JPH08278440A - Image pickup device - Google Patents

Abstract

PURPOSE: To reduce power consumption without hindering automatic focusing operation in a compact video camera where a battery can be used. CONSTITUTION: The video camera is provided with a lens system having a variable power lens 102 and a focusing lens 105 correcting the change of an in-focus position associated with the variable power operation of the lens 102, a zoom motor 128 comprising a pulse motor driving the lenses 102 and 105 respectively, a focusing motor 126 and a zoom switch 131. When the lens 102 reaches a moving limit area in the midst of the variable power operation or when the variable power operation is stopped, a current to be supplied to each pulse motor is interrupted after stopping at a specified position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device such as a video camera or a still video camera.

[0002]

2. Description of the Related Art In the field of consumer-use image pickup devices such as video-integrated cameras, an inner focus type lens system is widely adopted because of its small size, light weight, and continuous shooting capability up to a short distance. There is.

On the other hand, functionally, an autofocus function (AF) has come to be provided as standard equipment, which reduces the burden on the operator and improves the operability.

Further, the automatic focusing function usually used in a video camera or the like extracts a high frequency component in a video signal and drives a focus lens (focus lens) so as to maximize the so-called mountain climbing. A system that performs control and is combined with the inner focus type lens system is becoming mainstream.

In such an inner focus type lens system, when the zoom lens is driven by driving the zoom lens, the focus position changes with the driving of the zoom lens. The compensator lens is driven according to the movement of the lens to correct the in-focus position that changes, so that the in-focus state can be maintained even during zoom operation, making electrical control easy. A pulse motor that can obtain high positional accuracy is used as a driving unit for each lens.

[0006]

However, in the above-mentioned conventional example, even when the pulse motor is stopped, current is supplied to maintain the rotational position (phase) of the pulse motor. However, this is a big problem especially for small video cameras that can be used in batteries.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide an image pickup apparatus with reduced current consumption.

[0008]

In order to achieve the above object, according to the invention described in claim 1 of the present application, a variable power lens (corresponding to the variable power lens 102 in the embodiment) and the variable power lens. A lens system (corresponding to the lens system 100 in the embodiment) having a focus lens (corresponding to the focus lens 105 in the embodiment) that corrects a change in the focus position due to the magnification changing operation of the magnification lens; A pulse motor (corresponding to the zoom motor 128 and the focus motor 126 in the embodiment) that drives each of the magnification lens and the focus lens, and an instruction unit that drives the pulse motor to instruct the zooming operation (in the embodiment, (Corresponding to the zoom switch 131), and when the zoom lens reaches the movement limit region while the zooming operation is instructed by the instructing means, Or, when the instruction means gives an instruction to stop the zooming operation, a control means (which corresponds to the lens control microcomputer 125 in the embodiment) for limiting the current supplied to the pulse motor after stopping at a predetermined position is provided. It has a different configuration.

According to the invention of claim 2 in the present application, in the configuration of claim 1, the control means is configured to cut off the energization to the pulse motor.

According to the invention of claim 3 in the present application, a variable power lens (corresponding to the variable power lens 102 in the embodiment) and a focus lens for performing focus adjustment (corresponding to the focus lens 105 in the embodiment). And a pulse motor (corresponding to the zoom motor 128 and the focus motor 126 in the embodiment) respectively driving the variable power lens and the focus lens. An imaging unit (corresponding to the image sensor 106 in the embodiment) that captures light that has passed through the lens system, and an extraction unit that extracts only a specific frequency component from the output of the imaging unit (the AF signal processing circuit 121 in the embodiment). (Corresponding to the above) and an instruction means (in the embodiment, the zoom When the zoom lens reaches the movement limit region while the zooming operation is instructed by the instructing means, or when the zooming operation is instructed by the instructing means, Based on the output of the extraction means, the focus lens is driven to the in-focus point, and the control means for limiting the current flowing to the pulse motor after a predetermined time after reaching the in-focus point (corresponding to the lens control microcomputer 125 in the embodiment). ) And are provided.

According to the invention of claim 4 in the present application, in the configuration of claim 3, the control means is configured to cut off the energization to the pulse motor.

According to the invention described in claim 5 of the present application, a variable power lens (corresponding to the variable power lens 102 in the embodiment) and a focus lens for performing focus adjustment (corresponding to the focus lens 105 in the embodiment). And a pulse motor (corresponding to the zoom motor 128 and the focus motor 126 in the embodiment) respectively driving the variable power lens and the focus lens. An imaging unit (corresponding to the image sensor 106 in the embodiment) that captures light that has passed through the lens system, and an extraction unit that extracts only a specific frequency component from the output of the imaging unit (the AF signal processing circuit 121 in the embodiment). (Corresponding to the above) and an instruction means (in the embodiment, the zoom (Corresponding to the switch 130), focus control means (corresponding to the AF switch 131 in the embodiment) for setting permission and prohibition of the automatic focus adjustment operation, and the automatic focus adjustment operation is permitted by the focus control means. In this state, when the zoom lens reaches the movement limit region while the zooming operation is instructed by the instructing means, or when the zooming operation is instructed by the instructing means, based on the output of the extracting means, In a state in which the focus lens is driven to the in-focus point and the current supplied to the pulse motor is limited after a predetermined time after reaching the in-focus point, and the automatic focus adjustment operation is prohibited by the focus control means. When the zooming lens reaches the movement limit region while the zooming operation is instructed by the instructing means, or when the zooming operation is instructed by the instructing means, (In the embodiment corresponds to the lens control microcomputer 125) control means for limiting the current supplied to the pulse motor and a structure in which a.

According to the invention of claim 6 in the present application, in the configuration of claim 5, the control means is configured to cut off the energization to the pulse motor.

[0014]

According to the first and second aspects of the present invention, when the variable power lens reaches the movement limit region during the variable power operation, or when the instruction means stops the variable power operation. The focus lens is stopped at a predetermined position, the current supplied to the pulse motor is limited, and power consumption is reduced.

According to the third and fourth aspects of the present invention, when the variable power lens reaches the movement limit region while the variable power operation is instructed, or when the variable power operation is stopped, extraction is performed. The focus lens is driven to the in-focus point based on the output of the means, and the current flowing to the pulse motor is limited after a lapse of a predetermined time after reaching the in-focus point, and the power consumption is reduced without impairing the performance of the automatic focusing operation. It

According to the fifth and sixth aspects of the present invention, when the zoom lens reaches the movement limit region during the AF operation and during the zoom operation, or when the stop of the zoom operation is instructed. In AF, the focus lens is driven to the in-focus point by the AF operation, and the current supplied to the pulse motor is limited after a lapse of a predetermined time after reaching the in-focus point. When the zoom lens reaches the movement limit area during zooming in the state where the AF operation is prohibited, or when the zooming operation is stopped, the current flowing to the pulse motor is limited and the automatic focus adjustment operation is performed. The power consumption can be reduced without impairing the performance of.

[0017]

Embodiments of the image pickup apparatus of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment in which the image pickup device of the present invention is applied to a video camera device, and an inner focus type lens system 100 is used.

In FIG. 1, the light from the subject is fixed to a first lens group 101, a second lens group (hereinafter referred to as a variable magnification lens) 102 for varying the magnification, a diaphragm 103, and a fixed lens. A third lens group 104, a fourth lens group (hereinafter referred to as a focus lens) 1 having both a focus adjustment function and a competition function for correcting the movement of the focal plane due to zooming.
After passing through 05, an image is formed on the image pickup device 106 such as CCD which constitutes the image pickup means of the present application.

The subject image formed on the image pickup surface of the image pickup device is photoelectrically converted by the image pickup device 106, sampled and held by a CDS (double correlation sampling circuit) 107,
The signal is amplified to the optimum level by the AGC 108, input to the A / D converter 109, and converted from an analog signal to a digital signal.

The video signal converted to a digital signal is input to the camera signal processing circuit in the subsequent stage and converted to a standard television signal, and at the same time, is input to the AF signal processing circuit 121. The AF signal processing circuit 121 constitutes an extracting means for detecting a focus by extracting a specific frequency component that changes according to the focus state from the video signal of the present invention.

In the AF signal processing circuit 121, the BPF 12
In step 2, only the high frequency component in the luminance signal is extracted, and the ABS (absolute value) circuit 123 converts it into an absolute value.
At 24, only the focus detection area in the screen is peak-held to generate an autofocus sharpness signal (AF evaluation value).

The lens control microcomputer 125 constituting the control means of the present invention reads the zoom switch 130 constituting the instruction means of the present invention for driving the variable magnification lens 102 to the tele side or the wide side, and the switch is turned on. When the zoom lens is pressed, a signal is sent to the zoom motor driver 129 to drive the zoom lens 128 via the zoom motor 128 so as to drive the zoom lens in the tele or wide direction.
Focus motor driver 127
To the focus lens 105 via the focus motor to correct the movement of the focal plane due to the zooming operation.

The AF switch 131 is a switch for turning on / off the autofocus operation. When the AF switch 131 is on, it is in the AF operation mode, and when it is off, it is in the manual focus adjustment mode. This AF switch corresponds to the focus control means of the present invention.

Further, the lens control microcomputer 125 is
When the F switch 131 is turned on and the zoom switch 130 is not pressed, a signal is sent to the focus motor driver 127 so that the sharpness signal for autofocus becomes maximum, and the focus motor 126 constituted by a pulse motor is used. By moving the focus lens 105, an automatic focus adjustment operation is performed.

Here, the algorithm of the autofocus operation will be described with reference to FIG. First, the AF switch 13
If 1 is ON (S201), AF operation is performed, so S2
If it is off (S201), the focus lens is stopped (S206).

The AF evaluation value from the AF signal processing circuit 121 is read (S202) and compared with the previously acquired AF evaluation value (S203). If it is larger than the previous time, the current drive direction of the focus motor 126 is maintained. As it is S205
If it is smaller, the focus motor 126 composed of a pulse motor is reversely rotated (S204) to S2.
In step 05, the focus motor 126 is controlled so that the AF evaluation value becomes maximum, and it is determined whether or not the focus is the AF evaluation value (maximum AF evaluation value) (S205). The focus motor 126 is stopped (S206), and the focus motor 126 is continuously driven unless the focus is adjusted (S206).
207).

Next, reference will be made to the relationship of the movements of the variable power lens 102 and the focus lens 105 when performing the variable power operation and the sharpness signal for autofocus during the variable power operation from the wide side to the tele side. Explain how.

In the inner focus lens system configured as shown in FIG. 1, since the focus lens 105 has both the competition function and the focus adjustment function as described above, even if the focal lengths are the same, the image pickup element 106 has The position of the focus lens 105 for focusing on the imaging surface varies depending on the subject distance.

When the position of the focus lens 105 for focusing on the image pickup surface is continuously plotted when the subject distance is changed at each focal length, a complicated locus is obtained as shown in FIG.

During zooming, if the locus shown in FIG. 3 is selected according to the subject distance and the focus lens 105 is moved so as to trace the locus, the in-focus state is always maintained. , Zoom operation without blur becomes possible.

On the other hand, in the front-lens focus type lens system in which the front lens is driven to adjust the focus, an independent compensator lens is provided for the variable-magnification lens, and the variable-magnification lens and the compensator lens are mechanical. Are connected by a conventional cam ring.

Therefore, for example, when a knob for manual zoom is provided on this cam ring and the focal length is manually changed, no matter how fast the knob is moved, the cam ring will follow this and rotate to change the magnification. Since the lens and the compensator lens move along the cam groove of the cam ring, if the focus lens is in focus, the above operation does not cause blurring.

However, in the control of the inner focus type lens system having the above-mentioned characteristics, when the zooming operation is performed while keeping the focus, the locus information of FIG. It is stored as a shape (a locus itself or a function with the lens position as a variable), locus information is read according to the position or moving speed of the variable magnification lens, and the focus lens is moved based on that information. There is a need.

FIG. 4 is a diagram for explaining an example of the trajectory following method proposed by the present applicant. In the figure, Z0, Z1, Z2, ... Z6 represent the zoom lens positions, and a0, a1, a2, ... A6 and b0, b.
1, b2, ... b6 are lens control microcomputers 1
25 is a representative locus stored in No. 25.

Further, p0, p1, p2, ...
It is a trajectory calculated based on one representative trajectory. The formula for calculating this locus is shown below.

P (n + 1) = | p (n) −a (n) | / | b (n) −a (n) | * | b (n + 1) −a (n + 1) | + a (n + 1) (1) According to the equation (1), for example, in FIG. 4, when the focus lens is at p0, the ratio by which p0 internally divides the line segment b0-a0 is obtained, and the line segment is calculated according to this ratio. The point internally dividing b1-a1 is p1. From the position difference of p1 -p0 and the time required for the variable power lens to move from Z0 to Z1,
You can see the moving speed of the focus lens to keep the focus.

Next, a case will be described in which the stop position of the variable power lens is not limited to only the boundary where the stored representative trajectory data is owned.

FIG. 5 is a diagram for explaining an interpolation method in the position of the variable power lens, in which a part of FIG. 4 is extracted and the variable power lens is arbitrary.

In FIG. 5, the vertical axis represents the focal lens position and the horizontal axis represents the variable lens position. The representative locus position (the focus lens position relative to the variable lens position) stored in the lens control microcomputer is changed. Double lens position Z0
, Z1, ... Zk-1, Zk ... Zn, the focus lens positions at that time are a0, a1, ... ak-1, ak ... an b0, b1 for each object distance. , ... bk-1, bk ... bn.

Now, if the zoom lens position is at Zx not on the zoom boundary and the focus lens position is Px,
When ax and bx are calculated, ax = ak- (Zk-Zx) * (ak-ak-1) / (Zk-Zk-1) ... (2) bx = bk- (Zk-Zx) * (bk-bk -1) / (Zk-Zk-1) ... (3)

That is, the current zoom lens position and two zoom boundary positions that sandwich the zoom lens position (for example, Zk and Zk-1 in FIG. 7).
In accordance with the internal division ratio obtained from, the four representative locus data stored (ak, ak-1, bk, bk-1 in FIG. 7) with the same subject distance are internally divided by the internal division ratio. By doing so, ax and bx can be obtained.

Then, according to the internal division ratio obtained from ax, Px, bx, the four representative data stored (in FIG. 5, ak, a
Of k-1, bk, bk-1), pk, pk-1 can be obtained by internally dividing those having the same focal length with the internal division ratio as shown in equation (1).

When zooming from the wide side to the tele side, the following focus position pk and the current focus position px
From the position difference between and, and the time required for the variable power lens to move from Zx to Zk, the moving speed of the focus lens for keeping the focus can be known.

When zooming from the tele side to the wide side, the following focus position pk-1 and the current focus position Px
From the positional difference between and, and the time required for the variable power lens to move from Zx to Zk-1, the moving speed of the focus lens for keeping the focus can be known.

The trajectory tracking method as described above has been proposed.

When the variable power lens moves in the wide direction from the telephoto side, as is apparent from FIG. 3, since the scattered loci converge, the focus can be maintained even by the above-mentioned locus tracking method.

However, in the wide-to-tele direction,
Since it is not known which trajectory the focus lens at the convergence point should follow, the similar trajectory following method cannot maintain the focus.

FIG. 6 is a diagram for explaining an example of a trajectory following method devised for the above problem. In both (a) and (b), the horizontal axis represents the position of the variable power lens, and the vertical axis (a) represents the level of the high frequency component (sharpness signal) of the video signal which is the AF evaluation signal.
(B) shows the position of the focus lens.

In FIG. 6, it is assumed that the focus cam locus for zooming a certain object is 604. Here, the focusing cam locus following speed on the wide side from the zoom position 606 (Z14) is positive (moved in the direction close to the focus lens), and the focusing cam locus following speed moving on the tele side from 606 to the infinite direction is negative. .

When the focus lens follows the cam locus 604 while maintaining the focus, the magnitude of the sharpness signal becomes 601.

Generally, in zooming while maintaining focus,
It is known that the sharpness signal level has a substantially constant value.

In FIG. 8B, the focus lens moving speed tracing the focusing cam locus 604 during zooming is Vf0. When the actual moving speed of the focus lens is Vf and zooming is performed with Vf0 tracing the cam locus 604 being increased or decreased, the locus is 60.
It becomes a zigzag locus like 5.

At this time, the sharpness signal level changes so as to produce peaks and valleys as indicated by 602. Here, locus 6
The size of 603 becomes maximum at the position where 04 and 605 intersect (the even point of Z0, Z1, ... Z16), and 603 at the odd point of Z0, Z1, ... Z16 where the moving direction vector of 605 switches. Will be at the minimum level.

602 is the minimum value of 603, but conversely 6
02 level TH1 is set, and the size of 603 is TH1.
When the moving direction vector of the locus 605 is switched every time when it becomes equal to, the moving direction of the focus lens after switching is
It can be set in a direction approaching the focus locus 604.

That is, the sharpness signal levels 601 and 602
Each time the image is blurred by the difference of (TH1), the moving direction and speed of the focus lens are controlled so as to reduce the blur, so that zooming with a suppressed blur amount can be performed.

By using the above-described method, in the wide-to-tele zooming in which the cam locus as shown in FIG. 3 diverges from the convergence, even if the focusing speed Vf0 is not known, the explanation is given with reference to FIG. With respect to the following speed (calculated using p (n + 1) obtained from the equation (1)), the switching operation is repeated as indicated by 605 while controlling the focus lens moving speed Vf (the sharpness signal level According to the change), it is possible to select a trajectory in which the sharpness signal level does not drop below 602 (TH1), that is, the blurring of a certain amount or more does not occur. Here, the moving speed Vf of the focus lens is determined by Vf = Vf0 + Vf + (4) Vf0 + Vf- (5), where Vf + is the correction speed in the positive direction and Vf- is the correction speed in the negative direction. At this time, the correction velocities Vf + and Vf- are set so that the inner angles of the two directional vectors of Vf obtained by the equations (4) and (5) are 2 according to the direction vector of Vf0
It is decided to be divided equally.

By changing the magnitude of the correction amount by the correction speed according to the subject, the focal length, and the depth of field, the increase / decrease cycle of the sharpness signal is changed to improve the selection accuracy of the tracking locus. Another method has been devised.

Next, referring to FIG. 8, the motor driver 127,
The operation of the motor 129 and the motors 128 and 126 will be described.

The pulse motors 128 and 126 are respectively composed of two coils CA811 and CB812 and a rotor 813 of a rotating portion, and are rotated by supplying sinusoidal currents having different phases of 90 degrees to the two coils.

The motor drivers 227 and 229 are each composed of two H bridge circuits and a control circuit 814.

801, 802, 803, and 804 are MOS
Each gate input A1, A2, A3, A4 of a transistor is connected to the control circuit 814.

The sources of the MOS transistors 801, 803 are connected to the power source, and the drains are connected to the coil CA811.

The drains of the MOS transistors 804 and 802 are connected to the ground via the resistor 809, and the sources are connected to the coil CA811. Similarly, 805, 80
6, 807 and 808 are also MOS transistors, and their gate inputs B1, B2, B3 and B4 are connected to the control circuit 814.

The sources of the MOS transistors 805 and 807 are connected to the power source, and the drains are connected to the coil CB812.

The drains of the MOS transistors 808 and 806 are connected to the ground via the resistor 810, and the sources are connected to the coil CB812.

FIG. 9 shows signals applied to the gates A1 to A3 and B1 to B3 of each MOS transistor when the control circuit 814 rotates in the direction instructed by the lens control microcomputer 125, and the waveform of the current flowing through the coils CA811 and CB812. Represent.

First, S0 to S4 will be described. A2
(902) is H, A3 (903) is L, A4 (904)
Is also L, and the A1 (901) gradually increases and decreases the ratio of the H period while repeating H / L, whereby the MOS transistor 802 is turned on, and 803 and 804.
Is off, 801 is repeatedly turned on / off according to the waveform of 901, and a positive sinusoidal current flows through the coil CA (9
09), the coil CA attracts the north pole of the rotor 813.

From S2 to S6, B2 (906) is H, B3 (907) is L, B4 (908) is L, and B1 is
(905) is a MOS by gradually increasing and decreasing the ratio of the H period while repeating H / L.
Transistor 806 is on, 807 and 808 are off, 8
05 repeats on / off, a positive sinusoidal current flows through the coil CB (910), and the coil CB is connected to the rotor 91.
Attract 3 south poles.

Next, S4 to S8 will be described. A4
(904) is H, A1 (901) is L, A2 (902)
Is also L, and the A3 (903) gradually increases / decreases the ratio of the H period while repeating H / L, whereby the MOS transistor 804 is turned on, and 801 and 802 are turned on.
Is off, 803 is on / off, a negative sinusoidal current flows through the coil CA (909), and the coil CA causes the rotor 8 to rotate.
Attract 13 south poles.

From S6 to S10, B4 (908) is H, B1 (905) is L, B2 (906) is L, and B3 is B3.
In (907), the MOS transistor 808 is turned on, 805 and 806 are turned off, and 80 is turned off by gradually increasing and decreasing the ratio of the H period while repeating H / L.
7 is turned on / off, a positive sinusoidal current flows through the coil CB (910), and the coil CB attracts the north pole of the rotor 813. After that, rotation is continued by repeating this.

When the motor stop command is received from the microcomputer 225, the coil CA and CB current values are also changed from S1 to S16 by moving to the respective positions of S1 to S16 and maintaining the same voltage or PWM duty. Stop while holding the current value at each position.

Next, the algorithm of the characteristic configuration and operation of the present invention will be described with reference to the flow chart of FIG. The processing shown in this flow chart is executed by the lens control microcomputer 125.

FIG. 16 is a diagram for explaining the algorithm of the embodiment. First, starting from S101, the AF switch 131 is checked in S102 to determine whether or not it is in the automatic focus adjustment mode.

If the result of determination in S102 is not the automatic focus adjustment mode, it is determined in S103 whether the tele-zoom key of the zoom switch 130 is pressed.

If the tele-zoom key is pressed here, it is determined in S104 whether the current variable-magnification lens position is a position where the variable-magnification lens cannot move, such as at the telephoto end.

If it is determined in step S103 that the tele-zoom key is not pressed, it is determined in step S105 whether the wide-zoom key is pressed, and then step S1 is performed.
At 06, it is determined whether or not the current variable lens position is a position where the variable lens cannot move, such as at the wide end.

If it is determined in S104 and S106 that the zoom lens can move, a zoom operation is performed in the direction in which the zoom key is pressed in S109. At this time, the focus lens is moved according to the locus for maintaining the focused state as shown in FIGS.

However, if it is determined in S104 and S106 that the zoom lens cannot move, S107
Stops the zoom motor and the focus motor at the stoptable position (stoppable phase), and immediately cuts off the coil currents of the zoom motor and the focus motor in step S108. Even when the wide zoom key is not pressed in S105, the process proceeds to S107 and each motor is stopped.

In the processing of S102, when the automatic focus adjustment mode is set, it is determined in S110 whether or not the zoom key on the tele side is pressed.

When it is determined in S110 that the tele-side zoom key is pressed, it is determined in S111 whether the current variable-magnification lens position is at a position where the variable-magnification lens cannot move, such as at the telephoto end.

If the tele-side zoom key is not pressed in S110, it is determined in S112 whether the wide-side zoom key is pressed, and then in S113, the current zoom lens position is changed to the wide end or the like. It is determined whether the double lens is in a position where it cannot move.

If it is determined in S111 and S113 that the zoom lens can move, the zoom operation is performed by referring to the AF evaluation value in the direction in which the zoom key is pressed in S114 (114).

However, if it is determined in S111 and S113 that the zoom lens cannot move, or if S105
If it is determined that the wide-side zoom key is not pressed in step S115, the AF evaluation value is checked in step S115 to determine whether the focus state is currently set.

If it is determined that the object is out of focus, S119 is set.
AF hill climbing operation is performed in the direction in which the AF evaluation value increases.
(119).

However, when it is determined in S115 that the focus is achieved, the zoom motor and the focus motor are stopped at the stoptable position while the motor coil is energized in S116. Then, after stopping, the elapse of a predetermined time is monitored in S117, and if the predetermined time has not elapsed, the operation from S102 is repeated, but when the predetermined time has elapsed, the current of the coil of each motor is cut off in S118. .

The motor stoppable position referred to here is shown in FIG.
The position of the motor such as S1, S2, S16, etc. is in a phase in which the motor can be stopped. Further, cutting off the current of the coil means setting all of A1 to A4 and B1 to B4 to the L level in FIG. 8 to put the coil in a high impedance state.

Accordingly, when the variable power lens reaches the movement limit region while the variable power operation is instructed, or when the instructing means instructs the stop of the variable power operation, the motor is moved to a predetermined stop position. After stopping, the current supplied to the pulse motor can be limited, and power consumption is reduced.

In the auto focus mode, when the variable power lens reaches the movement limit region while the variable power operation is instructed, or when the variable power operation is stopped, the output of the extraction means is output. Based on this, the focus lens is driven to the in-focus point, and the current flowing to the pulse motor is limited after a lapse of a predetermined time after reaching the in-focus point, and the power consumption is reduced without impairing the performance of the automatic focus adjustment operation.

In the above embodiment, the current of the motor coil is completely cut off, but the MOS transistors 804, 80
Of the 2,808 and 806 base inputs, H when stopped
The current flowing in the coil may be limited by lowering the level base input to the intermediate potential and increasing the resistance value of the MOS transistor.

[0091]

As described above, the claims 1 and 2 of the present application
According to the invention described in 2, when the variable power lens reaches the movement limit region during the variable power operation or when the stop of the variable power operation is instructed by the instructing means, the focus lens is stopped at a predetermined position. Since the current supplied to the pulse motor is immediately limited, the power consumption is reduced, which is particularly effective for devices using batteries.

According to the third and fourth aspects of the present invention, when the variable power lens reaches the movement limit region while the variable power operation is instructed, or when the variable power operation is stopped, The focus lens is driven to the in-focus point based on the output of the extraction means, and the current flowing to the pulse motor is limited a predetermined time after reaching the in-focus point. Since the motor can stand by in a state where it can immediately rotate until it is focused, it has an effect of reducing power consumption without impairing the performance of the automatic focus adjustment operation.

According to the fifth and sixth aspects of the present invention, when the zoom lens reaches the movement limit region during the AF operation and the zoom operation, or the suspension of the zoom operation is instructed. In this case, the focus lens is driven to the in-focus point by the AF operation, the current supplied to the pulse motor is limited after a lapse of a predetermined time after reaching the in-focus point, and the motor is controlled until the in-focus state is achieved during the automatic focusing. Since it can stand by in a state where it can be rotated immediately, there is an effect that power consumption can be reduced without impairing the performance of the automatic focusing operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an image pickup apparatus of the present invention.

FIG. 2 is a flow chart showing the operation of the embodiment of the present invention.

FIG. 3 is a diagram showing a characteristic curve obtained by plotting a change of a focal point position due to an operation of a variable power lens for each object distance.

FIG. 4 is a diagram for explaining a focus lens position control operation associated with the movement of a variable power lens.

FIG. 5 is a diagram for explaining a focus lens position control operation associated with movement of a variable power lens.

FIG. 6 is a diagram for explaining a control operation of the focus lens during the operation of the variable power lens in the auto focus mode.

FIG. 7 is a diagram for explaining an AF operation.

FIG. 8 is a diagram for explaining a pulse motor drive circuit.

FIG. 9 is a diagram for explaining the operation of the pulse motor drive circuit by the lens control microcomputer.

[Explanation of symbols]

 102 variable magnification lens 105 focus lens 106 image sensor 121 AF signal processing circuit 125 lens control microcomputer 126 focus motor 127 focus motor driver 128 zoom motor 129 zoom motor driver 130 zoom switch 131 AF switch

Claims (6)

[Claims] 1. A lens system having a variable power lens and a focus lens for correcting a change in a focus position due to a variable power operation of the variable power lens, and a pulse for driving the variable power lens and the focus lens, respectively. A motor, an instructing unit for driving the pulse motor to instruct a zooming operation, and when the zooming lens reaches a movement limit region while instructing a zooming operation by the instructing unit, or the instructing unit An image pickup apparatus, comprising: a control unit that limits a current supplied to the pulse motor after stopping at a predetermined position when an instruction to stop the scaling operation is given. 2. The image pickup device according to claim 1, wherein the control means is configured to cut off the power supply to the pulse motor. 3. A lens system having a variable power lens and a focus lens for adjusting the focus, a pulse motor for driving the variable power lens and the focus lens, and an image pickup means for picking up light passing through the lens system. An extracting unit that extracts only a specific frequency component from the output of the imaging unit; an instructing unit that drives the pulse motor to instruct a zooming operation; When the variable-magnification lens reaches the movement limit region, or when the instructing means instructs to stop the variable-magnification operation, the focus lens is driven to the in-focus point based on the output of the extracting means,
An image pickup apparatus, comprising: a control unit that limits a current supplied to the pulse motor after a predetermined time has elapsed after reaching the in-focus point. 4. The image pickup device according to claim 3, wherein the control unit is configured to cut off power supply to the pulse motor. 5. A lens system having a variable power lens and a focus lens for focus adjustment, a pulse motor for driving each of the variable power lens and the focus lens, and an imaging means for imaging light passing through the lens system. An extracting means for extracting only a specific frequency component from the output of the image pickup means; an instructing means for driving the pulse motor to instruct a zooming operation; and a focus control means for setting permission and prohibition of the automatic focus adjustment operation. In the state where the automatic focus adjustment operation is permitted by the focus control means, when the variable magnification lens reaches the movement limit region while instructing the variable magnification operation by the instruction means, or by the instruction means. When you instruct to stop the scaling operation,
The focus lens is driven to the in-focus point based on the output of the extraction means, the current supplied to the pulse motor is limited after a predetermined time after reaching the in-focus point, and the automatic focus adjustment operation is performed by the focus control means. In the prohibited state, when the zooming lens reaches the movement limit region while the zooming operation is instructed by the instructing means, or when the zooming operation is instructed by the instructing means, the pulse motor An image pickup device comprising: a control unit that limits a current flowing to the image pickup device. 6. The image pickup device according to claim 5, wherein the control means is configured to cut off the power supply to the pulse motor.