JPS61269591A - Focus adjusting device - Google Patents

Abstract

PURPOSE:To adjust easily and exactly the focus of an optical system which is constituted of a projection lens and a cathode ray tube, by adjusting the fitting angle of an optical block by using a spacer in which thickness of the corner parts is different from each other. CONSTITUTION:A cathode ray tube, a base 3, and a lens 4 are assembled by inserting a spacer 1 which is provided with parts 5-8 whose thickness is different from each other, on four corners, between the lens 4 and the base 3, and an angle of the lens 4 is adjusted. By constitution in which inclination of this cathode ray tube side is unnecessary, and many spacers are not required, the focus of an optical system can be adjusted easily and exactly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lens focus adjustment device used in a projection television.

BACKGROUND ART As shown in Figure 2, in projection televisions, Red R
, Green G, and Blue B are projected onto the screen S through the lens optical axis Y, and are imaged at the zero point. In this case, since the light emitted from the green G cathode ray tube is a-a' as shown in FIG. 2, focus 2 Beige blur does not occur. However, since the light emitted from the red R and blue B cathode ray tubes is 4b', out-of-focus occurs by an amount of X as shown in the figure.

As a countermeasure, conventionally, the cathode ray tube is tilted in advance by a value α obtained by dividing the incident angle β by the magnification ratio m to prevent X from being out of focus. In addition, if the optical block is shared, each time the projection angle and projection size change,
As a countermeasure against out-of-focus on the lower, left, and right sides, spacers P are placed in the corners of each cathode ray tube.

Problems to be Solved by the Invention Conventionally, focus blur has been adjusted by tilting the CRT surface, but the standard dimensions of the CRT mounting surface vary widely and the tilt angle α cannot match the design standard. It was difficult to secure the

In addition, since the tilt angles of the top, bottom, left, and right sides are different, spacers with different thicknesses must be installed on each mounting surface to accommodate the projection size, resulting in a great deal of work loss. At the same time, we had to prepare numerous types of spacers. Furthermore, since the thickness of each spacer varies very little, there is a problem that it is difficult to distinguish between the spacers and that they may be installed incorrectly.

Additionally, when installing or removing the spacer, it is very difficult to install and remove the spacer because it is tilted toward the cathode ray tube, and the spacer cannot be replaced without partially removing the chassis.

Means to Solve the Problem The present invention is an optical block composed of a projection lens and a cathode ray tube, and in order to change the projection angle and projection size, the four corners of the base between the lens and the lens mounting base are integrated into a plate body. The structure is such that the mounting angle of one optical block can be adjusted by inserting the formed spacer.

action According to the present invention, there are upper and lower spacers.

Mounting with different inclination angles on the left and right sides can be easily achieved by arranging one spacer on the lens and lens mounting surfaces, and the optimum focus state can be adjusted.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the spacer 1 is inserted between the lens 2 and the lens mounting base 3, and fixed with 4.4 screws. At this time, the mounting parts 5, 6, 7 at the four corners of the spacer 1
．． 8 have different thicknesses.

Simply place the specified corner on the specified position of the cathode ray tube,
It is possible to tilt the lens at this point to adjust the optimum focus.

Effects of the Invention As described above, according to the present invention, since spacers with different thicknesses at the four corners are arranged between the lens and the lens mounting plate, replacement is very easy by simply removing the lens. Since only one spacer is required at the same time, there is no need to prepare a large number of spacers as in the past, and there is no possibility of erroneous attachment.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing a focus adjustment device 6 according to an embodiment of the present invention, and FIG. 2 is a plan view showing a projection state from an optical block in a conventional example. 1...Spacer, 2...Lens, 3.
...base, 4...screws, 6, 6, 7,
8... Parts with different thickness.

Claims (1)

[Claims] An optical block consisting of a projection lens and a cathode ray tube is provided, and spacers with different thicknesses at the four corners are inserted between the projection lens and a base for mounting the lens, so that the mounting angle of the optical block can be adjusted. Focus adjustment device.