Display input device, and image forming apparatus including display portion

A display input device according to one aspect of the present disclosure includes display portion, piezoelectric element, drive portion, and detection portion. The display portion includes touch panel that detects touched position on display surface. The piezoelectric element is provided on touch panel and vibrates touch panel. In response to touch panel being touched, drive portion applies a voltage to piezoelectric element to vibrate piezoelectric element. The detection portion detects the voltage value of a voltage generated in piezoelectric element by a pressure being applied to piezoelectric element when touch panel is touched. The smaller the voltage value detected by detection portion is, the larger the voltage applied to piezoelectric element by drive portion for vibrating piezoelectric element is. The larger the voltage value detected by detection portion is, the smaller the voltage applied to piezoelectric element by drive portion for vibrating piezoelectric element is.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2012-190898 filed on Aug. 31, 2012, the entire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to a display input device, and an image forming apparatus including a display portion.

An image forming apparatus has a plurality of setting items for which the setting values can be changed upon execution of a job. Therefore, a general image forming apparatus includes a display input device for accepting an instruction to change each setting value.

The display input device of the image forming apparatus may include, as well as a hardware key, a display portion with a touch panel on which a software key, a menu, and the like are displayed. Such a display input device displays, on the display portion, a software key, a menu, and the like for accepting various settings, and detects a touched position (software key) touched via the touch panel, based on output of the touch panel.

However, in the case where various settings are accepted through a touching operation on the touch panel, a user cannot obtain a feeling (click feeling) as obtained when pressing the hardware key. Therefore, the user cannot instantaneously determine whether or not a touching operation performed on the touch panel has been definitely accepted, and thus the usability is poor.

A display input device that provides a click feeling to a user when the user touches a touch panel, is known. The display input device vibrates the touch panel in response to the touch panel being touched by a user. Specifically, a piezoelectric element is provided on the touch panel, so that the piezoelectric element is vibrated when a user touches the touch panel. As a result, the touch panel is vibrated.

Normally, in the known display input device, in order to prevent the piezoelectric element from being visible through the display screen, the piezoelectric element is provided at only a certain part (a part outside the valid display area) of the touch panel. Therefore, when a user touches the touch panel, the touched position may be a position near the providing position of the piezoelectric element or may be a position far from the providing position of piezoelectric element.

In this case, if the touched position is a position near the providing position of the piezoelectric element, vibration of the piezoelectric element is well transmitted to a finger of the user. However, if the touched position is a position far from the providing position of the piezoelectric element, vibration of the piezoelectric element is less transmitted to a finger of the user. That is, a click feeling (feeling of vibration caused by the piezoelectric element) provided when a user touches the touch panel is strengthened as the touched position comes close to the providing position of the piezoelectric element, and weakened as the touched position becomes away from the providing position of the piezoelectric element. Therefore, when a user touches the touch panel, the click feeling provided to a user varies depending on the touched position.

SUMMARY

A display input device according to one aspect of the present disclosure includes a display portion, a piezoelectric element, a drive portion, and a detection portion. The display portion includes a touch panel that detects a touched position on a display surface. The piezoelectric element is provided on the touch panel and vibrates the touch panel. In response to the touch panel being touched, the drive portion applies a voltage to the piezoelectric element to vibrate the piezoelectric element. The detection portion detects the voltage value of a voltage generated in the piezoelectric element by a pressure being applied to the piezoelectric element when the touch panel is touched. The smaller the voltage value detected by the detection portion is, the larger the voltage applied to the piezoelectric element by the drive portion for vibrating the piezoelectric element is. The larger the voltage value detected by the detection portion is, the smaller the voltage applied to the piezoelectric element by the drive portion for vibrating the piezoelectric element is.

An image forming apparatus according to another aspect of the present disclosure includes a display portion, a piezoelectric element, a drive portion, and a detection portion. The display portion includes a touch panel that detects a touched position on a display surface. The piezoelectric element is provided on the touch panel and vibrates the touch panel. In response to the touch panel being touched, the drive portion applies a voltage to the piezoelectric element to vibrate the piezoelectric element. The detection portion detects the voltage value of a voltage generated in the piezoelectric element by a pressure being applied to the piezoelectric element when the touch panel is touched. The smaller the voltage value detected by the detection portion is, the larger the voltage applied to the piezoelectric element by the drive portion for vibrating the piezoelectric element is. The larger the voltage value detected by the detection portion is, the smaller the voltage applied to the piezoelectric element by the drive portion for vibrating the piezoelectric element is.

DETAILED DESCRIPTION

Hereinafter, as an example of an image forming apparatus including a display input device according to one embodiment of the present disclosure, an image forming apparatus (multifunction peripheral) capable of executing a plurality of jobs such as copy, scanning, and facsimile will be described.

(Entire Configuration of Image Forming Apparatus)

As shown inFIG. 1, an image forming apparatus100of the present embodiment includes an operation panel101(corresponding to “display input device” described in claims), an image reading portion102, a sheet feed portion103, a paper sheet conveying portion104, an image forming portion105, and a fixing portion106.

As shown inFIG. 2, the operation panel101includes a liquid crystal display portion11(corresponding to “display portion” described in claims). The liquid crystal display portion11includes a liquid crystal display panel12and a touch panel13, and a display surface12aof the liquid crystal display panel12is covered by the touch panel13. The liquid crystal display panel12displays a software key or a menu for accepting various settings, on the display surface12a. The touch panel13is provided for detecting a touched position on the display surface12aof the liquid crystal display panel12.

In addition, the liquid crystal display portion11(the liquid crystal display panel12and the touch panel13) is held by a housing case14forming an outer framework of the operation panel101. The housing case14has an opening14aformed thereon. In the state in which the liquid crystal display portion11is held by the housing case14, a valid display area of the liquid crystal display panel12is exposed from the opening14aof the housing case14.

It is noted that the operation panel101also has, as hardware keys, a numeric keypad15for accepting a numeric input, a start key16for accepting an instruction to execute a job, and the like.

As shown inFIG. 1, the image reading portion102reads a document sheet and generates image data of an image to be formed. In the image reading portion102, optically-relevant members such as an exposure lamp, a mirror, a lens, and an image sensor are provided though not shown. The image reading portion102radiates light onto a document sheet placed on the contact glass21. Then, the image reading portion102performs A/D conversion for an output value of the image sensor receiving light reflected from the document sheet, thereby generating image data. Thus, the image forming apparatus100can perform printing based on the image data obtained by the reading operation (scanning) of the document sheet performed by the image reading portion102. In addition, the image forming apparatus100can also store the image data obtained by the scanning. It is noted that in the image reading portion102, a document sheet holding portion22that holds a document sheet placed on the contact glass21is provided.

The sheet feed portion103includes a cassette31that contains a paper sheet P, and feeds a paper sheet P in the cassette31to a paper sheet conveyance path. In addition, the sheet feed portion103includes a pick-up roller32, a separating roller pair33, and the like for feeding one by one a paper sheet P in the cassette31to the paper sheet conveyance path. The pick-up roller32takes out a paper sheet P from the cassette31. The separating roller pair33prevents multi feed of the paper sheet P.

The paper sheet conveying portion104conveys a paper sheet P fed to the paper sheet conveyance path, along the paper sheet conveyance path (toward a discharge tray41). The paper sheet conveying portion104includes a plurality of conveying roller pairs42rotatably provided on the paper sheet conveyance path. In addition, the paper sheet conveying portion104includes a registration roller pair43provided at a position on the upstream side in the paper sheet conveyance direction of the image forming portion105(at a position just before reaching the image forming portion105). The registration roller pair43causes a paper sheet P to stand by just before the image forming portion105, and conveys the paper sheet P to the image forming portion105at an appropriate timing.

The image forming portion105forms a toner image based on image data of an image to be formed, and transfers the toner image onto the paper sheet P. The image forming portion105includes a photosensitive drum51, a charging device52, an exposure device53, a developing device54, a transfer roller55, and a cleaning device56.

Upon image formation, first, the photosensitive drum51is rotationally driven and the charging device52charges the surface of the photosensitive drum51at a predetermined potential. In addition, the exposure device53outputs a light beam L based on image data of an image to be formed, thereby scanning and exposing the surface of the photosensitive drum51with the light beam L. Thus, an electrostatic latent image is formed on the surface of the photosensitive drum51. The developing device54supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum51, thereby developing the image.

The transfer roller55can be rotated while pressing the surface of the photosensitive drum51. The registration roller pair43causes a paper sheet P to proceed between the transfer roller55and the photosensitive drum51at an appropriate timing. At this time, a transfer voltage is applied to the transfer roller55. Thus, a toner image on the surface of the photosensitive drum51is transferred onto the paper sheet P. Thereafter, the cleaning apparatus56eliminates residual toner and the like on the surface of the photosensitive drum51.

The fixing portion106heats and pressurizes a toner image transferred onto a paper sheet P, thereby fixing the toner image. The fixing portion106includes a heating roller61and a pressure roller62. The heating roller61includes a heater63. The pressure roller62is pressed to the heating roller61. The paper sheet P having the toner image transferred thereon passes between the heating roller61and the pressure roller62, whereby the paper sheet P is heated and pressed. Thus, the toner image is fixed on the paper sheet P, whereby the printing is completed. Thereafter, the printed paper sheet P is conveyed to the discharge tray41by the conveying roller pair42.

(Hardware Configuration of Image Forming Apparatus)

As shown inFIG. 3, the image forming apparatus100includes a main control portion110that controls the entire apparatus. The main control portion110includes a CPU111, an image processing portion112, and a storage portion113. The image processing portion112includes a dedicated ASIC for image processing, a memory, and the like, and performs various image processes (such as expansion/reduction, density conversion, and data form conversion) for image data. The storage portion113includes a ROM, a RAM, an HDD, and the like. For example, a program and data needed for executing a job are stored in the ROM, and the program and the data are expanded on the RAM.

The image reading portion102, the sheet feed portion103, the paper sheet conveying portion104, the image forming portion105, and the fixing portion106are connected to the main control portion110, and each operate based on an instruction from the main control portion110. Further, the main control portion110is connected to a communication portion120, and controls communication performed with external equipment200(for example, a personal computer, a server, a facsimile, and the like).

As shown inFIG. 4, the operation panel101includes a panel control portion130connected to the main control portion110. The panel control portion130includes a CPU133and a storage portion134. In response to an instruction from the main control portion110, the panel control portion130controls a display operation of the operation panel101. For example, the panel control portion130causes the liquid crystal display panel12to display a software key and a menu for accepting various settings, and when a touching operation of touching the touch panel13is performed, detects the coordinates of the touched position based on the output of the touch panel13. It is noted that data indicating the correspondence between the output of the touch panel13and the coordinates of the touched position is stored in the storage portion134.

(Provision of Click Feeling Upon Touching Operation)

When the operation panel101has accepted a touching operation from a user, the operation panel101vibrates the touch panel13in order to provide a feeling (click feeling) as obtained when pressing the hardware key, to a user. Specifically, the piezoelectric element17that vibrates the touch panel13is provided on the touch panel13. For example, the piezoelectric element17is provided between the liquid crystal display panel12and the touch panel13. A drive portion131that drives the piezoelectric element17applies a voltage to the piezoelectric element17to vibrate the piezoelectric element17when the panel control portion130has detected a touch on the touch panel13. Thus, when a user touches the touch panel13, the touch panel13provided with the piezoelectric element17is also vibrated, whereby the user can obtain a click feeling.

The piezoelectric element17is formed by interposing a piezoelectric body made of a piezoelectric ceramic such as PZT (lead zirconate titanate) between a pair of electrodes. The piezoelectric element17thus formed is displaced (warps) in accordance with an application voltage. For example, after the piezoelectric element17warps by a predetermined voltage being applied thereto, the warp reduces as the application voltage is reduced, and the piezoelectric element17returns to its original shape when the application of voltage is stopped. Therefore, for vibrating the piezoelectric element17, the drive portion131periodically changes the application voltage to the piezoelectric element17(changes the waveform of the application voltage to the piezoelectric element17to a rectangular wave, a sine wave, a saw-tooth wave, a triangular wave, or the like). Thus, the piezoelectric element17is vibrated and the touch panel13provided with the piezoelectric element17is also vibrated.

In addition, as shown inFIG. 5, a plurality of the piezoelectric elements17are provided on the touch panel13(between the liquid crystal display panel12and the touch panel13). As an example,FIG. 5shows the case where six piezoelectric elements17are provided on the touch panel13. It is noted that the providing number of the piezoelectric elements17is not specifically limited. The providing number may be one to five or may be seven or more.

As an example of the plurality of piezoelectric elements17, in a plane view, three piezoelectric elements17are provided on each of a pair of sides (inFIG. 5, the upper side and the lower side) parallel with each other on the touch panel13. In addition, the plurality of piezoelectric elements17are positioned in an area outside a valid display area (area surrounded by a dashed line) so that the piezoelectric elements17are invisible through the screen.

(Correction of Application Voltage to Piezoelectric Element)

A click feeling (feeling of vibration caused by the piezoelectric element17) provided when a user touches the touch panel13is strengthened as the touched position comes close to the providing position of the piezoelectric element17, and weakened as the touched position becomes away from the providing position of the piezoelectric element17. In addition, when a user strongly touches the touch panel13, vibration is well transmitted to a finger and therefore a click feeling is strengthened, and when a user weakly touches the touch panel13, vibration is less transmitted to a finger and therefore a click feeling is weakened.

It is noted that in the structure in which the plurality of piezoelectric elements17are provided on the touch panel13, there may be variations in the attachment accuracies of the plurality of piezoelectric elements17on the touch panel13. In this case, a click feeling provided to a user varies between when the user touches the vicinity of the providing position of the piezoelectric element17with a low attachment accuracy (for example, the piezoelectric element17with a gap formed between the piezoelectric element17and the touch panel13) and when the user touches the vicinity of the providing position of the piezoelectric element17with a high attachment accuracy, even if both touched positions are in the vicinity of the providing position of the piezoelectric element17. That is, when a user touches the vicinity of the providing position of the piezoelectric element17with a low attachment accuracy, a click feeling provided to the user is weaker than when a user touches the vicinity of the providing position of the piezoelectric element17with a high attachment accuracy (vibration caused by the piezoelectric element17is less transmitted to a finger because of a gap formed between the piezoelectric element17and the touch panel13).

Here, when the touch panel13is touched by a user, a pressure is applied to the piezoelectric element17, whereby the piezoelectric element17is displaced. At this time, electric charge is generated in the piezoelectric element17. That is, a voltage is generated in the piezoelectric element17. As shown inFIG. 6, the voltage generated in the piezoelectric element17increases as the displacement of the piezoelectric element17increases. Therefore, when the touch panel13is touched by a user, the closer to the providing position of the piezoelectric element17the touched position is or the larger the pressing force upon the touching is, the larger the pressure applied to the piezoelectric element17(the displacement of the piezoelectric element17) is and the larger the voltage generated in the piezoelectric element17is. In addition, the higher the attachment accuracy of the piezoelectric element17is, the larger the pressure applied to the piezoelectric element17(the displacement of the piezoelectric element17) is and the larger the voltage generated in the piezoelectric element17is.

Accordingly, in the present embodiment, in order to reduce variation in a click feeling provided when a user touches the touch panel13, the application voltage to the piezoelectric element17for vibrating the piezoelectric element17is changed in accordance with a voltage generated in the piezoelectric element17when a user touches the touch panel13(a drive voltage for driving the piezoelectric element17is not fixed).

For example, as shown inFIG. 4, a voltage detection portion132that detects the voltage value of a voltage generated in the piezoelectric element17is connected to the piezoelectric element17. When a user touches the touch panel13, the voltage detection portion132converts electric charge generated in the piezoelectric element17into a voltage, amplifies the voltage, and outputs the amplified voltage to panel control portion130. By receiving the output signal from the voltage detection portion132, the panel control portion130detects the voltage value (the maximum value of amplitude) of the voltage generated in the piezoelectric element17when the user has touched touch panel13. It is noted that in this configuration, the panel control portion130connected to the voltage detection portion132corresponds to a “detection portion” described in claims.

The smaller the voltage value detected when the user has touched the touch panel13is, the larger the panel control portion130makes the application voltage to the piezoelectric element17for vibrating the piezoelectric element17. That is, the drive portion131increases the amplitude (maximum voltage value) of a voltage to be applied to the piezoelectric element17for vibrating the piezoelectric element17. On the other hand, the larger the voltage value detected when the user has touched the touch panel13is, the smaller the panel control portion130makes the application voltage to the piezoelectric element17for vibrating the piezoelectric element17. That is, the drive portion131decreases the amplitude (maximum voltage value) of a voltage to be applied to the piezoelectric element17for vibrating the piezoelectric element17.

Thus, when a user touches the touch panel13, if vibration caused by the piezoelectric element17is well transmitted to a finger of the user, the vibration of the piezoelectric element17becomes small, and if vibration caused by the piezoelectric element17is less transmitted to a finger of the user, the vibration of the piezoelectric element17becomes large. As a result, variation in a click feeling (feeling of vibration caused by the piezoelectric element17) provided to a user can be suppressed.

For example, if the voltage value detected by the panel control portion130is within a voltage range RS shown inFIG. 6, the drive portion131keeps the amplitude (maximum voltage value) of a voltage to be applied to the piezoelectric element17at a predetermined reference value. If the voltage value detected by the panel control portion130is below the voltage range RS, the drive portion131increases the amplitude (maximum voltage value) of a voltage to be applied to the piezoelectric element17, to be larger than the reference value. On the other hand, if the voltage value detected by the panel control portion130is above the voltage range RS, the drive portion131decreases the amplitude (maximum voltage value) of a voltage to be applied to the piezoelectric element17, to be smaller than the reference value.

As a result, for example, when a user touches the touch panel13, the closer to the touched position the piezoelectric element17is, the smaller the voltage supplied to the piezoelectric element17is (the smaller the vibration of the piezoelectric element17is). On the other hand, the farther from the touched position the piezoelectric element17is, the larger the voltage supplied to the piezoelectric element17is (the larger the vibration of the piezoelectric element17is). If the voltage value detected by the panel control portion130is within the predetermined voltage range RS, the voltage to be applied to the piezoelectric element17is kept at the reference value.

It is noted that, for example, even if the piezoelectric element17is close to the touched position, if the pressing force upon the touching is small, the piezoelectric element17is not displaced so much. Therefore, the voltage value detected by the panel control portion130(voltage generated in the piezoelectric element17) can be below the voltage range RS. In addition, if the touched position is near the piezoelectric element17with a low attachment accuracy, similarly, the voltage value detected by the panel control portion130(voltage generated in the piezoelectric element17) can be below the voltage range RS. In such a case, even though the piezoelectric element17is close to the touched position, the voltage supplied to the piezoelectric element17becomes large (the vibration of the piezoelectric element17becomes large). That is, in the present embodiment, the application voltage to the piezoelectric element17for vibrating the piezoelectric element17varies depending on the touched position, the pressing force upon the touching, the attachment accuracy of the piezoelectric element17, and the like.

As shown inFIG. 5, a plurality of piezoelectric elements17may be provided on the touch panel13. In this case, when the touch panel13is touched, the panel control portion130receives an output signal from the voltage detection portion132and thereby detects all the voltage values of voltages generated in the plurality of piezoelectric elements17. Then, the drive portion131adjusts the application voltages to the plurality of piezoelectric elements17individually in accordance with the voltage values of voltages generated in the plurality of piezoelectric elements17. At this time, the drive portion131increases the application voltage to the piezoelectric element17whose voltage value detected by the panel control portion130is below the voltage range RS, among the plurality of piezoelectric elements17, to be larger than the reference value. Meanwhile, the drive portion131decreases the application voltage to the piezoelectric element17whose voltage value detected by the panel control portion130is above the voltage range RS, to be smaller than the reference value.

Thus, it is possible to increase the vibration of the piezoelectric element17whose voltage value detected by the panel control portion130is below the predetermined voltage range RS, among the plurality of piezoelectric elements17, and decrease the vibration of the piezoelectric element17whose voltage value detected by the panel control portion130is above the predetermined voltage range RS.

In addition, a touched position or a pressing force upon touching differs depending on each touching operation on the touch panel13. Therefore, the drive portion131adjusts the application voltage to the piezoelectric element17based on the voltage value detected by the panel control portion130, every time the touch panel13is touched. Thus, even if a user successively touches the touch panel13several times, variation in a click feeling provided to the user at this time can be suppressed.

Next, with reference to a flowchart shown inFIG. 7, a flow to provide a click feeling to a user performing a touching operation will be described.

First, at the start of the flowchart inFIG. 7, it is assumed that the main power supply for the image forming apparatus100has been turned on, and a menu screen, a setting screen, or the like that requires an input through a touching operation is displayed on the operation panel101(liquid crystal display panel12). Then, when a user touches the touch panel13, the flowchart inFIG. 7is started. It is noted that when a user touches the touch panel13, a pressure is applied to the piezoelectric element17, whereby the piezoelectric element17is displaced and a voltage is generated in the piezoelectric element17.

In step S1, the panel control portion130acquires an output signal (a signal indicating the voltage value of the voltage generated in the piezoelectric element17) from the voltage detection portion132. In step S2, based on the output of the voltage detection portion132, the panel control portion130detects the voltage value (the maximum value of amplitude) of the voltage generated in the piezoelectric element17. At this time, if a plurality of piezoelectric elements17are provided on the touch panel13, the panel control portion130detects all the voltage values of the voltages generated in the plurality of piezoelectric elements17.

In step S3, the panel control portion130determines whether or not the detected voltage value is within a predetermined voltage range RS. As a result of the determination, if the detected voltage value is within the predetermined voltage range RS, the process proceeds to step S4. In step S4, the panel control portion130sets a voltage value (application voltage to the piezoelectric element17) for vibrating the piezoelectric element17, at a predetermined reference value. On the other hand, if the detected voltage value is not within the predetermined voltage range RS, the process proceeds to step S5.

In step S5, the panel control portion130determines whether or not the detected voltage value is below the predetermined voltage range RS. As a result of the determination, if the detected voltage value is below the predetermined voltage range RS, the process proceeds to step S6. On the other hand, if the detected voltage value is not below the predetermined voltage range RS, that is, if the detected voltage value is above the predetermined voltage range RS, the process proceeds to step S7.

Then, in step S6subsequent to step S5, the panel control portion130sets the voltage value for vibrating the piezoelectric element17to a (predetermined) value larger than the reference value. On the other hand, in step S7subsequent to step S5, the panel control portion130sets the voltage value for vibrating the piezoelectric element17to a (predetermined) value smaller than the reference value.

After step S4, step S6, or step S7, the process proceeds to step S8. In step S8, the panel control portion130instructs the drive portion131to apply the set voltage to the piezoelectric element17, to vibrate the piezoelectric element17(touch panel13). For example, the panel control portion130vibrates the piezoelectric element17until a predetermined time elapses. Alternatively, the operation panel130vibrates the piezoelectric element17until the touch on the touch panel13is released.

In step S9, the operation panel101determines whether or not the touch panel13has been newly touched, based on output from the touch panel13. As a result of the determination, if the touch panel13has been newly touched, the process proceeds to step S1. If the touch panel13has not been newly touched, the process is ended.

In the operation panel101(display input device) of the present embodiment, when a user touches the touch panel13, if vibration caused by the piezoelectric element17is well transmitted to a finger of the user, the vibration of the piezoelectric element17becomes small, and if vibration caused by the piezoelectric element17is less transmitted to a finger of the user, the vibration of the piezoelectric element17becomes large. As a result, variation in a click feeling (feeling of vibration caused by the piezoelectric element) provided to the user can be suppressed.