JP2573997Y2 - Camera shutter opening and closing mechanism - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shutter opening / closing mechanism for a camera shutter.

[0002]

2. Description of the Related Art As an example of a camera shutter, the present applicant has disclosed Japanese Utility Model Application No. 2-32788 (Japanese Utility Model Application Laid-Open No. 3-125337).
Japanese Patent Application Publication No. The structure of this device will be described with reference to FIG. In the drawing, reference numeral 1 denotes a ring-shaped driving member having a cam surface 1a, a tooth portion 1b, and a bent portion 1c and rotatably mounted around an optical axis.
A blade opening / closing lever pivotally mounted thereon and having a fork portion 2b and a projection 2a abutting on the cam surface 1a of the driving member 1;
Reference numeral 3 denotes a spring for imparting a left-turning property to the blade opening / closing lever 2, and 4 is mounted on the back surface of the shutter substrate P so as to be rotatable concentrically with the driving member 1 and fitted to the fork portion 2 b of the blade opening / closing lever 2. Pin 4a (shutter substrate P
And a shutter blade 5 which is pivotally mounted on the back surface of the shutter substrate P and is pin-slot-connected to the blade opening / closing ring 4. Although only one sheet is shown in the drawing, the sheet is usually composed of five sheets and covers an exposure opening formed in the shutter substrate P at the illustrated position.

Reference numeral 6 denotes a pinion pivotally mounted on the shutter substrate P and meshed with the teeth 1b of the driving member 1, 7 denotes a gear integrated with the pinion 6, and 8 denotes a driving source mounted on the shutter substrate P. For example, a two-phase stepping motor. Reference numeral 9 denotes a drive gear fixed to the output shaft of the stepping motor 8 and meshed with the gear 7.
Reference numeral 10 denotes a pawl lever which is pivotally mounted on the driving member 1 and has a pawl 10a which can face the cam surface 1a, and its left-handed rotation is suppressed by the bent portion 1c. It is a spring that urges in the direction.

This mechanism has the above-described configuration,
Next, the opening and closing operation of the shutter blades in the normal shooting mode will be described. When a required number of shutter blade opening pulse signals are output during photographing based on the exposure amount set by the photometry, the stepping motor 8 is driven in the blade opening direction in accordance with the number of pulse signals. Then, at the time of the opening operation, the driving member 1 is turned clockwise via the driving gear 9, the gear 7 and the pinion 6, and the projection 2 a of the blade opening / closing lever 2 is moved from the top surface of the cam surface 1 a of the driving member 1 to the top of the claw lever 10. By sliding on the top and passing the tip, the spring 3
With the elasticity of the blade, the blade opening / closing lever 2 rapidly turns left. Since the drive ring 4 rotates clockwise in conjunction with this, the shutter blade 5 is opened.

[0005] At the time of closing operation from the fully opened state is performed after a lapse of time of predetermined seconds, since the stepping motor 8 is inputted pulse signal vane closure is reversely rotated, the vane opening lever 2 projections 2a are left-handed contact is pushed up by the cam surface 1a of the drive member 1 to, and thereby Tsumere
Since the bar 10 is returned to the position shown in FIG. 2 by turning clockwise, the shutter blade 5 is also moved to the closed position in conjunction with this.

The shutter opening / closing operation will be further described with reference to the sequence diagram of FIG. 3. In the stepping motor 8, the number of coils necessary for the one-phase MS1 (A) and the two-phase MS2 (B) of the stator winding required for the full-opening operation of the blades are determined. When a unit pulse is input, the shutter opening starts to open due to the release of the locking of the blade opening / closing lever 2, and exposure is started, and the shutter opening reaches a fully opened state. Thereafter, when a pulse signal for closing the blade is input after a lapse of the set predetermined time, the stepping motor 8 reversely rotates,
After a lapse of the mechanical delay of the opening / closing mechanism, the shutter blade is rapidly closed.

In such a shutter blade opening / closing mechanism, the pulse width of a plurality of pulse signals input to the stepping motor 8 during the blade opening operation is the same for each pulse, or the pulse time is shortened. Acceleration type is used. Therefore, especially in the small aperture region, unit pulses are output in a number corresponding to the opening waveform, and a pulse signal for closing the blade is output after a predetermined time has elapsed, so that the stepping motor 8 rotates in the reverse direction.

[0008]

However, in this case, since the driving speed of the stepping motor 8 at the time of the blade opening operation is high, the inertia of the stepping motor 8 or the driving member 1 in the opening direction is reduced when performing the closing operation by reversing. This is a major factor of the mechanical delay at the time of the small aperture, and the start of the closing operation is delayed, so that there is a problem that the shutter speed is reduced and it is difficult to increase the speed. In the case of the acceleration type in which the pulse time during the opening operation is shortened, the inertia also becomes large, and this problem is particularly serious.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a camera shutter opening / closing mechanism capable of increasing the shutter speed particularly at a small aperture with a simple configuration.

[0010]

According to the present invention, there is provided a camera shutter opening / closing mechanism in which a stepping motor is used as a drive source , and an opening / closing member interlocked with the stepping motor is reciprocated to open / close a shutter blade. in the pulse width of the last signal of the motor drive pulse signal for the shutter opening operation, by slightly longer than the pulse width of the previous signal, it is characterized in that so as to speed up the shutter speed Things.

[0011]

[Function] When the aperture waveform set at the time of shooting is a small aperture,
Since by lengthening the pulse width of the last pulse signal input to the stepping motor to the blade opening operation, the driving speed of the stepping motor of that portion is slow, even slower opening operation speed of the driving rotary members, open Direction shutter
The operating speed of the blade is slowed down, but the inertia acting in the opening direction when the operating direction is reversed in the closing direction is reduced accordingly,
Since the starting point of the closing operation is earlier, the overall shutter speed is increased.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 1. The shutter opening / closing mechanism is the same as the prior art shown in FIG.
Is the same. Therefore, detailed description is omitted. The sequence diagram of FIG. 1 shows a driving pulse signal for the blade opening / closing operation, which is input to one-phase MS1 (A) and two-phase MS2 (B) of the coil of the stepping motor 8. If the unit time, which is the pulse width of this pulse signal, is t [ms],
When opening the waveform set by photometry of small aperture area, two
The pulse time (pulse width) of the last pulse signal of the plurality of pulse signals for the opening operation input to the phase MS2 (B) is set to x [ms] larger than t. Here, it is preferable that the pulse time x be set within about 1.5 times the pulse time t (depending on the configuration of the shutter mechanism). 1.
If it exceeds about five times, the blade opening operation time becomes too long, and the overall shutter speed becomes slower than the conventional shutter speed, or the unevenness of the shutter is increased. For example, when the normal pulse time t is set to 3 [ms], the pulse time x may be set within a range of about 3 <x <4.5 [ms].

Since the present embodiment is configured as described above, the pulse signal input to the stepping motor 8 for the blade opening operation at the time of photographing with a small aperture is a two-phase M signal.
Since the last pulse signal input to S2 (B) has a time x longer than the time t of the other pulse signals, the rotation speed of the stepping motor 8 decreases by this pulse area near the top of the opening waveform. . Therefore, the gears 9, 7, 6
Is also decelerated.

Then, at a predetermined time (TAE in FIG. 1)
At the time of electrical control determined according to the shutter speed
while. Usually, to distinguish from the shutter speed (exposure time)
It is also called the time of the electric second. After the lapse of time, when a pulse signal for the blade closing operation is input to the stepping motor 8, the motor 8 rotates in the reverse direction, and the members such as the driving member 1 and the blade opening / closing lever 2 also move from the opening operation to the closing operation. Is reversed, but the inertia in the opening operation direction at this time is small.
Therefore, the mechanical delay is small, and the shutter blade 5 quickly closes. As described above, the opening operation of the shutter blade 5 is slightly slower than that of the conventional mechanism, but the mechanical delay is reduced and the starting point of the closing operation is earlier . Therefore, the opening waveform of the shutter at the time of the small aperture is shown in FIG. 3 shows a solid line as compared with the conventional one shown by a broken line. Therefore, the shutter speed as a whole is increased.

[0015] As described above, the present embodiment operates with the shutter open.
The last input to the stepping motor 8
By setting the pulse signal to have a longer pulse width than the other pulse signals, the inertia at the end of the opening operation can be reduced, and the shutter speed can be made higher than the conventional one.

The present invention is not limited to the above-described type of shutter opening / closing mechanism, but can be applied to all shutter opening / closing mechanisms operated by a stepping motor.
Needless to say, the stepping motor is not necessarily limited to the two-phase winding structure.

[0017]

As described above, the opening / closing mechanism of the camera shutter according to the present invention has a step for opening the shutter.
Since the pulse width of the last pulse signal input to the ping motor is set long, the shutter speed can be increased with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a shutter opening / closing operation sequence of a shutter opening / closing mechanism according to the present invention.

FIG. 2 is a schematic front view of a camera shutter opening / closing mechanism according to the prior art.

FIG. 3 is a diagram showing an operation sequence of the shutter opening / closing mechanism of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Driving member 2 Blade opening / closing lever 5 Shutter blade 8 Stepping motor

Claims (1)

(57) [Scope of request for utility model registration] 1. A stepping motor as a driving source, it
The closing member interlocked by reciprocated at camera shutter opening and closing mechanism which is adapted to open and close operation of the shutter blade, the last of the stepping motor <br/> over motor drive pulse signal for the shutter opening operation signals, other camera shutter closing mechanism slightly pulse width than the pulse signal is characterized by being set to be longer.