JP2008033300A - Method for adjusting image projection display device - Google Patents

Abstract

An adjustment method of an image projection display device capable of performing focus adjustment (projection distance adjustment) without moving an image projection optical unit in a vertical direction.
An adjustment method for performing focus adjustment by combining a step of moving an image projection optical unit in a direction orthogonal to a screen and a step of moving a small mirror in at least one direction orthogonal to a direction parallel to the screen.
[Selection] Figure 2

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 beam emitted from the image projection optical unit is reflected and bent, and all the light beams are incident on the screen obliquely.
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 performing focus adjustment at that time (projection distance adjustment, apart from the focus adjustment mechanism of the image projection optical unit itself), the image projection optical unit itself has to be moved vertically (vertically).

  However, since the image projection optical unit is heavy, it is mechanically difficult to move it along a direction different from the horizontal direction (direction including the vertical direction component).

  An object of the present invention is to provide an adjustment method for an image projection display device that can perform focus adjustment (projection distance adjustment) only by moving in the horizontal direction without moving the image projection optical unit in the vertical direction.

  The present invention can combine the step of moving the image projection optical unit in a direction orthogonal to the screen and the step of moving the small mirror parallel to the screen in a plane including the reference principal ray before and after reflection by the small mirror. For example, this is based on the knowledge that focus adjustment is possible even in an obliquely incident rear projection television.

  That is, the present invention includes an image projecting optical unit that projects an image; a screen; and a small mirror that reflects and bends the light emitted from the image projecting optical unit so as to enter the screen obliquely. In the projection display device, a combination of 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, The projection distance between the image projection optical unit and the screen is adjusted without changing the optical path of the reference principal ray reflected and incident on the screen. 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 both the image projection optical unit and the small mirror are moved in a direction orthogonal to the screen, both are moved in a direction orthogonal to the screen by a movement amount according to the ratio of the following formula (1) :( 2). .
(1) 1 / tan (ω + 2γ) -1 / tanω
(2) 1 / tan (ω + 2γ) + 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; and γ = 90 ° -ω-β,
It is.

In the aspect in which the image projection optical unit is moved in the direction orthogonal to the screen and the small mirror is moved in the direction orthogonal to the screen, the same parameters are used, and the ratio of Equation (1): (3) is followed. The image projection optical unit may be moved in a direction orthogonal to the screen and the small mirror may be moved in a direction parallel to the screen by the amount of movement.
(1) 1 / tan (ω + 2γ) -1 / tanω
(3) tanβ ((1 / tan (ω + 2γ) + 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 the 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 a direction parallel to or orthogonal to the screen. The focus adjustment (projection distance adjustment) during assembly can be performed.

  FIG. 1 is a conceptual diagram showing a method of adjusting focus during assembly of an obliquely incident image projection display device (rear projection television) 10. 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 moved in a direction 14Y parallel to the focus. The movement of the small mirror 14 is performed in a plane including the reference principal ray before and after reflection by the small mirror 14. By appropriately setting the ratio of the amount of movement of the image projection optical unit 13 and the small mirror 14, the position of the reference principal ray 14P reflected by the small mirror 14 is not changed (therefore, the vertical position of the image with respect to the flat screen 12). The distance between the image projection optical unit 13 and the flat screen 12 can be adjusted.

  2 and 3 are principle diagrams showing that the above adjustment is possible. 2 and 3, the solid lines of the image projection optical unit 13 and the small mirror 14 are the positions before adjustment, and the chain line is the position after adjustment. Both the image projection optical unit 13 and the small mirror 14 are moved and adjusted in directions 13X and 14X orthogonal to the flat screen 12. The image projection optical unit 13 and the small mirror 14 are present at positions where the position of the reference principal ray 14P reflected by the small mirror 14 is not changed even after the adjustment.

Now, the angle between the reference chief ray incident on the flat screen 12 and the normal line of the flat screen 12 is ω, the angle between the small mirror 14 and the normal line of the flat screen 12 is β, and the reference chief ray reflected by the small mirror 14 Is the normal to the small mirror 14 and γ (both are positive in the direction of the figure), the amount of focus shift correction (the image projection optical unit before and after the movement of the image projection optical unit 13 and the small mirror 14) (The difference in optical path length from 13 to the flat screen 12) in FIG.
Defocus correction amount = FD + AD = 1 / sinω + 1 / sin (ω + 2γ)
Given in. Note that Φ, ω, and γ are positive counterclockwise with respect to each normal. However, β is positive in the clockwise direction with respect to the normal. Arrows are attached in the positive direction of each angle shown in FIGS.
The amount of movement of the image projection optical unit 13 in the direction orthogonal to the screen 13X in order to give this amount of focus deviation correction is given by AF in FIG.
AF = AG-FG = 1 / tan (ω + 2γ) -1 / tanω
It is.
Similarly, the amount of movement of the small mirror 14 in the direction orthogonal to the screen 14X is given by AC in FIG.
AC = AG + GC = 1 / tan (ω + 2γ) + 1 / tanβ
It is.

That is,
AF: AC = 1 / tan (ω + 2γ) -1 / tanω: 1 / tan (ω + 2γ) + 1 / tanβ
The image projection optical unit 13 and the flat screen 12 are moved without changing the vertical position of the image on the flat screen 12 by moving the image projection optical unit 13 and the small mirror 14 in the direction orthogonal to the screen. And the distance 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 GD in FIG.
GD = tanβ ((1 / tan (ω + 2γ) + 1 / tanβ)
It is.

Therefore,
AF: GD = 1 / tan (ω + 2γ) -1 / tanω: tanβ ((1 / tan (ω + 2γ) + 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 distance between the image projection optical unit 13 and the flat screen 12 can be adjusted.

Next, specific examples of the focus adjustment amount 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 φ between the incident light on the flat screen 12 and the normal line of the screen 12 = 52.30 ° ω = 2.30 ° β = 38.00 ° γ = 29.70 ° Defocus correction amount = 10.00 mm
Amount of movement of the image projection optical unit 13 in the direction orthogonal to the screen 13X = −6.29 mm
Movement amount of the small mirror 14 in the direction orthogonal to the screen 14X direction = 3.91 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 projection optical unit 13 in the screen orthogonal direction 13X direction = −6.29 mm
Amount of movement of the small mirror 14 in the screen parallel direction 14Y = 3.06mm

  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 Housing | casing 12 Flat screen 13 Image projection optical unit 13X Screen orthogonal direction 14 Small mirror 14P Reference | standard principal ray 14X after reflection 14Y 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:
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 are combined and reflected by the small mirror, and the screen A method for adjusting an image projection display device, comprising: adjusting a projection distance between an image projection optical unit and a screen without changing an optical path of a reference chief ray incident on the screen. 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 in a direction orthogonal to the screen by a movement amount according to a ratio of the following expression (1) :( 2). Method for adjusting image projection display device.
(1) 1 / tan (ω + 2γ) -1 / tanω
(2) 1 / tan (ω + 2γ) + 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; and γ = 90 ° -ω-β. 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 a ratio of the following expression (1) :( 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 / tan (ω + 2γ) -1 / tanω
(3) tanβ ((1 / tan (ω + 2γ) + 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; and γ = 90 ° -ω-β.   4. The image projection display device adjusting method 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. Adjustment device for an 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 with a peripheral light beam of a wide-angle projection optical system. 6. Method.

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