JPH10319290A - Projection lens device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the misalignment of the optical axes of respective lenses constituting a projection lens system and to obtain a projected image having high quality by integrally forming at least one lens out of the lenses constituting the projection lens system with a lens barrel. SOLUTION: The projection lens system 2 is constituted of plural single lenses L1 to L4 in order from a front side and disposed in the lens barrel 4. The lenses L1 to L3 out of the lenses L1 to L4 constituting the projection lens system 2 are respectively held and fixed at specified positions inside an internal lens barrel 6. The lens barrel 6 is internally fit in a lens barrel part 9 positioned on the front side of an external lens barrel 5 integrally formed with the lens L4. Namely, the external lens barrel 5 of the lens barrel 4 and the lens L4 positioned nearest to a cathode ray tube 3 side are integrally formed. Therefore, positional relation between the external lens barrel 5 and the lens L4 is always constant and the optical axes of the lens L4 and, other lenses L1 to L3 fixed in the internal lens barrel are aligned just by focusing the projection lens system 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection lens apparatus mainly used in a projection television or the like, which eliminates errors in assembling components and improves the accuracy to obtain a high quality projected image. Things.

[0002]

2. Description of the Related Art In recent years, a so-called projection television in which an image displayed on an image display device such as a cathode ray tube is enlarged and projected on a screen by a projection lens system disposed in front of an image display surface of the image display device. Is
The projection lens system and the image display device are connected by a coupler, and a liquid having high transparency and a refractive index of about 1.43 is sealed in a space formed by the projection lens system, the image display device, and the coupler. Thus, by filling the liquid between the projection lens system and the image display device,
Unnecessary reflected light generated at the interface between the image display device and the projection lens can be reduced as much as possible, and the heat radiation of the image display device can be efficiently performed.

As described above, a method of connecting a projection lens system and an image display device via a coupler and filling a liquid in a space formed by the lens, the image display device, and the coupler generally includes: It is called the optical coupling method and has greatly contributed to the improvement of the image quality of projection televisions.

FIG. 5 shows an example a of a conventional projection lens device for a projection television. The projection lens device a has a projection lens system b, and one end is connected to a cathode ray tube c.

[0005] The projection lens system b is composed of a plurality of single lenses L1, L2, L3 and L4 arranged in a lens barrel d.

The lens barrel d is connected to an external barrel e.
Lens L1, L2, and L3, except for the lens L4 closest to the cathode ray tube c, of the lenses L1 to L4 that constitute the projection lens system b, e are fixed at predetermined positions in an internal lens barrel f that is rotatably and slidably disposed in e. The lens L4 has a flange integrally formed at the front end, and the lens L4
Is attached to a coupler g connecting the lens barrel d and the cathode ray tube c.

The coupler g has both ends adhered to the cathode ray tube c and the lens L4 with a sealing rubber interposed therebetween, and a lens holding plate h and a CRT holding plate i are attached to the lens L4 and the cathode ray tube c, respectively. These and coupler g
Are fixed by screwing, and the lens L4 and the cathode ray tube c are connected. The liquid j is injected into the space formed by the cathode ray tube c, the lens L4, and the coupler g by an appropriate method.

Further, after the outer lens barrel e is fixed on the lens holding plate h by screws or the like,
The inner lens barrel f is moved in the outer lens barrel e to adjust the air gap between the lens L3 and the lens L4, and the projection lens system b
After the focusing is adjusted, the positional relationship between the outer lens barrel e and the inner lens barrel f is fixed.

In the projection lens system b, the optical axes of the lenses L1 to L3 optically appropriately arranged in the inner lens barrel f and the optical axis of the lens L4 separate from these are highly accurate. Need to match. For this reason, in the projection lens device a, the positioning pins k, k,... Formed integrally with the rear end surface of the external lens barrel e are provided on the rear end surface, and the positioning pins k, k are formed on the lens holding plate h. ,... Are provided with insertion holes m, m,.

At the time of assembling to the coupler g, the positioning pins k, k,... Are inserted through the insertion holes m, m,.
.. Are designed so that the optical axes of the lenses L1 to L3 and the lens L4 coincide with each other by making the front end portion abut the outer peripheral surface n of the flange of the lens L4.

[0011]

In the projection lens apparatus a, the lens L4 is fixed to the coupler g using the lens holding plate h, and then the lens barrel d is attached to the lens holding plate h. The structure is fixed. At this time, when the positioning pins k, k,... Formed integrally and protruding from the external lens barrel e come into contact with the outer peripheral surface n of the lens L4, the optical axes of the lenses L1 to L3 and the optical axis of the lens L4 , And the position and size of the positioning pins k, k,... And the shape of the outer peripheral surface n of the flange of the lens L4.
The optical axes of the lenses L1 to L3 attached to the inner lens barrel f are often changed due to variations in the processing accuracy and molding precision of the outer shape of the outer lens barrel e, or variations in assembly accuracy when each part is mounted. And the optical axis of the lens L4, there is a problem that the image quality of the projected image is deteriorated.

In view of the above, the projection lens apparatus of the present invention improves the assembling accuracy so that the optical axis of each lens in the projection lens system does not shift so that a high quality projected image can be obtained. Is the subject.

[0013]

According to the present invention, at least one of the lenses constituting the projection lens system is formed integrally with a lens barrel in order to solve the above problems.

Therefore, the positional relationship between the lens barrel and the lens integrally formed with the lens barrel is kept constant, so that when the projection lens apparatus is assembled, the lens and the lens barrel are separated. Various optical problems which occur in the above can be solved.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a projection lens apparatus according to an embodiment of the present invention; FIG.

In the following description, when describing the up, down, left, and right directions, the up and down directions in FIG. 2 are referred to as the up and down directions, respectively. The direction (the longitudinal direction of the projection lens device) is referred to as the front-back direction.

A projection lens device 1 used as an image projection device for a projection television has a projection lens system 2 as shown in FIG. One end of the projection lens device 1 is a cathode ray tube 3 functioning as an image display device.
Connected to.

The projection lens system 2 includes a plurality of single lenses L1, L2, L3 each having an appropriate shape in order from the front side.
And L4, and is disposed in the lens barrel 4.

The lens barrel 4 includes an outer barrel 5 and an inner barrel 6 rotatably and slidably disposed in the outer barrel 5.

The lenses L1, L2 and L3 of the lenses L1 to L4 constituting the projection lens system 2 are held and fixed at predetermined positions inside the inner lens barrel 6, respectively. The lens L4 located closest to the cathode ray tube 3 will be described later.

The inner lens barrel 6 has a front part 7 which is one third of the front part having a cylindrical shape, and a rear part 8 which is about two thirds of the rear part having a rearward opening. The diameter is gradually reduced.

Further, as shown in FIG. 1, the inner lens barrel 6 holding the lenses L1, L2, L3 is mounted on a lens barrel portion 9 located in front of the outer lens barrel 5 formed integrally with the lens L4. It is fitted inside. The lens barrel 9 and the lens L4 are, for example, integrally formed by a so-called two-color molding of the colorless and opaque lens barrel 9 and the colorless transparent lens L4.

That is, as shown in FIGS. 1 and 3, the outer barrel 5 has an appearance in which the front end is open and the rear end is closed by the lens L4. The side is a barrel portion 9 having a substantially cylindrical shape, and a dome-shaped lens L4 projecting rearward from the rear end of the barrel portion 9 is integrally formed. And the lens L
The optical axis 4 is defined to pass through a predetermined position in the lens barrel 9. Further, the lens barrel portion 9 has an inner surface 9a at a portion further rearward from a portion that is substantially one third closer to the rear from the opening end.
Shape such that the opening diameter becomes smaller as it goes down,
That is, it is formed in a substantially tapered shape.

The outer peripheral surface at the boundary between the lens barrel 9 of the external lens barrel 5 and the lens L4 whose rear end is closed is shown in FIG.
As shown in FIG. 3, a substantially square flange 10 is integrally provided as viewed from the front.

The external lens barrel 5 having such a shape is shown in FIG.
As shown in (1), it is connected to the cathode ray tube 3 with a coupler 11 interposed therebetween.

As shown in FIGS. 1 and 4, the coupler 11 has a main portion 12 having a short cylindrical shape with open front and rear ends.
And a generally rectangular flange 13 as viewed from the front, which is integrally protruded from the outer peripheral surface of the rear end of the main portion 12. The front and rear end faces 12a, 12b of the main portion 12 are also provided.
Are formed along the opening edge.

In the grooves 14, 14 of the coupler 11, seal rubbers 15, 15 each having a substantially ring shape are fitted. Further, bosses 16, 16,... For fixing the external lens barrel 5 are formed at a plurality of positions appropriately separated in the circumferential direction on the outer peripheral surface of the main portion 12.

The coupler 11 and the lens barrel 4 are connected as follows. That is, as shown in FIG. 1, the outer peripheral portion of the lens L4 of the external lens barrel 4 is placed on the front open end 12a of the coupler 11, and the flange 10 of the external lens barrel 4 is connected to the bosses 16, 16,. ..Screw 1
By screwing using 7, 17, ...
The lens barrel 4 and the coupler 11 are connected and fixed.

As shown in FIG. 1, a substantially plate-shaped CRT holding plate 18 is attached to the cathode ray tube 3 from the rear side. The CRT press plate 18 has a frame shape with an insertion hole 18a formed in the center.

Thus, the coupler 11 and the cathode ray tube 3
They are connected as follows. That is, the rear end 12b of the coupler 11 is placed on the image display surface 3a of the cathode ray tube 3, and the CRT press plate 18 is attached from the rear side of the cathode ray tube 3, and as shown in FIG. 18 and coupler 1
With the front part of the cathode ray tube 3 sandwiched between
Screw the T holding plate 18 and the flange 13 of the coupler 11
By screwing using 9, 19, ...
The coupler 11 and the cathode ray tube 3 are connected and fixed.

Then, the front and rear openings of the coupler 11 are closed by the lens L4 and the cathode ray tube 3, respectively, so that a space is formed therein, and the sealing rubber sandwiched between the coupler 11, the lens L4 and the cathode ray tube 3, respectively. The inside is sealed by 15, 15.

In the space formed by the lens L4, the cathode ray tube 3, and the coupler 11, the transparency is high.
A liquid 20 having a refractive index of about 43 is filled by an appropriate method, and the surface of the lens L4 and the display surface 3a of the cathode ray tube 3 are filled.
Is filled with the liquid 20 and the liquid 20
Functions as a so-called optical coupling.

As described above, in the projection lens device 1, the lens closest to the cathode ray tube is attached to the coupler, and the internal lens barrel to which the other lens is fixed is mounted on the coupler, as in the conventional projection lens device. This is not a structure in which an external lens barrel to be supported is attached, but a structure in which the external lens barrel 5 of the lens barrel 4 and the lens L4 located closest to the cathode ray tube 3 are integrally formed. And the positional relationship between the lens L4 and the external lens barrel 5 becomes constant.
The inner lens barrel 6 is moved within the outer lens barrel 5 with reference to the inner surface of the lens, and the air gap between the lens L4 and the lens L3 adjacent thereto is adjusted to adjust the focusing of the projection lens system 2. The optical axis of the lens L4 and the other lenses L1, L2, and L3 fixed to the inner lens barrel coincide with each other only by performing this operation.

[0034]

As is apparent from the above description, in the projection lens apparatus of the present invention, at least one of the lenses constituting the projection lens system is formed integrally with the lens barrel. When the positional relationship between the lens barrel and the lens integrally formed with the lens barrel is kept constant, and the lens and the lens barrel are separated from each other, the processing or molding error of the lens and the projection lens Various optical inconveniences caused by variations in external dimensions of component parts and assembly errors can be eliminated, the number of components can be reduced, and cost and production efficiency can be improved.

According to the second aspect of the present invention, the lens formed integrally with the lens barrel is a lens located closest to the image display device, and the lens barrel is a part of the lens. Since the lens is connected to the coupler, it is possible to eliminate an optical defect due to an assembly error as compared with a case where the lens is attached to the coupler by itself and the coupler is connected to the lens barrel.

According to the third aspect of the present invention, the lens barrel comprises an external lens barrel and an internal lens barrel, and the lens constituting the projection lens system is such that the lens closest to the image display device is the external mirror. Since the lens is formed integrally with the tube and another lens is arranged in the inner lens barrel, the optical adjustment of the projection lens system can be performed only by moving the inner lens barrel in the outer lens barrel.

Further, in the invention according to claim 4, the coupler is located between the lens formed integrally with the external lens barrel and the image display device, and the surface of the lens and the surface of the image display device are arranged. Is filled with a liquid having a high degree of transparency, so that the quality of the projected image can be improved and the image display device can efficiently radiate heat.

It should be noted that the specific shapes and structures of the respective parts shown in the above-described embodiment are merely examples for embodying the present invention, and the technical features of the present invention are not limited thereto. The scope should not be construed as limiting.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the projection lens device of the present invention together with FIG. 2 to FIG. 4, and is a view showing a state where the projection lens device is partially cut away when viewed from above.

FIG. 2 is a front view of the projection lens device.

FIG. 3 is a perspective view of an external lens barrel.

FIG. 4 is a front view of the coupler.

FIG. 5 is a view showing a state in which a part of the conventional projection lens device is cut away when viewed from above.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Projection lens apparatus, 2 ... Projection lens system, L1 ... Lens, L2 ... Lens, L3 ... Lens, L4 ... Lens, 3 ...
Image display device, 4: lens barrel, 5: outer barrel, 6: inner barrel, 11: coupler, 20: liquid

Claims (4)

[Claims] An image display device, a projection lens system including a plurality of lenses for projecting a display image of the image display device, a lens barrel in which the projection lens system is disposed, and the image In a projection lens device having a coupler for connecting a display device and a lens barrel, at least one of lenses constituting the projection lens system is provided.
A projection lens device, wherein one lens is formed integrally with the lens barrel. 2. A lens formed integrally with a lens barrel, which is located closest to the image display device, wherein the lens barrel is connected to a coupler at the lens. 2. The projection lens device according to 1. 3. A lens barrel comprising an outer barrel and an inner barrel, wherein a lens constituting a projection lens system has a lens closest to the image display device formed integrally with the outer barrel.
3. The projection lens device according to claim 1, wherein another lens is disposed in the inner lens barrel. 4. A coupler is located between a lens integrally formed with an external lens barrel and an image display device, and a space between a surface of the lens and a surface of the image display device is filled with a highly transparent liquid. The projection lens device according to claim 3, wherein the projection lens device is used.