JPS6290822A - Projection type cathode-ray tube device - Google Patents

Abstract

PURPOSE:To minimize the luminance reduction of the picture screen and the deterioration of the phosphor by cooling so as to improve the reliability of a projection cathode-ray tube by packing a cooling medium whose optical refractive index is equal to that of the panel glass into the central concave area on the outer surface of the panel of the cathode-ray tube. CONSTITUTION:The inner surface of the panel 11a of a projection type cathode- ray tube is made convex to form a phosphor face 12, and the outer surface of the panel 1a is made concave so that the panel glass surface may be of uniform thickness. A front panel 2 is installed in front of the tube 1a, and a cooling medium 3 whose optical refractive index is equal to that of the panel 11a is packed between the panels 2 and 11a. Therefore, the heat produced in the fluorescent screen 12 is transmitted to the cooling medium 3 through the outer surface of the panel 11a thereby reducing the temperature increase of the central area of the fluorescent screen 12. As the result, the luminance reduction of the picture screen or the deterioration of the phosphor hardly occurs thereby increasing the reliability of the cathode-ray tube 1a.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a projection cathode ray tube that has optical advantages in configuring a projection cathode ray tube device and does not cause performance deterioration of the cathode ray tube itself. Regarding equipment.

[Background of the invention]

Conventionally, when configuring a projection type cathode ray tube device, the combination with the optical system has been considered, for example, in Japanese Patent Application Laid-Open No. 58-44657.
As disclosed in the above publication, projection type cathode ray tubes in which the fluorescent surface is convex toward the electron gun have been used in some cases.

However, on the other hand, the projection type cathode ray tube requires an image as bright as possible in order to enlarge and project the image, and therefore the electrical input to the projection type cathode ray tube becomes large compared to its size.

The luminous efficiency of a phosphor decreases as the temperature rises, and if the temperature becomes too high, it deteriorates, so the phosphor surface of a projection cathode ray tube must be cooled particularly efficiently.

FIG. 2 shows a side view of a conventional projection cathode ray tube in which the fluorescent surface is convex toward the electron gun, with the fluorescent surface section taken in section.
The inner surface of the panel 11 of the projection cathode ray tube 1 is convex toward the electron gun (not shown), and a fluorescent surface 12 is formed there.

In this case, the panel 11 has a thicker glass wall at the center than at the periphery, as shown. Therefore, the fluorescent surface 1
When the heat generated in step 2 is radiated to the outside, it is difficult to radiate heat from the center of the phosphor surface, resulting in a large temperature rise at the center of the phosphor surface. As mentioned above, if the temperature rise is large, the luminous efficiency of the phosphor decreases, causing problems such as the image becoming dark in the center of the screen and the phosphor deteriorating in a short period of time.

On the other hand, it has been proposed that the outer surface of the panel is recessed along the inner fluorescent surface to make the panel glass thickness almost constant, but although the air cooling heat dissipation effect is improved, the optical characteristics are still poor.
This may be undesirable since it will differ from what is shown in the figure.

[Purpose of the invention]

The purpose of the present invention is to maintain the optical characteristics of a conventional projection cathode ray tube, in which the fluorescent surface is convex toward the electron gun, and the thickness of the central part of the panel glass is larger than that of the peripheral part. Another object of the present invention is to provide a projection multi-cathode ray tube device in which the vicinity of the phosphor surface is well cooled and the problems that occur when using the above-mentioned conventional cathode ray tube are avoided.

[Summary of the invention]

In order to achieve the above object, in the present invention, the fluorescent surface of the cathode ray tube is made convex toward the electron gun side, and at the same time, the outer surface of the cathode ray tube panel is made such that the thickness of the panel is approximately equal at the periphery and at the center. By recessing the central portion and filling this recess with a refrigerant whose optical refractive index is approximately equal to that of the panel glass, optical effects similar to those obtained when using a conventional projection type cathode ray tube with a thick central portion of the panel glass can be achieved. In addition, the fluorescent surface in the center of the panel can be cooled well.

[Embodiments of the invention]

FIG. 1 is a side view of an embodiment of the present invention, showing the vicinity of the fluorescent surface section. The inner surface of the panel lla of the projection cathode ray tube 1a according to the present invention is convex toward the electron gun side, and a fluorescent surface 12 is formed there.

The outer surface of the panel lla is recessed so that the wall thickness of the panel glass surface is approximately constant.

On the other hand, a separate front panel 2 is provided in front of the cathode ray tube 1a, and in the space between this front panel 2 and the panel lla of the cathode ray tube 1a, a coolant 3, such as ethylene glycol, whose optical refractive index is almost the same as that of the panel lla. Fill it with. 4 is a part of a heat dissipating metal such as a fin, or a device component, and
A piece of metal that also serves as heat dissipation. 5.5° is banking or adhesive.

In this way, the thickness of the panel lla is not extremely thick even at the center, so the heat generated on the fluorescent surface L2 is easily transmitted to the outer surface of the panel lla and further to the refrigerant 3. Therefore, it is possible to suppress the temperature rise in the central part of the fluorescent surface 12 to a lower level than in the conventional case, and to obtain a projection multi-cathode ray tube device with less reduction in luminous efficiency and a brighter image in the central part. On the other hand, since the optical refractive index of the panel lla and the refrigerant 3 are almost equal, no refraction of light occurs at the interface between the panel lla and the refrigerant 3, and the optical characteristics are not impaired, making it similar to the conventional one shown in Fig. 2. .

Note that the front panel 2 does not need to be a simple flat plate, and may have a curved surface that forms part of a projection lens.

〔Effect of the invention〕

As explained above, according to the present invention, the fluorescent surface of the cathode ray tube is convex toward the electron gun side, so that the optical characteristics are suitable for the device, and the fluorescent surface in the center of the cathode ray tube panel is also well cooled. A highly reliable projection multi-cathode ray tube device is obtained in which reduction in brightness and deterioration of the phosphor are unlikely to occur.

[Brief explanation of drawings]

Fig. 1 is a side view showing a section near the fluorescent surface of an embodiment of the present invention, and Fig. 2 is a cross-sectional view of the fluorescent surface of a conventional projection type cathode ray tube in which the fluorescent surface is convex toward the electron gun side. FIG. 1a - Projection type cathode ray tube according to the present invention, 2 - Front panel, 3 - Refrigerant, 4 - Part of heat dissipation metal, 5
．． 5゛.--Backing or adhesive, 1la-Panel according to the invention, 12-.-Fluorescent surface. , -l pa

Claims (1)

[Claims] In a projection type cathode ray tube device, the fluorescent surface of the cathode ray tube is made convex toward the electron gun, and at the same time the outer surface of the cathode ray tube panel is recessed in the center so that the thickness of the panel is approximately equal at the periphery and the center. A projection type cathode ray tube device, characterized in that the recess is filled with a refrigerant having an optical refractive index substantially equal to that of the panel glass.