Panel 'F' Square Fluorescent Lamp
The Panel F is a most unusual lamp which was conceived by GE and BTH Mazda during the late 1950's. GE launched it at the World's Fair in 1964-65, but it was withdrawn just a few years later due to production difficulties. BTH never put the lamps into production and followed a different approach, culminating in the famous Thorn 2D lamp 15 years later.

Panel F consists of two flat sheets of soft glass which have been specially shaped by a novel vacuum forming process, in which the heated glass panels were sucked down over a mould by vacuum. Parallel tubular sections are moulded into the back panel to contain the discharge, and thirty-six dimples are impressed into the front face to increase luminous efficacy and provide a more attractive surface. With the aid of a frit glass sealing material, the two panels are fused together all around the rim, and at several points across the centre of the panel to ensure that the discharge follows an M-shaped path over the whole area.

Electrodes are housed behind the dimples adjacent to each cap, these being standard fluorescent stick coils, complete with anode probes as found in VHO style tubes. Their dumet lead wires are sandwiched in between the two panels and sealed in the glass frit. In British lamps an exhaust tube was also sealed through the panels in the same fashion, but in this earlier American sample two exhaust tubes are affixed to the rear chambers. An external metal stripe electrode is painted onto the rear of the tube in a fork shape, and must be earthed for reliable starting. By coating the front face with a deluxe white phosphor and the rear with a high efficacy cool-white as has been done in this "Panel Deluxe" lamp, good colour rendering and high efficacy are achieved.
Manufacturer: General Electric Co. of U.S.A.
Lamp Power: 80 or 50 Watts
Lamp Current: 0.600 Amps
Lamp Voltage:
Cap Type: 2x GX7.9 recessed bi-pin Bakelite
Bulb Finish: Front: Deluxe Warm White Rear: Cool White
Bulb Type: FP-300S FP-12S (in eighths/inch)
Panel Dimensions: 295 x 295 mm 11 5/8 x 11 5/8 inches
Panel Depth: 38 mm 1 1/2 inches
Arc Length: 1500 mm 60 inches
Electrodes: Stick coil with anode probe Trimetallic oxide emitter
Inner Atmosphere: Ar | Hg
Luminous Flux (80/50W): 4200 / 2800 lm (100hrs) 3350 / 2400 lm (6000hrs)
Luminous Efficacy (80/50W) 52.5 / 56 lm/W (100hrs) 41.9 / 48 lm/W (6000hrs)
Colour Temperature & CRI: CCT: CRI:
Chromaticity Co-ordinates: CCx: CCx:
Burning Position: Universal
Rated Lifetime: 12,000 hours Rated to 50% survival
Warm-up / Re-strike Time: 4-5 minutes 5-6 minutes
Factory: NELA Piloting, Ohio U.S.A.
Date of Manufacture: June 1965
Original / Present Value: CAN$7.22 (1966) 15.18 (2001)
 
 
References: 1) General Electric "Magazine of Light", June 1965.
2) Canadian General Electric Price List, 1st June 1966.