JPS5838938A - Lens device having electromagnetically driven diaphragm - Google Patents

Abstract

PURPOSE:To eliminate the clatters between a stopper and a gear and to decrease the errors in an aperture value by passing electric current in an opposite direction to a diaphragm meter while the diaphragm is held stopper by electromagnetic driving. CONSTITUTION:When a photometric switch of a camera is turned on and a shutter switch is turned on, a stopper pawl 13 is attracted by a magnet 14 and is released from the tooth parts of saw teeth 12 by overcoming the force of a spring 13'. When a meter 11 is driven and a set aperture value is attained, a stopper is engaged; at the same time, electric current flows in an opposite direction in a circuit L 1, by which the mechanical clatters of the diaphragm mechanism are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens device equipped with a pulse motor for driving an aperture device in a photographic lens device mounted on a camera.

- Conventionally, a method has been proposed in which a pulse motor is incorporated into a lens device in order to drive the diaphragm mechanism of a photographic lens attached to a flex camera using a stepping motor driven by a pulse signal. As described above, a difference in exposure amount VCvA may occur due to the aperture 9 being moved by the pulse motor.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the mechanical play when the aperture is stopped, which is a disadvantage of conventional devices as described above, and to provide a photographic lens device equipped with a lightweight and compact electromagnetic device for driving an aperture. It is.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a front view showing an example of a single-lens reflex camera equipped with a lens device according to the present invention.

In the figure, 1 is the camera body, 2 is the lens, 6 and 4
is the lens drive motor, 3 is for zoom adjustment,
4 is a distance adjustment device, and 5 is a lens aperture mechanism.

On the camera body 1@, 6 is a release button, 7 is a viewfinder, and 8 is an accessory shoe. The photographic lens device has a protruding part in one direction from the lens barrel, and a drive motor etc. is built into the protruding part. It is arranged so that it faces sideways or downwards as shown in the figure.

FIG. 2 is a route diagram showing an embodiment of the aperture drive section of the lens according to the present invention, in which numeral 9 indicates a variable resistor linked to the aperture blades, and 10
11 is an aperture blade, 11 is an electromagnetic mechanism (meter) that drives the aperture blade, 12 is a member having saw teeth that interlocks with the aperture blade, 13 is a stopper that engages with the saw teeth of 12, and 161 is a part of the stopper 16 that is connected to the saw tooth. Spring 1, 14 that biases in the direction
is an electromagnetic magnet that releases the stopper 16.

FIG. 3 is a circuit connection diagram showing an example of the circuit configuration of the lens device according to the present invention. Reference numerals 23, 24, and 25 in the figure are connectors that connect the camera body and the lens device, and the lens is attached to the camera body. Then, it is connected to the (1) and ←) poles of the power supply inside the camera body and the control signal terminal. Reference numeral 15 in the lens device is an aperture control circuit which inputs a control signal from a terminal 24 and outputs an aperture setting value ■^. 16 is a comparator that outputs the output V of the aperture control circuit.
^ and the voltage at the dividing point of the reference voltage VK are compared, and the meter L1 and magnet L2 are activated depending on the output.

17.18, 20.21 are diodes, 19.22 are resistors, and the resistor 22 constitutes a voltage dividing circuit for the reference voltage vK together with the variable resistor 9 linked to the aperture blades.

! jg4 diagram! 3 is a timing chart showing the operation of the apparatus shown in FIGS. 2 and 3; FIG.

In the figure, when the camera's photometry switch sw1 is turned on and then the shutter switch 8W2 is turned on, the stopper claw 13 is attracted by the magnet 14 and spring 13'
It is released from the tooth portion of the sawtooth 12 against the force of . Next, the meter 11 is driven and when the set aperture value is reached, the stopper is engaged, and at the same time, current flows through KL1 in the opposite direction as shown in Figure 4, thereby eliminating mechanical play in the aperture mechanism. In the circuit shown in FIG. 3, when the camera-side switches sw1 and SW2 are turned on, a signal is input to the terminal 24, and this signal is applied to the aperture control circuit 15. When the output V^ is output from the aperture meter 15, a current Ll in FIG. 4 flows from left to right to the aperture meter 11, and the aperture meter 11 is driven. The voltage divided by the resistor 9 and the resistor 22, which are connected to the aperture mechanism, is the inverting input of the comparator 16, and the output 15 is the non-inverting input of the comparator 16. Due to the interlocking of resistor 9, the voltage of the inverting input becomes V^
When it becomes higher, the output of comparator 16 is inverted,
As shown by Ll in FIG. 4, a small current flows through the aperture meter 11 from right to left. This current causes the claws 16 and saw teeth 12 shown in FIG. 2 to engage with each other, thereby eliminating play in the aperture blades.

As described above, in the lens device of the present invention, when the aperture is stopped due to the electromagnetic drive, by flowing a current in the opposite direction to the aperture meter, the looseness between the stopper and the teeth of the gear can be eliminated. It is possible to reduce errors in the aperture value than K, and has a great effect in making the automatic aperture operation of a lens device equipped with an electromagnetically driven aperture mechanism extremely stable and reliable.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of a single-lens reflex camera equipped with a lens device according to the present invention, FIG. 2 is a route diagram showing an example of an aperture drive section of the lens device according to the present invention, and FIG. FIG. 4 is a circuit connection diagram showing one embodiment of the circuit configuration of the lens device according to the invention, and FIG. 4 is a timing chart showing the operation of the lens device shown in FIGS. 2 and 6. 9... Variable resistor linked to the aperture blade, 10... Aperture blade, 111'' meter for driving the aperture blade, 12... Sawtooth member linked to the aperture blade, 13... Stopper,
14... Electromagnetic magnet, 15... Aperture control circuit,
16... Comparator O

Claims (1)

[Scope of Claims] A lens device equipped with a driving diaphragm, comprising a sawtooth rotating member that interlocks with the electromagnetically driven diaphragm and a stopper member that meshes with the sawtooth, and that rotates the aperture blades by the electromagnetic drive. A lens having an electromagnetically driven diaphragm, characterized in that when stopping due to engagement between teeth and a stopper, a current is passed through the electromagnetically driven diaphragm member in the opposite direction to that when the diaphragm laminate is rotated several times to stably stop the diaphragm plate. Device.