JP2008033301A - Method for adjusting image projection display device - Google Patents

Abstract

An adjustment method of an image projection display device capable of adjusting an image position on a screen without moving an image projection optical unit in two perpendicular directions of a vertical direction and a horizontal direction.
The image projection optical unit and the screen are combined with a step of moving the image projection optical unit in a direction orthogonal to the screen and a step of moving the small mirror in at least one direction orthogonal to the direction parallel to the screen. Adjustment method to adjust the image position on the screen without changing the projection distance (optical path length) between
[Selection] Figure 3

Description

  The present invention relates to an image projection display device (rear projection television), and more particularly to an adjustment method for adjusting the state of an image on a screen during assembly.

An image projection display device (rear projection television) projects a light beam emitted from an image projection optical unit onto a screen and observes it as an image. In this image projection display device, in order to reduce the size and thickness, the light emitted from the image projection optical unit is reflected and bent, and is incident obliquely on the screen.
JP 2005-43681 A

  In this oblique projection type image projection display device, the optical axis of the image projection optical unit (more precisely, the principal ray of the light beam toward the center of the screen, hereinafter referred to as “reference principal ray”) is not orthogonal to the screen. When adjusting the vertical (vertical) position of the image on the screen at the time, the image projection optical unit itself is horizontally moved in the direction perpendicular to the screen, and the image projection optical unit and the screen are moved along with the horizontal movement. In order to correct the projection distance (optical path length) change (focus movement), it was necessary to move up and down (vertically) in the direction parallel to the screen. That is, as shown in the preceding example, when a compact structure is prioritized and the mirror is folded back at an angle, a movement in which the horizontal movement and the vertical movement are linked is necessary.

  However, since the image projection optical unit is heavy, it is mechanically difficult to move in the vertical direction (vertical direction). Especially, the movement while coordinating with the back and forth movement may cause errors. There is even sex. In addition, since other adjustments (for example, focus adjustment (projection distance adjustment)) are necessary, conventionally, the image projection optical unit must be supported so as to be movable in two horizontal and vertical orthogonal axes.

  The present invention adjusts the image position on the screen without moving the image projection optical unit in the vertical direction (vertical direction) and without changing the projection distance (optical path length) between the image projection optical unit and the screen. It is an object of the present invention to obtain an adjustment method of an image projection display device capable of (up / down position adjustment).

  The present invention provides an oblique projection rear projection by combining the step of moving the image projection optical unit in a direction orthogonal to the screen and the step of moving the small mirror in at least one direction orthogonal to the direction parallel to the screen. Also for television, based on the knowledge that image position adjustment on the screen is possible without changing the projection distance (optical path length, ie, focus state) between the image projection optical unit and the screen. It is.

  That is, the present invention provides an image projection optical unit including an image projection optical unit that projects an image, a screen, and a small mirror that reflects and bends a light beam emitted from the image projection optical unit and makes it incident obliquely on the screen. In the display device, the step of moving the image projection optical unit in a direction orthogonal to the screen and the step of moving the small mirror in at least one of the directions orthogonal to the direction parallel to the screen are combined, and the image projection optical unit and the screen are combined. The position of the image on the screen is adjusted without changing the projection distance (optical path length). The small mirror is moved in a plane including the reference principal ray before and after reflection by the small mirror. Further, if the mirror surface of the small mirror is sufficiently large, even if the small mirror is moved in the non-orthogonal direction (non-parallel direction) with respect to the screen, the moving component is substantially included in the orthogonal direction (parallel direction).

The amount of movement adjustment in the direction perpendicular to the screen of the image projection optical unit and the amount of movement adjustment in the direction parallel to or perpendicular to the screen of the small mirror can be determined by trial and error. The relationship between the quantities is as follows. In an aspect in which the image projection optical unit and the small mirror are both moved in a direction orthogonal to the screen, the image projection optical unit and the small mirror are moved to the screen by a movement amount according to the ratio of the following formula (1): (2). Move in the orthogonal direction.
(1) (1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω-1 / tanω
(2) (1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω + 1 / tanβ
However,
β (°): Angle between small mirror and screen normal,
ω (°): angle formed by the reference principal ray and the screen normal before exiting the image projection optical unit and reaching the small mirror,
φ (°): Angle between the screen normal and the reference principal ray immediately before the light beam emitted from the image projection optical unit reaches the screen,
γ = 90 ° -ω-β,
θ = 90 ° -ω-2β + φ,
It is.

In the aspect in which the image projection optical unit is moved in the direction perpendicular to the screen and the small mirror is moved in the direction perpendicular to the screen, the same parameters are used, and the ratio of the following formula (1): (3) is used. The image projection optical unit is moved in a direction orthogonal to the screen and the small mirror is moved in a direction parallel to the screen by the amount of movement accordingly.
(1) (1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω-1 / tanω
(3) tanβ [(1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω + 1 / tanβ]

  In order to reduce the thickness of the apparatus, it is preferable to provide a fixed mirror between the small mirror and the screen to give reflected light from the small mirror to the screen.

  Similarly, it is practical that the image projecting optical unit is an oblique projecting optical unit for projecting with a peripheral light beam of the wide angle projection optical system in order to reduce the thickness of the apparatus.

  According to the present invention, in an obliquely incident image projection display device, the image projection optical unit is moved by an appropriate amount in a direction orthogonal to the screen, and the small mirror is moved by an appropriate amount in at least one of the directions orthogonal to the direction parallel to the screen. By doing so, it is possible to adjust the image position on the screen at the time of assembly without changing the projection distance (optical path length) between the image projection optical unit and the screen.

FIG. 1 is a conceptual diagram showing a method of adjusting the image position on the screen during assembly of the obliquely incident image projection display device (rear projection television) 10 according to the present invention. The image projection display device 10 has a flat screen 12 on one surface of a housing 11, and an image projection optical unit (image engine) 13, a small mirror 14, and a fixed mirror 15 in the housing 11. The image light beam (light beam) emitted from the image projection optical unit 13 is reflected and bent by the small mirror 14, then enters the fixed mirror 15, and the light beam further reflected and bent by the fixed mirror 15 is converted into a flat screen. 12 is incident obliquely. A plurality of mirrors may be interposed between the image projection optical unit 13 and the flat screen 12, but the image light beam from the image projection optical unit 13 is oblique to the flat screen 12 (from a direction other than the orthogonal direction). It is essential to enter. The small mirror 14 is the mirror closest to the image projection optical unit 13.

In the image projection display device 10 described above, in the present embodiment, the image projection optical unit 13 is moved in the direction 13X orthogonal to the flat screen 12, and the small mirror 14 is moved in the direction 14X orthogonal to the flat screen 12 or the flat screen 12. Is adjusted in the vertical direction of the image on the screen 12. The small mirror 14 is moved so that the reflection surface of the small mirror 14 is parallel before and after the movement. The movement amounts of the image projecting optical unit 13 and the small mirror 14 are the optical path length before and after the adjustment from the image projecting optical unit 13 to the small mirror 14, respectively, a and a ′, and the small mirror 14 and the fixed mirror, respectively. If the optical path length before adjustment and the optical path length after adjustment up to 15 are b and b ′, respectively, and the optical path length before adjustment from the fixed mirror 15 to the flat screen 12 and the optical path length after adjustment are c and c ′, respectively, adjustment is performed. Before and after
a + b + c = a ′ + b ′ + c ′
The movement amount (ratio) is set so that is maintained. By setting the amount of movement in this manner, the vertical position of the image on the flat screen 12 (the upper and lower positions of the reference principal ray with respect to the flat screen 12 is changed without changing the optical path length from the image projection optical unit 13 to the flat screen 12. Position) can be adjusted.

  2 and 3 are principle diagrams showing that the above adjustment is possible. In FIG. 2, the solid line of the image projection optical unit 13 and the small mirror 14 is a position before adjustment, and the chain line is a position after adjustment. In FIG. 2, a normal CD of the fixed mirror 15 is set at the center of the optical path before and after adjustment, and a point B is determined at a position symmetrical with the intersection A of the mirror 15 and the screen 12 with respect to this normal CD. The optical path (solid line) length before adjustment in ΔABD is equal to the optical path (chain line) length after adjustment. Similarly, if a parallel line B′D ′ parallel to the line segment BD is drawn, the optical path length before and after the adjustment from the screen 12 to the line segment B′D ′ is equal.

  FIG. 3 is an enlarged view when the line segment B′D ′ is set to pass through the incident position E to the small mirror 14 before adjustment. From the discussion of FIG. 2, the adjusted optical path length from the screen 12 to the point D ′ (chain line) is equal to the optical path length from the screen 12 to the point E (solid line). However, since the adjusted optical path is reflected by the small mirror 14 (point I), the adjusted optical path length is actually shortened by the line segment ID '. Considering the optical path length from the image projection optical unit 13 to the small mirror 14, the optical path length before adjustment is the length of the line segment OE, whereas the optical path length after adjustment is the length of the line segment PI. It is. Since line segment PI = line segment OE + line segment JI, when ID ′ = IJ, the optical path lengths are equal before and after adjustment.

Now, β (ＨGHI, °); the angle between the normal of the small mirror 14- and the screen 12,
ω (∠PJE, °); angle formed between the light beam emitted from the image projection optical unit 13 and the normal line of the screen 12;
φ (°); the angle between the normal of the screen 12 and the light incident on the screen 12;
γ (∠KIJ, °) = 90 ° -ω-β,
θ (∠ED'Q, °) = 90 ° -ω-2β + φ,
And the length of the auxiliary line LI is 1,
Length of line segment JI = 1 / sinω
From ID '= JI,
Length of line segment ID '= 1 / sinω
Length of line segment IN = sin (ω + 2γ) / sinω
Length of line segment LN = 1 + sin (ω + 2γ) / sinω
Length of line segment ND ′ = cos (ω + 2γ) / sinω
Length of line segment ED '= (1 + sin (ω + 2γ) / sinω) / sinθ
Length of line segment QD '= (1 + sin (ω + 2γ) / sinω) / tanθ
Length of line segment LH = 1 / tanβ
Length of line segment JL = 1 / tanω
Length of line segment GL = 1 / tan (ω + 2γ)
It is.

In order to realize the above ID ′ = IJ,
The amount of movement EJ of the image projection optical unit 13 in the screen orthogonal direction 13X is
EJ = QD'-JL-ND = (1 + sin (ω + 2γ) / sinω) / tanθ-1 / tanω-cos (ω + 2γ) / sinω
age,
The amount of movement EH of the small mirror 14 in the screen orthogonal direction 14X is
EH = QD'-ND '+ LH = (1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω + 1 / tanβ
And it is sufficient.
The image vertical position adjustment amount on the screen 12 adjusted by the movement of the image projection optical unit 13 and the small mirror 14 is as follows.
ED '= (1 + sin (ω + 2γ) / sinω) / sinθ
It is.

That is,
EJ: EH = (1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω-1 / tanω: (1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω + 1 / tanβ
By satisfying the above relationship, the image projection optical unit 13 and the small mirror 14 are moved in the direction orthogonal to the screen, so that the optical path length between the image projection optical unit 13 and the flat screen 12 is not changed. The vertical position of the image can be adjusted.

Instead of moving the small mirror 14 in the screen orthogonal direction 14X, the small mirror 14 may be moved in the screen parallel direction 14Y. That is, moving the small mirror 14 by the unit movement amount “1” in the direction orthogonal to the screen is equivalent to moving “1 / tanβ” in the screen parallel direction. Therefore, the amount of movement of the small mirror 14 in the screen parallel direction 14Y direction is given by the line segment EZ in FIG.
EZ = tanβ EH = tanβ [(1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω + 1 / tanβ]
It is.

Therefore,
EJ: EZ = (1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω-1 / tanω: tanβ [(1 + sin (ω + 2γ) / sinω) / tanθ-cos (Ω + 2γ) / sinω + 1 / tanβ]
The image projection optical unit 13 is moved in the screen orthogonal direction 13X and the small mirror 14 is moved in the screen parallel direction 14Y without changing the vertical position of the image on the flat screen 12. The optical path length between the image projection optical unit 13 and the flat screen 12 can be adjusted.

Next, specific examples of the image position adjustment amount on the screen and the movement amounts of the image projection optical unit 13 and the small mirror 14 will be described. The amount of movement in the direction perpendicular to the screen is + for the direction approaching the screen 12, and the amount of movement in the direction parallel to the screen is + for downward.
Example 1
Angle between reference chief ray incident on flat screen 12 and normal of same screen 12 φ = 52.30 ° ω = 2.30 ° β = 38.00 ° γ = 29.70 ° Image vertical position adjustment on screen = 10.00mm
Amount of movement of the image projection optical unit 13 in the direction orthogonal to the screen 13X = 1.77 mm
Amount of movement of the small mirror 14 in the direction perpendicular to the screen 14X direction = 8.93 mm

Example 2
Under the same conditions, when the moving direction of the small mirror 14 is the screen parallel direction 14Y, the moving amount of the image projecting optical unit 13 in the screen orthogonal direction 13X direction = 1.77 mm.
Movement amount of small mirror 14 in the screen parallel direction 14Y direction = 6.97mm

  As a specific mechanism for moving the image projection optical unit 13 and the small mirror 14, a known linear movement mechanism can be used. For example, by using a feed screw mechanism and controlling the rotation angle of the feed screw, both can be moved at the above ratio.

It is a conceptual diagram of the adjustment method of the image projection display apparatus by this invention. It is a figure which shows the principle of the adjustment method by this invention. It is the elements on larger scale which show the principle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image projection display apparatus 11 Case 12 Flat screen 13 Image projection optical unit 13X Screen orthogonal direction 14 Small mirror 14X Screen orthogonal direction 14Y Screen parallel direction 15 Fixed mirror

Claims (5)

An image projection optical unit for projecting an image;
With a screen;
A small mirror that reflects and bends the light beam emitted from the image projection optical unit and makes it incident obliquely on the screen;
In an image projection display device comprising:
Combining the step of moving the image projection optical unit in a direction perpendicular to the screen and the step of moving the small mirror in at least one direction perpendicular to the direction parallel to the screen; A method for adjusting an image projection display device, wherein the position of an image on the screen is adjusted without changing the projection distance between the two. In the adjustment method of the image projection display apparatus of Claim 1,
An adjustment method of an image projection display device in which the image projection optical unit and the small mirror are moved in a direction orthogonal to the screen by a movement amount according to the ratio of the following equation (1): (2).
(1) (1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω-1 / tanω
(2) (1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω + 1 / tanβ
However,
β (°): Angle between small mirror and screen normal,
ω (°): angle formed by the reference principal ray and the screen normal before exiting the image projection optical unit and reaching the small mirror,
φ (°): Angle between the screen normal and the reference principal ray immediately before the light beam emitted from the image projection optical unit reaches the screen,
γ = 90 ° -ω-β,
θ = 90 ° -ω-2β + φ. 2. The adjustment method for an image projection display device according to claim 1, wherein the image projection optical unit and the small mirror are moved to the screen by an amount of movement according to the ratio of the following formulas (1) and (3). An adjustment method of an image projection display device in which a small mirror is moved in a direction parallel to the screen in a direction orthogonal to the screen.
(1) (1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω-1 / tanω
(3) tanβ [(1 + sin (ω + 2γ) / sinω) / tanθ-cos (ω + 2γ) / sinω + 1 / tanβ]
However,
β (°): Angle between small mirror and screen normal,
ω (°): angle formed by the reference principal ray and the screen normal before exiting the image projection optical unit and reaching the small mirror,
φ (°): Angle between the screen normal and the reference principal ray immediately before the light beam emitted from the image projection optical unit reaches the screen,
γ = 90 ° -ω-β,
θ = 90 ° -ω-2β + φ. 4. The adjustment method for an image projection display device according to claim 1, further comprising a fixed mirror between the small mirror and the screen for providing reflected light from the small mirror to the screen. Adjusting device for image projection display device. 5. The adjustment method of an image projection display device according to claim 1, wherein the image projection optical unit is an oblique projection optical unit that projects by a peripheral light beam of a wide angle projection optical system. Method.

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