JPS63174476A - Automatic focusing device - Google Patents

Abstract

PURPOSE:To reduce time of focusing by detecting high frequency component from a video signal which scans a local area in a screen and executing actions for focusing so as to make the high frequency component the maximum. CONSTITUTION:A picture signal, picked up by a solid-state image pickup element 7 and converted into an electrical signal, is transmitted to a signal process part 4 through an amplifier 3. The high frequency component of the picture in a present location of a lens in the partial area mXn elements in the screen is computed in the signal process part 4. With sequentially altering the location of the lens 1, the high frequency component of the partial area of the picture is computed every time and the lens 1 is made to be moved to a spot where the maximum value of the high frequency component is obtained. thus, focusing can be executed in a short time by using a TV camera. It will do to move the image pickup element instead of moving the lens.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic focusing device using a video signal from a TV camera of an industrial visual device.

2. Description of the Related Art A case will be described with reference to FIG. 7 in which an automatic focusing device is configured using a video signal in a visual device using a conventional standard TV type area type image pickup device.

The optical image projected by the lens 1 is converted into a video signal by the image sensor 2, amplified by the amplifier 3, and this video signal is input to the signal processing section 4. The signal processing unit 4 detects high frequency components from the video signal on the screen.

The control unit 5 controls the actuator 6 to move the lens 1 in the optical axis direction, and determines the amount of high frequency components detected by the signal processing unit 4. FIG. 8 shows the relationship between the position of the lens 1 and the amount of high frequency components on the screen obtained corresponding to the position. On a screen that is in focus, the outline of the image will be the clearest, and the high-frequency components in the video signal for that screen will also be the largest. In FIG. 8, when the lens is at position Pf, it is a focused point and the maximum value is obtained.

Figures 8 and 9 show the operation of the automatic focusing device with the configuration shown in Figure 7.
This will be explained with a diagram. FIG. 9 shows the details of control by the control section 5.

In Figure 8, if the current position of the lens is Pl, detect the high frequency component of the screen at that position, then move the position of lens 1 a little and repeat the same operation. It can be confirmed that the amount of high frequency components exceeds the maximum value FM.After checking, the position of the lens 1 is returned to the position Pf where the maximum value FM was obtained.This position is the in-focus position.

3.-7 Problems to be solved by the invention When performing the above-mentioned operation, if a conventional solid-state image sensor is used, since it complies with the TV standard, it is standard to obtain a video signal for one screen. requires 33 m5, and the video signal of a local area of the screen can similarly only be obtained in a cycle of 33 mB. In FIG. 3, if the number of loops at the focal point 1 is N, the time required is at least 33m5XN, which is a problem in focusing in industrial visual equipment.

The present invention solves the above-mentioned conventional drawbacks and speeds up focusing.

Means for Solving the Problems In order to achieve the above object, the automatic focusing device of the present invention includes a lens that projects an image onto an image sensor, and a system that not only performs standard TV scanning but also repeatedly scans only a specific local area within the screen. an image leakage element that can switch this operation mode externally, an amplifier that amplifies this video signal, a signal processing section that detects the in-focus point from the video signal, and a lens that drives the lens based on this result. It is composed of an actuator.

Effects According to the above configuration of the present invention, there is a mode in which the focusing operation is performed at high speed, and it is very useful because it can realize the focusing operation of an industrial visual device at high speed.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 6.

FIG. 1 is an overall configuration diagram of the embodiment. In FIG. 1, 1 is a lens, 7 is a solid-state image sensor that is equipped not only with standard TV scanning but also with a mode of repeatedly scanning only a specified local area within the screen, and whose operation mode can be specified and switched from the outside. 3 is an amplifier, 4 is a signal processing section, 6 is a control section, 6
moves lens 1 using an actuator.

The operation of the automatic focusing device configured as described above will be explained below. FIG. 2 is a diagram showing the principle of construction of the image sensor. The image pickup device includes a photodiode 20, a vertical transistor 21, a horizontal transistor 5 base 22, and a vertical signal line 23. Consists of a horizontal signal line 24°25, an X scanner s, a Y scanner 9, an X scanner s, a Y scanner 9
has a programmable structure, and the location of local area scanning within the screen is determined by external settings. FIG. 3 is a detailed structural diagram of the X'scanner 8. In FIG. 3, the photodiode 20 corresponding to one scanning line is a horizontal transistor 22.
It is connected to the horizontal signal line 24 via. This horizontal transistor 22 is controlled by a shift register 10 driven by a horizontal clock, and is configured to scan in the horizontal direction by sequentially turning on. FIG. 4 shows details of the operation setting register of the X scanner 8. In the external shift scan start position register 11 (hereinafter abbreviated as start register), set "1°" to the point at which scanning in the X direction starts and all other values to "0".The contents of this start register 11 are directly transferred to the shift register 10. Therefore, the X scan starts from the position where 1'' is set. A scan width register 12 is a register that determines the scan width from the scan start position. Scanning is performed from the starting point by the value of the scanning width register 61, -;12, and this operation is automatically repeated thereafter. When the values shown in FIG. 4 are set for the scan start position register 11 and the scan width register 12,
The X direction scan starts from i and ends at i+5. FIG. 5 shows this operation as a time chart, and FIG. 6 shows it on the screen. Although the X-scanning operation has been explained above, Y-scanning can also be realized with a similar configuration. In this way, the local area 13 is
to obtain a video signal. This video signal is processed by the signal processing section 5.
The calculation is performed for the entire screen using a bypass filter of 3×3 pixel size. The high frequency component F of the screen is calculated using the following formula.

SX:CPi+1. j〒1 +Pi+1. j”−”i+
1. j+1)-CP, +p, ,4-p・
)1-1.1-1 1-1.1 1-1. )+l
5Y=(Pi-1, j+1+Pi, j+1+Pi+1.
j+1)-(Pi-1,j-1@-Pi=1.-,,+
pi-, , -1) The time required for this calculation is determined by the signal processing unit 5, which is composed of hardware with the calculation function shown in equation (1), ) The calculation time for the equation is 5'12 x 480 pixels for the entire screen and m x n pixels for the local area, and the high frequency components of the image at the current position of the lens 1 can be calculated in a short time. In this way, by sequentially moving the position of the lens 1 and calculating the high frequency component F of the local area of the image each time, as shown in FIG. 8, by moving the lens 1 to the location where the maximum value of the high frequency component F is obtained, Focusing can be done in a short time using a TV camera. Also, although not explained in detail, similar focusing can be achieved by moving the position of the image sensor instead of moving the lens.

Effects of the Invention As described above, according to the present invention, an image sensor that scans a local area within a screen, a signal processing unit that detects a high frequency component of the local area using the scanned video signal, and a detected high frequency component. Since the focusing operation is performed by a control section that controls the lens so that the lens is maximized, the time at the focusing point 1 is shortened.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an automatic focusing device according to an embodiment of the present invention, FIGS. 2, 3, and 4 are a configuration principle diagram and a specific circuit diagram of an image sensor, and FIGS. 5 and 6 are the same. Operation explanatory diagram, 7th
The figure shows a configuration diagram of a conventional autofocus device using a TV camera.
8 and 9 are diagrams of the operating principle of FIG. 7. 1...Lens, 3...Amplifier, 4...
...Signal processing unit, 5...Control unit, 6...
...Actuator, 7...Solid-state image sensor, 1o...Shift register, 11...
- Scan start position register. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
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Figure 6 1" Figure 8 Recos'I'fL Temple 4 Figure 9

Claims (1)

[Claims] A lens that projects an image, a solid-state image sensor that repeatedly scans an arbitrary local area within a screen, a signal processing unit that extracts a high frequency component of a video signal, a control unit that determines an increase or decrease in the high frequency component, and the control unit an actuator that moves the lens or solid-state image sensor according to a command from the autofocus device.