Not sure if this goes in the vintage or the modern section as it pertains to both...

Does anyone have any information (or even pictures or diagrams) of the equipment used by lamp manufacturers to stamp the etch on the lamp ? Fluorescent lamps especially look sometimes rubber stamp-ish. Way back since the introduction of fluorescent lamps in the late 1930's manufacturers have developed intricate ways of including a date code in the etch, which obviously needed to be changed as the weeks, months and years passed. Any info on this periodic change would also be appreciated.

Modern lamps also look like a stamp of some kind. I have Hungarian fluorescent lamps that have no apparent date code ; the date is simply printed on the end cap by a computer of some kind.

Thanks in advance.

Rubber stamps are quite simple, and are quite common to print on things a batch code, manufacturer and other details. the logo and such is a single part rubber engraving, and the codes are produced as a series of blocks that are held in place by a clamp. The whole unit then simply is held in contact with a ink soaked roller and then either pressed onto the product or the product is rolled across the rubber. Generally the solvent used is either water soluble, alcohol based or MEK based for inks that need good adhesion.

For the printed date codes they use a LINX continuous inkjet printer ( or some other brands, but Linx is the most common) that is triggered when the lamp passes by and this then prints a series of dots that are directed by an electric field to make the characters needed. It is quite reliable and prints literally on any surface, I have printed onto a raw egg in a dish with no problems, and the solvent used is MEK with a variety of ink types for food grade use or general use, typically you only get black or white inks commonly. It relies on the moving object to provide the motion in the one axis along the code and either has an encoder to give steps or simply uses a timer to generate the dot lines along, with it printing the vertical lines by moving the ink droplets up or down, those not used being caught and recycled in an ink gutter that collects the dots. Very economical on ink, as it almost all gets used, with a minuscule amount going on the object being printed, though you do use solvent on a 40:1 ratio or so. with the right programming you can print almost anything that fits in the height limit and as long as you want. Other uses are as a stand alone unit where you have a fixed format and print a batch code or a product line number with a date and time on it.

Very versatile unit. If you want a look inside look up Youtube user Aussie50 and look back to his teardown of a Linx printer that he got as scrap.