KR100259147B1 - Linear motor for controlling automatic focus of a video camera - Google Patents

Abstract

PURPOSE: A linear motor for automatically adjusting a focus is to reduce a power consumption by linearly moving a focus lens using the linear motor having a minimum size and shape. CONSTITUTION: A barrel master(50) is coupled to a rear of a lens barrel, and is provided therein with two guide shafts in a diagonal direction. A yoke(54) is fastened to upper and lower portions of the barrel master by a screw(56), and a fixing magnet(58) is adhered to an inner side of the yoke. A focusing member is mounted onto the guide shaft and the yoke, and is linearly movable along a zoom lens. A sensor fixing plate(60) is inserted into a fixing hole(50a) formed on a side of the barrel master, and a three-phases magnetic resisting sensor(62) is integrally adhered to the sensor fixing plate to monitor a position thereof. The focusing member includes a cell bobbin(64) with a focus lens(66) adhered to a center thereof, and a driving coil for producing a magnetic field.

Description

Linear motor for automatic focusing of video camera

The present invention relates to a linear motor for automatic focus adjustment of a video camera, and more particularly, to a thin linear motor for linearly reciprocating a focus lens to have a minimum size, and to reduce mechanical load to provide a focus lens at a precise position. A linear motor for auto focusing of a video camera that can be controlled.

In general, a video camera including a camcorder or the like automatically adjusts the focus of light irradiated from a subject, records an image reaching the image pickup device on a recording medium, and has recently been widely used as a device for reproducing a recorded image. It is a trend that is widely used.

Such a video camera reaches an image pickup device through a zoom lens for zooming in or out with high magnification of light from a subject and a focus lens that is moved in the same manner, thereby forming a constant image on its surface. In this case, the focus lens is linearly reciprocated by the driving force of the stepping motor, and focuses incident light on the subject to the image pickup device. However, as the stepping motor is applied, mechanical load, that is, backlash and friction between the gears are generated, and power consumption is particularly high. In addition to the increase, the high speed movement and precise position control of the focus lens were impossible.

In order to solve this disadvantage, conventionally, as shown in FIGS. 1 to 3, a linear motor is applied to an image pickup apparatus to linearly move a focus lens for focusing incident light passing through a zoom lens. It became. In the imaging device, a barrel master 12 having a guide pin 10 fixed thereto is fastened by a plurality of fixing screws 14 to the rear of the lens barrel (not shown), and the inside of the barrel master 12. The upper and lower surfaces of the "c" shaped yoke 16 are fixed by the fixing screw 14, and the magnet 18 is attached to the inner surface of the yoke 16.

The cell bobbin 20 is inserted into the yoke 16 having a gap of about 2.5 mm with the guide pin 10 so as to be movable in a straight line. The front surface of the cell bobbin 20 is attached with a focus lens 22 for adjusting the focus of the incident light passing through the zoom lens, the outside of which is connected to the flexible substrate (FPC) 24 is exposed to the outside portion Coil 26 is wound in a rectangular shape.

And, the position magnet 28 is fixed to one side of the cell bobbin 20, the sensor fixing plate containing a three-phase magnetoresistive sensor (not shown) to correspond to the position of the position magnet 28 on one side of the barrel master 12 30 is mounted.

In the conventional autofocus adjusting linear motor configured as described above, if the video camera is not operated while the cell bobbin 20 with the fogger lens 22 is inserted into the yoke 16, the yoke 16 is inserted. The cell bobbin 20 linearly reciprocates freely inside the barrel master 12 along the guide pin 10.

Then, when power is applied to the driving coil 26 wound on the cell bobbin 20 through the flexible substrate 24 drawn out to operate the video camera, the magnetic field and the magnet generated in the driving coil 26 are applied. Due to the interaction between the cells 18, the cell bobbin 20 is magnetically floated and moves straight along the guide pin 10. That is, since the electromagnetic force generated in the driving coil 26 and the magnet 18 is stronger than the gravity according to the load of the cell bobbin 20 itself, the cell bobbin 20 maintains a linearly movable state.

At this time, the cell bobbin 20 is to focus along the zoom lens by the position signal of the feedback (feed back) associated with the three-position magnetoresistive sensor of the position magnet 28 and the sensor fixing plate 30 fixed to one side thereof In this case, the camera stops at a certain position and is ready to take an image of the subject.

However, in the conventional automatic focusing linear motor configured as described above, a lens barrel is manufactured with a diameter of 32 mm and a length of 72 mm so as to correspond to a general video camera, for example, a video camera having an appearance standard of 65 mm x 115 mm x 210 mm, In the barrel master coupled to the rear, a linear motor suitable for the size of the barrel master was installed in order to linearly move the focus lens. Therefore, there was a problem in that the outline size of the image pickup device to which the linear motor was applied could not be reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to make the thinning of the image pickup apparatus possible by making it have the minimum dimensions and the appearance of the linear motor for automatically adjusting the focus of the focus lens. To provide a linear motor for automatic focusing of a video camera.

Another object of the present invention is to move the focus lens to a reciprocating linear lens with a thin linear motor, so that the lens can be moved from low power to high speed, thereby reducing power consumption. To provide a linear motor for automatic focusing of a video camera that can accurately adjust the focus of the focus lens according to the present invention.

1 is an exploded perspective view showing a conventional automatic focusing linear motor applied to an imaging device;

2 is a cross-sectional view of the linear motor for adjusting the auto focus shown in FIG.

3 is a side view of the linear motor shown in FIG.

4 is an exploded perspective view showing a linear motor for automatic focus adjustment of a video camera according to the present invention;

5 is an assembled cross-sectional view of a linear motor for automatic focus adjustment according to the present invention,

6 is a side cross-sectional view of the linear motor shown in FIG.

* Explanation of symbols for main parts of the drawings

50: barrel master 50a: fixing hole

52: guide shaft 54: yoke

56: fixing screw 58: fixing magnet

60: sensor fixing plate 62: three-phase magnetoresistive sensor

64: cell bobbin 64a: insertion hole

66: Focus Lens 68: Self Fusion Coil

70: power supply substrate 72: flexible substrate

74: location magnet

In order to achieve the above objects, the present invention, a barrel master having a magnetoresistive sensor and a guide shaft; A yoke fixed to an inner surface of the barrel master and having a fixed magnet attached thereto; A drive coil inserted into the yoke; And a cell bobbin bonded to the driving coil to be guided to the guide shaft and having a focus lens.

Best Mode for Carrying Out the Invention A preferred embodiment of a linear motor for automatic focusing of a video camera according to the present invention will be described in detail with reference to the accompanying drawings.

4 to 6 are diagrams illustrating a linear motor for automatic focusing according to the present invention, in which two guide shafts 52 are fixed diagonally in the barrel master 50 that is coupled to the rear of the lens barrel and constitutes the imaging device. The upper and lower surfaces of the barrel master 50 are fastened to each other by a fixing screw 56 and a fixing magnet 58 is attached to the inner surface of the yoke 54. do.

Focusing means capable of linearly reciprocating along a zoom lens is inserted into the guide shaft 52 and the yoke 54 so as to focus the incident light of the subject, and the fixing hole 50a formed on one side of the barrel master 50. The sensor fixing plate 60 is fitted therein, and the three-phase magnetoresistive sensor 62 for detecting a position is integrally attached to the sensor fixing plate 60.

The focusing means includes a cell bobbin 64 having a focus lens 66 for adjusting the focus of incident light, and a driving coil for generating a magnetic field by applying power applied to one side of the cell bobbin 64. It is composed. The cell bobbin 64 is made of PPS material containing about 5% of Teflon in order to improve heat resistance. The driving coil is preferably a self-bonding coil 68 wound to form an insert portion into which the yoke 54 can be inserted when the cell bobbin 64 is bonded.

The self-fusion coil 68 is connected with a flexible substrate 72 connected to an external power supply substrate 70 to apply power thereto, and inserted into two guide shafts 52 on both sides of the cell bobbin 64. The insertion hole 64a is formed, and the position magnet 74 is fixed to one surface of the upper side in order to detect the position of the focusing means by the three-phase magnetoresistive sensor 62.

Here, each of the elements constituting the linear motor has a minimum size, thickness and diameter in order to thin the imaging device. In other words, the yoke thickness and the air gap are 1.2mm and 1.5mm, so that the self-fusion coil having a width of 0.7mm can be linearly moved, and the diameter of the focus lens is 7.9mm.

Referring to the action of the focusing linear motor according to the present invention configured as described above in detail.

Fix the yoke 54 with the fixing magnet 58 to the upper and lower inner surfaces of the barrel master 50 having a compact size and thickness, respectively with the fixing screw 56, and then attach the self-welding coil 68 to the yoke 54. ) And the cell bobbin 64 is inserted into the guide side 52 through the insertion hole 64a, whereby the coupling of the linear motor is completed. At this time, the self fusion coil 68 has a gap of 1.2 mm with respect to the yoke 54.

Thus, the cell bobbin 64 is not applied when the power supply is not applied to the imaging device configured by combining the barrel master 50 in which the linear motor is assembled to the rear of the lens barrel manufactured to have a width of 27 mm, a height of 32.5 mm, and a length of less than 53 mm. The linear reciprocating movement freely inside the barrel master 50 along the guide shaft 52.

Then, when the power supplied from the power supply substrate 70 to prevent the damage and deformation of the flexible substrate 72 having a thickness of 1mm to photograph the subject or the object is applied to the self-fusion coil 68, the fixed magnet As the magnetic flux of (58) crosses the magnetic fusion coil 68 at right angles, the cell bobbin 64 starts to operate in accordance with Fleming's left hand law.

That is, the position of the cell bobbin 64 to which the position magnet 74 is fixed is detected by the three-phase magnetoresistive sensor 62 of the sensor fixing plate 60 fitted in the fixing hole 50a of the barrel master 50, and then By the detected position signal, the cell bobbin 64 is stopped at a predetermined position according to the zoom, thereby focusing the image on the image pickup device. When the subject is moved during the photographing, the image formed on the image pickup device is shifted according to the zoom operation and the light amount of the aperture controlling the incident light amount, and thus the focus of the incident light can be adjusted within a short time as it is adjusted by the controller.

As described above, according to the linear motor for autofocus adjustment of the video camera according to the present invention, the linear lens for automatically adjusting the focus of the focus lens is manufactured to have a minimum dimension and shape, and the image pickup apparatus is made thin, thereby providing a focus lens. The linear reciprocating movement at low power and high speed reduces power consumption, and in particular, precise position control enables precise focus adjustment according to a zoom lens at any time during shooting.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

Claims (4)

A barrel master having a magnetoresistive sensor and a guide shaft; A yoke fixed to an inner surface of the barrel master and having a fixed magnet attached thereto; A drive coil inserted into the yoke; And A cell bobbin bonded to the driving coil to be guided to the guide shaft and having a focus lens; Linear motor for adjusting the focus of the video camera, characterized in that it comprises a. The linear motor of claim 1, wherein the driving coil is connected to a flexible substrate. The linear motor for adjusting a focus of a video camera according to claim 2, wherein the driving coil is a self-sealing coil. The linear motor of claim 2, wherein the flexible board is connected to a power supply board.

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