JPH0330130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that automatically controls exposure by opening and closing the shutter blade by controlling the operation of an electric drive source for opening and closing the shutter blade in accordance with subject brightness.

Conventionally, electric drive means for opening and closing the shutter blades include a method of driving an excitation wire ring in a uniform magnetic field, as seen in Utility Model Publication No. 46-24913, and a method of driving an excitation wire ring in a uniform magnetic field, as shown in Japanese Patent Publication No. 40-20145. A method of directly driving shutter blades electromagnetically,
Furthermore, driving means that are improved from those systems have been proposed.

However, since these drive means are designed to be lightweight in order to provide high-speed performance of the movable parts, there is a limit to the ability to obtain a large drive torque.

In addition, when the shutter blade is closed and the drive means is not energized, the electric locking torque does not work, so a separate locking mechanism is provided to mechanically lock the shutter blade and maintain the closed state. This has the disadvantage of complicating the process.

The present invention was made to improve these drawbacks,
This will be explained below with reference to the drawings.

FIG. 1 shows the structure of a drive source used in the automatic exposure control device of the present invention, in which a stator 3 having magnetic poles 1 and 2 and a stator 6 having magnetic poles 4 and 5 are arranged facing each other as shown. On the other hand, a rotor 7 consisting of a permanent magnet magnetized to four poles of N, S, N, and S was attached to the rotor 7 so as to be enclosed within the two stators 3 and 6. The rotating shafts 8 and 9 are connected to the stator 3,
The rotor 7 is inserted into the bearings 10 and 11 having through holes in the rotor 6 to fix the rotor 7 on the central shaft.

Furthermore, a ring-shaped coil 14 is installed around the outer periphery of the stators 3 and 6.
By arranging these, the driving source is completed as shown in FIG. 1B.

Next, the operation will be explained with reference to FIG.

The shaded magnetic poles N of the rotor 15 in the figure are provided to make it easier to understand the rotational movement of the rotor.

First, when current is applied to the ring-shaped coil 14, the magnetic poles 1 and 2 of the stator are magnetized to S poles and the magnetic poles 4 and 5 of stator 6 are magnetized to N poles, as shown in FIG. An attractive force acts between the poles and the rotor 7, which is magnetized in sections, and the rotor 7 is fixed at the illustrated position.

This state is the first step operation, and then the second step operation.
As a step operation, when the current direction of the ring-shaped coil 14 is reversed, the magnetic poles in the stators 3 and 6 become the first
The operation of the step is reversed and the state shown in FIG. It stops at the magnetically balanced position C in Figure 2, and as a result rotates 90 degrees from A to C.

Next, as a third step operation, when the ring-shaped coil 14 is energized again so that the magnetic poles 1, 2, 4, and 5 are in the state A, the magnetic poles in the stators 3 and 6 are in the state shown in Fig. 2 D. Then, a repulsive force acts on the rotor 7, causing the rotor 7 to rotate counterclockwise as shown by the arrow 16 in FIG. 2D and stop at the position shown in FIG.

As described above, the drive source of the present invention can control the rotational direction of the rotor 7 by controlling the direction of energization to the ring-shaped coil 14, and can perform clockwise and counterclockwise reciprocating motion at a rotation angle of 90 degrees. can be made to

The present invention uses this drive source to open and close an opening by a shutter blade, and FIG. 3 shows an embodiment of an exposure mechanism that combines the drive source and shutter blade.

The exposure mechanism includes a drive pin 1 on the rotation shaft 8 of the drive source.
8 and 19 are combined, and the sliding guide grooves 21 and 17 in the shutter blades 16 and 17 are connected to each other.
22 and driving pins 18 and 19 are slidably connected to each other.

The operation is such that when the rotor 7 of the drive source rotates and the rotating shaft 8 rotates, the drive pins 18 and 19 move in the direction of the arrow shown in FIG. Therefore, the shutter blades 16 and 17 are moved in the directions of arrows 41 and 42, respectively, and open the openings 23 and 2 provided in the shutter blades 16 and 17.
4, a fully opened opening 25 is obtained as shown in FIG.

Next, to close the opening 25, the rotor 7 is reversed and the drive pins 18, 19 are moved in the direction of the arrow, and the shutter blades 16, 17 are pulled back to the closed state shown in FIG.

Next, an apparatus of the present invention will be described in which the exposure mechanism is adapted to the brightness of the subject to obtain appropriate exposure.

In order to operate the exposure mechanism to obtain proper exposure, means for controlling the rotational direction of the drive source and means for controlling the exposure time in accordance with the brightness of the subject are required.

FIG. 4 shows an embodiment of means for controlling the rotational direction of the rotor of the drive source.

The structure is such that the rotor 7 is provided with a protrusion 26, one stator 6 is provided with locking protrusions 27 and 28, and the protrusion 2 is provided with a protrusion 26.
6 are locked with the locking protrusions 27 and 28 to lock the movement of the rotor 7, and the locking position changes from the state shown in FIG. 2B to the state shown in FIG. 2C, for example. When the locking protrusion 27 changes, the locking protrusion 27 moves the fifth position slightly to the left of the locking position shown in FIG.
The rotor 7 is configured to be locked at the position _a1 shown in FIG.

In such a configuration, when the rotor 7 is rotated in the counterclockwise direction of the arrow ₁₆ as shown in FIG. The twisting force acts to ensure reliable rotation in the counterclockwise direction.

Furthermore, if the locking position of the rotor 7 in the state shown in FIG. 2C is also configured to be locked at the position _a2 slightly shifted to the right as shown in FIG. 5B by the locking protrusion 28, Even when it is desired to rotate the arrow 12 clockwise, the clockwise rotation can be reliably performed in the same manner as described above.

In addition, the locking mechanism of the means for controlling the rotational direction of the stator is capable of absorbing the moment of inertia accompanying the rotation of the rotor 7 in a predetermined direction, and if there is no locking mechanism, the rotor 7 will be When the rotor rotates to the state shown in C, the moment of inertia given to the rotor 7 causes the rotor to overshoot the predetermined locking position, and then the rotor rotates again due to the attractive force with the stator. This results in a so-called excessive damping phenomenon in which the damping motion of the rotor alternately changes over a short period of time so that the child 7 moves in the opposite direction and then stops.

Such a damping phenomenon causes exposure errors when the shutter blades are opened and closed in response to the brightness of the subject, and when the aperture 25 is fully open, the exposure amount operates to increase or decrease following the damping phenomenon, impairing exposure accuracy. Furthermore, when closing, even if the opening is closed, it will open again, which poses the risk of large amounts of exposure.

However, by providing this locking mechanism, the moment of inertia of the drive source is mechanically absorbed to prevent the above-mentioned malfunction.

FIG. 6 shows an embodiment of an automatic exposure device that controls the above-mentioned exposure mechanism in accordance with the brightness of the subject.

In the figure, when the shutter button 29 is pressed, the switch 32 is shorted and the power supply 30 is connected to the control circuit 31.
is supplied to

When the power supply 30 is supplied, the transistor 33 becomes conductive due to the base current flowing through the resistors 34 and 35, while the base circuit is short-circuited by the transistor 37, which is conductive due to the base current flowing through the resistors 34 and 36, and becomes non-conductive. A current flows through the resistor 39 in the direction of the arrow 40 to the ring-shaped coil 14 connected between the transistor 38 and the transistor 38 in the state.

Assume that the current in the direction of arrow 40 causes the excitation shown in FIG. 2B and starts the clockwise rotation shown in FIG. 2C.
8 and 19 are rotated clockwise to move the shutter blades 16 and 17 in the directions of arrows 41 and 42, thereby changing the opening 25 to be fully open.

At the same time, as the shutter blade 16 is moved in the fully open direction, both ends of the integration capacitor 44, which is configured to open the separate integration start switch 43, are opened, and a photocurrent generated by the light receiving element 45 corresponds to the subject brightness. Start charging.

After that, the opening 25 formed by the shutter blades 16 and 17
Integrating capacitor 4 remains fully open.
When the charging voltage of transistor 4 reaches the base potential of transistor 46, transistor 46 becomes conductive and short-circuits the base circuit of transistor 33.
3 is in a non-conducting state.

On the other hand, the base and emitter of the transistor 37 are also short-circuited, and the transistor 37 becomes non-conductive. As a result, the base current can be supplied to the transistor 38 via the resistor 47, and the direction of current flow to the ring-shaped coil 14 is directed as indicated by the arrow 48. Reverse it in the direction shown.

Therefore, a driving torque in the counterclockwise direction as shown in FIG.
9 in the counterclockwise direction, the shutter blades 16,
17 is driven in the opposite direction to when fully opened, opening 25
is operated to close a predetermined opening.

The control circuit operates as described above, and its aperture time changes depending on the brightness of the subject, so that proper exposure can always be automatically obtained.

Moreover, since the drive means of the present invention uses the rotor 7 made of permanent magnets, the shutter blades 16, 17
After the shutter button 2 is closed, that is, after the state changes to the state shown in FIG.
Even if the rotor 9 is stopped when the rotor 9 returns, an attractive force acts between the magnetic poles of the permanent magnet in the rotor 7 and the magnetic poles of the non-excited stators 3 and 6, causing the rotor 7 to return to the state shown in Fig. 2 E. The shutter blades 16 and 17 can maintain the closed state without requiring a separate mechanical locking mechanism.

Further, in this embodiment, the rotation angle of the rotor is shown as 90 degrees, but the rotation angle of the rotor is not necessarily limited to this, and the number of poles of the stator and the number of magnetic poles of the rotor can be increased or decreased as necessary. Of course, it is possible to change the rotation angle and to design the shutter blade according to the rotation angle to obtain a desired exposure mechanism.

As described above, the automatic exposure device of the present invention uses a driving means composed of a rotor having a plurality of permanent magnetic poles and a plurality of poles excited by a single-phase excitation coil. By installing a locking mechanism that can be simplified and controls the rotational direction of the rotor and absorbs the mechanical moment of inertia, the damping phenomenon of the rotor is eliminated and malfunction of exposure is prevented.

Furthermore, the shutter blades can be reliably kept closed by the attractive force between the rotor and the stator when no current is applied, and it is possible to provide an apparatus having advantages such as being able to sufficiently withstand mechanical shocks.

[Brief explanation of the drawing]

1A and 1B are an exploded view and a completed assembled view of the drive source used in the automatic exposure device of the present invention, FIGS. 2A to 3E are explanatory diagrams of the operation of the drive source shown in FIG. -C show the exposure mechanism of the present invention which is formed by combining a drive source and a shutter blade, FIG. 4 shows a drawing in which a locking mechanism is applied to the drive source shown in FIG. 1, and FIG.
Figures A and B illustrate the operation of the drive source provided with the locking mechanism shown in Figure 4, and Figure 6 is a circuit diagram showing the automatic exposure device of the present invention. 1, 2, 4, 5...Magnetic pole, 3,6...Stator,
7...Rotor, 14...Ring-shaped coil, 16,
17... Shutter blade, 18, 19... Drive pin, 20... Drive member, 21, 22... Sliding guide, 23, 24, 25... Opening, 26, 27, 2
8... Locking protrusion, 30... Power supply, 31... Control circuit, 43... Switch contact.

Claims (1)

[Claims] 1. A rotor having a plurality of permanently magnetized poles in which adjacent poles are different from each other, and a rotor having a plurality of magnetic poles surrounding the rotor and having the same number of permanent magnetized poles as the plurality of permanently magnetized poles in the rotor. a stator, a drive source comprising a coil whose energization direction is switched and energized so that each of the plurality of magnetic poles of the stator is excited with a polarity different from that before the energization direction was switched;
A shutter blade mechanically connected to the rotor and opened and closed by clockwise rotation of the rotor, and a shutter blade that is opened and closed by rotation of the rotor in a counterclockwise direction; When the shutter blade rotates in a fully open direction, the rotation of the rotor is locked at a first locking position where the relative positions of the plurality of poles of the rotor and the plurality of magnetic poles of the stator are shifted. a first locking mechanism; energizing the coil in a second direction opposite to the first direction to excite the magnetic poles of the stator to a polarity different from that when the shutter blade is fully opened; A second structure in which the relative positions of the plurality of poles of the rotor and the plurality of magnetic poles of the stator are shifted when the child is rotated in the closing direction of the shutter blades.
a second locking mechanism that locks rotation of the rotor at the locking position; and a second locking mechanism that is turned on by pressing down the shutter button and energizes the coil in the first direction to move the rotor to the first locking position. a first switch circuit that rotates the shutter blade until the shutter blade is fully opened; a brightness detection circuit that is connected to the brightness detection circuit and detects the subject brightness when the shutter blade is fully opened; a second switch circuit that operates when the first switch circuit is turned off and turns off the first switch circuit; Rotate the third part until it reaches the locking position.
Automatic exposure control device consisting of a switch circuit.