JPS5843433A - Driving device for diaphragm of lens using pulse motor - Google Patents

Abstract

PURPOSE:To obtain a lens diaphragm device using a stable and sure pulse motor by running the pulse motor reversely on starting of releasing thereby putting the diaphragm into a full aperture state. CONSTITUTION:When a photometric switch 12 is closed on starting of releasing, reverse running pulses are generated from the output terminal B of a photometric circuit 13, and a pulse motor 18 is run reversely by a pulse motor driving circui 17, by which a diaphragm mechanism is so controlled as to be located in a full aperture state at all times. Thus the diaphragm is controlled always from the correct initial position and the lens diaphragm device using the stable and sure pulse motor is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a device for driving an aperture of a photographic lens by a pulse motor.

For example, it has been known to use a pulse motor to step-drive the aperture device of a lens attached to a single-lens reflex camera for taking pictures. The lens aperture is designed to return to its initial position (open aperture) when the power is turned off, but if some force is applied to the aperture device and the pulse motor moves, the aperture will return to its initial position (open aperture). There was a drawback that the value would be incorrect.

The object of the present invention is to obtain a pulse motor-driven diaphragm device which eliminates the drawbacks of the conventional device as described above, and thereby constitutes a stable and reliable motor-controlled diaphragm lens device. That is, in the device of the present invention, by applying a reverse pulse to the pulse motor before releasing the lens to bring the lens into the open aperture state, the lens is always brought into the open aperture state during photometry. be.

Another method is to apply more reverse pulses to the pulse motor than the number of pulses narrowed down for the previous shot when the shutter is inactive and the winding switch is turned on.
There is also a method to ensure that the aperture hits the stopper when it becomes an open cape. Temporarily using these five methods,
In order to prevent the aperture from bouncing off the stopper, it is also effective to lengthen the pulse period when the aperture is close to the open aperture.

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 camera using an aperture driving device according to the present invention. In the figure, reference numeral 1 denotes an accessory seam, which is used for attaching accessories such as a strike device. , 2 is the finder, 6 is the camera body, 4 is the lens device,
Ru. 5 is a pulse motor; 16 is a battery; these are arranged within the housing of the lens device 4; 7 is a lens, and 8 is an aperture of the lens. , 9 is 3″81″v-wyfi-vM...□j轡, ;<yp
y7r:b:b FIG. 2 is a circuit connection diagram showing an embodiment of the diaphragm driving device according to the present invention. In the figure, the left side of the connection terminals 14, 15, 15' and 16 is a circuit inside the camera body, and the right side is a circuit inside the lens device. 10 is turned so that power is also supplied to the power supply device side. 12 is a photometric switch, 11 is a resistor, and 16 is a photometric circuit known as SP.
This is an electronic circuit that includes a D light receiving element and the like. 19 is a winding switch, and 20 is a film winding motor. The output of the photometric circuit 16 is sent through a terminal 15.15'' to a pulse motor drive circuit 17 on the lens side, and the output pressure of the lens 17 drives a pulse motor 18 in steps.

FIG. 6 is a timing chart for explaining the operation of the circuit of FIG. 2. Next, the operation of the circuit shown in FIG. 2 will be explained with reference to FIG. Figure 2 - First side/Light switch 1
Turn on 2. and the output B of the photometric circuit 16 as shown in Fig. 151.
A reverse pulse as indicated by Vc is generated and is input to the pulse motor drive circuit 17 through the seventh element 15'. Due to this pulse signal, motor driving pulses are generated in the order of Li-+L2→Ll(7) at the outputs Ll, L2 and L5 of the circuit 17 as shown in FIG. L5.
L2. The pulse motor 18 rotates step by step in the opposite direction, opening the aperture of the lens.

Next, when the camera side pressure aperture value is set, the photometry circuit 16
A signal such as 15 in FIG. 3 is output from the output A of , and a forward rotation pulse such as 11m3 as shown in FIG. 15' is output from the output 15'. The number of pulses corresponds to the set aperture value. This pulse is applied to the lens-side palm motor drive circuit through the Shinshu Rikiki terminal 15.15'-, and its output L1.
L2. Pulses as shown in FIG. 3 are generated sequentially at L's. As a result of this, the pulse motor 18 advances in the forward direction, and when the aperture of the lens reaches the aperture value set by the camera side pressure, the rotation of the motor 18 stops. In this state, the film is exposed by the layer release operation, and when this is completed, the winding switch ≠19 is turned on. This causes the winding motor 20 to rotate and wind the film, and at the same time pulse No. 146 is generated by the outputs A and B of the photometric circuit 16, which is applied to the pulse motor drive circuit on the lens side and changes its output/power. .

IJl, L2. IJl, Ll in Figure 6, IJ
2. A reversal pulse as shown at L3 is generated, which causes the motor 18 to reverse and open the aperture. At the open aperture position of the lens, the aperture member is stopped by a stopper, and even if this reversal pulse is input more than the set aperture step, the motor will stop reversing at the open aperture position.

As described above, in the lens diaphragm driving device of the present invention, when the photometry switch is turned on or the winding switch is turned on, the diaphragm becomes open, and then the diaphragm is further driven in the open direction. Since the camera is designed to apply a reverse pulse to the palm recorder, the aperture drive will always start from the open aperture state when shooting starts, even if the print is off the open aperture for some reason. This allows you to always obtain an accurate aperture value.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of a camera equipped with a lens using the aperture drive device of the present invention, the second grip is a circuit connection diagram showing an embodiment of the aperture drive device according to the present invention, and FIG. 2
3 is a timing chart for explaining the operation of the circuit shown in the figure. 10...Power battery, 12...Photometering switch, 16.
Salary/photometering circuit, 14, 15.15', 16...Connection terminal between camera body and lens -17.../<Russ motor drive circuit, 18...Pulse motor -119... Winding switch, 20...Motor for winding the rim. Patent applicant: Canon Co., Ltd. 2 Hatake

Claims (1)

[Claims] (1) A pulse motor is used, characterized in that the lens device, which uses the pulse motor to drive the aperture mechanism of the lens to advance it to the set aperture value, is equipped with a pulse motor drive means that always keeps the aperture in the open aperture position. Lens aperture drive device. (2) A lens diaphragm driving device using a pulse motor according to claim (1), characterized in that the aperture mechanism is moved by the pulse motor.