The Realization Of The Dressed-up Touchscreen With A Tactile Feedback

Electronic products using the touchscreen tend to increase. But it is difficult for elderly people who are unfamiliar with the touchscreen to operate the electronic products employing the touchscreen. In addition, cannot recognize the buttons on the touchscreen.In this study, we are aiming to realize a touchscreen that can give a sense of the button’s location and clickby a simple mechanism.The proposed touchscreen consists of a switch underneath the LCD module with a touchscreen and plates with an identification number at the top of the LCD module. When the touchscreen is pushed, the switch underneath the LCD module is also pressed. Thus, the user can get certain click feeling by the switch.For the plate put on the top of the LCD module, the places where icons are displayed in the touchscreen are hollowed out. Therefore, the edges around the buttons on the hollowed part give the user’s finger unevenness. That is, the position and boundaries of the icons can be recognized by the finger.In addition, since the type of the plate can be determined by the ID, we can provide a variety of button arrangement according to the plate used.To evaluate the click feeling and the operability, we develop a prototype system and measure the operation error and send out the questionnaires to some testees.The measured result shows that the miss ratio of key inputis less than that ofatraditional touchscreen. Also, the result of questionnaires indicates that our touchscreen is easier to manipulate than the conventional one.


Introduction
Electronic products using the touchscreen tend to increase.But it is difficult for personswho are unfamiliar with the touchscreenlike elderly or handicapped people to operate the electronic products employing the touchscreen [1] [2].What cannot recognize the buttons on the touchscreen is one of the significant problems to make the operation more difficult.
Therefore,the systems supporting the operation of the touchscreen by giving the finger the touch feelinghave beendeveloped in the past.
There arethree representativeresearches.First isdevices that are expressed sense pressing the touchscreen in vibration [3] [4].But,the vibration is not the same as the sense of the button switchwith a click feeling that we are accustomed to.Second puts amechanical switch under the touchscreen separated from LCD panel [5].Since it must locate a structure guiding the touchscreen around the LCD panel,the device becomes larger relatively.Also, the current touchscreen unified with the LCD panel cannot be used.Thirdoneputs the button sheet onto the touchscreen, whose buttons rise up from the surface [6].It attaches buttons of a special material in the button sheet.However,the position and the number of touch buttons are fixed andthe durability of the rising and recedingbutton pushed may be poor.
We aim to realize a touchscreen that can provide the position of the button and the click feeling by a simple mechanism, keeping the flexibility.The flexibility means that our touchscreen is able to adapt to any user interface when changing the button sheet.
In this paper, we outline the proposed system of the touchscreen and the field of application.Then, we develop a prototype system andevaluate in terms of operability and click feeling on this prototype system.

Touch panel system 2.1 System Overview
Fig. 1 shows a concept of the proposed touchscreen system.Mainly, the proposed touchscreen consists of a switch underneath the LCD panel and the plates with identification number at the top of the LCD panel.When a finger pushes the touchscreen, the switch underneath the LCD panel is also pressed.Thus, this touch panel givesthe user the click feeling that is the same as that of mechanical switch we are accustomed to.Since the touchscreen is only executed by pushing the switch, an incorrect input by just touching can be prevented easily.
For the plate put on the top of the LCD panel, the places where icons are displayed in the touchscreen are hollowed out.Therefore, the edges around the buttons on the hollowed part give the user's finger unevenness.That is, the position and boundaries of the icons can be recognized by the finger.The ID can be read by placing the plates on the reader, the system can determine the type of plate.Therefore, the proposed touchscreen can correspond to the various arrangement of the button.In addition, the plate can be used or not can be use depending on the application.Information such as the placement of the buttons on the screen hierarchy and each layer of the plate and defaultis stored ina database.The necessary information according to the plate switching and button pushing is selected from the database.

Application Areas
This touchscreen can be applied to a variety of electronic products.The followings show application examples.・A multi-remote controller with our touchscreen that can handle several electronic devices.・An electronicadvertisement board and a digital signageon the station and the street.・Vending machines, ATM, Voting system, Ticketingand so on.As mentioned above, the proposed touchscreencan be widely applied to electronic devices using a touchscreen.Thus weexpectthat elderly people canoperate the touch panel smoothly.We alsothink that it is accessible for visually impaired people tomerge the audio guide withthe proposed touchscreen.

Prototype system 3.1 Organization
In realization of the aiming touch panel,we have developed a prototype system in order to perform several preliminary experiments.
Fig. 2 shows a block diagram of the prototype.Fig. 3, Fig. 4 and Fig. 5 show the real machine.
The LCD module consists of the LCD with the 240x320 of 3.2 inch resistive type touchscreen,the LCD controller of SolomonSystechSSD1289and the AD converter for the touchscreen of SHENZHEN XPTEK TECHNOLOGY xpt2046.
This prototype usesthe plateID as RFID.The RFID reader is ID Innovations ID-12.The switches underneath the LCD module are push-button switches of OMRON B3F5000.
These three parts are connected to the microcomputer board of Strawberry Linux STBee that equipped with ST Micro's STM32 microcontroller.
Software to run on STM32calculates the X-Y axis of the finger sent from the AD converterattached toLCD module as shown in Fig. 6.Depending on the pressing of the switch,the microcomputer performs the processing corresponding to the default state and the current plate.

Fig.2. Block diagram 3.2 Basic Function
To realize a touch panel, the basic functions as follows have to be executed correctly.We havedeveloped a library that runs these basic functions in the C language.Fig. 7

Experimental Setup
We experimented to measure whether the prototype based on our proposal makes the touchscreen operation easier than the conventional touchscreen due to the tactile ofa click feeling and a position of the button.Therefore, we had some testees operate the conventional touchscreen and the proposed touchscreen on some case studies of key typing.Through this experiment, we measured the number of missed key inputs.In addition, questionnaires about usability were sent out.We prepared three patterns of button arrangements corresponding to three individual plates as case studies.If users place the plate with an ID on the reader, ID is read by RFID.Then, they are able to input some characters via the buttons that correspond to the plate ID.The sequence of the keys to be inputted is randomly displayed on the screen.
Input patterns are the followings: a) 8 characters randomly selected from A to H (Pattern 1) b) 8 characters randomly selected from a to Z with switching a capital letter and a small letter (Pattern 2) Pattern 1 and pattern 2 are shown in Fig. 8 and Fig. 9. Fig. 10 (a) and (b) show the experimental setup.The prototype and the conventional touchscreen display a random string of 8 characters.
Ten testees enter the string by the buttons displayed on the touchscreen.Then, we measure the correctness ratio.The calculation method of the correctness ratio is the following.
the correctness ratio ％ ＝ the number of times the user input the correct characters the number of times the user touched × 100 (1) Testees are as follows according to their ages.20s: five men, two women 50s:One woman 70s:One woman 80s:One man In addition, testees of the 80s and 70s performed only pattern 1 according to the circumstances of testees.Thus, Pattern 2 is performed in eight testees, except for the 70s and 80s.Further, we sent out a questionnaire on feeling of the prototype.The contents of the questionnaire are as follows.(a) Whether there is a click feeling in a prototype.(b)Whether users can identify a position and the boundaries of the button by the edge on the hollowed part.(c) Whether the prototype is easier to use than the conventional touchscreen.We had testees evaluate three items mentioned above at five levels.12 show the ratio of which the number of keys that are correctly inputted is divided by the total number of characters.Table 1 shows their average.Fig. 11 shows the correctness ratio of the prototype is clearly higher than that of the conventional touchscreen in the older testees than the 50s.Therefore, we think that the proposed touchscreen can be operated more smoothly than the conventional touchscreen for the elders.
Fig. 11(b) indicates that the correctness ratio of all testeeson the prototype became 100% after second time.Also, Fig. 12 shows that correctness ratio of all testees became 100% at the second time on the prototypeas well.This fact indicates that by using our proposal the operation of the touchscreen can be smoother in even 20s who are accustomed to the touchscreen.
Table .1 shows that the input mistake of the prototype is totally less than that of the conventional touchscreen.
Fig. 13 (a), (b),and (c) show the results of the questionnaires.The result also indicates qualitatively that the proposed touchscreen is desirable to operate the touchscreen compared with the conventional touchscreen.
Fig. 13 (a) shows that the testees of 70 % certainly sense a click feeling, and the rest strongly feels it.That is, all testees recognize the click feeling on our proposal.
Fig. 13 (b) demonstrates that the edge on the hollowed part of the plate can give the testees the button position actually.This is because all testees answer that they can recognize the boundaries and positions of the buttons.Consequently, as shown in Fig. 13 (c), it is also qualitatively confirmed that our proposal is actually desired compared with the conventional touchscreen.

Conclusion
This paper has proposed the dressed-up touchscreen with a tactile feedback.The experimental results have demonstrated that the proposed touchscreen is desirable to operate the touchscreen than the conventional touchscreen.As future work, we will perform an experiment to the more testees.Also, we will plant to develop actual system as shown in 2.2.

Fig. 1 .
Fig.1.Concept of the proposed system touch panel

Fig. 4 .Fig. 3 .
Fig.6.Processing flow (a) and (b) show the execution snapshots of the basic functions.Fig.7 (a) and (b) were run by different plate IDs.Then, the microcomputer distinguishes each ID number corresponding to them.(A)to(E) of Fig.7(a) and (b) show the followings.(A) Display the X-Y axis of the touched portion.(B) Display the plate ID. (C) Display the blue square after pressing the push-button switch.(D) Display the yellow square after touching on the LCD module.(E) Change the color of the square by the plate ID.

Fig
Fig.12.The correctness ratio of pattern2

Fig
Fig.13.Result of a questionnaire

Table 1 .
Comparison of the correctness ratio of the conventional touchscreen and the prototype