JPS61251378A - Image pickup device - Google Patents

Abstract

PURPOSE:To easily see an image until it focuses on other subject when the object is moved to the other subject from the focusing time by providing an outline control means for changing an outline correcting characteristic according to an image forming condition by an optical system. CONSTITUTION:An automatic focus lens 1 is controlled by an automatic focus control circuit 16. Whether the lens 1 of a video camera focuses on an object is detected or not by a non-focusing detecting circuit 17, and its output signal is fed to a control circuit 18. By a command signal of the circuit 18, an APC compensation circuit (aperture compensation circuit) 12 is controlled so as to apply a stronger APC compensation when the lens 1 is not focused than when the lens 1 is focused. Therefore, on focusing on an object, when the lens 1 is turned to another object, an image is extremely easily seen in order to emphasize the outline of the image while the automatic focusing mechanism focuses.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an imaging device, and particularly to contour correction of an imaging device.

[Prior art]

Conventionally, in video cameras, in order to compensate for the deterioration of the frequency characteristics of video signals, an APC circuit (
The sharpness of the image is improved by correcting the outline using an aperture convention circuit.

However, these human PC correction methods operate so that the video camera is at an appropriate level when it is in focus (when it is in focus), and when it is out of focus (when it is not in focus). ), one image was extremely unsightly.

Particularly with autofocus video cameras, when one subject is in focus and you then point the camera at another subject, the screen may look unsightly until the autofocus is focused. was there.

〔the purpose〕

The present invention has been made in view of one or more problems of the prior art, and relates to an imaging device.

The object of the present invention is to provide an imaging device that can provide an easy-to-see screen even when out of focus.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 shows a block diagram of an embodiment of a video camera as an imaging device according to the present invention.

1 is an autofocus lens as an optical system, and 2 is an aperture.

3 is a relay lens, 4 is an imaging element as an imaging means, 5
is an operational amplifier, 6 and 8 are low-pass filters, 7 is a band-pass filter, 9 is a control circuit for the aperture 2, 10 is a brightness process circuit, 11 is a color separation circuit, 12 is an APC correction circuit, 13 is a color process circuit, 14 is a matrix circuit, 1
5 is an encoder, and 16 is an automatic focus control circuit for the lens 1. 17 is an out-of-focus detection circuit for detecting a state in which the lens 1 is out of focus, according to the principle of the present invention;
Reference numeral 18 denotes a control circuit which, together with the APC correction circuit 12, constitutes a control means for changing the degree of correction of the APC correction circuit 12 according to the output signal of the circuit 17.

Next, the operation will be explained. Autofocus lens 1.

The focus is controlled by an automatic focus control circuit 16.

In addition, the out-of-focus detection circuit 17 detects whether the lens 1 of the video camera is focused on the subject (in-focus) or not (out-of-focus), and its output is A signal is sent to the control circuit 18. This control circuit 18 controls the APC correction circuit 12 to apply stronger APC correction (APC correction) when the lens 1 is out of focus than when the lens 1 is in focus, in response to a command signal from the control circuit 18. Therefore, when one subject is in focus, when the camera (lens 1) is pointed at another subject, the image will change until the autofocus mechanism focuses. Since the contours are strongly emphasized, the image between them is much easier to see than in the conventional example.

FIG. 2 is a detailed explanatory diagram of the APC correction circuit 12 in FIG. 1. A is an input video signal, 19.20 is a delay circuit, 21.22 is each amplifier, and 23 is a gain kl of each amplifier 21, 22 according to a signal from the control circuit 18' in FIG. A switch circuit for switching to either one, 24a and 24b are subtracters.

25a and 25b are adders.

Next, the operation of APC correction will be explained with reference to FIG.

Eirin input signal A passes through delay circuit 19 to obtain signal B, and also passes through delay circuits 19 and 20 to obtain signal C.
8. , and B and C are processed by subtracters 24a and 24b, respectively.

The outputs from the definition multipliers are added by an adder 25a to obtain a contour signal, and are amplified by each amplifier 21, 22 to obtain a gain of .

These gains are switched by the switch circuit 23 in response to a command signal from the control circuit 18, and any one of the signals is added to the eight signals by the adder 25bK to output the video signal E.

That is, the gains k r , k of the amplifiers 21 and 22
By switching t, you can change the way APC correction is applied.

For example, if you set k>k, the switch 23 will be switched to the 1 side when in focus, and to the 2 side when out of focus, and the outline of the trap will be emphasized and the image will be easier to see when out of focus. can be obtained.

Next, a method for detecting the imaging state will be explained. FIG. 3 is a diagram illustrating the principle of a differential active autofocus system. In this system, the imaging state can be detected by the output of the out-of-focus detection circuit shown in FIG.

In Figure 3, LVix-cass lens, FM is the focal plane s'I l''2 are the light emitting lens and the light receiving lens, respectively, LT and PD are the light emitting element and the light receiving element, respectively, and o
s, os, os3 are the subject objects. Also the fourth
In the figure, 26a.

26b is each operational amplifier, 27a is an adder, 27b is a subtracter, and 28 is a determination circuit.

The light projecting element L°T in FIG. 3 projects a light spot image onto the objects OB1 to OB3. The light-receiving element PD outputs two types of signals depending on the receiving position of the reflected light. Control is performed depending on the magnitude relationship of the output, and two outputs are generated by forming an image on the focal plane FM. so that they are equal,
Focus lens L is activated. The out-of-focus detection circuit in FIG. 4 has two types of O outputs a and b of the light receiving element PD.
and the operational amplifier 26a, respectively.

26bK is amplified, and each output signal A, 8 is added/subtracted by an adder 27a and a subtracter 27b, respectively.
JIA-81/(A0B)c by the judgment circuit 28
7) Determine the level and perform APC correction 1 according to the level.
The purpose is achieved by changing the way 2 is multiplied. Namely.

When IA-81/(A+8) is larger than a predetermined level, it is determined that the object is out of focus.

Note that in this embodiment, the strength of the APC correction is determined by the two types of amplifiers 2 with + and kg in the two gains.
1.22 (Figure 3), but if two or more different amplifiers are used, it is possible to finely change the way APC correction is applied depending on the degree of out-of-focus. Therefore, the image quality when out of focus can be further improved.

Note that in this embodiment, it is used as an imaging device.

Although a video camera is shown as an example, facsimile machines, copying machines, etc. are also included.

〔effect〕

As explained above, according to the present invention.

Since the camera is configured to change the degree of one-line enhancement depending on the image forming state of the optical system of the imaging device, it is extremely easy to see the image from the time of focus until the subject is focused on another object, such as when moving the subject to another object. We were able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a video camera according to the present invention, FIG. 2 is a detailed explanatory diagram of the personal computer correction circuit, and FIG. 3 is an explanatory diagram of a differential active autofocus system.
FIG. 4 is a diagram of an out-of-focus detection circuit. 1...Autofocus lens 4...Photographer 12...APC correction circuit 16...Autofocus control circuit 17. ...Out-of-focus detection circuit 18 ...Control circuit FM ...Focal plane L ...Focus lens O8, ~08.
...Subject Object PD...Photo-receiving element Fig. 3

Claims (1)

[Claims] An imaging means for converting an optical image into a video signal; an optical system for forming an optical image on the imaging means; An imaging device comprising: contour control means for changing correction characteristics.