JPS593819B2 - Projection type cathode ray tube device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube device used in a projection type color television receiver, and in particular, to a concave mirror of each projection type cathode ray tube for red light, blue light, and green light. The aim is to improve the brightness and contrast of the device by specifying the material of the reflective surface of the device.

Figure 1 shows the structure of a projection cathode ray tube device. 1 is an electron gun that emits an electron beam, 2 is a fluorescent surface coated with a fluorescent material for each color, and 3 is a hole in the center. These are concave mirrors sealed in a glass tube 4.

5 is a focusing coil that focuses the electron beam (broken line arrow) emitted from the electron gun 1, and 6 is a deflection coil for the electron beam.

T is the visible light (solid arrow) emitted from the fluorescent surface 2, which is reflected by the concave mirror 3 and projected forward.
This is a Schmitt lens for focusing on the subject. In a conventional projection type cathode ray tube device, a reflective surface of aluminum (Al) is formed on the inner surface of the concave mirror 3.

This is because the reflective surface of Al has a uniformly high reflectance of 90% over a wide wavelength range from the near ultraviolet to the visible region, as shown in the reflection spectrum in FIG. That is, the Al reflective surface is advantageous in that it exhibits the same reflectance 5 no matter what color the phosphor that emits light is.
However, when the phosphor is monochromatic, it is preferable that the phosphor has a poor reflectance for light outside the emission wavelength range. In color projection televisions that use a set of three projection cathode ray tubes (red, blue, and green), contrast is said to decrease because external light entering from the front panel is uniformly reflected by a concave mirror. There were negative effects. In the present invention, the reflective surface of the concave mirror is formed so that it has a high reflectance in the emission wavelength range of the phosphor and a low reflectance in other wavelength ranges, and has a filter effect even against the incidence of external light. This is a projection type cathode ray tube device that can provide a screen with high brightness and high contrast, and one embodiment thereof will be described below. First, fluorescent surface 2
A cathode ray tube device in which a red-emitting phosphor such as Y2O2S:EU is formed has an emission spectrum with a peak at a slightly longer length of 600 nmJ, as shown in FIG.

Now, the inner surface of the concave mirror 3 is coated with gold (A
u) or copper (Cu), the reflection spectrum will be as shown in the solid line in Figure 3 for the Au reflective surface and as the same broken line for the Cu reflective surface.Compare with the Al reflective surface in Figure 2. Therefore, the reflective surfaces of Au and Cu have a high reflectance of 6 to 7% in the emission wavelength range of red light, but the reflectance decreases significantly below 600 nm.External light such as sunlight and fluorescent lamp light Since it has 70 to 80% of its intensity in the wavelength range of 600 nm or less, the reflectance of external light is lower on reflective surfaces of Au and Cu, resulting in an approximately 15% contrast improvement. In addition to the brightness increasing for CI
When calculating and comparing the E chromaticity coordinates, x = 0 for the Al reflective surface.
．． 641, y=0.357, whereas Au, Cu
On the reflecting surface, x=0,664, y=0.335,
It can be seen that the chromaticity is close to the NTSCf)Red point.

This means that the chromaticity is high and a vivid red color can be reproduced. In the case of blue light or green light, a reflective surface of silver (Ag) with a film thickness of 0.05 μm to 0.4 μm is formed on the inner surface of the concave mirror 3. This Ag reflective surface exhibits a reflection spectrum as shown in FIG. 4, and has a reflectance 7 to 8% higher than that of the conventional Al reflective surface in the emission wavelength range of blue light and green light in the figure.
On the other hand, in a wavelength range shorter than 350 nm, the reflectance decreases rapidly, and a filter effect appears on external light. From this, the brightness is improved by about 7% for each of blue light and green light. When a projection type color television receiver is configured using the three cathode ray tube devices (red, blue, and green) described above, the concave mirror has a high reflectance, resulting in high brightness, and at the same time, external light is weakened and contrast is also reduced. It becomes possible to obtain improved images. In particular, red light has improved chromaticity and becomes brighter, so when used in combination like this, a conventional concave mirror for blue and green with an Al reflective surface may be used.
Three types comprising means for converging and deflecting the electron beam emitted from the electron gun, a fluorescent surface scanned by the electron beam, and a concave mirror reflecting and projecting the light emitted from the fluorescent surface. Of the projection type cathode ray tubes, the concave mirror reflecting surface of the one for red emission is made of gold or copper, the concave mirror reflecting surface of the one for blue emission is made of silver or aluminum, and the concave mirror reflecting surface of the one for green emission is made of silver. Alternatively, by forming it from aluminum, a high reflectance can be obtained in the emission wavelength range of each color, and an image with high brightness and high contrast can be obtained.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the structure of a projection type cathode ray tube device;
The figure is a reflection spectrum diagram of an Al reflective surface, Figure 3 is a red light emission spectrum and a reflection spectrum diagram of Au and Cu reflective surfaces, and Figure 4 is a blue and green light emission spectrum and reflection of an Ag reflective surface. It is a spectrum diagram. 1... Electron gun, 2... Fluorescent surface, 3...
... Concave mirror, 5 ... Focusing coil, 6 ...
... Deflection coil, 7... Schmitt lens,
8...Screen.

Claims (1)

[Claims] 1 Equipped with a projection cathode ray tube for emitting red light, a projection cathode ray tube for blue light, and a projection cathode ray tube for green light, each of the three types of cathode ray tubes having an electron gun and an electron emitted from the electron gun. A cathode ray for a projection type color television receiver, comprising means for converging and deflecting the beam, a fluorescent surface scanned by the electron beam, and a concave mirror reflecting and projecting the light emitted from the fluorescent surface. In the tube device, the concave mirror of the projection cathode ray tube for emitting red light has a reflecting surface made of gold or copper, the concave mirror of the projection cathode ray tube for emitting blue light has a reflecting surface of silver or aluminum, and the concave mirror of the projection cathode ray tube for emitting blue light has a reflecting surface made of silver or aluminum. A projection type cathode ray tube device, wherein each of the concave mirrors of the projection type cathode ray tube has a reflecting surface made of silver or aluminum.