JPH077143B2 - 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 slides on the P plate 6. As shown in FIG. 6, conductive parts 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, when the focus ring 2 rotates in the direction opposite to the arrow A about the lens optical axis 7 and the tip 4a of the contact 4 is located at the position X, the conductive portion is clear as seen in FIG. The contact 4 electrically connects the 6a and the conductive portion 6b. 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 is detected by the contact between the contact 4 and the P plate 6, and the tip 4a of the contact 4 always slides on the P plate. Therefore, in terms of durability and stability. Very problematic. 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 lens main body having a magnification changing function, and a predetermined angle rotation for changing the magnification of the lens main body. A zoom ring having a cylindrical outer peripheral portion, and a focus ring having a cylindrical outer peripheral portion having substantially the same outer shape as the zoom ring and rotating coaxially with the zoom ring for focusing. A first bright / dark pattern portion formed of a plurality of rows of light reflecting members provided on the outer peripheral portion of the focus ring, and a second portion formed of a plurality of rows of light reflecting members provided on the outer peripheral portion of the zoom ring. And a plurality of reflection type photosensors arranged so that the light emitting portion and the light receiving portion face the light reflecting member of each row of the first and second light and dark pattern portions respectively, and the plurality of reflection photosensors. Type photo sensor And a bright and dark pattern detecting means fixed to the printed circuit board of the battery pack.

Action The present invention has the above-described configuration to detect the position of the lens.
The photo sensor fixed at a predetermined position can detect the bright and dark pattern portions provided on the outer circumference of the focus ring or the zoom ring, so that it can be optically performed without contact. Therefore, detection with extremely high durability and stability is possible. Also, due to recent advances in semiconductor technology, photosensors are extremely small and low cost. On the other hand, the light and dark pattern part can be printed or pasted directly on the focus ring or zoom ring, so the number of parts is small and the number of assembling steps can be reduced. You can do it.

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,
FIG. 2 is a front view of FIG. In FIG. 1, the focus ring 11 and the zoom ring 12 are
On the outer circumference of the lens barrel body 19, the lens optical axis 20 can be rotated by a predetermined angle. Then, on each circumference, the light and dark pattern portions 11a, 11b, 11c and the light and dark pattern portion 1
2a and 12b are provided. A first photosensor 13 is provided at a position facing the light and dark pattern portions 11a and 11b, a second photosensor 14 is similarly provided for the light and dark pattern portion 11c, and a third photosensor 15 is provided for the light and dark pattern portion 12a. However, regarding the light and dark pattern portion 12b, the fourth photo sensor 16 is arranged so that the adjacent photo sensors are not arranged side by side as shown in FIG.
It is arranged on the plate 17. The P plate 17 is fixed to the fixing member 18.
Lens barrel body 19 via, for example, screws 21 and 22.
It is fixed to. Also, the photo sensor is shown in FIG.
As shown by taking the photo sensor 13 of
It is composed of 13a and a light receiving portion 13b.
The same is true for the four photo sensors 14, 15, and 16,
It is fixed to the same P plate 17.

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, the light emitting portion 13a of the photo sensor 13 fixed at a predetermined position constantly emits light. The light emitted from the light emitting portion 13a passes through the path H and reaches the position I on the outer circumference of the focus ring 11. If the reflectance at the position I on the focus ring 11 is high (for example, white), the light is reflected at the position I and enters the light receiving portion 13b through the path J, so that the light receiving portion 13b emits light of the light emitting portion 13a. Light can be detected.

On the other hand, when the reflectance at the position I is low (for example, black), the light emitted from the light emitting unit 13a is hardly reflected at the position I, and therefore the light receiving unit 13b cannot detect the light from the light emitting unit 13a. Therefore, by providing a light and dark pattern around the focus ring 11, by checking whether or not the light emitted from the light emitting unit 13a can be detected by the light receiving unit 13b,
It is possible to detect the focus state.

In FIG. 1, when the focus ring 11 is at the position S and the bright and dark pattern portions 11a, 11b, 11c are high reflectance portions, the first photosensor 13 and the second photosensor 14 detect light. be able to. The light-dark pattern portions 11a and 11b and the light-dark pattern 11c correspond to the amount of difference l between the first photo sensor 13 and the second photo sensor 14 shown in FIGS. 2 and 4 in the circumferential direction. It is provided with a shift of m.

Next, as shown in FIG. 2, the focus ring rotates in the B direction, and between the first position S and the position T, the second photo sensor 14 detects the light reflected by the light and dark pattern 11c. However, the first photo sensor 13 cannot detect light. Similarly, between the position T and the position U, neither the first photosensor 13 nor the second photosensor 14 can be detected.
At the position U, only the first photo sensor 13 can detect light. Therefore, if the position S is the closest focus position, the position U is the position of ∝, and the position T is an intermediate position between them, can the first photosensor 13 and the second photosensor 14 detect light? By investigating whether or not the focus is operated, the position of the lens can be detected. 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 bright and dark pattern portions provided around the focus ring 11 and the zoom ring 12, and the light is detected by the photo sensor, thereby optically non-contacting. Since it can be performed, it has extremely high durability and stability. Further, as apparent from comparison with the conventional example shown in FIGS. 5 and 6, it is necessary to detect exactly the same position.
In the conventional lens position detecting device, three rows of conductive portions are required, but only two rows of bright and dark portions need to be provided. 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, it is possible to shorten the length r of the appearance portion of the lens. 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 bright and dark patterns 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.

As described above, in the present embodiment, the first bright-dark pattern portion provided on the circumference of the focus ring, the second bright-dark pattern portion provided on the circumference of the zoom ring, and each bright-dark pattern portion are detected. Since the first detection means, the second detection means, and the fixing means for fixing the first detection means and the second detection means on the same circuit board are provided, the focus ring and the focus ring The position of the zoom ring can be detected, and durability and stability are extremely high. Further, since the detection means (photosensor) can be mounted on the same P plate, the assembling property is good and the number of constituent parts is small, so that there is a great effect in reducing the size and weight of the lens.

In the above embodiment, the focus ring and the zoom ring rotate on the outer circumference of the lens barrel body, but the focus ring and the zoom ring may be provided in a place other than the lens barrel body. Needless to say, the present invention also includes such cases.

EFFECTS OF THE INVENTION As described above, according to the present invention, since the positions of the focus ring and the zoom ring are detected in a non-contact manner, the reliability is high, and the detection means is mounted on the same plane, so that the assembling is good. Further, since the number of parts can be reduced, an excellent lens position detecting device can be realized at low cost. Therefore, small size such as lens and video camera,
It is extremely effective in reducing weight and cost.

[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, 13-16
...... Photo sensor, 11a, 11b, 11c, 12a, 12b ...... bright and dark pattern part, 17 ...... P plate, 18 ...... fixing member, 19 ...... lens barrel main body.

Claims (1)

[Claims] 1. A lens main body having a zooming function, a zoom ring having a cylindrical outer peripheral portion which is rotated by a predetermined angle for zooming the lens main body, and has substantially the same outer shape as the zoom ring. A focus ring having a cylindrical outer peripheral portion for rotating and focusing on the zoom ring coaxially, and a plurality of rows of light reflecting members provided on the outer peripheral portion of the focus ring. The first bright and dark pattern portion, the second bright and dark pattern portion formed of a plurality of rows of light reflecting members provided on the outer peripheral portion of the zoom ring, and the light emitting portion and the light receiving portion include the first and second bright and dark portions. A plurality of reflection type photosensors arranged so as to face the light reflecting members of each row of the pattern portion, and a bright and dark pattern detection formed by fixing all of the plurality of reflection type photosensors to the printed circuit board of the same block. Specially equipped with means Lens position detection device according to.