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Dishwashers (Panasonic Corporation)

As people spend more time at home due to the COVID-19 pandemic, the time taken for housework has increased.*1

There is data*1 that indicates the dishwasher is the most popular home appliance that consumers want to purchase in order to offset the increase in time taken for housework. However, in Japan, the penetration rate of dishwashers is still less than 30%. In this article, we asked Panasonic Corporation, a leader in the dishwasher market, about the background specific to Japan as well as their efforts to raise the penetration rate.

(Fig.1) Dishwashers
(Fig.1) Dishwashers

Hoping to free Japanese women from housework
(Impetus and recognized issues)

Panasonic continues to follow the mission statement set by their founder, Matsushita Konosuke, to "devote ourselves to the progress and development of society and the well-being of people through our business activities, thereby enhancing the quality of life throughout the world."

As part of their efforts to follow this mission statement, the company started to develop dishwashers that embody their founder's strong hope to free Japanese women from housework, launching the first dishwasher in Japan in 1960. Back then, the monochrome television, washing machine, and refrigerator were called the "Three Sacred Treasures," as they were what consumers wanted the most.

(Fig.2) The mission statement of Panasonic
(Fig.2) The mission statement of Panasonic

The dishwasher which Panasonic launched before any of their competitors was as big as a washing machine today.

Although the dishwasher was developed to reduce the burden of housework like other home appliances such as the vacuum cleaner and the washing machine, in contrast to its penetration rate of over 70% in Europe and the U.S., it did not spread quickly in Japan.

According to Panasonic, there are two reasons for this.

First, in Japanese residences, the kitchen is small, and there is no space for a dishwasher compared to Europe and the U.S. So a primary reason is that consumers want to buy one but lack the physical space to place it. Some data*2 shows a dishwasher penetration rate of around 35% for stand-alone houses, which have more space, but less than 10% in private rental housing.

Second, the dishwasher is not recognized to be a home necessity. The dishwasher is still considered to be a luxury, and consumers have doubts about the dishwasher's ability to wash dishes.

(Fig.3) As big as a washing machine
(Fig.3) As big as a washing machine

  • *2 Source: Penetration of Durable Goods, Consumption Trend Survey by the Cabinet Office (2020)

Pursuing size reduction for 60 years
(Details of the invention and design)

Panasonic has repeatedly improved its dishwashers to keep up with changes in housing conditions and lifestyles in Japan for over 60 years since launching its first model in 1960.

The dishwasher cleans dishes by jetting high-temperature, high-pressure water that is too hot for people to touch onto the dishes. For this reason, the dishwasher is said to clean dishes better than when washing by hand.

Size reduction is indispensable to realize a dishwasher that can be installed in Japanese kitchens. However, in a smaller dishwasher, one must stack dishes carefully because the size and amount of dishes cannot be changed. This makes it difficult for high-temperature, high-pressure water to reach all the dishes, which may leave some dirty.

Here, what plays an important role is the nozzles that jet high-temperature, high-pressure water.

A dishwasher has many nozzles. By improving the shapes of the nozzles, the angles of jet orifices, and other features, Panasonic has succeeded in realizing high-temperature, high-pressure water that reaches dishes in every corner of the dishwasher in order to get them sparkly clean even if they are stacked close together.

In addition, the company has adopted two racks to hold and wash more dishes and harnessed their ingenuity to support dishes having various shapes.

Adding various innovations such as these one by one, Panasonic has developed compact dishwashers that can be installed in Japanese kitchens. Their efforts have resulted in the slim dishwasher NP-TSK1, which is as thin as 29 cm but can hold the same number of dishes as its predecessor.

(Fig.4) A dishwasher has many nozzles
(Fig.4) A dishwasher has many nozzles

Surveying installation space in rental housing
(Travails until completion)

A longstanding challenge for product development is that only compact dishwashers can be installed in Japanese kitchens.

Therefore, Panasonic engineers visited customers who lived in rental housing in order to install dummy dishwashers to conduct a trial. They continued to survey the optimal size, operability, and comfort from the viewpoint of customers by not only checking whether the dummy dishwashers could be installed in the kitchens but also verifying whether or not they got in customers' way while cooking, whether they made customers feel pressured, and other aspects.

As a result, the engineers found that rental housing often has 30 cm to 40 cm of space for a dishwasher next to the kitchen sink and that the dishwasher must have a depth of no more than 29 cm.

In this way, the engineers visited rental housing, checked the situation of the kitchens, set a specific numeric goal for a readily usable size, and shared their findings with the engineering team.

(Fig.5) Any space for a dishwasher
(Fig.5) Any space for a dishwasher

Further reducing the size without compromising washing performance
(Travails until completion)

Size reduction made nozzle arrangement difficult

The dishwasher size needed to be reduced as much as possible while keeping it a rectangle to realize a depth of no more than 29 cm. Because the nozzles that jet water to wash dishes rotate, the engineering team tested nozzle arrangement, how to jet water, and other features over and over in order to ensure the nozzles smoothly rotated even in a slim rectangular dishwasher so that high-temperature, high-pressure water could reach every corner.

Ensuring high washing performance and quality

Even if the company realizes a slim dishwasher, it cannot be used comfortably if the dishwasher door gets in the way during use. So, to avoid getting in the way, the dishwasher door slides upward.

(Fig.6) The dishwasher door slides upward
(Fig.6) The dishwasher door slides upward

In addition, the dishwasher door has an important roleā€”to prevent leakage by sealing in high-temperature, high-pressure water.

Although high-pressure water is required to enhance washing performance, high pressure is associated with the possibility of water leakage. It is necessary to raise the sealability of the dishwasher door to prevent water leakage while continuing to ensure it is easy to open and close the door.

To satisfy both requirements, the company devised a nozzle structure in which high-temperature, high-pressure water does not hit the gap between the door and the main unit.

The company also improved the dishwasher's overall performance so that each function smoothly interacts with the others because changing the nozzle structure affects the other functions. By consolidating many different technologies in this way, Panasonic ultimately realized the slim dishwasher NP-TSK1, which combines high washing performance with great usability.

The proprietary know-how that Panasonic has accumulated over more than 60 years of dishwasher development has been applied to the NP-TSK1.

Expanding the market while trying to improve by learning from competitors
(How industrial property rights contributed to the invention)

Panasonic hopes that many companies will enter the dishwasher market to raise the penetration rate of dishwashers in Japan. This is because if each company tries to improve by learning from others and sells attractive products, the market will expand and needs will increase, which will, in turn, motivate more customers to use dishwashers. Panasonic hopes to lead the market rather than to monopolize it.

Attempting to expand the dishwasher market with its competitors, Panasonic applies for about 10 patents each time it launches a new dishwasher model based on a strategy of safeguarding their strengths as intellectual property under the slogan of "Secure Intellectual Property Before Starting a Business."

The patent applications are centered around the three strengths of Panasonic dishwashers: washing performance realized by nozzles and other features; size and other elements to facilitate installation; and the usability of the racks, door, and other components. Thus far, no counterfeit goods have appeared, which is due in part to the effects of the company's strategy of protecting differentiating features as intellectual property.

Creating free time while protecting the global environment
(Effects of the invention)

The social benefits of the dishwasher are not limited to freeing people from cumbersome housework and securing free time.

As awareness of cleanliness is high due to recent changes in society, Panasonic dishwashers meet needs for sterilization in addition to dishwashing.

Moreover, because the dishwasher circulates the water it uses as well as supports bulk washing, it uses less water than when people wash dishes by hand. The slim dishwasher is said to save water by about one-sixth.*3

There is data that indicates that the penetration rate of dishwashers is higher in western Japan than in other regions of the country. This is thought to be because western Japan used to frequently suffer from water shortages, leading to the spread of the dishwasher, which can reduce water use.

Panasonic plans to spread dishwashers to contribute to the achievement of the SDGs and the environment, continuing to widely raise awareness that the use of a dishwasher saves water.

Hoping that the dishwasher will become an everyday home appliance

At the end, we asked Panasonic about their vision for dishwashers in Japan.

"We hope that every household will have its own dishwasher. Imagine a desktop dishwasher replacing your plate rack. When you put dishes in the dishwasher after a meal, they are cleaned before you know it. We hope that many families realize this convenience and come to use dishwashers daily."

[Last updated 4 July 2022]


General Affairs Division,

Japan Patent Office