JPH07107362A - Video camera - Google Patents

Abstract

PURPOSE:To perform a smooth and high speed zoom operation all over the control areas by performing an image magnification/variable magnification operation by an optical zoom means and an electronic zoom means in the vicinity of the telescope end of the optical zoom means. CONSTITUTION:An optical zoom system performs a zoom operation by the same high zoom speed as that of the vicinity of a wide end by defining the zoom speed of an electronic zoom circuit as 0 (fixed to magnification ratio 1 as it is) in an area 1 from the wide end to the vicinity of the telescope end of the optical zoom system. In an area 2 from the vicinity of the telescope end to the telescope end, the overall zoom speed by the optical zoom system and the electronic zoom circuit is equalized to the high zoom speed in the area. In an area 3 on and after the telescope end, a zoom operation is performed by defining the zoom speed of the optical zoom system as 0 (fixed to maximum magnification) and equalizing the zoom speed to the high zoom speed in the vicinity of the wide end of the optical zoom system by the electronic zoom circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic zoom function for changing the image magnification of a subject by electronically processing a video signal picked up by an image pickup device, and at least a first lens group as a lens barrel. The present invention relates to a video camera that is fixed and has an optical zoom function that performs focus adjustment by moving a master lens and focus correction when varying the image magnification.

[0002]

2. Description of the Related Art Conventionally, as a lens system of a video camera used in a video recorder integrated with a camera, a so-called camcorder, it is generally possible to arbitrarily change the focal length within a predetermined range to change the image magnification of a subject. A zoom lens system is used. As a zoom lens system, in recent years, in particular, in order to miniaturize a video camera, in recent years, the first lens group on the subject side is fixed and the rear master lens is moved and controlled to perform focus adjustment and focus correction during zooming. A so-called rear focus zoom type lens system for performing the above is often used.

FIG. 3 is a schematic configuration diagram of a rear focus zoom type lens system. This rear focus zoom type lens system (hereinafter referred to as an optical zoom system) 1 faces from the subject side on the left side to the right side in the figure. The first fixed lens 2 sequentially arranged along the optical axis,
A zoom lens 3, a diaphragm 4, and a second fixed lens 5 that move in parallel with the optical axis to perform zooming (magnification change), and move in parallel with the optical axis to perform focus adjustment and focus correction during zooming. It has a master lens 6.

The zoom lens 3 is moved by a zoom motor 7, and its position is detected by a zoom encoder 9. The master lens 6 is moved by the focus motor 8, and its position is detected by the focus encoder 10. In FIG. 3, 11 is a zoom switch, 1
Reference numeral 2 is a lens control microcomputer that controls the zoom motor 7 and the focus motor 8, and 13 is an image sensor that converts an optical subject image projected by the optical zoom system 1 into an electric signal.

In the optical zoom system 1 having such a configuration, when the subject distance changes, the master lens 6 is moved so that the subject image is correctly formed on the image pickup device 13 to perform focus adjustment. Further, when the zoom lens 3 is moved to change the image magnification, the subject image is not correctly formed on the image pickup device 13 as it is, so the master lens 6 is moved to perform focus correction.

For such focus adjustment and focus correction, based on the positions of the zoom lens 3 and the master lens 6 detected by the zoom encoder 9 and the focus encoder 10, the lens control microcomputer 12 controls the zoom motor 7 and the focus motor 8. Drive control.

As described above, in the optical zoom system 1,
Focus correction during zooming is performed by moving the master lens 6 using the lens control microcomputer 12, but if the focal length is changed while keeping the zoom amount per unit time, so-called zoom speed, constant, On the long focal length side of the lens system 1, that is, near the so-called telephoto end, the focus correction amount due to the movement of the master lens 6 becomes too large and exceeds the calculation speed of the lens control microcomputer 12, resulting in a blurred subject image near the telephoto end. I will end up.

FIG. 4 shows the optical zoom system 1.
FIG. 6 is a diagram showing a zoom speed controlled according to a focal length, and the zoom speed is reduced near the telephoto end in order to prevent the subject image from being blurred as described above.

By the way, in recent years, due to advances in digital signal processing, image signals read from an image sensor are thinned out.
Alternatively, an electronic zoom circuit that electronically enlarges the image magnification of a subject by intermittently reading a video signal from the image sensor, generating an interpolation signal from the video signal, and inserting the interpolation signal into the video signal Is proposed.

FIG. 5 is a block diagram showing the simplest example of the electronic zoom circuit.
Scan timing pulse generation means 21, image sensor 13, correlated double sampling (CDS) circuit 22, AGC circuit 2
3, AD converter 24, signal processing circuit 25, memory circuit 2
6 and a DA converter 27.

FIG. 6 is a time chart showing the scanning timing of the image sensor 13, showing a vertical transfer pulse (A), a horizontal transfer pulse (B), a horizontal scanning pulse (C), and a scanning timing pulse (D). ing. The vertical transfer pulse (A) and the horizontal transfer pulse (B) are generated by the scanning timing pulse generating means 21.

FIG. 7 is a conceptual diagram showing an image when the image magnification is enlarged, and shows the light receiving surface 31 of the image pickup device 13 and the monitor screen 32. The image sensor 13 of FIG.
In the light receiving surface 31 of No. 3, the area to be enlarged is surrounded by a frame, and the other unnecessary areas are shown by hatching.

If the enlargement ratio of the electronic zoom circuit 50 is doubled, only the area to be enlarged on the light receiving surface 31 of the image pickup device 13 shown in FIG. The vertical transfer pulse (A) for driving the vertical CCD (not shown) is driven at high speed to sweep out unnecessary charges in the shaded area in the vertical direction of the light-receiving surface 31 of the image sensor 13, and in the enlargement target area, two horizontal scans are performed. One vertical transfer pulse (A) is generated for each pulse (C) to read the image sensor output signal (D). At this time, the enlargement ratio (2
In response to a control signal from the scanning timing pulse generating means 21, one signal is output from the image sensor 13 to two scanning lines in order to intermittently read out a signal in the horizontal scanning direction in the vertical direction in accordance with
The image sensor output signals (D) are thinned out and read at the rate of books.

The image sensor output signal (D) read in this way is correlated double sampling (CDS) circuit 22.
The bass noise component is removed by the AGC circuit 23, the amplitude is controlled by the AGC circuit 23, and the signal is converted into a digital signal by the AD converter 24. Then, the image sensor output signal (D) converted into a digital signal is subjected to gamma processing by the signal processing circuit 25,
Predetermined processing such as color signal processing is performed and sent to the memory circuit 26.

The memory circuit 26 calculates the average value of two adjacent scanning lines and interpolates the average value between the two scanning lines to perform vertical interpolation.
Further, by prohibiting the reading or writing of the digital data of the video signal corresponding to the unnecessary area in the left-right direction of the light-receiving surface 31 of the image sensor 13, the memory circuit 2
Horizontal interpolation is performed by interpolating the average value of these two digital data between the digital data of the video signals which are discarded in 6 and correspond to the enlargement target area.

The digital signal, which has been subjected to the vertical and horizontal interpolations, is converted back into an analog video signal by the DA converter 27, and an image of the image on the monitor screen 32 is obtained. Even if the enlargement ratio is other than double, it is possible to continuously obtain an arbitrary enlargement ratio by appropriately selecting the ratio of the image pickup element and the interpolation signal in the video signal.

Further, by using the optical zoom system 1 and the electronic zoom circuit 50 in combination as described above, a compact and lightweight zoom lens system having a large zoom magnification can be realized.

In the zoom lens system according to such a combination, the change of the image magnification in the electronic zoom circuit 50 is
Since processing such as thinning and interpolation is performed on the original video signal, the image quality deteriorates to some extent. Therefore, when performing so-called zoom-up for changing from a small image magnification to a large image magnification, first, the enlargement ratio in the electronic zoom circuit 50 is set to 1, that is, without performing the enlargement in the electronic zoom circuit 50, The image magnification is changed only by the optical zoom system 1, and after the optical zoom system 1 reaches the telephoto end, the electronic zoom circuit 50 is used to change the image magnification.

When a so-called zoom-down is performed in which the image magnification is changed from a large image magnification to a small image magnification, the image magnification is changed only by the electronic zoom circuit 50 at first, and the enlargement ratio in the electronic zoom circuit 50 is increased to 1. After reaching, the optical zoom system 1 is used to change the image magnification.

FIG. 8 is a diagram showing the control state of the zoom speed corresponding to the change of the focal length in the above case,
(A) is the zoom speed of the optical zoom system 1,
(B) is the zoom speed of the electronic zoom circuit 50, (C)
Shows the zoom speed when the optical zoom system 1 and the electronic zoom circuit 50 are used together.

[0021]

However, when the optical zoom system 1 and the electronic zoom circuit 50 are used together, the zoom is performed in order to eliminate the problem that the subject image is blurred near the tele end of the optical zoom system 1. Since the speed is slowed down, as shown in FIG. 8, if the electronic zoom operation after the tele end is performed with the zoom speed near the tele end being maintained, the zoom speed becomes slow in the control area of the electronic zoom circuit 50. There was the first problem.

In order to solve the first problem, for example, when switching from zooming by the optical zoom system 1 to zooming by the electronic zoom circuit 50, it is temporarily delayed near the tele end of the optical zoom system 1 as described above. If the zoom speed is suddenly increased, the zoom speed suddenly changes, which may cause a second problem of an unnatural image. It is expected that the same problem will occur when the zooming by the electronic zoom circuit 50 is switched to the zooming by the optical zoom system 1.

The present invention has been made under such circumstances, and a first object thereof is to realize a smooth and high-speed zoom operation over all control regions of optical zoom control and electronic zoom control. It is to be able to do it.

A second object of the present invention is that when the optical zoom control and the electronic zoom control are switched, an unnatural image does not occur, and blurring does not occur near the tele end of the optical zoom means. The objective is to realize a zoom operation that does not reduce the zoom speed even in the electronic zoom control area.

[0025]

In order to achieve the first object, the video camera according to the first invention electronically processes a video signal picked up by an image pickup device to increase the image magnification of a subject. A video camera provided with an electronic zoom means for changing the magnification and an optical zoom means for fixing at least the first lens unit on the subject side to the lens barrel and performing focus adjustment by moving the master lens and focus correction at the time of changing the image magnification. At
In the vicinity of the tele end of the optical zoom means, the image magnification changing operation is performed by the optical zoom means and the electronic zoom means so that the overall image magnification changing speed is the image magnification near the wide end of the optical zoom means. The image magnification changing speed of the electronic zoom means is controlled so as to be equal to the changing speed, and in a region where the focal length is longer than the tele end of the optical zoom means, the electronic zoom means is operated independently to perform the optical zoom. A control means is provided for controlling the image magnification changing speed of the electronic zoom means so as to be equal to the image magnification changing speed near the wide end of the means.

In order to achieve the above second object, the video camera according to the second invention is an electronic zoom means for electronically processing a video signal picked up by an image pickup device to change the image magnification of an object. And at least a first lens unit on the object side is fixed to a lens barrel, and an optical zoom unit for performing focus adjustment and focus correction at the time of image magnification variation by moving a master lens, wherein the optical zoom unit is provided. In areas other than the area before and after the tele end of the optical zoom means, the optical zoom means or the electronic zoom means is controlled so as to maintain the image magnification changing speed in the vicinity of the wide end of the optical zoom means. When switching between the image magnification changing operation by the optical zoom means and the image magnification changing operation by the electronic zoom means at the telephoto end, the original optical zoom means or the electronic zoom means is used. The image-magnification changing speed of the means is gradually decreased, and the electronic zoom means or the optical zoom means of the switching destination inherits the image-magnification changing speed at the time of switching and gradually reduces the image-magnification changing speed. The zoom lens is provided with control means for controlling so as to increase to the image magnification varying speed near the wide end.

[0027]

According to the control means of the first aspect of the invention, near the telephoto end of the optical zoom means, the image magnification changing operation is performed by the optical zoom means and the electronic zoom means so that the overall image magnification changing speed is the optical zoom means. The image magnification changing speed of the electronic zoom means is controlled so as to be equal to the image magnification changing speed in the vicinity of the wide end. That is, near the tele end of the optical zoom means,
While reducing the image magnification changing speed of the optical zoom means to avoid blurring, the electronic zooming means compensates for the slowing down of the image magnification changing speed of the optical zoom means as a whole. Maintains high-speed image magnification variation speed near the wide end.

Further, the control means of the first aspect of the invention is such that, in a region where the focal length is longer than the tele end of the optical zoom means, the electronic zoom means is operated independently to change the image magnification near the wide end of the optical zoom means. The image magnification changing speed of the electronic zoom means is controlled so as to be equal to the speed. As a result, it is possible to prevent blurring in the vicinity of the tele end of the optical zooming device and to maintain a high image magnification varying speed over the entire controllable focal length.

The control means of the second invention is such that the optical zoom means maintains a high image magnification changing speed near the wide end of the optical zoom means in the area other than the area before and after the tele end of the optical zoom means. Alternatively, the electronic zoom means is controlled. When switching the image magnification changing operation by the optical zoom means and the image magnification changing operation by the electronic zoom means at the tele end of the optical zoom means, when changing the image magnification of the switching source or the electronic zoom means, The speed is gradually decreased, and the electronic zoom means or the optical zoom means of the switching destination inherits the image magnification changing speed at the time of the change and gradually changes the image magnification changing speed in the vicinity of the wide end of the optical zoom means. The control is performed so as to increase to the high-speed image magnification variable speed of.

Therefore, when the optical zoom control and the electronic zoom control are switched, an unnatural image does not occur, blurring does not occur near the tele end of the optical zoom means, and the zoom speed is also in the electronic zoom control area. The zoom operation does not reduce the.

[0031]

The first and second embodiments of the present invention will be described below with reference to the drawings. It should be noted that both the first and second embodiments are shown in FIG.
5 is an example of a video camera that employs a zoom lens system that is compact and lightweight and has a large zoom magnification, which is a combination of the optical zoom system 1 shown in FIG. 5 and the electronic zoom circuit 50 shown in FIG. Since the configuration and operation of the electronic zoom circuit 50 itself have already been described, the description thereof will be omitted here. Further, the control of the optical zoom system 1 and the electronic zoom circuit 50 described below is performed by a microcomputer (not shown) mounted on the video camera.

[First Embodiment] FIG. 1 is a diagram showing a control state of a zoom speed corresponding to a change of a focal length in the first embodiment of the present invention. FIG. Speed, (B) shows the zoom speed of the electronic zoom circuit 50, and (C) shows the zoom speed when the optical zoom system 1 and the electronic zoom circuit 50 are used together.

Region 1 in FIG. 1 is a zoom region from the wide end to just before the zoom speed becomes slow near the tele end, and region 2 is a region from the zoom magnification to the tele end where the zoom speed becomes slow near the tele end, Area 3 is an area from the image magnification switched from the optical zoom system 1 to the electronic zoom circuit 50 to the maximum magnification of the electronic zoom circuit 50.

As is apparent from FIG. 1, in the first embodiment, in the area 1, the electronic zoom circuit 50 sets the zoom speed to "0" (fixed at the enlargement ratio of 1), and the optical zoom system 1 sets the wide range. Zoom operation is performed at the same high zoom speed as near the edges.

Next, in the area 2, the optical zoom system 1
Gradually reduce the zoom speed of. This avoids blurring of the subject image near the tele end of the optical zoom system 1. In this area 2, the electronic zoom circuit 50 gradually increases the zoom speed, and the electronic zoom system 1
The total zoom speed by the electronic zoom circuit 50 and the electronic zoom circuit 50 is made equal to the high zoom speed in the area 1.

In the area 3, since the electronic zoom circuit 50 is switched to the electronic zoom circuit 50 at the tele end of the optical zoom system 1, the zoom speed of the optical zoom system 1 is set to "0" (fixed to the maximum magnification). The zoom operation is performed by the electronic zoom circuit 50 such that the zoom speed becomes the same as the high zoom speed in the vicinity of the wide end of the optical zoom system 1 to reach a predetermined maximum enlargement ratio.

As described above, in the first embodiment, in the vicinity of the tele end of the optical zoom system 1, the zoom operation by the optical zoom system 1 and the zoom operation by the electronic zoom circuit 50 are simultaneously performed, so that the overall zoom speed is increased. Control the zoom speed of the zoom operation by the electronic zoom circuit 50 so that the zoom speed becomes equal to the high zoom speed near the wide end of the optical zoom system 1, and after the tele end of the optical zoom system 1, the electronic zoom circuit 50 is controlled.
The zoom speed of the electronic zoom circuit 50 is controlled so as to be equal to the high zoom speed in the vicinity of the wide end of the optical zoom system 1 only.

That is, as a whole zoom operation by the optical zoom system 1 and the electronic zoom circuit 50, the same high zoom speed as that in the vicinity of the wide end of the optical zoom system 1 is always maintained, and in the vicinity of the tele end of the optical zoom system 1. There is no blurring. In other words, a smooth and high-speed zoom operation is performed in all focal length regions corresponding to the optical zoom system 1 and the electronic zoom circuit 50.

[Second Embodiment] FIG. 2 is a diagram showing the control state of the zoom speed corresponding to the change of the focal length in the second embodiment of the present invention. (A) shows the zoom of the optical zoom system 1. Speed, (B) shows the zoom speed of the electronic zoom circuit 50, and (C) shows the zoom speed when the optical zoom system 1 and the electronic zoom circuit circuit 50 are used together.

Region 1 in FIG. 2 is a zoom region from the wide end to just before the zoom speed becomes slow near the tele end, and region 2 is a region from the zoom magnification to the tele end at which the zoom speed becomes slow near the tele end. The area 3 is an area from the image magnification switched from the optical zoom system 1 to the electronic zoom circuit 50 until the magnification of the electronic zoom circuit 50 reaches a predetermined value, and the area 4 is the area where the magnification of the electronic zoom circuit 50 is the above. It is an area from a predetermined value to the maximum magnification.

As is apparent from FIG. 2, in the second embodiment, in the area 1, the electronic zoom circuit 50 sets the zoom speed to "0" (fixed at the enlargement rate of 1) and the optical zoom system 1 sets the wide range. Zoom operation is performed at the same high zoom speed as near the edges.

Next, in the area 2, the optical zoom system 1
Gradually reduce the zoom speed of to prevent blurring. In this area 2 as well, the electronic zoom circuit 50 remains at the zoom speed "0" (fixed at the enlargement ratio of 1).

In the area 3, the electronic zoom circuit 50 is switched to the electronic zoom circuit 50 at the tele end of the optical zoom system 1, so that the zoom speed of the optical zoom system 1 is set to "0" (fixed to the maximum magnification). Is
Initially, the zoom speed near the tele end of the optical zoom system 1, that is, the zoom speed of the optical zoom system 1 at the time of switching is maintained, and then gradually becomes equal to the high-speed zoom speed near the wide end of the optical zoom system 1. The zoom speed of the electronic zoom circuit 50 is controlled so as to change as described above.

In area 4, the zoom speed of the optical zoom system 1 is set to "0" (fixed to the maximum magnification) as in area 3.
As it is, the electronic zoom circuit 50 performs the electronic zoom operation at the same high zoom speed as the zoom speed in the vicinity of the wide end of the optical zoom system 1, and reaches a predetermined maximum enlargement ratio.

As described above, in the second embodiment, when switching to the electronic zoom circuit 50 at the tele end of the optical zoom system 1, the electronic zoom circuit is maintained while maintaining the zoom speed near the tele end of the optical zoom system 1. Since the zoom operation by 50 is started, that is, the zoom speed is smoothly taken over, it is possible to prevent the appearance of an unnatural image. Then, after that, the zoom speed of the electronic zoom circuit 50 is controlled so as to gradually change to a high zoom speed near the wide end of the optical zoom system 1.

With such control, when the optical zoom system 1 is switched to the electronic zoom circuit 50, an unnatural image does not occur, blurring does not occur near the tele end of the optical zoom system 1, and electronic Even during zooming by the zoom circuit 50, the zoom operation is performed so that the zoom speed does not decrease.

[0047]

As described above, according to the first aspect of the present invention, it is possible to realize a smooth and high-speed zoom operation over the entire control range of the optical zoom control and the electronic zoom control. .

Further, according to the second invention, an unnatural image is not generated when the optical zoom control and the electronic zoom control are switched, and blurring does not occur near the tele end of the optical zoom means. Even in the electronic zoom control area, it is possible to realize a zoom operation that does not reduce the zoom speed.

[Brief description of drawings]

FIG. 1 is a diagram showing a zoom speed control state corresponding to a change in focal length in a first embodiment of the present invention.

FIG. 2 is a diagram showing a zoom speed control state corresponding to a change in focal length in a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a rear focus zoom type lens system.

FIG. 4 is a diagram showing a control state of a zoom speed corresponding to a focal length in a conventional rear focus zoom system lens system.

FIG. 5 is a block diagram showing an electronic zoom circuit.

FIG. 6 is a time chart showing scanning timing of the image sensor.

FIG. 7 is a conceptual diagram showing an image when the image magnification is enlarged.

FIG. 8 is a diagram showing a conventional zoom speed control state corresponding to a change in focal length when optical zoom control and electronic zoom control are used together.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical zoom system 3 ... Zoom lens 3 6 ... Master lens 7 ... Zoom motor 8 ... Focus motor 9 ... Zoom encoder 10 ... Focus encoder 12 ... Lens control microcomputer 13 ... Image sensor 21 ... Scan timing pulse generation means 22 ... Correlation 2 Double sampling circuit 23 ... AGC circuit 24 ... AD converter 25 ... Signal processing circuit 26 ... Memory circuit 27 ... DA converter 50 ... Electronic zoom circuit

Claims (2)

[Claims] 1. An electronic zoom means for varying the image magnification of a subject by electronically processing a video signal picked up by an image pickup element, and at least a first lens group on the subject side fixed to a lens barrel. In a video camera provided with an optical zoom means for performing focus adjustment and focus correction at the time of changing the image magnification by moving a master lens, in the vicinity of a tele end of the optical zoom means, the optical zoom means and the electronic zoom means are provided. Image magnification changing operation is performed to control the image magnification changing speed of the electronic zoom means so that the overall image magnification changing speed becomes equal to the image magnification changing speed near the wide end of the optical zoom means. In a region where the focal length is longer than the telephoto end of the optical zooming means, the electronic zooming means is operated independently so as to equalize the image magnification varying speed near the wide end of the optical zooming means. Video camera characterized by comprising a control means for controlling the image magnification varying speed of the electronic zooming unit. 2. An electronic zoom means for varying the image magnification of a subject by electronically processing a video signal imaged by an image sensor, and at least a first lens group on the subject side fixed to a lens barrel. In a video camera equipped with an optical zoom means for performing focus adjustment and focus correction at the time of changing the image magnification by moving a master lens, in a wide area of the optical zoom means other than an area before and after a tele end of the optical zoom means. The optical zooming means or the electronic zooming means is controlled so as to maintain the image magnification changing speed near the edge, and the image magnification changing operation and the electronic zooming by the optical zooming means at the tele end of the optical zooming means. When switching the image magnification changing operation by the means, the optical zoom means of the switching source,
Alternatively, the image magnification changing speed of the electronic zooming means is gradually decreased, and the electronic zooming means or the optical zoom means of the switching destination inherits the image magnification changing speed at the time of switching and gradually changes the image magnification changing speed. In addition, the video camera is provided with a control means for controlling so as to increase to an image magnification varying speed near the wide end of the optical zoom means.