Keywords

1 Introduction

The 50th CES (Consumer Electronics Show) was held in Las Vegas from January 4, 2017 to January 8, 2017. Every year CES brings many unexpected new technologies, which are applied to products and make people have many new experiences. These products have more excellent function, increasingly intelligent operation and simpler appearance. However, with these new experience, people need learn to use intelligent operation interfaces and master and manipulate these products. Only through the complex steps can excellent performance be shown. It is not difficult for young people to grasp the operation of these products, but it is not easy for the elderly and children. Some scholars such as John Clarkson and Simeon Keates put forward the concept of inclusive design, similar universal design and available design that product should meet the needs of all users [1], but these design concepts give no explicit solutions to specific problems. Therefore, this paper proposes that the multi interface design of household electrical appliances can solve the complicated operation interface of high-performance household electrical appliances.

2 Analysis of Design Demand for Existing Household Electrical Appliances

2.1 Existing Household Electrical Appliances Categories and Sample Selection

Electrical appliances which entered ordinary families in the twentieth century become increasingly rich after more than 100 years of development and have been an indispensable part of people’s lives. Up to now, there is no uniform standard for household appliances internationally. By convention, household electrical appliances are divided into large and small ones according to the size and white and black ones according to the performance and the color of traditional electrical appliances. The classification of household appliances are shown in Table 1.

Table 1. Classification of household appliances
Full size table

In order to more clearly understand the needs of home users for household appliances, we made a classified questionnaire survey on household appliances owned by the user’s home. Eight kinds of common household electrical appliances were surveyed, covering large and small household appliances and white and black ones. A total of 119 valid questionnaires were collected and the results are shown in Fig. 1.

Fig. 1.
figure 1

The survey data of household electrical appliance ownership

Full size image

According to the results of 119 valid questionnaires, it can be seen that the amount of household appliances family ownership is large currently and the ownership proportion from high to low is followed by refrigerator, TV set, cooker and washer. The human-computer interface of refrigerator is relatively simple and human-computer interaction is mainly to pick and place ingredients, hence TV set, washer and cooker were selected as the typical household electrical appliance categories for human-computer interface analysis in this study.

2.2 Analysis of Design Demand for Existing Household Electrical Appliances

There are two main design directions about the current household appliances. One direction is household electrical appliances, mainly for young people, which pursuit excellent performance and high-tech [2] and the operation interface is highly intelligent and complicated to operate and users need learn how to use. Samsung TV set and remote control are shown in in Fig. 2. The other direction is household electrical appliances for the elderly to use [3]. Skyworth TV set and remote control are shown in Fig. 3. Such appliances usually have low prices and are concerned about the physiological and psychological needs of the elderly. They have simple operation and simple functions and little attention is paid to their appliance performance and quality. These two mainstream design directions are the design based on a single population as the target user.

Fig. 2.
figure 2

(Source: Samsung Electronics Official Website)

Samsung QLED TV set and remote control

Full size image
Fig. 3.
figure 3

(Source: Pacific Computer Network)

Skyworth TV set and remote control

Full size image

According to the current mainstream design directions of household appliances, the demographic structure of Chinese family was investigated which is shown in Fig. 4.

Fig. 4.
figure 4

Survey data of Chinese family demographic structure

Full size image

According to the survey data of questionnaire, it can be seen that single age structure of the family accounts for only 16.81% of the total, which also includes the single age structure of young and middle-aged and the single age structure of the elderly. Nearly 100% of the market’s products are designed for less than 20% of households and it almost can not find household appliances specifically designed to meet the needs of families with multiple age groups. Therefore, the design of household appliances to meet the needs of families with multiple age groups will have a huge market space.

3 Analysis of Existing Household Electrical Appliances Interface

Human-computer interface, also known as the user interface or user interface, refers to the surface of the interaction when users interact with the product and the medium of interaction between user and product. Users input instruction to the machine through the interface and the machine receives the information, gives user feedback, and then runs according to the instructions to achieve product functionality. Household appliance interface is the bridge between household appliances and users. Good product interface design will give users a pleasant experience while bad interface design is a barrier between users and products, isolating the user’s product use demand and desires.

Early household electrical appliances have single function, the control interface is based on mechanical hard interface, which is usually buttons and knobs, and product feedback information is the sound, indicator, pressure and key stroke, etc. Household electrical appliances of this stage have simple operation and a high degree of availability. With the progress of science and technology, product function becomes more and more powerful and household appliances can achieve more subdivision function. At the same time, information technology is also applied to the design of household appliances and display screen and touch screen as important soft interfaces have become an indispensable part of modern household appliances. At this point, the difficulty of operation of household electrical appliances increases and the degree of usability decreases. Young and middle-aged users who are skilled at operating computers and smart phones in work and life can quickly grasp the control of soft interface. However, it is very difficult for the elderly and children in the family to master the operation of soft interface.

The comparative analysis of the usability of household appliance interface is shown in the Table 2.

Table 2. The comparative analysis of the usability of household appliance interface
Full size table

4 The Model of Multi Human-Computer Interface Household Appliances

It can be seen from Table 2 that when the function of household appliances becomes increasingly rich and powerful, the operation becomes more complex and adaptive user groups are getting less. In order to make household appliances better meet the needs of families with multiple age groups, solving the contradiction between high performance and complicated operation of household electrical appliance becomes a research topic urgently needed to solve the current design of household electrical appliances. In the premise of meeting the high performance, multi-interface design can be a good solution to this problem.

Processes of household appliance interface design and product design are similar and user-centric, relying on the needs of users to develop. Figure 5 is the household appliance interface design process.

Fig. 5.
figure 5

The household appliance interface design process

Full size image

4.1 Classification of User Groups

Design psychology expert Norman divided users into four categories “novice user, average user, expert user and casual user” [4]. Novice users cannot complete the use process of product relying on past experience when facing products and need to learn to achieve the average user level to complete the smooth operation of the product. Expert users are more familiar with the product and can skillfully operate the product, or even develop new use functions. Casual users do not often use the product for a variety of reasons, are not familiar with the product and can not successfully operate the product.

The Fig. 6 are the results of investigation on the TV set, washer and cooker family operators. According to the survey, it can be seen that the main use of groups of household electrical appliances are the young and middle-aged crowd, followed by the elderly, and children use less household appliances. Among them, the use of children in TV sets is similar to that of the elderly.

Fig. 6.
figure 6

The results of investigation on TV set, washer and cooker family operators

Full size image

According to the survey, home users can be classified into young people, some elderly people and children which together constitute the average user base, as shown in Fig. 7.

Fig. 7.
figure 7

The diagram of home user classification

Full size image

Each user group for the interface learning ability is shown in Fig. 8. Expert user who is the electric operation master in home users accepts the existing high-performance household appliance interface without any barrier. Average user can master the operation mode through learning and be skilled at operating usual electric appliances while novice user has difficulty in completely grasping the full operation of high-performance products even through learning, so novice user needs a more intuitive and simple operation interface. Casual user with weak operation ability in home users may be home visitors or users with poor learning ability in the family needs the most intuitive and clear interface. When the product interface does not constitute an obstacle for casual user and novice user, average user and expert user can quickly grasp the operational flow.

Fig. 8.
figure 8

The comparison diagram of home user operating capacities

Full size image

4.2 Function Analysis of Household Appliance

Researchers also divide users into ordinary user and quality user according to the user’s demand for product functionality. Ordinary users have no more requirements for the product, and as long as the product can reliably complete the basic use of functions and they can easily operate on it while quality users pursue more complete product experience and more abundant product functions [5]. Traditional household electrical appliances have no basic operational problems due to the single function and simple operation. Modern product interface problems result from function enhancements and performance improvements, and the analysis of functions can help us determine the selection of function interface.

Here, we call the main function and commonly used function of electrical appliances as basic functions, some functions which meet the user’s individual needs and occasionally used functions as quality functions, functions which are integrated with intelligent technology and can interact with users or are achieved relying on the network as intelligent functions. Table 3 is the analysis of the functions of three types of household electrical appliances.

Table 3. Comparative analysis of functions of household electrical appliances
Full size table

4.3 Multi-interface Design Solutions

Through the comparative analysis of existing products, it can be seen that the difficulty of the interface operation of high performance household appliances is mainly due to increased quality functions and intelligent operation, and complex hierarchical structure increases the difficulty of interface operation.

The soft interface of intelligent household appliances is difficult to operate and user experience is enhanced by hard interface design.

The intelligent degree of modern household appliances is getting higher and higher. According to the data from AVC, it can be seen that the penetration rate of smart TV, smart air-conditioning, refrigerator’s intelligence and washer’s intelligence has reached 79%, 21%, 10% and 16% respectively in the first half of 2016 [6]. Intelligence of household appliances becomes increasingly apparent and complex operating problems are also highlighted, in which the problem of TV control is particularly prominent.

With the development of intelligence, the traditional operation hard interface gradually disappears. The simple product design that enterprise pursues hides hard interface to the back of the product. Samsung TV set is shown in Fig. 9. Users do not know how to open the machine when facing such a high-tech product because no operation interface could be found in the front and side of the product. Casual user and novice user have to read a thick specification and learn to operate the product in order to know the location of hidden open key, which brings much discomfort to them. In view of this problem, setting up operation interface in the front of product should be taken into consideration, such as power key, volume adjustment keys, etc.

Fig. 9.
figure 9

(Source: Samsung Electronics Official Website)

The diagram of Samsung TV set and operation interface

Full size image

The increase of quality function leads to complex interface and the hidden quality function interface makes the product easy to operate.

From the multifunctional washer interface shown in Fig. 10, it can be seen that novice user does not know what to do and how to operate the product smoothly when confronted with such a complex interface, resulting in poor user experience. Functions can be classified for this problem. One is commonly used and basic functions which are intuitively arranged in the product surface through traditional hard interface and the other is less commonly used quality functions which are hidden through soft interface, so that the product interface not only is simple and clear, but also meets the demand of quality users for function.

Fig. 10.
figure 10

(Source: Samsung Electronics Official Website)

Samsung washer and interface instruction

Full size image

Through the study, it can be found that the most commonly used functions are basic function which is suitable for hard interface to realize product operation. The application of quality function is less and the combination of soft and hard interface can be used to control the product. Intelligent function is mainly for average user and expert user to choose the operation and there is no difficulty in the operation basically, so the design of soft interface as a focus and hard interface as a supplement can be adopted. Table 4 shows function and interface selection table for household appliances.

Table 4. Function and interface selection table for household appliances
Full size table

Feedback effect of touch screen product operation is not clear, user experience is poor and the host operation to select the traditional hard interface can enhance user experience.

Japanese designer Abe Ase proposed tactile experience design [7] and emphasized that user experience can be enhanced through the design of touch. Figure 11 is the application of intelligent touch screen to cooker and the product looks simple and beautiful. However, the interactive experience of cold and hard touch screen is not ideal because the user cannot experience tactile press feedback when pressing the screen during operation, and no touch-screen button border makes user fear of misoperation, which leads to poor user experience. In the tactile experience, traditional button or knob interfaces allow users a more intuitive understanding of machine feedback to instructions through the key stroke and rotation, at the same time, the traditional hard interface with clear edge reduces the probability of misoperation, which results in good user experience.

Fig. 11.
figure 11

(Source: Taobao)

Intelligent cooker operation interface

Full size image

Construction of multi interface design process for household appliances.

Through the above analysis, in the household appliance interface design, the first step is to distinguish among home users, and then product functions are divided into basic functional demand, quality functional demand and intelligent functional demand according to the needs of users. Basic functional demand is suitable for design of intuitive hard interface, so that product meets the operational needs of all users, and quality function and intelligent function adopt a combination of hard and soft interface design according to the specific situation. Figure 12 shows the flow chart of multi interface design of household appliances constructed through the study.

Fig. 12.
figure 12

The flow chart of multi interface design of household appliances

Full size image

5 Design Principle of Hard Interface for Multi Interface Household Electrical Appliances

Multi interface design of household electrical appliances includes hard interface design and soft interface design. Soft interface design which is mainly aimed at average user and expert user has been analyzed in more detail in a lot of research for quality users, and is not discussed here. In the construction of hard interface in multiple interfaces, casual user and novice user including the elderly and children need be taken into account. Therefore, the following principles should be paid attention to in the hard interface design.

5.1 Hard Interface Arranged in the Location that User Can Intuitively Perceive

We can simplify any product into a positive cube as shown in Fig. 13. The front of the product faces users and four sides around the front can also intuitively perceived by users, so master operation of hard interface should be arranged in the five side, allowing users perceiving operating position. The main control interface should be avoided arranging in the back of the product, which brings use disorder to novice user and casual user for the first time. Even average user and expert user may feel inconvenient in the operation because the manipulation position is not visible.

Fig. 13.
figure 13

Six surface chart of household appliances

Full size image

The front, top, bottom, left and right sides are all intuitively perceived by the user, and the hard interfaces can be arranged in these areas. In the selection of interface arrangement area, considering that the top and bottom areas may be constrained by user, product, or spatial dimensions, sometimes it is not suitable for arranging the interface in this area. In addition, most users are accustomed to right-handed operation, so the right side is more suitable for the arrangement of the user interface than the left side. Based on the above analysis, the product hard interface arrangement priority area table is shown in Table 5.

Table 5. The selection table of household appliance interface
Full size table

Figure 14 is the main control interface of Samsung household TV and picture A shows the original design interface that the main control buttons are located in the lower left corner of the TV. Users can not find the location of hard interface intuitively in the operation, which brings use of obstacles. In order to avoid operational obstacles, it is recommended that the main control interface is set on the front or right side of the TV set, such as the red area of picture B, so that the user interface is easy to find and convenient to operate.

Fig. 14.
figure 14

The location of Samsung TV main control button and the proposed location map (Color figure online)

Full size image

5.2 Simplification Principle of Hard Interface Function

The function of modern household electrical appliances is becoming increasingly abundant, and there are a lot of subdivision quality functions. For example, laundry procedure of washer includes standard washing, quick washing, strong washing, wool washing and so on. If all of these functions are displayed on the operating panel, too many choices can interfere with the user, hence basic functions, quality functions and intelligent functions of electrical appliances should be distinguished in the design of product hard interface. The basic function is realized through the hard interface design. When choosing the hard interface to control the product, the basic function quantity must be strictly controlled in order to effectively achieve the interface simplification and enhance user experience. At the same time, quality function and intelligent function are hidden in the soft interface, and the segmentation function of product can be realized effectively through the reasonable design of soft interface. The basic functions of three research products which can complete the control of product through hard interface design are summarized in Table 6.

Table 6. The selection table of household appliance interface
Full size table

Figure 15 is the comparison diagram of a simplified interface design and the original design. Figure A is the original design of Samsung washer interface and Figure B is the simplified hard interface of the washer operation panel.

Fig. 15.
figure 15

The comparison diagram of a simplified interface design and the original design

Full size image

5.3 Interface Feedback Principle of Human-Computer Interaction

After the user issues instructions to the product through interface, clear interactive feedback can allow users to determine that the machine has received instructions. The feedback of current household appliances on the market is good, but some household appliances use touch-screen or membrane keys to achieve human-computer interaction. Interfaces without pressure and stroke usually can not give a good tactile feedback to users, hence this feedback needs to be achieved and enhanced through design. Taking the physical and psychological characteristics of the elderly in the family into account, the feedback can be enhanced appropriately based on the original design, such as increasing the size of the screen and the key, adding the indicator light, expanding and extending the sound prompt and so on [8].

5.4 The Operating Instructions Can Be Added According to the Principle of Inclusive Design

The design goal of multi interface of household appliance products is aimed at meeting the needs of families with multiple age groups. Considering that novice user and casual user are not familiar with the operation process, increasing the operating instructions in the user interface can help users quickly grasp the operation process and thereby achieve convenient operation. The reference of product design method of Japanese household appliance manufacturers for the elderly, the operation process marked by number 1, 2, 3 allows users, even novice users or casual users, to see operating steps of the product at a glance, and complete the basic operation of the product quickly through instructions [9].

The diagram of washer interface marked by operating instruction numbers is shown in Fig. 16.

Fig. 16.
figure 16

The improvement plan of washer interface design

Full size image

6 Conclusion

With the development of science and technology, the quality of household appliances has been greatly improved and a single product can meet different user’s demand for personalized products. However, with the increase in segmentation function of electrical appliances, product operation becomes complicated. It is easy for average user and expert user in the family to grasp the complex operation through learning, while it is difficult for novice user and casual user in the family to grasp it through learning. In this case, designers should take full account of the differences in home users and give different interface solutions for different needs of users, so that the product can better meet the needs of families with multiple age groups.

Multi interface design not only improves the availability of products, but also can reduce user’s feeling of inferiority caused by difficult operation, so that all family members feel the joy of science and technology. Multi interface design of household appliances will also become an important direction of the future development of household appliances.