Digitally Curious - A Vintage LCD Watch Blog

Digitally Curious - A Vintage LCD Watch Blog

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  • Thursday, May 28th, 2009 - 3:39 pm
  • Casio BP-100 [900] Blood Pressure Monitor watch


    Today's feature is Casio's BP-100 blood pressure monitor watch. After the success of the JP-100W pulsecheck, Casio put that concept on steroids and released this model in 1993. (Or was it 1992?) It claims to measure not only the heart rate, but also the blood pressure!

    * (Just a note, Casio's sequel to the JP-100W was the JP-200W, which was released in 1992. The BP-100 is not a direct descendant of the JP series watches, but certainly builds on that technology.)

    Unlike other Casio watches of its time, this model came in a custom designed box. Not only that, it was sold in different custom package versions. I have seen a long slender cardboard box version as well as the version shown here.

    Removing the plastic shrink wrap and outer sleeve reveals a plastic case.

    Opening that case reveals the watch seated on a red velvet-like tray.

    In that tray, you will find an instructional audio cassette tape. Since I got this watch in 2008, I didn't have a cassette tape player to listen to the tape. I wonder what it sounds like!

    And if you lift that tray, you will find not one, but TWO manuals. The blue manual is the abbreviated version that briefly covers the blood pressure functions, whereas the black one covers the entire watch in detail.

    The special packaging and redundant instructional material leads me to believe that Casio intended this watch to be used by people unfamiliar with technology. I'm not sure how successful Casio was in their marketing strategy, but it's interesting to note.

    Enough about packaging, get on to the watch already!

    okay okay, relax! :)

    As a watch, the functions are pretty standard. It's got a built-in microlight, along with alarm, stopwatch and timer modes. But what makes this watch special is the blood pressure functions.

    The watch actually uses a combination of two sensor technologies.

    The pad on the left reads the pulse using a photosensor, exactly like the JP-100W. The BP-100 manual includes a schematic of this photosensor technology.

    The pad on the right is one lead of a two-lead ECG probe that's built into the watch. Can you guess where the other lead is? ... It's on the watch backplate. Those leads measure the electrical signal that accompanies your heart beat. For the system to work properly, the watch's backplate must make contact with your bare wrist. In addition, your right hand can only touch the two sensors--because if you rested your right thumb on your left wrist (or vice versa) while making this measurement, you'd create an alternate conduction path.

    But how does Casio use these sensors to measure blood pressure? Well, it does not. The watch obviously doesn't have a built-in cuff or air pump that can measure the real absolute blood pressure. Instead, it relies on a concept called "Pulse Wave Transit Time," or PWTT. I found this excellent website that describes the science in detail, so I'll leave interested readers to follow up on this link.

    To take advantage of the PWTT concept, it just so happens that you need to take the measurements at your extremities. Lucky for Casio, a wristwatch is the perfect candidate for this application!

    PWTT, by itself, can only tell you the relative changes in blood pressure, not an absolute number. Therefore, you have to input some basic data into the watch before using any of its blood pressure features. After you input your normal resting blood pressure, you're good to go. You can also input your post-exercise BP to use the more advanced functions.

    When all that's done, just press the button and relax.

    Taking a BP measurement with the watch's sensors requires very steady fingers/hands, and it can be an aggravating experience if you cannot hold still. But once you do it right, you will be greeted with this screen. Note that it also measures your heart rate.

    The watch can store upto 30 BP measurements, which is automatically timestamped.

    You can even view your past measurements in graph form. Note that I only have 3 datapoints stored in the below graph. If you had all 30 datapoints stored, it would show a nice filled graph.

    One last thing, the back plate on the BP-100 breaks two Casio conventions.

    1. It does not show the module number.
    2. It has a serial number, which is very unusual for a 90's model with resin case.

    The BP-100 was sucessful enough to have several variations and follow-up models. These include the BP-120, BP-200 and BP-300. As far as I know, they are functionally the same but have some major cosmetic changes.

    Note to people looking for this watch: Until early last year (2008) these were very rare, commanding prices well above $100 on places like eBay. But then a sudden surge of NOS (new old stock) items flooded the market and prices dove to $50 for brand new items. As of this article the NOS stock seems to have dried up, and the prices of these gems are starting to rise again. If you are looking for one, good luck!

    And if you are looking for a PDF manual for this watch, here it is!

  • Filed under: watch
  • Comments!
  • » Thanks for the Manual !!!
  • by: Roy, submitted Thursday, November 12th, 2009 - 12:38 am
  • » Sir amazing blog, I was searching the whole net for the info of how this BP measurement works, cudn find it. But found that u have listed the science behind the operation was listed in your site. Thank you very much for writing this blog to the precise details. Keep it up....
  • by: Srivatsan, submitted Wednesday, November 18th, 2009 - 2:03 pm
  • » Excellent information!. Thanks.
  • by: Felix Puga, submitted Saturday, November 21st, 2009 - 8:34 am
  • » Hello,
    I looking the BP120 series, Do you know where can I but it ? I'm base on Mexico, but I can buy it through internet. Thank you !
  • by: Jose, submitted Wednesday, December 30th, 2009 - 5:36 pm
  • » thanks mate!
  • by: TheRem, submitted Saturday, January 2nd, 2010 - 4:35 am
  • » Thanks for the Manual. I have Casio BP100 from log time ago but the Manual was lost. Thanks
  • by: Esteban, submitted Friday, February 5th, 2010 - 4:31 am
  • » ty for describ
    bt i hav a watch wen i look for bp it show me this msg " set "
    i dont know wat to do
    ty for help
  • by: chouayet, submitted Tuesday, May 4th, 2010 - 2:52 am
  • » I purchased this watch NEW when it was introduced and was "blown away" by the many features and the accuracy of the BP readings. The info enclosed did a creditable job explaining the technology but the feature I found very helpful was the Feedback feature. Back in the 90s biofeedback was the rage (even the company which employed me had a senior staff meeting where an "expert" guided us in relaxing and monitored a variable tone to gauge success. I could, however to it on my own and now that, after years of neglect, I have had the battery replaced, it works fine. I have the manual somewhere but it is easier to download it, thanks to you. GREAT SERVICE!
  • by: Harry Geruldsen, submitted Saturday, May 15th, 2010 - 3:12 pm
  • » I have already sent my congratulations and thanks but if anyone is interested, my BP-100 has a serial number of: 1060178244 so if you have any information on how early in the production cycle my watch is, I would love to know.
  • by: Harry Geruldsen, submitted Saturday, May 15th, 2010 - 3:40 pm
  • » Where i can buy new Casio BP-100? Can't find it anywhere.
  • by: uplifting, submitted Monday, June 28th, 2010 - 8:29 am
  • » Hi guys, thanks for the info, very helpfull. I got this old bp 100 CASIO from my father in law and somehhow water got in while i tried to clean it. The screen is gone black and i was wondering if is posible to repair this damage. Any help or advice would be greatly apreciated. Thank you for your attention.
  • by: Eri-on, submitted Friday, July 9th, 2010 - 4:34 am
  • » what kind of battery does this watch require?????
  • by: ram, submitted Friday, July 16th, 2010 - 8:10 am
  • » Thx 4 Manual, i am search this product... Where i can buy this one??? and ho much the price i should pay???

    Thx b4 dear Moderator..
    Best regards,

  • by: Alvano, submitted Tuesday, August 3rd, 2010 - 3:41 am
  • » Thank you very much for your help to download this manual. Finally, I can put this watch to work. Thks thousand times.
  • by: Marc Nassar, submitted Monday, January 10th, 2011 - 12:12 pm
  • » This is an awesome watch with the most useful features. I bought it when it was introduced and put it in storage when the battery ran out. Now I have bought 5 CR2016 batteries for $1 from Ebay and installed one in the watch. It works fine as good as new after 15 years!
  • by: Vikram, submitted Sunday, March 20th, 2011 - 9:08 am
  • » I've been looking for the manual for long long time. You are so great. Thank you very much for your sharing.
  • by: Atomboy, submitted Tuesday, March 22nd, 2011 - 8:16 am
  • » Many thanks for a most helpful blog. Really appreciated getting hold of the PDF for them manual which I have managed to lose over the years. Keep up the good work.
  • by: Dr David, submitted Wednesday, August 3rd, 2011 - 2:04 am
  • » Thank you for BP-120, I have more than 10 years, I am very happy. Thank for manual.
  • by: Marsicek,Czech, submitted Friday, August 19th, 2011 - 8:50 am
  • » I just wanted to say thank you for putting this manual online. I actually bought the BP-100 watch when it first came out, way back when (and I know that dates me). But when I finally found the watch again, I couldn't find the instructions to use it correctly. Major thanks to you and your willingness to put it online!
  • by: Kay C, submitted Thursday, November 3rd, 2011 - 5:57 pm
  • » i bought this watch when it first came out, alas it was stolen, now that i need to monitoe my BP regularly, I want another one. Anyoe know where to buy this now ?
  • by: toyger, submitted Friday, November 25th, 2011 - 10:05 pm
  • » Definitely was released sometime 1992 cause my mom had one for when she was pregnant with me and I was born then.
  • by: Sky, submitted Thursday, December 22nd, 2011 - 11:04 pm
  • » How do you change the battery? I opened the four screws and the back was intact with the watch. but how do you get to the battery?
  • by: Jorge, submitted Monday, March 12th, 2012 - 8:34 pm
  • » Battery is of the coin size/shape Lithium type. I can't remember the exact type but the back is easy to remove, just four small screws, to check. Changing the battery is quite easy although replacing the thin rubber o-ring, situated between the body and the backplate can be a bit fiddly. I got mine in 1992 and it still works fine.
  • by: Eddie, submitted Sunday, July 8th, 2012 - 4:02 am
  • » Very good sir !
  • by: AmerKhan, submitted Sunday, September 9th, 2012 - 5:46 am
  • » Thanks for the manual download - bought this watch at a garage sale without one & now it's fully functional.
  • by: Dakota, submitted Wednesday, November 7th, 2012 - 5:01 pm
  • » Thank you very much for your so useful and educative articles. Cheers from Patagonia, Argentina.
  • by: Sergio Wagner, submitted Friday, November 30th, 2012 - 12:49 pm
  • » nice information sir
    a complete detail thanks
  • by: shanky, submitted Wednesday, May 1st, 2013 - 5:51 am
  • » thanks for the manual user guide ...
  • by: Paunk Platina, submitted Wednesday, June 19th, 2013 - 11:45 am
  • » When I bought one of these used on eBay a few years ago, I didn't realize it had to be pre-configured and calibrated before use. I wondered why my (and everyone else who tried it) blood pressure was always 130/80! I had given up on it. Now that I've read the manual and set it up properly I find its measurements to be pretty similar to my Omron automated cuff and I'm back to wearing it daily.
  • by: John F, submitted Thursday, February 6th, 2014 - 11:59 am
  • » Hi gals and guys,
    I am shure that this watch appeared earlier than wrizzen in the article. My father sold it in his shop in Switzerland maybe in 1988 but surely in 1989. I still have the cardboard presentation unit used to show it in shop windows. Casio always has been a pioneer in electronic wrist-gadgets that worked perfectly well. Together with Seiko, of course: TV-watch, pulse-watch with belt, talking watch. Japanese are the best watchmakers!
  • by: Juri Vlk, submitted Friday, October 24th, 2014 - 6:13 am
  • » I have that model its over twenty years and works fine , its amazing what it can do .

    I Have that model its amazing what it can do

  • by: Franklin Chmara, submitted Friday, November 7th, 2014 - 12:23 pm
  • » Thank you very much. I just bought one and only can use it because of your article. Please keep it alive in the name of the old LCD Casio watches!
  • by: RCL, submitted Tuesday, April 5th, 2016 - 8:16 am
  • » Thanks for the manual. This is a great watch. One of my favorite. Works as good as the smartwatches we see nowadays.
  • by: Sergio, submitted Saturday, January 28th, 2017 - 2:22 pm
  • » Thanks a lot for the manual.
    I'd almost lost hope to find it after looking for it for years, but... it would be perfect for me if you allow me to download the manual in its Spanish version.
    And I presume Italian speaking people will say the same with the Italian version (and so on).
    Could you put at least the Spanish, French, Italian and German versions on line?
    I know it's a lot of work, but it could make some lives easier.
    Thanks in advance!
  • by: Pacu FP, submitted Friday, May 31st, 2019 - 10:40 pm
  • » Just got one for a steal with all the instructions and in perfect working order. One of my favourite watches in the 90s and still look awesome today. Really good review you did. Thank you 👍
  • by: Tom sugden, submitted Thursday, June 6th, 2019 - 1:28 am
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