JP2007079328A - Aperture driving device, lens unit, video display device - Google Patents

Abstract

【Task】
In the projection display device, the aperture ratio installed in the optical path is opened and closed to increase / decrease the contrast ratio and brightness of the displayed image and adjust the depth of the intermediate scale. Here, the yoke of the conventional aperture driving device has a thick and solid structure made of a magnetic material typified by steel using means such as die casting, cutting, or forging. Considering the reduction in size and weight of the aperture driving device, the lens unit on which the aperture driving device is mounted, and the image display device, productivity, and the like, this is not a preferable configuration.
[Solution]
An aperture that adjusts the amount of light that passes through the optical path, a coil that opens and closes the aperture, a magnet that drives the coil, and a yoke that includes a magnet and forms a closed magnetic path. The yoke is a substantially box-shaped magnetic body integrally formed.
[Selection] Figure 1

Description

  The present invention relates to an aperture driving device, a lens unit on which the aperture driving device is mounted, and an image display device.

  Japanese Patent Application Laid-Open No. 2002-23266 discloses a technique for adjusting an amount of light by inserting an aperture in an optical path of a projection display device.

  In addition, as a means to increase the contrast ratio of the display image of the projection display device, enhance the contrast of the display image, and increase the depth of the intermediate scale, the aperture is mechanically jumped into the optical path at a period synchronized with the image frame. Thus, a technique for dynamically changing the amount of light is disclosed.

JP 2002-23266 A

  In the projection display device, the aperture ratio installed in the optical path is opened and closed to increase / decrease the contrast ratio and brightness of the displayed image and adjust the depth of the intermediate scale. Here, the aperture drive device generates mechanical vibrations when the aperture is opened and closed.However, if the center of the aperture deviates from the center of the optical axis due to the influence, the aperture amount of the aperture changes and the image quality of the display image is changed. May have an impact. In order to prevent this, the housing of the aperture driving device and the magnetic material for holding the rotation shaft of the aperture are devised so as to have a thick and rigid structure.

  That is, the magnetic material 6 represented by steel shown in FIGS. 8 to 10 (hereinafter referred to as a yoke) has a thick and solid structure using means such as die casting, cutting, and forging. Is difficult.

  Further, since both ends of the rotary shaft 2 (hereinafter referred to as a pivot) of the aperture 1 are fitted and fixed to the yoke 6, a hole for receiving the shaft is required to have high dimensional accuracy, but such a structure of the yoke 6 is thick. Since it becomes heavier, it is difficult to reduce the size and weight of the apparatus. Further, it takes time and effort for the molding process, and the cost of parts increases, resulting in poor productivity.

  Furthermore, since the aperture driving device incorporated in the lens unit casing is increased in size due to the above-described rigid yoke structure, it is difficult to reduce the size of the entire lens unit.

  In order to solve the above problems, an object of the present invention is to provide an aperture driving device, a lens unit, and a video display device that can be downsized.

  In order to solve the above problems, the present invention provides an aperture for adjusting the amount of light passing through an optical path, a coil for opening and closing the aperture, a magnet for driving the coil, and a magnet inside to form a closed magnetic path. And a yoke. The yoke is a substantially box-shaped magnetic body integrally formed.

  The present invention also includes an aperture for adjusting the amount of light passing through the optical path, a coil for opening and closing the aperture, a magnet for driving the coil, and a yoke having a recess serving as a rotation axis of the aperture. The yoke is a substantially box-shaped magnetic body integrally formed.

  According to the present invention, the aperture driving device, the lens unit, and the video display device can be miniaturized.

  In the embodiment of the present invention, in order to improve the contrast of a display device such as a front projector and a rear projection TV, an aperture driving device that opens and closes so as to mechanically adjust the light amount of the projector will be described as an example.

  First, a conventional aperture driving device will be described for comparison. 8 to 10 are views showing a conventional aperture driving device, in which FIG. 8 is a front view thereof, FIG. 9 is a front perspective view thereof, and FIG. 10 is a top view thereof. FIG. 5 is a sectional view of a projection lens unit on which the aperture driving device is mounted.

  In the conventional aperture driving apparatus shown in FIGS. 8, 9, and 10, reference numeral 1 denotes an aperture that dynamically narrows the light amount of the projector. This aperture 1 is connected to an arm 3 having a pivot 2 as a rotation axis, and a voice coil 4 Are arranged symmetrically.

  The voice coil 4 is arranged in a field between a substantially fan-shaped permanent magnet 5a, half of which is N-pole and the other half is magnetized to the S-pole, and an opposing substantially sector-shaped permanent magnet 5b. The permanent magnets 5a and 5b are Attached to yokes 6a and 6b made of a magnetic material typified by carbon steel, the yokes 6a and 6b face each other to form a closed magnetic circuit.

Since the yokes 6a and 6b are generally formed by die casting, cutting, forging, or the like, each of the yokes 6a and 6b has a divided structure. Further, a hole for receiving a shaft for fitting and fixing both ends of the pivot 2 of the aperture 1 is opened. For fitting, the holes of the yokes 6a and 6b require high dimensional accuracy. The pivot 2 is the center axis of rotation of the aperture 1 and is a portion that receives vibration when the aperture is opened and closed. A rigid structure is required. In the conventional aperture driving device, the yokes 6a and 6b are thick and have a firm structure.
The aforementioned yokes 6 a and 6 b are held by a fixing screw 8 together with an interface frame 7 for attaching the aperture driving device to the projection lens unit 10.
When a current is supplied from the SERVO circuit to the voice coil 4 via a conductor, a magnetic field is generated in the voice coil 4 and acts on a field including the permanent magnets 5a and 5b and the yokes 6a and 6b, and the arm to which the aperture 1 is attached. 3 swings like a pendulum with the pivot 2 as a rotation axis. When a signal with the maximum DUTY ratio is input, the aperture 1 moves to the CLOSE position side shown in FIG. 8, and when a signal with the minimum DUTY ratio is input, the aperture 1 moves to the OPEN side at a period synchronized with the image frame. In addition, the pendulum motion is mechanically repeated within the range indicated by θ with the aperture amount converted according to the image of the image frame.

  The position of the arm 3 is always detected by the sensor 9, the position information is fed back to the SERVO circuit, the amount of current supplied to the voice coil 4 is controlled, and the amplitude position of the arm 3 is corrected with respect to the input signal.

  The aperture driving device configured as described above is mounted on the projection lens unit 10 shown in FIG. 5, and the unit is mounted on an application such as the front projector shown in FIG. 6 or the rear projection TV shown in FIG. System control is performed.

  The image processor of the optical engine calculates the aperture level for each frame by determining the brightness level of the image signal to be projected, determines the aperture amount, supplies current from the SERVO circuit to the voice coil 4 via the conductor, and the arm 3 tilts. At the same time, the aperture 1 jumps into the optical path 13 passing through the projection lens unit 10 and performs an operation of increasing the contrast ratio of the image by reducing the amount of projection light according to the amount of aperture determined above.

  By making the light amount emitted from the lamp light source 11 constant and mechanically causing the aperture to jump into the optical path 13 at a period synchronized with the image frame to dynamically change the light amount, the brightness of the displayed image is further enhanced, especially in the middle. The effect of increasing the depth of the shade of the scale is obtained.

  Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view of an aperture driving device according to the present embodiment, FIG. 2 is a front perspective view thereof, and FIG. 3 is a view showing an example of a top view thereof.

  Reference numeral 1 denotes an aperture that dynamically narrows the amount of light of the projector. The aperture 1 is arranged symmetrically with the voice coil 4 on an arm 3 made of a non-magnetic material with the pivot 2 as a rotation axis.

  The voice coil 4 is arranged in a field between a substantially fan-shaped permanent magnet 5a, half of which is N-pole and the other half is magnetized to the S-pole, and an opposing substantially sector-shaped permanent magnet 5b. The permanent magnets 5a and 5b are These are attached to the inner surface of a substantially box-shaped yoke 6 made of a magnetic material typified by a steel plate to form a closed magnetic circuit.

The structure of the yoke 6 is characterized by being integrally processed by general press molding or the like. Further, both ends of the rotation shaft of the pivot 2 which is the rotation center of the arm 3 are press-fitted into a U groove formed by press molding or the like in a part of the yoke 6, and thereafter, the tip of the U groove is caulked and fixed. Yes.
Since the yoke 6 is processed from a single steel plate by press molding or the like, it is thin and lightweight. The molding process is dramatically shortened and productivity is increased. Since it is made into a substantially box shape by integral processing, the magnetic gap of the magnetic circuit is almost zero, and the leakage flux is small and good. In the first embodiment, since the interface frame 7 for attaching to the projection lens unit 10 is also used for the yoke 6, the number of parts of the aperture driving device can be reduced and the cost can be reduced.
The yoke 6 has a thickness of about 1.4 mm to 2.0 mm with the highest productivity, and can receive vibration transmitted to the pivot 2 when the aperture is opened and closed. Further, the magnetic flux generated by the permanent magnets 5a and 5b can be efficiently transmitted into the closed magnetic path of the magnetic material, and the leakage magnetic flux can be minimized.
In the aperture driving apparatus according to the first embodiment, the yoke 6 and the interface frame 7 are used as a single unit and are attached to the projection lens unit 10 using the mounting holes of the interface frame 7.
When a current is supplied from the SERVO circuit to the voice coil 4 via a conductor, a magnetic field is generated in the voice coil 4 and acts on a field including the permanent magnets 5a and 5b and the yoke 6, and the arm 3 to which the aperture 1 is attached is It swings like a pendulum with the pivot 2 as a rotation axis. When a signal with the maximum DUTY ratio is input, the aperture 1 moves to the CLOSE position side shown in FIG. 1, and when a signal with the minimum DUTY ratio is input, the aperture 1 moves to the OPEN side at a period synchronized with the image frame. In addition, the pendulum motion is mechanically repeated within the range indicated by θ with the aperture amount converted according to the image of the image frame.

  The aperture driving device configured as described above is mounted on the projection lens unit 10 shown in FIG. 5, and the unit is mounted on an application such as the front projector shown in FIG. 6 or the rear projection TV shown in FIG. System control is performed.

  The image processor of the optical engine calculates the aperture level for each frame by determining the brightness level of the image signal to be projected, determines the aperture amount, supplies current from the SERVO circuit to the voice coil 4 via the conductor, and the arm 3 tilts. At the same time, the aperture 1 jumps into the optical path 13 passing through the projection lens unit 10 and performs an operation of increasing the contrast ratio of the image by reducing the amount of projection light according to the amount of aperture determined above.

  By making the light amount emitted from the lamp light source 11 constant and mechanically causing the aperture to jump into the optical path 13 at a period synchronized with the image frame to dynamically change the light amount, the brightness of the displayed image is further enhanced, especially in the middle. The effect of increasing the depth of the shade of the scale is obtained.

  FIG. 11 shows a projection display device on which the above-described aperture driving device is mounted. Reference numeral 10 denotes a lens unit that passes light emitted from the light source, 11 denotes a light source that emits light, 12 denotes an image element that reflects light emitted from the light source, and 13 denotes an optical path.

  The light emitted from the light source 11 is reflected by the image element 12. The image element 12 is, for example, an element provided with many micromirrors or a liquid crystal type reflection element. In the case of micromirrors, light is output for each pixel by turning the mirror on and off based on the signal input from the signal control circuit, and in the case of liquid crystal type, the transmittance is changed to output light, Each can generate a desired video.

  The light output from the image element 12 enters the lens unit 10, and an aperture driving device is installed at a position where the aperture can be inserted into the optical path in the lens unit 10. The lens unit 10 includes a lens that receives light from the light source 11 and another lens that emits light that has passed through the lens unit 10.

  The aperture drive device can adjust the contrast of the image satisfactorily by adjusting the amount of light in the optical path by opening and closing the aperture. The aperture driving device rotates the aperture by a predetermined amount so that the amount of light passing through each frame of the image signal becomes a desired amount, and inserts the aperture in the optical path so as to obtain the desired amount of light, thereby limiting the amount of light passing through. To work. This makes it possible to output an image with a suitable contrast for each frame.

  Although an example using the image element 12 that reflects light is shown here, the present invention is not limited to this, and the present invention can also be applied to devices other than the reflection type.

  FIG. 4 is a view showing an example of a top view of the aperture driving apparatus according to the second embodiment of the present invention. The difference from the first embodiment is that the yoke 6 and the interface frame 7 are divided. .

  In this example, the degree of freedom when attaching the aperture driving device to the projection lens unit 10 is increased. Depending on the structure of the lens unit housing, the structure of the interface frame 7 becomes complicated, and if the interface frame 7 and the yoke 6 are integrally processed by press molding or the like, there is a risk that the mold has a complicated and short life. In that case, by dividing the yoke 6 and the interface frame 7, the degree of freedom in designing the interface frame 7 can be increased as compared with the first embodiment, and the degree of freedom in attaching the aperture driving device can be increased.

According to the invention described in each of the embodiments described above, since the yoke is processed from a single steel plate by press molding or the like, the molding process is drastically shortened, the productivity is increased, and the thin and lightweight are used. The drive device can be reduced in size and weight.
Further, since the yoke is formed into a substantially box shape by integral processing, the magnetic gap of the magnetic circuit is almost zero, and the leakage magnetic flux can be reduced.
Also, the yoke, U-groove for press-fitting both ends of the pivot shaft, and the interface frame for attaching the aperture drive device to the projection lens unit are integrally processed by press molding, etc., thereby reducing the number of parts. However, the cost can be reduced and the assemblability can be facilitated.

  Further, it is possible to supply a projection lens unit that is equipped with a low-cost, small and light aperture drive device, can increase the contrast ratio of the projection display device, and can increase the color depth of the intermediate scale.

  In addition, supply of applications such as front projectors and rear projection TVs that are equipped with a low-cost, compact and lightweight aperture drive device, which can increase the contrast ratio of the projection display device and increase the depth of the intermediate scale hue. Is possible.

  In addition, this invention is not restricted to the structure of each Example mentioned above, A structure other than this may be sufficient.

It is a front view of the aperture drive device concerning Example 1 of the present invention. It is a front perspective view of an aperture drive device. It is a top view of an aperture drive device. It is a top view of the aperture drive device which concerns on Example 2 of this invention. It is sectional drawing of the projection lens unit carrying an aperture drive device. It is an external view of a front projector equipped with an aperture driving device. It is an external view of rear projection TV carrying an aperture drive device. It is a front view of the conventional aperture drive device. It is a front perspective view of the conventional aperture drive device. It is a top view of the conventional aperture drive device. It is a block diagram of the projection display apparatus carrying an aperture drive device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Aperture, 2 ... Pivot, 3 ... Arm, 4 ... Voice coil, 5 ... Permanent magnet, 6 ... Yoke, 7 ... Interface frame, 8 ... Fixing screw, 9 ... Sensor, 10 ... Projection lens unit, 11 ... Light source, 12: Image element, 13: Optical path.

Claims (12)

An aperture for adjusting the amount of light passing through the optical path;
A coil for opening and closing the aperture;
A magnet for driving the coil;
In an aperture drive apparatus comprising a yoke having the magnet therein and forming a closed magnetic path,
The aperture driving apparatus according to claim 1, wherein the yoke is a substantially box-shaped magnetic body integrally formed. An aperture for adjusting the amount of light passing through the optical path;
A coil for opening and closing the aperture;
A magnet for driving the coil;
In an aperture drive device comprising: a yoke having a recess serving as a rotation axis of the aperture;
The aperture driving apparatus according to claim 1, wherein the yoke is an integrally formed magnetic body. The aperture driving device according to claim 1,
The aperture driving device according to claim 1, wherein the magnet is attached to face an inner surface of a substantially box-shaped yoke to form a closed magnetic path. The aperture driving device according to claim 1 or 2,
An aperture driving apparatus according to claim 1, wherein the yoke is integrally formed by press molding. The aperture driving device according to claim 1 or 2,
The aperture drive device according to claim 1, wherein the aperture is opened and closed by rotating about a rotation axis, and both ends of the rotation axis of the aperture are press-fitted into the concave portion of the yoke. The aperture driving device according to claim 1 or 2,
The aperture is opened and closed by rotating around a rotation axis,
The aperture driving apparatus according to claim 1, wherein when the aperture is opened, the aperture is not exposed to light from an optical path. The aperture driving device according to claim 1 or 2,
The aperture is opened and closed by rotating around a rotation axis,
When the aperture is closed, the aperture is inserted into the optical path and restricts the amount of light passing therethrough. The aperture driving device according to claim 1 or 2,
The aperture driving apparatus according to claim 1, wherein the yoke is made of a magnetic material and forms a closed magnetic circuit. In the lens unit that passes the light emitted from the light source,
A first lens that receives light emitted from the light source;
A second lens that emits light that has passed through the first unit to the outside;
A lens unit comprising: the aperture driving device according to claim 1. The lens unit according to claim 9, wherein
The aperture driving device includes:
A lens unit which is disposed in an optical path between the first lens and the second lens and adjusts an amount of light passing through the optical path. A light source that emits light;
A lens unit for passing light emitted from the light source;
An image display device comprising: the aperture drive device according to claim 1, which adjusts an amount of light passing through the lens unit. 12. The video display device according to claim 11, wherein the video display device is a rear projection device or a front projection device.

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