JPS62187810A - Lens position detector - Google Patents

Abstract

PURPOSE:To perform reliable detection with high durability and high stability by detecting a light-and-dark pattern part provided to the outer periphery of a focus ring and a zoom ring by a detecting means provided at a specific position. CONSTITUTION:Two light-and-dark pattern array parts 14a and 14b and focus distance numbers 15 are arranged on the outer periphery of the focus ring 11. A black frosted paint is applied over the outer peripheral surface of the focus ring 11 and the focus distance numbers 15 and light-and-dark pattern parts 14a and 14b are provided on the same periphery and a direct silk print is made on the focus ring 11 by using white paint. Infrared rays 25a and 25b are emitted by light emitting diodes 24a of photosensors 20a and 20b all the time, and the infrared rays 25a is reflected by a white part of the light-and-dark pattern part 18a of the zoom ring 12; and its reflected light is incident on the photosensor 20a, whose phototransistor 24b detects the infrared ray 25a. Thus, the infrared rays are detected corresponding to the light-and-dark pattern to detect the position of the zoom ring 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lens position detection device for an autofocus lens that can be applied 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 rapidly popular, and as video cameras and camera-integrated VTRs have become smaller and lighter, opportunities for enjoying camera photography have also increased. When taking pictures with a camera, autofocus (hereinafter referred to as A
(referred to as F) mechanism is becoming an essential element. In order to operate the AF mechanism accurately, the states of focus, zoom, etc. must be detected, 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. 3 is a cross-sectional view showing the configuration of a conventional lens position detection device used to detect the focus state. Further, FIG. 4 is a partially cutaway side view of FIG. 3. In FIG. 3, the focus ring 2 is rotatable around the lens optical axis 7. As shown in FIG. An AH moving pin 2a is protruded from the outer circumference of the focus ring 2, and is loosely fitted into a 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 T 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. As shown in FIG. 4, conductive parts ea, eb, and θC are provided on the P plate 6 at positions facing the tips 4& of the contacts 4.

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

In FIG. 3, the focus ring 2 rotates about the lens optical axis 7 in the direction opposite to the arrow A, and the tip 4a of the contact 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 A direction and is between the X and Y positions, there is no conduction between the conductive parts 6a, eb, and ec.

Next, the conductive parts 6a and 60 are electrically connected between the Y and X positions. And, at the Z position, the conductive part 6a.

ab and ec are all conductive. Therefore, if the X position is the focus position, the Z position is the closest distance position, and the Y position is approximately halfway between beauty and closest distance, then
By checking the conduction state between the conductive parts 6a, θb, and 6c, 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 4. P board 6. Since the case 6 is located and the contact 4 rotates together with the focus ring 2 (rotation angle is approximately 1000 degrees), it is extremely large in the radial and circumferential directions and is heavy in weight. Become. Also,
The number of parts is large, precision is required, and assembly time is required, which increases 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 contact 4
Since the tip 4a of the is always sliding on the P plate, durability and
There are serious problems in terms of stability. 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 problems, the lens position detection device of the present invention includes a lens barrel body and a focus ring that rotates by a predetermined angle to focus the lens barrel body. and a display character part such as a number provided on the circumference of at least one of the zoom rings that performs magnification, and a display character part such as a number provided on the same circumference as the display character part and made of the same material as the display character part. The device includes a bright and dark pattern portion, and a detection means for detecting a bright and dark state, which is disposed at a position facing the bright and dark pattern portion.

Effect The present invention has the above-described configuration, so that the position detection of the lens can be performed by
Optical detection is possible by detecting the light and dark pattern provided on the outer periphery of the focus ring and zoom ring using a detection means provided at a predetermined position.Moreover, since the detection is non-contact, it has excellent durability and It is highly stable and enables highly reliable detection. In addition, the light and dark pattern can be constructed using the same method (for example, silk printing) as the distance numbers and other characters provided on the outer periphery of the focus ring and zoom ring, so the structure is simple, the number of parts is small, and the system is compact and compact. The lens position can be detected with light weight and low cost.

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

FIG. 1 is a side view of one embodiment of the present invention, and FIG. 2 is a front view thereof.

In FIGS. 1 and 2, the focus ring 11 and the zoom ring 12 are rotatable at predetermined angles on the outer periphery of the lens barrel body 13, respectively. focus ring 11
Two rows of bright and dark pattern parts 14a and 14b and a focus distance number 15 are arranged on the outer periphery of the lens. The outer peripheral surface of the focus ring 11 is painted matte black, and the focus distance number 15 and the light and dark pattern parts 14a and 14b are provided on the same circumference, and are directly silk-printed on the focus ring 11 using white paint. has been done. The portions of the light and dark pattern portions 14a and 14b shown in matte finish in FIG. 1 are white portions. Further, an index line 16 is provided on the lens barrel body 13.

Similar to the focus ring 11, the outer periphery of the zoom ring 12 is also treated in the same way, and a focal length number 17 and two rows of bright and dark pattern parts 18a and 18b are provided on the same circumference by white silk printing.

Furthermore, light and dark pattern parts 14a, 14b, and 18a.

Photosensors 19a and 19b are located opposite 18b.

20a and 20b are arranged and fixed by a printed circuit board 21. Also, the printed circuit board 21 has a boss 22a.
, 22b are fixed to the lens barrel body 13.

Each of the photosensors 19a and 19b is composed of a combination of an infrared light emitting diode 23a and a phototransistor 23b. The photo sensors 19b are prevented from interfering with each other, thereby preventing malfunction. Similarly, the photosensors 20a and 20b are arranged such that the light emitting diode 24a is on the inside and the phototransistor 24b is on the outside.

Next, the operation of the lens position detection device of this embodiment configured as described above when used to detect the position of the zoom ring 12 will be described. As shown in FIG. 1, infrared rays 25a and 25b are constantly emitted from the light emitting diodes 24a of the photosensors 20a and 20b, and the infrared rays 25a are reflected by the white portion of the bright and dark pattern portion 18a of the zoom ring 12.
The reflected light enters the photosensor 20a, and the photosensor 20
The infrared rays 25a can be detected by the phototransistor 24b of a.

On the other hand, since the facing surface of the photo sensor 20b is not the white part of the bright and dark pattern part but the black matte part of the zoom ring 12, the infrared rays 2sb are not reflected, and the infrared rays 2sb are not reflected by the phototransistor 24b of the photosensor 2ob.
b cannot be detected. Therefore, if a predetermined bright and dark pattern is printed on the circumference of the zoom ring 12, infrared rays can be detected corresponding to the bright and dark pattern, and the zoom ring 12
position detection becomes possible.

Detection of the position of the focus ring 11 is also exactly the same as that of the zoom ring 12, so a description thereof will be omitted here.

As described above, according to this embodiment, numbers, etc. are provided on the circumference of at least one of the focus ring, which rotates at a predetermined angle to focus the lens barrel body, and the zoom ring, which changes magnification. a display character section, a light-and-dark pattern section provided on the same circumference as the display character section and made of the same material as the display character section, and a detection means disposed at a position facing the light-dark pattern section for detecting a light-dark state. This feature allows the positions of the focus ring and zoom ring to be detected without contact, increasing durability and stability. However, since the characters and the light-dark pattern can be provided at the same time by silk printing, etc., the structure is simple, the number of parts is small, the assembly is easy, and it is highly effective in reducing size and weight.

In the above-described embodiment, the text and the bright and dark pattern are directly silk-printed, but the text and the bright and dark pattern may be provided on a separate member and attached to the focus ring and the zoom ring.

Effects of the Invention As described above, the present invention detects the positions of the focus ring and the zoom ring without contact, so it is highly reliable.Moreover, the text and the bright and dark pattern can be formed using the same processing method, so the structure is simple. It is possible to realize an excellent lens position detection device that is simple, easy to assemble, and inexpensive.

Therefore, the reliability of lenses and video cameras, etc. is improved. 2. Miniaturization.

Great effect on power saving can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side view of a lens position detection device according to an embodiment of the present invention, FIG. 2 is a front view thereof, FIG. 3 is a sectional view of a conventional lens position detection device as seen from the front, and FIG. FIG. 4 is a partially cutaway right side view of FIG. 3; 11...Focus ring, 12...
Zoom ring, 13...Lens barrel body, 14
a, 14b. 18a, 18b... Light and dark pattern portion, 15...
...Focus distance number, 17...Focal length number, 19a. 19 b + 20 a + 20 b...Photo sensor. Name of agent: Patent attorney Toshio Nakao and one other person If
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l Figure 4

Claims (1)

[Claims] A display character section such as a number provided on the circumference of at least one of a lens barrel body, a focus ring that rotates by a predetermined angle to focus the lens barrel body, and a zoom ring that changes magnification. a light-and-dark pattern portion provided on the same circumference as the display character portion and made of the same material as the display character portion; and a detection means disposed at a position facing the light-dark pattern portion for detecting a light-dark state. A lens position detection device comprising: