JP2762908B2 - Lens focus control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens focus control device applied to a television camera or the like, and more particularly to a lens focus control device for performing focusing at a variable speed according to the size of an iris aperture.

[0002]

2. Description of the Related Art A conventional lens focus control device includes a lens, an iris whose aperture is variable according to the brightness of a subject, and
An iris drive unit that performs drive to stop or open the aperture of the iris, and a focus drive unit that focuses an optical image of a subject formed on an imaging surface of an imaging element by moving a lens. I have. The lens focus control device moves a lens to an in-focus position in accordance with a distance to a subject, and focuses an optical image of the subject formed on an imaging surface.

When performing focusing, first, the aperture of the iris is reduced or opened by the iris drive unit in accordance with the brightness of the subject. Next, the lens is driven at a constant speed to a focus position corresponding to the focal length by the focus driving unit, and the optical image of the subject to be formed is focused.

[0004]

However, in general, when the aperture of the iris is opened, the depth of focus of the lens becomes small, so that it is difficult to focus. When the aperture of the iris is narrowed, the depth of focus of the lens becomes large. Focusing becomes easier. As described above, in the conventional apparatus, since the driving speed for driving the lens to the in-focus position is constant, when the iris is opened and it is difficult to focus, the driving speed is too high to make focusing difficult, and When the iris is narrowed down and focusing is easy, there is a problem that it takes too much time to focus because the driving speed is low.

SUMMARY OF THE INVENTION The present invention has been made to solve the problem that focusing cannot be performed reliably in an optimum time as described above, and an object of the present invention is to respond to a change in the depth of focus of a lens due to the position of an iris. It is an object of the present invention to provide a lens focus control device which controls a driving speed for driving a lens to a focus position by focusing, and can easily perform focusing in an optimum time.

[0006]

In order to achieve the above object, a lens focus control apparatus according to the present invention comprises a lens (1) for condensing light reflected from a subject, and a variable aperture according to the brightness of the subject. An iris (2) having an iris, an iris drive control means (3) for adjusting the aperture of the iris (2), and a focus drive control means (4) for driving and controlling the lens (1) to a focus position. It is configured to have. In this configuration, the iris drive control means (3) outputs a drive signal (Si) for driving the iris (2) based on the iris control switch (31) and a contact signal of the iris control switch (31). Iris drive signal generating means (32) and iris (2) according to the drive signal (Si)
Iris driving means (33) for driving the aperture diameter of the iris (2) in the opening direction or the aperture direction and outputting a driving state signal (Sj) indicating the driving state of the iris (2). The above-mentioned focus drive control means (4) outputs a drive state signal (Sj).
A focus drive speed control unit (44) for controlling the moving speed of the lens (1) to the in-focus position in accordance with the state of the aperture of the iris (2) based on the iris (2). It is characterized in that the moving speed of the lens (1) to the in-focus position is variable at a relatively low speed when it is on the side and at a relatively high speed when it is on the diaphragm side.

[0007]

Therefore, according to the lens focus control device of the present invention, the iris drive control means (3) opens the aperture of the iris (2) or drives in the direction of the aperture, and drives the iris (2). Drive state signal (Sj) indicating the state
Is output. The above-mentioned focus drive control means (4)
The drive state signal (S) output by the nest drive control means (3)
Based on j), the moving speed of the lens (1) to the in-focus position is controlled in accordance with the state of the aperture of the iris (2). With this control, the aperture speed of the iris (2) is relatively low when the aperture is on the open side, relatively high when the aperture is on the aperture side, and the moving speed of the lens (1) to the in-focus position is reduced. Be variable.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a lens focus control apparatus according to the present invention; FIG. 1 is a block diagram schematically showing an embodiment of a lens focus control device according to the present invention. As shown in FIG. 1, the apparatus includes a lens 1, an iris 2 having a variable aperture according to the brightness of the subject, an iris drive control unit 3 for driving the aperture of the iris 2 in the direction of aperture or opening, A focus drive control unit for driving the lens to a focusing position to focus an optical image of a subject formed on an imaging surface of an imaging device (not shown); The iris drive control means 3 further includes an iris control switch 31 and an iris control switch 3
An iris drive signal generator 32 that outputs a drive signal Si for driving the iris 2 based on the contact signal of the iris 2 and an iris drive unit 33 that opens the aperture of the iris 2 or drives the aperture in the aperture direction according to the drive signal Si. Become. Further, the iris driving unit 33 outputs a signal Sj indicating the driving state of the iris.

The focus drive control means 4 includes a focus control switch 41, a focus drive signal generator 42 for outputting a focus drive signal Sf1 for driving the lens based on a contact signal from the switch 41, an iris position detector 43, It comprises a focus drive speed control unit 44 and a lens drive unit 45. The iris position detector 43 outputs the signal S output from the iris driver 33.
In response to j, an aperture position signal Sd indicating the aperture position of the iris 2 is output. The focus drive speed control unit 44 receives the focus drive signal Sf1 and the aperture position signal Sd, and receives the control signal Sf
Outputs 2. The lens driving section 45 drives the lens 1 to the in-focus position based on the control signal Sf2.

In order to perform focusing, first, the iris drive control means 3 controls the iris 2 according to the brightness of the subject.
Aperture is throttled or opened. Specifically, when the iris control switch 31 is turned on, the iris drive signal generation section 32 outputs the iris drive signal Si. The output drive signal Si is input to the iris drive unit 33.
The iris driving unit 33 drives the aperture of the iris 2 and outputs a signal Sj indicating the driving state of the iris 2. The iris position detector 43 detects iris aperture position information based on the signal Sj, and outputs an aperture position signal Sd.

On the other hand, when the focal length of the lens 1 is determined according to the distance to the subject, the contact signal generated by the focus control switch 41 is input to the focus drive signal generator 42, and the focus drive signal generator 42 A focus drive signal Sf1 for driving the focus of the lens 1 to the in-focus position is output. Focus drive signal S
f1 is a signal for driving the lens 1 to the in-focus position according to the focal length.

The focus drive signal Sf 1 and the aperture position signal Sd output from the iris position detector 43 are input to a focus drive speed controller 44. The focus drive speed control unit 44
The input focus drive signal Sf1 is controlled based on the aperture position signal Sd, and a control signal Sf2 is output. That is, when the aperture of the iris 2 is on the open side, it is difficult to perform focusing, so that the driving speed for driving the lens 1 is reduced,
When the aperture of the iris 2 is on the aperture side, focusing can be easily performed. Therefore, control is performed based on the aperture position signal Sd so that the driving speed for driving the lens 1 is increased. The output control signal Sf2 is input to the lens driving unit 45,
The lens driving unit 45 controls the lens 1 based on the control signal Sf2.
Is driven to focus the subject image.

In this embodiment, the focus drive control means 4
Have an iris position detector 43 and a focus drive speed controller 44. Therefore, the driving speed of the lens 1 is controlled according to the aperture diameter of the iris 2, that is, the focal depth of the lens. When the aperture of the iris is on the open side, the driving speed of the lens 1 is slow, so that the focus control is easy. When the aperture of the iris 2 is on the aperture side, the driving speed of the lens 1 is fast, so that the focusing can be performed in an optimum time. There is an effect that can be done.

[0014]

According to the apparatus of the present invention, the focus drive control means detects the iris aperture position information, and the drive speed controls the lens driving speed based on the iris aperture position information. It comprises control means and lens driving means. Therefore, the driving speed of the lens can be controlled according to the iris aperture position, that is, the focal depth of the lens, and there is an effect that focusing can be performed in an optimum time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a lens focus control device according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lens 2 iris 3 iris drive control means 4 focus drive control means 43 iris position detection section 44 focus drive speed control section 45 lens drive section Si iris drive signal Sj signal indicating iris drive state Sd aperture position signal Sf1 focus drive signal Sf2 control signal

Claims (2)

(57) [Claims] 1. A lens (1) for condensing reflected light from a subject, an iris (2) having a variable aperture according to the brightness of the subject, and an aperture of the iris (2) adjusted. A lens focus control device comprising: an iris drive control means (3) for controlling the lens (1) to a focus position; and a focus drive control means (4) for driving and controlling the lens (1) to a focus position. 3) an iris control switch (31) and an iris drive signal generating means (32) for outputting a drive signal (Si) for driving the iris (2) based on a contact signal of the iris control switch (31).
And the iris (2) according to the drive signal (Si).
An iris driving means (33) for driving the aperture diameter of the iris (2) in the opening direction or the iris direction and outputting a driving state signal (Sj) indicating a driving state of the iris (2). ) Is the driving state signal (S
j) a focusing drive speed controller (44) for controlling a moving speed of the lens (1) to a focus position according to a state of a stop of the iris (2); The moving speed of the lens (1) to the in-focus position is variable at a relatively low speed when the aperture is on the open side and at a relatively high speed when on the aperture side. Lens focus control device. 2. The iris position detection unit further outputs an aperture position signal (Sd) indicating an aperture position of the iris (2) based on the drive state signal (Sj). (43) and the lens (1)
A lens driving unit (45) for driving the lens (1) to a focus position, wherein the focus driving speed control unit (44) moves the lens (1) according to the state of the diaphragm based on the diaphragm position signal (Sd). The lens focus control device according to claim 1, wherein a speed control signal (Sf2) is output, and the lens driving unit (45) drives the lens (1) based on the control signal (Sf2).