Touch panel and electronic device including the same

A touch panel and an electronic device including the same are provided. The touch panel includes a first substrate, a second substrate, an electro-rheological fluid, a sensor, and a controller. The second substrate is spaced apart from the first substrate by a gap and includes a touch surface. The electro-rheological fluid is filled in a gap between the first substrate and the second substrate. The sensor senses an input on the touch surface and determines an input location at which the input occurs, and the controller varies a viscosity of the electro-rheological fluid in a location corresponding to a peripheral region of the input location.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No. 10-2010-1443, filed on Jan. 7, 2010, the entire disclosure of which is herein incorporated by reference for all purposes.

BACKGROUND

Apparatuses and devices consistent with the following description relate to a user input device, and more particularly, to a touch panel and an electronic device including the same.

2. Description of the Related Art

A touch panel is one example of an user input device used to determine an input signal from a user and a position on a touch panel by sensing contact by the user thereon. A user may input data or signals to a touch panel by contacting or pressing the touch panel with his or her finger, a stylus pen or the like. Recently, a touch panel has been developed which can process continuous inputs or multi-touch inputs, such as a flick, a drag, a scroll, a pinch, a tap-and-slide and so on, wherein the terms continuous input and multi-touch input denote an input that is conducted when a user continually contacts or presses a user touch surface of the touch panel.

A touch panel may be implemented as a touch pad which is used as a substitute for a mouse for a laptop computer, a netbook and the like, or the touch panel may substitute for an input switch of an electronic device. Also, the touch panel may be used in association with a display. A touch panel which is mounted on the screen of a display, such as Liquid Crystal Display (LCD), Plasma Display Panel (PDP), Cathode Ray Tube (CRT) and the like, is called a “touch screen”. A touch panel may be integrated with a display to configure the screen of the display or may be attached additionally on the screen of the display.

The touch panel can be substituted for a user input device such as a keyboard and allow simple manipulations. Moreover, the touch panel can provide users with various types of buttons according to the types of applications to be executed or stages of the executed application. Accordingly, a touch panel, specifically, a touch screen, has been widely used as an input device for electronic equipment, such as a mobile phone, a Personal Digital Assistant (PDA), a Portable Multimedia Player (PMP), a digital camera, a portable games, an MP3 player, etc., as well as an Automated Teller Machine (ATM), an information trader, a ticket vending machine, etc.

A touch panel can be classified into a resistive type, a capacitive type, a saw type, an infrared type, etc., according to the methods of sensing an input of the user. A capacitive type touch panel determines whether a user presses the touch panel and the position of the user's press by measuring variations in capacitance due to contact or pressure. However, the capacitive type touch panel does not provide a user with a sense of input, that is, a feeling of recognition that a user gets upon inputting. In order to overcome this disadvantage, a method of installing a vibration motor below a touch panel has been proposed. The method offers users a sense of input by vibrating the whole touch panel using the vibration motor when a press by the user is sensed. However, the method fails to offer a sense of input when a continuous input, such as a multi-touch input, is sensed, and also users cannot check if the continuous input is being processed correctly unless they continue to watch the touch screen or display.

SUMMARY

One or more embodiments relate to a touch panel that allows a user to experience, when conducting a continuous input, a sense of input through his or her tactile sensation, and an electronic device including the touch panel.

One or more embodiments also relate to a touch panel that allows a user to recognize, when conducting a continuous input, a location at which the continuous input operation has to be terminated, or an existence of any objects or any window border on a traveling path of the continuous input through his or her tactile sensation, and an electronic device including the touch panel.

According to an aspect of an embodiment, there is provided a touch panel that includes a first substrate, a second substrate, an electro-rheological fluid, a sensor, and a controller. The second substrate is spaced apart from the first substrate by a gap and includes a touch surface. The electro-rheological fluid is filled in a gap between the first substrate and the second substrate. The sensor senses an input on the touch surface and determines an input location at which the input occurs, and the controller varies a viscosity of the electro-rheological fluid in a location corresponding to a peripheral region of the input location.

According to an aspect of an embodiment, there is provided a touch panel including a first substrate, a second substrate, a plurality of driving electrodes, an electro-rheological fluid, and a controller. The second substrate is spaced a apart from the first substrate by a gap, the second substrate comprising a touch surface. The plurality of driving electrode arrays include driving electrodes that are arranged on the first substrate and the second substrate such that the driving electrodes form driving electrode pairs, each of the driving electrode pairs including a driving electrode on the first substrate and a corresponding driving electrode on the second substrate and each of the driving electrode pairs is configured to induce an electrical field locally between the first substrate and the second substrate upon application of a driving voltage. The electro-rheological fluid is filled in the gap between the first substrate and the second substrate, and a viscosity of the electro-rheological fluid is changed by an electrical field induced by the driving electrode pairs. The controller applies, when a continuous input from a user is sensed on the touch surface, a driving voltage pattern to driving electrode pairs in a location corresponding to at least one peripheral region of a latest input location among locations at which the continuous input is sensed.

According to an aspect of an embodiment, there is provided an electronic device that includes a touch panel according to one of the touch panels described above.

DETAILED DESCRIPTION

A touch panel according to embodiments that will be described below is a kind of user input device for electronic equipment to execute an instruction by sensing a continuous contact or pressure from a user on a user touch surface. The instruction may be predetermined. That is, a user may input a desired instruction to electronic equipment with a touch panel by continuing to contact or press a user touch surface of the touch panel. Such a continuous input or a multi-touch input denotes that an input location (that is, a location on the user touch surface which the user contacts) continues to move while the input is maintained. That is, a continuous input is an input of which the location moves along a path for a certain time interval, and the continuous input is different from inputs generated by repeatedly tapping a certain area on a touch panel, continuing to contact or press a certain area on a touch panel for a predetermined time period, or discontinuously contacting or pressing a certain area on a touch panel, etc. The path may be predetermined, and the certain time may also be predetermined. Also, it will be apparent to those skilled in the art that the traveling paths, distances and velocities of continuous inputs, what instructions such continuous inputs function as, etc. are not concerned with the current embodiments and do not limit the embodiments.

A touch panel may be mounted as a user input device onto various kinds of electronic devices. Specifically, a touch panel may be utilized as an input device for home/office appliances, as well as a touch pad for a notebook, a netbook or the like. Also, a touch panel may be implemented as a touch screen that is mounted onto a display of an electronic device. For example, the touch panel may be implemented as a touch screen of an electronic device, such as a mobile phone, a personal data assistant (PDA), a portable media player (PMP), an E-book terminal, a portable computer, a Automated Teller Machine (ATM), an information searcher, a ticket vending machine, etc.

A touch panel according to an exemplary embodiment provides a user who conducts a continuous input with a tactile sensation against a contact surface. That is, a user who moves an input location while contacting or pressing a touch panel may feel tactile variations against the contact surface of the touch panel along with the movement of the input location. For example, a user may feel, when moving an input location on a touch panel, tactile variations by sensing an increase or decrease in rigidity of the screen against the contact surface of the touch panel. In the current embodiment, a touch panel is utilized having Electro-Rheological (ER) fluid interposed in between upper and lower substrates thereof in order to increase or decrease the rigidity of the screen against a contact surface of the touch panel. In the touch panel, the viscosity of electro-rheological fluid below the peripheral regions of a current input location (or a sensed latest input location) varies as the input location moves, which will be described later.

FIG. 1is a block diagram of an exemplary touch panel100, FIG.2is an exploded, perspective view showing a configuration of a touch panel body110of the touch panel100illustrated inFIG. 1, andFIG. 3is a cross-sectional view of the touch panel body110cut along a line III-III′ ofFIG. 2.

Referring toFIG. 1, the touch panel100includes a touch panel body110, a sensing unit120and a controller130. The touch panel body110is a physical structure included in the touch panel100. The sensing unit120and controller130may be electrical circuits and/or a combination of hardware and software, or only software which sense any input to the touch panel body110to control driving of the touch panel body110. Accordingly, the term “touch panel” used in this specification may indicate only the touch panel body110in a narrow sense, but also may indicate the entire touch panel100including all of the touch panel body110, the sensing unit120and the controller130in a broad sense.

InFIG. 1, the sensing unit120and controller130are shown to be divided for logical classification according to their functions, however they may be integrated into a single unit or implemented as separate devices. The logical function classification between the sensing unit120and controller130is for convenience of description. In other words, a single integrated component may perform all functions of the sensing unit120and controller130, or some functions of one (for example, the sensing unit120) of the sensing unit120and controller130may be performed by the other one (for example, the controller130). Hereinafter, a configuration of the touch panel body110will be described in detail with reference toFIGS. 2 and 3.

Referring toFIGS. 2 and 3, the touch panel body110includes a pair of substrates (that is, a lower substrate111and a upper substrate112), electro-rheological fluid113that is filled and sealed in the gap between the lower substrate111and the upper substrate112, and driving electrode arrays in which driving electrodes are arranged in pairs.

The lower substrate111, which is a base substrate of the touch panel body110, acts as one side of a container for filling the electro-rheological fluid130in the touch panel body110. When the corresponding touch panel100(seeFIG. 1) is implemented as a touch screen of an electronic device, the lower substrate111may be a display plane of the electronic device or a substrate attached additionally onto the display plane. The lower substrate111may be configured so as not to be deformed when a certain attraction force or repulsive force is applied between the lower substrate111and the upper substrate112. That is, the lower substrate111may be made of a rigid or hard material. For example, the lower substrate111may be made of transparent glass. However, there are situations in which it is advantageous for the lower substrate111to be made of a material that not a hard material. For example, if the touch panel body110is attached on a hard display, the lower substrate111may be made of a transparent polymer film.

The upper surface of the upper substrate112is a user touch surface which a user contacts to input a signal. The upper substrate112may be deformed when predetermined force is applied thereto. For example, the upper substrate112may be deformed when a user contacts or presses the user touch surface with a finger, a stylus pen, etc. For such deformation, the upper substrate112may be made of a transparent, deformable polymer film or the like. The type of polymer usable for the upper substrate112is not limited. The upper substrate112is spaced a predetermined distance apart from the lower substrate111and accordingly a gap having a predetermined thickness is formed between the upper and lower substrates112and111. The thickness of the gap may be set appropriately in consideration of a driving voltage, the width of the touch panel body110, a cross-sectional area of each driving electrode pair114, etc.

The electro-rheological fluid113is disposed in the gap between the lower and upper substrates111and112. The electro-rheological fluid113may be sealed with sealant116may be applied along facing edge portions of one or both of the upper and lower substrates112and111. The electro-rheological fluid113is a suspension in which fine particles113bare dispersed in electro-insulative fluid113a. The viscosity of the electro-rheological fluid113can change by a factor of about 100,000 as a maximum when an electric field is applied thereto, and since such variation in viscosity is reversible, the viscosity returns to its original level when the electronic field disappears.

The electro-rheological fluid113may be a transparent liquid such as, for example, silicon oil, kerosene mineral oil, olefin (PCBs), or the like. However, the electro-rheological fluid113may be any other material that possesses similar properties of low viscosity change with changing temperature, high flash point, low freezing point, etc. and for which the viscosity changes as a function of the electric field applied thereto. The particles113bincluded in the electro-rheological fluid113may be very fine, transparent particles having a size of maximally about 50 μm. The particles113bmay be polymers, such as aluminosilicate, polyaniline, polypyrrole, or fullerene, or any other kind of insulative materials, such as ceramics or the like. Non-transparent ERF may also be used in some applications.

Also, spacers115may be provided in a dispersed manner in the gap between the upper and lower substrates112and111. The spacers115are elastic elements made of small, transparent particles whose size is less than about several tens of micrometers and are randomly distributed in the electro-rheological fluid113. The spacers115shown inFIG. 2are exaggerated in size, and the arrangement of the spacers115shown as if they are dispersed at regular intervals is also exemplary for convenience of description, and in reality the spacers115are more likely to be randomly dispersed. Materials used to form the spacers115are not limited, and for example, the spacers115may be made of elastomer. The spacers115are used to provide the upper substrate112with restoring force and to support the upper substrate112structurally. That is, the spacers operate as elastic elements between the upper and lower substrate, and allow the substrates to recover to the original film shape in a very short time after a click operation, which will be described later. The spacers are advantageously spaced throughout the touch panel, but other types of distribution patterns may be used as long as the spacers may provide the restoring force and structural support. As discussed above, the distribution may also be random. For example, at the edges of the touch panel, the film tension is stronger than that of the center portion. Thus, it may be possible to use fewer spacers in the edge regions. That is, the spacer distribution may also vary depending on the location within the touch panel.

FIG. 4is a graph showing a relationship between a driving voltage to be applied to the driving electrode pairs114and viscosity of the electro-rheological fluid113. A shear rate generated when the touch panel100is driven may be in the range of about 5 (l/s) to about 3000 (l/s). InFIG. 4, this range is denoted by “fluid flow region.”FIG. 4shows variations in viscosity of two kinds of electro-rheological fluids (one (ER(1)) is a widely commercialized electro-rheological fluid and the other (ER(2)) is a so-called “Pani-Clay 15%”, however, these are only exemplary) when a driving voltage of 1 kV/mm is applied to the driving electrode pairs114(that is, when a driving voltage of 1 kV is applied to the driving electrode pairs114, wherein in each electrode pair the driving electrodes are spaced a distance of 1 mm apart from each other), and when the driving voltage is no longer applied to the driving electrode pairs114(0 Kv/mm). It can be seen inFIG. 4that application of driving voltage to the driving electrode pairs114increases the viscosity of the electro-rheological fluid113compared to when no driving voltage is applied thereto. Specifically, at a shear rate of 100 (1/s), a viscosity of the electro-rheological fluid113when applying a driving voltage is several tens or hundreds higher than that of the electro-rheological fluid113when applying no driving voltage for both fluids (ER(1)) and (ER(2)).

Also, it can be seen inFIG. 4that applying a different level of a driving voltage to the driving electrode pairs114makes the viscosity of the electro-rheological fluid113vary. This is because the viscosity of the electro-rheological fluid113is proportional to the driving voltage. Furthermore, an increase in viscosity of the electro-rheological fluid113increases shear stress. Hence, a user may have, when contacting or pressing the electro-rheological fluid113with high viscosity, great repulsive force from the electro-rheological fluid113. Due to this property of the touch panel100, the user may be made to experience various tactile sensations when applying a pressing force to the touch panel100.

The driving electrode pairs114are arranged on the lower and upper substrates111and112such that driving electrodes disposed on the lower substrate111are paired with those disposed on the upper substrate112. As illustrated in an area I ofFIG. 3, when a bias voltage (that is, a driving voltage) is applied to predetermined driving electrode pairs114, an electrical field is generated locally in the gap between the upper and lower substrates112and111where the driving electrode pairs114are positioned. As a result, in the I area, the viscosity of electro-rheological fluid113is increased. Meanwhile, in areas II ofFIG. 3, since no bias voltage is applied to the corresponding driving electrode pairs114, no electrical field is generated in the gap between the upper and lower substrates112and111where the driving electrode pairs114are positioned, and accordingly, in the II areas, the viscosity of electro-rheological fluid113does not vary. It is noted thatFIG. 3shows a single top electrode114band a plurality of bottom electrodes114awhen viewed from the side view (also seeFIG. 2). However, this arrangement is only exemplary. It is also possible to provide an M×N array of electrodes on both the top and bottom, such that each individual pair of electrodes (top and bottom) is separately addressable and controllable (seeFIG. 10).

The driving electrode pairs114may be arranged in the form of an array over the entire touch panel body110or arranged in the form of a matrix. In the case of arranging the driving electrode pairs114in the form of an array, a driving voltage may be applied to individual combinations of the driving electrode pairs114in order to supply the driving voltage only to selected driving electrode pairs. In addition, varying a combination of the driving electrode pairs114to which a driving voltage is to be applied or changing a driving voltage that is to be applied to the driving electrode pairs114may provide a user who conducts a continuous input with various tactile sensations, which will be described later.

FIG. 2shows an example of driving electrodes that are arranged in the form of a matrix, wherein a plurality of lower electrode patterns114aare arranged in parallel on the upper surface of the lower substrate111and a plurality of upper electrode patterns114bare arranged in parallel on the lower surface of the upper substrate112. The lower electrode patterns114aextend in a first direction and the upper electrode patterns114bextend in a second direction perpendicular to the first direction. Accordingly, at intersections of the lower and upper electrode patterns114aand114b, driving electrode pairs114are defined which are arranged in the form of an array throughout the entire area of the touch panel body110. Unlike this, upper and lower electrodes that are each formed as a dot may be arranged in an array over the entire surface of the upper and lower substrates112and111. In this case, the upper and lower driving electrodes may each be an active device allowing switching.

The driving voltage may be a power source which drives the touch panel100to vary the viscosity of the electro-rheological fluid113. The driving voltage may be supplied from a power supply of an electronic device with the touch panel100. The locations of driving electrode pairs114to which the driving voltage is to be applied and/or the level of the driving voltage are controlled by the controller130(seeFIG. 1) of the touch panel100. In the example illustrated inFIG. 3, a driving voltage is applied only to driving electrode pairs disposed in the I area whereas no driving voltage is applied to driving electrode pairs disposed in the II areas. A method of applying a driving voltage only to specific driving electrode pairs and adjusting a driving voltage that is to be applied to driving electrode pairs has little direct relation to the technical feature of the current embodiment and accordingly, detailed descriptions thereof will be omitted.

The touch panel100described above may be configured to generate input buttons on the user touch surface of the touch panel100and offer, when a user presses one of the input buttons without conducting a continuous input, the user with a clicking sensation similar to that felt when pressing a mechanical button. For example, by appropriately selecting areas (or combinations of driving electrode pairs114) to which a driving voltage is to be applied and applying a driving voltage only to the selected areas, input buttons may be defined in a certain form on the user touch surface so that a user may recognize areas (that is, areas of driving electrode pairs to which a driving voltage is applied, like the I area ofFIG. 3) with high viscosity of electro-rheological fluid113differently from areas (that is, areas of driving electrode pairs to which no driving voltage is applied, like the II areas of inFIG. 3) with low viscosity of electro-rheological fluid113. The certain form may be predetermined. Thereafter, when a user's input to a certain input button is sensed, the applied driving voltage is released if a time period for which the user's input is maintained exceeds a threshold time, thereby providing the user with a clicking sensation. This method of defining input buttons and offering a clicking sensation has been described in detail in U.S. application Ser. No. 12/780,996, filed on May 17, 2009, by the present applicant, entitled “Touch Panel and Electronic Device Including the Same”, and accordingly detailed descriptions therefore will be omitted herein. The disclosure of U.S. application Ser. No. 12/780,996, filed on May 17, 2009, and titled “Touch Panel and Electronic Device Including the Same” is herein incorporated by reference in its entirety for all purposes with this specification.

Referring again toFIG. 1, the sensing unit120determines whether a user's input to the touch panel100occurs and calculates, when a user's input is sensed, an input location where the user's input occurs. A method in which the sensing unit120detects a user's input is not limited. For example, the sensing unit120may sense a user's input and the input location by detecting a change in capacitance at a certain location on a user touch surface of the upper substrate112(seeFIG. 2), caused by the user's contact to the location. Information regarding the input location calculated by the sensing unit120is output to the controller130.

The controller130operates to vary the viscosity of electro-rheological fluid113below at least one peripheral region of the input location perceived based on the input location information. However, the viscosity of electro-rheological fluid113below other regions than the peripheral region of the input location may also vary. For example, it is also possible to vary the viscosity of electro-rheological fluid113below all regions excluding the current input location.

The viscosity of electro-rheological fluid113may vary depending on the intensity of an electric field applied thereto (seeFIG. 4). The controller130may vary the viscosity of electro-rheological fluid130by controlling a driving voltage to be applied to various driving electrode pairs114. The controller130may select locations (for example, the area I ofFIG. 3) corresponding to driving electrode pairs to which a driving voltage is to be applied, to control the locations at which the viscosity of the electro-rheological fluid113will be varied. The driving voltage may be controlled based on absolute criteria or controlled relative to the previously applied driving voltage.

The touch panel100may provide various tactile sensations to a user who conducts a continuous input such as sliding or tracing motion against the user touch surface. For this, the controller130may determine whether a current input is a continuous input based on input locations calculated by the sensing unit120. For example, when input coordinates sensed by the sensing unit120continue to vary over time, the controller130may consider the corresponding input as a continuous input. The time may be a predetermined time. However, the current embodiment is not limited to this example. For example, it is also possible that the sensing unit120determines whether an input from a user is a continuous input, and transfers, when determining that the input is a continuous input, the result of the determination result to the controller130along with information regarding input locations.

A continuous input is an input whose input location continues to vary over a certain time period, and the traveling path of a continuous input or the type of an instruction that will be executed by such a continuous input is not limited. For example, the traveling path of a continuous input may be in a horizontal direction, in a vertical direction, in a diagonal direction, in a zigzag direction, in an out and back manner, etc. Also, when an input operation such as a “pinch” operation using two fingers at once is conducted or when an input operation is combined with another operation such as a “tapping” operation, the input operation may be considered as a continuous input if the input location varies over time. Also, other than the case in which a continuous input is recognized as a predetermined instruction through a predetermined gesture, there is the case where a continuous input is recognized as a predetermined instruction in association with a displayed screen. For example, dragging & dropping one (for example, a file) of displayed objects, moving a scroll bar up and down and/or left and right, moving a playing time adjusting bar or a volume adjusting bar up and down and/or left and right, etc. may be examples of continuous inputs.

When it is determined that a continuous input occurs, the controller130controls the viscosity of the electro-rheological fluid113. In more detail, the controller130operates to locally vary the viscosity of electro-rheological fluid below peripheral regions of a current input location, that is, the latest input location among input locations at which the continuous input occurs. The “peripheral regions of the latest input location” need not be limited to peripheral regions in a predicted traveling direction (for example, a direction in which the continuous input has headed to reach the latest input location) of the continuous input. This is because the traveling path of a continuous input may arbitrarily be varied by a user.

Accordingly, the “peripheral regions of the latest input location” may be regions adjacent in all directions to the latest input location, as illustrated inFIG. 5. When the path of a continuous input is limited to a certain straight line section, for example, in association with a display screen, like a scroll bar, a playing time adjusting bar or a volume adjusting bar, as illustrated inFIG. 5B, the “peripheral regions of the latest input location” may be regions adjacent in the front and back directions to the latest input location. That is, the “peripheral regions of the latest input location” may be regions adjacent to the current input position along the scroll bar, the playing time adjusting bar, the volume adjusting bar, etc. For example, inFIG. 5B, the regions adjacent to the box having the circle therein are varied in the horizontal direction in the figure. In order to locally vary the viscosity of electro-rheological fluid113below the peripheral regions of the latest input location, the controller130may control the locations of driving electrode pairs to which a driving voltage is to be applied among the arrays of driving electrode pairs or may control a driving voltage that is to be applied to the corresponding driving electrode pairs, which has been described above.

If a driving voltage with a different level from a driving voltage being applied to the latest or current input location is applied to driving electrode pairs corresponding to the peripheral regions of the latest or current input location, the user who conducts the continuous input may have a different tactile sensation (for example, a different strength of repulsive force) over time. For this, a driving voltage with a level that is comparable to the driving voltage being applied to the latest input location may be applied to the peripheral regions of the latest input location. In this case, the driving voltage may be applied only during a time period for which the input from the user is determined to be a continuous input or only during a time period for which the input location continues to vary. During a time period in which the continuous input is maintained, the driving voltage with the level comparable to the driving voltage being applied to the latest input location is continually applied to the peripheral regions of the latest input location.

FIGS. 6A through 6Dare graphs showing exemplary driving voltage patterns that are to be applied to the peripheral regions of the latest input location. InFIGS. 6A through 6D, the vertical axis represents a level of a driving voltage that is applied to the peripheral regions of the latest input location with respect to a traveling distance of a continuous input. As the viscosity of electro-rheological fluid is proportional to a driving voltage, an increase or decrease of a driving voltage increases or decreases the viscosity of electro-rheological fluid. Also, the increase or decrease in viscosity of electro-rheological fluid increases or decrease a rigid sensation that a user can feel. Since the input location of a continuous input varies over time, the locations of the peripheral regions also vary over time. That is, as a current input location moves, the peripheral regions of the current input location also move along the traveling path of the continuous input.

According to the driving voltage pattern illustrated inFIG. 6A, a driving voltage increases in proportion to the traveling distance of a continuous input. The driving voltage may increase linearly (as denoted by a straight line) or may increase stepwise (as denoted by a stepped dotted line). The level of a driving voltage to be initially applied and the slope of the increasing driving voltage are not limited. The slope of the increasing driving voltage does not need to be constant and may vary depending on the traveling distance of the continuous input or the content of a display screen (for example, existence of objects, window borders, etc.). An increase in the driving voltage increases the viscosity of electro-rheological fluid below the peripheral regions of the current input location and accordingly a rigid sensation that a user can feel also increases.

Referring toFIG. 6B, a driving voltage decreases as the traveling distance of a continuous input increases. Here, the driving voltage may decrease linearly (a straight line) or stepwise (a dotted line). Likewise, the level of a driving voltage to be initially applied and the slope of the decreasing driving voltage are not limited. Also, the slope of the increasing driving voltage does not need to be constant and may vary depending on the traveling distance of the continuous input or the content of a display screen (for example, existence of objects, window borders, etc.). Since the increase or decrease of the driving voltage increases or decreases the viscosity of electro-rheological fluid below the peripheral regions of the current input location, a user may experience great or small repulsive force correspondingly.

Referring toFIG. 6C, a driving voltage rises and falls alternately along with a traveling distance of a continuous input. Here, the driving voltage may rise and fall continuously like a sine wave or discontinuously like a pulse wave. The amplitude or period of such a sine wave or pulse wave may be constant regardless of or vary depending on the traveling distance of the continuous input. The alternate rising and falling of the driving voltage alternately increases and decreases the viscosity of electro-rheological fluid below the peripheral regions of a current input location, so that a user may experience alternately great and small repulsive force correspondingly.

Referring toFIG. 6D, a driving voltage is maintained constant regardless of a traveling distance of a continuous input. The driving voltage may be set as a minimum voltage (MIN) or a maximum voltage (MAX) at which a touch panel can operate normally, or as an arbitrary voltage between the minimum driving voltage (MIN) and the maximum driving voltage (MAX). As such, in the case of maintaining a driving voltage constant, the viscosity of electro-rheological fluid is also maintained constant, so that a user may experience constant repulsive force while conducting the continuous input.

The driving voltage patterns shown inFIGS. 6A through 6Dmay be individually applied for a continuous input, or two or more of the driving voltage patterns may be combined and applied for a continuous input. The magnitude, increasing or decreasing slope, period and/or amplitude of each driving voltage pattern may vary. Also, a driving voltage pattern may be pre-set for an electronic device with a touch panel or set arbitrarily by a user who conducts a predetermined continuous input. In the latter case, it will be apparent to those skilled in the art that a driving voltage pattern may be selected depending on the type of a continuous input and/or a kind of an instruction that is to be executed by a continuous input.

By utilizing the touch panel100described above, various tactile sensations or repulsive force variations according to the types of continuous inputs may be provided to users. Particularly, if the touch panel100is implemented as a touch screen, various tactile sensations may be provided to a user in consideration of kinds of objects displayed on a display of the touch screen, the existence or absence of window borders, or the kinds of instructions that are to be executed through continuous inputs, etc. Through such various tactile sensations, the user may recognize whether continuous input is being conducted correctly only by tactile sensation without having to view a displayed screen. Hereinafter, an example of offering various tactile sensations in regard to the types of continuous inputs will be described in detail.

FIG. 7Aillustrates an exemplary continuous input to drag and drop a specific object, andFIG. 7Bshows an exemplary driving voltage pattern that is applied when the continuous input illustrated inFIG. 7Ais conducted. Referring toFIG. 7A, a user inputs an instruction for dragging and dropping an icon (for example, a certain file) displayed on a screen from its initial location210to a target location220. Referring toFIG. 7B, while the user drags the icon (230), a driving voltage that is applied to the peripheral regions of a current input location (that is, the latest input location) is in a pulse wave form. When a driving voltage is applied in a pulse wave form, the viscosity of electro-rheological fluid below the peripheral regions alternately increases and decreases along with the movement of the current input location. As a result, the user who slides a user touch surface of the screen with his or her finger may experience an alternate increase and decrease in rigidity of the screen.

Applying a driving voltage in the pulse wave form may be repeated until the icon210reaches the target location220. Alternatively, as illustrated inFIGS. 7A and 7B, it is also possible that the driving voltage is applied in the form of alternately increasing and decreasing pulses until the icon210reaches a first location240near the target location220, and after the first location240, the driving voltage continues to increase gradually. When the driving voltage continues to increase, the user may feel a continuous increase in rigidity of the screen after the first location240and thus recognize with his or her tactile sensation that the current input location is approaching the target location220. Upon a drop operation after the current input location reaches the target location220, a highest driving voltage may be applied to inform the user of completion of all inputs (drag & drop).

FIG. 8Aillustrates another exemplary continuous input to drag & drop a certain object while crossing a window border, andFIG. 8Bshows an exemplary driving voltage pattern that is applied when the continuous input illustrated inFIG. 8Ais conducted. Referring toFIG. 8A, a user inputs an instruction for dragging and dropping an icon (for example, a certain file) displayed on a screen from its initial location310to a target location320which is in a window screen, while crossing a window border350. Then, referring toFIG. 8B, while the user drags the icon310along a line330before crossing the window border350, no driving voltage or a low level of a driving voltage is applied to the peripheral regions of a current input location (the latest input location). Then, while the icon crosses the window border350and after the icon has crossed the window border350into the target location320, a relatively high level of driving voltage340is applied to the peripheral regions of the current input location. In this case, the user may feel little repulsive force or very small repulsive force against the screen when beginning to conduct a continuous input, and thereafter feel very great repulsive force against the screen after the item310has crossed the window border350. Accordingly, due to the difference in repulsive force, the user may recognize whether or not the current input location crosses the window border350with his or her tactile sensation. The stepped variation in driving voltage shown inFIG. 8Bis only exemplary, and a different driving voltage pattern (for example, a pulse wave, a sine wave, etc.) may be applied for the continuous input. Moreover, an inverse voltage pattern to that shown inFIG. 8Bmay be applied such that a user experiences the icon310“falling into” the target area320.

FIG. 9Ashows another example of a continuous input, andFIGS. 9B and 9Cshow exemplary driving voltage patterns that are applied when the continuous input illustrated inFIG. 9Ais conducted. Referring toFIG. 9B, a driving voltage which is applied to peripheral regions of a current input location (the latest input location) while a user moves a scroll bar up and down is in a pulse wave form, wherein the amplitude of the driving voltage may be pre-set based on the locations of the scroll bar. When a driving voltage is applied in a pulse wave form, the viscosity of electro-rheological fluid below the peripheral regions of a current input location alternately increases and decreases along with the movement of the current input location. As a result, repulsive force against the user's finger that slides along the scroll bar increases and decreases accordingly, so that the user may have a tactile sensation similar to that felt when rolling a scroll wheel of a mouse. In this case, since the user can recognize a traveling distance of the continuous input according to the number of sensed pulses, it is possible to adjust scrolling of the scroll bar precisely only by the tactile sensation.

Referring toFIG. 9C, while the user moves the scroll bar up or down, a driving voltage that is applied to the peripheral regions of the current input location (the latest input location) continues to increase, wherein the amplitude of the driving voltage may be pre-set based on a start position of the scroll bar. For example, as illustrated inFIG. 9C, the further the current input location moves from the start position of the scroll bar, the higher driving voltage is applied. In this case, when moving the scroll bar to a location close to the start position, the user may feel a small repulsive force against the screen and experience a low-speed scrolling, and when moving the scroll bar far away from the start position, a large repulsive force may be felt against the screen creating an experience of a fast-speed scrolling. Accordingly, it is possible to adjust a scroll speed only by use of tactile sensation.

By applying or modifying the embodiments described above, various effects may be obtained using the touch panel100. While only a few examples of various patterns have been discussed above, one of ordinary skill in the art will understand that by using various presentations on the screen and manipulating the driving voltages accordingly, virtually any pattern may be realized. As described above, the touch panel100provides a user with various tactile sensations upon conducting a continuous input so that the user can intuitively recognize a timing for terminating the continuous input and also is prevented from conducting any wrong inputs. Furthermore, when scrolling in a region of the touch panel100, a user may have a tactile sensation similar to that felt when rolling a scroll wheel of a mouse to be able to recognize an exact scrolled location and adjust scrolling accurately. In addition, in the case where a user conducts a specific continuous input (for example, sliding a finger on a user contact surface) to turn pages displayed on an e-book terminal, etc., the touch panel100may adjust repulsive force to provide the user with resistance similar to that felt when turning real pages.

By utilizing touch panels according to the above-described embodiments, it is possible to offer a sense of input or a tactile sensation to a user who conducts a continuous input. In addition, a user who conducts a continuous input on the touch panel may be prevented from conducting wrong inputs because the user can recognize a location at which the continuous input has to be terminated, or the existence of any objects or any window border on a traveling path of the continuous input through tactile sensation.