JPS61282812A - Lens position detecting device - Google Patents

Abstract

PURPOSE:To detect the position of a lens under non-contacting state and to increase durability by fixing a focus ring provided to the outer periphery of a lens barrel body and a photosensor which is provided to a zoom ring and faces a light and shade pattern part at specific positions. CONSTITUTION:Light and shade pattern parts 11a-11c and 12a and 12b are provided on the circumferences of the focusing 11 and zoom lens 12 provided to the lens barrel body 19 so that they shift axially. Photosensors 13 and 14, and 15 and 16 consisting of light emitting parts and photodetecting parts for detecting light and shade are fitted to a fixed member 18. The focus ring 11 is stored to detect the position of the focus ring 11 from the combination of the presence and absence of outputs of the photosensors 13 and 14, thereby detecting the position of the lens. The position of a zoom lens is detected similarly as to the zoom ring 12. Thus, the detection is performed under non-contacting state and durability and stability are improved.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is applicable to video cameras or camera-integrated video cameras.
The present invention relates to a lens position detection device for an autofocus lens that can be applied to a precoder (hereinafter referred to as an integrated VTR).

BACKGROUND OF THE INVENTION In recent years, video tape recorders (hereinafter referred to as VTRs) have become increasingly popular. As video cameras and camera-integrated VTRs become smaller and lighter, opportunities for enjoying camera photography are increasing. When taking pictures with a camera, an autofocus (hereinafter referred to as AF) mechanism is becoming an essential element because it allows easy and reliable photography. A
In order to operate the F mechanism accurately, it is necessary to detect the states of focus, zoom, etc., and a lens position detection device is required for this purpose.

An example of a conventional lens position detection device will be described below with reference to the drawings.

FIG. 5 is a sectional view showing the configuration of a conventional lens position detection device used to detect the focus state. Further, FIG. 5 is a partially cutaway side view of FIG. 6. In FIG. 5, the focus ring 2 is rotatable around the lens optical axis 7. As shown in FIG. A drive pin 2+L is provided protruding from the outer circumference of the focus ring 2, and loosely fits into the groove 3a of the slider 3 to which the contact 4 is fixed. Further, on both sides of the lens position detection device 1, a circular guide groove 5a is provided with the lens optical axis 7 as the center, and the slider 3 is loosely fitted into this guide groove, It is rotatable. The tip 4a of the contact 4 fixed to the slider 3 is in contact with the inner surface of a printed circuit board (hereinafter referred to as P board) 6 held inside the case 5.

Therefore, when the focus ring 2 is rotated about the lens optical axis 7, the tip 4a of the contact 4 slides on the P plate 6. Incidentally, as shown in FIG. 6, conductive parts sa, sb, and ec are provided on the P plate 6 at positions facing the tips 4a of the contacts 4.

The operation of the conventional lens position detection device configured as described above will be described below.

In FIG. 5, the focus ring 2 rotates about the lens optical axis 7 in the opposite direction to the direction indicated by the arrow, and the tip 4 of the contact point 4 &
When is at position X, the conductive portion 6a and the conductive portion 6b are electrically connected through the contact point 4, as is clear from FIG. Similarly, when the tip 4a of the contact 4 rotates in the input direction and is between the X and Y positions, there is no conduction between the conductive parts 61L, 6b, and 6c.

Next, Y! :The conductive parts 62L and 60 are electrically connected between the X positions. And, at the Z position, the conductive part 62L.

6b and 60 are all conductive. Therefore, if the X position is the slope of the focus, the Z position is the closest distance, and the Y position is approximately midway between the slope and the closest distance, then
By checking the conduction state between the conductive parts ea, sb, and ecO, the position of the lens when the focus is operated can be detected. Furthermore, a similar method can be used to detect the lens position when the zoom is operated.

Problems to be Solved by the Invention However, in the above configuration, the slider 3. Contact point 4. P board 6. Since the case 5 is located there and the contact point 4 rotates together with the focus ring 2 (rotation angle is about 1oo'), it is very large in the radial and circumferential directions, and also in terms of weight. It gets heavy. In addition, the number of parts is large, precision is required, and assembly man-hours are required, resulting in an increase in costs. Therefore, this becomes a major hindrance to efforts to reduce the size, weight, and cost of recent video cameras or camera-integrated VTRs. In addition, in the above configuration, the position is detected by contact between the contact 4 and the P plate 6, and the tip 4a of the contact 4 is always sliding on the P plate, so there are problems with durability, stability, etc. Very problematic. Elements such as durability and stability are very important for video cameras and camera-integrated VTRs that are often used continuously for long periods of time.

The present invention solves the above-mentioned problems, and aims to provide a lens position detection device that is small, lightweight, low cost, and highly durable and stable.

Means for Solving the Problems In order to solve the above-mentioned problems, the lens position detection device of the present invention rotates a lens barrel main body and the outer periphery of the lens barrel main body by a predetermined angle. A focus ring that focuses on a surface, a zoom ring that changes the focal length of a lens, a light and dark pattern portion provided on the circumference of at least one of the focus ring and the zoom ring, and a position facing the light and dark pattern portion. The photo sensor is provided with a photo sensor disposed in the photo sensor, and a fixing means for fixing the photo sensor in a predetermined position.

Effect The present invention has the above-described configuration, so that the position detection of the lens can be performed by
This can be done optically without contact by detecting the light and dark pattern provided on the outer periphery of the focus ring or zoom ring using a photosensor fixed at a predetermined position. Therefore, extremely durable and stable detection is possible. Furthermore, due to recent advances in semiconductor technology, photosensors have become extremely small and low cost. On the other hand, the light and dark pattern can be printed or pasted directly on the focus ring or zoom ring, which reduces the number of parts and the number of assembly steps, making it possible to detect the position of the lens with an extremely small size, weight, and low cost. It will be possible.

Embodiment Hereinafter, a lens position detection device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a side view showing the configuration of an embodiment of the present invention.
FIG. 2 is a front view of FIG. 1. In FIG. 1, a focus ring 11 and a zoom ring 12
are respectively rotatable by a predetermined angle on the outer periphery of the lens barrel main body 19 about the lens optical axis 20. Then, on each circumference, light and dark pattern portions 1111.11b, 1
10 and light and dark pattern portions 122L and 12b are provided.

A first photosensor 13 is located at a position opposite to the light and dark pattern portions 111L and 11b.
0, the second photosensor 14 detects the bright and dark pattern portion 1.
The third photosensor 15 for 2& and the fourth photosensor 16 for the bright and dark pattern portion 12bl/c are arranged so that adjacent photosensors are not placed side by side on the same line orthogonal to the lens optical axis, as shown in FIG. is arranged on the P plate 17. Then, the P plate 17 is attached to the lens barrel main body 19 via the fixing member 18, for example, by screws 21 and 22.
is fixed. In addition, the photo sensor is shown in Figure 3.
The photosensor 13 shown in FIG. 1 is composed of one light emitting section 132L and one light receiving section 13b, and this structure is exactly the same for the second, third, and fourth photosensors 14, 16, and 16.

Taking as an example the case where the lens position detection device of this embodiment configured as described above is used to detect the focus state, its operation will be explained below with reference to FIGS. 1 to 4. . As shown in FIG. 3, light is constantly emitted from the light emitting section 13 of the photosensor 13 fixed at a predetermined position. The light emitted from the light emitting section 131L passes through the path H,
The position on the outer circumference of the focus ring 11 is reached. If the reflectance of the portion at position I on the focus ring 11 is high (for example, white), the light is reflected at position I.

In order to enter the light receiving section 13b through the path J, the light receiving section 1
3b can detect the light from the light emitting section 132L.

On the other hand, when the reflectance of the 1-position part is low (for example, black), the light emitted from the light emitting part 132L is hardly reflected by the position part, so the light receiving part 13b cannot detect the light from the light emitting part 13&. Therefore, by providing a bright and dark pattern around the focus ring 11, it is possible to detect the focus state by checking whether the light receiving section 13b can detect the light emitted from the source/tip section 13&. be.

In FIG. 1, when the focus ring 11 is at position S, if the light and dark pattern parts 11a, 11b, and 11c are parts with high reflectance, the first photosensor 13 and the second photosensor 14 detect light. be able to. , Incidentally, the light and dark pattern portions 11&, 11b and the light and dark pattern 110 are arranged around one circumference by an amount corresponding to the offset amount l between the first photosensor 13 and the second photosensor 14 shown in FIGS. 2 and 4. It is provided shifted by m in the direction.

Next, as shown in FIG. 2, the focus ring rotates in the direction B, and between the position S and the position shown in FIG. 1, the second photosensor 14 detects the light reflected by the bright and dark pattern 11c. Although you can.

The first photosensor 13 cannot detect light. Similarly, between position T and position U, the first photosensor 13, the second photosensor
It cannot be detected by the photo sensor 14 either. At position U, only the first photosensor 13 can detect light.

Therefore, if the position S is the closest focus position, the position ■ is the ringing position, and the position T is approximately halfway between the two, will the first photosensor 13 and the second photosensor 14 be able to detect light? By checking this, the position of the lens when the focus is operated can be detected. The same method can also be used to detect the position of the lens when the zoom is operated.

As described above, in this embodiment, the position of the lens is detected in an optical non-contact manner by detecting light with a photo sensor using the light and dark pattern provided around the focus ring 11 and zoom ring 12. It has extremely high durability and stability. Furthermore, as is clear from a comparison with the conventional example shown in Figures 5 and 6, the conventional lens position detection device required three rows of conductive parts to detect exactly the same position. On the other hand, it is only necessary to provide two rows of light and dark pattern parts. As shown in FIG. 4 of this embodiment.

By arranging adjacent photosensors in positions that are not parallel to each other and separated by a difference l.

Interference of light from adjacent photosensors can be prevented, and the distance n can be shortened. Therefore, it is possible to shorten the length r of the external portion of the lens. Furthermore, since the number of component parts is small, it has a very large effect on reducing the size and weight of the lens.

On the other hand, advances in semiconductor technology have made it possible to obtain extremely small photo sensors at low cost, and light and dark patterns can be easily and inexpensively created by pasting or printing. Moreover, the number of assembly steps is small, and it is very effective in reducing the cost of lenses.

Therefore, from the above, when the lens using the lens position detection device of this embodiment is used in a video camera or a camera-integrated VTRIC, the protrusion from the outer diameter of the lens is very small, and the design is smart, small, lightweight, and It can be made low cost.

Effects of the Invention As described above, the present invention detects the position of the lens by detecting the light and dark pattern provided on the circumference of at least one of the focus ring and the zoom ring using a photo sensor fixed at a predetermined position. is carried out optically and without contact.
And because it has a small number of parts, it is small, lightweight, low cost, and durable.

A lens position detection device with excellent stability can be constructed.

Therefore, a significant effect can be obtained in reducing the size, weight, and cost of the lens and video camera or camera-integrated VTR.

[Brief explanation of drawings]

FIG. 1 is a side view of an embodiment of the present invention, FIG. 2 is a sectional view of FIG. 1 seen from the front, FIG. 3 is an enlarged view of the position detection section used in the embodiment of the present invention, The figure is a top view showing the arrangement of the photosensor in the same embodiment, Figure 5 is a sectional view of the conventional lens detection device seen from the front, and Figure 6 is a partially cutaway right side view of Figure 5. . 11...Focus ring, 12...
Zoom ring % 13-16...Photo sensor, 111L. 11b, 11C, 122L, 12b... Light and dark pattern portion, 17... P plate, 18... Fixed member, 19... Lens barrel body, 20・・・・・・
・Lens optical axis. Name of agent: Patent attorney Toshio Nakao and 1 other person
4 causes

Claims (2)

[Claims] (1) A lens barrel body, a focus ring that rotates at a predetermined angle on the outer periphery of the lens barrel body to focus on the imaging surface, a zoom ring that changes the focal length of the lens, and the focus ring; A bright and dark pattern portion provided on at least one circumference of the zoom ring, a photosensor provided at a position facing the bright and dark pattern portion, and a fixing means for fixing the photosensor at a predetermined position. A lens position detection device comprising: (2) The lens position detection device according to claim (1), wherein the at least two photosensors are arranged so as not to be located on the same line orthogonal to the optical axis of the lens.