JPH0560962A - Focus adjustment device - Google Patents

Abstract

PURPOSE:To accomplish excellent zoom tracking with few errors by detecting a distance to an object at the time of starting zooming, selecting an optimum focus moving quantity, and correcting the focus moving at the time of zooming based on the selected result. CONSTITUTION:In the case of performing zooming to a telephoto side, a telephoto switch 602 is depressed, and an autofocusing(AF) control circuit 54 instructs an infrared range-finding circuit 14 to drive an LED so as to emit an infrared ray. The projected infrared ray is cast and reflected on an object, received by a semiconductor position detector(PSD), and outputted as a voltage signal corresponding to distance information. Furthermore, an arithmetic circuit calculates the distance l to the object based on the voltage signal and outputs it to a focus moving quantity selection circuit 151. Then, the circuit 151 selects the optimum spot of a tracking curve stored in a storage circuit 161 based on the obtained value l and outputs it to the AF control circuit 51 as the correction data of focus moving.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus adjusting device used in a camera-integrated VTR or the like.

[0002]

2. Description of the Related Art In recent years, an autofocus (hereinafter referred to as AF) system used in a camera-integrated VTR or the like is
By utilizing the fact that the amount of high-frequency components of the luminance signal in the video signal corresponds to the contrast of the captured image, the focus lens is drive-controlled so that this amount becomes maximum,
The so-called video AF method has become the mainstream. Video A
The F method has the advantage that it does not require a special distance measuring means and has a simple configuration, but in principle it is not possible to distinguish between the front pin and the rear pin, so it is always necessary to try to obtain the in-focus point. There is also a drawback that it requires an operation, it takes a long time to focus, and a subject with low contrast is poor.

On the other hand, in some cases, infrared rays are emitted to a subject to receive reflected light, the distance to the subject is obtained by triangulation, and the distance information is used to drive and control a focus lens. The method is also adopted. In this method, since the distance to the subject can be directly determined, the trial operation of the video AF method as described above is not necessary, and the presence or absence of the contrast of the subject is not affected. On the other hand, this method is not suitable for long-distance subjects or subjects with low infrared reflectance.

Therefore, recently, in order to obtain an AF system with a higher degree of perfection, an AF system using both of the above-mentioned methods has been considered. For example, according to Japanese Patent Application Laid-Open No. 2-2292, the distance information obtained by the infrared distance measuring method is used to determine the moving direction of the focus lens, the trial operation is eliminated, and the focusing response is improved. In addition, there is also a system in which any one of the methods is selected and used depending on photographing conditions such as a focal length and a subject distance.

However, what can be said in common with these prior systems is that these systems try to improve the so-called normal AF operation when the zoom is fixed. Regarding the operation during zooming, That is not mentioned.

By the way, in recent years, as the focus system of the zoom lens, an inner focus system in which an internal lens such as a compensator lens or a master lens is used as the focus lens is adopted instead of the conventional front lens focus system. Tend to This method is extremely advantageous in reducing the size and weight of the lens portion, has a small variation in the angle of view that adversely affects the AF operation, and allows continuous focus operation in the macro area.

However, in the zoom lens adopting the inner focus system, during the zoom operation,
There is a problem that the focus moves (out of focus) according to the change in the focal length. The amount of movement of this focal point also varies depending on the distance to the subject, and when trying to correct this amount of focal point movement, it is difficult to solve the problem, and there is currently no complete correction. Is.

In view of the current situation, the present invention describes one means for performing focus correction during zooming in an AF system that uses a video AF system and an infrared distance measuring system in combination with an inner focus system zoom lens.

FIG. 8 is a block circuit diagram showing the structure of a focus adjusting device using both the video AF method and the infrared distance measuring method in such an inner focus type zoom lens.
Reference numeral 01 is a fixed front lens for condensing, 102 is a variator for zooming, 103 is a compensator for correcting the image plane accompanying the movement of the variator 102, and 104 is a part of a relay lens used for focusing. With the master lens,
Although these lenses are composed of a plurality of lens groups, they are represented by one lens here.

Reference numeral 2 denotes a CCD, which converts the subject image formed by the zoom lens 1 into an electric signal. A camera signal processing circuit 3 includes a video signal V and a luminance signal Y (FIG. 9A).
Is output. 401 is a high-pass filter (hereinafter referred to as "HP
"F"), b (FIG. 9B) having a certain frequency or more of the luminance signal Y is passed. Reference numeral 402 is an amplifier, and 403 is a low-pass filter (hereinafter referred to as “LPF”), which outputs a signal C (FIG. 9C) in which unnecessary high frequency components of the output signal of the amplifier 402 are cut. 404 is a detector. , LP
A signal d having a gentle waveform by detecting the output signal of F403
(FIG. 9D) is output. An A / D comparator 405 converts the input signal d into a digital signal. An adder 406 digitally adds the data in the focus detection area set in the screen shown in FIG. This digital addition output y serves as a focus evaluation value (an index indicating a focused state). The HPF 401 to the adder 406 described above
The focus detection circuit 4 of FIG.

Reference numeral 54 is A to which the digital addition output y is input.
F control circuit, 6 is a zoom switch, wide-angle switch 60
1 and a telephoto switch 602, which notifies the AF control circuit 54 of the presence or absence of zoom change. Reference numeral 7 is a motor driver, which is based on a zoom command from the control circuit 54
The zoom motor 8 for moving is driven. A pulse motor driver 9 drives the pulse motor 10 that moves the master lens 104 for focusing based on a focus command from the AF control circuit 54. A potentiometer 11 detects the position of the variator 102, that is, the focal length, and outputs a potential signal corresponding to the lens position on a one-to-one basis. Reference numeral 12 denotes an end point detection switch for detecting an end point of the movable range of the master lens 104, which is turned on when the master lens 104 is focused on a subject at infinity, and represents the amount of movement of the master lens 104 with this position as a reference. ..

Reference numeral 14 is an infrared distance measuring circuit for detecting the distance to the subject, and its detailed structure is shown in FIG. In FIG. 11, 141 is a drive circuit that drives a light emitting body based on a command from the AF control circuit 54, 142 is an LED as a light emitting body that emits infrared rays for distance measurement to a subject, and 143 is infrared rays emitted from the LED 142. A light projecting lens that adjusts the luminous flux, 144 is a light receiving lens that receives reflected infrared light from a subject, 145 is a filter that equalizes the level difference depending on the distance of the received infrared light, and 146 is a PSD that is a sensor that detects the position of the light receiving spot. (Semiconductor position detector) 147 is a signal processing circuit that logarithmically compresses and amplifies the output signal of the PSD 146, and 148 is an arithmetic circuit that calculates the subject distance from the output of the signal processing circuit 147.

Next, the AF adjustment method by the video AF method and the object distance detection method by the infrared distance measuring circuit will be described in detail with reference to FIG. First, the video AF method A
The F adjustment will be described. The subject light incident through the zoom lens 1 is converted into an electric signal by the CCD 2 and becomes a video signal V through the camera signal processing circuit 3. The luminance signal component Y (FIG. 9A) of the video signal V is guided to the focus detection circuit 4, and the HPF 401 extracts the signal b (FIG. 9B) of the predetermined high frequency component. The signal b is amplified by the amplifier 402, then band-limited by the LPF 403 (FIG. 9C), and detected by the detector 404 (FIG. 9D). Further, it is converted into a digital value by the A / D converter 405, and the data in the focus detection area shown in FIG.
Is output as. That is, the focus evaluation value y is the integrated value of the high frequency component, and since this high frequency component corresponds to the contrast of the screen, the maximum contrast, that is, the maximum value when the master lens 104 is in focus,
The value becomes smaller as it deviates from the focal point. Therefore, the focus evaluation value y changes as the master lens 104 moves.
It has a mountain-shaped characteristic as shown in FIG. AF control circuit 5
Reference numeral 4 controls the pulse motor 10 so that the focus evaluation value y is always maximized, and drives the master lens 104 to the in-focus point.

Next, a method of detecting the object distance by the infrared distance measuring circuit will be described with reference to FIG. In the figure, 1 is the distance to the subject, a is the distance between the light projecting lens 143 and the light receiving lens 144, f is the focal length of the light receiving lens 144, and b is the distance to the light receiving spot position.
When a distance measurement command is issued from the AF control circuit 54, the drive circuit 141 drives the LED 142 to emit infrared rays. The infrared rays are adjusted into parallel rays by the light projecting lens 143 and projected onto the subject. The infrared light that hits the subject and is reflected is passed through the light receiving lens 144 and then filtered by the filter 14.
The level difference of the light quantity due to the distance is corrected by 5 to make it uniform, and the spot is connected on the PSD 146. PSD14
At 6, the current corresponding to the position of the light receiving spot is output, and the signal processing circuit 147 removes the influence of external light, amplifies it, and then performs logarithmic conversion for securing the dynamic range. Arithmetic circuit 1
At 48, the logarithmically converted voltage value is subtracted, sampled and held, and the voltage corresponding to the light receiving spot position is output to obtain the value of b. Here, since the values of f and a are known, the distance l to the subject is 1 = a /
It can be detected from b · f.

In the AF system combining the video AF method and the infrared distance measuring circuit as described above, for example, there is one that tries to eliminate the trial operation in the video AF. In other words, in the video AF method, it is not known whether the subject distance has changed or the subject itself has changed, even if the focus evaluation value y changes significantly. Therefore, the subject distance is determined by infrared distance measurement, and the operation of the master lens 104 is determined. Further, both types may be switched and used depending on the shooting conditions. In any case, these are for normal AF, that is, when the zoom is fixed, and nothing is said about the operation during zooming.

Next, FIG. 13 is a diagram for explaining a focus correction operation during zooming of a conventional focus adjusting apparatus in which an infrared distance measuring circuit is not used. Reference numeral 164 denotes a focus movement amount during zooming. A storage circuit 154 stores the movement amount of the lens 104, and a reference numeral 154 is a focus movement amount selection circuit for selecting the focus movement amount stored in the storage circuit 164 based on a command from the AF control circuit 55. The circuit 154 constitutes the focus correction circuit 134. Also,
Other parts are the same as those of the conventional example. When the zoom switch 6 is pressed and a zoom command is sent from the AF control circuit 54 to the motor driver 7 to drive the zoom motor 8, the variator 102 moves on the optical axis to perform zooming. At this time, the focus moves along with the movement of the variator 102, but the compensator 103 mechanically connected via a cam or the like simultaneously moves on the optical axis to correct the focus.

However, correction of only the compensator 103 cannot correct all focus movements, and as a result, FIG.
As shown in, the variator 10 is set for each distance to the subject.
Focusing cannot be achieved unless the master lens 104 is moved in accordance with the movement of 2. Therefore, in order to maintain the in-focus state even during zooming, it is necessary to move the master lens 104 along the curve shown in FIG. Hereinafter, this curve is referred to as a tracking curve.

That is, the tracking circuit of FIG. 14 is stored in advance as a storage circuit 164 as three parameters of the moving amount of the master lens 104, the focal length, and the distance to the object.
And the distance to the subject is assumed from the position information of the master lens 104 of the in-focus position obtained from the AF control circuit 54, and the tracking movement amount selection circuit 154 selects the tracking curve most suitable for correction. Memory circuit 16
Master lens 1
04 is to be moved. The above tracking curve is usually 20 to 3 considering the depth of focus at the telephoto end.
About 0 is stored.

The problem here is that, according to this method, if the focus is not surely set at the start of tracking, the correction will be out of focus until the end, and once zooming is started, it will occur during zooming. It is impossible to follow the movement of the subject, and further, when the zoom is performed from the wide angle side, the tracking curve is concentrated on the minimum movement amount of the master lens 104, so that the optimum curve cannot be selected. For these issues, see video A above.
Although it is possible to deal with this partly by performing the mountain climbing motion by F even during zooming, in that case also, since the focus evaluation value y changes greatly due to the change in the angle of view, there is a high possibility that the operation will be erroneous and sufficient tracking performance will be obtained. It wasn't.

[0020]

The conventional focus adjusting device is configured as described above, and the hill climbing method by the video AF or the method using the tracking curve is adopted for the operation at the time of zooming. However, these cannot follow the change of the focus evaluation value due to the change of the subject during the zoom operation or the change of the angle of view due to the zoom, and there is a high possibility that the correction will be erroneous, leaving a big problem in the zoom tracking operation.

The present invention has been made in order to solve the above-mentioned problems, and can be performed in any photographing condition,
An object of the present invention is to obtain a focus adjustment device that can perform good zoom tracking with extremely few errors, regardless of which zoom position the zoom operation is performed.

[0022]

SUMMARY OF THE INVENTION The present invention provides a focus adjusting device using a video AF system, a means for storing a focus movement amount used for focus movement during zooming, and a subject distance detection for detecting a distance to a subject. Means for selecting the focus movement amount corresponding to the distance information detected by the subject distance detection means from the storage means at the start of zooming.

Further, the video AF type focus adjusting device is provided with means for storing the amount of focus movement used for focus movement during zooming and subject detection means for detecting the distance to the subject. The focus movement amount corresponding to the detection distance information from the subject distance detection means is selected from the storage means, and the difference between the selected result and the focus movement amount at the time of focusing of the focus adjustment device is detected. At this time, the error is corrected with respect to the focus movement amount selected from the storage means.

Furthermore, in a video-type focus adjusting apparatus, a focus movement amount used for focus movement at the time of zooming, a storage means, a subject distance detection means for detecting a distance to a subject, and a change in focal length are detected. When the zoom is performed, the focal length change detecting means detects the distance to the subject by the subject distance detecting means each time the focal length change detecting means detects a predetermined amount of change in the focal length, and the focus movement corresponding to the detection result is detected. The quantity is successively selected from the storage means.

[0025]

According to the first aspect of the present invention, at the start of zooming, the optimum focus movement amount is selected by detecting the distance to the object by the object detection means, and the optimum focus movement amount is selected based on the selected result. The focal point movement is corrected.

In the second aspect of the present invention, at the start of zooming, from the focus movement amount based on the distance information to the subject detected by the subject detection means and the focus movement amount obtained from the focus position in the focus adjustment device, The optimum focus movement amount at the time of zooming is obtained and the focus movement is corrected.

According to the third aspect of the present invention, the distance to the successive subject is detected during zooming, and the optimum focus movement amount is obtained for each detection result, and the focus is determined based on the obtained result. The movement is corrected.

[0028]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a focus adjusting device of a camera-integrated VTR as an embodiment of the first invention of the present invention.
Reference numeral 151 denotes a storage circuit for storing a focus movement amount at the time of zooming, 151
Is a focus shift amount selection circuit that selects the focus shift amount stored in the storage circuit 161 from the distance information to the subject obtained from the infrared distance measuring circuit 14. The focus correction circuit 131 is used in the storage circuit 161 and the focus shift amount selection circuit 151. Make up. The other parts are the same as those in the conventional example. In the following description, the distance to the subject is 1, the focal length is f, and the movement amount of the master lens 104 is S.

Now, in the memory circuit 161, as shown in FIG. 2, the tracking curve for each distance to the subject is
The values of S of f = f _{0 to} f ₇ are stored respectively. In this figure, the case of a 1 m object is shown as an example. For example, a focus correction operation in the case of shooting a 1 m object at the wide-angle end as shown in FIG. 6 and zooming to the telephoto side will be described. As shown in FIG. 14, since the tracking curve is concentrated at the wide-angle end, the movement resolution of the master lens 104 is insufficient, so that the optimum tracking curve cannot be selected. In addition, there is a possibility that an incorrect selection may be made due to factors such as the influence of the depth of focus. Therefore, the telephoto switch 602 in the figure is pressed and the AF control circuit 5
1 issues an instruction to the infrared distance measuring circuit 14, and the LED 14 in FIG.
2 is driven to emit infrared rays. This projected infrared ray hits the subject, is reflected, is received by the PSD 146, and is output as a voltage signal corresponding to the distance information. The arithmetic circuit 148 calculates 1 from this voltage signal and outputs it to the focus movement amount selection circuit 151 of FIG. The focus movement amount selection circuit 151 selects the optimum one of the tracking curves stored in the storage circuit 161 from the value of l obtained by the above operation, and uses AF as correction data for the focus movement.
Output to the control circuit 51. That is, in FIG. 2, data of 1 = 1 m is selected, and since the wide-angle end, that is, f = f ₀ , the focus movement amount selection circuit 151 accesses the address “110000” of the storage circuit 161. Next, when f changes from f ₀ → f ₁ due to zooming, one address is updated (“110001”), and the obtained S data causes the AF control circuit 51 to move the master lens 104 up to S _1. To move. After that, the zoom continues and f changes from f _{1 to} f _2.
→ f ₃ … and S is updated to S ₁ → S ₂ → S ₃
The focus shift is corrected by moving the focus. By the way, in this method, depending on the number of tracking curves to be stored and the resolution of f and S, there is a portion where the deviation from the theoretical tracking curve becomes large. Therefore,
If the resolution is determined in consideration of this point, there will be no practical problem and accurate focus correction can be performed.

Example 2. An embodiment of the present invention will be described below. FIG. 3 is a block diagram showing a focus adjusting device of a camera-integrated VTR as an embodiment of the second invention of the present invention. In the figure, reference numeral 162 denotes a storage circuit that stores a focus movement amount at the time of zooming, and 152 denotes a focus movement amount selection that selects the focus movement amount stored in the storage circuit 162 from distance information to the subject obtained from the infrared distance measuring circuit 14. Circuit, 171
Is an offset detection circuit for detecting the difference between the position of the master lens 104 selected by the focus movement amount selection circuit 152 and the position of the in-focus master lens 104 obtained by the AF control circuit 54, and 181 is the focus movement amount selection circuit 152. Is a calculation circuit that adds the detection result of the offset detection circuit 171 to the selection result of the focus movement amount selection circuit 152 and the storage circuit 1.
The focus correction circuit 132 is composed of 62, the offset detection circuit 171, and the arithmetic circuit 181. The other parts have the same structure as the above-mentioned conventional embodiment.

In the following description, the distance to the subject is 1, the focal length is f, and the movement amount of the master lens 104 is S. Now, the storage circuit 162 stores a tracking curve described by predetermined l, f, and S as shown by the white circles in FIG. When the telephoto switch 602 is pressed and a zoom command is issued, the AF control circuit 52 causes the infrared distance measuring circuit 1 to operate.
4 is commanded to drive the LED 142 of FIG. 11 to emit infrared rays. This projected infrared ray hits the subject, is reflected, is received by the PSD 146, and is output as a voltage signal corresponding to l. The arithmetic circuit 148 calculates from the voltage signal that the current l is ln, and outputs it to the focus movement amount selection circuit 152 in FIG. Focus movement amount selection circuit 152
Then, the focus movement amount data corresponding to In is selected from the storage circuit 162 and output to the offset detection circuit 171 and the arithmetic circuit 181.

Next, the AF control circuit 54 informs the offset detection circuit 171 of the position of the in-focus master lens 104 at which the focus evaluation value y becomes maximum. For example, if the correction position of the selected tracking curve ln is point A and the position of the focal point is point B at the start of zooming, as shown in FIG. 4, the offset detection circuit 171 detects the points A and B. The difference (that is, two steps in the moving amount of the master lens 104) is detected as an offset. The arithmetic circuit 181 performs the following arithmetic operation to add the offset amount to the tracking curve ln selected from the memory circuit 162, outputs the arithmetic operation to the AF control circuit 52, and moves the master lens 104 according to the above arithmetic output to correct the focus. .. The locus of the correction is shown by the corrected tracking locus in FIG.

Example 3. An embodiment of the present invention will be described below. FIG. 5 is a configuration diagram showing a focus adjusting device of a camera-integrated VTR as an embodiment of the third invention of the present invention. In the figure, 191 is a focal length change detection circuit that detects a change in the focal length by a predetermined amount, 163 is a storage circuit that stores the amount of focus movement during zooming, and 153 is a storage circuit that uses the subject distance obtained from the infrared distance measurement circuit 14. The focus movement amount sequential selection circuit for sequentially selecting the focus movement amount stored in 163 constitutes the focus correction circuit 133 with the focal length change detection circuit 191, the focus movement amount sequential selection circuit 153, and the storage circuit 163. Other parts are the same as those of the conventional example.

In the following description, the distance to the subject is 1, the focal length is f, and the movement amount of the master lens 104 is S. Now, as shown in FIG. 2, the storage circuit 163 stores the values of S when f = f _{0 to} f ₇ for the tracking curves for each distance to the subject. In the figure, the case of a 1 m subject is shown as an example. For example, as shown in FIG. 6, a focus correction operation in the case of shooting a subject 1 of 1 m at the wide-angle end and zooming to the telephoto side will be described. As shown in FIG. 14, since the tracking curve is concentrated at the wide angle end, the master lens 104
The optimum tracking curve cannot be selected because the movement resolution of the is insufficient. In addition, there is a possibility that an erroneous selection may be made depending on factors that influence the depth of focus. Therefore, the telephoto switch 602 of FIG. 5 is pressed, and the AF control circuit 54 commands the infrared distance measuring circuit 14 to cause the LED 1 of FIG.
42 is driven to emit infrared rays. This projected infrared ray hits the subject, is reflected, is received by the PSD 146, and is output as a voltage signal corresponding to the distance information. The arithmetic circuit 148 calculates 1 from this voltage signal and outputs it to the focus movement amount successive selection circuit 153 of FIG. The focus movement amount successive selection circuit 153 selects the optimum tracking curve stored in the storage circuit 163 from the value of l obtained by the above operation, and uses it as the focus movement correction data for the AF control circuit. Output to 53. That is, in FIG. 2, the stored data of l = 1 m is selected, and the wide-angle end, that is, f = f
_Since it is ₀ , the focus movement amount successive selection unit 153 accesses the address “110000” of the storage circuit 163. Next, when f changes from f ₀ → f ₁ by zooming,
The address is updated by one (“110001”), and the AF control circuit 54 determines from the obtained S data that the master lens 10 has
4 is moved to S1. Hereinafter, f is f ₁ → f ₂ → f ₃
.. is updated, the focus movement is corrected by moving S as S ₁ → S ₂ → S ₃ .
In this method, the number of tracking curves to be stored, f,
Depending on the resolution of S, there is a portion where the amount of deviation from the theoretical tracking curve becomes large. Therefore, if the resolution is determined in consideration of this point, there is no problem, and accurate focus correction can be performed. When the zoom is continued and f is updated as f ₀ → f ₁ , this change is caused by the focal length change detection circuit 1
After being detected at 91, the AF control circuit 54 commands the infrared distance measuring circuit 14 again to project infrared rays, performs distance measurement, and confirms whether the distance to the subject has changed.

If the subject changes to the subject 2 having a distance of 3 m as shown in FIG. 6 when f ₃ → f ₄ , for example, the update of f detected by the focal length change detecting circuit 191 of FIG. 5 is performed. The change of the object distance can be quickly and surely determined by the infrared distance measurement executed in synchronization with. The focus shift amount sequential selection circuit 153 is 1 = 3 of the storage circuit 163.
The tracking curve of m is accessed to the data at the address position indicated by f ₅ in FIG. 7 to obtain the data of S = S _{5 ′} . Then, the AF control circuit 53 shown in FIG.
4 is moved and S ₄ → S _{5 'as} shown in FIG. 7, hereinafter l
If there is no change in the distance, the master lens 104 is further changed from S _{6 ′ to} S _{7 ′ as} the zoom becomes f ₆ → f _7, and the focus correction is continued.

Example 4. Although the pulse motor is used as the focus motor in the above embodiment, a motor having a function equivalent to this may be used instead of the pulse motor. Further, the number of tracking curves, the number of divisions of the focal length, and the number of steps of the pulse motor are not limited to those in the above embodiment. Further, the infrared distance measuring means as the subject distance detecting means may also use another distance measuring means as long as it has the same performance. In addition, as a method of storing the tracking curve, instead of directly storing the movement amount of the focus lens as in the present embodiment, the inclination of the tracking curve may be stored.

[0037]

As described above, according to the first aspect of the present invention, the storage means for storing the focus movement amount at the time of zooming is provided, and the distance to the object is detected by the object distance detecting means at the time of zooming. Since an appropriate focus movement amount is selected from the storage means based on the detection result and the focus is adjusted, good focus correction operation with few errors can be performed, and sufficient correction can be made especially when zooming from the wide-angle end. To enable.

As described above, according to the second aspect of the present invention, the storage means for storing the focus movement amount at the time of zooming is provided,
During zooming, the distance to the subject is detected by the subject distance detection means, an appropriate focus movement amount is selected from the storage means based on the detection result, and the difference between the detection result and the selected stored focus movement amount is used as an offset. Since it is held and the focus is adjusted, a good focus correction operation with few errors can be performed, and the capacity of the storage means can be small.

As described above, according to the third aspect of the present invention, the storage means for storing the focus movement amount at the time of zooming is provided,
At the time of zooming, the distance to the subject is detected by the subject distance detection means for each predetermined amount of change in the focal length, and an appropriate focus movement amount is sequentially selected from the storage means based on the detection result to adjust the focus. Therefore, a good focus correction operation with few errors can be performed, and a sufficient correction can be performed to promptly cope with a change in the subject distance during zooming.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a focus adjustment device according to an embodiment of the first invention.

FIG. 2 is a diagram illustrating stored data of a tracking curve.

FIG. 3 is a block diagram showing a configuration of a focus adjustment device according to an embodiment of the second invention.

FIG. 4 is a diagram illustrating an operation locus of the invention of FIG.

FIG. 5 is a block diagram showing the configuration of a focus adjustment device according to an embodiment of the third invention.

FIG. 6 is a diagram for supplementing infrared distance measurement.

FIG. 7 is a diagram illustrating an operation locus of the invention of FIG.

FIG. 8 is a configuration diagram for explaining an example of a conventional infrared distance measurement application.

FIG. 9 is a diagram showing operation waveforms of a focus detection circuit.

FIG. 10 is a diagram showing a focus zone.

FIG. 11 is a diagram showing a configuration of an infrared distance measuring circuit.

FIG. 12 is a diagram showing focus evaluation values.

FIG. 13 is a diagram showing a conventional example.

FIG. 14 is a diagram showing a tracking curve.

[Explanation of symbols]

 1 Inner focus type zoom lens 2 Focus detection circuit 8 Zoom motor 10 Pulse motor 14 Infrared distance measuring circuit 54 AF control circuit 131, 132, 133, 134 Focus correction circuit

[Procedure amendment]

[Submission date] March 26, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

The problem here is that, according to this method, if the focus is not surely set at the start of tracking, the correction will be out of focus until the end, and once zooming is started, it will occur during zooming. It is impossible to follow the movement of the subject, and further, when the zoom is performed from the wide angle side, the tracking curve is concentrated on the minimum movement amount of the master lens 104, so that the optimum curve cannot be selected. For these issues, see video A above.
While climbing behavior by F cope part in a way to run even during zooming, likely wrong operation so greatly changes the focus evaluation value y by the change in the angle of view that case, also <br/> add marrow In terms of sex, it was not enough either.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

Further, the video AF type focus adjusting device is provided with means for storing a focus movement amount used for focus movement at the time of zooming and subject distance detecting means for detecting a distance to a subject, and at the time of zoom start. , A focus movement amount corresponding to the detection distance information from the subject distance detection means is selected from the storage means, and an error between the selected result and the focus movement amount at the focus position of the focus adjustment device is detected. After that, the error is corrected with respect to the focus movement amount selected from the storage means during zooming.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction content]

Further, in the focus adjusting apparatus of the video AF system, means for storing the amount of focus movement used for focus movement during zooming, subject distance detection means for detecting the distance to the subject, and focal length change and a focal length change detection means for detecting, during zooming, each time the change in the focal length detection means for detecting a predetermined amount of the focal length change, and detects the distance to the by Rikomu Utsushitai the object distance detection means, the detection The focus movement amount corresponding to the result is successively selected from the storage means.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

[0025]

In the first aspect of the present invention, at the start of zooming, the object distance detecting means detects the distance to the object to select the optimum focus movement amount, and the zooming operation is performed based on the selected result. It is designed to correct the focus movement of the.

[Contents of correction]

[Procedure Amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

In the second aspect of the present invention, at the start of zooming, from the focus movement amount based on the distance information to the subject detected by the subject distance detection means and the focus movement amount obtained from the focus position in the focus adjusting device. , The optimum focus movement amount at the time of zooming is obtained and the focus movement is corrected.

Claims (3)

[Claims] 1. A focus adjustment apparatus comprising a focus adjustment means for adjusting focus using a high frequency component of a luminance signal and a subject distance detection means for detecting a distance to a subject. Based on the selection result of the focus movement amount selection means, the focus movement amount selection means for selecting from the storage means the focus movement amount corresponding to the detection distance result of the subject distance detection means, A focus adjusting device, comprising: a focus correcting unit that corrects a focus movement at the time. 2. A focus adjustment apparatus comprising focus adjustment means for adjusting focus using a high frequency component of a luminance signal, and subject distance detection means for detecting a distance to a subject. Storage means for storing the amount, focus movement amount selection means for selecting a focus movement amount corresponding to the detection result of the subject distance detection means from the storage means, selection result of the focus movement amount selection means, and focus adjustment means Error detection means for detecting an error from the focus movement amount of the adjustment result, selection result correction means for correcting the selection result of the focus movement amount selection means using the detection result of the error detection means, and the selection result correction A focus adjustment device comprising: a focus correction unit that corrects a focus movement during zooming based on a correction result of the unit. 3. A focus adjusting means for adjusting focus using a high frequency component of a luminance signal, a storage means for storing a focus movement amount at the time of zooming, and a focal length change detecting means for detecting a change in focal length. The object distance detecting means for detecting the object distance each time a change in the focal distance is detected by the focal distance change detecting means by a predetermined amount, and the focus movement amount corresponding to the detection result of the object distance detecting means. A focus adjustment apparatus comprising: a focus movement amount selection unit; and a focus correction unit that corrects a focus movement amount during zooming based on a selection result of the focus movement amount selection unit.