JPH08146344A - Projection type image display device and projecting lens assembly used for the same - Google Patents

Abstract

PURPOSE: To obtain a projection type image display device which is well corrected in focusing of respective projecting optical systems of red and blue, is high in contrast and is bright by inclining and arranging the respective optical axes of the front group and rear group of projecting lenses corresponding to red and blue and a projecting tube with each other. CONSTITUTION: The projecting lens corresponding to the blue color is composed of the front group 13'-1 composed of four elements of single lenses and the rear group composed of one element of single bowl shaped lens 13'-2. A coupler 33' is so composed that the optical axis m3 of the projecting tube 23' has a swing and tilt of an angle Δθ2 clockwise on the bases of the optical axis n3 of the single lens (rear group) 13'-2. The cylindrical axis of an outside lens barrel 4 is approximately aligned to the optical axis O3 of the front group 13'-1. The outside lens barrel 4 is so constituted that the swing and tilt of Δθ1 of the optical axis O3 are formed counterclockwise around the optical axis n3 of the single lens (rear group) 13'-2. Namely, the optical axis m3 of the projecting tube 23' affords a prescribed correction angle (Δθ1 +Δθ2 ) to the optical axis O3 of the projecting lens itself.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display device and a projection lens assembly used for the same, and more particularly, to an output image from a comparatively small display device such as a projection tube or a liquid crystal display device by means of a projection lens. The present invention relates to a projection type image display device for enlarging and projecting on a screen.

[0002]

2. Description of the Related Art A so-called projection type image display device for enlarging and projecting an image of a relatively small display device with a lens has been improved in performance year by year due to advances in optical technology, circuit technology, production technology and the like. The projection type image display apparatus, which is currently in the mainstream, uses three sets of projection optical systems for red, green and blue to obtain a color image on the screen.

An example of such a conventional projection type image display device is the technique disclosed in Japanese Patent Laid-Open No. 61-95689. FIG. 7 is a diagram showing a configuration of a conventional projection-type image display device using such three sets of projection optical systems for red, green, and blue.

In FIG. 7, reference numerals 11, 21 and 31 respectively denote a projection lens, a projection tube and a coupler for red.
Reference numerals 2, 22 and 32 are green projection lenses, projection tubes, and couplers, and reference numerals 13, 23, and 33 are blue projection lenses, projection tubes, and couplers, respectively. Also, 2
Is a screen, 11-1, 12-1, 13-1 is a front group of the projection lenses 1, 12, 13 and 11-2,
12-2 and 13-2 are rear groups of the respective projection lenses 1, 12, and 13. Each projection lens 11, 12, 13 and each projection tube 2
1, 22 and 23 are optically coupled by couplers 31, 32 and 33, respectively, and the projection lenses 11, 12, 13
The transparent liquid 1 is filled between each of the projection tubes 21, 22, and 23 to improve the contrast performance.

As shown in FIG. 7, the optical axis of the front group 12-1 of the projection lens 12 corresponding to green is arranged so as to coincide with the optical axis m ₂ of the projection tube 22 corresponding to green. The optical axes m ₁ and m ₃ of the projection tubes 21 and 23 corresponding to red and blue are arranged to be inclined by θ _{1 with} respect to the optical axis m ₂ of the projection tube 22. In addition, the projection lenses 11 and 13 for red and blue
The optical axes l ₁ and l ₃ of the front groups 11-1 and 13-1 are inclined by θ _{2 with} respect to the optical axis m ₂ of the projection tube 22 corresponding to the green color (hereinafter, this is referred to as a concentration angle). It is arranged.

At this time, assuming that the projection magnification is M and the refractive index between the projection lens and the projection tube is N, tan (θ ₁ −θ ₂ ) = (N / M) tan θ ₂ It is known that there is a relation of formula, and the projection optical system corresponding to red and blue is configured so as to maintain this relation. Here, θ ₁ −θ ₂ = Δθ is defined as the correction angle. In other words, by giving this correction angle Δθ, the focus of each of the red and blue projection optical systems for obliquely projecting is prevented from becoming unbalanced on the left and right sides of the screen 2.

As another conventional technique, each of the projection lenses corresponding to red and blue is configured such that the front group and the rear group have a common optical axis, and projection is performed on the optical axis of this projection lens. By inclining the optical axis of the tube, you can project red from diagonally.
It is also known to reduce the imbalance of the focus of each blue projection optical system on the left and right sides of the screen.

In this type of projection type image display device, when the size of the projection screen (size of the screen 2) is changed, the size of the original image projected on the projection tubes 21, 22, 23 is The projection distance (distance from the tip of the projection lens to the screen 2) L is changed without changing, and the projection magnification M is changed accordingly.

[0009]

By the way, the above equation, that is, tan (θ ₁ −θ ₂ ) = (N / M) tan θ ₂
Indicates that if the projection magnification M is changed according to the screen size (projection screen size), it is necessary to reset the correction angle Δθ = θ ₁ −θ ₂ according to the projection magnification M. . Therefore, depending on the changed screen size, it is necessary to prepare a red and blue compatible coupler that forms an appropriate correction angle Δθ and a spacer that gives the correction angle Δθ, which complicates assembly and repair work. As a result, there was a problem that the cost was high.

Further, the configuration shown in FIG. 7 has a problem that the focus of each of the red and blue projection optical systems is not corrected in a balanced manner on the left and right sides of the screen, especially in an apparatus having a small screen size. . That is, the smaller the screen size, the larger the concentration angle θ ₂ ,
As a result, it is necessary to make the correction angle Δθ = θ ₁ −θ ₂ large, that is, it is necessary to largely tilt the front group with respect to the rear group of the projection lens.
There arises a problem that aberration is increased or light is eclipsed in the lens barrel to become dark.

Therefore, the technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art. The purpose is to solve the focus (screen) of each of the red and blue projection optical systems. It is an object of the present invention to provide a bright projection type image display device in which the left and right focus) are well corrected and which has a high contrast. Further, the object of the present invention is to achieve a large commonality of parts even if the projection magnification M is changed according to the screen size (size of the projection screen).
Another object of the present invention is to provide a projection-type image display device which has an improved assembling workability and is therefore inexpensive and has less variation in performance.

[0012]

In order to achieve the above-mentioned object, the present invention arranges three projection tubes, which respectively project red, green and blue monochromatic images, in line to form three projection tubes. In a projection-type image display device provided with projection lenses respectively arranged on the front surface of a tube, each projection lens includes a rear group consisting of one single lens of substantially uniform thickness, and a projection lens having a power of at least half the power of the projection lens. It consists of a front group consisting of a plurality of single lenses including a single lens having power, and each single lens of the rear group is fixed to the front surface of each projection tube via a coupler, and the coupler and projection tube are fixed. The space surrounded by the rear group single lens is filled with a transparent liquid so that the rear group single lens and the transparent liquid have a negative power as a whole, and the front group of the projection lens is The inner lens barrel that supports and fixes multiple single lenses, and And an outer lens barrel that supports and fixes the inner lens barrel to the lens, and the projection optical system for red and blue is configured such that the optical axis of the projection tube, the optical axis of the rear group, and the optical axis of the front group are different from each other. .

[0013]

According to the above construction, since the optical axes of the front group of the projection lens, the rear group of the projection lens, and the projection tube of the projection optical system for red and blue are different from each other, The tilt of the group can be set small, and good image quality can be obtained for both focus and brightness.

Further, since the projection lenses corresponding to red and blue are provided with the outer lens barrel whose cylindrical axis is inclined with respect to the end face which is in contact with the coupler, at least the light of the rear group with respect to the optical axis of the front group. You can tilt the axis. That is, at least the tilt angle θ ₁ of the rear lens group of the projection lens is obtained with respect to the tilt angle θ ₂ of the front lens group of the projection lens described above so that the inclination of the cylindrical axis is not shifted over the entire screen. Can be formed as desired. Moreover, the projection optical system corresponding to the blue projection tube and the projection optical system corresponding to the red projection tube can be shared by using the same components except the projection tube, which are rotated by 180 degrees from each other.

Furthermore, even in a device having a different screen size, in a projection optical system for red and blue, a desired correction angle can be obtained simply by rotating the outer lens barrel by 180 ° according to the different screen size. Can be set. Therefore, even when the screen sizes are different, it is possible to largely share the components of the projection optical system.

[0016]

The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a diagram showing a main configuration of a projection-type image display device according to an embodiment of the present invention. In the figure,
2 is a screen, 11 ', 21' and 31 'are red projection lenses, projection tubes and couplers,
Reference numerals 12 ', 22', and 32 'are projection lenses, projection tubes, and couplers for green, respectively, and 13', 23 ', and 33'.
Are the projection lens, projection tube, and coupler for blue, respectively.

As shown in FIG. 1, the couplers 31 ', 32' and 33 'are provided on the front surfaces of the projection tubes 21', 22 'and 23' which project red, blue and green monochromatic images, respectively. The projection lenses 11, 12 'and 13' are attached respectively.
At this time, the optical axis of the projection lens 12 ′ for green is arranged on the optical axis m ₂ of the projection tube 22 ′ for green, and the optical axis O ₁ of the projection lens 11 ′ for red and the projection lens for blue are arranged. 1
The optical axis O _{3 of} 3 ′ is arranged with a tilt of an angle θ ₂ ′ with respect to the optical axis m ₂ of the projection tube 22 ′ corresponding to green. Hereinafter, this tilt angle is referred to as a concentrated angle. In addition, the optical axes m ₁ and m ₃ of the projection tubes 21 ′ and 23 ′ corresponding to red and blue are auxiliary angles Δθ with respect to the optical axes O ₁ and O ₃ .
Form a tilt angle θ ₁ '. And
The three optical axes O ₁ , O ₃ , and m ₂ are constructed so that they intersect each other at a point P on the outside of the screen 2.

The means for forming the correction angle Δθ will be described in detail. FIG. 2 is a cross-sectional view of essential parts showing an assembled state of the projection lens (projection lens assembly) 13 'for blue color and the projection tube 23'. The projection lens 13 'is 4
The front lens group 13'-1 is composed of a single lens element and the rear lens group is composed of a single lens element 13'-2 having a substantially uniform thickness and having a bowl shape. One side of the coupler 33 'is fixed to the front surface of the projection tube 23', and the single lens 13'-2 is fixed to the other side of the coupler 33 '. And
The closed space surrounded by the single lens (rear group) 13′-2, the projection tube 23 ′, and the coupler 33 ′ is filled with the transparent liquid 1, and the single lens 13′-2 and the transparent liquid 1 are negative as a whole. (The same applies to the red and green projection optical systems).

At this time, the optical axis n ₃ of the single lens 13'-2
Based on the above, the coupler 3 is arranged so that the optical axis m ₃ of the blue-compatible projection tube 23 ′ has a tilt of an angle Δθ _{2 in} the clockwise direction.
Make up 3 '. On the other hand, in the front group 13′-1, the inner lens barrel 3 holds and fixes all four single lenses on the common optical axis O ₃ , and the outer lens barrel 4 holds the inner lens barrel 3 with the lock screw 5. Configure. Then, the leg portion 6 of the outer lens barrel 4 is fixed to the coupler 33 ′ with a screw or a rivet 7. At this time, the cylindrical axis of the outer barrel 4 is substantially coincident with the optical axis O ₃ described above, the single lens (rear lens group) to the 13'-2 of the optical axis n _3, is the optical axis O ₃ The outer lens barrel 4 is configured so that a tilt of Δθ ₁ is formed counterclockwise.

That is, the optical axis O ₃ is the optical axis itself of the above-mentioned blue-compatible projection lens 13 ', and this optical axis O 3
Optical axis m ₃ of blue corresponding projection tube 23 'to ₃ to form a predetermined correction angle Δθ = Δθ ₁ + Δθ _2. Also, Δ
Set the correction angle Δθ so that θ ₂ > Δθ ₁ and Δθ ₁ and Δθ
It is distributed to ₂ and.

On the other hand, although the cross section of the essential part of the assembled state of the projection lens (projection lens assembly) 11 'for red and the projection tube 21' in FIG. 1 is not shown, the projection optical system for red is
180 projection optical system (front group (4 single lenses, inner lens barrel, outer lens barrel), rear group, coupler) with blue structure
Rotate and use. It should be noted that the effects intended by the present invention do not change even if the specifications of the rear lens group and the front lens group of the single lens are appropriately changed depending on whether it is red or blue.

Further, in FIG. 2, reference numeral 8 denotes a single lens which constitutes a part of the front group 13'-1 of the projection optical system corresponding to the blue color. This single lens 8 has a power of the entire projection lens system. It is made of glass that has more than half the power and has little fluctuation in refractive index due to temperature and humidity. The single lens 8 in the front group is the same in the front group of the projection optical system corresponding to red and green.

FIG. 3 shows a projection lens (projection lens assembly) 13 'and a projection tube 2 for blue, which is used for a screen size larger than that of the projection type image display apparatus shown in FIG.
It is a principal part sectional view which shows the assembly state with 3 '. This Figure 1
A blue-compatible projection optical system used for a larger screen size is the same as the blue-compatible projection optical system shown in FIG. 2 with respect to the coupler 33 ′ in which the single lens 13′-2 and the projection tube 23 ′ are connected and fixed. Front group (front group assembly; 4 single lenses,
The inner lens barrel 3 and the outer lens barrel 4) 13′-1 are rotated 180 ° and fixed. 3, single lens (rear group) with respect to the optical axis n ₃ of 13'-2, the front group 13'-
The optical axis O _{3 of} 1 (which is also the cylindrical axis of the outer lens barrel 4) has a tilt of the angle Δθ _{1 in} the clockwise direction, and the optical axis m ₃ of the projection tube 23 ′ for blue color corresponds to the optical axis n ₃ . , Clockwise angle Δθ
Holds a tilt of ₂ . Accordingly, the optical axis m ₃ in this case, blue corresponds projection tube 23 with respect to the optical axis O ₃ 'is [Delta] [theta] ₂ - [delta
There will be a tilt of θ ₁ (= Δθ; correction angle).
This will be described in more detail with reference to FIG.

FIG. 4 is an explanatory diagram of the projection optical system in the case of supporting different screen sizes. Since the red corresponding optical system and the blue corresponding optical system are symmetrical with respect to the green corresponding optical system, only the green corresponding optical system and the red corresponding optical system are shown here for simplification.

In FIG. 4, L ₀ is the projection lens 11 ',
The length of the front group of 12 ', L'-1, L'-2 is the projection distance, and the length from the tip of the projection lens 11', 12 'to the screen 2'-1, 2'-2 respectively. It represents. Further, Δl ₁ and Δl ₂ indicate the deviation (hereinafter referred to as axis deviation) between the optical axis O ₁ of the projection lens 11 ′ and the central axes of the screens 2′- ₁ , 2′-2, and w is the coupler 3.
The widths of 1'and 32 'are shown. In addition, the same components as those in FIGS. 1 to 3 are denoted by the same reference numerals.

The case where the screen 2'-1 has a diagonal size of 40 inches (screen size 40 inches) and the screen 2'-2 has a diagonal size of 44 inches (screen size 44 inches) will be described below. Table 1 shows the above screen sizes of 40 inches and 4
The optical specifications of 4 inches are shown.

[0027]

[Table 1]

Normally, when changing the screen size, the size of the original image projected on the projection tube is kept constant and the projection distance is changed. In this case, the projection distance increases in proportion to the screen size. Further, since the projection optical system corresponding to red and blue projects from an oblique direction, it is necessary to project an original image distorted into a trapezoid on each projection tube surface.
In any case, it is necessary to achieve high image quality, so in order to secure the original image of a size as large as possible, the axis deviation Δl ₁ , Δ
The projection optical system is configured by having l ₂ .

The above-mentioned concentration angle θ ₂ 'is roughly determined by the geometrical structure dimensions of these projection optical systems and can be calculated by the following formula.

Θ ₂ ′ = tan [(w−Δl ₁ ) / {(L′−1) + L ₀ }] ... Equation Using the values in Table 1, the concentration angle θ ₂ ′ is
Inch and 44 inches are 8.5 ° and 7.9 °, respectively
Becomes

On the other hand, the concentration angle θ ₂ 'and the above-mentioned tilt angle θ
₁ 'relationship with, using a projection magnification M, and a refractive index N between the projection tube and the projection _{lens, tan (θ 1' -θ 2} ') = (N / M) tanθ 2' ...... formula There is a relationship represented by the above formula. Now, with N = 1.6, the results of calculating the correction angle Δθ (= θ ₁ '−θ ₂ ') from the formula are shown in the following Table 2 together with the above-mentioned concentration angle θ ₂ '.

[0032]

[Table 2]

From the above, the tilt angle Δθ shown in FIGS.
₂ and Δθ ₁ may be configured to be 1.55 ° and 0.15 °, respectively. That is, assuming that FIG. 2 has a screen size of 40 inches and FIG. 3 has a screen size of 44 inches, in FIG. 2 Δθ = Δθ ₂ + Δθ ₁ = 1.7.
3 is Δθ = Δθ ₂ −Δθ ₁ = 1.4 ° in FIG. 3, and in the projection optical system corresponding to red and blue, the outer lens barrel 4 is simply rotated 180 ° according to different screen sizes and used. , The optimum correction angle can be obtained for each screen size. Therefore, even when the screen sizes are different, the components of the projection optical system can be shared.

FIG. 5 is a side view showing the inclination of the cylindrical axis of the outer lens barrel 4, in which O-1 is the cylindrical axis of the outer lens barrel 4, and 6 is the fixing of the outer lens barrel 4. It is a leg. Leg 6
With respect to the plane PL formed by the fixed-side end surface of
The outer lens barrel 4 is formed so that -1 is tilted by the angle Δθ ₁ .

FIG. 6 is a cross-sectional view of a main part of a projection type image display apparatus according to another embodiment of the present invention, and this embodiment is an application example to a rear projection type image display apparatus which performs rear projection. Figure 6
Shows a vertical cross section of a main part cut along the axis of the projection optical system corresponding to green. In the figure, in which the same components as those in the above embodiment are designated by the same reference numerals, Projection lens 12'-1, projection tube 22 ', and coupler 3
The projection light from the projection optical system for green, which is composed of 2 ', and the projection light from the projection optical system for red and blue (not shown) are bent on the transmissive screen 2 by bending the optical path with one mirror 9. Form an image. 15 is the projection tube 2
A circuit block 10 for lighting and driving 2'and the like is a housing for accommodating each part of the rear projection type image display device.

[0036]

As described above, according to the present invention, in the projection optical system for red and blue, the optical axes of the front group of the projection lens, the rear group of the projection lens, and the projection tube are different from each other. The tilt of the front group can be set small relative to the group, and the focus,
Good image quality can be obtained in terms of brightness.

Furthermore, even if the device has different screen sizes, a desired correction angle can be obtained only by rotating the outer lens barrel by 180 ° in accordance with the different screen sizes in the projection optical system corresponding to red and blue. Can be set. Therefore, even when the screen sizes are different, it is possible to largely share the components of the projection optical system.

In general, according to the present invention, in particular, the right and left focus of the screen are well corrected, and a bright projection type image display device with high contrast can be obtained. Further, the parts can be widely shared, and the assembling workability is improved. As a result, an inexpensive device with less performance variation can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a main configuration of a projection-type image display device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a projection optical system corresponding to blue in FIG.

FIG. 3 is a cross-sectional view of a blue projection optical system used for a screen size different from that of FIG. 1 according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining projection optical systems respectively corresponding to two types of screen sizes according to an embodiment of the present invention.

FIG. 5 is a side view of the outer lens barrel of the projection lens according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a main configuration of a rear projection type image display device according to another embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a main configuration of a projection type image display device according to a conventional technique.

[Explanation of symbols]

1 Transparent liquid 2, 2'-1, 2'-2 Screen 3 Inner lens barrel 4 Outer lens barrel 5 Lock screw 6 Outer lens barrel leg 7 Screw or rivet 8 Single lens having main power 9 Mirror 11 ', 12' , 13 'group 21 after the previous group 13'-2 projection lens of the projection lens 13'-1 projection lens ', 22', 23 'projection tube 31', 32 ', 33' couplers m _1, m _2, m ₃ Optical axis of projection tube O ₁ , O ₃ Optical axis of projection lens θ ₁ ′ Angle of tilt θ ₂ ′ Convergence angle Δθ Correction angles Δθ ₁ , Δθ ₂ Angle of tilt L′-1, L′-2 Projection distance Δl ₁ , Δl ₂ axis misalignment

Claims (4)

[Claims] 1. A projection type in which three projection tubes for respectively projecting red, green, and blue monochromatic images are arranged in an in-line form, and projection lenses are provided in front of the three projection tubes, respectively. In the image display device, each of the projection lenses includes a rear group including one single lens having a substantially uniform thickness, and a plurality of single lenses including a single lens having a power that is at least half the power of the projection lens. A front lens group, and each single lens of the rear lens group is fixed to the front surface of each projection tube through a coupler, and is surrounded by the coupler, the projection tube, and the single lens of the rear lens group. The rear lens group of the projection lens corresponding to the red and blue projection tubes is configured such that the transparent space is filled with a transparent liquid, and the single lens of the rear group and the transparent liquid have a negative power as a whole. Optical axis of the projection tube and the corresponding optical axis of the projection tube The front lens group of the projection lens includes an inner lens barrel that supports and fixes a plurality of single lenses, and an outer lens barrel that supports and fixes the inner lens barrel to the coupler. A projection type image display device characterized in that the front group of the projection lens corresponding to the blue projection tube is provided with the outer lens barrel whose cylindrical axis is inclined with respect to the end face contacting the coupler. 2. A projection type in which three projection tubes that respectively project red, green, and blue single-color images are arranged in an in-line form, and projection lenses are provided respectively in front of the three projection tubes. In the image display device, each of the projection lenses includes a rear group including one single lens having a substantially uniform thickness, and a plurality of single lenses including a single lens having a power that is at least half the power of the projection lens. A front lens group, and each single lens of the rear lens group is fixed to the front surface of each projection tube through a coupler, and is surrounded by the coupler, the projection tube, and the single lens of the rear lens group. The rear lens group of the projection lens corresponding to the red and blue projection tubes is configured such that the transparent space is filled with a transparent liquid, and the single lens of the rear group and the transparent liquid have a negative power as a whole. Optical axis of the projection tube and the corresponding optical axis of the projection tube The front lens group of the projection lens includes an inner lens barrel that supports and fixes a plurality of single lenses, and an outer lens barrel that supports and fixes the inner lens barrel to the coupler. A projection type image display device, wherein the front group of the projection lens corresponding to the blue projection tube is provided with the outer lens barrel whose cylindrical axis is inclined with respect to the optical axis of the rear group. 3. The projection optical system for red and blue according to claim 1, wherein the inclination of the optical axis of the front group with respect to the optical axis of the rear group is Δθ ₁ A projection type image display device, characterized in that the relationship of Δθ ₁ <Δθ ₂ is established, where Δθ ₂ is the inclination of the optical axis of the projection tube with respect to the axis. 4. The projection lens is composed of a rear group composed of one single lens and a front group composed of a plurality of single lenses including a single lens having a power of at least half the power of the projection lens, The front group of the projection lens includes an inner lens barrel that supports and fixes a plurality of single lenses, and an outer lens barrel that supports and fixes the inner lens barrel, and the outer lens barrel is a surface formed by a mounting end surface. A projection lens assembly used in a projection-type image display device, characterized in that a cylindrical axis is inclined with respect to.