JPH05313055A - Lens drive controller - Google Patents

Abstract

(57) [Summary] [Purpose] To smoothly move the movable lens to the in-focus position. [Structure] Lens groups 1b and 1d movable in the optical axis direction
Position detecting means 7 and 8 for detecting the positions of the lens groups 1b and 1d in the light traveling direction, lens driving means for driving the lens groups 1b and 1d in the optical axis direction, and the lens group 1
and a lens control means 11 for controlling the thrust of the lens driving means by changing the value of the current flowing through the coils 4a and 4b of the lens driving means according to the moving directions of b and 1d.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens drive control device for driving a lens group such as a photographing lens in a camera / video camera or a projection lens in a video projector.

[0002]

2. Description of the Related Art Motors such as DC motors and stepping motors are often used as lens driving actuators in conventional lens driving control devices of this type.

FIG. 11 is a longitudinal sectional view showing a lens barrel of a conventional zoom lens for a video camera, and FIG. 12 is A- of FIG.
It is a longitudinal cross-sectional view taken along the line A. 11 and 12,
Reference numerals 101a to 101d are photographing lenses housed in a fixed barrel 102, 103, 104a, 104b are guide rods arranged in the fixed barrel 102 in parallel with the optical axis 105, and 106 is a direct current motor as a drive source, and an angle of view. A lens holding frame 111 that holds the taking lens 101b, which is a variator lens for making changes, is provided with an output shaft 106a and a gear train 1.
07, a screw rod 10 having a screw groove 108a
8. The guide rod 10 is inserted through the ball 110 that is pressed and engaged with the screw groove 108a by the pressing force of the pressing spring 109.
3 along the optical axis. Reference numeral 112 denotes a stepping motor as a driving source, which holds the photographing lens 101d for focusing and focus change due to a change in angle of view, and a lens holding in which the screw member 113 is integrally assembled to a sleeve portion 114a. The frame 114 is guided by the guide rod 104 via a screw member 113 that is screwed into the screw portion of the output shaft 112a.
It is moved in the optical axis direction along a and 104b. Reference numeral 118 is an IG meter that drives the shutter unit.

In recent years, cameras and video cameras have become smaller and smaller, and it is necessary to reduce the volume and weight while maintaining the same or higher level of functions than conventional ones. As one means for this, a magnet is arranged on the outer periphery of a lens holding frame for holding the lens, and a coil and a yoke are arranged on the outer periphery of the magnet to form a voice coil motor,
A system for driving the lens holding frame in the optical axis direction by this voice coil motor is described in, for example, Japanese Patent Application No. 2-20659. In the system described in this publication,
By making the optical axis of the voice coil substantially coincide with the optical axis,
We have realized a voice coil motor as a compact lens drive actuator.

FIG. 13 shows an application example of the voice coil motor, and FIG. 14 is a vertical section taken along the line BB of FIG. In FIGS. 13 and 14, the same parts as those in FIG. 12 are designated by the same reference numerals, and duplicate description will be omitted. Lens 101
The coil 117 wound around the yoke 117a and the bobbin 119 on the outer circumference of the lens holding frame 111 holding b1 to 101b3.
6 is disposed, the yoke 117b and the magnet 11 adhered to the yoke 117b are provided outside the coil 116 so as to face the yoke 117a.
5, the yokes 117a and 117b and the magnet 115 are attached to the fixed barrel 102. The lens holding frame 111 includes two guide bars 103 parallel to the optical axis 105.
It is held by a and 103b so as to be movable in the optical axis direction.

Since the magnet 115 is magnetized as shown, a magnetic field is formed between the yokes 117a and 117b in the radial direction. The coil 116 is the yoke 11
Since it exists between 7a and 117b and is wound in the circumferential direction, when a current is passed through this coil 116, a driving force is generated in the optical axis direction, and the bobbin 119 is integrated into a lens. Holding frame 111 and lens groups 101b1 to 101
b3 drives in the optical axis direction.

13 and 14 are of a type in which the magnet 115 is fixed and the coil 116 is moved, whereas FIG. 15 is of a type in which the coil is fixed and the magnet is moved. The magnet moving type in FIG. 15 is
The magnet 1 magnetized in the radial direction is provided on the outer peripheral portion of the lens holding frame 111 that holds the lenses 101b1 to 101b3.
15 is adhered to the inner circumference of the yokes 117a and 117b with a proper gap provided between the magnet 115 and the outer periphery of the magnet 115, and a coil 116 wound in the circumferential direction is provided. The lens holding frame 111 has two guide bars 1
03a and 103b hold the lens holding frame 1 so that it can move in the optical axis direction.
11 moves in the optical axis direction.

FIG. 16 shows an example in which a video lens system is formed by using the above-described voice coil motor. In this figure, the lens group 1 of the variable power variator lens is shown.
01b and the lens group 101d of the focus lens are driven by using a voice coil motor, and the magnet moves.

Since the video lens shown in FIG. 16 is a so-called rear focus lens in which focusing is performed by the lens group on the image plane side of the variator lens group,
The positional relationship that should be taken by the variator lens group and the focus lens group changes depending on the subject distance. This is shown in FIG.

In FIG. 17, the vertical axis is the focus lens position, the horizontal axis is the variator lens position, and the object distance is used as a parameter, and the cam locus to be followed by each lens group is shown. Therefore, it is necessary for each voice coil motor to maintain the in-focus state by deciding the speed / direction in which the lens group should move based on various information provided in the system. Below, these systems will be described in detail.

In FIG. 16, a variator lens group 1
01b and the focus lens group 101d, and encoders 121 and 122 for detecting the absolute position, respectively.
Is attached. This encoder 121,12
2 is a linear type volume or type that traces an electrode on which a gray code pattern is formed with a brush, or a type that performs position detection using a light emitting element such as iRED that moves together with the lens holding frame and a photoelectric conversion element such as PSD. Things etc. are considered.

The outputs from the encoders 121 and 122 are read by the reading circuits 123 and 124 and sent to the CPU 125. Also, the video signal from the CCD 126 is processed in the peak detection circuit 127,
The peak value of the luminance signal is extracted and sent to the CPU 125 as information regarding the current focus state.

FIG. 18A is a focus detection signal diagram in which the vertical axis represents the output value So of the peak detection circuit 127 and the horizontal axis represents the focus lens position. As shown in the figure, an approximate defocus amount is detected by the peak value So of the luminance signal. Based on this information and the information from the ROM 128 having the information about the cam locus shown in FIG. 17 as data, each voice coil motor (hereinafter, abbreviated as VCM) as a lens driving means in the CPU 125. The current value to be passed through the coils 129 and 130 or its waveform is determined, and the respective drivers 131 and 132 are
Then, a current flows through the coils 129 and 130. With the above system, the variator lens group 101b and the focus lens group 101d can maintain a positional relationship such that they are always in focus.

Next, a system from an unfocused state to a focused state, that is, an autofocus (AF) system, in which the variator lens group 101b is fixed will be described.

In FIG. 16, a drive signal of a constant cycle is sent from the oscillator 133 to the focus motor driver 132.
Is applied to the focus lens, the focus lens is driven so as to slightly vibrate in the optical axis direction. Then, the output from the peak detection circuit 127 also vibrates in synchronization with it. As shown in FIG. 18, if the focus lens is located closer to the in-focus position, the vibration of the lens and the phase of the video signal match, and if the focus lens is located farther, the phase shifts by 180 °. become.

Therefore, in FIG. 16, the output from the peak detection circuit 127 is input to the phase comparator 135 via the frequency detector 134 and compared with the phase of the oscillator 133 to determine the front pin / the rear pin. be able to. Further, the amplitudes of the outputs when the focus lens is located on the front focus side and the rear focus side are A _N and A _F , respectively, and are A _{M to} 0 during focusing.

When these signals are synchronously detected by using the output of the oscillator 133 as a reference timing, a signal S ₁ shown in FIG. 18B is obtained. That is, since the signal at the short distance has the same phase as the reference timing, the positive signal is output as the signal S _{1 for the} synchronous detection, and the signal at the long distance has the opposite phase to the reference timing. ₁ outputs a negative signal.

As described above, these amplitudes become 0 at the time of focusing, and the amplitudes increase as the defocus amount increases, so that the absolute value of the signal S ₁ also changes. Therefore, a current proportional to this signal S ₁ is applied to V. C. M
The lens can be brought into focus by flowing it to.

However, since the signal S ₁ becomes small when the blur becomes large, V. C. The current applied to M is also small.
Therefore, when the peak value So is smaller than the reference level V _{H, the} signal S ₁ is not used, but the signal S ₂ obtained by comparing the peak value So 1V before 1V and the current peak value So shown in FIG. Since this signal S ₂ is the output of the comparator, it is a signal having a constant value and only a code for driving the lens.
That is, when a large blurring V. This signal S ₂ C.
By supplying a current to M, the focus direction by driving the lens at a high speed, by performing the near Nuisance in focus, the operation of output S ₁ at the rate of signals S ₁ converges at a focal point to be zero , Automatic focus adjustment operation is performed. Also, this signal S
_{If the} motor speed based on ₁ is too high, the amount of overshooting of the in-focus position will increase, causing hunting, and if it is too low, there will be a problem that it will take time to reach the in-focus position. It is necessary to have a gain.

Further, as a basic method of controlling the motor, voltage (current) control for applying a voltage (current) proportional to the above-mentioned signals S ₁ and S ₂ to the motor and a relatively high motor armature circuit are used. On / off operation at a constant frequency and pulse amplitude control in which the amplitude is proportionally controlled by the above-mentioned signals S ₁ and S ₂ , the motor armature circuit is turned on at a relatively high constant frequency like this pulse amplitude control. There is a pulse width control in which the pulse width is proportionally controlled by the above-mentioned signal S ₁ and signal S ₂ after being turned off.

[0021]

However, in the above-mentioned conventional example, the V.V. C. Since the current flows through M, if the same thrust cannot be obtained even if the same current is applied depending on the moving direction of the lens due to, for example, a posture difference, the lens can be smoothly moved to the in-focus position. There is a problem that it is difficult to drive.

Further, the illustrated guide rod and lens holding frame 11
When there is friction on the sliding surface of No. 1 and the above-mentioned signal S ₁ is less than a certain magnitude, the motor-generated force is smaller than the above-mentioned friction (static friction force), and the movable part (lens holding frame)
Can not work. That is, there is a problem that it is impossible to position the lens holding frame 111 at a position having a higher focus level (peak value S ₀ ) while maintaining the stability of the motor in the vicinity of the focus.

An object of the present invention is to obtain a lens drive control device which solves the above problems.

[0024]

The present invention is a lens drive control device characterized by having the following configuration. (1) Lens group movable in the optical axis direction, lens position detecting means for detecting the position of the lens group in the optical axis direction, lens driving means for driving the lens group in the optical axis direction, and the lens group By providing the lens control means for controlling the thrust of the lens driving means by changing the value of the current flowing through the lens driving means according to the moving direction of the lens, it is possible to smoothly reach the focus position of the focus lens. Besides, it is possible to smoothly trace the cam locus during zooming. (2) A lens tilt angle detecting means for detecting a deviation angle between the optical axis of the lens group and a horizontal axis is provided, and a current supplied to the lens driving means is changed based on an output of the lens tilt angle detecting means. As a result, the lens can be stably moved to the target position even if a posture difference or the like occurs. (3) A boil coil is used as the lens driving means. (4) A first lens group that moves along the optical axis to perform a zooming action, and a second lens group that performs a correction and focusing action during zooming by the first lens group. Focus detection means for detecting the focus state, storage means for storing at least one threshold value for dividing the focus signal obtained by the focus detection means, focus signal obtained by the focus detection means, and By providing the lens control means for controlling the energization amount to the lens drive means for controlling the drive of each lens group in the optical axis direction based on the threshold value, the stability of the lens drive means in the vicinity of the focus is improved. It is possible to position the lens at a position with a higher focusing level while keeping it.

[0025]

【Example】

Embodiment 1 FIG. 1 is a drawing which best represents the features of the present invention.
C. It is a figure which shows the example which driven the lens group using M.
In FIG. 1, reference numerals 1a to 1d denote zoom lens groups,
Reference numeral b is a variator lens group for zooming, and 1d is a focus lens group. 2a and 2b are the zoom lens group 1b,
A lens holding frame for holding the focus lens group 1d, 3
a and 3b are magnets, and the lens holding frames 2a and 2b
A magnetized in the radial direction is bonded to the outer peripheral portion of the. Reference numerals 4a and 4b are coils wound in the circumferential direction, and are bonded to the lens barrel 5 with appropriate gaps provided on the outer circumferences of the magnets 3a and 3b.

The lens holding frames 2a and 2b are held so as to be movable in the optical axis direction by two guide rods 6a to 6d arranged parallel to the optical axis. Reference numerals 7 and 8 denote encoders that detect the absolute positions of the variator lens group 1b and the focus lens group 1d. The outputs from the encoders 7 and 8 are read by the respective reading circuits 9 and 10 and are sent to the CPU 11 as the lens control means. Sent. CC
The video signal from D12 is processed in the peak detection circuit 13, the peak value of the luminance signal is extracted, and sent to the CPU 11 as information regarding the current focus state.

Reference numerals 14 and 15 denote drivers, and the CPU 1
The applied voltage level or voltage waveform determined based on the focus state signal, the absolute position signal, etc. in 1 is applied, and a current is passed through the coils 4a and 4b. Also, in order to obtain a focus signal for the autofocus system, a frequency detector 16,
A phase comparator 17 and a reference frequency oscillator 18 are provided.

Reference numeral 19 denotes a lens inclination angle detecting device. As the inclination angle detecting device, for example, two liquids or gases (other water and air, water and oil) having different permittivities are provided between opposed electrodes. Enclosed and the same liquid (gas) depending on the tilt angle
Since the area of the electrodes facing each other through the body changes, the electric capacity changes due to this, and a detector or the like capable of detecting the attitude difference is conceivable. Reference numeral 20 denotes a ROM that has information about the cam locus as data.

Here, when a posture difference occurs, V. C. The relationship between the current applied to M and thrust is clarified as follows. That is, as shown in FIG. 2, when the optical axis is inclined by the angle θ with respect to the horizontal axis, V. C. The thrust force f when the current i is applied to M is given by f = Bil. Where B is the magnetic flux density across the coil and l is the effective length of the coil.

Now, assuming that the weight of the lens is M, at this time, the force f '= Mgsinθ due to gravity acts in the direction (-x direction) opposite to the direction in which the thrust acts, so the lens is driven in the x direction in the figure. The thrust F to be sought is F = Bil-Mg
sin θ (however, it is considered that the friction between the guide rod 6a and the magnet 3a that overlaps the sleeve portion is sufficiently small). From the above, the thrust loss (or increase) when the attitude difference θ occurs is given by Mgsin θ.

Therefore, based on the output of the tilt angle detecting device 19 described above, a voltage that causes a current to cancel thrust loss (or increase) in the CPU 11 is applied to the Mgsi.
By calculating from nθ and controlling the current flowing through each driver 14, 15, it is possible to make a system that stably controls the lens at the target position. Second Embodiment FIG. 3 is a diagram illustrating a second embodiment of the second embodiment when the lens tilt angle detection device 19 in the first embodiment is not used. C. It is a block diagram regarding a drive system of M. When the target value (sensor voltage value) at which the lens should be located is given, the sensor voltage value passes through the phase compensation filter 21 and the V.V. C. Converter 22 with resistance value (1 / R) determined by M coil
Is converted into a current i. With this current i, the calculation unit 23
The thrust force f for driving the lens is calculated by using the V.V. C. The lens is driven by M24, and the lens position is measured by the encoder (sensor) 25 and output as a voltage at every sampling period (Tsec). The subtractor 20 subtracts the voltage obtained by multiplying the voltage output by the loop gain K in the calculator 26 from the target value to bring the lens position closer to the target value.

In the system shown above, the present embodiment 2 is used.
Then, according to the flow shown below, the loop gain K in FIG.
To change.

First, V. C. The movement amount x _{R of} M24 per unit time and unit current is determined so as to be stable in the block diagram shown in FIG. Next, the moving amount x per unit time during driving, the moving amount x _R per unit current, and the previously determined moving amount x _R are calculated in the CPU 11 based on the outputs of the position detecting devices 7 and 8 in FIG. A new loop gain K'from x _R and x _R to K '= (x _R / x) K
Is calculated, and V. C. M.
By driving 24, it becomes possible to smoothly position the lens at the target position even if the thrust force varies depending on the moving direction due to a difference in posture or the like. Embodiment 3 FIG. 4 is a video camera lens system diagram showing Embodiment 3 using a boil coil motor as a lens group drive system, and the same parts as those of Embodiment 1 shown in FIG. Is omitted. In FIG. 4, reference numeral 27 is a ROM having data relating to the cam locus as data.

FIG. 5A is a focus detection signal diagram in which the vertical axis represents the output value S ₀ of the peak detection circuit 13 and the horizontal axis represents the focus lens position. A drive signal of a constant cycle is given to the driver 15 by the oscillator 18, and the focus lens group 1
When d slightly vibrates in the optical axis direction, the output value of the peak detection circuit 13 becomes A _N , A _F depending on the focus lens position (front pin, rear pin). In addition, when focusing A _M ~
It becomes 0.

A signal S ₁ shown in FIG. 5B is obtained by synchronously detecting these signals with the output of the oscillator 18 as a reference timing. Figure 5 also signal obtained by comparing the output value S ₀ and the current output value S ₀ of 1V previous peak detection circuit 13
It is the signal S ₂ shown in (c). FIG. C. The response characteristic of M is shown, in which the vertical axis represents the step amount of the movable portion (focus lens group 1d) when rectangular wave voltages having different pulse widths are input, and the horizontal axis represents the pulse width.
When the pulse width is a or less in the figure, the movable portion is the lens holding frame 2b.
The static frictional force on the sliding surface between the guide rods 6c and 6d cannot be exceeded, and it cannot move.

The drive control method for the focus lens group 1d is V. C. The M motor coil 4b is turned on and off at a proportionally high constant frequency, and the on-time is comparatively controlled in the CPU 11 based on the signals S ₁ and S ₂ .
± S _{1a in} FIG. 5 is the S ₁ value corresponding to the above-mentioned pulse width a when the drive pulse width is determined by the CPU 11 as described above, and is stored in the ROM 27 in advance.
Further, ± S _1b in FIG. 5 is stored in advance in the ROM 27 as one threshold value of the focused state. This ± S _1b indicates the signal S ₁ when the focus lens group 1d is driven and controlled. This is for selecting whether to determine the drive pulse width based on the above or the signal S ₂ .

Next, the drive control method of the focus lens group 1d during autofocus will be described with reference to the flowchart of FIG. First, the signals S ₁ and S ₂ obtained from the focusing signal are fetched into the CPU 11 (step ST1). Next, it is determined whether the signal S ₂ captured in step ST1 is positive or negative (step ST2). If the signal S ₂ is positive, the direction signal T _D = 1 is set (step ST3), and the direction pulse is output (step ST3). Step ST4). If the signal S ₂ is negative as a result of the determination in step ST2, the direction signal T _D = 0 is set (step ST5), and the process proceeds to step ST4 to output the direction pulse.

Next, the signal S ₁ acquired in step ST1
Is compared with the two thresholds S _1a and S _1b (step S
T6), if S _1a <S ₁ <S _1b , set the drive pulse width to T _P
= KS ₁ is determined (step ST7), and a drive pulse is output (step ST8). If S ₁ > S _1b , the drive pulse width is determined to be T _P = k ′S ₂ (step ST
9) Output drive pulse. If S ₁ <S _1a , the drive pulse width is set to T _P = a (step ST10), and the drive pulse is output.

According to the third embodiment described above, it is possible to position the focus lens more finely at the time of autofocus, and it is possible to position the focus lens group 1d at a position where the focus state is better. Embodiment 4 FIG. 8 is a video camera lens system showing Embodiment 4 using a voice coil motor as a lens group drive system, and the same parts as those in FIG. In FIG. 8, reference numeral 28 is a ROM which has information on the cam locus as data S _1a and S _{1b and} also has a change amount as data ΔS _1a .

FIG. 9 shows the output value S ₀ of the peak detection circuit 13 obtained in the same manner as in FIG. 5 and the signals S ₁ and S obtained by the modulation.
FIG. 6 is a focusing signal diagram showing ₂ .

± S _1a and ± S _1b in FIG. 9B are in-focus threshold values, and S _1a will be described later.
Similar to the third embodiment, ± S _1b is for selecting whether to determine the drive pulse width based on the signal S ₁ or the signal S ₂ when controlling the pulse width of the lens group. .. Further, in the fourth embodiment, the threshold value ±
S _1a is variable. This threshold value ± S _1a is changed by the driving direction signal based on the signal S ₂ , and the change amount is ± Δ.
S _1a Slice.

Next, the drive control method of the focus lens group during autofocus will be described with reference to the flowchart of FIG. First, the signals S ₁ and S obtained from the focusing signal
₂ is loaded into the CPU 11 (step ST21). Next, it is determined whether the signal S ₂ is positive or negative (step ST22), and if the signal S ₂ is positive, the direction signal T _D = 1 is set (step ST23), and the direction pulse is output (step ST2).
4).

If the result of determination in step ST22 is that the signal S ₂ is negative, the direction signal T _D = 0 (step S
T25), the process proceeds to step ST24 and the direction pulse is output.

Next, it is judged whether or not the direction signal T _{D of} this cycle is the same as the direction signal T _D 'of the immediately preceding cycle (step ST26), and if it is the same direction (T _D = T _D '),
It is determined whether the experience signal n is 0 or 1 (step ST2
7).

If the directions are different in step ST26, the signal S ₁ is compared with the threshold values S _1a and S _1b (step ST28). In step 27, if n = 0, a pulse width T _P = T _P + △ than the previous pulse width T _P as S _1a △ S _1a and only a large pulse width (step ST29), during the cycle Direction signal (T _D ′ = T _D )
Is suspended (step ST39), and a drive pulse is output (step ST30).

In step ST27, n = 1.
In the case of, it moves to step ST28. When the signal S ₁ is S _1a <S ₁ <S _1b in step ST 28, the pulse width is determined to be T _P = kS ₁ (step ST 31), and the experience signal n is set to 1 (step ST 32), and step ST 39 Move on to.

If S ₁ <S _1a in step 28,
It is determined whether the experience signal is n = 1 (step ST33), and n
Is 0, the pulse width is set to T _P = T _P −ΔS _1a (step ST34), the experience signal is set to 0 (step ST35), and the process proceeds to step ST39.

If n = 1 in step ST33,
The pulse width is set to T _P = a (step ST36), the experience signal n is set to 0 (step ST35), and step S
Move to T39. If S ₁ > S _1b in step ST 28, the pulse width is determined to be T _P = k ′S ₂ (step S
T37), and further, the experience signal n is set to 1 (step ST3
8) Then, move to step ST39.

In the fourth embodiment, even if there is a disturbance such as a posture difference during autofocusing, finer positioning of the focus lens position is possible, and the focus lens can be positioned at a position where a better focus is achieved. it can.

In the third and fourth embodiments, the basic lens drive control method is pulse width control, but voltage (current)
The same effect can be obtained by the control and the pulse amplitude control and the same means as described above. Although the voice coil motor is adopted as the focus motor, the same effect can be obtained by using the same means as described above even if a direct current motor such as a coreless motor is used.

[0051]

As described above, according to the first aspect of the present invention, the value of the electric current supplied to the voice coil motor of the third aspect as the lens driving means is changed according to the moving direction of the lens group, and the lens driving means is changed. Since the thrust force is controlled, the lens group can be smoothly moved to the in-focus position.

According to the second aspect of the present invention, the current supplied to the lens driving means is changed based on the output of the lens tilt angle detecting means. Therefore, the thrust force varies depending on the lens moving direction due to the attitude difference or the like. Even if the above occurs, it is possible to smoothly position the lens at the target position.

According to the fourth aspect of the invention, when the focus signal is larger than the threshold value, the pulse width proportional to the focus signal, and when the focus signal is smaller than the threshold value, the lens holding frame moves. Since a drive signal having a pulse width that enables the lens drive means is configured to be applied to the lens drive means, the stability of the lens drive means is maintained in the vicinity of the focus, and the lens group, that is, the lens The effect that the holding frame can be positioned is obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a lens drive control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a force relationship applied in the optical axis direction of a lens due to a posture difference.

FIG. 3 is a block diagram of a voice coil motor drive system according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram illustrating a lens drive control device according to a third embodiment of the present invention.

FIG. 5 is a focus detection signal diagram.

FIG. 6 is a response characteristic diagram of a voice coil motor.

FIG. 7 is a flowchart of focus lens drive control.

FIG. 8 is a configuration diagram showing a lens drive control device according to a fourth embodiment of the present invention.

FIG. 9 is a focus detection signal diagram.

FIG. 10 is a flowchart of focus lens drive control.

FIG. 11 is a vertical sectional view of a conventional zoom lens for a video camera.

12 is a vertical cross-sectional view taken along the line AA of FIG.

FIG. 13 is a transverse cross-sectional view of a lens barrel including a moving magnet type voice coil motor.

14 is a vertical cross-sectional view taken along the line BB of FIG.

FIG. 15 is an exploded perspective view showing a voice coil motor.

FIG. 16 is a configuration diagram of a conventional lens drive control device.

FIG. 17 is a cam locus diagram of rear focus zoom.

FIG. 18 is a focus detection signal diagram.

[Explanation of symbols]

 1a to 1d Lens group 7,8 Encoder (lens position detecting means) 3a, 3b Magnet (lens driving means) 4a, 4b Coil (lens driving means) 11 CPU (lens control means, focus detection means) 19 Lens tilt angle detection Means 27 ROM (storage means)

Claims (4)

[Claims] 1. A lens group movable in the optical axis direction, lens position detection means for detecting the position of the lens group in the optical axis direction, lens driving means for driving the lens group in the optical axis direction, A lens drive control device comprising: a lens control unit that controls a thrust of the lens drive unit by changing a current value flowing in the lens drive unit according to a moving direction of the lens group. 2. A lens tilt angle detecting means for detecting a deviation angle between an optical axis of the lens group and a horizontal axis is provided, and a current supplied to the lens driving means is changed based on an output of the lens tilt angle detecting means. The lens drive control device according to claim 1, wherein 3. The lens drive control device according to claim 1, wherein a voile coil is used as the lens drive means. 4. A first lens group that moves along an optical axis to perform a zooming action, and a second lens group that performs a correction and a focusing action during zooming by the first lens group. A focus detection means for detecting a focus state, a storage means for storing at least one threshold value for dividing a focus signal obtained by the focus detection means, and a focus obtained by the focus detection means. A lens drive control device comprising: a lens control means for controlling an energization amount to a lens drive means for driving and controlling each lens group in the optical axis direction based on a signal and the threshold value.