic focusing drive.
[0011]
Next, the structure and operation of the clutch mechanism 10 will be described.
[0012]
In FIG. 1, a clutch gear 13 for intermittently driving the lens drive motor 12 is a step gear, and is composed of gears 13a and 13b. The clutch gear 13 is movable while being restricted in the axial direction in the axial direction, and is rotatably fitted to the shaft 14. A spring receiver 20, a spring 19, and a clutch gear 13 are inserted in this order on the shaft 14 fixed to the U-shaped member 18. The spring 19 presses the clutch gear 13 upward in the figure, and when the shaft 14 moves upward in the figure as will be described later, the teeth of the interlocking gear 9a and the gear 13b come into contact with each other. Even when it cannot move in the axial direction, the pressing force is constantly applied from the spring 19 in the axial direction, so that automatic focusing drive is performed, and the gear 13b rotates, so that the gears are not caught and the clutch gear 13 is engaged with the interlocking gear. Move to the 9a side. Note that the holding torque of the lens driving motor 12 including the reduction gear train has a sufficient holding torque that does not move even when force is applied from the clutch shaft side.
[0013]
The shaft 14 is supported by an unillustrated shaft support member so as to be movable in the axial direction. Further, an eccentric roller 17 is inserted into the U-shaped member 18 to rotate the clutch motor 15 through the reduction gear trains 15a and 16. A shaft 16a connecting the reduction gear trains 15a, 16 and the eccentric roller 17 is supported by a non-movable shaft supporting member (not shown). Further, a protrusion 18c extends from the U-shaped member 18, and is engaged with the position detection switch S1 or S2 in accordance with the clutch operation.
[0014]
FIG. 3 explains the operation of the clutch mechanism. FIG. 3A shows the MF operation mode. At this time, the interlocking between the gear 13b and the interlocking gear 9b is released. When the protrusion 18c touches the position detection switch S2, the position detection switch S2 is energized and gives position information. At this time, the position detection switch S1 is in a state where no current flows.
[0015]
Next, when the clutch motor 15 rotates, since the position of the shaft of the eccentric roller 17 is fixed with respect to the paper surface, the eccentric roller 17 rotates so as to push up the member 18a, and the gear 13b and the interlocking gear 9b are moved. Interlocked. When the protrusion 18c touches the position detection switch S1 and the position detection switch S1 is ON, it indicates that the clutch mechanism 10 is in a connected state (FIG. 3B), and again when the eccentric roller 17 rotates. The eccentric roller 17 pushes down the member 18b, the position detection switch S2 is turned on, and the clutch mechanism 10 is in a disconnected state (FIG. 3A).
[0016]
FIG. 2 is an operation circuit of an electric element used in the clutch mechanism. A lens barrel connected to a camera (not shown) transmits and receives information from the camera CPU 21 and information from the lens CPU 22 in the camera via the mount unit. The lens CPU 22 determines the signals obtained from the position detection switches S1 and S2, and sends control signals to the drive circuits 23 and 24 to drive and stop the lens drive motor 12 and the clutch motor 15, respectively. .
[0017]
FIG. 4 shows the logical operation of the electrical element. Hereinafter, the control sequence will be described with reference to FIG.
[0018]
When the camera is set in the AF operation mode, as described above, manual operation is possible before the release (MF operation mode). Here, when a pre-shooting preparation state such as distance measurement or photometry is entered by half-pressing the shutter button of the camera, the control sequence in the AF operation mode is started (30). The lens CPU 22 confirms the conduction state of the position detection switch S2 (31) and drives the clutch motor 15 (32). At this time, if the conduction state of the position detection switch S2 is confirmed, the process proceeds to the confirmation of the position detection switch S1 (33). If the conduction is not confirmed, the position detection switch S1 is confirmed until confirmation. (34). The confirmation process of the position detection switch S2 may or may not be performed. Next, the clutch motor 15 is driven until the conduction of the position detection switch S1 is confirmed (32). If it is confirmed, the clutch engagement operation is completed (35), the rotation of the clutch motor 15 is stopped (36), and it is confirmed whether or not the shutter button is half-pressed (37). When it is confirmed that the shutter release state is not half-pressed, the lens motor is not driven (40), the clutch motor 15 is rotated (41), the clutch mechanism 10 is disengaged (43), and the MF operation mode is entered. Return. When the half-press release state is confirmed (37), the lens driving motor 12 is driven (38), and an in-focus determination is performed (39) (AF operation mode). If the in-focus state is not confirmed, the process returns to the release state confirmation again. When the in-focus state is confirmed, the lens driving motor 12 is stopped (40), the clutch motor 15 is rotated (41), and when the position detection switch S2 detects the position (42), the clutch mechanism 10 is completely disconnected, Transition to MF operation mode. That is, the clutch motor 15 rotates and the interlocking of the clutch gear 13 and the interlocking gear 9a is released. When the shift to the MF operation mode is detected by the position detection switch S2, it is determined that the clutch mechanism 10 has completed the disengagement operation (43), and the rotation of the clutch motor 15 is stopped (44). This completes one operation (45).
[0019]
As described above, normally, the clutch gear 13 and the interlocking gear 9a inside the clutch mechanism 10 are in the non-interlocking state and are in a state where manual operation is possible. Only when the automatic focusing drive is performed, the clutch gear 13 and the interlocking gear 9a are interlocked to perform the automatic focusing drive. Upon completion of the focusing, the interlocking of the clutch gear 13 and the interlocking gear 9a is released again, and the manual operation is performed. It becomes possible.
[0020]
Note that the operation of pressing the shutter button further from the half-pressed state of the shutter button is the so-called single mode in which the AF operation mode on the camera side does not release the shutter unless it is in focus, or the shutter is released whenever the shutter button is pressed. It goes without saying that it depends on whether it is a continuous mode or a combination thereof.
[0021]
【The invention's effect】
As described above, according to the configuration of the present invention, the AF operation mode and the MF operation mode can be photographed without switching between the AF operation mode and the MF operation mode, that is, the AF operation mode, that is, the AF operation is performed. It is possible to automatically switch between the AF operation mode and the MF operation mode by using the electric motor while eliminating the need for the target detection switch for the mode and the MF operation mode.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a clutch mechanism according to an embodiment.
FIG. 2 is an operation circuit diagram of the clutch mechanism of the embodiment.
FIG. 3 is an operation explanatory diagram of the clutch mechanism of the embodiment.
FIG. 4 is a logical operation flowchart of the clutch mechanism of the embodiment.
FIG. 5 is a cross-sectional view of a lens barrel of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Holding frame 2 Holding frame 3 Fixed cylinder 4 Moving cylinder 5 Distance adjusting cylinder 6 Manual adjusting cylinder 9a Interlocking gear 10 Clutch mechanism 12 Lens drive motor 13 Clutch gear 14 Shaft 15 Clutch motor 16a Shaft 17 Eccentric roller 18 U-shaped member 19 Spring 20 Spring receiver 21 Camera CPU
22 Lens CPU
23 drive circuit 24 drive circuit S1 position detection switch S2 position detection switch

Claims (1)

A motor for driving the distance adjusting cylinder or a manual driving force can be switched without a changeover switch, and the driving force from the motor to the distance adjusting cylinder is transmitted via the clutch mechanism, and the coupling of the clutch mechanism and its In the lens barrel that is released by the vertical movement of the clutch shaft provided on the U-shaped member into which the eccentric roller rotated by the dedicated small motor is inserted,
Normally, the clutch mechanism is disengaged, the transmission of driving force from the motor to the distance adjusting cylinder is cut off, and manual focus adjustment is always possible,
When the shutter button is half-pressed, the clutch mechanism is connected, and a driving force is transmitted from the motor to the distance adjusting cylinder, so that automatic focus adjustment is possible.
When the automatic focus adjustment operation is completed, the driving of the motor is stopped, the clutch mechanism is disengaged, and the normal focus adjustment is always restored to the normal state.
If the half-press of the shutter button is released even if the automatic focus adjustment operation is not completed, the drive of the motor is stopped, the clutch mechanism is disengaged, and manual focus adjustment is always possible at normal times. A lens barrel that returns to a state.

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