| (19) |
 |
|
(11) |
EP 0 241 599 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
22.03.1989 Bulletin 1989/12 |
| (43) |
Date of publication A2: |
|
21.10.1987 Bulletin 1987/43 |
| (22) |
Date of filing: 29.12.1986 |
|
| (51) |
International Patent Classification (IPC)4: H01K 1/50 |
|
| (84) |
Designated Contracting States: |
|
FR GB NL |
| (30) |
Priority: |
14.04.1986 JP 55743/86
|
| (71) |
Applicant: Stanley Electric Co., Ltd. |
|
Meguro-ku
Tokyo 153 (JP) |
|
| (72) |
Inventors: |
|
- Motooka, Hidetaka
Yokohama-shi
Kanagawa-ken (JP)
- Chiba, Masatoshi
Tokyo (JP)
- Murakami, Yukio
Ksukabe-shi
Saitama-ken (JP)
|
| (74) |
Representative: Schaumburg, Thoenes & Thurn |
|
Mauerkircherstrasse 31
81679 München
81679 München (DE) |
|
| |
|
| (54) |
High efficacy incandescent lamp |
(57) A high efficacy incandescent lamp having the glass bulb outer diameter smaller than
40 mm is provided, wherein the glass tube is made of soft glass; the main component
of filler gas to be filled in the glass bulb is an inactive gas whose atomic weight
is larger than 80 and whose thermal conductivity is smaller than 25 x 10⁻⁶cal·cm⁻¹·s⁻¹·deg⁻¹;
and the pressure of the filler gas is between 1 to 3.5 preferably between 1.5 to 2.5
atmospheric pressure under non excitation of said bulb.