JPS58190929A - Stop-down device of automatic iris - Google Patents

Abstract

PURPOSE:To apply the attracting force only at a place near the full-close position and to reduce the power consumption, by setting properly the form, size and position of a soft magnetic iron member which coacts with a movable magnet and adding an energy storing element to apply an aperture blade full-close current to a control circuit. CONSTITUTION:An energy storing element (capacitor) C is charged with connection of a main power supply S, and the proper aperture value is held with the control of a driving motor 4' and in response to the luminance information signal B. When the power supply is cut off, a switching circuit SW is turned on. Then the output of an operational amplifier P1 is reduced by the discharge of the capacitor C, and the aperture blade is stopped down to the full-close position. While the form and the size of a soft magnetic iron member 11 as well as its relative position to a rotary magnet 7 which moves the aperture blade are set respectively so that the attracting force that is generated by the magnet 7 only when the aperture blade is actuated at a place near the full-close position can actuate the aperture blade in the stop-down direction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a 9-diaphragm cutting device for an auto iris.

The auto iris is an automatic aperture device in cameras and video cameras that always operates to give the proper exposure to the film or image pickup tube depending on the brightness of the field, but when it is not in operation, it reliably keeps the nine diaphragm blades in the fully closed position. However, there is a need to prevent film exposure or damage to the image pickup tube should a cine or video camera be unintentionally pointed at an intense light source such as the sun.

For example, the auto iris shown in Fig. 1↓ and Fig. 2
As shown in the figure, it has been proposed to use a spring to hold the throttle in the fully closed position. In such an auto iris, a circular arc 1a provided on the non-magnetic diaphragm blade l is pivotally supported by a pin 2b planted in the diaphragm base plate 2 having an opening 2a. Known diaphragm D is rotatably supported. It is slidably supported by a pin 3a implanted in an IJ ring 3, and the direction in which the diaphragm blades 1 are opened when the diaphragm ring is rotated clockwise in FIG. When the aperture ring 3 is rotated counterclockwise, the diaphragm 9 blades 1 are swung in a direction in which the diaphragm 9 blades 1 are closed. A drive motor 4 is provided for operation between the closed position and the fully open position, and the drive motor 4 is mounted on a rotating shaft 6 within a non-magnetic coil support frame 5 as shown in FIGS. A rotating magnet 7 rotatably supported and wound around a coil support frame 5,
It consists of a drive coil 8 that is electromagnetically coupled to the rotating magnet 7, and a bolt case 9 that is fitted on the outside of the coil support frame 5 to form a magnetic circuit with the rotating magnet 7, and the drive coil 8 is energized. The rotating magnet 7 is electromagnetically rotated. An operating frame 7a is integrally attached to the rotating magnet 7, and this operating frame 7a is slidably fitted into a long groove 3C formed in the operating arm 3b of the aperture sill 3.
When the drive coil 81r is energized to rotate the 0-rotation magnet 7 counterclockwise in FIG. 1, the diaphragm ring 3 is rotated clockwise and the diaphragm blade 1 is swung toward the fully open position.
On the other hand, when the drive coil 8 is energized to rotate the rotating magnet 7 clockwise, the aperture ring 3 is rotated counterclockwise and the aperture blades are swung toward the fully closed position by the control circuit described below. The drive coil 8 is energized to face the diaphragm 9 aperture that provides appropriate exposure according to the brightness of the field, and the rotating magnet 7 is rotated to operate the diaphragm 9 blades 1. When the appropriate exposure is obtained, the drive coil 8 8's support will be stopped.

As mentioned above, in order to prevent the diaphragm blades 1 from being opened unintentionally and damaging the film or image pickup tube, the 9 diaphragm blades 1 are automatically fully closed when the control circuit is deenergized. For example, a tension spring 10 is tensioned between the actuating arm 3b of the diaphragm D IJ ring 3 and the main plate 2 to hold the diaphragm D in position.
The IJ ring is energized counterclockwise, and when the drive motor 4 is deenergized, the aperture blades 1 are always moved to the fully closed position and held there. Differently, an auto iris has also been proposed in which a soft magnetic iron member is disposed on the coil support frame to work with a rotating magnet to hold the nine diaphragm blades in the fully closed position. This is shown in FIGS. 5 to 7.

In FIG. 5, the overall configuration is similar to that shown in FIG. 1, but unlike the one in FIG. ll' spring 1
0 is omitted. And instead of such a spring there is a drive motor in FIGS. 1 to 4.

- Coil support frame 5 of drive motor 4' corresponding to motor 4
A pair of soft magnetic iron members 11 cooperate with the rotating magnet 7.

11 are arranged in symmetrical positions, and the attractive force generated by the rotating magnet 7 drives the rotating magnet 7 to rotate so as to move the aperture blade 1 to the fully closed position.

Necessary to drive the nine aperture blades to obtain proper exposure in the auto iris using a spring as described above, and to energize the drive motor to move and hold the aperture blades in the fully closed position when the aperture blades are not in operation. The current consumption is as per curve a shown in FIG. In Fig. 8, the horizontal axis shows the displacement of the diaphragm blades, and the origin is at the fully open position, and the diaphragm 9 moves toward the right.
When the blade is opened, the right end of n1 indicates the fully open position, and the vertical axis indicates the current consumption value.

The current consumption value shown by curve a is the amount of current that is generated when these members are moved against the resistance force due to the frictional force of the members that are relatively moved when moving the diaphragm blades when there is no tension spring. The basic operating current curve that must be applied to the drive coil in order to make it move shows that the tension spring is set to have a force that allows the nine blades of the diaphragm to be brought to the fully closed position from any position when inactive. It is the sum of the spring acting force versus load current curve C that must be supplied to the drive coil to produce the torque required to move the diaphragm blades to the fully open position against the acting force, which is a well-known throughput curve. The action force of the tension spring must be greater than the resistance force in the fully closed position so that the aperture blades can move the various members against the above-mentioned resistance force due to frictional force, etc., so that the spring action in the fully closed position is The load current against the force must be larger than the basic operating current at the corresponding position, and as the nine diaphragm blades are opened toward the fully open position, the tension spring's extension (n) and its acting force (Q) increase proportionally. Therefore, the spring acting force opposing load current also becomes proportionally thicker toward the fully open position, and therefore the current consumption curve a, which is the sum of the curves A and C, becomes significantly large.

In addition, even in an auto iris using a soft magnetic iron member, as shown in FIG. The attraction force vs. load current curve C' that needs to be supplied to the drive coil to generate the torque to fully open the nine diaphragm blades against the attraction force of the soft magnetic iron member to squeeze the diaphragm into the closed position. It is Japanese. In this case, the attraction force is strongest in the fully closed position where the soft magnetic iron member is close to the poles of the rotating magnet, and as the diaphragm blades are opened, the distance between them increases and the attraction force decreases rapidly. However, the suction force is at its minimum at the fully open position, but in order to be able to squeeze the diaphragm blades to the fully closed position even in this position, the suction force that also produces a large acting force due to resistance such as C) frictional force. In order to counter this, the aperture 9
Since a load current against the attraction force is required to be supplied to the drive coil to generate the torque to open the blades, the load current against the attraction force becomes significantly large in the fully closed position, and therefore the current consumption curve a' becomes significantly large. However, as is well known, cine cameras and video cameras with built-in auto iris are required to be more and more compact in recent years, and the power supply battery needs to be extremely small and have a small capacity, so the current consumption required for auto iris operation is reduced. tends to be limited to a minimum.

In view of the above, the present invention has a simple structure, reliable operation,
Moreover, it is an object of the present invention to provide an aperture cutting device for an auto iris that minimizes the required current consumption.

The diaphragm cutting device in the auto iris of the present invention is of a type that uses the above-mentioned soft magnetic iron member, and includes a non-magnetic diaphragm blade, a non-magnetic diaphragm blade actuating member interlocked with nine diaphragm blades, and a diaphragm blade actuating member. A movable foundation stone interlocked with the movable magnet is electromagnetically coupled to the movable magnet, and is energized to drive the movable magnet to move the aperture blades to a fully closed position and a fully open position via an aperture blade actuating member. a control circuit that energizes the drive coil to operate the aperture blades to an appropriate exposure aperture aperture according to field brightness; a power supply; and a support frame for the drive coil. In the aperture cutting device for an auto iris, the control circuit comprises a soft magnetic iron member that is magnetically coupled to the movable magnet and generates an attractive force by the movable magnet so as to operate the nine aperture blades to a fully closed position. A power storage element is provided which energizes the drive coil so as to operate the diaphragm blades to a substantially fully closed position when the power is cut off, regardless of the diaphragm opening position of the diaphragm blades. The attractive force generated by the movable magnet can actively move the diaphragm blades in the narrowing direction only when the 9 diaphragm blades are operated to a substantially fully open position in terms of shape, size, and relative arrangement position with respect to the movable magnet. It is characterized by being determined to be competent.

With this configuration, the current consumption is basically limited to the range in which the 9 diaphragm blades can be moved in the diaphragm closing direction against the resistance force when the 9 diaphragm blades are moved by the attractive force of the soft magnetic iron member near the fully closed position. The operating current is only increased, and in other ranges there is no attractive force that can move the 9 blades of the diaphragm, so the current consumption value is essentially only the basic operating current value 9. The current consumption is reduced to the minimum. This makes it possible to do so.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

The construction of the illustrated embodiment of the autoiris according to the invention is substantially similar to that shown in FIGS. 5-7.

In the present invention, as shown in FIG. 10, the control circuit is provided with an energy storage element, that is, a capacitor 〇, which energizes the drive coil so that the nine blades of the diaphragm can be moved to the fully closed position when the power is cut off. By appropriately setting the shape, dimensions, and arrangement position of the cooperating soft magnetic iron members in relation to the rotary magnet, the diaphragm is activated only when the nine diaphragm blades have substantially reached the fully closed position, as shown in FIG. A suction force is generated that can move the diaphragm blades in the closing direction against the resistance force when moving the 9 blades, and the 9 diaphragm blades are moved from the fully closed position to the open direction.
At times, the suction force is reduced so that the nine blades of the diaphragm cannot be moved.

The control circuit according to the present invention shown in FIG.
A dividing resistor R connected in series with the main power supply so as to generate
1+ R2, the reference voltage Vref', and the field brightness information signal B are compared. When the aperture is smaller than the appropriate exposure aperture value, the drive coil 8. A differential amplifier A including a 7'CI pair of operational amplifiers OP and OF2 connected to deenergize the drive coil 8 when the first aperture blade reaches the appropriate exposure aperture value; A diode D is connected in the forward direction to the main power supply S, and the diode D is in an OFF state when the main power supply S is energized, and is switched ON when the main power supply S is cut off. A switching circuit t is connected between the output side of the camera and the field brightness information signal input section B, and is configured to maintain the aperture blades at an appropriate exposure aperture value in accordance with the field brightness information signal B. It has become.

In this case, when the field brightness information signal B is higher than the reference voltages Vre and f, the output of the operational amplifier OPI decreases, and the output of the operational amplifier OP2 increases, driving the nine diaphragm blades in the direction of narrowing down. The coil 8 is energized, and in the opposite case to the above, the coil 8 is energized in the opposite direction.

According to the feature of the present invention, a capacitor C is connected to the main power supply S in parallel with the dividing resistors R1+R2.

Since the configuration is as described above, while the main power source S is connected and the auto iris is operating to maintain a proper exposure state, the capacitor C is in a charged state and the switching circuit y is in an OFF state. When the main power supply S is cut off and the auto iris is deenergized, the switching circuit SW
fl Switching circuit S in which current is ON from capacitor C which is switched ON and charged
It is input to the inverting input terminal of the operational amplifier OP1 via W, thereby reducing the output of the operational amplifier OPI and narrowing down the aperture blades. In addition to the drive coil 8, a brake coil 12 is provided in the control circuit shown in FIG. 1O, and its terminal is connected to the field brightness information signal input section B. and the operational amplifier OP as shown in the figure, and the electromotive force when the drive motor 4 is activated is transmitted to the differential amplifier A.
by connecting the differential amplifier in the direction of decreasing the return resistance Rs.
The shape, dimensions, and relative arrangement position of the soft magnetic iron member 11 to the rotating magnet 7 according to the present invention are shown in FIG. 11. A load current curve C in which the load current value against the attraction force is greatly reduced so that an attraction force that moves the aperture blades in the closing direction is generated only when the aperture blades are substantially in the fully closed position. is set so that 0 is obtained.
In other words, when the diaphragm blades are moved in the opening direction, the attraction force is much smaller than the value that would allow the diaphragm blades to move against the resistance force due to frictional force, etc., and the load current required to counter the attraction force is almost zero. It is possible to do so.

As described above, according to the present invention, the shape, dimensions, and location of the soft magnetic iron member that cooperates with the rotating magnet are appropriately set, and a current is supplied to the control circuit to return the aperture blades to the fully closed position when the power is cut off. By simply providing an energy storage element that can provide energy, it is sufficient to energize the drive coil with only a current that generates enough torque to overcome the motion resistance force of the aperture blades, with virtually no attraction force up to the fully closed position. Since the suction force can be applied only at the fully closed position, the current consumption can be significantly reduced.

In addition, when actually manufacturing the auto iris, for safety reasons, the 9-closed end position is set with enough margin to allow the 9 blades to be narrowed down a little further than the fully closed position of the diaphragm blades, and the suction force is set at this final position. The soft magnetic iron member is determined by the position between the substantially fully closed position and the slightly open position for safety, and the capacitance of the capacitor, which is the energy storage element, causes the aperture blades to only have the above resistance force. In contrast to the substantially fully closed position negative or slightly narrower than this for stability @
In addition, any of the connecting terminals of the drive coil can be used as the soft magnetic iron member, which reduces the number of required parts, and
When a separate soft magnetic iron member is provided, its shape and size and placement position can be set arbitrarily, and the best performance can be obtained.
Although the technical idea of the present invention is not limited to this example, a linear motor-type drive motor with linear operation is used, and the linear-operation throttling mechanism is suitably replaced with the above-mentioned rotary type. It can be used in any combination with the structure, and all of these modified forms are included in the present invention.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of an auto iris using a conventional tension spring. Figure 2 is a side view of Figure 1, and Figure 3 is a plan view of the drive motor used in the auto iris of Figure 1. FIG. 4 is a sectional view of FIG. 3. FIG. 8g5 is a plan view showing an example of an auto iris into which the present invention can be incorporated, which utilizes the attraction force of a soft magnetic iron member. FIG. 6 is a plan view of a drive motor used in the auto iris of FIG. 5 and into which the present invention can be incorporated. FIG. 7 is a sectional view of FIG. 6. FIG. 8 is a required current consumption characteristic curve diagram of the auto iris shown in FIG. FIG. 9 is a required current consumption characteristic curve diagram of the conventional auto iris of the type shown in FIG. FIG. 1O is a control circuit diagram according to the present invention. FIG. 11 is a required current consumption characteristic curve diagram of an auto iris incorporating the present invention of the type shown in FIG. １・・・・・・・・・・・・Aperture 9 blades 3・・・
......Aperture 9 rings 4.4'...
・・・・Drive motor 7・・・・・・・・・・・・・・・
・Rotating magnet 8-1・・・・・・・・・・・Drive coil 9・・・・・・・・・・・・・Iron case 11・・・
......Soft magnetic iron member 12...
・・・Brake coil A・・・・・・・・・・・・・・・
Differential amplifier B...... Field brightness information signal input section C...... Capacitor D...・・・・・・・・・Diode OPI + OF2 + OPs・・・Operation amplifier R
1+ R2+ Rs...Resistance Rref...Reference voltage S...
・・・・・・・・・・Main power switch・・・・・・・・・・
・・Switching circuit v11wILy'> Engraving (inside W+
=115tL) Figure 3 Figure 4 Figure 11 Procedural amendment June 7, 1981 Haruki Shimada, Commissioner of the Patent Office 1, ! JS I 11 Table of Contents 1982 Patent Application No. 07399θ2, 8 scoops of invention. Relationship between diaphragm cutting device 3 in auto iris and correction consideration 1'r Patent applicant's office: 16th, 2-chome, Shimura, Itabashi-ku, Tokyo, Inc. (Name) (In) Co., Ltd.: 2 A
71/Procedural Amendment June 1811 Commissioner of the Patent Office Haruki Shimada 1, Letter e1 Display Patent Application No. 073996 1988 2, Invention 2nd Name Aperture Cutting Device 3 in Auto Iris, Person Making Amendment Case Relationship Patent applicant address: 2-16-20 Shimura, Itabashi-ku, Tokyo
Cup (Name) (122) Co Pal Co., Ltd. (1
) "Round hole 1a" on page 5 of the specification, line 4, arc 1α
Corrected. (2) In the first line of page 6, "rotatable by a rotary shaft 6" was corrected to "rotatably arranged and integrally attached by a rotary shaft 6." (3) Figures 1, 2, 5, 10 and 11
The figures have been corrected to match the attached drawings. 7. Attached document drawing 1 copy

Claims (4)

[Claims] (1) 9 non-magnetic diaphragm blades, 9 diaphragm blades (ttc), 4 moving non-magnetic diaphragm blade actuating members, a movable magnet that interlocks with the diaphragm blades (/l = moving member, and is electromagnetically coupled to the movable magnet and energized) J: 9 movable magnet? Drive filter that operates the aperture blades between the fully closed position and the full position through the aperture blade operating member, and the aperture blades depending on the brightness of the field. A control circuit that energizes the drive coil to operate the exposure aperture to an appropriate aperture, a power source, and an I disposed on a support frame for the drive coil.
L, the aperture cutting device for an auto iris having a soft magnetic iron member that is magnetically coupled to the arsenic stone and generates an attractive force by a movable magnet so as to operate the aperture blades to a fully open position; is provided with an energy storage element that energizes the drive coil so that the aperture blades are operated to a substantially fully closed position when the power is cut off regardless of the aperture opening position of the aperture blades, and the soft magnetic iron member The shape, dimensions, and position relative to the movable magnet are such that the attractive force generated by the movable magnet will cause the aperture blades to actively move in the υ closing direction only when the nine aperture blades are operated to the fully open position. 'J'
``Aperture cutting device for auto iris with J signature. (2) The nine diaphragm blades have a margin operation end position in a direction in which the diaphragm blades are slightly narrowed down from the fully open position 14, and the capacity of the energy storage element is such that the diaphragm blades are operated to a substantially fully closed position when the power is cut off. The shape, dimensions, and arrangement position of the soft magnetic iron member are such that the attractive force of the movable magnet moves the nine diaphragm blades toward the end position of the margin operation just before the diaphragm blades are operated to the fully closed position. A diaphragm device in an auto iris according to claim 1 (1λ), which is defined to have the ability to (3) The 9-blade diaphragm operating member is configured to operate the diaphragm, and the movable magnet is a rotating magnet, which is rotatably disposed concentrically within the drive coil. A focusing device in an auto iris according to item 12 or item (2). (4) a differential amplifier that energizes a drive coil so that the control circuit compares the field brightness information voltage with a reference voltage and operates the nine aperture blades to an appropriate exposure aperture aperture position; The diaphragm cutting device for an auto iris according to any one of claims 1 to 3, comprising a braking coil that controls the output of the diaphragm and applies a braking action to the operation of the nine diaphragm blades.