JPH04151133A - Image pickup device - Google Patents

Abstract

PURPOSE:To enable focusing which is fast in speed and accurate by providing a front lens system and a rear lens system or an image pickup element mutually movably. CONSTITUTION:The front lens system 20 and rear lens system 23, or image pickup element 24 are provided mutually movably on the optical axis and focusing information is obtained by 1st focusing information systems 29 - 33 which obtain focusing information by measuring the distance of an object directly and 2nd focusing information systems 36 - 42 which obtain focusing information according to the high-frequency component of a video signal. Then when the focusing is carried out, at least one of the front lens system 20 and rear lens system 23 and image pickup element 24 is moved on the optical axis according to the focusing information from the 1st and 2nd focusing information systems. Consequently, the focusing speed is fast and the accurate focusing can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a video imaging device, and more particularly to an imaging device that has a high focusing speed and can perform accurate focusing.

(Prior Art) A video focusing method is one of the focusing methods for a video imaging device.

This method is based on the magnitude of high-frequency components contained in the video signal obtained through the imaging lens system and image sensor.
- This is a method of focusing by controlling the lens.

The principle of this method is that when the focus lens is moved back and forth, the horizontal axis is the imaging position, and the vertical axis is the magnitude of the high frequency component of the subject on the photoelectric conversion surface of the image carrier. The size of the high frequency component draws a mountain shape with the peak at the in-focus position,
The principle is to detect the direction of this mountain and focus at the top of the mountain.

There is also a method called an infrared focusing method.

This method projects infrared rays onto a subject and uses the reflection to perform focusing.

Furthermore, there is also a method called an ultrasonic focusing method.

In this method, an ultrasonic source emits ultrasonic waves to a subject, and the reflection time of the ultrasonic waves is measured to perform focusing.

(Problem to be solved by the invention) However, in the case of the video focusing method,
Since the video signal is used as the distance measurement signal for focusing, there is no cause for variation and the focusing accuracy is excellent. - It is vulnerable to focusing, and it takes time to detect the focusing direction because the lens is moved to focus without directly measuring the distance.

In addition, the infrared focusing method and the ultrasonic focusing method have a fast focusing speed because they measure the distance directly to the subject, and they use infrared or ultrasonic waves reflected from the subject, so they have a low focusing speed. Contrast focusing can be performed well, but on the other hand, it is weak when focusing on objects with low reflectance, long distance objects, oblique objects, or through glass, and it is difficult to focus on objects with low reflectance, long distance objects, oblique objects, or through glass. In the case of a type in which a detection means for detecting reflected lines, reflected waves, etc. is provided externally, there is a problem in that parallax occurs and the in-focus position shifts.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an imaging device that has a high focusing speed and can perform accurate focusing.

Means for Solving the Problems) In order to achieve the above object, the imaging apparatuses described in (1) to (3) below are provided.

<1) At least a front lens system on the optical axis, a variable magnification lens system for changing the magnification of the image light from the subject, a rear lens system for forming the imaging light, and the imaging light An imaging device comprising: an image carrier for extracting a video signal by nine-electroconversion using a photoelectric conversion surface; and a focusing information system to which focusing information from the subject is supplied; A ball lens system or the image element is further provided movable on the optical axis, and the focusing information is transmitted to a first focusing information system obtained by direct distance measurement of the object and to a high-frequency component of the video signal. a second focusing information system obtained based on the
- An imaging device characterized in that at least one of the front lens system, the rear lens system, or the image sensor is moved on an optical axis based on focusing information from a focusing information system. .

(2) The imaging apparatus according to claim (1), further comprising a switching means for selectively switching the focusing information from the first focusing information system and the second focusing information system. Imaging device.

(3) On the optical axis, there is at least a front lens system, a variable magnification lens system for changing the magnification of the imaging light from the subject, a rear lens system for forming the imaging light into an image, and a rear lens system for converting the imaging light into an image. An imaging device comprising: an imaging device that performs photoelectric conversion on a photoelectric conversion surface to extract a video signal; and a focusing information system based on a high-frequency component of the video signal; elements are provided so as to be movable relative to each other on the optical axis, and during focusing, the front lens system, the rear lens system, or the imaging device are simultaneously moved on the optical axis based on the focusing information. An imaging device that uses

(Operation) Focusing is performed by obtaining focusing information from a first focusing information system based on direct distance measurement of the subject and a second focusing information system based on high-frequency components of a video signal.

Further, focusing is performed by simultaneously moving the front lens system and the rear lens system or the imaging device on the optical axis using focusing information based on the high-frequency components of the video signal.

(Embodiment) FIG. 1 shows a schematic block diagram of an embodiment of the present invention.

A detailed explanation will be given below according to this embodiment.

Imaging light A from the subject M passes through a front lens system 20, a zoom lens system (variable magnification lens system) 21, and
Image sensor 24 via mirror 22 and rear lens system 23
is imaged, photoelectric conversion is performed within this image sensor 24,
This output signal is supplied to a video circuit 27 via an amplifier 25, where it is subjected to predetermined signal processing to become a signal that conforms to a video signal.

Reference numeral 29 denotes an infrared light source, and the infrared light emitted from this light source 29 is focused by a projection lens 30, bent in a right angle direction by a full-reflection mirror 31, and converted into imaging light A by a mirror 22 arranged in the next lens system. It is bent in a direction opposite to the direction of the long sword and at a position slightly away from the optical axis, passes through the zoom lens system 21 and the front lens system 20 sequentially, and is fired toward the subject M.

The infrared rays are reflected by this subject M, and the light receiving lens 32
The image is then focused on a light receiving element (silicon diode) 33.

This light-receiving element 33 is divided into two regions, and when the two regions are in just focus, a spot of reflected light is imaged at the center of the region boundary, and the output becomes equal.

If the focus is shifted to the front or rear position,
Unbalanced signals are output from the two areas.

That is, the loop from the light source 29 to the light receiving element 33 forms an infrared focusing information system (first focusing information system).

The output from the two areas is sent to the microcomputer 34.
The microcomputer 34 detects the output difference and generates a control signal based on the position information from the position sensors 44, 45, 46, and the drive circuit 36.4.
7, motors 37 and 48 move the front lens system 20 and the image sensor 24 in the direction of the focusing position on the optical axis to perform the first focusing operation.

At this time, in the microcomputer 34, the light receiving element 33
The focusing distance IIX value and Y value of the front lens system 20 and the image sensor 24 are immediately calculated based on the output signals from the front lens system 20 and the image sensor 24. In addition to the distance, the values obtained by multiplying the X value and Y value by 09 are generated as the control signal, and this signal is used to move the front lens system 20 and the image sensor 24 to the 90% focal point position. It is controlled to move quickly.

The movement distance of the front lens system 20 and the image sensor 24 is not set as the movement distance based on the in-focus position determined by the 81 calculation result of the microcomputer 34, but is set as the movement distance up to 90% of the movement distance, which has already been done in the conventional example. As mentioned above, it is expected that the focusing information will change due to the movement of the lens system, and that the focus position will shift due to the occurrence of vararax, so even if the microcomputer 34 calculates the focus position accurately, It is also conceivable that the front lens system 20 and the image sensor 24 may deviate from the normal focusing position and stop due to the above-mentioned causes, making it impossible to perform accurate focusing.

Therefore, the microcomputer 34 considers the error in advance, and first moves the front lens system 20 and the image pickup element 24 to a position where the error can be absorbed (90% of the in-focus position) as a focusing operation in the -th stage. , and as a second focusing operation, the image sensor 24 is moved to the in-focus position based on focusing information from a video focusing information system (details will be described later) to perform accurate focusing. It is configured to do this.

The arrangement is such that coarse focusing is first performed using information from the infrared focusing information system, and then fine focusing is performed using information from video focusing information.

The operation of the video focusing information system (second focusing information system) will be described in detail below.

The output signal from the amplifier 36 is branched here and supplied to a band pass filter (BPF) 38 to extract a predetermined high frequency component, and this output signal is supplied to a gain converter amplifier (GCA) 39 where When the focal voltage becomes low, the voltage is amplified and supplied to the next-stage area sensing circuit 41.

This area sensing circuit 41 extracts and detects the imaging area, and outputs it as a focal voltage to an A/D (analog-digital) converter 42 at the next stage.

This focus voltage is digitized by this A/D converter 42 and supplied to the microcomputer 34 as focus voltage information (focusing information).

This microcomputer 34 also has an image sensor 24.
Position information is supplied from a position sensor 44 that detects the position of the lens, and position information related to the focal length of the front lens system 20 and zoom lens system 2 is also supplied from other position sensors 45 and 46. ing.

The microcomputer 34 has the above A, -' [)
The converter 12 (the focal voltage accompanying the movement of the S-image element 24 in the optical axis direction) is sampled every field from the start of scanning, and is sequentially digitized and supplied. A differential voltage is calculated by sequentially comparing the levels of the focal voltages at the peak of the field, and the magnitude and sign change of the differential voltage are detected and the position sensor 44.4
The position information from 5.46 and the focus position are extracted, a control signal is generated based on this result, and the image sensor 24 is driven by driving the motor 48 via the drive circuit 47 based on this (S). is configured to move along the optical axis to the in-focus position.

50 is a drive circuit, and 51 is a zoom lens system motor.

At the same time, the microcomputer 34 determines, for example, that if the output signal from the light receiving element 33 of the infrared focusing information system is smaller than a preset value, the subject is far away or has a low reflectance. If it is determined that it is difficult to obtain focusing information from the subject due to the subject being oblique, or conversely, if the output signal is larger than the set value, a Y flag will be issued indicating that there is a failure in the focusing information system. 11! Then, the camera switches to use focusing information from the video focusing information system, and uses this information to move the front lens system 20 and the camera lens 24 to the in-focus position.

Historically, during the focusing operation of stage 1 (focusing synchronization based on the video focusing information system)), if the focal voltage suddenly deviates beyond a predetermined value during the focusing operation, it is determined that the video focusing information system is malfunctioning. If the focus voltage is less than the predetermined value because the focal point is small, or if the focal curve is smoother than the predetermined value because the subject is a low-contrast subject, there will be problems with focusing. Then, the camera switches to use 74-focusing information of the infrared focusing information system, and controls the image pickup device 24 to move to the in-focus position.

The reason why the structure is such that the image sensor 24 side is moved without moving the front lens system 20 during this second stage operation is to prevent deviations of the optical system due to changes in the angle of view, etc. There is no problem even if the front lens system 20 is moved.

Therefore, the microcomputer 34 is configured to monitor failures in one focusing information system and information that is weak in each, and automatically switch the adoption of focusing information, making it extremely easy to use and reliable. An imaging device capable of focusing can be provided.

For example, when focusing based on an infrared focusing information system, when photographing an underwater subject through a window or from above the water surface, the subject may not be in focus and the window itself or the water surface may be in focus. , in such a case, the microcomputer 34
It becomes difficult to automatically detect the situation of the subject within the camera.

Further, even when focusing is performed based on any focusing information, the microcomputer 34 may not be able to make a decision, or the photographer may wish to select a focusing information system based on his or her will.

Reference numerals 52 and 53 are selection switches for this purpose. For example, when photographing subject M in a dark place or a subject with low contrast, it can be determined that it is better to use infrared focusing information without relying on automatic detection. When the selection switch 52 is pressed, the microcomputer 34 stops using the video focusing information and switches to using the infrared focusing information, and also moves the front lens system 20 and the image sensor 24 to the in-focus position. The control signal is obtained by using the focal length X value and Y value as the distance that is not multiplied by 0.9 from the distance obtained by multiplying the focal length X value and Y value by 0.9, that is, the focusing distance X value and Y value as the moving distance of the front lens system 20 and the image sensor 24. is modified to generate .

Also, if you know that it is better to use video focusing information when photographing a subject such as through a window, if you press the selection switch 53, the microcomputer 31
In step 4, contrary to the above, the adoption of the focusing information of the infrared focusing information system is cut off, and the decoy image element 24 is controlled to be moved to the in-focus position by the information of the video focusing information system.

Accordingly, by operating these selection switches 52 and 53, the photographer can judge the situation of the subject, which cannot be achieved by automatic detection, so that more appropriate focusing can be performed.

In this embodiment, the front lens system 20 and the image sensor 24 are configured to move relative to each other, thereby making it possible to further implement telemacro photography.

Further, in this embodiment, direct distance measurement to the subject is performed using an infrared focusing method, but the method is not limited to this.
Any method that can perform direct distance measurement and has a high focusing speed may be used, such as an ultrasonic focusing method that includes an ultrasonic source and a light receiving section, or a so-called triangulation focusing method that includes a reflective mirror line sensor or the like.

Furthermore, although the front lens system 20 and the silver image element 24 are moved based on the two focusing information, the front lens system 20 is moved based on the two focusing information.
Alternatively, a configuration may be adopted in which only the silver image element 24 is moved.

In that case, power consumption can be reduced, although the focusing speed will be somewhat slower.

In addition, it is equipped with only a deofocusing information system,
Even if the front lens system 2o and the imaging cable 24 or the rear lens system 23 are moved at the same time, fast and accurate focusing can be achieved in the same way, and the focusing information system can be removed without having to do so. Because of this, it is possible to simplify and downsize the display, thereby reducing membership fees.

Furthermore, the front lens system 2o does not need to be driven by the motor 37, but may be driven manually by a known method.

Furthermore, in the above embodiment, the front lens system 2o and the silver image element 24 are moved relative to each other, but the rear lens system 23 may be moved instead of the image pickup element 24.

(Effects of the Invention) As described above, according to the apparatus according to claims (1) to (3), the front lens system and the rear lens system or the imaging element are provided so as to be movable with respect to each other. Telemacro photography becomes possible.

In particular, the device according to claim (1) is fast and can perform accurate focusing.

Further, in the device according to claim (2), since the focusing information can be selected depending on the shooting situation of the subject,
This enables focusing with good viscosity depending on the shooting situation.

Furthermore, the apparatus according to claim (3) has the advantage that the apparatus can be made smaller and the manufacturing cost 1 can be reduced.

[Brief explanation of the drawing]

FIG. 1 shows a schematic block system diagram of an embodiment of an imaging device according to the present invention. 20...Front lens system, 21...Zoom lens system,
22...Mirror, 23...Rear lens system, 24...
- Image sensor, 29... Infrared light source, 32... Light receiving lens, 34... Microcomputer, 36.47.
51...Drive circuit, 52.53...Selection switch. Patent applicant: Victor Japan Co., Ltd.

Claims (3)

[Claims] (1) On the optical axis, there is at least a front lens system, a variable magnification lens system for changing the magnification of the imaging light from the subject, a rear lens system for forming the imaging light into an image, and a lens system for converting the imaging light into an image. An imaging device comprising an image sensor that performs photoelectric conversion to extract a video signal using a photoelectric conversion surface, and a focusing information system that receives focusing information from the subject, comprising: the front lens system and the rear lens system; a first focusing information system that obtains the focusing information by direct distance measurement of the subject; and a second focusing information system that obtains the focusing information based on high-frequency components of the video signal. During focusing, based on the focusing information from the first and second focusing information systems, at least one of the front lens system, the rear lens system, or the image sensor is set to the optical axis. An imaging device characterized by having a configuration in which the top is moved. (2) The imaging apparatus according to claim (1), further comprising a switching means for selectively switching between the focusing information from the first focusing information system and the focusing information from the second focusing information system. . (3) On the optical axis, there is at least a front lens system, a variable magnification lens system for changing the magnification of the imaging light from the subject, a rear lens system for forming the imaging light into an image, and a rear lens system for converting the imaging light into an image. An imaging device comprising: an imaging device that performs photoelectric conversion on a photoelectric conversion surface to extract a video signal; and a focusing information system based on a high-frequency component of the video signal; elements are provided so as to be movable relative to each other on the optical axis, and during focusing, the front lens system, the rear lens system, or the imaging device are simultaneously moved on the optical axis based on the focusing information. An imaging device that uses