JPS60249123A - Pulse driving shutter - Google Patents

Abstract

PURPOSE:To obtain a shutter speed enough for practical use over the whole area of a disphragm by providing two diaphragm holes each different in shape on two pieces of sector serving as a diaphragm, and changing the combination of overlapped diaphragm hole in accordance with a turning direction of a pulse motor. CONSTITUTION:Each sector serving as a diaphragm 4 and 5 is provided with each diaphragm holes, 7, 8 different in shape, respectively, and in the initial position where a motor 1 is not operated, these diaphragm holes are in a position shifted from an optical path of a photographic lens 12, and a shutter remains closed. As for the shape of the diaphragm hole 7 and 8, when the motor turns counterclockwise and the hole 7 is overlapped, the diaphragm is opened by two steps each at every one step angle theta8, diaphragms of F32, 16, 4 and 2 are made at each stable point, and in case the motor turns clockwise and the diaphragm hole 8 is overlapped, its shape is set so that the diaphragm is varied to F22, 11, 5.6, 2.8 and 1.4, and in accordance with the diaphragm value, the turning direction of the motor is selected. In such a way, the opening and closing time of the shutter in case the motor is rotated by a driving pulse of the same frequency goes to 1/2 of a conventional time in case of other diaphragm than the minimum diaphragm.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to a camera shutter, and more particularly to an aperture shutter driven by a pulse motor.

(Prior art) In the conventional pulse-driven dual-purpose shutter, the first
As shown in the figure, two blades 4 each have one multi-hole 6.
, 5 are connected by a drive lever 2, and a pulse motor 1
Input one pulse to the motor and move it in one direction (left in the figure).
Each time the step angle is rotated, the blades are moved in opposite directions to open the aperture one step at a time. After obtaining the desired aperture aperture by the number of pulses, input the same number of pulses to reverse the motor and open the aperture. It was like closing. As shown in Figure 2, in this type of shutter, there are many rotational steps between opening and opening, and therefore it is necessary to input many pulses to rotate the motor greatly, and it takes a long time to open and close the shutter blades. The disadvantage is that the upper limit of the shutter speed is extremely slow because of the

(Summary of the invention) The present invention makes it possible to obtain a faster shutter speed than conventional shutter speeds even when the aperture is wide open, and to achieve a shutter speed that is sufficient for practical use even when using a small pulse motor that lacks frequency response. The purpose of this is to provide a pulse-driven programmable shutter that can be obtained over the entire range (aperture). Two sets of aperture holes with different shapes are provided in the shutter blades that also serve as apertures, and the shutter blades are designed to provide a pulse-driven programmable shutter that can be used over the entire range (aperture). The configuration was such that the first exposure aperture was determined by one of the sets.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a perspective view showing an embodiment of the present invention, and the same members as in FIG. 1 are designated by the same reference numerals.

The shutter blades 4 and 5, which also serve as an aperture 9, are provided with two aperture holes 7 and 8 of mutually different shapes, and in the initial position where the motor 1 does not operate, these aperture holes are used for the photographing lens 120.
There is a reed out of the optical path, and the shutter is closed. From this state, when the drive lever 2 rotates in the left direction indicated by the solid line arrow due to the rotation of the motor, the blades 4 and 5 connected to the lever 2 by the pin and the elongated hole are guided by guide members (not shown), respectively, as shown by the solid line arrow. The aperture holes 7 overlap each other to form an exposure aperture, and the aperture area increases according to the rotation angle of the motor. Also, when the motor rotates from the initial position in the direction of the arrow shown by the dotted line, blades 4 and 5
The diaphragm holes 8 are moved straight in the direction of the dotted arrow, and the diaphragm holes 8 overlap each other to form an opening.

The shape of the aperture holes 7 and 8 is as shown in Fig. 4. When the motor rotates counterclockwise and the holes 7 overlap, the number of aperture holes 7 and 8 opens two steps at a time for each step angle θ8 of the motor. 32,16
, 4.2 apertures are made at each stable point, and when the motor rotates to the right and the aperture holes 8 overlap, the number is F22.11.5,
The shape is set so that it changes as 6, 2, 8, and 14, and the rotation direction of the motor is selected according to the throttling value.

By doing this, the opening/closing time of the shutter when the motor is rotated with a drive pulse of the same frequency is the same as before for the smallest number of numbers, but remains the same as before for other numbers of numbers.

Figure 5 is a diagram showing the relationship between the aperture value and the exposure time in the case where multiple stages are opened one step at a time for each pulse in the conventional method.
Reference numeral 5 indicates a pulse for opening the shutter, and reference numerals 1' to 5' indicate pulses for closing the shutter. FIG. 6 shows the relationship between the aperture value and the exposure time in this embodiment, and the same number as in FIG. 5 can be obtained by pulses 1 to 3 and 1' to 6'.

Figure 7 shows a modification of the shape of the diaphragm hole.
5 includes aperture holes 7' having different shapes and sizes.

8' are provided respectively. Although the figure shows only the blade 5, the blade 4 is also provided with corresponding diaphragm holes 7L and 8/.

In this case, as shown in Figure 8, the motor rotates one step angle at a time to the left from the initial position to open the throttle hole 7'.
When the numbers overlap, the number changes step by step to F32, 22, 16°11.8, and the motor rotates to the right to open the diaphragm hole 8'.
When they overlap, the number changes step by step to F5, 6, 4, 2°1.4.

All of the above embodiments have the effect of increasing the shutter speed compared to the conventional one, but Figures 9 and 10 show that there is a difference especially in large numbers. be.

In FIG. 9, B is a program diagram of the number of limits and shutter speeds that can be combined in the conventional shutter system, and A is a program diagram that can be combined in the case of the embodiment of FIG.

Also, Fig. 10 compares program A' that can be combined with the conventional program B in the case of the embodiment shown in Fig. 7. Comparing both figures, it is found that in the case of Fig. 9, the combination is possible from wide open to small aperture. Since it has the effect of increasing the shutter speed for all apertures, it is suitable for a general program shutter, whereas in Fig. 10, a large speed increase effect can be obtained only for a large number of apertures that are close to the aperture, so for example, This is effective when shooting with a telephoto lens, where the shutter is often released at an aperture close to wide open.

Furthermore, it goes without saying that any program can be obtained by appropriately combining the shapes of the diaphragms.

In the above embodiment, two shutter blades are connected by a drive arm and moved in opposite directions, but as shown in FIG. 11, a rack 17 is provided on a part of each blade, and is fixed to the motor shaft. Exactly the same effect can be obtained by meshing with the pinion 16 and moving it straight by rotation of the motor.

(Effects of the Invention) As described above, the present invention provides two multipurpose shutter blades with two aperture holes of different shapes, and the overlapping holes change depending on the rotational direction of the pulse drive motor. However, by making it possible to obtain a large number of different numbers, the upper limit of the shutter speed determined by the frequency response limit of the pulse motor has been improved. However, it is also effective to incorporate a program for telephoto shooting by increasing the upper limit of the shutter speed by about twice, or by increasing the speed of the shutter especially at a wide open position.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a conventional example, Fig. 2 is an explanatory view showing the relationship between the rotation angle of the motor and the number in the conventional example, Fig. 3 is a perspective view showing an embodiment of the present invention, and Fig. 4 is an explanatory diagram showing the relationship between the rotation of the motor and the shutter speed in the same embodiment, FIG. 5 is a diagram showing the relationship between the conventional number and the shutter speed, and FIG. 6 is the aperture and shutter speed in the present invention. 7 is a plan view of the blade showing another embodiment, FIG. 8 is an explanatory diagram showing the relationship between the rotation angle of the motor and the diaphragm in the same embodiment, and FIG. FIG. 10 is a program diagram in this embodiment, and FIG. 11 is a plan view showing another embodiment. 1...Pulse motor 2...Drive lever 4.5...Shutter blade 6.7.8...Aperture hole 16...Pinion 17...Rack □ Applicant Canon Co., Ltd. No. 1 Figure 2'' Figure 53 Lender Z Roll 5 Figure Dry Stone Figure qI￥l Collection/ρ Figure

Claims (1)

[Claims] Two multi-purpose sheets, each with an aperture hole, driven by a pulse motor and moved stepwise in opposite directions according to the number of pulses, determining the exposure aperture based on the overlapping amount of the multiple holes. A pulse-driven shutter characterized in that each of the shutter blades 1/C1 is provided with two multi-holes having different shapes, and the combination of the overlapping multi-holes is changed depending on the rotating direction of the pulse motor.