JPS6145684A - Image pick-up device - Google Patents

Abstract

PURPOSE:To generate a continuous picture without stop of an output signal by outputting an video signal from an video memory at the time of changing over a zoom part in an image pick-up device having plural zoom lenses different in variable power section. CONSTITUTION:Light from an object 1 is inputted through a focusing lens part 2 and a low scale factor zoom 3 (or high scale factor zoom part 3') to an image element 8 and is set to a television picture signal at a video signal processing circuit 12. The signal is stored to an image memory 13 and also outputted to a video signal change-over circuit 15. A scale factor setting circuit 11 changes a scale factor of the zoom part 3 (or 3') by a motor 9 and when a variable power section is changed, the zoom part 3 is changed over to the zoom part 3'. At the time of changing over the zoom part, the output of the image pick-up element 8 will not occur, but, during this period a video signal is outputted from the image memory 13 through a signal change-over circuit 15. Then, the output signal is not stopped. Since the zoom part is divided, a zoom lens can be miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an imaging device that temporally continuously outputs a high-resolution video signal over the entire range of magnification.

(Prior Art) In an imaging device, when an object is imaged on an image sensor surface by a lens optical system, a zoom lens having a variable power function is used to change the magnification of the image.

When a zoom lens is used, the magnification can be increased or decreased by relatively moving some of the lenses in the lens system and changing the focal point distance. However, when the magnification increases to 3x or more, lens aberrations increase,
Therefore, deterioration of resolution occurs. Therefore, in order to increase the magnification and reduce lens aberrations, the number of lenses in the zoom section was increased1), and a structure called a double zoom, where one zoom lens has two zoom sections, was adopted. This improves the characteristics of the lens. Also,
In order to widen the range of variable power of the zoom lens, it is equipped with several zoom lenses with different variable power ranges, and these several lenses are converted into a turret type according to the size of the image to widen the range of variable power. There are some.

(Problems to be Solved by the Invention) FIG. 3 shows examples of amplitude modulation rates of a conventional zoom lens for broadcasting business and a zoom lens for portable use.

Here, the vertical axis is the amplitude modulation rate for a sine wave input, and the horizontal axis is the resolution expressed in units of the number of TVs. Particularly high resolution characteristics are required of zoom lenses used in current image pickup apparatuses for use in broadcasting and the like having an image pickup surface of 273 inches to 1.25 inches. The solid line in FIG. 3 shows an example of the characteristics of a zoom lens for broadcasting business, which exhibits very good resolution characteristics of 14 times by relatively moving a portion of the zoom lens. As the solid curve shows, the resolution is 1600T.
With V lines, the amplitude modulation rate in the lens imaging system has degraded to about 50%, and furthermore, due to the decrease in the amplitude modulation rate in the imaging device itself, the amplitude modulation rate of the video signal output itself is at a resolution of 1600.
It deteriorates to about 10% for TV books.

However, although zoom lenses for broadcasting work have good resolution,
It has the disadvantage of being heavy and large. Even a standard zoom lens with a zoom ratio of 10x weighs about 10 to 20 kg.
g, and the effective diameter of the front lens is approximately 170+n+nφ. Therefore, both in weight and size, the zoom lens and the main body of the imaging device are almost the same size, and the imaging device as a whole becomes very large.

On the other hand, the broken line in FIG. 3 shows an example of the characteristics of a standard 10x zoom lens, which is used in a high-resolution portable camera and also has a portion that moves relatively. 100 (
As a high-resolution signal used for high-definition television that requires a resolution of 1'r'V or more, the output of a video signal using a zoom lens of a portable camera, typically shown by the broken line in Figure 3, has a resolution of Very bad. A zoom lens used in a high-resolution portable camera exhibiting the characteristics shown by the broken line in Figure @3 weighs approximately 2 to 3 kg and has an effective front lens diameter of 70 mm.
mmφ, it is lighter and smaller than zoom lenses for broadcasting business. However, since the main focus of the design is to reduce the weight and shape, the resolution is poor and the characteristics are insufficient.

As mentioned in the introduction, lightweight and compact zoom lenses have a structure in which several zoom lenses can be exchanged, such as a turret type, or a part of the zoom lens can be replaced or removed. However, when changing the magnification using a zoom lens having such a structure, there is a problem in that the video signal is temporarily interrupted. Figure 4 shows how the magnification increases with time during shooting and changes when moving from one magnification range to another. td), there is no video output, and on the receiving side that reproduces the image, a discontinuous received image is output, giving an extremely unnatural feeling.

SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging device that is a high-resolution, relatively lightweight, and compact zoom lens that has a variable magnification function and that generates continuous images without interruption in the video output signal.

(Means for Solving the Problems) An imaging device according to the present invention includes a plurality of zoom lenses, each of which is assigned a different magnification range but is set continuously, and a zoom unit switching means for switching the zoom lenses. a determining means for outputting a signal for switching to a zoom lens corresponding to the magnification to the zoom section switching means and for outputting a signal for switching the video signal to the video signal switching means in conjunction with lens switching; An image sensor that converts an image passed through a lens into an electrical signal, a video signal processing circuit that generates a TV video signal from this electrical signal, a video memory that can write and read the TV video signal, and a signal from the above-mentioned determining means. In response to this, when scaling an image within each scaling interval, a real-time television video signal is output from the video signal processing circuit, and when scaling an image over two or more scaling intervals, , a video signal switching means for outputting a television video signal from the video memory at the time of section switching, and the video memory interpolates interruptions in the video signal output due to switching of the zoom lens.

(Function) According to the present invention, each variable magnification section can be made smaller by the design of dividing the variable magnification section of the zoom lens, so that a high resolution zoom lens with a high amplitude modulation rate can be used over the entire variable magnification section. can get. By interpolating the video signal output that temporarily disappears when changing the magnification section with the video signal from the video memory circuit of the imaging device, it becomes a continuous video signal output, so there is no unnaturalness on the receiving side. It is possible to continuously change the zoom magnification without giving any noticeable effect.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an embodiment of the invention.

Object 1 is a subject to be imaged. 7 of zoom lenses
A focusing lens section 2 is provided in front of the zoom section 3 or 3'. (Zoom lenses usually use lens parts with large apertures.) The two zoom sections 3, 3' each handle a different magnification change section. zoom lens 3
．． In the case of 3.3, part or all of the lens is replaced or detached as a means of changing magnification. In the following explanation, it will be assumed that the zoom section 3 is in charge of a low magnification section and the zoom section 3'' is in charge of a high magnification section. Variation lenses 4 and 4' and suspension lenses 5 and 51 are housed inside the cylinders of the zoom units 3 and 3, respectively. The variation lenses 4, 4' are for changing the zoom ratio, and the enhancement lenses 5, 5' are for reducing the amount of aberration. Using the relay lens 6, an image 7 of the object 1 is formed on the surface of the image sensor 8. Zoom section 3
゜3゛ includes a motor 9 for changing the magnification, transmission components such as gears and cams, and switching of the variable magnification section.
The driving force for zooming within the section is transmitted.

A magnification setting circuit 11 that sets the magnification of the zoom lens provides the motor 9 with a magnification interval switching command and a magnification changing command within the interval.

The optical image is photoelectrically converted into an electrical signal by the image sensor 8, and then γ-corrected by the video signal processing circuit 12.

Shading correction, knee correction, etc. are added, and sync signals and burst signals are also added to create a television video signal. This television video signal is stored in a video memory circuit 13 such as COD or CMO8. The magnification setting signal sent from the magnification setting circuit 11 to the motor 9 is sent to the switching determination circuit 14.
Also sent to.

The switching determination circuit 14 determines whether or not to change the magnification range of the zoom lens, and outputs the result to the video signal switching circuit 15. The video signal switching circuit 15 selects whether to take a signal from the video signal processing circuit 12 or from the video memory circuit 13 as a video signal output based on the signal from the switching determination circuit 14, and outputs the video signal for zooming. Outputs continuously regardless of the switching of the variable magnification section.

FIG. 2 shows the progress of changing the magnification section and the signals sent to the video signal switching circuit 15 in this embodiment. Second
Figure (a) shows the passage of time when changing the magnification M of the image while switching from the magnification changing section of the zoom section 3 (zoom magnification Z,) to another zoom section 3' (zoom magnification Z3'). A zoom magnification is specified by a zoom lens magnification setting circuit 11.

In the zoom lens switching determination circuit 14, a magnification threshold is set for each magnification change section. For example, at t=ta, the zoom unit 3 increases the zoom magnification Z3 and sets the threshold value Tl.
+3, and the magnification is being set in the increasing direction, and the video signal switching signal V is set as shown in FIG. 2(b). n pulses are generated. This video signal switching signal V. 0, the video signal switching circuit 15 outputs the signal from the video memory circuit 13 as a video signal output. The magnification change by the zoom unit 3 continues for a while after La.
The magnification change by the zoom unit 3 ends at t=tb. t a short time after tb. Until then, the zoom section switching signal i is shown in FIG. 2(c). 11 is applied to the motor 9, and at 2 to 2, the zoom section is switched to 3. From 1°, the magnification is changed by the zoom section 3. At t: td, the zoom section 3
As shown in FIG. 2(d), the video signal switching signal V has reached the threshold value Th,' and the magnification is increasing. A pulse of ff is generated by the switching determination circuit 14.

This ■. In response to the ff signal, the video signal switching circuit 15 outputs an online signal from the video signal processing circuit 12 as a video signal output.

Therefore, despite the zoom lens switching due to magnification change, the video signal V remains unchanged as shown in FIG. 2(e).

is output without interruption even between ta and td.

In this example, a structure in which the variable magnification section is divided into two is shown, but if the entire variable magnification range is wide, high resolution can be maintained at any magnification by dividing it into two or more. . In addition to zoom lenses, there are also
Of course, it is also possible to use a variable magnification optical system commonly called an extension, which changes magnification by converting a part of the lens.

(Effects of the Invention) According to the present invention, even a portable camera having a small imaging device main body for processing signals can be small, lightweight, inexpensive,
Moreover, for the broadcasting industry i shown by the solid line in Figure 3! - It is possible to provide an imaging device equipped with a zoom lens with higher performance than that of a zoom lens.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the invention. FIGS. 2(a) to 2(e) are time charts showing the elapsed time of scaling interval switching and the continuity of video signals. FIG. 3 is a graph showing the amplitude modulation rate of a conventional zoom lens for broadcast running (solid line) and a zoom lens for portable use (broken line). FIG. 4 is a time chart showing the process of zooming when using a conventional turret type or partially interchangeable type zoom lens.

Claims (1)

[Claims] (1) A plurality of zoom lenses each having a different magnification range but set continuously, a zoom section switching means for switching the zoom lenses, and a zoom section that sends a signal for switching to the zoom lens corresponding to the magnification. a determining means for outputting a signal to the switching means and for switching the video signal in conjunction with lens switching to the video signal switching means; an image sensor for converting an image passed through a selected zoom lens into an electrical signal; A video signal processing circuit that generates a TV video signal from this electrical signal, a video memory that can write and read the TV video signal, and a video memory that receives signals from the above-mentioned determining means and changes the size of the image within each scaling section. In this case, the video signal processing circuit outputs a real-time television video signal, and in the case of changing the scaling of the image over two or more scaling sections, the video signal processing circuit outputs the television video signal from the video memory when changing the scaling section. What is claimed is: 1. An imaging device comprising: a signal switching means, the image capturing device interpolating interruptions in video signal output due to switching of a zoom lens using a video memory.