JPH06167649A - Optical equipment - Google Patents

Abstract

PURPOSE:To shorten the time required to obtain an in-focus screen after power-ON operation by automatically adjusting the focus simultaneously within the time wherein a lens group is moved to a position detected by a position detecting means. CONSTITUTION:Once a stepping motor 137 is driven, an inner focus lens 4 is driven by the output shaft 138 in the direction of the optical axis. The light shield part 156 of a photointerrupter is provided integrally with a moving frame 140 and the photointerrupter 159 has a light emitting element 158 and a light receiving element 157 which are arranged opposite each other. When a focus lens 4 is moved to a starting point, the direction detection result of AF is taken into consideration to determine the moving direction; after the movement is started, an evaluation signal of AF is measured and if there is a focusing point halfway, the distance between the focusing position and a reset position is found. After resetting, the lens is moved at a high speed to the focusing position and normal AF operation is started. This method shorten the time required to obtain the in-focus screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens used for a photographing lens of a video camera or the like, and more particularly to an optical device for moving a lens called inner focus or rear focus to an initial position.

[0002]

2. Description of the Related Art In this type of conventional optical equipment, a front lens focus lens, which moves the first lens group in the optical axis direction by a helicoid, is common, but recently, it is a variable power lens group. A so-called inner focus or rear focus zoom lens that performs focusing using a lens group behind the variator lens is used.

With such a zoom lens, it is possible to shoot at a closer distance than that of the front lens, and it is easy to construct a continuous focus from immediately before the lens to an infinite distance, especially on the wide side. Although various lens types are known, FIG. 14 shows a configuration example in which the rearmost lens group is used for focusing.

In FIG. 4, reference numeral 1 denotes a fixed front lens, and 2
Is a variator lens, 3 is a fixed lens, and 4 is a lens group of a focus lens (compensator). 133 is a guide rod for rotation prevention, 134 is a feed rod of the variator lens 2, 135 is a fixed lens barrel, 136 is a diaphragm unit (inserted at right angles to the paper surface in the illustrated example), and 137 is a focus motor. A step motor 138 is an output shaft of the step motor 137, and is machined to move the lens group 4. Reference numeral 139 denotes a female screw processed portion that meshes with the male screw of the output shaft 138, and is integrated with the moving frame 140 of the lens group 4.

Reference numerals 141 and 142 denote moving frames 14 of the lens group 4.
0 is a guide rod, 143 is a rear plate for positioning and pressing the guide rod, 144 is a relay holder, 145 is a zoom motor, 146 is a speed reducer unit of the zoom motor 145,
Reference numeral 47 is a gear fixed to the output shaft 146a of the speed reducer unit 146, and 148 is a feed rod 1 of the variator lens 2.
The gear is fixed to the gear 34 and meshes with the gear 147.

In the above structure, when the stepping motor 137 is driven, the focus lens 4 moves to the output shaft 13
8 drives in the optical axis direction. When the zoom motor 145 is driven, the feed rod 134 rotates via the gears 147 and 148, and the variator lens 2 moves in the optical axis direction.

FIG. 5 shows the positional relationship between the inner focus variator lens 2 and the focus lens 4 when the positions are plotted on the abscissa and the ordinate, respectively, at each subject distance.

The loci of 150 to 153 correspond to the following object distances, for example.

[0009]

[Table 1] Further, in FIG. 5, it is prohibited to establish the positional relationship between both lenses corresponding to the shaded areas 154 and 155.

As described above, in the inner focus lens, there is a so-called variable focus relationship in which the position to be taken by the focus lens with respect to each variator position during zooming varies depending on the subject distance.

The present applicant has previously proposed a method of controlling the positional relationship between the variator lens and the focus lens during zooming in such a lens. Although detailed explanations are omitted here, some common absolute position encoders for detecting the absolute positions of the variator lens and the focus lens are provided, and the position information of each lens is separately stored in a microcomputer. From the map information shown in FIG. 15, the position of the focus lens to be taken and the moving speed are determined according to the position of the variator lens during zooming.

Of these, as a method of detecting the position of each lens group, in addition to the configuration using a variable resistor,
When using a step motor as an actuator, there is a method of continuously counting the number of input pulses to the step motor.

When such a detecting method is used, the absolute position can be detected by moving the lens group to be detected to a predetermined start position when the power is turned on and starting pulse counting from that position. .

Therefore, another detection switch such as a fort interrupter is usually provided for detecting the starting position (reset position).

FIGS. 6 and 7 show an example in which two such photo interrupters are provided. A light interrupting portion 156 of a photo interrupter is provided integrally with the moving frame 140, and an interrupter 159 has a light emitting element 158 and a light receiving element 157 which are arranged to face each other.

In this embodiment, the interrupters 159 and 160
Is provided, and the entire movement range of the lens group 4 is divided into three regions I, II, and III as shown in FIG. As the starting position, there are two positions of the I-II boundary and the II-III boundary. In both cases, if the address at the start of counting is a and the position is b, then a
It goes without saying that the value of -b is configured so as to match the number of steps required for movement between and.

Further, the interrupters 159 and 1 shown in FIGS.
When 60 is a photo interrupter, the regions I to III are discriminated by encoding as shown in Table 1, where 1 is a light-shielded state and 0 is a non-light-shielded state.

[0018]

[Table 2] If there is only one starting position, the purpose of absolute position detection will be achieved, but by increasing the number of photo interrupters,
If there are two or three or more locations, there is an advantage that the starting position can be speeded up when the power is turned on.

Table 2 shows the position as shown in FIG. 8 and which position is the starting position.

[0020]

[Table 3] In this case, the reset position when the lens group 4 is in the area II is used. By doing this,
It goes without saying that the time to reach that position is shorter than that where there is only one starting position.

[0021]

However, in the above-mentioned conventional example, although a plurality of photo interrupters are provided to shorten the reset positioning time, during this period, the AF operation is inoperative, and AF operation after the reset positioning is completed. If it is difficult to detect the direction of the AF operation (mae pin, ato pin detection) at the reset position because it moves to the operation, (for example, the subject is greatly blurred), it will take time until the focus comes into focus, and the recording start or For shortening the time until it becomes a situation where there is no problem as a recorded image,
It was hard to say that due consideration was given.

An object of the present invention is to provide an optical device which solves the above problems.

[0023]

The present invention comprises a driving means for driving a lens group in the optical axis direction and a position detecting means for detecting at least one position within the moving range of the lens group. By simultaneously performing automatic focus adjustment within the time for moving the lens group to the position detected by the means, which starting position is to be used is determined according to the AF direction detection result. Is evaluated and reflected in the lens movement after the calculation position is set, and the power is turned on.
It is an optical device that shortens the total arrival time to the shooting possible state after N.

[0024]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings.

Table 3 shows the regions I to III shown in FIG.
When the power is turned on when there is a lens group in, which position is the starting position is shown.

[0026]

[Table 4] When the lens group is in the area II, which of the two is selected depends on the result of the AF direction detection (mae pin or at pin).

Usually, the high frequency component F of the Y signal as described above is used.
When searching for the in-focus position, it is common to slightly vibrate the lens group and detect the direction from the vibration phase and the position of the F signal.

Further, the reset positions from the areas I and III are the same as in the conventional example, but in that case also the point that the F signal is launched is different.

FIG. 1 is a flow chart showing the reset operation from the region I. If the lens movement in the downward direction of the Y-axis is the retraction, the lens is driven to the retraction side which is the reset direction in step ST1-1. To be done. Step S
Although the reset position is detected to determine whether at T1-2, if not yet detected, ST1-3, the current F to F ₀ in ST1-4, stores F ₀ before one round to F _1.

Next, in ST1-5, it is determined whether F ₀ -F ₁ is positive or negative. In the case of a positive value, the F value is increased, so that the lens units are moving in the focusing direction while moving in the reset direction. At this time, the value of C is ST1-7
Then, C = 0 is set.

On the other hand, when F ₀ -F becomes negative and what was positive up to that point becomes negative, it can be assumed that the focus lens position has been passed at that position. Further, in the case of a negative value from the beginning, it can be assumed that the position of the lens group at the time of starting the reset operation is already at the focusing lens position on the projecting side from that position.

In any case, the position where F ₀ -F ₁ becomes negative _first is set to C = 0, and the number of pulses (input pulse to the step motor) is continuously counted from that position until the end of reset (ST1). -6).

After the reset position is detected, that is, ST1-2
If the result of the determination is YES, the reset address R ₀₁ (this R ₀₁ is predetermined) that is the starting value is read (S
T1-8), and thereafter, if n pulses are moved in the extending direction, the position is (R ₀₁ + n), and if n pulses are moved in the retracting direction, (R ₀₁ -n), the absolute position of the lens group is known ( ST1-9). However, it is assumed that the value of C is counted as + even in the folding direction. Here, it calculates the R ₀₁ + C as R _1.

Next, in ST1-10, the lens unit is forcibly moved so that R becomes the position of R ₁ , and then the normal routine is first drawn.

By doing so, the position of the lens group at the time of the AF subsequent to the normal AF is put into the AF from a position which seems to be in focus that can be detected during the reset, or a position closer to the focus than the reset position. The time from turning on to resetting to reaching the focused state can be shortened compared to conventional equipment.

FIG. 2 shows the reset from the region III, which is basically the same as the reset operation from the region I, and FIG. 3 which performs the reset operation of steps ST2-1 to ST2-10 is the reset from the region II. 7 is a flowchart showing the operation. First, in ST3-1, detection of mae pin or ato pin is performed by slightly vibrating the lens group. ST3
At -2, distribution is performed based on the detection result. If the detection result is NO, the driving in the feeding direction is performed in ST3-3, and if the detection result is YES, that is, if the mae pin is S
The operation after T3-4 will be described.

When the detection result of ST3-2 is maepin,
As the reset direction, the focus lens position is moved to the side where it exists, so the drive is performed in the folding direction (ST3-4).
Then, in ST3-5, it is determined whether or not it is the reset position, and if it is not the reset position, ST3-6 to ST3-8
Then, as in the case of FIG. 1, the difference between the current F ₀ and F _{1 one} cycle before is found, and in the case of a positive value, C = 0 in ST3-9, from the time point of changing from positive to negative, in ST3-10. Then start counting C. After reaching the reset position, ST3-11-ST
In 3-13, the same operation as in the case of FIG. 1 is performed.

In the embodiment, the position where there are two starting positions is shown, which starting position is to be used is determined according to the AF direction detection result, and the AF is evaluated even during the movement to the starting position. This evaluation of AF is a method in which a peak signal of a high frequency component of a Y signal which is generally used in a video camera is used as a focusing lens position for focusing, and when the value of the training component of this Y signal is F, it is calculated. It indicates that F is measured even during movement for positioning.

Therefore, as a premise for implementing the present invention,
It is premised that the start-up of the image pickup by the CCD or the like is sufficiently quicker than the operation for calculating the initial position. Further, even if there is only one starting position as in the prior art, it is possible to take the same configuration as the embodiment.

[0040]

As described above, according to the present invention,
When moving the inner focus lens to the starting position: The AF direction detection result is considered in determining the moving direction.

.. After the movement is started, the AF evaluation signal (high-frequency component of the Y signal) is measured, and if there is a focus position on the way, the distance between the focus position and the reset position is obtained.

.. In the case of, after resetting, moving to the in-focus position at high speed, and then continuing to the normal AF operation, the time until the in-focus screen is obtained after the power is turned on can be greatly shortened. is there.

[Brief description of drawings]

FIG. 1 is a flowchart showing an operation from an area I of an optical device according to a first embodiment of the present invention.

FIG. 2 is a flow chart showing the operation from the area III of the optical device in the first embodiment of the present invention.

FIG. 3 is a flowchart showing an operation from the area II of the optical device according to the first embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view showing a conventional optical device.

FIG. 5 is an explanatory diagram of a positional relationship between a variator lens and an RR lens.

FIG. 6 is a side view illustrating the arrangement of photo interrupters.

FIG. 7 is a front view of FIG.

FIG. 8 is an explanatory diagram of a divided area showing a moving range of a lens group.

[Explanation of symbols]

 2 variator lens (lens group) 4 focus lens (lens group) 137 focus motor (driving means) 145 zoom motor (driving means) 159 interrupter (position detecting means) 160 interrupter (position detecting means)

Claims (1)

[Claims] 1. A driving means for driving a lens group in the optical axis direction, and a position detecting means for detecting at least one position within a moving range of the lens group, to a position detected by the position detecting means. An optical device which performs automatic focus adjustment at the same time within the time for moving the lens groups.