JPH01261621A - Lens exchangeable camera system and exchangeable lens and lens driving mechanism used therefor - Google Patents

Abstract

PURPOSE:To enable an optical system to select an optimum focusing state by providing a front group lenses of one or more groups and an output means which can transmit the information peculiar to the front group lenses outputted from the output means to a camera main body on an exchangeable lens side. CONSTITUTION:Rear group lenses 13a and 13b containing a lens for inner focusing and a driving device for the lens for inner focusing are provided on a camera main body 1 side. Then front groups lenses 20 of one or more groups and an output means which can transmit the information peculiar to the front group lenses 20 outputted by the output means are provided on an exchangeable lens side. At the same time, control means 6 and 7 which perform control in accordance with the peculiar information outputted from the output means are provided on the camera main body 1 side. Therefore, photographing can be performed by selecting the exchangeable lens provided with a lens for front focusing and, when the exchangeable lens has a zooming function especially, focusing can be performed with the minimum variation in aberration.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an interchangeable lens camera system useful for 35 mm still cameras, video cameras, etc., and an interchangeable lens and lens drive mechanism used in the camera system.

[Conventional technology]

As a conventional interchangeable lens camera system, a variable magnification optical system was introduced in 1977, which is an optical system consisting of a front group lens and a rear group lens, and the magnification is changed by exchanging the front group lens.
41340, JP-A-61-129612, and other publications.

In addition, recent cameras have become increasingly automated, and features such as automatic exposure, automatic focus, power focus, power zoom, and automatic strobe illumination mechanisms have become commonplace.

As a result, the interface between the camera body and the interchangeable lens has become complicated, and as a result, most video cameras no longer have interchangeable lenses, and fixed zoom lenses have become mainstream. Fixed zoom lens types are also increasing in 35mm cameras.

(Problems to be Solved by the Invention) Conventional fixed zoom lenses have a problem in that there is a limit to the range of change in focal length, making it impossible to take pictures over a wide range as in a full-fledged interchangeable lens type camera.

The present invention does not require replacing the entire lens system as in the case of conventional interchangeable lenses for single-lens reflex cameras, but instead integrates the camera body and the rear group lens including the inner focus lens, and enables various lenses with various magnifications to be used. The camera system has an interchangeable front group lens, and when the front group lens is replaced, unique data of the lens system and data instructing the focusing method such as inner focus or front focus are transferred to the interchangeable lens with a built-in front group lens. hold it,
The objective is to provide a camera that allows focus selection that is most suitable for the optical system.

[Means to solve the problem]

In order to achieve the above object, in the lens interchangeable camera system of the present invention, in a lens interchangeable camera system having an automatic focusing position detection mechanism, a rear group lens including an inner focus lens on the camera body side and a rear group lens including an inner focus lens on the camera body side; a driving device for a lens for use in the camera, and the interchangeable lens side is provided with a front lens group consisting of one or more groups and an output means for outputting unique information regarding the front lens group that can be transmitted to the camera body, and outputting information from the output means. The camera body is provided with a control means for controlling the camera based on the unique information.

It is advantageous in terms of production if the unique information output means is an electrical output means.

Further, it is more practical to configure the front group lens as an afocal system and the rear group lens as an imaging system, since the camera functions even without the front group lens (interchangeable lens).

Furthermore, it may be advantageous depending on photographing conditions to configure the front group lens to include a front focusing lens and to provide means for driving the front focusing lens from the camera body side.

Furthermore, if the front group lens and the rear group lens each include a focusing lens, and one or both of them can be moved to perform focusing depending on the shooting conditions, the degree of freedom in shooting will increase and the practicality will be further improved. can be improved.

[Function] The interchangeable lens camera system configured as described above includes an inner focus lens within the camera body, so it is possible to take pictures using only the camera body.

Furthermore, by attaching an interchangeable lens to the camera body, full-scale interchangeable lens photography can be performed.

In addition, by selecting an interchangeable lens with a front focusing lens, you can choose whether to focus with the front group lens or the rear group lens, allowing you to take pictures using the optimal focusing method. In particular, when the interchangeable lens has a zoom function, the advantage of being able to focus with minimal change in aberration can be fully utilized.

〔Example〕

Examples will be described below with reference to the drawings.

Fig. 1 is a lens configuration diagram showing the optical system of one embodiment of a zoom lens used in a video camera.The front group is made up of a negative meniscus lens L1 with its convex surface facing the object side in order from the object side and a biconvex lens Lt. Lenses: a positive meniscus lens L3 with a convex surface facing the object side, a negative meniscus lens L4 with a convex surface facing the object side, a junction of a biconcave negative lens L and a positive meniscus lens L6, with a concave surface facing the object side. Negative meniscus lens L? , a positive lens La, and a biconvex positive lens L, forming an afocal optical system, L, , L
3. The magnification can be changed by moving L and .

In addition, the rear group lens has a biconvex positive lens 2 behind the aperture.
1. Positive meniscus lens with convex surface facing the object side 2□,
A positive power lens system consisting of a negative meniscus lens 13 with a concave surface facing the object side, a negative meniscus lens i4 with a convex surface facing the object side, and a biconvex positive lens l.
Focusing can be performed by moving s toward the object.

The lens configuration is such that zoom lenses with various magnifications can be configured by replacing the afocal zoom section of the front group. Therefore, it is possible to take pictures by removing the front group lens system and using only the rear group lens system, and by preparing and replacing a variety of afocal front group lenses with fixed magnification, it is possible to obtain various focal lengths from wide-angle to telephoto. You can enjoy taking photos.

Next, various embodiments shown in FIGS. 2 to 5 will be explained. First, in FIG. .

In addition, the camera body L has a light receiving section 4 that receives subject light via a half mirror 2 for automatic focusing, and a signal from the light receiving section 4 that indicates whether or not it is in focus, or if it is not in focus, an optical μmcom (M
a motor drive control circuit 6 that receives a signal corresponding to the judgment from the arithmetic circuit 5 and rotates the focus motor 8 forward, reverse, or stops the focusing motor 8;
Furthermore, a plunger 9 is provided which moves the focus motor 8, which rotates the drive gear 10 and the coupler 15, by means of a plunger control circuit 7.

An aperture mechanism 16 for adjusting exposure is provided in the middle of the rear lens group 13, and an electrical contact 18 is provided on the mount 17.

For this camera body l, the front group lens 20 of a type suitable for inner focus is shown in FIG.
In the one shown in FIG. 3, the front group lens 30 is of a type suitable for front focusing, and in the one shown in FIG. 41b, the one shown in FIG. 5 is equipped with a front group lens 50 of a type that has a built-in motor 52 and performs front focus and inner focus of the rear group lens system of the camera body l.

The front group lenses 20, 30, 40.degree. 50 of each lens type are each provided with a mount 27 and an electric contact 28 for detachably attaching them to the camera body 1.

Further, as shown in FIG. 3, the front group lens 30 of a type suitable for front focus is provided with a driven shaft 32 having a coupler 35 at its end that receives drive from the coupler 15 of the camera body 1. It is configured to drive a gear 36 that operates the focusing lens 31a of the front group lens system via a drive gear 33 and a relay gear 34 provided at the other end of the driven shaft 32.

Furthermore, as shown in FIGS. 4 and 5, a drive motor 42
Or the type of front group lens 40.50 with built-in 52 is,
It is configured to drive the focusing lens 41a or 51a via a drive gear 43 or 53, a relay gear 44 or 54, and a gear 46 or 56 that moves the lens system.

The operation will be explained below.

In FIG. 2, when the photographing switch (not shown) is closed,
The light receiving section 4 detects the imaging state of the photographing lens via the half mirror 2, and the information is input to the arithmetic circuit 5.

The arithmetic circuit 5 gives a control signal to the motor drive control circuit 6 in accordance with the arithmetic result based on the information from the light receiving section 4, and causes the motor 8 to rotate forward, reverse, or stop.

As a result, the inner focus lens 13 of the rear lens group provided in the camera body 1 is driven by the motor 8 via the drive gear 10, relay gear 11, and drive gear 12, and always maintains a focused state.

Further, in the case shown in FIG. 3, when the front group lens 30 is attached to the camera body 1, the electrical contacts 18 and 28 provided on the mount 17°27 are connected. Here, mount 17.2
The front group lens information provided in the fixed storage means 29 is transmitted to the arithmetic circuit 5 by the electrical contact 18.28 provided in the drive gear IO and the coupler 15. Equipped with a driven shaft
4 moves to the left in the drawing, the drive gear lO is removed from the relay gear 11 for inner focus, and the front lens group 3
The coupler 35 of the camera body 1 and the coupler 15 of the camera body 1 engage with each other.

Here, when the photographing switch (not shown) is closed, the light receiving section 4
detects the image forming state of the photographing lens via the half mirror 2, and inputs the information to the arithmetic circuit 5.

The arithmetic circuit 5 gives a control signal to the motor drive control circuit 6 in accordance with the arithmetic result based on the information from the light receiving section 4, and causes the motor 8 to rotate forward, reverse, or stop. As a result, the focusing lens 31a of the front group lens 30 moves and always maintains a focused state.

Further, in the case shown in FIG. 4, when the front group lens 40 is attached to the camera body I, the electrical contacts 18.28 provided on the mount 17.27 come into contact. And mount 17.27
The information provided in the fixed storage means 29 is transmitted to the arithmetic circuit 5 through the electric contact 28° 18 provided in the plunger control circuit 7, and the plunger 9 is controlled by the plunger control circuit 7. The driven shaft 14 moves to the right in the drawing, and the drive gear 10 is removed from the inner focus relay gear 1.

Here, when the photographing switch (not shown) is closed, the light receiving section 4
detects the image forming state of the photographing lens via the half mirror 2, and inputs the information to the arithmetic circuit 5.

The arithmetic circuit 5 outputs a control signal to the motor drive control circuit 6 in accordance with the arithmetic result based on the information from the light receiving section 4, and causes the motor 42 to rotate forward, reverse, or stop. As a result, the front group focusing lens 41a moves and always maintains a focused state.

In addition, the lens shown in FIG. 5 moves the focusing lens 51a of the front lens group 50 to maintain the in-focus state at all times, similar to the lens shown in FIG. If the amount of extension of the focusing lens 51a of the front group lens is insufficient, the lens system 13 on the camera body side
b to enable close-up photography.

Next, focus selection information to be stored in the fixed storage means 29 shown in FIGS. 2 to 5 will be explained.

The fixed storage means 29 digitally stores focus selection information for the front lens group, and transmits the information to the arithmetic circuit 5 on the camera body side via the electrical contacts 18 and 28 on the mount surface to select the focus selection information for the front lens group. Perform type identification.

Here, the identification signals of the A-D type front group lenses (interchangeable lenses) shown in Table 1 will be explained.

Table 1 Type A is an interchangeable lens that focuses only with the inner focus lens on the camera body side in the front group lens, and Type B has a front focus lens in the front group lens and is driven by a coupler driven by a motor on the camera body side. An interchangeable lens that performs focusing, the C type has a front focus lens in the front group lens and has a built-in motor, and the motor performs front focus.The D type has a front focus lens in the front group lens. It is an interchangeable lens that has a built-in motor and performs double focusing: the inner focus of the camera body and the front focus of the front group lens.

Next, information transmission will be explained with reference to FIG.

FIG. 6 is a block diagram showing information transmission, in which the right side of the dashed line is an electric circuit built into the camera body X, and the left side is an electric circuit built into the front group lens Y.

BT is the camera's power battery, and MS is a manually opened/closed power switch. When this power switch MS is closed, power is supplied from the power supply line (+E) to the microcomputer (hereinafter referred to as μ-Coi1) MCP and the oscillator OSC, and the oscillation operation is started.

When SW is closed, the input terminal ■ of p-com (MCP).

The “Lo11” signal is input to the “Lo11” signal.

When the input terminal ■ of p-cow (MCP) becomes "Lo-", the output terminal O5 becomes "old ghll" and the terminals Bo, P
Power is supplied to the circuit on the front group lens side via o.

Output terminal 0□ of μmcow (MCP) is terminal B on the camera side.

is connected to a counter CO and a glue set terminal RE via an input terminal P1 on the front group lens side and an inverter IN. This output terminal 02 is in the "old gh" state while receiving information from the front lens group, and the counter CO□ is set in the reset release state.

μ-corn (MCP) output terminal 0. outputs "tligh" as the serial data read signal. Then, the flip-flop FF is set and the AND gate AN+ is opened to output the output terminal 0 of μmcow (MCP).
4 is applied to the clock terminal CK of the 3-bit binary counter COI and the 8-bit shift register SR.

Counter C on the front group lens Y side (h is the reset terminal RE
When the input of "old gh" is received, the reset is canceled.

Output terminal B2 on the camera body X side sends a clock pulse from the camera body X to the front lens group Y side via the input terminal Pt in order to synchronize the electrical operation between the front lens group Y side and the camera body It is connected to the terminal (CL) of the counter CO□.

Counter CO2 is a 4-bit binary counter and counts the rising edge of the clock pulse from input terminal P2.

The 4-bit output 00 to C3 of the counter CO1 is input to a decoder 0H, and the decoder DB outputs the signals shown in Table 2 according to the contents of the counter CO□.

Table 2 Output from output terminals 0° to D of decoder〇H, only one signal is “Iligh” and all others are “Lo-” are selected according to the contents of counter CO□, and the output is OR gate OR , AND gates 8N0 to ANe, and switches S0 to S, and a signal is outputted to the input terminal (B3) of the camera body via the output terminal P3 and the setting switching means Z.

When the count of the counter CO□ advances by one, the decoder DE sets the output terminal D0 to ``gh''.At this time, the switch S0 of the setting switching means Z is open, so the AND gate AN is open. The "old gh" output signal from the decoder output terminal D0 passes through the AND gate AN, and transmits the "Ilight" information to the camera body side via the OR gate OR and terminals Pi and Bs.

When the counter advances to 2, the output terminal D+ is set to "old gh", and the AND gate AN of the setting switching means Z switches the switch S
, closed the gate because it has been revised.

The "old gh" output signal from the decoder output terminal D1 cannot pass through, and "Lo-" information is transmitted to the camera body. Similarly, as the clock pulse count progresses, one bit is serially output one by one.

The shift register SR on the camera body side is the clock terminal CK.
Information is taken in sequentially from the serial input terminal at the falling edge of the clock pulse.

When the 8th clock pulse rises, the counter CO
The carry terminal CY of No. 3 becomes "old gh", and at the fall of this pulse, the output to AN (anto-game) AN becomes "old gh". As a result, the counter COI and flip-flop FF are reset, and at the same time, the serial data cassette signal is changed to ``old gh++'' and μmcom (MC
P) is applied to input terminal I. μmcow (MCP)
receives a serial data human input signal and takes in data from the data bus DB.

SW2 is the second button when the release button (not shown) is pressed.
This switch SW is a release switch that is closed in stages.
2 is closed at the input terminal I2 of μmcow (MCP)
A “Low” signal is input to. μmcoII (MC
P) performs a series of exposure control operations and completes the operation when the input terminal (2) becomes "Lo-".

FIG. 7 will explain the operation of FIG. 6 based on a float yard showing the operation of μ-cow (MCP).

When the power switch MS is closed, μmcoIII(M
CP) and the oscillator O8C, and after resetting, the photometric switch SW in step #02 is closed and waits for "'Low" to be input to the input terminal I. When becomes "Low", in step #03, the output terminal O3 is set to "old gh" and power is supplied to the circuit on the front group lens Y side.

In step #04, the output terminal 02 is set to "old gh" and the counter CO! on the front group lens Y side is set. is set to the reset release state, and the front group lens information identification code checked flag FG is set.
3 and clear register C.

In step #07, 1 is added to register C, and °"flig is output from output terminal 03 as a serial data read signal.
h" to start reading the front group lens information,
Input terminal ■, more serial data as a cassette signal “
Wait for "old gh" to be input.

Then, receiving the serial data cassette signal, it is read into the register MC3 from the data bus DB, and it is determined whether the front group lens information identification code checked flag FG is "IH" or not.

If the flag FC is "IH", it means that the front group lens information identification code has been checked, and the process advances to step #17. Also, if the flag FG is not "IH", the process advances to front group lens information identification code check step #12 and the flag FC is set to "IH".
IH pa.

Next, in step #13, the front group lens information identification code read into register M+3 is determined, and the amount of information to be read from the front group lens into register D is 3H'', 41('', or 6H) depending on the code content. ”.

Then, in step #17, it is determined whether the register D has become "OH" or not.
After subtracting the value, return to step #07 and repeat steps #07 to #17 until the register D becomes "OH", thereby making it possible to read all of the front group lens information from the front group lens Y.

Therefore, when register D becomes "OH", serial data read signal output terminal 0. is set to "Lo-" and the reading operation is completed. With this operation, the front group lens with each information content of type A (Table 3) or type B (Table 4) is attached to the camera body X, and is stored in each register MC according to the front group lens information identification code. Taking the case where the data is read as an example, the contents of the register at that time are shown in Table 5 or Table 6.

Table 3 Type A front group table 4 Type B front group table 5 Register M information content table 6 Register M information content Next, in step #20, front group lens information identification code M
If 1 is greater than "F2H", the plunger control of the camera body and the motor control of the front group lens are executed, the release switch SW2 in step #25 is opened, and "old gh" is input to the input terminal ■2. If it is entered, step #2
0 and repeats steps #02 to #25.

On the other hand, the release switch S-2 is closed and the input terminal ■
When "Lo-" is input in step #2, the next exposure control is executed, all processing of the camera system is completed, and the process returns to step #01 to proceed to preparation for the next photographing.

Although this embodiment is a case in which the present invention is applied to a video camera, it goes without saying that the present invention can also be applied to a 35 mm camera.

〔Effect of the invention〕

The focusing method of zoom lenses is the front focus method, which moves the frontmost lens group of the optical system in the direction of the optical axis.
There are two types of methods: the entire optical system, which moves the entire optical system in the direction of the optical axis, and the inner focus method, which moves the lens system at the rear of the optical system in the direction of the optical axis.The front focus method, at any focal length, , focusing can be performed with approximately the same amount of extension, and has a great advantage over the entire extension method in which the amount of focusing movement differs depending on the focal length, or the method in which a part of the zoom lens is moved.

However, it is difficult to shorten close-range photography on the wide-angle side, resulting in problems such as an increase in the size of the lens system and large changes in aberrations as the object distance changes.

However, according to the lens conversion type camera system according to the present invention, it is possible to select the optimal focusing method for the optical system, maintain the low cost and reliable interlocking of the fixed zoom lens, and enable full-scale interchangeable lens photography. It has the effect of making it possible.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention. Fig. 1 is a detailed view showing the lens configuration of a zoom lens for a video camera used in the embodiment, and Figs. 2 to 5 show each type of front group lens. FIG. 6 is a block diagram of an electric circuit built into the camera body and front group lens, and FIG. 7 is a flowchart showing the operation of μmcom (MCP). 1...Camera body, 2...Half mirror 13...
Solid-state imaging device, 4... Light receiving section, 5... Arithmetic circuit, 6
... Motor drive control circuit, 7... Plunger control circuit, 8°42.52... Motor, 9... Plunger, 13... Rear group lens, 15... Coupler, 2
0, 30, 40° 50... Front group lens, 29... Fixed storage means, 17° 27... Mount, 18.28.
...Electrical contacts. □;l, j, l- Figure 1 Front group lens Rear group lens

Claims (7)

[Claims] (1) In an interchangeable lens camera system having an automatic focusing position detection mechanism, a rear group lens including an inner focus lens and a drive device for the inner focus lens are provided on the camera body side, and one group is provided on the interchangeable lens side. A front lens group consisting of the above and an output means for outputting unique information regarding the front lens group that can be transmitted to the camera body are provided, and a control means for controlling based on the unique information sent from the output means is provided on the camera body side. An interchangeable lens camera system characterized by the fact that it is equipped with a. (2) The interchangeable lens camera system according to claim 1, wherein the unique information output means is an electrical output means. (3) The interchangeable lens camera system according to claim 1, wherein the front group lens is an afocal system, and the rear group lens is an imaging system. (4) The interchangeable lens camera system according to any one of claims 1 to 3, wherein the front group lens includes a front focusing lens, and means for driving the front focusing lens from the camera body side is provided. (5) The unique information output from the unique information output means of the front group lens includes focus selection information indicating whether or not to focus on both or either of the front group lens and the rear group lens. 5. The interchangeable lens camera system according to claim 4. (6) Specific information storage regarding the afocal front group lens including the front focusing lens and the front group lens including focus selection information on whether or not to focus on both or either of the front group lens and the rear group lens. means, focus selection information in the unique information storage means,
An interchangeable lens for an interchangeable lens camera system, comprising a front focusing lens drive motor that operates in response to a signal from a camera body. (7) The inner focusing lens is configured to be driven by a motor via a gear mechanism, the motor is linked to an electromagnetically driven plunger, and the drive gear connected to the motor shaft is connected to the gear mechanism by a signal from a control circuit. A driving mechanism for a focusing lens for an interchangeable lens camera system, characterized in that the driving mechanism is configured to be engaged with and disengaged from the lens.