JPH05119366A - Diaphragm controller for solid-state image pickup device - Google Patents

Abstract

PURPOSE:To execute diaphragm control for a solid-state image pickup device with simple constitution and with low power consumption. CONSTITUTION:A torsion coil spring (pressing means) 5 is fixed to a driving arm 4 whose one end is stuck to a 1st bottom board 1 and whose other end is stuck to the rotary shaft of a galvanometer. Thus, the pressing direction of the spring 5 is a CCW direction (diaphragm opening direction), and 1st and 2n stop blades 2 and 3 slide upward and downward, respectively, so that the diaphragm becomes open. In the case of stopping down, the driving arm 4 is driven in a CW direction (diaphragm closing direction) against the pressing force of the spring by the driving means of the galvanometer, thereby accomplishing stopping down.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm control device for a solid-state image pickup device, and more particularly to a diaphragm control device for a solid-state image pickup device in which current consumption is reduced.

[0002]

2. Description of the Related Art As is well known, in a solid-state image pickup device such as a video camera, a subject image is formed on a light receiving surface of an image pickup device through a desired optical system, and light is photoelectrically converted into an electric signal. As an image pickup device used here, an image pickup tube was used before, but in consumer video cameras in recent years, as user needs change to small size and low cost, C
Solid-state image pickup devices such as CDs are generally widely used.

On the other hand, in the diaphragm control device for the light quantity used in the video camera, the galvanometer is generally used for driving the diaphragm blades because the light quantity incident on the solid-state image pickup device is controlled to be constant as described later. ing.

As shown in FIG. 7, this galvanometer includes a rotor 44, a rotor 44 that holds the rotor 44 rotatably, and a drive coil 43a and a braking coil 45a that are wound so as to face the central axis of the rotor 44. , Each has first
And a second stator 45, and the rotor 44, various housings 42, 47 and 48 for packaging the respective stators 43 and 45, and the terminal plate 41 constitute a main part thereof, and rotate as necessary. A Hall element 46 for position detection is built in.

FIG. 8 is a schematic diagram for explaining the operation of the galvanometer. The upper part shows a state when cut by a plane perpendicular to the rotor center axis simply by the rotor 44 and the drive coil 43a. It is a state diagram. A current i is applied to the drive coil 43a, and a magnetic field B generated in the drive coil 43a generates magnetic poles N and S at the coil ends.
Thereupon, the rotor rotates due to attraction and repulsion with the magnetic poles magnetized in the rotor. This is shown in the lower diagram by a diagram in which the rotor rotation angles π / 4 are sequentially arranged side by side.

The lower diagram 23 shows the torque generated when electricity is applied as described above, with the horizontal axis representing the rotation angle (θ) of the rotor and the vertical axis representing the torque. At this time, the torque that causes rotation in the CW direction is (+), and the torque that causes rotation in the CCW direction is (-). As is clear from this figure, at the rotor positions of θ = −π, 0, π, it is understood that no torque that causes rotation is generated.

By the way, in the diaphragm control device for the light quantity, the rotation angle of the rotor is transmitted to the diaphragm blades by the drive member,
The exposure control is performed by the diaphragm blade entering the optical path up to a predetermined amount. Therefore, if the rotor angle that does not generate the torque is included in the rotor use range angle within the diaphragm blade drive range, the rotor becomes inoperable. Therefore, the range angle of the rotor is set to -π <θ <0 or 0 <θ.
It is set within the range of <π.

As described above, in rotating the rotor, the magnetic field generated from the energized drive coil,
Since the rotor rotates due to the relationship with the magnetized magnetic field of the rotor, when the rotor is energized from a rotor position other than θ = −π, 0, π, as shown in FIG. 7, when the rotor rotates up to θ = −π, 0, π. , I will stop there. Further, when the energization is stopped, a magnetic field is not generated from inside the drive coil, so the rotor does not try to rotate itself, but due to the structure, it easily rotates due to an external force.

Therefore, when the galvanometer is used as the drive actuator of the diaphragm control device for the amount of light, it does not have the ability to self-hold the stop position, so some kind of biasing means is required. In order to constantly control the amount of light incident on the solid-state image sensor according to the brightness of the subject image, a biasing unit that biases the rotor output in a direction opposite to that of the rotor output is provided to obtain an appropriate aperture opening area. As described above, it is necessary to drive the diaphragm blade via the drive transmission means.

As for the urging direction at this time, as disclosed in Japanese Utility Model Publication No. 60-20105, in order to protect the image pickup tube which is an image pickup element, the diaphragm blades are closed when the power is turned off. It was urged in the closing direction of the diaphragm to block the subject light.

FIG. 9 is a block diagram showing the electrical construction of a conventional aperture control device in a video camera, in which subject light is input to an image sensor 33 through a taking lens 31 and an aperture 32. Output signal of this image pickup device 33 (image pickup signal)
Is input to the brightness detection circuit 34 and is also sent to an image pickup system (not shown) for signal processing.

The brightness signal B detected by the brightness detection circuit 34 is input to the error amplification circuit 35, and the diaphragm reference signal A is input.
The difference between and is amplified. Then, the output signal C of the error amplification circuit 35 drives the galvanometer 40 via the drive circuit 36, and the diaphragm 32 opens and closes.

That is, the diaphragm 32 is set so that A = B, that is, the amount of light incident on the image pickup device 33 becomes a constant value.
The diaphragm 32 will be closed-loop controlled. in this case,
If the amount of incident light is insufficient even if the diaphragm 32 is fully open, A
However, the exposure level is controlled to be constant by increasing the gain in the imaging system. FIG. 10 is a circuit diagram showing the configuration of the error amplification circuit 35 and the drive circuit 36 in FIG. 9 described above. In this case, the diaphragm mechanism is
It is assumed that the spring is biased in the "closed" direction.

The error amplifying circuit 35 calculates the difference between the aperture reference signal A and the luminance signal B and amplifies the operational amplifier OP1.
And a fixed resistor R for setting the amplification factor of this amplifier OP1
1 and R2. The drive circuit 36 is
It is formed of an NPN transistor Q1 and controls the current I flowing through the drive coil 43a of the galvanometer 40 by the transistor Q1. The braking coil of the galvanometer 40 is omitted. In this case galvanometer 40
The rotor 44 stops at a position where the rotational force in the throttle opening direction generated by the current I and the spring force in the throttle closing direction are suspended.

In the conventional driving means having such a structure, when the brightness of the subject changes in the direction of darkening, for example, A> B, so that the level of the output terminal C of the operational amplifier OP1 rises. As a result, the current I increases and the rotor 44 of the galvanometer 40 rotates in the “opening” direction, and moves to a position where A = B, that is, a position where the incident light amount reaches a predetermined value.

Under a condition that the aperture is not fully opened and is brighter than a certain extent, the current I decreases and the rotor 44 rotates in the "closed" direction, so that the relation of A = B is maintained. At that time, the potential of the output terminal C of the operational amplifier OP1 (approximately equal to the voltage applied to the drive winding) is considerably lower than Vcc, for example (1 /
2) It is usually designed to generate a torque that suspends the spring force at about Vcc.

Next, under a dark condition above a certain level, for example, under the condition that the amount of incident light is not sufficient even when the diaphragm is fully opened, the relation of A> B is always established. As a result, the voltage at the output terminal C of the operational amplifier OP1 rises to the level of the power supply voltage Vcc, and a current approximately twice as large as the above condition of A = B continues to flow in the drive coil 43a.

[0018]

As described above, the structure is such that the aperture area of the diaphragm is changed and held by the suspension with the biasing means biased in the direction opposite to the rotor output. It is necessary to constantly energize the drive coil regardless of whether the brightness of the subject is constant or variable.

Further, in the above-mentioned light amount diaphragm control device, the friction between the diaphragm blades and the base plate is reduced, the unnecessary driving load is prevented by avoiding the contact between the diaphragm blades, and the force such as a spring as a biasing means is reduced. Various measures have been taken such as reduction of driving load due to the improvement of power saving. However, as described above, since it is necessary to always energize the drive coil at the time of use, it is not a decisive means for reducing the power consumption.

In particular, when shooting with the aperture fully opened, such as when shooting indoors or in the evening, a large current flows through the drive coil. This poses a serious problem in battery-powered small video cameras, for example.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a diaphragm control device for a solid-state image pickup device with a simple structure and low power consumption.

[0022]

A diaphragm control device for a solid-state image pickup device according to the present invention comprises a diaphragm member, a biasing means for biasing the diaphragm member so that the diaphragm is in an open state, and a biasing force of the biasing means. Drive means for driving the diaphragm member by using electrical energy against the above.

[0023]

In this diaphragm control device for a solid-state image pickup device, the diaphragm is normally set to the open state by the biasing means, and when the diaphragm is narrowed, the driving means resists the biasing force of the biasing means to move the diaphragm member. To drive.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. 2 and 3 are exploded perspective views of a mechanical mechanism of a diaphragm control device for a solid-state imaging device according to an embodiment of the present invention.
2 and the members related to the drive arm 4 are shown in FIG. 3, respectively. The symbols m1 to m7 are the same as those in FIGS.
It is a code indicating a connection relationship between the two.

In FIGS. 2 and 3, a first diaphragm blade 2 and a second diaphragm blade 3 serving as diaphragm members, which regulate the aperture opening amount, are provided between the first base plate 1 and the second base plate 51. , Is inserted so as to be vertically slidable on a plane perpendicular to the optical axis. The first diaphragm blade 2 and the second diaphragm blade 3
Although not shown in the drawing, the plurality of convex portions 1a provided on the first ground plate 1 at positions other than the light transmitting holes 1d and the second ground plate 51 at positions other than the light transmitting holes 51a are not shown. Due to the provided convex portion, each diaphragm blade does not touch,
It is held at an appropriate position on the optical axis.

The long holes 2a and 2b are formed in parallel with the right side edge of the first diaphragm blade 2 in the drawing.
One ends of the first guide pins 52a and 52b slidably fitted in the a and 2b are fixed to the first base plate 1 by press fitting, welding or adhesion. Then, the other end is supported by the second base plate 51.

A long hole 2c parallel to the upper edge of the first diaphragm blade 2 is formed above the long hole 2a, and a drive pin 4a of a drive arm 4 described later is slidably fitted therein. It is supposed to be done. A curved portion 2d having a partial arc shape is formed below the first diaphragm blade 2 to adjust the amount of transmitted light of the subject light in cooperation with the second diaphragm blade 3.

The long holes 3a and 3b are formed in parallel with the left side edge of the second diaphragm blade 3 in the drawing.
One ends of the second guide pins 53a and 53b slidably fitted in the a and 3b are fixed to the first main plate 1. Then, the other end is supported by the second base plate 51.

A slot 3c is formed above the slot 3a in parallel with the upper edge of the second diaphragm blade 3, and a drive pin 4b of a drive arm 4 described later is slidably fitted therein. It is supposed to be done. Further, below the second diaphragm blade 3, a curved portion 3d having a partial arc shape for adjusting the amount of transmitted light of the subject light is formed.

The first main plate 1 of the second main plate 51
To the first positioning pins 55a, 55
regulated by b, the first screws 54a, 54b, 54c
It is fixed by.

On the right side of the first main plate 1 in the figure, that is, on the CCD side, the aperture is set to open, so when the aperture control device in the figure is viewed from the object side to the CCD side, the CW direction (clockwise direction) is seen. The spring flange 6 for holding the torsion coil spring 5 charged in () is fixed to the main plate 1 by the spring fixing screw 57. Further, on the right side thereof, the galvanometer 40 as a diaphragm driving unit is provided with the second positioning pin 56.
through the second screw 58a, 58b through a, 56b,
It is fixed to the first main plate 1.

A drive arm 4 for transmitting the rotational force of the meter 40 to the first and second diaphragm blades 2 and 3 is fixed to the rotary shaft 40a of the galvanometer 40. A second spring receiver 4c is provided on the left side of the drive arm 4 in the drawing.
Are planted, and one end of the spring 5 is locked. The other end of the spring 5 is locked to a first spring receiver 1e provided above the first base plate 1.

The first drive pin 4a and the second drive pin 4b, which are provided upright at both ends of the drive arm 4, have openings formed near the upper edges of the first main plate 1. 1
The upper elongated hole 2c of the first diaphragm blade 2 and the upper elongated hole 3c of the second diaphragm blade 3 are engaged with each other through b and 1c.

FIG. 1 shows the first and the second via the drive arm 4 by the urging force of the torsion coil spring 5 in FIGS.
FIG. 4 is a front view of relevant parts when the CCD side is viewed from the object side in FIGS. 2 and 3 in order to explain the movement of the diaphragm blades 2 and 3.

One end of the spring 5 is attached to a second spring receiver 4c which is set up near the end of the drive arm 4 fixed to the rotary shaft 40a of the galvanometer 40, and the other end is attached to the first main plate 1. The first spring bearing 1e planted on the upper side edge of
Each is locked. The first and second drive pins 4a and 4b provided at both ends of the drive arm 4 are
The first and second diaphragm blades 2 and 3 are engaged with each other.

That is, the return coil spring 5 serves as an urging means for urging the diaphragm member so that the diaphragm is opened.
Further, the driving means for driving the diaphragm member using electric energy against the biasing force of the biasing means is the galvanometer 4 described above.
0, respectively.

In the aperture control device constructed as shown in FIGS. 1 to 3, the torsion coil spring 5 is charged in the CW direction shown in FIGS. 2 and 3, so that the urging force of the spring 5 is CCW shown in FIG. It acts in the direction (counterclockwise). Therefore, since the drive arm 4 rotates in the CCW direction, the first diaphragm blade 2 engaged with the drive pin 4a of the arm 4 is
The second aperture blade 3 which is guided straight through the long holes 2a and 2b and which is engaged with the drive pin 4b of the arm 4 in the upward direction perpendicular to the optical axis is straightly guided through the long holes 3a and 3b. Each slides in the downward direction perpendicular to the optical axis. At this time, the partial arc-shaped portion 2d of the first diaphragm blade 2 and the partial arc-shaped portion 3d of the second diaphragm blade 3 are formed so that the diaphragm aperture is maximized.

On the other hand, in the galvanometer 40, the rotor operating angle is set over the whole range from the fully closed to the fully opened so that the galvanometer 40 rotates in the CW direction when energized. At this time, the rotor working angle is set so as to avoid the rotor angular position where torque is not generated as described in the explanation of FIG.

Therefore, from the biasing direction of the torsion coil spring 5 and the rotating direction of the galvanometer 40 when the galvanometer 40 is energized, if the energization is not performed as described above, the iris opening becomes maximum according to the biasing force of the torsion coil spring 5 and the energization is performed. For example, the generated torque is determined by the amount of electricity and the angular position of the rotor.
If the generated torque and the biasing force generated by the torsion coil spring 5 are in balance, the throttle opening is controlled at the balanced rotor angular position. Further, from the above, the throttle opening is controlled so that if the torque generated by the galvanometer exceeds the biasing force of the torsion coil spring 5, the diaphragm opening becomes smaller, and conversely if it becomes lower, the diaphragm opening becomes larger.

FIG. 4 shows a tension coil spring 5 instead of the torsion coil spring 5 as a biasing member for biasing the drive arm 4.
In the example according to A, the spring urging direction by the coil spring 5A is the downward direction in the figure. The coil spring 5A has a pin 4A having one end planted in the drive arm 4 and a pin 1A having the other end planted in the first main plate 1.
It is a tension spring locked to each.

In FIGS. 1 to 4, the spring has been described as the biasing member in the "throttle opening" direction, but the present invention is not limited to this and may be a magnet or a rubber-like member. Further, two diaphragm blades that move up and down in the direction perpendicular to the optical axis have been described as diaphragm members for diaphragm control of subject light, but the present invention is not limited to this, and a large number of blades are slid in a ring shape. The present invention can also be applied to a so-called arrow wheel type in which the blades are moved, or a so-called scissor type in which two blades control an opening amount while drawing an arcuate locus in a plane perpendicular to the optical axis.

Next, a first embodiment of the diaphragm control device for a solid-state image pickup device according to the present invention constructed as described above will be described with reference to FIG. The difference between the first embodiment and the conventional example shown in FIG. 10 is that a PNP transistor Q2 is used instead of the NPN transistor Q1 as the drive circuit 36, and the emitter of the transistor Q2 is the galvanometer 40. The one end P2 of the drive coil 43a is connected to the coil 4
The other end P1 of 3a is connected to a terminal for applying the power supply voltage Vcc. Except for these points, there is no difference from the above-mentioned conventional example, so that the same reference numerals are given to the respective constituent members including the error amplification circuit 35, and the description thereof will be omitted. It is assumed that the diaphragm mechanism is biased by a spring or the like in the direction in which the diaphragm opens as described in FIGS.

In the thus constructed first embodiment, the direction of the current I flowing through the drive coil 43a is P1.
→ P2 is set and the direction is opposite to that of the conventional example.
The direction of the rotational force generated in 1 is also the "closing direction", which is the reverse of the conventional example.

Under a condition that the aperture is not fully opened and is bright to some extent, the subject brightness signal B is equal to the aperture reference signal A.
On the other hand, the voltage at the output terminal C of the operational amplifier OP1 is controlled so that A = B, and the current I flows through the drive coil 43a via the transistor Q2. The current I at this time generates a rotational force that balances the spring force, and has almost the same value as in the conventional example.

Under a condition where the light is dark to some extent, for example, the amount of incident light is not sufficient even when the diaphragm is fully opened, the relation of A> B is always established. As a result, the voltage at the output terminal C of the operational amplifier OP1 rises to about Vcc, and the transistor Q2 is turned off, so that it stabilizes at I = 0. That is, the diaphragm is fully opened only by the spring force.

That is, by connecting the PNP transistor Q2 as shown in FIG. 5, it is possible to configure a control means for minimizing the current flowing through the drive coil 43a when the diaphragm is opened. FIG. 6 shows an error amplifier circuit 35 and a drive circuit 36 in a diaphragm controller for a solid-state image pickup device according to a second embodiment of the present invention.
In the circuit diagram showing the outline of FIG. 10, the second embodiment is largely different from the conventional example shown in FIG. 10 in that the inverting input terminal and the non-inverting input terminal of the operational amplifier OP1 which is one of the components of the error amplifier circuit Since the diaphragm reference signal A and the luminance signal B applied to the end are applied in reverse, the potential of the output end C of the operational amplifier OP1 is opposite to that in the first embodiment, that is, If A> B, it becomes "L" level, and if A <B, it becomes "H" level. Therefore, the collector of the NPN transistor Q1 is connected to the power supply voltage Vcc, and the emitter is connected to the one end P1 of the drive coil 43a. The other end P2 of the coil 43a is grounded. Except for these points, there is no difference from the first embodiment described above, so the same components are assigned the same reference numerals and explanations thereof are omitted. Note that the diaphragm mechanism is biased by a spring or the like in the direction of opening the diaphragm, as in the first embodiment.

In the second embodiment thus constructed, the current I flowing through the drive coil 43a of the galvanometer 40 is directed in the same direction as in the first embodiment.
Since the direction is from the terminal P1 to the terminal P2, which is the reverse of the case of the conventional example, the direction of the rotational force generated in the rotor 44 is also the direction of "closed stop", which is the reverse of the conventional example.

Under the condition that the aperture is not fully opened and is bright to some extent, the voltage of the output terminal C of the operational amplifier OP1 is controlled so that the subject brightness signal B becomes A = B with respect to the aperture reference signal A. Then, the current I flows through the drive coil 43a via the transistor Q1.

Under a condition where the light is dark to some extent, for example, the amount of incident light is not sufficient even when the diaphragm is fully opened, the relationship of A> B always holds. As a result, the voltage of the output terminal C of the operational amplifier OP1 becomes substantially the ground level, and the transistor Q1
Is turned off, the drive current I becomes I = 0. That is, the diaphragm is fully opened only by the spring force.

That is, by connecting the NPN transistor Q1 as shown in FIG. 6, it is possible to configure a control means for minimizing the current flowing through the drive coil 43a when the diaphragm is opened. In the first and second embodiments, the direction of the rotational force of the galvanometer 40 is changed by changing the direction of the current I flowing through the drive winding. However, the galvanometer 40 has a rotation angle of 180 ° as shown in FIG. If it changes, the polarity of the torque changes. Therefore, the present invention can be realized even if the positional relationship between the rotor of the galvanometer and the drive arm is shifted by 180 ° from the conventional one without changing the energizing direction of the drive current.

According to each of the above-mentioned embodiments, it is possible to intermittently cut off the power supply to the galvanometer in order to control the light amount when the aperture control device for the light amount used in a video camera or the like is used.

In recent years, the minimum subject illuminance is always written in the specification column of the video camera product catalog, which shows that the user has a high demand for photographing a low-brightness subject and there are many photographing opportunities in such a place. ing. In shooting in a relatively dark place such as in a room, as the aperture control device for the light amount, the F-number near the open aperture, that is, a low FNo is often used. It can significantly contribute to the reduction of power consumption.

By the way, as described in the conventional example, the actual model number 60-
At the time of the invention of No. 20105, since an image pickup tube was widely used as an image pickup element, the photoelectric conversion film used for this was weak in physical properties, and thus strong light was applied for a long time. There is a so-called burning phenomenon that causes an irreversible change, and it was necessary to prevent this.

However, recently, as described above, a solid-state image pickup device such as a CCD has been widely used as an image pickup device, and since a silicon photodiode is used as a photoelectric conversion device, the phenomenon of burning actually occurs. Absent. Therefore, even if the power is forcibly turned off or turned off (for example, the main switch of the video camera main body is turned off), or the user carelessly points the video camera to the sunlight or a strong light source, the present invention With such a device, there is no risk of damaging the imaging unit.

In each of the above embodiments, the galvanometer is used as the diaphragm driving means, but the invention is not limited to this, and a DC motor, a stepping motor, an electromagnetic solenoid, a piezoelectric element or the like may be used. ..

[0056]

As described above, according to the present invention, the diaphragm member is normally urged by the urging means so that the diaphragm is opened, and when the diaphragm is squeezed, the urging force of the urging means is resisted. Further, since the diaphragm member is driven by the driving means utilizing electric energy, the remarkable effect that the power consumption can be reduced with a simple structure is exhibited.

[Brief description of drawings]

FIG. 1 is a front view of a main part in FIGS.

FIG. 2 is an exploded perspective view of a mechanical mechanism of the aperture control device for a solid-state imaging device according to the embodiment of the present invention, showing the components arranged between the first ground plate and the second ground plate. ..

FIG. 3 is an exploded perspective view of a mechanical mechanism of a diaphragm control device for a solid-state imaging device according to an embodiment of the present invention, showing a member related to a drive arm.

FIG. 4 is a front view of a main part showing another example of the biasing means in FIG.

FIG. 5 is a circuit diagram of a main part in a diaphragm control device for a solid-state imaging device showing a first embodiment of the present invention.

FIG. 6 is a circuit diagram of a main part in a diaphragm control device for a solid-state imaging device showing a second embodiment of the present invention.

FIG. 7 is an exploded perspective view of a galvanometer.

FIG. 8 is a schematic diagram for explaining the operation of the galvanometer.

FIG. 9 is a block configuration diagram of a conventional aperture control device.

FIG. 10 is a circuit diagram of a main part in FIG. 9 described above.

[Explanation of symbols]

 2 ... 1st diaphragm blade (diaphragm member) 3 ... 2nd diaphragm blade (diaphragm member) 5 ... torsion coil spring (biasing means) 5A ... tension coil spring (biasing means) 40 ... galvanometer (driving means)

Claims (2)

[Claims] 1. A diaphragm member, an urging means for urging the diaphragm member so that the diaphragm is in an open state, and a diaphragm member driven by electrical energy against the urging force of the urging means. A diaphragm control device for a solid-state imaging device, comprising: a driving unit. 2. A diaphragm control device for a solid-state image pickup device according to claim 1, further comprising control means for minimizing a current flowing through the driving means when the diaphragm is opened.