JPS6333720A - Focusing device - Google Patents

Abstract

PURPOSE:To fix the focusing speed by providing a control means which operates a driving force generating means which moves a focusing lens group at a speed corresponding to the detection output of a zoom lens by the extent of movement prescribed with a manual command signal. CONSTITUTION:A motor driving circuit 11 power-amplifies a motor driving signal to rotate and drive a stepping motor 8, and a focusing lens group 5 is moved in the direction of the optical axis. A control part 10 controls the moving speed of the focusing lens group 5 to a relatively high speed if the position of a variator lens group 3, namely, the zooming state identified by the detection output of a zoom lens 23 is set near the telephoto side, and the control part 10 controls said moving speed to a relatively low speed if said zooming state is set near the wide side. As a result, the time required for the change of the focus set distance in the full range between N and infinity is practically fixed whether the zooming state is set near the telephoto side or the wide side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a focusing adjustment device, for example, in a television camera or the like, which enables manual focusing by means of a driving force generating means that responds to the operation of a manual operating means.

[Prior art] Even during manual focusing, a driving force generating means such as a motor is operated in response to the operation of a manual operation element such as a distance ring or a switch, and the focusing lens is displaced by this driving force generating means to perform focusing. A focus adjustment device that performs focus adjustment has already been proposed. An example of this type of device is as follows. That is,
In a zoom lens, the position of the variator lens group,
The position of the convencator lens group necessary for focusing, which corresponds to the position of this variator lens group, is recorded in the storage means. The proposed device maintains the in-focus state by operating a driving force generating means such as a motor based on the output of the storage means and moving the compensator lens group to the in-focus position when the position of the lens is changed. (See Japanese Unexamined Patent Publication No. 143309/1983). This device can be used in autofocus mode for no-sum lenses (types in which the focus is adjusted by moving the convencator lens group, which is the rear element), in which the focus position changes when the variator lens group is moved to change the magnification. When the camera is in focus, adjustments are made constantly to maintain the focus state in order to eliminate the defocus state caused by zooming. However, during manual focusing, even if the focus state is once achieved, subsequent zooming Since a problem occurs in which the lens becomes defocused again, in order to solve this problem, as described above, the lens is moved by the driving force generating means even during manual focusing.

[Problems to be Solved by the Invention] Generally, when adjusting the focus of a zoom lens system as described above, a variator lens group is required depending on whether it is on the wide side or the telephoto side. The amount of displacement of the focusing lens group differs significantly. That is, on the wide-angle side, the displacement of the focusing lens group required for focus adjustment is extremely small compared to the telephoto side. Therefore, if the focusing lens group is adjusted on the wide side at the same speed as the moving speed of the focusing lens group on the tele side, the focusing lens group will almost instantaneously displace the entire range of movement from the close range corresponding position to the far distance corresponding position. It will end up being put away. Under such conditions where the focusing condition changes suddenly, it is extremely difficult to adjust the focus using manual focusing, which involves adjusting the focus without visually checking the image on the viewfinder or cathode ray tube image monitor. . Also, when the variator lens group is set to the telephoto side, focus adjustment is performed so that it comes into focus relatively slowly, but when it is set to the wide side, it comes into focus very suddenly. Because it changes, it gives an unnatural impression to the observer.

The present invention has been made in view of the above points, and by controlling the moving speed of the focusing lens group according to the zooming situation, the present invention can be used for all distances from close to long distances, regardless of the zooming setting. It is an object of the present invention to provide a focusing adjustment device in which the speed of focusing over an adjustment range does not substantially change.

[Means for Solving the Problems] The present invention provides a lens system including at least a variator lens group and a focusing lens group for adjusting focus;
A zoom sensor that detects the zooming state based on the position of the variator lens group, and a manual command that generates a manual command signal related to the moving direction and amount of the focusing lens group in manual focusing based on the operator's manual operation. a signal generating means, a driving force generating means for moving the focusing lens group, and a command signal in a direction specified by the manual command signal of the manual command signal generating means at a speed according to the detection output of the zoom sensor. control means for generating an output for operating the driving force generating means to move the focusing lens group by a movement amount defined by .

[Function] In the device of the present invention configured as described above, when the zoom sensor detects the position of the variator lens group and obtains a detection output representing the zoom setting state at a certain point in time, this output is controlled by the control described above. given to means. On the other hand, the operator operates the manual command signal generating means, which includes, for example, a manual switch, in order to perform manual focusing while monitoring the image on the finder or monitor screen. Manual Command A. The illusion generation means generates a manual command signal relating to the moving direction and amount of movement of the focusing lens group in accordance with this operation, and this signal is applied to the control stage.

The control means moves the focusing lens 11 by the amount of movement specified by the manual command signal of the manual command signal generation means in the direction specified by the manual command signal of the manual command signal generation means at a speed according to the detection output of the zoom sensor. emits the output of This output activates the driving force means, and the focusing lens J1 is displaced to perform manual focusing. Therefore, in the device of the present invention, the focusing speed in manual focusing is controlled depending on the zooming state at that time.

Embodiment FIG. 1 is a block diagram showing a focus adjustment device as an embodiment of the present invention. The apparatus shown in FIG. 1 is an application of the present invention to a video camera.

The imaging lens barrel 1 in the video camera includes a front lens group 2. Variator lens group 3. It has a built-in lens system including an aperture 4 and a focusing lens group 5 which is a so-called rear group lens. The variator lens group 3 and the focusing lens group 5 are each arranged to move +IJ in the optical axis direction. focusing lens l
Details of the mechanism for supporting i'#5 on the nJ automatic (1:) are shown in Figure 2.As shown in the figure, the focusing lens j! It is held by a lens holding frame 7 that is movable in the optical axis direction guided by a rod 6.The lens holding frame 7 has an engaging pin 7a or a protrusion in the radial direction of the lens. The engagement pin 7a is engaged with a feed screw 9 which is rotationally driven by a stepping motor 8 serving as a driving force generating means.Therefore, as the feed screw 9 rotates, the lens is rotated through the engagement pin 7a. The holding frame 7 is a focusing lens 7
! While holding T5, move along the optical axis direction in the direction of arrow A or arrow B. The stepping motor 8 is driven as a control means by a motor drive circuit 11 that supplies motor drive power based on the output of a control section 10. Further, as shown in FIG. 2, a zero point sensor 1 is provided on the lens holding frame 7 so as to protrude along the optical axis direction.
It is provided to correspond to 2. When zooming is set to the telephoto side and focusing is performed at infinity, the focusing lens 745
When the limit position in the direction B in the 71-node movement range is reached, the light shielding piece 7b of the lens holding frame 7 reaches the zero point sensor 12, and the zero point sensor 12 emits a detection output. In this apparatus, the position of the focusing lens group 5 at this time is its reference position (zero point). The output of the zero point sensor 2 is supplied to the control gas 10.

On the other hand, the variator lens group 3 described in FIG.
It is held in substantially the same manner as the focusing lens group 5, and can be moved along the optical axis direction by manual operation or by the motor 20.

The motor 20 is driven by a zoom motor drive circuit 22 that operates based on the operation of the zoom switch 21. The position of the variator lens group 3 moved along the optical axis direction is detected by a zoom sensor 23 including, for example, a position sensor in the form of a potentiometer or an encoder, and based on this, a detection signal representing the degree of zooming at that point is detected. is output from the zoom sensor 23 and supplied to the control s1o.

Further, the aperture value regarding the aperture 4 is detected by an aperture sensor 24, and the detection output of this aperture sensor 24 is provided to the control unit 10. An imaging probe 25 is arranged to receive the image obtained by the lens system into a captured image,
The photoelectric conversion output from the imaging probe 25 is sent to a video signal processing circuit 26, where it undergoes predetermined signal processing, and a video signal corresponding to the subject is obtained from the video signal processing circuit 26. The luminance signal of the video signal is also derived from the video signal processing circuit 26 and supplied to the high frequency component detection circuit 27 . The high frequency component detection circuit 27 extracts the high frequency component included in the luminance signal, and uses this as information regarding the degree of focus necessary for operation in the straight focus mode, which will be described later, to the control unit 27.
It is intended to supply In addition, the control section 1
0 is connected to an auto/manual changeover switch 28 and a manual switch 29 for performing focus adjustment operations in manual focusing mode. By changing the position of the auto/manual changeover switch 28, the control section 10 can select and switch between the autofocusing mode and the manual focusing mode. The focus setting distance corresponding to the operation of the manual switch 29 is displayed on a distance display device 30 such as a liquid crystal display device based on the output of the control unit 1O.

An outline of the operation of the apparatus of the present invention configured as described above will be explained below. By switching and selecting the position of the auto/manual changeover switch 28 to "manual", the operation mode of the control section 10 becomes the manual focusing mode. In this manual focusing mode, the operator adjusts the operation of the manual switch 29 and visually displays the image using a monitor or electronic viewfinder (none of which is shown) that displays the image using the video signal output from the video signal processing circuit 26. Check the focus status before adjusting the focus setting distance (focusing). Set the focus setting distance (focus) to the near side (
(hereinafter abbreviated as N side) or the far side (hereinafter abbreviated as N side).
Based on the operation of the manual switch 29 depending on whether the setting is to be set to the ω side (hereinafter referred to as ω side), the control unit 10 controls the zooming level corresponding to the degree of zooming identified by the signal given from the zoom sensor 23. A motor drive signal is output to the motor drive circuit 11 in order to move the focusing lens group 5 at a predetermined speed.

The motor drive circuit 11 amplifies the power of this motor drive signal and rotationally drives the stepping motor 8, thereby moving the focusing lens group 5 in the optical axis direction. In the control unit 10, when the position of the variator lens group 3 identified from the detection output of the zoom sensor 23, that is, the zooming state is set to a position close to the telephoto side, the moving speed of the focusing lens group 5 is compared. In order to increase the focusing speed, the moving speed of the focusing lens group 5 is controlled to be relatively slow when the focusing lens group 5 is set at a position close to the wide side. As a result, the focusing speed remains substantially constant whether the zooming state is set to the telephoto side or to the wide side. That is, the time required to change the focus setting distance over the full range between pJ and oo can be made substantially constant. Zooming adjustment can be made by operating the zoom switch 21 as described above, or by manually moving a zoom ring or the like (not shown).

Generally, in a lens system in which the rear lens group is a focusing lens group, as in this embodiment, even if the focusing lens group is once set to the in-focus position, it will become out of focus if the zooming state is changed. The control unit 10 stores data on the focusing lens position necessary to obtain focus according to both the zooming state and the set distance, and even if the zooming changes, the above data or calculations based on this data will be used. Proper position for constant focusing on focusing lens group: Beoto −
Perform racing-like control.

FIG. 3 shows a focusing lens group 5 for obtaining a focusing state that corresponds to both the zooming state and the focusing distance.
(ie, the amount of extension of the focusing lens I!15 from the reference position detected by the zero point sensor 12).

In Figure 3, the horizontal axis is focusing lens j; T5
The vertical axis shows the amount of feed from the above reference position, and the vertical axis is the tele (T).
), zooming status such as standard (S), wide (W), etc.
That is, the amount of movement of the variator lens group 3 is shown. Curve 9 indicated by a broken line is the focus setting distance, ! When it (focus) is "infinite (oo)", the curve j22 shown by the dashed dotted line is 1
When m, the focus of the curve g3 shown by the two-dot chain line is 0.
．． 5 shows the relationship between the amount of movement of the variator lens group 3 and the amount of extension of the focusing lens group 5 when the distance is 5 m. As can be easily understood from this diagram,
When the variator lens group 3 is at the position equivalent to tele (T), the amount of extension of the focusing lens group 5 to obtain focus for each focusing distance of ``infinity J, 1 m, and 0.5 m'' is , a2, a3. Also, when the variator lens 2!\3 is at the position equivalent to the standard (S), -1 - each of the focusing 1 nons JAY 5 to obtain focus for the focused setting distance The feeding amounts are bl, b2, and b3, respectively.Similarly, the variator lens group 3
The amount of extension of the focusing lens group 5 to obtain each of the above-mentioned focuses corresponding to the wide (W) equivalent position is cl, c2,
It is C3. As can be seen by comparing the shapes of the focusing curves Ω 9g and g3, the curvatures of the seven focusing curves with different focusing distances also differ. Therefore, it is extremely difficult to control the position of the focusing lens positioner using only mechanical means such as a cam in order to obtain a focused state for any zooming state and set focus distance. The device has a simple configuration in which the above-mentioned curve is traced using electronic storage and calculation means in the control section 10, so that a desired in-focus state can be obtained. Stores the focusing curve as data,
When determining the focusing lens position necessary for focusing by tonorsing this curve, in order to correspond to various focus setting positions, the focusing curve β and g described in 4.
It is necessary to set not only the curve f12 but also an extremely large number of curve groups, and to store all the data regarding these curves Jff in advance, but this requires a special storage means. It ends up. For this reason, in the apparatus of this embodiment, among the focusing curves 1-, the curve ρ1 corresponding to the set distance "infinite", the curve g3 corresponding to the set distance ro, and 5 mJ.
is stored as data in the storage means, and the focusing distance of the focusing lens B mechanism 5 corresponding to the set distance located in the middle of (-) is calculated by calculation. Divide the full range of the variable range of the set distance into 03, set the set distance as a value within this full range, and set the focusing curve N1 (setting path # Oo
) above, the amount of movement of the focusing 1 nonce group 5 is expressed as
, if the amount of extension of the focusing lens group 5 on the focusing curve 93 (set distance 0.5 m) is XN, then the amount of extension S of the focusing lens group 5 corresponding to the set distance can be determined as follows. can. Therefore, in the device of the present embodiment, the focusing curves g and l113 and {circle around (1)} are calculated based on the above equation (1) in accordance with the zooming information from the zoom sensor 23 and the focusing distance information from the manual switch 29. An appropriate focusing lens extension amount is calculated.

As shown in the figure, the horizontal distance between the focusing curve fI and 93 is wide when zooming is on the tele (T) side.
When it is on the wide (W) side, it is much narrower than on the T side. Therefore, from this figure 3, as mentioned above,
When zooming is set to the T side, the movement of the focusing single lens for focusing adjustment is relatively large, and when zooming is set to the W side, the movement of the focusing single lens for focusing adjustment is relatively large. It will be easily understood that the displacement of 7ff is extremely small. Therefore, in the device of the present invention, the focusing lens group is moved at a relatively high speed on the T side and at a relatively low speed on the W side, so that the rate of change in focus adjustment is substantially reduced regardless of zooming. I try to keep it constant.

On the other hand, by switching the auto/manual selector switch 28 to "auto" and selecting it, the controller
- The operation mode of the roll unit 10 becomes autofocusing mode. In this autofocusing mode, the control unit 10 receives information regarding the zooming state from the zoom sensor 23 and information regarding the aperture from the aperture sensor 24, and receives high-frequency components ( information), and calculate the appropriate position of the focusing lens group from each of these pieces of information (7. In order to position the focusing lens group at that position, a motor drive signal is output to the motor drive circuit 11. This♀ 111, even if the zooming or aperture conditions change, the focus lens group 5 is controlled to the appropriate position for focusing.

In the apparatus of the above embodiment, the control section 10 is configured with a microcomputer as its main part.

FIG. 4 is a block diagram showing the functions of the control section 10, and FIG. 5 is a flowchart showing details of the operation of the control section 10. Next, the functions and operations of the apparatus of this embodiment will be explained in further detail using FIGS. 4 and 5. In the embodiment shown in FIG. 4, an automatic return type seesaw type two-contact switch is used as the manual switch 29. When the auto/manual changeover switch 28 is set to the "manual" position, each functional section related to the manual focusing mode, which will be described below, becomes operational. Looking at the flowchart in Figure 5, this is the operation of the main routine that performs various calculation operations for autofocusing, monitoring of operation parts such as switches, and various known operations related to camera side control such as iris control. This is the part where the operation moves from to reading the state of the manual switch.

When the operator 29' of the manual switch 29 is rotated clockwise as shown in the figure, the contact 29a is closed and the set distance is changed to the near distance side (N side), and the operator is rotated counterclockwise. Then, the contact point 29b is closed and the set distance is changed to the infinity side (flash). Manual switch 29
Since one pole of each contact is grounded and the other pole is connected to a positive potential through a pull-up resistor, the other pole of the closed contact is connected to the ground potential during the opening time of the contact. It constitutes a manual command signal generation means that generates a manual command signal as follows. This manual command signal is read by the manual command signal identification section 110 of the control section 10.

When it is determined that any contact of the manual switch 29 is on, a discrimination operation for the next operation direction (determining which contact is on) is performed, and zooming is performed from the next zoom sensor 23. Move to the step of reading information about. When it is determined that any contact of the manual switch 29 is off, the process immediately moves to the step of reading information regarding zooming (
(See Figure 5). As shown in FIG. 4, the operating direction read by the manual command signal identification unit 110, that is, information on whether to further change the set distance to the (1) side or to the N side, is transmitted to the counting/frequency dividing unit 120. given to.

The counting/frequency dividing section 120 is always supplied with pulses output from the oscillating section 130 at a constant repetition frequency f, and these pulses are transmitted to the manual command signal identifying section 11.
It includes the function of a focus movement amount counter 121 for counting during the on-time of the manual switch 29 supplied from 0. The counted value in the focus movement amount counter 121 corresponds to the amount of change in the focus setting distance to be set by manual operation. A frequency division value corresponding to the zooming information read from the zoom sensor 23 is set in the frequency division value setting section 140, and this frequency division value information is supplied to the counting/frequency division section 120. The setting of the two-leg frequency division value is performed by searching the frequency division value data stored in advance in the memory in the frequency division value setting section in accordance with the output of the zoom sensor 23. When the frequency of the pulse signal output from the oscillation section 130 is set by the f1 frequency division value setting section 140 as m, the frequency of the pulse signal output after being divided by the counting/frequency division section 120 is f/m.

When the frequency division value setting unit 140 receives information from the zoom sensor 23 that the zooming is set closer to the telephoto side, the above-mentioned rn is set to a relatively small value, and on the contrary, it is set closer to the wide side. When this information is given, m is set to a relatively large value. A pulse signal with a frequency of f/m outputted from the counting/frequency dividing section 120 is given to the motor control section 200. The motor control unit 200 outputs a drive signal to the motor drive circuit 11 to drive the stepping motor 8 (see FIG. 1) at this f/m frequency. Therefore, when the zooming state is set to the telephoto side, the stepping motor 8
The rotational speed of the focusing lens group 5, that is, the moving speed of the focusing lens group 5, is relatively high;
15, and as described above, the rate of change in the sum j(- state becomes substantially constant regardless of the zooming setting.

Upper J! The operation after the step of reading the output of the zoom sensor 23 will be explained in detail based on the flowchart shown in FIG. 5 again. In the frequency division value setting section 140, the zooming information 'PtJ has changed compared to the data read last time (if it is determined that this has happened again), a new frequency division value m is reset, and the above f in the counting/frequency division section 120 /m is determined.On the other hand, even if the focusing distance is not changed, if the zooming state is changed, the position of the focusing lens I!Y5 is changed to 1 as explained in Fig. 3. If the distance is not adjusted, the in-focus state for the set distance cannot be maintained.Therefore, in this device, zooming information is given to the motor control section 200, and the in-focus state is adjusted according to changes in the zooming information. The motor controller 200 calculates the position of the focusing lens 7!Y5 to maintain the focusing lens 7! and a focusing curve storage unit 300, for example, a ROM or the like, in which data regarding g3 is set.
Based on the focus setting distance counter 201, which is an internal function, in order to recognize the data from
The position of the focusing lens 1 group 5 required for focusing is determined by equation (1) described in FIG. 3. A lens position recorder 210 is provided that stores the current value of the force single lens 115 while updating it each time it changes. It functions to send and receive information.

On the other hand, when the zooming information has not changed, whether or not the manual switch 29 is turned on is determined again by referring to the manual command signal identification section 11G, and when it is not turned on, the control section 10
The operation returns to the main routine again. When it is determined that the manual switch 29 is on, and when the motor control unit 200 calculates the amount of extension of the focusing lens group 5 following zooming as described above, the amount of movement of the focusing lens group 5 is stored in the lens position storage unit 210. According to the data,
Focusing lens? When the camera is at the focusing limit position in the IY5, inclination direction, or N direction (position on curve g or g3 in Figure 3), the direction of change of the focus setting distance that has already been determined exceeds the two-leg limit position. The motor control unit 200 checks whether the motor is in the wrong direction. As a result of this check, if it is determined that the setting is not in a direction exceeding the limit position, the value of the focus movement amount counter 21 of the counting/frequency dividing section 120 is read. This counter 1
The count value at 21 is when the manual switch 29 is turned on■! This is the number of manual pulses from the oscillation unit 130 counted during the period i, and as described above, this value corresponds to ±ΔD for changing the focus setting distance.

The value of the focus movement amount counter 21 is determined by the motor control unit 200.
is the current value of the focus setting distance. Addition/subtraction (Do±ΔD) to the value of the focus setting distance counter 201 representing
will be done. That is, the result of this addition/subtraction represents the new focus setting distance f4 D +. Motor control section 20
Substitute the value of 0 for D in equation (1) described in 1-U to create a new force single lens for maintaining focus. 1 position Sl is calculated. The value in the lens position storage section 210 is updated to the value of Sl determined in this way.

In the system of this embodiment, the position of the focusing lens group can be constantly recognized in the lens position storage unit 210 with relatively high resolution as a count value of relatively short-cycle pulses that are output from the oscillation unit 130. It has become. That is, the positions of the focusing lens group calculated by the motor control unit 200 according to the above equation (1) are all expressed with such precision. On the other hand, as explained in Figure 3, when zooming is set to the wide side, the focus is 1.
Since the amount of movement of the focusing lens group 5 for focusing is small, the number of rotational steps of the stepping motor 8 (see Figure 1) for focusing adjustment between ■ and N on the wide-angle side is smaller than that on the telephoto side. will also be extremely rare. Therefore, if the system were configured to recognize the position of the focusing lens group by the number of rotational steps of the stepping motor, one step between ■ and N on the wide side would correspond to several steps on the telephoto side. Therefore, the accuracy of the focusing lens group position on the wide-angle side is a fraction of that on the telephoto side. As a result,
After obtaining a certain focus state on the wide side, when moving the zoom state to the tele side, try to drive the focusing lens group along the focusing curve described in -1- to maintain focus. In this case, because the resolution of lens position expression on the wide side is coarse, it becomes impossible to specify the correct position for focusing on the telephoto side. In view of this point, in the system of the present embodiment, the lens position storage unit 210 always stores the above-mentioned information in the lens position storage unit 210, regardless of how many steps the focus setting distance between oo and 8 corresponds to, depending on the number of steps of the stepping motor. Since the focusing lens position is memorized with a constant i'::+ resolution as shown in FIG.

When the focusing lens 7ff position S is newly calculated as described above, this 81 and the current position S of the lens
. Then, it is calculated how many steps of the stepping motor 8 the 5l-8oO value obtained at this time corresponds to.

If 5l-So is less than one step, the process returns to the main routine. When the number of steps is calculated, the motor control section 200 issues a drive signal to the motor drive circuit 11 to drive the stepping motor 8 by the number of steps. When the stepping motor 8 has been driven the number of steps mentioned above, the motor drive circuit 11 is turned off and the process returns to the main routine.

The above is a description of the case in which the apparatus of this embodiment operates in manual focusing mode, and next, the case in which it operates in autofocusing mode will be described.

When the auto/manual changeover switch 28 is set to "auto", each functional section related to the autofocusing lens mode, which will be described below, is activated. Fourth
In the figure, an autofocus calculation control section 400 set in the control section 10 receives aperture information from the aperture sensor 24, zooming information from the zoom sensor 23, and an A/D conversion section from the above-mentioned high frequency component detection circuit 27. 50
Digitized focus information is provided via 0, respectively. Further, the autofocus calculation control section 400 is configured to exchange data with a storage section 410, and is also supplied with data from the above-mentioned focusing curve storage section 300. Autofocus control information output from the autofocus calculation control section 400 is given to the motor control section 200, and the motor control section 200
Based on this control information, the stepping motor 8 is rotated by the required number of steps through the motor drive circuit 11. The control method in the autofocusing mode of this embodiment device is basically the so-called mountain climbing servo method (NHK Technical Research Report Vol. 17 No. 1 (Continuous Volume 8
No. 6), page 21, ``Automatic focus adjustment of a television camera using the mountain-climbing servo system''). The principle of this method is as follows. The level of the high frequency component of the luminance signal becomes higher as the contrast of the image formed on the imaging surface of the imaging means becomes sharper. Therefore, the level of the high frequency component is focus level information indicating the degree of focus. This method first moves the lens, extracts the resulting change in focus level, and if the change is positive, the direction of the lens movement corresponds to the direction of focus. Move the lens in that direction, and if the change is negative, move the lens in the opposite direction to the movement direction, and repeat this movement to find the point where the focus level is maximum or the focus position It is something. In the apparatus shown in FIG. 4, the focusing lens group 5 is driven in minute steps, and each time a high frequency component detection circuit 27 detects an
/ The lens is sequentially driven in a direction in which the focus level becomes larger by comparing the focus level information 11) obtained via the D converter 500 with the immediately previous focus level stored in the 6 section 410. Focus, J,'
, performs section I operation.

The calculation related to this operation is performed by the autofocus calculation control section 40.
0 is performed.

On the other hand, the detected change in focus level varies depending on whether the contrast of the subject itself is low or not. As shown in Figure 6, for objects with high contrast, when the lens is at the in-focus position, there is a relatively large steep difference in level from when the lens is at the front focus and rear focus positions, as shown by the curve Ao. It is possible to obtain the focus level characteristics of a mountain shape where a peak is formed. However, for subjects with few contrasts and lasts, curve B
As shown in o, the focus level characteristic becomes a smooth curve. Therefore, with this method, focus detection can be performed accurately for subjects with a large amount of contrast.
Focus detection is relatively difficult due to contrast. For this reason, in the device of this embodiment, as shown in FIG.
A limit level L is set as a predetermined 1 novel corresponding to the level, and when the focus 1 novel is below the limit level L, the 1 horn power direction of the focusing 1 nons group 5 is set in the direction toward the normal focal position, and the focus level changes. Check it out, then gradually drive the lens and hit the pin! - It is designed to operate to search for the peak position of one novel. If the lens is already at the common focus position at the time of initial movement of the lens, the same operation is performed by moving it toward a short distance. The method of detecting the beak position described in 2 is as follows.

(1) Detect a point where the focus level is higher than the limit level and the focus level does not change even if the lenses are moved one by one. That is, near the top of the curve Ao shown in FIG. 6, the depth of focus actually occurs and the focus level does not change, so such a position is found.

(2) Curve B shown in Figure 6 as the focus 1 novel characteristic
If you can only obtain a gentle curve like o,
The initial movement direction of the lens is the direction toward the normal focal position, and the lens is scanned back and forth within the front and rear movement limit range,
During this scanning, the maximum value of the focus 1 novel is stored along with the number of driving steps of the stepping motor at each time point according to the gradual movement of the lens, and the final peak position of the focus level is found based on this storage.

Note that the operation (1) above takes priority over the operation (2) above, so that malfunctions in focus adjustment are minimized. Even if the operation starts with the first operation (2), if a clear peak value is found midway through, the operation 1) is performed. In addition, in the operation (2) described in -, if the focus level is below the limit indicated in -1- and bell L in the entire scanning range, set the lens to the normal focal position and energize the stepping motor. This increases the probability of focusing and saves power. In addition, the focus level when the lens is in focus or at the normal focus position is stored in the storage unit 410, and this stored 1
The current value of the focus level is constantly compared with the pin I level that is currently being scanned, and if the current value of the focus level is different from the memorized one novel value for a predetermined period of time, the stepping motor is Start (start the auto focusing operation +Jj.The reason for setting the above predetermined time is to prevent malfunctions due to noise, and when something temporarily crosses in front of the subject. This is to suppress hypersensitive reactions.

As mentioned in Fig. 3, in a device that drives the rear lens group to perform focusing, when the zooming state is set to the wide (W) side, this is necessary for focusing adjustment. The amount of movement of the lens is so small that fewer adjustments are needed, as is the case with fixed focus lenses. Furthermore, even when zooming is set to Shozo (S), if the aperture is stopped down considerably, the amount of lens displacement between oo m N will be substantially included within the depth of focus. become. Therefore, in the present embodiment, the focus calculation control section 400
, from the aperture sensor 24 and the zoom sensor 23,
Constantly reads aperture value and zooming information,
In a situation where the amount of adjustment displacement between -N is included within the depth of focus range, the focusing lens is set at a predetermined position within the depth of focus, and the autofocusing operation is automatically stopped. This is done to save power by cutting off the power to the stepping motor.

Furthermore, even in the normal autofocusing mode described above, the lens is not driven within the range that can be covered by the depth of focus, so the lens is
Compared to the case where the lens is moved over the entire interval, the actual range of lens movement is extremely limited, and a high-speed autofocusing operation is realized.

Generally, when focusing is performed by moving the rear lens group, it is possible to focus up to a close-up distance without so-called macro switching. However, if the lens is always moved for autofocusing over the entire range between close-up distance - (1), there is a risk that it will take time to obtain focus because the lens movement range is large. There is.

Therefore, in the device of this embodiment, the first distance range (1 m-
The range of Let's do it. This can be easily achieved by constantly counting and controlling the number of driving steps of the stepping motor. When performing autofocusing for a normal distance as described above, even if the subject is actually in the close-up position, if the contrast of the subject is sufficiently high or if the subject is close to 1 meter even in the close-up range, Since the focus level can be detected when the focusing lens reaches a position corresponding to a focusing distance of 1 m, the focusing lens group can be moved toward the position corresponding to close-up photography, and an appropriate focused state can be obtained. However, if the subject is within the close-up distance and the contrast is weak, it will be difficult to obtain an appropriate in-focus state as described above. In this example device, when the focus level is low, focus detection is performed while scanning the focusing lens group using method (2) described above for autofocusing operation, but this method is adjusted to correspond to the above-mentioned normal distance range. Scanning is performed first, and only when focus cannot be detected with this alone, scanning is performed in correspondence with the above-mentioned close-up distance range to detect focus. By doing this, so-called automatic focusing in a macro range is possible.

Note that if focus is not finally detected by scanning, the focusing lens group is forcibly set to the normal focal position. On the other hand, a subject at a close-up distance is
Since the photographer can clearly recognize this, the setting of the above-described autofocusing target L2 distance range can also be changed using a manual switch for macro switching (not shown).

Furthermore, a known distance sensor using infrared rays or ultrasonic waves may be provided to detect the distance range of the subject, and the configuration may be such that the autofocusing target range is switched between the two distance ranges described in 1- above. .

By doing so, high-speed and reliable autofocusing can be achieved.

On the other hand, the autofocusing calculation control section 400 is supplied with lens position data from the above-mentioned focusing curve storage section 300. In principle, the focusing curve Ω in Figure 3
It is impossible to obtain a focused state outside the range between 1 and g3, and the range in which the focusing lens can actually move is shown in Fig. 3 due to mechanical constraints on lens movement. limited to the indicated range Sv. For this reason, in the device of this embodiment, the above-mentioned range Sv is set in the focusing curve storage section 300, and control is performed so that the focusing adjustment does not deviate from this range under any circumstances. It is configured as follows.

FIG. 7 is a block diagram showing a modification of the system shown in FIG. 4 above. In FIG. 7, blocks corresponding to the blocks shown in FIG. 4 are designated by the same reference numerals, and detailed explanation thereof will be omitted. In the system shown in FIG. 7, a pushbutton type automatic return type single contact switch 290 is used in place of the seesaw type two contact manual switch 29 in the LIXA:S4 diagram.

While the contact 290a of the manual switch 290 is on, the focusing lens J: is moved by 5 yen. The control of the moving speed of the 1/ns at this time is performed in exactly the same manner as the system shown in FIG. 4 described above. Once the switch 290 is turned off and then turned on again, the direction of movement of the lens is reversed. That is, the on time of the manual switch 290 is recognized by the operation time setting section 111 in the control section 10A, and the counting/frequency dividing section is used as information regarding the on time of the manual switch 290, just as in the system shown in FIG. 120 is given. The operation time setting unit 111 also causes the off timer 112 to start measuring time from the time the manual switch 290 is turned off. If the time counting operation of the off timer 112 ends while the manual switch 290 remains in the off state, the movement direction setting section 113 is activated by the output of the off timer 112, and the direction of focus adjustment is forcibly directed toward the normal focus direction. Set it so that it can be dodged. The operation time setting section 111. A manual command signal identifying section 110A includes the off timer 12 and the moving direction setting section 113.

FIG. 8 shows a flowchart of the operation of the manual command signal identifying section 110A shown in FIG. 7 above.

Read the state of the manual switch 290 and close the contact 29
Determine whether 0a is on or off. When the contact 290a is on, the process moves to the next step of reading information from the zoom sensor 23. The subsequent operations are exactly the same as those described in Flowchart 1 of FIG. 5, and the explanation thereof will be omitted.

When the contact 290a is off, it is determined whether the off timer 112 has already finished its time counting operation. When it is determined that the off-timer 112 has completed the timing operation, the movement direction setting unit 113 forcibly sets movement direction information so that the focus adjustment direction is in the direction of the normal focal position. .

When it is determined that the timekeeping operation in the off-timer 112 has not ended, it is determined whether the timekeeping operation is a regular timekeeping operation that has been performed once initialized, and if it is a regular timekeeping operation. Return to the main routine.

When the time measurement operation is not normal, the off-timer 112 is initialized, the moving direction set by the moving direction setting section 113 is reversed, and the process returns to the main routine. This operation is
This corresponds to the state immediately after the manual switch 290 is turned off after being pressed.

In addition, in the devices of each of the above-described embodiments, switching between the manual focusing mode and the auto focusing mode is performed in one action by the auto/manual changeover switch 28, and when switching the operating mode, the operation mode is changed once in 11, I. The focus will not be disrupted. Therefore, there is no need to redo focus adjustment every time the operating mode is switched.

[Effects of the Invention] According to the present invention, since the moving speed of the focusing 1/lens group is controlled according to the zooming setting state, the moving speed of the focusing 1/lens group can be controlled from a close position to an infinite distance ( N -cy3'1 Focusing, 3.', In section 1, it is necessary to keep one sentence of focusing change constant, that is, to change the focus setting distance to the full range between N -. The time can be made substantially constant.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a focus and Ll'J node device showing an embodiment of the present invention. FIG. 2 shows details of a mechanism for supporting the focusing 1 nons group in FIG. Zuhan 1 Chengzu, 3rd
The figure shows the i! focus state depending on both the zooming state and the focus setting distance. ,; Figure 4 is a characteristic diagram of the focusing curve representing the position of the force single lens (T).
2 A block diagram showing the functions of the control section in the device shown in FIG. 1; FIG. 5 is a flowchart regarding the operation of the control section shown in FIG. 4; FIG. A characteristic diagram of the focus level obtained as the focus is adjusted, FIG. 7 is a book diagram showing a modification of the system shown in FIG. 4, and FIG. 8 is an operation of the system shown in -F2 FIG. 7. FIG. 3...Variator lens group 5...
...Focusing lens 1 (T8...
・・Stepping motor (drive generation means 10.1OA・
...Control unit (control means 11...
Motor drive circuit (driving force generation means) 23...Zoom sensor 29.290...Manual switch (manual command signal generator 110, ll0A...Manual command signal identification section (manual command signal generator

Claims (1)

[Claims] A lens system including at least a variator lens group and a focusing lens group movably provided for focus adjustment, and a zooming state detected based on the position of the variator lens group. a zoom sensor; a manual command signal generating means for generating a command signal related to the moving direction and amount of movement of the focusing lens group in manual focusing based on an operator's manual operation; and a driving force for moving the focusing lens group. generating means, and a speed corresponding to the detection output of the zoom sensor, for moving the focusing lens group in the direction specified by the manual command signal of the manual command signal generating means by the amount of movement specified by the command signal. A focusing adjustment device comprising: a control means that generates an output for operating the driving force generation means.