JP3382402B2 - Lens position control device and optical device using the same - 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 position control device and an optical device using the same, and more particularly, to a variation in environmental temperature of an initial position in the optical axis direction of a movable part having a movable lens group for zooming and focusing. It is suitable for a video camera, a 35 mm film camera, and the like, which can be appropriately set according to the above and can obtain a high-quality image.

[0002]

2. Description of the Related Art Conventionally, zoom lenses are often used in optical devices such as 35 mm film cameras and video cameras. As a zoom type of such a zoom lens, a lens group (focus lens) for focus adjustment is used for the first lens group on the object side, and a lens group (variator) for zooming is used for the second lens group. 4 group of so-called front lens focus type, which uses a lens group (compensator) for correcting image plane variation due to zooming in the 3rd group, and uses an image forming (relay) lens group in the 4th group. There is a zoom lens.

On the other hand, recently, in order to reduce the size and weight of a zoom lens and enable shooting at a closer range, a lens group behind the variator lens, for example, a compensator lens is used for focusing, that is, a so-called rear focus type. A zoom lens (hereinafter, such a type of zoom lens is referred to as an "RFZ zoom lens") is often used. In addition, a plastic lens is used as part of the lens system in order to provide a more inexpensive zoom lens. In the RFZ zoom lens, the position of the compensator focused on a predetermined variator position is uniquely determined by the subject distance.

FIG. 9 is an explanatory view showing the positional relationship in the optical axis direction for focusing of the variator and compensator for each subject distance in the RFZ zoom lens. The horizontal axis represents the position of the variator in the optical axis direction, and the vertical axis represents the position of the compensator in the optical axis direction. The zooming operation of the zoom lens is performed by changing the position of the variator. However, in order to perform the zooming operation while maintaining the focus, the lens position relationship of the compensator for focusing shown in FIG. It needs to be maintained.

Next, a conventional RFZ will be described with reference to FIGS.
The zooming operation of the zoom lens will be described.

FIG. 10 is a block diagram of the essential parts of a video lens using an RFZ zoom lens. Reference numeral 101 is an RFZ zoom lens, 101a is a fixed front lens group, 101b
Is a variator lens group, 101c is a fixed lens group, 1
Reference numeral 01d denotes a focusing (compensator) lens group that corrects an image plane variation due to zooming and performs focusing. Reference numeral 102 is an image pickup device such as a CCD, 103 is an aperture meter, 104 is an aperture encoder for detecting an aperture value, and for example, an output from a hall element provided in the aperture meter 103 is used.

Reference numeral 105 denotes a camera processing circuit, which is the CCD 1
The Y signal from 02 is taken into the AF circuit 106. The AF circuit 106 determines whether it is in-focus or out-of-focus, and when it is out of focus, determines whether it is front focus or rear focus, and the extent of non-focus (TV-AF). AF
The result from the circuit 106 is captured by the CPU 107.

Reference numeral 108 denotes a power-on reset circuit, which is a power source O
Performs various reset operations at N hours. This includes initial position setting (detection) of each lens position. As the method of setting (detecting) the initial position of the lens, there are an optical means using a photo interrupter and a magnetic means using a hall element.

Next, one means for setting (detecting) the initial position of the lens using the photo interrupter will be described with reference to FIGS.

FIG. 11 is a block diagram using a photo interrupter. In the figure, the compensator 101d held by the lens holder 130 is composed of two guide bars 131.
It is supported by a, 131b (131) so as to be movable in the optical axis direction. Reference numeral 132 denotes a photo interrupter composed of a light emitting element and a light receiving element facing each other, which is fixed to a lens barrel (not shown) and provided on the lens holder 130.
3 intervenes between the light emitting element and the light receiving element facing each other.

FIG. 12 shows a detection circuit of the photo interrupter 132, which applies a predetermined current to the light emitting element 134 and applies a predetermined voltage to the light receiving element 135. Thereby, the light receiving element 1
A predetermined output voltage Vo can be obtained from the output terminal So according to the amount of light received by the light source 35.

FIG. 13 is an explanatory view showing an example of the output voltage characteristic from the photo interrupter 132. The horizontal axis represents the position of the compensator in the optical axis direction, and the vertical axis represents the output voltage from the photo interrupter 132. The initial position is set (detected) by comparing the output voltage Vo with the preset comparison voltage value Vs.
This position is used as the initial position. One example of magnetic lens initial position setting (detection) is to provide a Hall element on either one of the lens holder and the lens barrel, and to provide a magnet with the border between the N and S poles facing the Hall element on the other side. The position where the output of the Hall element becomes zero at the boundary between the N pole and the S pole is used as the initial position.

Returning to FIG. 10, 109 is a zoom switch for transmitting the contents to the CPU 107. Reference numeral 110 denotes a zoom motor, which is, for example, a step motor, and a drive pulse is transmitted from the CPU 107 to the zoom motor driver 111 and rotated according to the number of pulses to drive the variator lens group 101b via a transmission mechanism (not shown). Further, the number of drive pulses of the step motor is continuously counted in the CPU 107 based on the above-mentioned lens initial position and used as an absolute position encoder of the variator lens group 101b. 112
Is a focus motor, and a stepper motor is used like the zoom motor. Reference numeral 113 denotes a focus motor driver, which drives the focus lens group 101d in the same manner as the above-mentioned drive of the variator lens group. Reference numeral 114 denotes data for driving and controlling each lens while maintaining a lens relationship in which the lens is always in focus according to the subject distance during zooming.
It is held in OM.

The data 114 is, for example, the variator lens group 101b at an arbitrary subject distance as shown in FIG.
Is a value relating to the positional relationship (cam locus) of the focus lens group 101d that is in focus with respect to the position of. Data 114
Holds a cam locus for several types of subject distances.
For example, if the zoom switch 109 is operated during shooting,
When zooming to the tele side from the respective lens positions shown by the positions (V1, RR1) in FIG. 9, the tele side lens position V2 is obtained from the preset position V1 of the variator lens group 101b, and the data 114 From the position V2 of the variator 101b of the focus lens group 101d
The position RR2 with respect to
2, RR2). If the subject distance is not held in the data 114, the zoom operation is performed by interpolating from the subject distance cam locus held in the data 114.

[0015]

In the conventional RFZ zoom lens, it is important to accurately set (detect) the initial position (reference position) of each lens in order to perform the zooming operation accurately. . However, if there is a temperature change in the environment or heat is generated by an actuator or electric board attached to the lens barrel, a temperature change is caused in the lens barrel, and as a result, the position of the variator or compensator is displaced. Come on. In particular, when a part of the lens is made of a plastic lens, the positional deviation due to the temperature change becomes remarkable.

FIG. 14 is an explanatory diagram showing a lens position shift due to a temperature change of an INF cam locus at a subject distance of infinity (INF) when a part of the RFZ zoom lens is composed of a plastic lens. IN like this
The F-cam locus is ± if there is a temperature change relative to room temperature (25 ° C)
A displacement of several tens of μm is generated, and the above-described variable-magnification operation method traces a cam locus with a different subject distance.
There is a problem in that an image is blurred during scaling.

In order to avoid this, some proposals have been made to provide temperature detecting means and position deviation amount data due to temperature change, and use the detection result of temperature to correct the position deviation due to temperature. There are problems such as an increase in the amount of held data and a need for complicated correction calculation (control).

According to the present invention, by appropriately setting the initial setting of the movable portion having the movable lens group for moving on the optical axis with respect to the fluctuation of the environmental temperature, an image of good image quality can be always obtained even if the environmental change occurs. An object of the present invention is to provide a lens position control device suitable for an optical device such as a video camera to be obtained and an optical device using the lens position control device.

[0019]

According to another aspect of the present invention, there is provided a lens position control device including a lens barrel, a movable ring which holds a movable lens and is movable in the optical axis direction, and a movable ring incorporated in the lens barrel. Driving means, position detecting means for detecting a relative position based on the initial position of the moving ring, initial position setting means for setting the initial position of the moving ring, and a signal from the position detecting means. Position control means for controlling the position of the moving ring from the initial position based on the initial position, and the initial position setting means has a temperature detection part for detecting a change in environmental temperature, and the temperature from the temperature detection part. An output that changes due to a change is used as a comparison output, the comparison output is compared with the output from the position detecting means, and the initial position of the moving ring is changed and set according to the comparison result. According to the invention of claim 2, in the invention of claim 1, after the initial position setting means changes and sets the initial position in accordance with the comparison result,
The comparison output from the temperature detection unit is evaluated every predetermined time, and when the comparison output changes from a predetermined amount, the initial position is changed and set again according to the comparison result. .

A lens position control device according to a third aspect of the present invention comprises a lens barrel, a movable ring which holds the movable lens and is movably installed in the lens barrel so as to be movable in the optical axis direction, and drive means for driving the movable ring. A position detecting means for detecting a relative position based on the initial position of the moving ring, an initial position setting means for setting the initial position of the moving ring, and an initial position based on a signal from the position detecting means. A position control means for controlling the position of the moving ring, wherein the initial position setting means holds the position detection means on the lens barrel through a member that changes in the optical axis direction with a change in environmental temperature, It is characterized in that the initial position of the moving ring is set by adjusting the output signal obtained from the position detecting means.

The optical device according to the invention of claim 4 is the optical device according to claim 1,
It is characterized by having the lens position control device described in any one of 2 and 3.

[0022]

Embodiment 1 FIG. 1 is a schematic view of the essential portions of Embodiment 1 of the present invention.

In the figure, reference numeral 1 denotes an RFZ zoom lens, which is a front lens group 1a fixed in order from the object side, a variator lens group 1b for zooming, a fixed lens group 1c, and correction of image plane variation due to zooming. And a focusing (compensator) lens group 1d for focusing. Reference numeral 2 is an image pickup device such as a CCD, 3 is an aperture meter, 4 is an aperture encoder for detecting an aperture value, and uses an output signal from a hall element provided in the aperture meter 3, for example.

Reference numeral 5 denotes a camera processing circuit, which takes in the Y signal from the CCD 2 into the AF circuit 6. 7 is CP
U (position control means) and 8 are power-on reset circuits which perform various reset operations when the power is on. Reference numeral 9 denotes an initial position setting (detecting) means for setting the initial position of the moving lens, that is, the initial position of the moving ring (moving lens barrel, movable part) holding the moving lens. The initial position setting (detecting) means 9 will be described in detail later.

Numeral 10 is a zoom switch whose contents are stored in the CPU.
I have told 7. Reference numeral 11 denotes a zoom motor (driving means), which is composed of, for example, a step motor, and a driving pulse is transmitted from the CPU 7 to the zoom motor driver 12 and rotated according to the number of pulses to drive the variator lens group 1b through a transmission mechanism (not shown). There is. The number of drive pulses of the step motor 11 is continuously counted in the CPU 7 with the initial position of the moving lens as a reference, and the variator lens group 1b
It is used as an encoder for absolute position detection. Thirteen
The focus motor is a step motor similar to the zoom motor 11. In this embodiment, the step motor and the CPU 7 form an element of the position detecting means.

Reference numeral 14 is a focus motor driver,
The focus lens group 1d is driven in the same manner as the above-mentioned variator lens group 1b. Reference numeral 15 is data for driving and controlling each lens while maintaining the lens relationship so that the lens is always in focus according to the subject distance during zooming, and is stored in the ROM or the like.

In the figure, an example in which a step motor is used for driving each lens and a lens position detecting means is described, but another electromagnetic motor (DC motor, voice coil motor, etc.) or an ultrasonic motor is used for driving the lens. Etc., an optical encoder combining a light emitting diode (IRED) and a position sensor (PSD) for relative position detection,
Then, a magnetic encoder or the like in which a magnet magnetized with multiple poles and a magnetic sensitive element (MR element, Hall element) are combined may be used.

2A and 2B are explanatory views of the initial position setting means 9 of this embodiment. In the present embodiment, an example in which the photo interrupter 23 and the light shielding plate 24 are used is shown. In FIG. 2A, the compensator 1d held by the lens holder (moving ring) 21 has two guide bars 22a, 22a.
It is supported by b (22) so as to be movable in the optical axis direction. 23
Is a photo interrupter composed of a light emitting element and a light receiving element facing each other, and is fixed to a lens barrel (not shown) so that a light shielding plate 24 provided on the lens holder 21 intervenes between the light emitting element and the light receiving element facing each other. There is.

FIG. 2B is an explanatory diagram of the detection circuit in the initial position setting means 9. In this embodiment, a predetermined current is passed through the light emitting element 25 and a predetermined voltage is applied to the light receiving element 26. As a result, a predetermined output voltage Vo is obtained from the output terminal So according to the amount of light received by the light receiving element 26.

FIG. 3 shows the photo interrupter 23 shown in FIG.
FIG. 3 is an explanatory diagram showing an example of output voltage characteristics from FIG. The horizontal axis represents the position of the compensator as a moving lens in the optical axis direction, and the vertical axis represents the output voltage Vo from the light receiving element 26. In the initial position setting (detection), the comparator 27 compares the output voltage Vo and the comparison voltage Vs which changes depending on the environmental temperature.
And the position where the output from the comparator 27 has changed is detected by the CPU 7 and the comparison is performed.

In this embodiment, the value of the reference voltage Vs is set by using the temperature sensitive resistor 28. The comparison voltage Vs changes with the temperature change, as shown in the right side of FIG. Therefore, when the temperature is a temperature Tb which is deviated from Ta by ΔT, the comparison voltage changes from Vsa to Vsb, and the initial setting position of the moving lens changes from position Ra to position Rb. That is, the initial position of the moving lens is ΔR = Ra−Rb due to the temperature shift of ΔT.
It will only be shifted.

FIG. 4 shows a relational diagram of lens position deviation due to temperature change of the locus of the INF cam when the object distance is infinity (INF) when a part of the lenses of the RFZ zoom lens is composed of plastic lenses. As described above, the lens position shift with respect to the temperature change is substantially linear because it is governed by the linear expansion coefficient of the plastic lens. Therefore, in this embodiment, the temperature detecting means of the initial position setting means 9 detects the temperature, and the degree of change (ΔR / Δ) with respect to the temperature at this time is detected.
T) is set to have an opposite phase according to the degree of deviation with respect to the temperature of the moving lens. Thus, the initial position of the moving lens is easily changed according to the temperature change, and the lens position shift due to the temperature change is corrected.

In this embodiment, after the initial position of the moving lens is once set as described above, the value of the comparison voltage Vs is evaluated every predetermined time and when the value is deviated by a predetermined amount, or the comparator 27
If the output from changes, the initial position of the moving lens is reset. Thus, the lens position shift due to the temperature change is constantly corrected. Although the configuration using the photo interrupter and the light shielding plate as the initial position setting means is described in the present embodiment, it may be configured by using a magnet in which the boundary between the hall element and the N and S poles is directed to the hall element.

Next, a reference example will be described with reference to FIGS.

In the reference example, the initial position setting means outputs the voltage Vo according to the position of the compensator (movable part), and the position which becomes the reference voltage Vs is set as the initial position. A temperature detecting means for detecting the temperature of the lens system is provided, and the output voltage Vo is changed based on the result of the temperature detection, thereby changing the initial lens position according to the temperature change of the lens system, and the lens position shift due to the temperature change. Is easily corrected.

The configuration of the lens position control device of the present reference example is the same as that of the first embodiment, and therefore its explanation is omitted.

The initial position setting means 9 is composed of a photo interrupter and a light shielding plate as in the first embodiment. FIG. 5 is an explanatory diagram of the detection circuit of the second embodiment. A predetermined current is passed through the light emitting element 25 and a predetermined voltage is applied to the light receiving element 26 .
Here, the resistor Rh that determines the amount of current flowing through the light emitting element 25
Uses a temperature-sensitive resistor. As a result, the light emission amount of the light emitting element 25 changes due to the temperature change, and the output voltage Vo from the output terminal So corresponding to the light receiving amount of the light receiving element 26 changes due to the temperature change, as shown in FIG.

This output voltage Vo is used for initial position setting (detection).
And a predetermined reference voltage Vs are compared by the comparator 27, and the position where the output from the comparator 27 has changed is determined by the CPU.
It is detected at 7. Therefore, when the temperature is the temperature Tb which is deviated from Ta by ΔT, the initial setting position of the lens is the position Rb. That is, the initial position of the lens shifts by ΔR = Ra−Rb due to the temperature shift of ΔT. In the present embodiment, similarly to the first embodiment, the initial position setting means 9 sets the degree of change (ΔR / ΔT) with respect to temperature in accordance with the degree of deviation with respect to the temperature of the lens, and sets it so as to have an opposite phase,
Thus, the lens initial position is easily changed according to the temperature change of the lens to correct the lens position shift due to the temperature change.

In the reference example, after the initial position of the lens is once set as described above, the value of the reference voltage Vs is evaluated every predetermined time and when the value is deviated by a predetermined amount, or when the output from the comparator 27 changes, The initial lens position is being reset. Thus, the lens position shift due to the temperature change is constantly corrected. In this reference example, the configuration in which the photo interrupter and the light shielding plate are used as the lens initial position setting means is described, but it may be configured using a magnet in which the boundary between the Hall element and the N and S poles is directed to the Hall element. .

Next, a second embodiment of this embodiment will be described with reference to FIGS. 7 and 8. In this embodiment, the initial position setting means 9
By fixing a part of the lens through a member that deforms in the optical axis direction depending on the temperature, the lens initial position is changed according to the temperature change of the lens, whereby the lens position shift due to the temperature change is easily corrected.

The configuration of the lens position control device of the present embodiment is the same as that of the first embodiment, and therefore its explanation is omitted.

FIG. 7 is a schematic view of the initial position setting means,
FIG. 7A shows an example constituted by the photo interrupter 23 and the light shielding plate 24. Insert the compensator 1d held in the lens holder 21 into two guide rods 22a, 22b (2
In 2), it is supported so as to be movable in the optical axis direction. Reference numeral 23 denotes a photo interrupter composed of a light emitting element and a light receiving element which face each other, and is fixed to a lens barrel (not shown) via a member 31 (a synthetic resin having a large linear expansion coefficient or a bimetal element) which is deformed in the optical axis direction by temperature, A light shielding plate 24 provided on the lens holder 21 is interposed between the light emitting element and the light receiving element facing each other.

FIG. 7B is an explanatory diagram of the detection circuit in the initial position setting means 9. In this embodiment, a predetermined current is passed through the light emitting element 25 and a predetermined voltage is applied to the light receiving element 26. As a result, a predetermined output voltage Vo is obtained from the output terminal So according to the amount of light received by the light receiving element 26.

FIG. 8A is an explanatory view showing an example of the output voltage characteristic from the photo interrupter 23 of this embodiment. The horizontal axis represents the position of the compensator in the optical axis direction, and the vertical axis represents the output voltage Vo from the light receiving element 26. This characteristic is a characteristic including the temperature-displacement characteristic of the connecting member 31 shown in FIG. In the initial position setting (detection), the output voltage Vo and the comparison voltage value Vs are compared by the comparator 27, and the position where the output from the comparator 27 is changed is determined by the CPU.
It is detected at 7.

Therefore, when the temperature is the temperature Tb which is deviated from Ta by ΔT, the initial setting position of the lens is the position Rb. That is, due to the temperature shift of ΔT, the initial lens position is ΔR =
Only Ra-Rb will shift. In the present embodiment, as in the first embodiment, the initial position setting means 9 sets the degree of change (ΔR / ΔT) with respect to the temperature in accordance with the degree of deviation with respect to the temperature of the lens so as to have the opposite phase. The lens initial position is changed according to the temperature change, and the lens position shift due to the temperature change is corrected.

In this embodiment, after the initial position of the lens is once set as described above, the value of the comparison voltage Vs is evaluated every predetermined time and when the output voltage from the comparator 27 changes by a predetermined amount, or when the output from the comparator 27 changes, the lens The initial position is being reset. Thus, the lens position shift due to the temperature change is constantly corrected. Although the configuration using the photo interrupter and the light shielding plate as the lens initial position setting means is described in the present embodiment, it may be configured by using a magnet in which the boundary between the Hall element and the N and S poles is directed to the Hall element. .

[0047]

As described above, according to the present invention, by appropriately setting the initial setting of the movable part having the movable lens group for moving on the optical axis with respect to the fluctuation of the environmental temperature, there is no environmental change. However, it is possible to achieve a lens position control device suitable for an optical device such as a video camera and an optical device using the same, which can always obtain an image of good quality.

In particular, according to the present invention, the output from the lens initial position setting means is changed in accordance with the temperature change, and the degree of change with respect to the temperature of the initial position setting means is adjusted to the degree of deviation with respect to the temperature of the lens so as to be in the opposite phase. By doing so, it is possible to easily change the initial position of the lens according to the temperature change of the lens portion and correct the lens position deviation due to the temperature change.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

2 is an explanatory view of the initial position setting means of FIG.

FIG. 3 is an output characteristic diagram of the initial position setting means of FIG.

FIG. 4 is an explanatory diagram of an INF cam locus of the RFZ zoom lens.

FIG. 5 is an explanatory diagram of a detection circuit of a reference example.

FIG. 6 is an output characteristic diagram of an initial position setting unit of a reference example.

FIG. 7 is an explanatory diagram of an initial position setting unit according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram of an initial position setting unit according to the second embodiment of the present invention.

FIG. 9 is an explanatory diagram of a cam locus of the RFZ zoom lens.

FIG. 10 is a schematic view of a main part of a conventional video lens.

11 is an explanatory view of the initial position setting means of FIG.

FIG. 12 is an explanatory diagram of a part of FIG. 11.

13 is an explanatory diagram of a part of FIG.

FIG. 14 is an explanatory diagram of a cam locus of the RFZ zoom lens due to temperature change.

[Explanation of symbols]

1 RFZ zoom lens 2 CCD 3 Aperture meter 4 aperture encoder 5 Camera processing circuit 6 AF circuit 7 CPU 8 Power-on reset 9 Initial position setting means 10 Zoom switch 11,13 motor 12 Zoom motor driver 14 Focus motor driver 15 data

Continuation of front page (56) Reference JP-A-5-323173 (JP, A) JP-A-6-289275 (JP, A) JP-A-6-308365 (JP, A) JP-A-5-93832 (JP , A) JP 5-188264 (JP, A) JP 1-259310 (JP, A) JP 2-1524 (JP, A) JP 2-197808 (JP, A) JP 6-160695 (JP, A) JP-A-7-301738 (JP, A) Actually developed 62-158431 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 7/02 -7/10

Claims (4)

(57) [Claims] And 1. A lens barrel, and moving ring incorporated in the lens barrel movably in the optical axis direction holding the moving lens, driving means for driving the moving ring, relative to the initial position of the moving ring controlling a position detecting means for detecting the relative position, the initial position setting means for setting an initial position of the moving ring, the position of the moving ring from initial position based on a signal from said position detecting means as a A position control means, wherein the initial position setting means is a temperature detecting a change in environmental temperature.
It has a detector and changes depending on the temperature change from the temperature detector.
Output as the comparison output, and the comparison output and the position detection means
The output from the mobile ring is compared according to the result of this comparison.
A lens position control device characterized by changing and setting the initial position . 2. The initial position setting means is the initial position.
After changing and setting according to the comparison result, the comparison output from the temperature detection unit is evaluated every predetermined time.
If this comparison output changes from a predetermined amount, the initial position
The lens position control device according to claim 1, wherein the position is changed and set again according to the comparison result . 3. A lens barrel, Assembled in the lens barrel so that it holds the movable lens and can move in the optical axis direction
With a moving ring Drive means for driving the moving ring, Relative position is detected with reference to the initial position of the moving ring.
Position detection means, Initial position setting means for setting the initial position of the moving ring
When, Based on the signal from the position detecting means,
Position control means for controlling the position of the moving ring, The initial position setting means controls the position detecting means to change the ambient temperature.
Holds in the lens barrel via a member that changes in the optical axis direction with
The output signal obtained from the position detecting means.
Is used to set the initial position of the moving ring.
Lens position control device. 4. The register according to claim 1, 2, or 3.
Optical device having a lens position control device
vessel.