JP2507166B2 - Projection television - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection television apparatus, and more particularly to prevention of flare light generated in a projection lens.

[Conventional technology]

FIG. 3 (a) shows a conventional projection type television device, in which 1 is a CRT, 2 is a projection lens unit constituted by a plurality of lens groups, 3 is projection light constituting a central image, 4 is projection light that constitutes the peripheral image, 5 is flare light, and 6
Is the screen.

As shown in FIG. 3A, in the television device configured to project the image light of the CRT 1 on the screen 6 through the projection lens unit 2, the projection light 3 forming the central image is normal light only. However, the projection light 4 forming the peripheral image includes not only the normal light but also the flare light 5 deviated from the original optical path due to the aberration of the peripheral portion of the lens. Therefore, the peripheral image on the screen 6 has a distorted contour due to the flare phenomenon. There is a method of correcting the aberration by increasing the number of constituent lenses of the projection lens in order to improve the flare phenomenon of the peripheral image, but there is a problem that the cost of the lens becomes high. So, as a simple method to remove flare,
There is a method to attach a diaphragm to the projection lens.

In order to improve the flare phenomenon, FIG. 3 (b) shows that an annular diaphragm 7 is provided at the screen side end of the projection lens unit 2 to block the peripheral portion through which the flare light passes.

Further, FIG. 4 is a diagram showing a conventional projection television apparatus in which a stereoscopic diaphragm is arranged in the projection lens section for the purpose of reducing flare light. The stereoscopic diaphragm 8 is as shown in the enlarged view of FIG. In addition, it is composed of a plurality of blades 8A and a cylindrical portion 8B. The flare light is blocked by the blade 8A of the solid diaphragm,
Almost all normal light passes through without being blocked. In this way, the flare phenomenon can be prevented without reducing the amount of projection light.

[Problems to be Solved by the Invention]

The conventional projection television device is configured as described above, and the one shown in FIG. 3 (b) has a problem that the screen becomes dark because the projection light amount is reduced by the annular diaphragm 7. Further, in the case where the three-dimensional diaphragm shown in FIGS. 4 and 5 is provided, the three-dimensional diaphragm 8 having a plurality of blades becomes complicated, which increases the manufacturing cost and complicates the manufacturing process. Further, it is necessary to arrange the stereoscopic diaphragm at a position corresponding to the shape of the CRT image screen (for example, the aspect ratio), but there is a problem in that the structure of this stereoscopic diaphragm causes a deviation such as rotation of the cylindrical portion 8B. .

The present invention has been made to solve the above-mentioned problems, and it is possible to shield flare light from the peripheral portion of the screen without darkening the central portion of the screen, and it is inexpensive, the manufacturing process is simple, and the mounting process is further improved. An object of the present invention is to obtain a projection type television device having a projection lens with high positional accuracy.

[Means for solving the problem]

A projection type television device according to the present invention is characterized in that, among a plurality of single lenses, on a single lens surface close to the screen side,
A light-shielding pattern for shielding flare light is provided, and the shape of the light-shielding pattern is a substantially isosceles trapezoidal pattern with a convex pattern added to approximately the center of the two oblique sides of the isosceles trapezoid. Further, the light-shielding pattern is arranged at a position corresponding to the aspect ratio of the screen of the image light emitting portion so as to shield the flare light generated in the projection lens.

Further, the light shielding pattern is formed by printing on the curved surface of the single lens.

[Operation] The light-shielding pattern provided on the lens surface in the present invention effectively shields the flare light on the peripheral portion of the screen, and prevents the normal light from being impaired as much as possible, and at the same time, makes it possible to form a light ray that forms an image in the central portion of the screen. Since it is provided in a position and shape so as not to be shielded, it is possible to secure practically sufficient screen brightness.

In addition, since the member for holding the light shielding pattern is unnecessary by printing the light shielding pattern on the lens surface, it is possible to reduce the manufacturing cost, simplify the manufacturing process, and improve the accuracy of the position.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the shape and position of a light-shielding pattern 10 printed on the lens surface of a projection television device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the projection lens section. In the figure, 2 is the projection lens section, which is composed of a plurality of single lenses 2a to 2g, and 11 is projection light projected from the CRT 1 to the lens 2g. The liquid layer 11 is provided to prevent reflection, and the liquid layer 11 also serves as a cooling for the CRT 1. Reference numeral 9 denotes a lens surface of the upper surface of the lens 2c provided with the light shielding pattern 10 of FIG. 1 by printing. The position of this lens surface 9 is checked by ray tracing the path of the ray that becomes flare light in the light flux that forms an image peripheral portion, and normal light that forms an image peripheral portion is not blocked, but only flare light is blocked. However, the position is determined so that the light flux that forms an image at the center of the screen is not blocked as much as possible. A method for determining the position of the lens surface on which the light shielding pattern is attached will be described below.

FIG. 6 shows a light beam that forms an image at the center of the image on the lens surface 9.
12 and a position 13 through which a light beam that becomes a flare light passes among the light beams that form an image on the peripheral portion of the screen. Moreover, in FIG.
The surface of the 2f on the CRT side is 14. FIG. 7 shows a position 16 through which a light beam, which is a flare light, of the light beam 15 which forms an image at the center of the image on the lens surface 14 and the light beam which forms an image on the periphery of the screen.
In FIG. 6, a position 13 where the flare light beam passes
By blocking the light, the flare light of the peripheral image can be removed.

The flare light can also be removed by blocking the position 16 where the light beam which becomes the flare light passes in FIG.
However, the position 13 where the flare light passes or
When 16 is shielded, the light fluxes 12 and 15 that form an image at the center of the screen are also partially shielded, and the screen becomes dark. Therefore, the same simulation as the simulations shown in FIGS. 6 and 7 is performed on all lens surfaces for the lens surface in which the ratio of blocking the light fluxes 12 and 15 forming the image at the center of the screen while reducing the flare light is reduced. The lens surface 9 is determined as the surface on which the light shielding pattern is arranged. In general, flare light is likely to be generated at a place where the image height of the projection lens is high, and in a projection television, four corners in the diagonal direction of the screen are projected using a place where the image height of the projection lens is high. The purpose of this projection lens is to block the flare light at the four corners of the screen, and the position of the light blocking pattern 10 on the lens surface 9 in FIG. 1 corresponds to the CRT image screen shape (for example, to the aspect ratio of the CRT screen). Corresponding position)
It has become.

Next, the operation will be described.

The light-shielding pattern 10 shown in FIG. 1 shields the flare light of the peripheral light on the screen generated in the projection lens unit 2 when the image light is projected. The shape of the light shielding pattern 10 is
In order that the flare on the periphery of the screen on the projection screen does not pose a practical problem, it is determined by a ray tracing simulation of flare light in the light flux imaged on the periphery of the screen and an actual projection experiment.

Further, although the projection light to the peripheral portion of the screen is partly blocked by the light-shielding pattern 10, it is estimated that the decrease in the projection light amount is about 15%, and practically sufficient brightness is obtained at the center of the screen.

As described above, in this embodiment, since the light blocking pattern for blocking the flare light is provided on the lens surface, the flare light can be effectively emitted while ensuring a sufficient light amount of the projection light without increasing the number of lenses. It can be reduced. Further, since the light-shielding pattern is provided by printing on the lens surface, a holding member for the light-shielding pattern is not required, which reduces the manufacturing cost.
The manufacturing process can be simplified and the position can be made more precise.

The shape of the light-shielding pattern 10 is not limited to that shown in FIG. 1, and may be any shape that can effectively shield flare light.

Further, although the light blocking pattern 10 is provided on the lens 2c in the above embodiment, the lens provided with the light blocking pattern 10 is not limited to this, and may be provided on another lens.

Furthermore, the light-shielding pattern 10 may be provided on the lens surface as a sticker instead of printing.

〔The invention's effect〕

As described above, according to the projection television device of the present invention, the shape and position of the projection television device are set so as to effectively block the flare light in the peripheral portion of the screen and not shield the projection light in the central portion of the screen. Since the light-shielding pattern is provided on the lens part,
The effect of flare light can be sufficiently suppressed while maintaining practically sufficient screen brightness. Further, since the light-shielding pattern is directly printed on the lens surface, the manufacturing cost is low, the manufacturing process can be simplified, and the accuracy of the mounting position is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a shape of a light-shielding pattern on a lens of a projection television device according to an embodiment of the present invention, and FIG. 2 is a cross section of a projection lens portion of a projection television device according to an embodiment of the present invention. FIGS. 3A and 3B are views showing a conventional projection type television device, FIG. 3B is a view showing a conventional projection type television device provided with an annular diaphragm, and FIG. 4 is a stereoscopic diaphragm. FIG. 5 is a view showing a conventional projection type television device provided, FIG. 5 is an enlarged view of a portion of a stereoscopic diaphragm of the projection type television device of FIG. 4, and FIGS. 6 and 7 form an image at the center of the screen. It is a figure which shows the position which the light beam used as a flare light passes among a light beam and the light beam which forms an image in the periphery of a screen. In the figure, 1 is a CRT, 2 is a projection lens unit, 9 is a lens surface provided with a light blocking pattern, and 10 is a light blocking pattern. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (2)

(57) [Claims] 1. A video light emitting section for emitting video light, and a projection lens section comprising a plurality of single lenses having the same optical axis for entering the projected video light and projecting it on a screen. In a projection television apparatus having a plurality of single lenses, a light blocking pattern for blocking flare light is provided on a single lens close to the screen side among the plurality of single lenses, and the shape of the light blocking pattern is formed into a substantially isosceles shape. The trapezoidal pattern has a shape in which a convex pattern is added to each of the substantially central portions of the two oblique sides of the isosceles trapezoid, and the light shielding pattern is arranged at a position corresponding to the aspect ratio of the screen of the image light emitting portion. A projection type television device characterized by the above. 2. The projection television apparatus according to claim 1, wherein the light-shielding pattern is formed by printing on a curved surface of a single lens.