The July 2022 issue of IEEE Spectrum is here!

Close bar

The Consumer Electronics Hall of Fame: Zojirushi Micom Electric Rice Cooker/Warmer

The Zojirushi was among the first appliances to use fuzzy logic, and made it almost impossible to ruin a pot of rice

2 min read
Photo of rice cooker.
Photo: Zojiroshi

Photo of rice cookerThe Twonky as Rice Cooker? Not quite, but the Zojirushi’s fuzzy-logic software enabled it to overcome a couple of human foibles, such as adding too much water to the rice.Photo: Zojirushi

People have been cooking rice for at least 12,000 years. And yet it was only 35 years ago that Zojirushi figured out how to make the process foolproof.

Of course, there were some notable milestones leading up to that achievement. The first consumer-oriented rice cooker was introduced by Mitsubishi in 1945. It was the first of a slew of electric cookers that used heating coils to steam rice; with these, operators had to monitor the device and turn it off when the rice was done. Toshiba introduced the first automated rice cooker in 1956. It relied on a relatively simple bimetallic switch—when all the water had been absorbed, the temperature of the metal cooking vessel would quickly rise, triggering the switch, which turned the unit off. 

Zojirushi claims to have been the first to include a feature that would keep cooked rice warm for hours. Introduced in 1965, that model relied on semiconductors to accomplish the trick. Prior to that, Zojirushi was best known for making vacuum bottles.

Then, 18 years later, came the big breakthrough. In 1983 Zojirushi introduced a rice cooker that was among the first consumer-oriented products to rely on fuzzy logic. Oddly, the company doesn’t use the term in its marketing, preferring instead to refer to the microcomputer (which it calls a “Micom”) that implements the fuzzy logic. Three and a half decades later, Zojirushi still considers everything having to do with the development of this rice cooker a trade secret and refuses to discuss any of it.

Why did the world need to apply a form of multivalued logic to the cooking of rice? Because it solved the two big remaining problems with rice cookers: 1) different varietals of rice have different cook times, and 2) cooks. Some rice cookers have different settings for white rice and for brown rice, for example. The Zojirushi fuzzy-logic product takes into account what type of rice it is cooking, and cooks it perfectly. As for cooks? A pot of rice requires only rice and water, and yet people occasionally get the proportions wrong. Provided the users aren’t too far off with their measurements, a fuzzy-logic rice cooker will simply adjust and render perfectly cooked rice despite the human error.

Right around the same time that fuzzy logic was applied to rice cookers, manufacturers also switched to induction heating, which can be controlled more precisely than heating coils. The combination of fuzzy logic and induction heating led to rice-cooking perfection. Or as close to it as we are going to get until the singularity gives us rice cookers with genius-level intelligence.

Today, the rice cooker is the only electronic kitchen gadget ever invented that tens of millions of cooks around the world use almost daily. There are fuzzy-logic rice cookers from Tatung, Tiger Corp., Panasonic, and others. Many are available for under US $100. Zojirushi, the pioneer, still commands prices well above $100 for most of its models.

Enter the member experience for exclusive contests and more.
The Conversation (0)

Video Friday: PoKeBo Cubes

Your weekly selection of awesome robot videos

2 min read
A young girl looks at a cluster of three simple robots facing each other on a table

Video Friday is your weekly selection of awesome robotics videos, collected by your friends at IEEE Spectrum robotics. We also post a weekly calendar of upcoming robotics events for the next few months. Please send us your events for inclusion.

RoboCup 2022: 11 July–17 July 2022, BANGKOK
IEEE CASE 2022: 20 August–24 August 2022, MEXICO CITY
CLAWAR 2022: 12 September–14 September 2022, AZORES, PORTUGAL
ANA Avatar XPRIZE Finals: 4 November–5 November 2022, LOS ANGELES
CoRL 2022: 14 December–18 December 2022, AUCKLAND, NEW ZEALAND

Enjoy today’s videos!

Keep Reading ↓Show less

The Day Business Suits Became In-App Purchases

Meta selling digital “fashion” isn’t a surprise, but the details come apart at the seams

4 min read
Meta Avatars wearing fashion from the Avatars Store.

Meta’s Avatars Store will sell virtual fashion from major labels.


Odds are you’ve added a piece to your wardrobe for a job interview or an important meeting. But what if that meeting happened in the metaverse? Would you spend money to upgrade your avatar?

Meta is hoping you’ll answer “yes.” CEO Mark Zuckerberg announced the company’s new Avatars Store, slated to go live within weeks, in an “avatar fashion show” with Instagram’s Eva Chen.

Keep Reading ↓Show less

Free On-Demand Webinars on Data Acquisition Boards and Their Applications

Explore the basics of digitizers, pulse detection, peer-to-peer streaming, and more

1 min read

Dive into the world of digitizers and explore how they can benefit your application. Explore the basics of digitizers, pulse detection, peer-to-peer streaming, and more. Whether you are a scientist, engineer, student or if you want to know more about Teledyne SP Devices deep knowledge base there is something for everyone. Register now for these free webinars!