JPH083572B2 - Lens position detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens position detection device for an autofocus lens applicable to a video camera or a camera-integrated video tape recorder (hereinafter referred to as a camera-integrated VTR).

2. Description of the Related Art In recent years, video tape recorders (hereinafter referred to as VTRs) have become remarkably widespread, and the number of opportunities to enjoy camera photography has increased due to the reduction in size and weight of video cameras or camera-integrated VTRs. When taking pictures with a camera, an autofocus (hereinafter referred to as AF) mechanism is becoming an indispensable element because it can be taken easily and surely. In order to operate the AF mechanism accurately, it is necessary to detect the states of focus, zoom, etc. Therefore, a lens position detection device is required.

Hereinafter, an example of a conventional lens position detection device will be described with reference to the drawings.

FIG. 5 is a sectional view showing the structure of a conventional lens position detecting device used for detecting the focus state. 6 is a partially cutaway side view of FIG. In FIG. 5, the focus ring 2 is rotatable around the lens optical axis 7. A drive pin 2a is provided on the outer periphery of the focus ring 2, and a slider 3 having a contact 4 fixed thereto is provided.
It is loosely fitted in the groove 3a. In addition, the lens position detection device 1
Circular guide grooves 5a centered on the lens optical axis 7 on both sides of the
Is provided, and the slider 3 is loosely fitted in this guide groove and is rotatable around the lens optical axis 7. 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 plate) 6 held inside the case 5. Therefore, when the focus ring 2 is rotated around the lens optical axis 7, the tip 4a of the contact 4 clears the P plate 6. As shown in FIG. 6, conductive portions 6a, 6b, 6c are provided on the P plate 6 at positions facing the tip 4a of the contact 4.

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

In FIG. 5, the focus ring 2 is the lens optical axis 7
Rotate in the opposite direction of arrow A around
Is in the X position, the conductive portion 6a and the conductive portion 6b are brought into conduction by the contact 4, as is apparent from FIG. Similarly, when the tip 4a of the contact 4 rotates in the A direction and is between the X and Y positions, there is no conduction between the conductive portions 6a, 6b, 6c.

Next, the conductive portions 6a and 6c are electrically connected between the positions Y and X. At the Z position, the conductive portions 6a, 6b, 6c are all in conduction. Therefore, if the X position is the focus ∝ position, the Z position is the closest distance position, and the Y position is almost the middle position between ∝ and the closest distance, the conduction between the conductive parts 6a, 6b, 6c is determined. If the state is checked, the position of the lens when the focus is operated can be detected. The same 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, the contact 4, the P plate 6, and the case 5 are located in the radial direction, and the contact 4 rotates together with the focus ring 2. Since the rotation angle is about 100 °, it is very large in the radial direction and the circumferential direction, and becomes heavy in weight. In addition, since the number of parts is large and accuracy is required, and the number of assembling steps is required, the cost is increased. Therefore, it is a serious obstacle to the recent reduction in size and weight and cost of a video camera or a VTR with a built-in camera. Further, in the above configuration, the position detection is performed by the contact 4
And the P plate 6 are in contact with each other, and the tip 4a of the contact 4 always slides on the P plate, so that there is a great problem in terms of durability and stability. Elements such as durability and stability are extremely important for video cameras and camera-integrated VTRs that are often used continuously for a long time.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and an object of the present invention is to provide a lens position detection device that is compact, lightweight, low-cost, and highly durable and stable.

Means for Solving the Problems In order to solve the above problems, a lens position detecting device of the present invention comprises a rotating ring which rotates by a predetermined angle for moving a lens, and an intermittent connection on the outer periphery of the rotating ring. Specifically provided first infrared reflecting means, second infrared reflecting means juxtaposed with the first infrared reflecting means, and infrared emitting section and infrared ray arranged opposite to the first infrared reflecting means. The first reflection type infrared sensor composed of a light receiving part and the second reflection type infrared sensor facing the second infrared reflection means are arranged at a predetermined distance in the circumferential direction of the rotating ring. And a second reflective infrared sensor provided.

Effect of the Invention According to the present invention, the position of the lens can be optically detected in a non-contact manner by detecting the reflected light from the infrared reflecting means provided on the outer circumference of the focus ring or zoom ring by the infrared receiving means. . Therefore, detection with extremely high durability and stability is possible. Further, the infrared light receiving and emitting means can use a semiconductor, the shape is very small, and it can be constructed at low cost.

In addition, since the infrared reflection means can be printed or pasted with a reflective material directly on the focus ring or zoom ring, the number of parts can be reduced and the number of assembling steps can be reduced. It will be possible to detect.

Example Hereinafter, a lens position detecting device according to an example 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, and FIG. 2 is a view of FIG. 1 seen from the front. First
In the figure, the black-painted focus ring 11 and zoom ring 12 are each rotatable on the outer circumference of the lens barrel body 19 about the lens optical axis 20 by a predetermined angle.
Further, the infrared reflecting portions 11a, 11b, 11c and the infrared reflecting portions 12a, 12b, which are printed with white paint, are arranged on the respective circumferences. A first photosensor 13 is provided at a position facing the infrared reflecting portions 11a and 11b, a second photosensor 14 is similarly provided for the infrared reflecting portion 11c, and a third photosensor is provided for the infrared reflecting portion 12a. As for the infrared reflecting portion 12b, the fourth photosensor 16 is arranged on the P plate 17 so that the adjacent photosensors are not juxtaposed on the same line orthogonal to the lens optical axis as shown in FIG. Has been done. The P plate 17 is fixed to the lens barrel main body 19 with screws 21 and 22 via a fixing member 18. The photo sensor is the first photo sensor in FIG.
As shown in FIG. 13 as an example, it is composed of an infrared light emitting portion 13a using an infrared light emitting diode and an infrared light receiving portion 13b using an infrared phototransistor, and this configuration is the second, third and fourth photosensors 14 The same is true for 15,15 and 16.

The operation of the lens position detecting device of the present embodiment configured as described above will be described below with reference to FIGS. 1 to 4, taking as an example the case where the lens position detecting device is used for detecting the focus state. . As shown in FIG. 3, infrared light is constantly emitted from the infrared light emitting portion 13a of the photo sensor 13 fixed at a predetermined position. The infrared light emitted from the infrared light emitting portion 13a passes through the path H and reaches the position I on the outer circumference of the focus ring 11. When the position I on the focus ring 11 is white, infrared light is reflected at the position I and passes through the path J to enter the infrared light receiving portion 13b. Therefore, the infrared light receiving portion 13b reflects the reflected light from the infrared light emitting portion 13a. Can be detected.

On the other hand, if the position I is black, the infrared light emitting unit 13a
Since the infrared light emitted from is hardly reflected at the position I,
The infrared light receiving portion 13b cannot detect the reflected light of the infrared light emitting portion 13a. Therefore, if the infrared reflecting portion is intermittently provided around the focus ring 11, it is possible to determine the focus state by checking whether the infrared light receiving portion 13b can detect the infrared light emitted from the infrared light emitting portion 13a. It is possible to detect.

In FIG. 1, when the focus ring 11 is at the position S, the infrared reflecting portions 11a, 11b, 11c are portions having high reflectance, and the first photosensor 13 and the second photosensor 14 detect reflected light. can do. In addition, the infrared reflection part 11
The a and 11b and the infrared reflecting portion 11c are displaced by m in the circumferential direction by an amount corresponding to the amount of difference 1 between the first photo sensor 13 and the second photo sensor 14 shown in FIGS. 2 and 4. Is provided.

Next, as shown in FIG. 2, the focus ring rotates in the B direction, and between the position S and the position T in FIG. 1, the second photosensor 14 detects the infrared rays reflected by the infrared reflecting portion 11c. First photo sensor 13 that can detect light
Cannot detect reflected light. Similarly, between the position T and the position U, neither the first photosensor 13 nor the second photosensor 14 can be detected. Then, at the position U, only the first photosensor 13 can detect the linear light. Therefore, position S is the closest focus position, position U is the position of ∝, and position T is
Is approximately halfway between the two, it is possible to detect the position of the lens when the focus is operated by checking whether the first photosensor 13 and the second photosensor 14 can detect reflected light. it can. The same method can be used to detect the position of the lens when the zoom is operated.

As described above, in the present embodiment, the position detection of the lens uses the infrared reflection portion provided around the focus ring 11 and the zoom ring 12, and the reflected light is detected by the photo sensor, thereby optically non-contacting. It is extremely durable and stable. Further, as is clear from comparison with the conventional example shown in FIGS. 5 and 6, in order to detect the exact same position, the conventional lens position detection device requires three rows of conductive parts. On the other hand, it is only necessary to provide two rows of infrared ray reflecting portions. Then, as shown in FIG. 4 of the present embodiment, the adjacent photosensors are arranged apart from each other by a difference amount 1 which is difficult to position so that light interference from the adjacent photosensors is prevented. Therefore, the interval n can be shortened. Therefore, the length r of the appearance part of the lens
Can be shortened. In addition, since the number of constituent parts is small, it is very effective in reducing the size and weight of the lens.

On the other hand, due to advances in semiconductor technology, very small photosensors can be obtained at low cost, and the infrared reflection part can be easily and inexpensively provided by pasting or printing. Moreover, the number of assembling steps is small, and it is very effective in reducing the cost of the lens.

Therefore, from the above, when the lens using the lens position detecting device according to the present embodiment is used in a video camera or a camera-integrated VTR, the protruding portion from the lens outer diameter is very small, and the design is smart, compact and lightweight. And it can be made at low cost.

EFFECTS OF THE INVENTION As described above, according to the present invention, the position of a lens is optically contact-free using infrared rays and the number of parts is small. An excellent lens position detecting device can be configured. Further, since the first and second reflective infrared sensors are arranged at a predetermined distance in the circumferential direction of the rotary ring of the lens, light from adjacent sensors does not interfere with each other. The mounting pitch between them can be shortened, the width of the rotating ring provided with the infrared reflecting means can be narrowed, and the size can be reduced while satisfying the detection performance. Therefore, a very large effect can be obtained in reducing the size and weight and the cost of the lens and the video camera or the camera-integrated VTR.

[Brief description 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, and FIG. 3 is an enlarged view of a position detector used in the embodiment of the present invention. FIG. 5 is a top view showing the arrangement of the photosensors in the same embodiment, FIG. 5 is a sectional view of the conventional lens detecting device seen from the front, and FIG. 6 is a partially cutaway right side view of FIG. . 11 …… Focus ring, 12 …… Zoom ring, 13a…
… Infrared ray emitting section, 13b …… Infrared ray receiving section, 13 to 16 …… Photo sensor, 11a, 11b, 11c, 12a, 12b …… Infrared reflecting section, 1
7 …… P plate, 18 …… Fixing member, 19 …… Lens barrel body, 2
0: Lens optical axis.

Claims (1)

[Claims] 1. A rotating ring for rotating a predetermined angle for moving a lens, a first infrared reflecting means intermittently provided on the outer periphery of the rotating ring, and the first infrared reflecting means. Second infrared reflection means arranged in parallel, a first reflection type infrared sensor which is arranged opposite to the first infrared reflection means and includes an infrared emission part and an infrared reception part, and the second infrared reflection part. A lens position facing the first reflection type infrared sensor and a second reflection type infrared sensor disposed apart from the first reflection type infrared sensor by a predetermined distance in the circumferential direction of the rotating ring. Detection device.