JPH0575088B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention further shortens the minimum photographing distance by moving a part of the optical system of a zoom lens onto the optical axis, thereby enabling macro photography (close-up photography). The present invention relates to a control device for a macro mechanism that enables

(Background of the Invention) Among conventional zoom lenses, taking as an example the macro mechanism of a zoom lens for a television camera, a manual lever (macro lever) is provided on the outer periphery of the lens barrel and protrudes in the radial direction. It is connected to a part of the optical system of the zoom lens. During close-up photography, the macro lever is rotated around the lever axis or pulled in the radial direction to remove the lock mechanism, and then rotated around the optical axis of the lens to return to normal mode. By rotating from the position to the macro position, a part of the optical system moves in the optical axis direction, allowing close-up photography.

Because of this structure, normal photography may be performed without returning the macro lever to the normal position by mistake. In that case, if the macro lever position is close to the normal position, it may be possible to focus by adjusting the focus ring under shooting conditions where the object distance is not infinite; If you zoom backwards, the focus will shift and the image will be blurry, and if the macro lever is far from its normal position, you will not be able to focus even if you adjust the focus ring.

Of course, if the macro lever is not at the normal position, shots taken at infinity will be blurry, regardless of whether the macro lever is near or far from the normal position.

(Object of the Invention) An object of the present invention is to solve these drawbacks and provide a macro mechanism control device for a zoom lens that does not cause the macro lever to be returned to the normal position.

(Summary of the Invention) The present invention provides a switch linked to the power switch of the camera, and forcibly controls the macro mechanism to the normal state when the power switch of the camera is turned off or on. The technical point is to control the circuit so that it short-circuits.

(Example) FIG. 1 shows an external view of a television camera equipped with a macro control device of the present invention, in which 1 is the television camera body, 2 is a zoom lens with a built-in macro mechanism, and 3
is a servo unit that has various built-in servo circuits, and has an easy-to-grip external shape, and includes built-in servo circuits for auto-iris, zoom, focus, macro, etc. Reference numeral 4 denotes a macro control unit in which a portion and a circuit for controlling the macro mechanism are integrated, and is electrically connected to the servo unit 3 by a cable 5.

Since the macro control unit 4 is detachably attached to the servo unit 3, the cable 5 can be replaced with a longer cable to connect the macro control unit 4.
By removing the servo unit 3 from the servo unit 3, the macro mechanism can be controlled remotely.

FIG. 2 is a block diagram showing one embodiment of the present invention. The macro control unit 4 includes a manually operated macro switch SW ₁ and a macro operation member 20.
is built-in.

The macro switch _SW1 is an on/off switch of the macro control device of the present invention, and is manually switched to the N side of the contact (N contact) during normal photography and to the M side of the contact (M contact) during macro photography. Regarding the contacts of the various switches, those connected during normal photography will be referred to as N contacts, and those connected during macro photography will be referred to as M contacts. here macro switch
SW ₁ consists of an electromagnetic slide switch, and when the TV camera's power switch 30 is turned on, a pulse is output from the one-shot multivibrator 14, and current flows from the switching control circuit 13 to the coil 15 for a certain period of time, forcing it to Macro switch SW ₁
The configuration is such that the switch is switched to the N contact side, that is, the normal shooting side. The macro operating member 20 is interlocked with a potentiometer _P1 and generates a macro control signal. The macro control signal is inputted to the M contact of the switch _SW2 via the cable 5, and is inputted to the inverting input terminal (-) of the operational amplifier ₁₀ via the resistor R3. A reference voltage generation circuit 6 is connected to the N contact of the switch _SW2 . A predetermined voltage is applied to the non-inverting input terminal (+) of the first inverting amplifier 10. The output of the inverting amplifier 10 is configured to be input to one input terminal T ₁ of the motor MT for driving the macro mechanism 21 and to the input terminal of the second inverting amplifier 11 . the second inverting amplifier 1
Connect the output terminal of 1 to the M contact of switch SW ₃ ,
The output terminal of the switch SW ₃ is connected to the other input terminal T ₂ of the motor MT. The N contact of the switch SW ₃ is connected to the input terminal T ₁ and configured to form a short circuit. The output of the macro switch SW ₁ consisting of an electromagnetic slide switch is connected via a cable 5 to a pull-down resistor R ₂ , a delay circuit 9,
They are respectively connected to the switching control circuit 7 of the switch SW ₂ . The output of the delay circuit 9 is connected to the switching control circuit 8 of the switch _SW3 . The motor MT is configured to drive the macro mechanism 21 and to operate in conjunction with a potentiometer _P2 , and the output of the potentiometer _P2 is connected to the inverting input terminal of the first inverting amplifier 10 via a resistor _R4 . -).

Next, the operation will be explained.

When the power switch 30 of the television camera 1 is turned on prior to shooting, a pulse is output from the one-shot multivibrator 14 as described above, current flows from the switching control circuit 13 to the coil 15, and the macro switch SW ₁ is connected to either contact point. The initial setting is such that it will forcefully switch to the N contact side no matter what happens. When macro switch SW ₁ is connected to N contact, the switch
The input of SW ₂ switching control circuit 7 is a pull-down resistor
It is grounded through _R2 and becomes a low potential, which is detected and the switch _SW2 is switched to the N contact. The N
At the contact point, there is a reference voltage generation circuit 6 that generates a reference voltage to control the macro lens 22 to the normal shooting position.
is connected, the reference voltage signal is input to the inverting input terminal (-) of the first inverting amplifier 10, and the output of the first inverting amplifier 10 is input to one input terminal _T1 of the motor.

Further, the output of the first inverting amplifier 10 is input to the inverting input terminal (-) of the second inverting amplifier 11, and the output of the second inverting amplifier 11 is input to the M of the changeover switch _SW3.
The other input terminal of the motor MT via the contact
Input to _T2 and drive motor MT. or,
The potentiometer P ₂ rotates in conjunction with the motor, and the output voltage generated by the potentiometer P ₂ is inputted via a resistor R ₄ to an adder circuit composed of an inverting amplifier 10, and then connected to a resistor R ₃ . The voltage of the reference voltage generation circuit 6 is input to the inverting amplifier 10 through the
MT rotates.

Therefore, when the macro lens 22 is controlled to the normal photographing position (reference position), the output voltages of the first and second bi-inverting amplifiers 10 and 11 become the same potential, and both input terminals T ₁ and T of the motor MT The potential difference between _them becomes 0, and the motor MT stops. The delay circuit 9, which has a delay time longer than the time required for the series of controls described above, is configured to switch after the series of controls described above is performed.
An output signal is sent to switching control circuit 8 of SW ₃ , switch SW ₃ is switched from M contact to N contact, and input terminals T ₁ and T ₂ of motor MT are short-circuited to prevent motor MT from rotating due to external force. Braked.
As described above, regardless of the setting of the macro switch SW ₁ , the macro lens 22 is always at the normal shooting position at the time of starting shooting. Therefore, the inconvenience caused by forgetting to return the macro switch _SW1 to the N contact after macro photography is eliminated.

Next, when shooting macro, set macro switch SW ₁ to M.
When switching to the contact side, a voltage signal determined by resistors R ₁ and R ₂ is sent to the switching control circuit 7 and the delay circuit 9.
is input, the changeover switch SW ₂ is changed from the N contact to the M contact, the changeover control circuit 8 is operated via the delay circuit 9, and the changeover switch SW ₃ is changed from the N contact to the M contact.
The switch is switched to the contact point, and macro photography becomes possible. When the macro operation member 20 is operated, a voltage (macro control signal) corresponding to the operation amount is generated from the potentiometer P ₁ linked thereto, and a voltage corresponding to the operation amount is applied to both input terminals T ₁ of the motor MT,
T ₂ occurs, the macro mechanism 21 operates and the macro lens 22 moves in the optical axis direction, and when it moves by the amount of movement corresponding to the operation amount, it is reversed by the potentiometer P ₂ linked to the motor M. amplifier 10
When the input signal is input to an adding circuit composed of the following, and an equilibrium state is reached by calculation, the motor MT is stopped and the macro lens 22 is fixed at one point on the optical axis, making macro photography possible.

In the above embodiment, when the power switch 30 of the television camera is turned on, the macro lens 22 is forcibly driven to the reference position to perform the initial setting, but when the power switch 30 is turned off, the macro lens 22 is initially set to the reference position. It may be configured as follows.
Furthermore, although the embodiments have been described with respect to the zoom lens of a television camera, the present invention is not limited thereto, and can also be applied to a zoom lens of a cine camera, for example.

(Effects of the Invention) As described above, according to the present invention, when taking another photograph after macro photography, the normal state is established without any operation, so there is no possibility of out-of-focus photography.

[Brief explanation of the drawing]

FIG. 1 is an external view of a television camera equipped with a macro control device of the present invention, and FIG. 2 is a block diagram showing an embodiment of the present invention. Explanation of symbols of main parts, 1...TV camera,
2...zoom lens, 3...servo unit, 4
... Macro control unit, 5 ... Cable, P ₁ , P ₂ ... Potentiometer, SW ₁ , SW ₂ ,
SW ₃ ...Switch, _R1 , _R2 , _R3 , _R4 ...Resistance,
6... Reference voltage generation circuit, 7, 8, 13... Switching control circuit, 9... Delay circuit, 10, 11... Inverting amplifier, 14... One-shot multivibrator, 30... Power switch.

Claims (1)

[Claims] 1 Consists of a motor control circuit that controls a motor for moving the macro lens, and a macro operation member that sets the position of the macro lens in the optical axis direction, and the motor control circuit moves the macro lens normally in conjunction with the operation of the camera power switch. A macro mechanism control device for a zoom lens, characterized in that the motor is controlled so as to be positioned at a photographing position.