JPH0210488Y2 - - Google Patents

Description

[Detailed description of the invention] This invention has a lens drive motor and a focus detection sensor built into the camera body, and the focus of normal lenses is adjusted by the motor, especially for telephoto lenses that require a large driving force. The present invention relates to an automatic focus adjustment device in which a motor is built into the lens, data regarding the amount of lens drive is sent from the camera body, and the motor on the lens side adjusts the focus automatically.

2. Description of the Related Art A focus detection sensor is known in which light transmitted through an objective lens is received by a focus detection sensor, and the distance from the focal point of the lens can be determined.

By driving the objective lens of the lens based on the detection data of the sensor, an automatic focusing camera can be realized.

When converting a single-lens reflex camera with interchangeable lenses to an autofocus camera, driving a large lens with a long focal length, such as a telephoto lens, becomes a problem.

In other words, a relatively large capacity power source and a large output motor are required to drive the lens.
If such a power source and motor are provided on the camera body side, the camera body will become large.

The purpose of the present invention is to incorporate a relatively small lens drive motor and a focus detection sensor into the camera body, and use the motor to adjust the focus of a normal lens.
In particular, lenses that require a large driving force, such as telephoto lenses, have a built-in motor on the lens side, send data about the amount of lens driving from the camera body, and use an automatic focus adjustment device that automatically adjusts the focus using the motor on the lens side. It is about providing.

In order to achieve the above object, an automatic focus adjustment device according to the present invention that drives a lens with a motor on the lens side is an automatic focus adjustment device that drives a lens with a motor on the lens side of a lens interchangeable camera. a sensor, a coupler that transmits rotation to the lens side by a lens drive amount based on detection data of the sensor; a lens drive mechanism and a motor on the lens side; a first rotating body that is coupled to the coupler and rotates; a second rotating body disposed facing the first rotating body and rotated in response to focus adjustment of the lens; a transmission-type photoelectric sensor for detecting a phase shift between the first rotating body and the second rotating body; a detector, and a motor drive circuit that drives the motor in a direction that reduces the phase shift between the rotating bodies according to the output of the transmission type photoelectric detector, and The lens is configured to drive the lens by a corresponding amount.

According to the above configuration, since it is sufficient to transmit from the camera body a rotation amount corresponding to the necessary movement amount of the lens (there is no need to transmit a force for driving the lens), the motor on the camera body side can be small.

Hereinafter, the present invention will be explained in more detail with reference to the drawings and the like.

Figure 1 shows the first automatic focus adjustment device according to the present invention.
FIG. 2 is a block diagram showing an embodiment of the invention.

The structure on the camera body side and the structure on the lens side are shown separated by broken lines.

The light that enters from the object through the objective lens is
The light passes through the main mirror 31, is reflected by the auxiliary mirror 32, and enters the focus detection sensor 33.

The output of this focus detection sensor 33 is input to a CPU (lens side) 36 via an interface circuit 35, and the amount of movement N and direction DR required to bring the objective lens to the focal position are calculated.

The motor drive circuit 38 is connected to the CPU (lens side) 3
Motor 1 is driven by a signal from 6.

The rotation of the motor 1 is caused by the output gear 2, the transmission gear 3,
4 to the clutch gear 5.

The rotation of the motor 1 is used for both automatic focus adjustment and winding of a shutter, film, etc. by moving the clutch gear 5 with an electromagnetic clutch 6. Figure 1 shows the rotation of motor 1 as
It shows a state where it is connected to a winding film or the like.

Clutch position detection switches 10 and 11 are switches for detecting the position of the clutch gear 5.

During automatic focus adjustment, the clutch gear 5 is moved downward in the figure by an electromagnetic clutch 6, and the motor 1
The rotation is transmitted via the lens drive gear train 12 to 20 to the coupler shaft 23 facing the mounting surface of the camera body. This camera body is intended not only for a lens incorporating a motor 47, which will be described later, but also for a lens capable of automatic focus adjustment, in which the lens is driven by the rotation of the coupler shaft 23.

First, the configuration of the camera body will be further explained assuming that such a lens is attached.

The rotation of the coupler shaft 23, that is, the driving amount of the lens is:
It is constantly measured by the encoder on the camera body side. Rotation of gear 20 (rotation of coupler shaft 23) is transmitted to encoder disk 28 via gear 21. This disk 28 is provided with a large number of holes concentrically, and an encoder LED 29 and an encoder phototransistor 27 are arranged to detect the number of holes passed through. The encoder output pulses taken out from the phototransistor 27 are passed through the interface circuit 35.
When a movement corresponding to the movement amount N is input to the CPU 36 and measured before rotating the motor 1,
The CPU 36 causes the motor drive circuit 38 to stop driving the motor 1 . The CPU 36 reads the data from the focus detection sensor 33 again and confirms the lens drive result.

The automatic focus adjustment device of the present invention is realized by attaching the lens described below (hereinafter simply referred to as a long focus lens) to the camera body as described above.

A mount portion of a long focal length lens is provided with a grounded terminal that indicates that the lens is a long focal length lens when it is attached to a camera body.

When a long focal length lens is attached to the camera, the lens identification signal pin 54 on the camera body side becomes a ground potential, and the CPU 36 on the camera body side receives information that a long focal length lens is attached.

A coupler 24 on the long focus lens side (hereinafter referred to as the lens side) is coupled to the coupler shaft 34 when this lens is attached to the camera body.

The rotation of the coupler shaft 24 is connected to a disc 44 (first rotating body) of the photointerrupter via a gear.

When the coupler shaft 24 rotates, the disk 44 also rotates. On the long focus lens side, there is a unique motor 47 for driving the lens, a battery 51 that drives this motor,
A power supply circuit 50 is provided that boosts and rectifies the battery output and supplies power to the CPU 49.

The CPU 49 controls the motor drive circuit 52 to drive the lens 30. The rotation of the motor 47 is caused by the gear 4
6 etc. to the helicoid 53 and the lens 3
Advance or retreat 0. The shaft for driving the helicoid 53 includes a photointerrupter disk 43 that rotates facing the photointerrupter disk 44 described above.
(second rotating body) is provided.

In order to illuminate the disk 44 of the photointerrupter as uniformly as possible, a plurality of LEDs 41 are fixedly provided on the barrel side of the lens and turned on when necessary. LED
A driver 53 controls lighting of the LED 41 based on a signal from the CPU 49. The shapes of the photointerrupter discs 43 and 44 are shown in FIG. 2, and the relationship between the photointerrupter disc 43 and three phototransistors 40-1 to 40-3 is shown in an enlarged manner in FIG.

As shown in FIG. 2A, the photointerrupter disc 44 is coded in the circumferential direction by radial codes, and the home position is the 0 position written on the outer periphery, from the lens side to the camera body. The clockwise direction of rotation when looking at is indicated by CW, and the counterclockwise direction of rotation is indicated by CCW. As shown in FIG. 2B, the photo-interrupter disc 43 is provided with three holes radially extending from its outer periphery. Phototransistors 40-1 to 40-3 are provided corresponding to the holes in the disc 43 of the photointerrupter and rotate together with the disc.

In order to take out the output signals of the phototransistors 40-1 to 40-3 from the disk 43 of the photointerrupter, annular contacts P ₁ , P ₂ , P ₃ and PGND are provided, and each contact has a sliding contact S ₁ , S ₂ , S ₃ and SGND
is being addressed. The output signals of the phototransistors 40-1 to 40-3 taken out via the sliding contacts S ₁ , S ₂ , S ₃ and SGND are amplified by preamplifiers 48-1 to 48-3, respectively, as shown in FIG. and input to the CPU 49. Vop ₁ for each output voltage of preamplifiers 48-1 to 48-3
~Vop ₃ . Phototransistor 40-
When the light from LED 41 hits 1, the preamplifier 48-
1 output signal Vop ₁ becomes High.

is installed on the camera body side, signal pin 5
4 is shorted to GND on the lens side, so the CPU on the camera side reads this signal and determines that a long focal length lens is attached.

This signal can also be used to control the CPU 36 of the camera body so that the torque of the coupler shaft is reduced and the rotation of the motor 1 is not increased.

The CPU 36 on the camera body side processes the output signal of the focus detection sensor 33 built into the camera side, and as a result, the number N of driving pulses to extend the lens 30.
and the direction DR, and drive the motor 1 on the camera side. The number of pulses is measured from the output signals of the photocouplers 27 and 29 of the encoder, and compared with the calculation results.
to stop. This operation is the same as described above.

While the motor 1 is rotating, the rotation of the coupler 23 is transmitted to the coupler 24 on the lens side, and the disc 44 of the photointerrupter is rotated.

The CPU 49 on the lens side reads the signals of the three phototransistors 40-1 to 40-3, performs logical operations, and determines the direction of rotation of the disk 43. That is, by driving the motor 47, the disc 44 and the disc 43 are constantly driven.
The motor 47 is rotated so that the disc 43 follows the rotation of the disc 44 so as to maintain a constant mechanical position (home position) with the disc 44.
This will be explained in more detail below.

FIG. 5 is a diagram showing a code indicating a state determined by the positional relationship between the discs 44 and 43 of the photointerrupter, and the contents of control of the CPU 49 corresponding to the code. The CPU 49 divides the positional relationship between the discs 44 and 43 of the photointerrupter into six stages, detects each state, and causes the motor 47 to perform control corresponding to each state. CPU36 currently built into the camera body
obtains data on the driving amount and direction of the lens by the focus detection sensor 33 inside the body, and when the motor 1 is driven, the coupler 24 on the lens side is rotated, and the disc 44 of the photointerrupter is moved from the front of the lens to the camera side. Suppose that when you look at the object, it is rotated in the CW direction. Since the photointerrupter disk 43 is initially stopped, the phototransistors 40-1 to 40
-3 is the number 0 → 1 shown on the outer periphery of the disk in Figure 2A
You will see patterns shown in the order of →3 to 7→8.

Now, if we look at pattern 8, the preamplifier output signals Vop ₁ , Vop ₂ , and Vop ₃ which amplified the outputs of the phototransistors 40-1 to 40-3 are the outputs of the state (001) shown in FIG. become. When the CPU 49 reads this (001) output signal, the CPU
49 drives the motor 47 to rapidly rotate the photointerrupter disc 43 in the CW direction. Naturally, the lens 30 is also driven at this time.

The photo-interrupter disc 43 follows the disc 44 in a direction approaching the home position indicated by number 0. When approaching the position where pattern number 3 is viewed, the outputs of Vop ₃ , Vop ₂ , and Vop ₁ become outputs (011) shown in State 2. When the CPU 49 receives this output signal, it reduces the rotational speed of the photointerrupter disc 43. This allows the pattern to slowly approach the home position.

If it matches the pattern of home position number 0, the outputs of Vop ₃ , Vop ₂ , and Vop ₁ will be (111).
When this state (State 3) is detected, the rotation of the motor 47 is controlled to continue this state. The long focus lens is attached to the contact point 54 on the mount surface.
If the CPU 36 on the camera side reads this as a Low signal, the CPU 36 controls the motor 1 so that the motor 1 moves at a constant speed except when the motor 1 is started or stopped. Therefore, since the rotation of the disk 44 is uniform, tracking and control of the disk 43 becomes easy.

Contrary to the above, the photointerrupter disk 44 advances in the CCW direction from the home position and Vop ₁ , Vop ₂ ,
Suppose that the output signal of Vop ₃ becomes, for example, the state of State 5 (100) caused by the pattern of number -5.

In this state, the CPU 49 drives the motor 47 so that the photointerrupter disk 43 rapidly rotates in the CCW direction.

As a result, the home position of the photointerrupter disk 43 is brought closer to the home position of the photointerrupter disk 44.

As described above, the home position of the photo-interrupter disk 43 is made to follow the home position of the photo-interrupter disk 44 in a servo manner, and when the photo-interrupter disk 44 stops, the photo-interrupter disk 43 moves to Vop ₁ , Vop ₂ and Vop ₃ are 111
It is rotated so that it becomes the output of (State 3), and finally it is stopped when it matches the home position. When Vop ₁ , Vop ₂ , and Vop ₃ are in the state of 000, the CPU 49 stores the previous detection state, so the program is written in advance to execute the previous state.

As described above, the lens 30 is moved and focused by accurately tracking the amount of rotation transmitted from the camera body side.

The result of this focus adjustment is evaluated by the focus detection sensor 33 and CPU 36 on the camera body side.

As described above, according to the present invention, when a rotation corresponding to the required amount of lens movement is transmitted from the camera body side to the lens side, the lens side automatically moves the lens by an amount corresponding to this amount of rotation. Automatic focus adjustment is possible.

A lens-side motor is driven in a direction that reduces the phase shift between the first and second rotating bodies in accordance with the output of a transmission type photoelectric detector that detects a phase shift between the first and second rotating bodies. A motor drive circuit is provided, and a feedback system is also formed on the lens side to ensure reliable operation.

[Brief explanation of the drawing]

Figure 1 shows the first automatic focus adjustment device according to the present invention.
FIG. 2 is a block diagram showing the implementation of the method. FIG. 2 is an enlarged plan view of the disk of the photointerrupter. FIG. 3 is an enlarged view of the disk of the photointerrupter on the signal extraction side. FIG. 4 is a connection diagram of phototransistors. FIG. 5 shows a code indicating a state determined by the positional relationship between discs 44 and 43 of the photointerrupter and its corresponding code.
FIG. 4 is a diagram showing the content of control by the CPU 49. 1... Motor (camera body side), 2... Output gear, 3, 4... Transmission gear, 5... Clutch gear, 6... Electromagnetic clutch, 7, 8... Shutter drive gear, 10, 11... Clutch position detection switch, 12-20... Lens drive gear train, 21, 2
2...Encoder drive gear, 23...Coupler shaft,
24... Coupler (lens side), 27... Encoder phototransistor, 28... Encoder disk, 29... Encoder LED, 30... Lens, 31... Main mirror, 32... Auxiliary mirror,
33...Focus detection sensor, 34...Coupler (coupler body side), 35...Interface circuit,
36... CPU (lens side), 37... Electromagnet drive circuit, 38... Motor drive circuit, 40... Phototransistor, 41... LED, 42... Reduction gear,
43, 44...Photo interrupter disk, 4
5...Helicoid, 46...Coupler shaft, 47...
Motor (lens side), 48...Preamplifier, 49
... CPU (lens side), 50 ... Power supply circuit, 51
...Battery (lens side), 52...Motor drive circuit,
53...LED driver, 54...lens identification signal pin, 60...potentiometer, 66...drive gear train.

Claims (1)

[Scope of utility model registration request] In an automatic focusing device that drives a lens with a motor on the lens side of a lens-interchangeable camera, a focus detection sensor is provided on the camera body side, and a coupler that transmits rotation to the lens side by a lens drive amount based on detection data of the sensor, A lens drive mechanism and a motor are provided on the lens side, and a first motor is connected to the coupler and rotates.
a rotating body, a second rotating body disposed facing the first rotating body and rotated in response to focus adjustment of the lens, and a phase shift between the first rotating body and the second rotating body; A transmission-type photoelectric detector for detecting the detection, a motor drive circuit for driving the motor in a direction in which a phase shift between the rotating bodies is reduced according to the output of the transmission-type photoelectric detector, and the camera body side An automatic focusing device that drives a lens with a motor on the lens side, characterized in that the lens is driven by an amount corresponding to the amount of rotation of a coupler.