JPH07177527A - Auto focus adjustment device for multi-ccd electronic camera - Google Patents

Abstract

PURPOSE:To provide the auto focus adjustment device for the multi-CCD video camera using a conventional conversion lens without modification whose size is made small and whose weight is made light. CONSTITUTION:An image pickup means in which color image pickup elements 5R, 5G, 5B are fixed to a color separation prism 6 is mounted to an image pickup section mount 7 moving in the direction of an optical axis. A detection circuit 10 detects a high frequency component required for focusing from a signal via a video process circuit 9 (contrast detection method). A position sensor 11 detects and absolute position of the image pickup section mount 7, a CPU 13 implements hill-climbing AF processing arithmetic operation based on detection data from the detection circuit 10 and position data from a position sensor 11 to control a motor driver 12. The CPU 13 discriminates a drive direction in which the detected data are increased, and while the image pickup section mount 7 is driven in a direction where the detected data is further increasing, the image pickup section mount 7 is moved to a position when the detected data are maximized to perform auto focus operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus adjusting device for an electronic camera, and more particularly to an autofocus adjusting device for a multi-plate electronic camera.

[0002]

2. Description of the Related Art Conventional multi-plate electronic cameras for business use have abundant interchangeable lenses, but these interchangeable lenses cannot be autofocused. Further, in the case of a conventional autofocus mechanism (hereinafter referred to as an AF mechanism) for focusing on the lens side, a lens driving device is installed in the lens barrel, and there is a space between the camera body and the lens unit. Since a signal line and a line for supplying electric power must be installed, there are problems that the device becomes complicated, the lens becomes large, and the weight increases.

Further, in an AF mechanism for driving a lens, which moves the front lens, the front lens has a considerable weight and has a large driving stroke, so that a certain driving force is required to move the front lens. However, there are problems such as further enlargement of the lens, increase in weight, difficulty in speeding up AF, and the like.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, the present invention uses a wide variety of interchangeable lenses that have been used so far to enable autofocusing, thereby reducing the size and weight of a multi-plate electronic camera. The point is to provide an adjusting device.

[0005]

SUMMARY OF THE INVENTION The present invention is an autofocus adjusting apparatus for a multi-plate electronic camera, which comprises an image pickup lens and an image pickup means in which an RGB image pickup element is fixed to a color separation prism. And a drive unit for moving the image pickup unit along the optical axis based on a focus detection result by the focus detection unit. The image pickup unit is a two-plate CCD or a three-plate CCD image pickup unit. To be done.

[0006]

FIG. 1 is a block diagram of a video camera equipped with an autofocus adjusting device of the present invention. This embodiment shows an example in which the focus adjusting device of the present invention is applied to a video camera equipped with RGB three-plate CCD image pickup means. ing. Figure 1
In FIG. 1, reference numeral 1 denotes a video camera main body, a photographing lens device 3 is attached to a lens mount portion 2 of the video camera main body 1, and the photographing lens device 3 includes a plurality of lens groups 4. The taking lens device 3 may be replaceable or fixed.

Reference numerals 5R, 5G, and 5B are RGB solid-state image pickup devices each composed of a CCD and a color filter, and are fixed to predetermined positions of the color separation prism 6.
In this embodiment, the three-plate type is used, but the number of solid-state image pickup elements and the configuration of the prism may be changed, and the two-plate type may be used. The color separation prism 6 is accurately fixed to an image pickup mount 7 that is movable in the optical axis direction. Then, the imaging unit mount 7 is driven by a driving device 8 such as a motor.

The light incident from the image pickup lens 3 is converted into an electric signal by the solid-state image pickup devices 5R to 5B, and a predetermined electric processing is performed by the video process circuit 9. In this embodiment, since the contrast detection method (frequency separation method) is adopted as the autofocus method, the information that the image when the image is in focus has a large contrast ratio, that is, the frequency component is high is used for focusing. is doing. Therefore, a detection circuit 10 is provided, and the detection circuit 10 detects a high frequency component necessary for focusing from the signal passed through the video process circuit 9. Hereinafter, this detection output will be described as an evaluation value.

Further, 11 is a position sensor, and the position sensor 1
Reference numeral 1 detects the absolute position of the image pickup mount 7. 12
Is a motor driver, and the motor driver 12 is the CPU 1
The drive device 8 is driven by the control signal from the controller 3. The CPU 13 performs a hill-climbing AF process calculation based on the detection data (evaluation value) from the detection circuit 10 and the position data from the position sensor 12, and controls the motor driver 12.

A display device (viewfinder) 14 displays the video signal processed by the video process circuit 9.
Therefore, it is possible to confirm the imaging. 1
A recording device 5 includes a recording medium for recording the video signal processed by the video process circuit 9. The recording medium may be a magnetic tape, an IC card, a hard disk, a magneto-optical disk, a floppy disk, or the like, and a video signal may be output to the outside of the camera and recorded by an external recording device.

The automatic focusing operation of the embodiment employing the contrast detection method will be described below. In FIG. 1, when the autofocus mechanism is activated, the CPU
Reference numeral 13 controls the motor driver 12 so as to move the image pickup unit mount 7 back and forth in a predetermined pattern, determines a drive direction in which the evaluation value increases, and drives in that direction. Then, while driving the image pickup unit mount 7 in the direction in which the evaluation value further increases, the position where the evaluation value becomes maximum is always stored.

When the difference between the present value and the maximum value of the evaluation values becomes larger than a predetermined value, the image pickup mount 7 is driven to the position where the evaluation value becomes the maximum, and the series of autofocus operation is completed.

It is also possible to perform manual focusing by releasing the autofocus operation, providing an input device for the focus adjustment direction, and reading it by the CPU 13 to control the motor driver 12. Further, in the above-described embodiments, the present invention has been described by way of an example in which the autofocus operation is performed by the contrast detection method, but the invention is not limited to the contrast detection method, and it is also possible to adopt, for example, an image sensor system, an infrared system or the like. .

[0014]

According to the present invention, in the multi-plate type image pickup device, the image pickup element integrated with the color separation prism is moved without moving the lens for focusing. Therefore, the existing interchangeable lens group is modified. It becomes possible to use auto focus without using it. Further, since the amount of movement for focusing can be reduced and the space for installing the drive device for focus adjustment has a margin, it is easy to obtain a high output from the drive device, and the autofocus can be speeded up. Further, since it is not necessary to install a motor or sensors inside the lens, the size and weight of the taking lens can be reduced, and it is not necessary to connect a power source or a signal line from the camera body to the lens side.

[Brief description of drawings]

FIG. 1 is a block diagram of a multi-plate electronic camera autofocus adjustment device of the present invention.

[Explanation of symbols]

 4 Imaging Lens Group 5R, 5G, 5B Color Imaging Element 6 Color Separation Prism 7 Imaging Mount 8 Drive Motor 9 Video Process Circuit 10 Detection Circuit 11 Position Sensor 12 Motor Driver 13 CPU 15 Recording Device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H04N 5/232 A

Claims (2)

[Claims] 1. An autofocus adjusting device for a multi-plate electronic camera comprising an image pickup lens and an image pickup means having an image pickup element fixed to a color separation prism, wherein the focus detection device and the focus detection result by the focus detection device An autofocus adjusting device for a multi-plate electronic camera, comprising: a driving unit that moves an imaging unit along an optical axis. 2. The autofocus adjusting device for a multi-plate electronic camera according to claim 1, wherein the image pickup unit is a two-plate type or a three-plate type image pickup unit.