Hi drifand, thank you for that detail. So it didn’t take long for the patent to be realised. However, I would have rather assumed that the first double-push pencil came from Pentel, the inventor.
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This is great information. Thank you for sharing @Gunther
When you have time, could you make a new post on some of the patents you have discovered? That stuff fascinates me
Welcome to the forum I think you’ll feel right at home.
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Perhaps Pilot was first to market in 1970 while Pentel was first to patent in '68? In any case Pentel’s P1025 ‘W For Young’ is dated to 1971 or later because of the ‘Pentel’ etching on the upper body… and, it would seem Pilot had more market success with their designs.
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Yes, @Pdunc67, I will happily make a new post on a patent when I find one and think that it is worth presenting. Now and then I mention new patents but it’s more fun to show the patent along with the real product which is based on it (like the one for the Pentel Mechanica). – I find it fascinating too!
By the way, the most exciting patent search I have done so far led me to the origin of a hand-held sharpener that is still available. I was patented in 1890 
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This could be possible! I wonder when the Pentel PSD5 was introduced; maybe this was their first double-push pencil.
Do we have the „patent guy“ from twitter here? Gunther and he might be a power duo
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Thank you, @2nd_astronaut Who is that “patent guy from Twitter”?
I didn’t think that I could find the name in short time, but I did: Hsi-chi
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Most of the patents for the pens often discussed here have already been found, but it will take some time before I post them, mainly because analyzing and sorting patents is extremely time consuming, and it is not the kind of thing that you can do with your fragmented time
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Yukio Horie→堀江幸夫, the founder of Pentel, he was also the developer of some early ball pens (those with fiber tip), but not these pencils. Around that time, he is often listed as the inventor, although it was actually someone else. This often happened in their oversea patents that time.
I don’t know who is the actual inventor of DE1926208 because I can’t find the corresponding Japanese patent of it. JP19680036098, this is not the standard Japanese format for patent number. Of course I could limit the time span and searched for it by personor company’s name, but the problem is that many patents from that period cannot be searched properly cause the text information was probably generated through OCR and there were many errors.
DE1926208 mentioned the structure of double knock and Mechanica. JPY 1975000827, is only related to Mechanica, the inventor is 関谷文平. Could he be the inventor of double knock mp? I didn’t see any direct description of it.
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A very late reply. Thank you for these details! Of course this makes the search for the inventor even trickier.
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