Vacuum fluorescent display having x-ray shielding cap

A vacuum fluorescent display comprising:

• a cathode electrode for emitting electrons;
• a grid electrode for extracting the electrons from said cathode electrode;
• an anode electrode for accelerating the electrons extracted from said cathode electrode
• at least one envelope which accommodates said cathode electrode, said grid electrode, and said anode electrode in a vacuum space and has a display portion having light transmission properties;
• a phosphor layer formed on an inner surface of the display portion of said envelope and adapted to emit light upon bombardment of the electrons accelerated by said anode electrode;
• and a cap made of an X-ray shielding material and supported outside said envelope so as to surround the display portion of said envelope through a gap, said cap having a light exit surface from which the light emitted from said phosphor layer emerges through the display portion of said envelope,
• wherein said envelope comprises a plurality of envelopes corresponding to a plurality of colors, and
• said cap surrounds display portions of the plurality of envelopes all together.

A vacuum fluorescent display comprising:

• a cathode electrode for emitting electrons;
• a grid electrode for extracting the electrons from said cathode electrode;
• an anode electrode for accelerating the electrons extracted from said cathode electrode;
• at least one envelope which accommodates said cathode electrode, said grid electrode, and said anode electrode in a vacuum space, wherein the envelope comprises a display portion having light transmission properties, a phosphor layer formed on an inner surface of the display portion of said envelope and adapted to emit light upon bombardment of the electrons accelerated by said anode electrode;
• and a cap made of an X-ray shielding material and supported outside said envelope so as to surround the display portion of said envelope through a gap, said cap having a light exit surface from which the light emitted from said phosphor layer emerges through the display portion of said envelope and having a cylindrical-shaped bottom to cover the display portion of the envelope and a side surface of the envelope, a stem in which a plurality of lead pins to be connected to said electrodes are buried and which has an outer diameter slightly larger than that of said envelope, and a portion between a tip of an opening of said cap and said envelope is sealed by the stem to form the gap;
• wherein said cap surrounds said envelope entirely.