JPH04249497A - Deflection coil raster ringing inspection method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raster ringing inspection method for deflection coils used in television receivers and the like.

0002

[Prior Art] Conventionally, raster ringing inspection of a deflection coil has been carried out by attaching a deflection coil to a cathode ray tube, energizing the cathode ray tube and the deflection coil, and displaying a crosshatch pattern on a phosphor screen to generate a horizontal scanning line. The amount of waviness in the vertical direction of the screen was visually determined, or the phosphor screen was turned on to emit light and the shading stripes were visually determined.

0003

[Problems to be Solved by the Invention] However, such conventional inspection methods are subjective methods based on human judgment, and require skill to make accurate judgments. The drawback was that it required time.

An object of the present invention is to provide a raster ringing inspection method for a deflection yoke that solves these problems.

[0005]

[Means for Solving the Problems] In order to solve this problem, the present invention provides a structure in which, when a deflection yoke is attached to a cathode ray tube, a deflection coil is attached to a portion sandwiched between the inner surface of the deflection yoke and the outer surface of the cathode ray tube. A ringing voltage is detected by installing an element that detects a magnetic field.

[0006]

[Operation] With this method, it becomes possible to detect the magnetic field that causes raster ringing using an element that detects the magnetic field produced by the deflection coil, and it is possible to determine raster ringing as a physical quantity.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of a cathode ray tube in one embodiment of the present invention. FIG. 2 is a diagram similarly viewed from the electron gun side of the cathode ray tube. 1 and 2, reference numeral 1 denotes a cathode ray tube for inspecting raster ringing of a deflection coil (hereinafter referred to as cathode ray tube for inspection 1). Similarly, 2 is an element that detects the magnetic field produced by the deflection coil (hereinafter referred to as magnetic field detection element 2). As shown in FIG. 2, the magnetic field detection element 2 is mounted diagonally to the left of the inspection cathode ray tube 1, but it may be mounted in another direction. In addition, the magnetic field detection element 2
Although there is only one, there may be more than one. FIG. 3 is a side view of the deflection coil during raster ringing inspection. 3 is a deflection coil to be tested at the time of inspection. As shown in FIG. 3, the magnetic field detection element 2 is attached to a portion where the inner surface of the opening on the fluorescent screen side of the cathode ray tube of the test deflection coil 3 and the surface of the neck portion on the electron gun side of the test cathode ray tube 1 match. .

In one embodiment of the present invention, the magnetic field detection element 2
is an air-core coil made by winding a conducting wire about twice as shown in FIG. 4, but any element that detects a magnetic field may be used, such as an air-core coil made of a flexible printed wiring board or a Hall element.

A raster ringing inspection method for the deflection coil constructed as described above will be explained with reference to FIGS. 3 and 5. As shown in Figure 3, the deflection coil 3 under test
is attached to the test cathode ray tube 1, and when the test cathode ray tube 1 and the test deflection coil 3 are energized so that an image appears on the fluorescent screen of the test cathode ray tube 1, the terminal of the magnetic field detection element 2 will be
A voltage waveform as shown in 4 in FIG. 5 is obtained, and raster ringing of the deflection coil can be inspected by the ringing voltage shown in part 5 of voltage waveform 4. The amount of vertical undulation 6 of the horizontal scanning line of the cross-hatch pattern displayed on the cathode ray tube fluorescent screen shown in FIG. 6, the gradation stripes 7 due to raster ringing when the entire fluorescent screen is illuminated as shown in FIG. 7, and the ringing voltage shown in FIG. 5 is proportional.

0010

Effects of the Invention As described above, the present invention provides a structure in which, when a deflection coil is attached to a cathode ray tube, the inner surface of the opening on the cathode ray tube fluorescent screen side and the neck section on the cathode ray tube electron gun side coincide with each other. By installing an element that detects the magnetic field generated by the deflection coil, it becomes possible to detect the magnetic field that causes raster ringing, and it is possible to judge raster ringing as a physical quantity, making it possible to detect the magnetic field that causes raster ringing. It has superior inspection accuracy compared to the subjective method of human visual inspection, is an inspection method suitable for mass production, and can reduce costs by shortening inspection time, making it of great industrial value.

[Brief explanation of the drawing]

FIG. 1: Side view of a cathode ray tube in one embodiment of the present invention.

[
FIG. 2: A diagram of a cathode ray tube in an embodiment of the present invention seen from the electron gun side.

FIG. 3 is a side view of a deflection coil during raster ringing inspection in an embodiment of the present invention.

FIG. 4 is a schematic diagram of an element that detects the magnetic field of a deflection coil in an embodiment of the present invention.

[Fig. 5] Voltage waveform diagram due to the magnetic field that was generating raster ringing detected by the element that detects the magnetic field of the deflection coil in one embodiment of the present invention.

[Figure 6] Illustration of crosshatch pattern and raster ringing displayed on cathode ray tube fluorescent screen

[Figure 7] Illustration of shading stripes due to raster ringing when the entire fluorescent screen of a cathode ray tube is illuminated

[Explanation of symbols] 1 Cathode ray tube for raster ringing test 2 Element for detecting the magnetic field of the deflection coil 3 Test deflection coil 4 Voltage waveform generated in the element for detecting the magnetic field of the deflection coil 5 Ringing voltage

Claims (1)

[Claims] Claim 1: A deflection device in which, when a deflection coil is attached to a cathode ray tube, an element for detecting a magnetic field generated by the deflection coil is attached to a portion sandwiched between the inner surface of the deflection coil and the outer surface of the cathode ray tube to detect ringing voltage. Coil raster ringing inspection method.