JPS6287921A - Zoom lens macro mechanism control device - Google Patents

Abstract

PURPOSE:To prevent the return of a macrolever to a normal position from being forgotten by controlling a motor by a motor control circuit so that a macrolens is located on a normal photographing position interlocking with the operation of a camera power supply switch. CONSTITUTION:When the macrolens 22 is controlled on the normal photographing position, the output voltages of the 1st and 2nd inversional amplifiers 10, 11 are turned to the same potential, the potential difference between both the input terminals T1, T2 of the motor MT is turned to '0' and the motor MT is stopped. A delay circuit 9 having a delay time longer than a series of the control time generates an output signal to a switching control circuit 8 for a switch SW3 after said control, the switch SW3 is switched from a contact M to a contact N, the input terminals T1, T2 of the motor MT are shorted and the motor MT is braked so as not to be rotated by external force. Even if the macroswitch SW1 is set up to either contact, the macrolens 22 is always located on the normal photographing position at the start of photographing. Since the macrolens is returned to the normal position after macrophotographing, defocused photographing can be completely removed.

Description

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

(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.
The macro lever is connected to a part of the optical system of the zoom lens, and after removing the locking mechanism by rotating the macro lever around the lever axis or pulling it in the radial direction during close-up photography,
By rotating the lens around the optical axis from the normal 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 image will be out of focus and 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 in the normal position, shots taken at infinity will be blurred, regardless of whether the macro lever is near or far from the normal position.

(Objective of the Invention) The present invention solves these drawbacks and enables zooming without returning the macro lever to the normal position. Another object of the present invention is to obtain a lens macro mechanism control device.

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

(Example) Fig. 1 shows an external view of a television camera equipped with the 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 various servo circuits. The servo unit 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 into a unit, and is electrically connected to the servo unit 3 by a cable 5.

Since it is detachably attached to the unit 3, the macro mechanism can be controlled remotely by replacing the cable 5 with a longer cable and removing the macro control unit 4 from the servo unit 3.

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 and a macro operation member 20.

The macro switch SW 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. Hereinafter, regarding the contacts of the various switches, the one that is connected during no-mo photography will be referred to as the N contact, and the one that is connected during macro photography will be referred to as the M contact. Here, the macro switch SW1 is composed of an electromagnetic slide switch, and when the power switch 30 of the television camera is turned on, a pulse is output from the one-shot multi-by-break 14, and current flows from the switching control circuit 13 to the coil 15 for a certain period of time. The macro switch SW1 is forcibly switched to the N contact side, that is, to the normal shooting side. The macro operation member 20 is interlocked with a potentiometer P and generates a macro control signal. The macro control signal is input to the M contact of the switch SW2 via the cable 5, and is input 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 SWt. 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 connected to one input terminal T of the motor MT for driving the macro mechanism 21 and the second inverting amplifier 1
The configuration is such that it is input to one input terminal. The output terminal of the second inverting voltage switch 11 is connected to the M contact of the switch SW3, and the output terminal of the switch SW3 is connected to the other input terminal T2 of the motor MT. The N contact of the switch SW is connected to the input terminal T and is configured to form a short circuit. Macro switch SW consists of an electromagnetic slide switch.

The outputs thereof are connected via a cable 5 to a switching control circuit 7 of a pull-down resistor R2, a delay circuit 9, and a switch SW, respectively. The output of the delay circuit 9 is connected to the switching control circuit 8 of the switch SW3. Motor MT is macro mechanism 21
The output of the potentiometer P2 is connected via a resistor R4 to the inverting input terminal (
-).

Next, the operation will be explained.

When the power switch 30 of the television camera 1 is turned on before shooting, the one-shot multi-pipe rake 1 is activated as described above.
4 outputs a pulse, current flows from the switching control circuit 13 to the coil 15, and no matter which contact the macro switch SWI is in, it is initially set so as to forcefully switch to the N contact side. When the macro switch SWl is connected to the N contact, the input of the switching control circuit 7 of the switch S W z is grounded via the pull-down resistor R2 and becomes a low potential, which is detected and the switch SW2 is switched to the N contact.

A reference voltage generation circuit 6 that generates a reference voltage for controlling the macro lens 22 to the normal photographing position is connected to the N contact, and the reference voltage signal is connected to the inverting input terminal ( -), and the output of the first inverting ground width converter 10 is input to one input terminal T of the motor.

Further, the output of the first inverting width device 10 is transmitted to the second inversion width device 11.
is input to the inverting input terminal (-) of the second inverting ground width device 1.
1 is input to the other input terminal T2 of the motor MT via the M contact of the changeover switch SW3, and drives the motor MT. Further, the potentiometer P2 rotates in conjunction with the motor, and the output voltage generated by the potentiometer P2 is inputted to the addition circuit composed of the inverting amplifier 10 via the resistor R4, and then to the inverting amplifier 10 via the resistor R3. The voltage is calculated from the input reference voltage generation circuit 6, and the motor MT rotates until it reaches an equilibrium state.

Therefore, the macro lens 22 is in the normal shooting position (reference position).
When controlled, the first and second double inverting amplifiers 10.11
The output voltages of the motor MT become the same potential, and the potential difference between the re-input terminals T I and T 2 of the motor MT becomes 0, and the output voltage of the motor MT becomes the same potential.
stops. The delay circuit 9, which has a delay time longer than the time required for the series of controls described above, issues an output signal to the switching control circuit 8 of the switch SW after the series of controls described above is performed. However, the switches SW and I are switched from the M contact to the N contact, short-circuiting the input terminals T + and T z of the motor MT, and braking the motor MT so that it does not rotate due to external force. As mentioned above, no matter which macro switch sW is set, macro lens 2 is always set at the start of shooting.
2 is at the normal shooting position. Therefore, after macro photography, the macro switch sw.

The inconvenience caused by forgetting to return the terminal to the N contact is eliminated.

Next, during macro photography, when the macro switch SW is switched to the M contact side, a voltage signal determined by the resistors R+ and Rz is input to the switching control circuit 7 and the delay circuit 9, and the changeover switch SW2 switches from the N contact to the M contact. Then, the switching control circuit 8 operates via the delay circuit 9, and the changeover switch SW3 is switched from the N contact to the M contact, 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 P1 linked thereto, and a voltage corresponding to the operation amount is transmitted to the re-input terminals T, , T2 of the motor MT.
The macro mechanism 21 operates and the macro lens 2
2 moves in the optical axis direction, and when the potentiometer P2 moves by the amount of movement corresponding to the operation amount, the potentiometer P2 interlocks with the motor M.
The signal is input to an adder circuit composed of an inverting amplifier 10, and when it is calculated and an equilibrium state is reached, 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 cent, 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 maintained without any operation, so there is no possibility of out-of-focus photography.

[Brief explanation of drawings]

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)

Claims (1)

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