JP3368062B2 - Lens system - 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 system having a zoom lens and a zoom lens operating member used in, for example, a television camera.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram of a conventional example, and is a block diagram of a lens system provided in a television camera or the like for adjusting a focal length. Inside Zoom Demand 1,
A potentiometer 2 is provided, and the potentiometer 2 is composed of a resistance R and a slider W movable on the resistance R. Both ends of the resistor R have a fixed voltage source 4 of an output voltage value + V, -V inside the zoom lens 3,
5, the slider W is sequentially connected to the + terminal of the subtractor 6 provided in the zoom lens 3, the operational amplifier 7, and the motor 9 that drives the lens 8 having the zoom function, and the slider W of the subtractor 6 is connected. The output of the speed detector 10 for detecting the angular speed of the motor 9 is fed back to the-terminal.

When the operator operates the zoom demand 1 in order to adjust the focal length, the slider W of the potentiometer 2 moves in accordance with the operation amount and direction, and the contact point with the resistance R moves and slides. The output power from the child W changes. Such a change in the output from the slider W is input to the subtractor 6 as a speed command signal. On the other hand, the speed detector 10 detects the rotation speed of the motor 9 and outputs it to the subtractor 6 as an angular speed signal. The subtractor 6 calculates the difference between the speed command signal and the angular velocity signal, and outputs the calculation result to the operational amplifier 7 as a difference signal. The operational amplifier 7 amplifies this difference signal amount and then supplies it to the motor 9, drives the motor 9 and moves the lens 8 to a position corresponding to the operation of the zoom demand 1.

In this conventional example, the lens control is so-called speed control, and the relationship between the operation amount of the zoom demand 1 and the moving speed of the lens 8 is uniquely determined. However, when zooming from the telephoto end to the close-up end is performed with the operation amount of the zoom demand 1 kept constant, the change in the angle of view does not become constant, and the change in the angle of view near the telephoto end. It gives the impression of being faster. In addition, it is very difficult to operate the zoom demand 1 so that the change in the image field is constant.

In recent years, in order to solve the above-mentioned drawbacks, a lens system has been devised which controls the lens so that the change in the angle of view and the operation amount of the zoom demand 1 are constant, and FIG. It is a block diagram of the other conventional example of a lens system. Inside the zoom demand 11, there is provided a potentiometer 12 composed of a resistor R and a slider W, and both ends of the resistor R have a fixed voltage source 14 whose output value inside the zoom lens 13 is + V, -V. 15 is connected, and the output of the slider W is transmitted via an A / D converter 16 to an arithmetic unit 17, such as a microcomputer, a D / A converter 18, a subtractor 19
Is connected to the + terminal of the subtractor 21 via the operational amplifier 20, and the output of the subtractor 21 is sequentially connected to the operational amplifier 22 and the motor 24 that moves the lens 23.
The output of the position detector 25 that detects the position of the lens 23 is fed back to the-terminal of the subtractor 19, and the output of the speed detector 26 that detects the angular velocity of the motor 24 is fed back to the-terminal of the subtractor 21. .

When the operator operates the zoom demand 11 in order to adjust the focal length, the resistance R moves up and down in the potentiometer 12 in conjunction with the operation amount and direction of the potentiometer 12 to move the slider W. The contact moves. Slider W
The output power from is uniquely associated with the position of this contact. The output from the slider W is converted into a digital signal by the A / D converter 16 at regular sampling times, and then input to the arithmetic unit 17 at regular sampling times. The computing device 17 computes a lens position command value that represents the position to which the lens 23 is moved. The lens position command value obtained here is converted again into an analog signal by the D / A converter 18 every sampling time, and the subtracter 19
Entered in.

During this period, the position detector 25 detects the position of the lens 23 and outputs it as a lens position signal to the subtractor 19. In the subtractor 19, the output signal from the D / A converter 18 and this The difference from the lens position signal is obtained and is input to the operational amplifier 20 as a difference signal. The velocity detector 26 detects the angular velocity of the motor 24 and outputs it as an angular velocity signal to the subtractor 21, and the input signal is amplified by the operational amplifier 20 and output to the subtractor 21. The subtractor 21 calculates the difference between the output signal from the operational amplifier 21 and this angular velocity signal, and outputs the difference to the operational amplifier 22 as a difference signal. The operational amplifier 22 amplifies this difference signal and outputs it to the motor 24. Motor 2
4 moves the lens 23 to a position corresponding to the operation of the zoom demand 11 based on this signal.

In this conventional example, the lens control is so-called position control in which the lens 23 is moved based on the change in the position of the lens 23 before and after the movement. It is possible to control the lens 24 such that the field changes are constant.

[0009]

However, in the conventional example as shown in FIG. 7, since the lens control is so-called position control, the difference between the position where the lens 23 should be moved and the position before the movement of the lens 23 is different. The lens 23 cannot be moved unless it becomes large to some extent. Especially, when performing very slow zooming called slow zoom, the lens 23
Does not move smoothly, and such a movement of the lens 23 is reflected in the image.

An object of the present invention is to solve the above-mentioned problems and to make the change of the angle of view constant with respect to the manipulated variable of the zoom demand.
Another object of the present invention is to provide a lens system that allows the lens to move smoothly even during slow zoom.

[0011]

A lens system according to a first invention for achieving the above object is a lens system comprising a zoom lens for a television camera and a zoom operating member for operating the zoom lens. Lens position detecting means for detecting the position of the lens having a zoom function,
Driving means for driving the lens, subtracting means for obtaining a difference signal between the lens command value signal output from the zoom operation member and the lens position signal output from the lens position detecting means, and an offset from the lens position signal A calculation means for calculating a value and an amplification means for amplifying an output signal of the calculation means are provided, and a signal obtained by adding the offset value to a difference signal between the lens command value signal and the lens position signal is used. It is characterized in that the lens is controlled.

The lens system according to the second invention is
In a lens system provided with a zoom lens for a television camera and a zoom operating member for operating the zoom lens, first computing means for computing a lens position command value signal based on an operation amount of the zoom operating member, Lens position detecting means for detecting the position of the lens having a zoom function,
Speed detecting means for detecting the moving speed of the lens, driving means for driving the lens, and a differential signal between the lens position command value signal and the lens position signal output from the lens position detecting means. 1 subtraction means,
Second computing means for computing the offset value from the lens position signal, third computing means for computing using the signal and offset value obtained from the first subtracting means, and And a second subtracting means for obtaining a difference signal between the output signal from the first amplifying means and the output signal from the lens speed detecting means. And a second amplifying means for amplifying the signal obtained by the second subtracting means, and a signal obtained by adding an offset value to a difference signal between the lens position command value signal and the lens position signal. Is used to control the lens.

[0013]

In the first and second lens systems having the above-described structure, the calculating means calculates the lens position command value indicating the moving position of the zoom lens from the operation amount of the zoom operating member, and the lens position detecting means calculates the lens position. A lens position signal indicating the position of is output. In the subtraction means, a difference signal between the lens position command value and the lens position signal is obtained, and an offset value is calculated based on this signal and the lens position signal,
A signal is obtained by adding an offset value to the output signal of the subtraction means. Then, in the first invention, lens control is performed using this signal, and in the second invention, the lens is controlled based on this signal and the output signal from the lens speed detecting means.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a block diagram of the first embodiment. Inside the zoom demand 31, a resistor R and a slider W are provided.
A potentiometer 32 constituted by is provided, and both ends of the resistor R have a voltage value + V inside the zoom lens 33,
-V fixed voltage sources 34 and 35 are connected via a signal line, and the output of the slider W is the A / D inside the zoom lens 33.
A converter 36, a computing device 37 such as a microcomputer,
D / A converter 38, + terminal of subtractor 39, operational amplifier 4
0, the motor 42 for driving the lens 41 having the zooming function is sequentially connected. Further, the output of the position detector 43 for detecting the position of the lens 41 is the A / D converter 36.
The output of a speed detector 44 for sequentially detecting the angular speed of the motor 42 is fed back to the minus terminal of the subtractor 39.

When the operator operates the zoom zoom demand 31 in order to adjust the focal length, the potentiometer 3
In 2, the slider W moves along the resistance R in conjunction with the operation amount and direction, and the contact point with the resistance R moves. The position of this contact point and the output power from the slider W uniquely correspond to each other, and the output from the slider W is converted into a digital signal by the A / D converter 43 to obtain a demand signal S _n for a certain sampling time. It is input to the arithmetic unit 37 every time. Also,
The position detector 43 detects the position of the lens 41, and this detection signal is converted into a digital signal representing a certain numerical value by the A / D converter 43, and the arithmetic device 37 is provided as the lens position signal P _{n at} every predetermined sampling time. Has been entered in. The arithmetic unit 37 uses the demand signal S _n and the lens position signal P _n.
And are processed to generate a control signal for the motor 42.

FIG. 2 is a flow chart showing the process of the arithmetic processing of the arithmetic unit 37. In step S1, the demand signal S _n is taken in from the A / D converter 32 at every predetermined sampling time, and in step S2 this demand is taken. The signal S _n is normalized to create a normalized signal S ^* _n . As expressed by the following equation,
Normal signal S ^* _n is obtained by dividing the demand signal S _n at the maximum value Smax of the total demand signal S _n. S ^* _n = S ^* _n / Smax (1)

In step S3, a focal length command value representing a desired focal length is calculated based on the normalized signal S ^* _n . Incidentally, the operation amount of the zoom demand 31, in order to make constant the variation of the angle of view, the focal distance command value F _n, 1 before sampling the focal length instruction value F _n-1 at the current sampling time It is necessary to keep the ratio, that is, _Fn / _Fn-1 = c constant. This is possible by using the following equation. _{F n = F n-1 ·} (Ft / Fw) a [ _{^{However, a = S * n · c}} ] ... (2)

Here, Fw is the focal length at the wide-angle end, and Ft
Is the focal length at the telephoto end, and the constant c is the reciprocal of the time T required to move the lens 41 at the maximum speed from the wide-angle end to the telephoto end divided by the sampling time δt, that is, c = δt / T.

In step S4, the lens position command value C _n is calculated from the focal length command value F _n using a preset conversion table or calculation formula, and is stored together with the lens position command value C _n before sampling.

In step S5, the arithmetic unit 37 fetches the lens position signal P _n obtained by the position detector 43,
S6 subtracts the lens position signal P _n from the lens position command value C _n as shown in the following equation to generate a difference signal P ^* _n in. P ^* _n = C _{n −} P _n … (3)

In step S7, the offset value Poff is calculated by a predetermined function f (P _n ) using the lens position signal P _n as a variable. For example, a function as shown in FIG. 3 can be used, the vertical axis represents the offset value Poff, and the horizontal axis represents the lens position signal value P _n . This function Poff = f (P _n ) is mathematically expressed as the following equation. Poff = Ow [Pw ≤ P _n ≤ Pa] (4) Poff = (Ob-Ow) / (Pb -Pa) ・ (P _n -Pa) + Ow [Pw ≤ P _n ≤ Pa] (5) Poff = (Ot-Ob) / (Pt -Pb) · (P n -Pb) + Ob [Pb ≦ P n ≦ Pt] ... (6)

The constant Pw is the lens position signal P _n when the lens 41 is at the wide-angle end, and the constant Pt is the lens position signal P _n when the lens 41 is at the telephoto end.

[0023] In step S8, taking into account the sign of the difference signal P ^* _n, adds the offset value Poff obtained in step S7 the difference signal P ^* _n calculated in step S6 or subtracted to the signal P ^** Calculate n. The lens position command value C _n at the current sampling point and the lens position command value one sampling before are C
_From the relationship with _n-1 , the signal P ^** _n can be obtained from the following equation. _{^{P ** n = P * n +}} Poff [C n -C n-1 <0] ... (7) P ** n = P * n -Poff [C n -C n-1> 0] ... (8) P _{^{** n = P * n +0 (}} Poff = 0) [C n -C n-1 = 0] ... (9)

In step S9, the signal P
^{** The} lens speed command value V _n is obtained by multiplying _n by a certain gain G.
To calculate. V _n = G · P ^** _n (10)

In step S10, this lens speed command value V _n
Is output to the D / A converter 44 and converted into an analog signal. Further, this analog signal is output to the subtractor 39, and the difference from the angular velocity signal obtained by the velocity detector 44 is calculated. This differential signal is amplified by the operational amplifier 43 and then input to the motor 42 to drive the motor 42 and move the lens 41 to a position corresponding to the operation of the zoom / zoom demand 31.

In the present embodiment, as shown in FIG.
The angle of view can be changed at a constant rate while the operation amount of 1 is held constant, and the lens 41 can be moved smoothly even when a slow zoom is performed.

FIG. 4 is a block diagram of the second embodiment. A potentiometer 52 having a resistor R and a slider W is provided in a zoom demand 51, and a zoom lens 53 is provided at both ends of the resistor R. The fixed voltage sources 54 and 55 having the output voltage values + V and -V inside is connected via a signal line, and the output of the slider W is an A / D converter 56 inside the zoom lens 54, a microcomputer, etc. Arithmetic unit 57, D / A converter 5
8, an operational amplifier 59, and a motor 61 for moving a lens 60 having a zoom function are sequentially connected. Further, the output of a position detector 62 such as an incremental encoder that detects the position of the lens 60 is sequentially connected to a computing device 57 via a counter 63.

When the operator operates the zoom demand 51, the slider W moves along the resistance R in the potentiometer 52 in conjunction with the operation amount, and the contact point with the resistance R moves. The output voltage value of the slider W uniquely corresponds to the position of this contact, the output of the slider W is converted into a digital signal by the A / D converter 56, and is determined by the arithmetic unit 56 as a demand signal S _n. Input every sampling time of.

During this time, the position detector 62 detects the position of the lens 60 and outputs it to the counter 63 as a digital amount. The counter 63 accumulates this digital amount at any time, stores it as a lens position signal P _n , and outputs it to the arithmetic unit 57 at every predetermined sampling.

In the arithmetic unit 57, these demant signal S _n and lens position signal P _n are arithmetically processed, and the motor 61
Are creating control signals for. This calculation process is shown in FIG.
The lens velocity command value V _n shown in the equation (10) is obtained, and the lens velocity U _n representing the velocity of the lens 60 at the current sampling time is obtained, which is substantially the same as the flowchart shown in FIG.
The lens speed U _n is displayed as the following equation using the lens position signal P _n stored in the counter 63, the lens position signal P _n-1 input one sampling before, and the sampling time δt. U _n = (P _n −P _n-1 ) / δt… (11)

Then, the arithmetic unit 57 determines the lens speed command value.
Subtract V _n and lens velocity U _n . This result is output to the D / A converter 58 as a differential signal, converted into an analog signal, amplified by the operational amplifier 59, and then transferred to the motor 61.
Is supplied to. As a result, the motor 61 is driven, and the zoom demand 31 is adjusted by the calculated speed of the lens 60.
Move to the position corresponding to the operation of.

In the first embodiment, the moving speed of the lens 41 is detected by an analog amount by detecting the angular speed of the motor 42, but in the second embodiment, the position detector 6 is used.
In 2, the position before the movement of the lens 60 is detected as a digital amount, and the moving speed of the lens 60 is calculated, whereby the same effect as that of the first embodiment can be obtained.

When obtaining the signal P ^** _n , the equations (7) to
Instead of using (9), the following expression can be used. _{^{P ** n = P * n +0}} (Poff = 0) [C n -C n-1> 0, P * n ≦ 0] ... (12) P ** n = P * n + Poff [C n -C n _{^{-1> 0, P * n>}} 0] ... (13) P ** n = P * n +0 (Poff = 0) [C n -C n-1 = 0] ... (14)

FIG. 5 is a block diagram of the third embodiment. An encoder 72 is provided inside the zoom demand 71, and the output of the encoder 72 is a counter 73 and an arithmetic unit 7.
4 are sequentially connected to each other, and the output of the arithmetic unit 74 is further connected to the arithmetic units 76,
The D / D converter 77, the operational amplifier 78, and the motor 80 that drives the lens 79 having a zoom function are sequentially connected. Further, the output of a position detector 81 such as an incremental encoder for detecting the position of the lens 79 is output by a counter 82.
It is connected to the arithmetic unit 76 via.

When the operator operates the zoom demand 71, a pulse train is output from the encoder 72 according to the operation. This pulse train is added or subtracted in the counter 73, and is input to the arithmetic unit 76 inside the zoom lens 75 as the demand signal S _n representing the digital amount at constant sampling times in the arithmetic unit 74. Further, the position detector 81 detects the position of the lens 79 and outputs the detection result as a digital amount to the counter 82. The counter 82 accumulates this digital amount at any time and stores it as a lens position signal P _n indicating the position of the lens 79 at the current sampling time.

In the third embodiment, similarly to the second embodiment, the lens position signal P _n , which is the position of the lens 79 before the movement, is detected as a digital amount, and the demand 71
Demand signal indicating the operation amount of the lens, that is, the movement amount of the lens 79
S _n is also detected as a digital quantity.

The arithmetic unit 76 arithmetically processes the lens position signal P _n and the demand signal S _n to generate a control signal for the motor 80 to move the lens 79. The process of the arithmetic processing in the arithmetic unit 76 is the same as that of the second embodiment, and finally, the lens speed command value V _n shown in the equation (10) is obtained together with the lens speed U _n shown in the equation (12). Looking for. When calculating the focal length command value F _n displayed by the equation (2), the index a is a =
Let S ^* _n .

Then, the difference between the lens speed command value V _n and the lens speed U _n is obtained, and output to the A / D converter 77 to be converted into an analog signal, which is amplified by the operational amplifier 78 and supplied to the motor 80. Is output. The motor 80 moves the lens 79 to change the angle of view based on this input signal.

[0039]

As described above, in the lens system according to the first and second aspects of the present invention, since the operation amount of the zoom operation member and the change of the image field are constant, the operability can be improved. . Further, since the lens is moved by controlling the driving means by a signal in which an offset value corresponding to the position before the movement of the lens is added, the lens before and after the movement of the lens does not become too large. Can be moved smoothly.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is a flowchart showing a process of calculation processing in a calculation device.

FIG. 3 is a graph showing a function of an offset value having a lens position as a variable.

FIG. 4 is a configuration diagram of a second embodiment.

FIG. 5 is a configuration diagram of a third embodiment.

FIG. 6 is a configuration diagram of a conventional example.

FIG. 7 is a configuration diagram of another conventional example.

[Explanation of symbols]

31, 51, 71 Zoom demand 32, 52 potentiometer 37, 57, 74, 76 arithmetic unit 39 Subtractor 41, 60, 79 lenses 42, 61, 80 motor 44 speed detector 43, 62, 81 position detector 63, 73, 82 counters 72 encoder

Claims (3)

(57) [Claims] 1. A lens system comprising a zoom lens for a television camera and a zoom operating member for operating the zoom lens, and a lens position detecting means for detecting a position of a lens having a zoom function, and driving the lens. Driving means, subtracting means for obtaining a difference signal between the lens command value signal output from the zoom operation member and the lens position signal output from the lens position detecting means, and an offset value is calculated from the lens position signal. Computing means,
Amplifying means for amplifying an output signal of the calculating means, and controlling the lens by using a signal obtained by adding the offset value to a difference signal between the lens command value signal and the lens position signal. And lens system. 2. A lens system comprising a zoom lens for a television camera and a zoom operation member for operating the zoom lens, wherein a lens position command value signal is calculated based on an operation amount of the zoom operation member. An arithmetic means, a lens position detecting means for detecting a position of a lens having a zoom function, a speed detecting means for detecting a moving speed of the lens, and a driving means for driving the lens,
A first signal for obtaining a difference signal between the lens position command value signal and the lens position signal output from the lens position detection means.
Subtracting means, a second calculating means for calculating the offset value from the lens position signal, and a third calculating operation using the signal and the offset value obtained from the first subtracting means. Means, a first amplifying means for amplifying the signal obtained by the third computing means, an output signal from the first amplifying means, and an output signal from the lens speed detecting means.
And a second amplification means for amplifying the signal obtained by the second subtraction means, and the lens position command value signal and the lens position
Using signals obtained by adding the offset value to the difference signal between the signals, a lens system and controls the lens. 3. The lens system according to claim 1, wherein the offset value is given by a function having a position of the lens as a variable.