JPH05336428A - Video camera - Google Patents

Abstract

PURPOSE:To securely put a lens back to the position where the lens is positioned just before the power source is turned OFF even if the lens moves after the power source is turned OFF by omitting a process wherein a control means is manually made to memorize physical information characteristic to the lens unit after the lens unit is combined with a main camera body. CONSTITUTION:This video camera is equipped with the control means 12 which controls the motion of the lens unit 1 even when the lens unit 1 and main camera body 2 are combined together by using the characteristic physical information on the lens unit stored in a nonvolatile storage means 8 in the lens unit 1 for imaging a subject on an image formation surface. Further, this video camera is equipped with a nonvolatile storage means 8 which stores and holds the position of the lens at the time of power-OFF operation and a means which moves the lens to its reference position at the time of the power-ON operation and then moves the lens to the lens position stored in the nonvolatile storage means 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera, and more particularly to a video camera having an autofocus device.

[0002]

2. Description of the Related Art Focusing when shooting with a video camera is called focus adjustment. In recent years, a video camera having an autofocus device for automatically performing focus adjustment has been provided.

The autofocus mechanism automatically controls the movement of the lens for focusing by an electric signal obtained by distance measurement or focus detection using electric means. As a focus detection method adopted, for example, there is a so-called hill-climbing method in which the focusing lens is moved to a position where the high frequency component of the video signal from the image sensor is maximized.

By the way, the lens unit of the video camera includes a plurality of optical lenses which are roughly classified into a front lens group and a rear lens group. The rear lens group is located between the front lens group and the image plane. Focus adjustment is generally divided into a method of driving the front lens group and a method of driving the rear lens group. However, in the method of driving the front lens group, the structure for driving the lens becomes large, so that the driving structure is relatively simple, and the method of driving the rear lens group that consumes less power is often adopted. There is. The rear lens group is provided with a pulse motor for driving and a reference position detecting means. The reference position is provided so that the value of the counter that adds or subtracts the number of pulses supplied to the pulse motor depending on the rotation direction of the motor and the position of the rear lens group correspond exactly to each other. It is a thing. When the reference position detecting means detects that the rear lens group is at the reference position, the counter is reset to a value corresponding to the reference position. Also, the pulse motor is controlled according to the magnitude of the high frequency component of the video signal,
It is driven at a rotation angle and a rotation speed proportional to the number of given pulses or the pulse repetition rate.

The above is the outline of the autofocus device in the video camera. When assembling the video camera,
Physical information unique to the lens unit necessary for controlling the movement of the lens unit, for example, position information at the wide end and the tele end of the zoom lens should be measured in the state of the lens unit alone. This is because the entire object to be measured becomes large after assembly and may damage the camera body, which is not directly related to measurement. Therefore, after measuring the physical information, the lens unit and the camera body are combined, and the measured physical information is manually stored in the control means provided in the camera body.

The positions of the wide end and the tele end of the zoom lens are, as shown in FIG. 3, when the subject is at infinity and the rear lens group is on the infinity side. The two positions are at the in-focus positions, that is, at the two points where the zoom tracking curve when the subject is at infinity and the horizontal axis that shows the rear lens group is at infinity. These positions vary from lens unit to lens unit due to a mounting error of a zoom encoder such as a variable resistor mounted to detect the position of the zoom lens. Also,
Other physical information unique to the lens unit includes variations in the zoom tracking curve. This is due to the accuracy of the cam mechanism for moving the lens in the optical axis direction. By measuring whether the position of the rear lens group is off from the standard zoom tracking curve, the zoom tracking Used as correction data.

On the other hand, when operating the completed video camera, when the power of the video camera is turned on, the rear lens group is unconditionally controlled so as to return from the power-off position to the reference position. This is for resetting the counter that counts the number of pulses applied to the pulse motor at the reference position, so that the value of the counter and the position of the rear lens group may correspond exactly one-to-one. However, the shooting operation is forced to be interrupted at the time of shooting, the power of the video camera is turned off, and the rear lens group is returned to the reference position despite the desire to continue the previous shooting operation when the power is turned on immediately after. Therefore, it was necessary to perform the same focus adjustment as before the power was turned off again. Therefore, JP-A-3-119872 (H04N
5/232), in order to solve this problem, after the power is turned on, the movement amount when the rear lens group moves to the reference position is detected, and after the movement to the reference position, the detected movement amount is It has been proposed to return it to its original position.

[0008]

However, in the conventional video camera, after assembling the lens unit with the camera body at the time of assembling, the physical information unique to the lens unit is manually stored in the control means separately provided in the camera body. I have to let it go.

Further, in the conventional method for solving the problem caused by the rear lens group returning to the reference position when the power is turned on when operating the completed video camera, the shock and vibration applied to the video camera after the power is turned off. Therefore, if the rear lens group has moved, it cannot be returned to the position immediately before the power was turned off.

[0010]

In order to solve the above two problems, the present invention uses a non-volatile memory means.

That is, a lens unit for forming an image of a subject on an image forming surface, and a non-volatile storage means provided in the lens unit and storing physical information specific to the lens unit measured by the lens unit alone. Controlling means for controlling the movement of the lens unit using information from the non-volatile storage means in a state where the lens unit and the camera body are combined.

A video camera for automatically focusing by moving a lens unit for forming an image of an object on an image forming surface, which stores the position of the lens when the power is cut off, Also stores non-volatile storage means, first moving means for moving the lens to a reference position when the power is turned on, and after the movement by the first moving means is completed, the lens is stored in the non-volatile storage means. Second moving means for moving the lens to the position stored in the lens.

[0013]

The physical information peculiar to the lens unit stored in the non-volatile storage means is inputted to the control means for automatically controlling the movement of the lens unit.

Further, the position information of the lens when the power is turned off, which is stored in the non-volatile storage means, is not affected even if the position of the lens changes after the power is turned off.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a functional block diagram showing a video camera which is an embodiment of the present invention. In the figure, 1 is a lens unit, and 2 is a camera body. Lens unit 1
Includes a front lens 3a and a zoom lens 3b, which form a front lens group, and a rear lens group 4. Then, the zoom lens 3b is moved back and forth to change the magnification, and the pulse motor 5 is used to move the rear lens group 4 back and forth to correct the focusing operation and the deviation of the image plane due to the back and forth operation of the zoom lens 3b. Based on the zoom tracking curve. Further, 6 is a zoom encoder for detecting the position of the zoom lens 3b, and 7 is a reference position detecting means for detecting that the rear lens group 4 has reached the reference position. The reference position can be set at any position within the movable range of the rear lens group 4, and is set to the midpoint of the movable range in this embodiment.

Reference numeral 8 denotes a non-volatile storage means composed of an EEPROM or the like, which is physical information specific to the lens unit measured before the lens unit 1 is combined with the camera body 2, for example, the wide end of the zoom lens 3b or the telephoto. Edge position information is stored in advance.

On the other hand, the front lens 3 is attached to the camera body 2.
a, a zoom lens 3b, and an image pickup device 9 such as a CCD for converting light from a subject passing through the rear lens group 4 into an electric signal, and the electric signal from the image pickup device 9 is imaged by a video signal processing circuit 10. The signal is processed and output. Further, the video signal is input to the microcomputer 12 through the high pass filter 11. The microcomputer 12 controls the pulse motor 5 by so-called hill climbing control to move the rear lens group 4 so that the input high frequency image signal component becomes maximum. Further, in the state where the lens unit 1 and the camera body 2 are combined, each information from the zoom encoder 6, the reference position detecting means 7, and the non-volatile storage means 8 is also input to the microcomputer 12. Therefore, the physical information peculiar to the lens unit measured before the lens unit 1 is combined with the camera body 2 is a microcomputer 12 which is a control means separately provided in the camera body 2 after the lens unit 1 and the camera body 2 are combined. No need to type in.

In the microcomputer 12,
As a means for detecting the position of the rear lens group 4, a counter 13 for adding or subtracting the number of pulses applied to the pulse motor 5 according to the rotation direction of the pulse motor 5 is provided. Also, 14 is a power switch.

Next, the operation of the video camera shown in FIG. 1 when the power is turned on and off will be described with reference to the flow chart shown in FIG.

First, the case where the power is turned off after the video camera finishes shooting will be described. When the power switch 14 is turned off (S1), the power is not turned off immediately, but the position of the rear lens group 4, that is, the counter 1
The value of 3 is stored in the non-volatile storage means 8 (S2), and the set value of the automatic white balance adjustment in the video signal processing circuit 10, that is, the amplification factor of the color signal amplification circuit is also stored in the non-volatile storage means 8 (S3). ), The power is turned off (S4), and the power off routine is terminated (S5).

On the other hand, when the power is turned on, the power switch 1
When 4 is turned on (S11), the power is immediately turned on (S12). Then, it is judged from the information from the reference position detecting means 7 whether the rear lens group 4 is at the reference position or not (S13). If the rear lens group 4 is not at the reference position, the rear lens group 4 is moved (S14) to set the reference position. Then, it is stopped (S15), and the value of the counter 13 is set to a value corresponding to the reference position (S16). Next, it is judged whether or not the rear lens group 4 is stored at the position of the rear lens group 4 stored in the non-volatile storage means 8 immediately before the power is turned off (S17). The group 4 is moved (S18), stopped at this position (S19), and the power-on routine is ended (S18).
20). Therefore, even if the rear lens group 4 is returned to the reference position, the rear lens group 4 automatically returns to the position when the power is cut off. Moreover, the rear lens group 4 stored in the non-volatile storage means 8 when the power is cut off
The position information of is not affected even if the position of the rear lens group 4 changes even after the power is turned off, so that the position information can be surely restored.

Although the embodiments of the present invention have been described above, the non-volatile storage means for storing the positional information of the rear lens group 4 is provided separately from the non-volatile storage means 8 for storing the physical information specific to the lens unit. It goes without saying that it may be provided in the camera body 2.

[0024]

According to the present invention, by providing the non-volatile storage means, the physical information unique to the lens unit stored in the storage means is inputted to the control means for automatically controlling the movement of the lens unit. After combining the lens unit and the camera body, it is not necessary to manually input to the camera body 2 separately.

Further, the position information of the lens when the power is cut off, which is stored in the non-volatile storage means, is not affected even if the position of the lens changes after the power is cut off. Can be returned to.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment of the present invention shown in FIG.

FIG. 3 is a graph showing a zoom tracking curve of a lens unit.

[Explanation of symbols]

 1 lens unit 2 camera body 4 rear lens group 5 pulse motor 7 reference position detection means 8 non-volatile storage means 12 microcomputer 13 counter

Claims (2)

[Claims] 1. A lens unit for forming an image of an object on an image forming surface, and a non-volatile storage means provided in the lens unit and storing physical information specific to the lens unit measured by the lens unit alone. A video camera, comprising: a control unit that controls the movement of the lens unit using information from the non-volatile storage unit in a state where the lens unit and the camera body are combined. 2. A video camera for automatically focusing by moving a lens for forming an image of an object on an image forming surface, the position of the lens being stored when the power is cut off, and the power being cut off even after the power is cut off. A non-volatile storage means for holding stored contents; a first moving means for moving the lens to a reference position when the power is turned on; and a lens for storing the non-volatile storage means after the movement by the first moving means is completed. A second moving means for moving the lens to the stored position of the lens, the video camera.