JPH05308552A - Camcorder - Google Patents

Abstract

(57) [Abstract] [Purpose] In a camcorder, by displaying focusing information in the MF control mode, the operation for focusing is facilitated and the focusing time is shortened. A control data creation circuit 15 creates AF data corresponding to the level of a high frequency component of a video signal of a subject, and a focus direction determination unit 10c of the microcomputer 10 detects the focus information to detect the focus information. Control signal is output to. The character generator 16 generates a pattern signal indicating focus information based on this control signal.
This pattern signal is combined with the output signal of the video circuit system 6 by the combination circuit 17, and is displayed on the EVF 8 via the EVF drive circuit 7. The user looks at the focus information displayed on the EVF 8 and then determines how to operate the MF ring 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for displaying focus information during manual focusing in a camera-integrated VTR (hereinafter referred to as a camcorder) having an autofocus function.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing the structure of a conventional camcorder. In the figure, an image of a subject (not shown) transmitted through the focus lens 1 is an image pickup device 2 such as a CCD.
Is converted into a digital video signal by the A / D conversion circuit 5 via the sample and hold circuit 3 and the AGC amplifier 4 and output to the video circuit system 6. The video circuit system 6 creates an NTSC signal and a recording signal based on the digital video signal output from the A / D conversion circuit 5. An output signal of the video circuit system 6 is converted into a signal for driving an EVF 8 composed of a liquid crystal panel or the like by an electronic viewfinder (hereinafter referred to as EVF) drive circuit 7 and applied to the EVF 8.

Manual focus (hereinafter referred to as MF
An electric signal (hereinafter referred to as MF data) Dm corresponding to the rotation direction and the rotation amount of the ring 9 is input to the microcomputer 10. The drive direction determination unit 10a in the microcomputer 10 detects the rotation direction and the rotation amount of the MF ring 9 from the MF data Dm, and the motor drive instruction unit 10b is the motor drive circuit 1
A drive control signal corresponding to the rotation direction and the rotation amount of the MF ring 9 is output to 1. The motor drive circuit 11 rotates the motor 12 based on the drive control signal, and the lens support member 1 is moved by a distance corresponding to the rotation direction and the rotation amount of the MF ring 9.
Move 3 The drive direction determination unit 10a and the motor drive instruction unit 10b in the microcomputer 10 are functional blocks.

FIG. 5 is a flowchart of the MF control operation of the microcomputer in the conventional camcorder. The MF operation in the conventional camcorder will be described below with reference to FIGS. 4 and 5. First, when the user rotates the MF ring 9 in a predetermined direction by a predetermined amount, the microcomputer 10 takes in the MF data Dm (S21).

The microcomputer 10 looks at the MF data Dm and determines whether it is data for instructing to move the focus lens 1 forward, data for instructing it to move backward, or stopping at the current position. It is determined whether the data is a command. Here, when Dm is a positive value, it is instructed to move forward, when it is negative, it is instructed to move backward, and when it is 0, it is data to instruct to stop at the current position. (S22).

If Dm> 0, a drive control signal for moving the focus lens 1 forward by Dm is output to the motor drive circuit 11 (S23), and if Dm <0, the focus lens 1 moves backward by -Dm. A drive control signal for causing it to be output to the motor drive circuit 11 (S24), and if Dm = 0, a drive control signal for stopping the motor is output to the motor drive circuit 11 (S25).

At this time, the user uses the MF ring 9 so that the image of the subject displayed on the EVF 8 is not out of focus.
The focus was adjusted by adjusting the rotation direction and the rotation amount of the.

[0008]

However, during the MF control of the conventional camcorder, the user rotates the MF ring to visually judge the out-of-focus state of the image displayed on the EVF and focus the image. It was necessary to move the focus lens in the opposite direction to the focus point, or to move the focus lens too far before returning. Therefore, there is a problem that it takes time to focus.

It is an object of the present invention to provide a camcorder that displays focusing information during MF control, thereby facilitating an operation for focusing and shortening the time.

[0010]

In order to solve the above problems, the present invention relates to a camcorder, a means for detecting focus information based on a video signal obtained by imaging a subject, and an output of the means. And a means for displaying a pattern indicating the focus information based on the pattern signal, so as to display the pattern indicating the focus information during MF control. Configured.

[0011]

According to the present invention, since the camcorder is configured as described above, when a subject is photographed in the MF control mode, if the pattern indicating the focusing information displayed by the arrow or the like in the EVF is seen, You can see the direction in which you want to move the ring, and you can see if you are in focus.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a camcorder according to an embodiment of the present invention. Here, FIG.
The same numbers are assigned to the parts corresponding to. Therefore, the process from converting an image of a subject (not shown) into a video signal by the image pickup device 2 and outputting the video signal to the video circuit system 6, the EVF drive circuit 7 drives the EVF 8 from the output signal of the video circuit system 6. The process of converting the signal into a signal and applying it to the EVF 8 and the process of moving the focus lens 1 according to the operation of the MF ring 9 are the same as those in the conventional example shown in FIG.

Next, the autofocus (hereinafter referred to as AF) control in this embodiment will be described. First, the principle of AF control in this embodiment will be briefly described. In the present embodiment, the level Df of the high frequency component of the video signal of the subject when the focus lens 1 is wobbled (vibrated) back and forth from the state where it is stopped at a predetermined position and is displaced forward.
And the level Db of the high frequency component of the video signal of the subject when displaced to the rear are compared, and the focus lens 1 is moved by a predetermined distance in the direction in which the high frequency component is large. Then, the same operation is repeated again at that position. The high frequency component increases as it approaches the in-focus point and becomes maximum at the in-focus point. Therefore, for example, the high-frequency component of the video signal of the subject when displaced forward and the high-frequency component of the video signal of the subject when displaced rearward. The in-focus point can be obtained by processing such as detecting a position at which is equal to each other, storing Df and Db for each operation of wobbling and moving the focus lens, and detecting a position at which it becomes maximum.

In FIG. 1, the wobbling control section 10g in the microcomputer 10 outputs a wobbling control signal to the motor drive circuit 11. This wobbling control signal has a cycle of, for example, 4 fields, the focus lens 1 is displaced forward in the first field, the focus lens 1 is stopped in the second field, and the focus lens 1 is displaced in the third field backward. Then, the fourth field is a control signal for stopping the focus lens 1. Each block in the microcomputer 10 is a functional block.

The control data creating circuit 15 creates AF data, automatic exposure (hereinafter referred to as AE) data, and the like. AF
The data is digital data corresponding to the level of the high frequency component of the video signal when the focus lens 1 is displaced forward as described above. There are various algorithms for detecting the level of the high frequency component, for example, there are various algorithms such as addition value calculation of the high frequency component for each horizontal scanning line, peak value calculation of the high frequency component in the center of the screen, etc. This may be arbitrarily selected. Further, there are various algorithms for detecting the AE data, such as calculation of average luminance in the central portion of the screen, which may be arbitrarily selected.

The focus direction determination unit 10c of the microcomputer 10 detects focus information (focus direction and focus position) from the level of the AF data created by the control data creation circuit 15, and the motor drive instruction unit 10d drives the motor. A drive control signal for instructing the circuit 11 to move the motor 12 in the focusing direction by a predetermined distance is output. At this time, the AF / MF switching unit 1
0e is set to the AF side by operating the AF / MF switching button 18. The motor drive circuit 11 rotates the motor 12 based on the drive control signal to move the lens support member 13 by a predetermined distance in the focusing direction.

FIG. 2 is a flowchart of the AF control operation of the microcomputer according to the embodiment of the present invention. The AF control operation in this embodiment will be described below with reference to FIGS. 1 and 2. First, the wobbling control unit 10g of the microcomputer 10 outputs a wobbling control signal to the motor drive circuit 11 to displace the focus lens 1 back and forth (S1). At this time, the video signal of the subject when the focus lens 1 is displaced forward and the video signal of the subject when the focus lens 1 is displaced rearward are input to the control data generation circuit 15. The control data creation circuit 15 uses a predetermined algorithm to determine the level Df of the high frequency component of the video signal of the subject when the focus lens 1 is displaced forward and the video signal of the subject when the focus lens 1 is displaced backward. The level Db of the high frequency component is detected.

Next, the microcomputer 10 takes in Df and Db (S2) and compares them (S3). And Df>
If it is Db, the focus is on the front side, so the drive control signal for instructing to move the focus lens 1 forward is output by the motor drive instructing section 10d (S5), and Df <
In the case of Db, since the in-focus point is behind, the drive control signal for instructing to move the focus lens 1 backward is output by the motor drive instructing section 10d (S5). If Df = Db, the focus lens 1 is located at the in-focus point, so a drive control signal for stopping the motor is output to the motor drive circuit 11.

Next, the present invention will be described in terms of displaying the focus information on the EVF by utilizing the AF data during the MF control. In the present embodiment, the focusing direction determination unit 1 of the microcomputer 10 is based on the AF data created by the control data creation circuit 15.
0c determines the focus direction and the focus position, and outputs a control signal corresponding to the focus information to the character generator 16. The character generator 16 generates a pattern signal indicating focus information based on this control signal. This pattern signal is combined with the output signal of the video circuit system 6 by the combination circuit 17, and is displayed on the EVF 8 via the EVF drive circuit 7. Here, a pattern of one circle and two triangles on both sides of the circle is displayed on the lower left portion of the screen of the EVF 8. For example,
If the focus lens 1 is configured to move forward when the MF ring 9 is rotated counterclockwise,
When the focal point is in the front, the left triangular pattern is selected, when the focal point is in the rear, the right triangular pattern is selected, and when the focus lens 1 is in the focal point, the circular pattern is selected. Furthermore, when the focus lens 1 is not in focus, a message such as "out of focus" may be displayed.

In the present embodiment, the illuminance determining unit 10f of the microcomputer 10 further outputs a control signal corresponding to the illuminance to the character generator 16 based on the AE data created by the control data creating circuit 15, so that the character generator 16 outputs the control signal. A pattern related to AE such as "the illumination is too dark to shoot" is generated. FIG. 3 is a flowchart of the MF control operation of the microcomputer in the embodiment of the present invention.
Hereinafter, M in the present embodiment will be described with reference to FIGS. 1 and 3.
The F operation will be described.

First, the user selects the AF / MF switching button 18
Is set to the MF side, the AF / MF switching unit 10e in the microcomputer 10 is switched to the MF side. In this state,
The wobbling control unit 10g of the microcomputer 10 sends a wobbling control signal to the motor drive circuit 11 as in the AF control.
To move the focus lens 1 back and forth (S
11). Then, the control data creation circuit 15 also uses a predetermined algorithm as in the AF control, and the level Df of the high frequency component of the video signal of the subject when the focus lens 1 is displaced forward and the focus lens 1 is displaced backward. At this time, the level Db of the high frequency component of the video signal of the subject at that time is detected.

Next, the microcomputer 10 takes in Df and Db (S12) and compares them (S13). And D
If f> Db, the in-focus point is in the front. Therefore, the character generator 16 outputs a control signal for generating a pattern (for example, a left triangle) indicating that the in-focus point is in the front (S14), and Df If <Db, the in-focus point is at the rear, so a control signal for generating a pattern (for example, a right triangle) indicating that the in-focus point is at the rear is output to the character generator 16 (S15).
If Df = Db, since the focus lens 1 is located at the focal point, a control signal for generating a pattern (center circle) indicating the focal point is output to the character generator 16 (S16).

The user can judge how to operate the MF ring 9 next by looking at the pattern indicating the focus information displayed on the EVF 8. The present invention is not limited to the above-described embodiments, and various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention. For example, wobbling of the focus lens may be performed using a piezo element.
Further, another autofocus control method using the output signal of the image sensor may be adopted. Furthermore, the pattern for displaying the focus information is not limited to the triangle and the circle, and may be arbitrary, or may be displayed to identify the distance from the focus point.

[0024]

As described above in detail, according to the present invention, since the focus information is displayed during the MF control, the focus lens can be moved in the opposite direction to the focus point, or the focus point can be changed. There is no need for operations such as returning after overshooting. Therefore, the operation for focusing becomes easy,
And the time to focus is shortened.

Further, since the in-focus state is evaluated by an electric value, it is possible to perform in-focus accurately and without blurring the screen.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a camcorder according to an embodiment of the present invention.

FIG. 2 is a flowchart of an AF control operation of the microcomputer according to the embodiment of the present invention.

FIG. 3 is a flowchart of an MF control operation of the microcomputer according to the embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional camcorder.

FIG. 5 is a flowchart of an MF control operation of a microcomputer in a conventional camcorder.

[Explanation of symbols]

 8 EVF 9 MF ring 10 Microcomputer 10c Focusing direction determination unit 15 Control data creation circuit 16 Character generator

Claims (1)

[Claims] 1. A unit for detecting focus information based on a video signal obtained by picking up an image of a subject, and a unit for generating a pattern signal indicating the focus information based on an output of the unit. And (c) a means for displaying a pattern indicating focus information based on the pattern signal, wherein the pattern is displayed during manual focus control.