JPS5846771A - Inspecting device for landing state - Google Patents

Abstract

PURPOSE:To ensure an accurate inspection for the landing state, by setting a rotary permanent magnet coaxially to a microscope for magnification of fluorescent screen. CONSTITUTION:A rotary support member 7 is set coaxially and rotatably to a conical transparent support leg 5 and at the lower part of the lens barrel of a microscope 4 containing a lens barrel 4. The permanent magnets 8 having opposite polarities to each other are buried at the axially symmetrical positions of the member 7. The member 7 is fitted to a lens barrel 6' for objective lens 9, and at the same time the lower edge of the member 7 is supported rotatably via the flange part of the support frame of the lens 9. An inspecting device of such constitution is set to touch the front glass 2 of a color picture tube 1 and coaxially with the center of either one of the fluorescent matters. The beam spot landing to the fluorescent matter is shifted aside by the permanent magnet. This shift is measured at the position of 180 deg.. In such way, the landing state can be inspected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for inspecting whether or not an electron beam is landing to correctly irradiate each phosphor phosphor on a phosphor screen in a color cathode ray tube. An object of the present invention is to provide a device that can accurately inspect a landing state.

In color cathode ray tubes, if the electron beams that have passed through the shadow mask do not properly irradiate each phosphor phosphor, the color purity of the screen will deteriorate. The landing state of the beam is finely adjusted to properly irradiate the electron beam onto the phosphor phosphor. When adjusting the landing state of the electron beam at such a color cathode pass, it is necessary to examine the extent to which the landing error occurs. Therefore, conventionally, an electromagnet that moves the irradiation position of the electron beam and a photoelectric element that detects the change in the amount of emitted light during the movement are installed on the front surface of the resistive surface, and a current is sequentially passed through the electromagnet in the forward direction. The landing error of the electron beam was inspected by sequentially changing the beam irradiation position in the opposite direction and detecting the resulting change in the amount of light emitted by a photoelectric element.

However, with such conventional devices, the current flowing through the electromagnet fluctuates, the magnetic field of the electromagnet is uneven, the detection sensitivity of the photoelectric element changes, or the shape of the holes in the phosphor phosphor or shadow mask changes. If it is incorrect, the landing state cannot be properly inspected, and the configuration becomes complicated as it requires a power supply, a switch, etc.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a device which has a simple configuration and is capable of accurately inspecting and inspecting the landing condition by eliminating such conventional drawbacks.

The following is the original. -Example, Tsuki, Part 5, Explain in detail.

In FIGS. 1 and 2, 1 is a color cathode ray tube, 2 is its front glass, and 3 is its fluorescent screen.

4 is a phosphor screen 3 located in front of this color cathode ray tube 1.
It is a microscope that allows you to see magnified images.

It is constructed by attaching a lens barrel 6 to a conical cylindrical transparent support leg 5. The microscope 4 has a magnification such that the phosphor phosphor on the phosphor screen 3 can be viewed in a greatly enlarged manner, and a scale is provided at the center of the field of view. A rotary support member 7 is coaxially and rotatably provided at the lower end of the lens barrel e of the microscope 4, and permanent magnets 8 with opposite polarities are embedded and supported at axially symmetrical positions. In the illustrated embodiment, the rotary support member 7 is fitted into the lens barrel 6' for the objective lens 9, and its lower end is rotatably supported by the flange portion of the support frame of the objective lens 9. Of course, it may be provided on the support leg 6 or the like in addition to this. 1o is a click mechanism for positioning the rotary support member 7 at a position rotated by eg or 18g.

Further, the support leg 6 is provided with a window 11 for rotating the rotary support member 7 with a finger from the outside.

Next, an inspection method using the inspection apparatus having such a configuration will be explained. First, as shown in FIG. 1, the supporting legs 6 of the microscope 4 are brought into contact with the front glass of the color cathode ray tube 1 and stably positioned in front of it. At this time, it is preferable to align the center axis of the microscope 4 with the center of one of the phosphor phosphors.

The relationship between the phosphor 12 and the electron beam irradiation position 13 is shown in FIGS. 3 and 4.

Here, a in each figure shows the state when no influence is exerted by the permanent magnet BVc, and a in FIG.
Fig. 4a shows a correct landing state in which the centers of the irradiation position 13 and the irradiation position 13 by the electron beam coincide, and Fig. 4a shows a state in which the center of the irradiation position deviates by an amount of mm, causing a landing error.

However, in this case, the entire surface of the phosphor 12 is irradiated and emits light in both cases, so the error cannot be detected from this alone.

Therefore, when the microscope 4 is positioned as described above and a magnetic field is applied by the permanent magnet 8, the path of the electron beam is bent by the magnetic field, and the irradiation position 13 is shifted laterally. This shifted state is shown in Figure 3.

b in FIG. 4, and are shifted upward by the same amount. At this time, the child beam is phosphor phosphor-12
Since only a portion of the area is irradiated, a portion 14 leaking into the shadow occurs. Therefore, the length of each emitting part B
is measured by the scale 13 within the field of view of the microscope 4.

Next, the rotating support member 7 is rotated 180 revolutions by hand to exactly reverse the direction of the magnetic field from the permanent magnet 8.

Then, the electron beam is now bent in the opposite direction by the same amount, and its irradiation position 13 is shifted downward. This state is the third
This is C in Figure 4. At this time, since the electron beam irradiates only a portion of the phosphor 12, the length C of the emitting portion is also measured.

Through the above measurements, the amount of deviation of the irradiation position of the electron beam in each state shown in FIG. If the sum is positive, it is a downward shift; if it is negative, it is an upward shift.

Therefore, by rotating the permanent magnet 8 as described above and measuring the emission length of the phosphor phosphor 12 at that time, it is possible to ensure that the electron beam correctly irradiates the phosphor phosphor 12 in the color cathode ray tube 1. It is possible to easily and accurately check whether the vehicle is landing or not.

Furthermore, what should be noted here is that since the permanent magnet 8 is rotated to bend the electron beam, the applied magnetic field is exactly the same no matter which direction the electron beam is bent. This means that it can be shifted by the same amount in both directions. This makes it possible to eliminate measurement errors in landing errors.

As described above, according to the present invention, a permanent magnet is rotatably installed coaxially with a microscope for magnifying the phosphor screen of a color cathode ray tube, so that the electron beam can correctly irradiate the phosphor phosphor. It is possible to check very easily and accurately whether or not there is a problem. In addition, since only the permanent magnets are provided in this way, the structure can be made extremely simple and can be obtained at low cost, and workability can also be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view of a landing condition inspection device according to an embodiment of the present invention, FIG. 2 is a bottom view thereof, and FIGS. 3 and 4 are diagrams showing its inspection condition. 1... Color cathode ray tube, 2... Front glass, 3... Fluorescent screen, 4... Microscope,
6... Support leg, 6...'... Lens barrel, 7...
...Rotation support member, 8...Permanent magnet, 9.
. . . Objective lens, 12 . . . Phosphor phosphor 113 . . . Electron beam irradiation position. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
5a Figure 3

Claims (1)

[Scope of Claims] A microscope is provided in front of the color cathode ray tube so that the fluorescent screen thereof can be viewed in an enlarged manner, and a permanent magnet for moving the irradiation position of the electron beam of the color cathode ray tube is attached to the microscope. Landing condition inspection device 0 characterized by a girder installed coaxially and rotatably on the