JP2017194912A - Image forming apparatus, display device, and method for detecting touch position on display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which: a reduction in touch detection sensitivity accompanying a deterioration with time of a touch panel extends the time required for detecting a touch position and impairs touch responsiveness.SOLUTION: A detection signal acquisition part 51b included in a display device 41 with a touch panel causes a first state storage part 32a to store first state detection data in a first state where a touch panel 52 is not touched, and causes a second state storage part 32b to store second state detection data in a second state where the touch panel 52 is touched. A touch position detection part 51c detects, as a touch position, a position on the touch panel 52 where the difference value determined from the first state detection data and second state detection data is equal to or larger than a predetermined threshold.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus, a display apparatus, and a touch position detection method for the display apparatus.

  2. Description of the Related Art Conventionally, there are display devices that include a touch panel that enables a touch operation using a user's finger or a touch pen on a display screen. This display device is used in mobile electronic devices such as PDAs (Personal Digital Assistants) and portable terminals, image forming devices, various home appliances, and the like. As a method for realizing a touch panel, for example, a resistance film method that detects a change in resistance value of a touched portion, a capacitance method that detects a change in parasitic capacitance generated between the touched portion and a finger, or a change in light amount There are known optical sensor systems for detecting.

For example, techniques disclosed in Patent Documents 1 and 2 are known as capacitive touch panels.
The input processing unit disclosed in Patent Document 1 includes scanning electrodes (Y electrodes) for applying scanning signals arranged in a vertical and horizontal two-dimensional matrix, and detection electrodes (X for detecting detection signals orthogonal to the scanning electrodes) The capacitance of each electrode is detected based on the electrode). The input processing unit can detect the parasitic capacitance of each electrode that increases when a finger or other conductor touches the surface of the touch panel, and can calculate input coordinates based on the capacitance change signal detected by each electrode. Become.

  Patent Document 2 proposes a method for correcting detection sensitivity that decreases as the detection electrode deteriorates with time.

JP 2010-256956 A JP 2013-222387 A

  In order to correct the detection sensitivity by the method disclosed in Patent Document 2, the scan electrode and the detection electrode formed on the touch panel disclosed in Patent Document 1 need to acquire a high voltage detection signal. is there. In this case, a functional unit (for example, a DC-DC converter) for increasing the voltage of the scanning signal has to be added to the touch panel drive circuit, resulting in an increase in circuit cost. In order to correct the detection sensitivity, it is necessary to lengthen the acquisition time of the detection signal, increase the number of inputs for detecting the detection signal, or increase the number of detection integrations. As a result, the detection time of the touch position is delayed, and the touch response of the touch panel is deteriorated.

  The present invention has been made in view of such a situation, and an object of the present invention is to cope with a decrease in detection sensitivity accompanying a temporal deterioration of scan electrodes and detection electrodes formed on a touch panel.

An image forming apparatus according to the present invention includes an image forming apparatus main body and a display device.
The image forming apparatus main body includes an image forming unit that performs image forming processing based on an instruction through the display device.
The display device includes a display panel for displaying an image, a touch panel superimposed on the display panel, a plurality of scan electrodes formed on the touch panel, a plurality of detection electrodes formed on the touch panel and intersecting the plurality of scan electrodes, A scanning signal supply unit, a detection signal acquisition unit, and a touch position detection unit are included, and the touch position is detected by a touch position detection method of the display device.
Here, the scanning signal supply unit supplies a scanning signal to the plurality of scanning electrodes.
The detection signal acquisition unit stores first state detection data based on detection signals acquired from the plurality of detection electrodes in a first state where the touch on the touch panel is not performed in the first state storage unit, and the touch on the touch panel is performed. Second state detection data based on detection signals acquired from the plurality of detection electrodes in the second state is stored in the second state storage unit.
The touch position detection unit detects the position of the touch panel where the difference value obtained from the first state detection data read from the first state storage unit and the second state detection data read from the second state storage unit is equal to or greater than a predetermined threshold. Detect as touch position.

According to the present invention, even if the detection sensitivity decreases with the aging deterioration of the scanning electrode and the detection electrode, the detection sensitivity can be favorably maintained without delaying the time for detecting the touch position.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is a schematic diagram illustrating a hardware configuration example of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating a schematic configuration example of an image forming apparatus main body according to an embodiment of the present invention. 1 is a block diagram illustrating a schematic configuration of a display device with a touch panel according to an embodiment of the present invention. It is a block diagram which shows the internal structure example of the touchscreen control part and RAM which concern on the example of 1 embodiment of this invention. It is an enlarged view which shows the electrode pattern of the touchscreen which concerns on one embodiment of this invention. It is a fragmentary sectional view of the touch panel in the AA line of FIG. It is explanatory drawing which shows the mode of the touch sensing based on one embodiment of this invention. It is explanatory drawing which shows a mode that the touchscreen which concerns on one embodiment of this invention changes with time. FIG. 6 is a state transition diagram of the image forming apparatus main body according to the embodiment of the present invention. 6 is a table showing a relationship between an MFP state transition transition trigger and a transition state of the image forming apparatus main body according to the embodiment of the present invention. It is a flowchart which shows the example of the collection method of the 1st state detection data in the 1st state where the touch operation which concerns on one embodiment of this invention is not performed. It is a flowchart which shows the example of the collection method of the 2nd state detection data in the 2nd state in which the touch operation which concerns on the example of 1 embodiment of this invention is performed. It is explanatory drawing which shows the example of the 1st state detection data and the 2nd state detection data in the sensor part of the touchscreen which concerns on the example of 1 embodiment of this invention.

[One Embodiment]
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same function or configuration are denoted by the same reference numerals, and redundant description is omitted.

<Example of Hardware Configuration of Image Forming Apparatus>
FIG. 1 is a schematic diagram illustrating a hardware configuration example of the image forming apparatus 1.
The image forming apparatus 1 includes an image forming apparatus main body 2 and a post-processing apparatus FN.

  The image forming apparatus main body 2 employs an electrophotographic method for forming an image using static electricity. For example, four color toners of Y (yellow), M (magenta), C (cyan), and K (black) are used. Color printing with superimposed images is possible. The image forming apparatus main body 2 includes an automatic document feeder (ADF) 4, an operation unit 5, a paper feeding unit 6, an image forming unit 20, an intermediate transfer belt 21 (image carrier), and secondary transfer. Section 22, fixing section 23, and paper discharge tray 24.

  The automatic document feeder 4 automatically feeds a document when the document is read. A scanner 46 (see FIG. 2 described later) provided in the automatic document feeder 4 is automatically conveyed by a document placed on the upper platen glass of the image forming apparatus main body 2 or by the automatic document feeder 4. The original image can be read.

  The operation unit 5 includes, for example, a display device 41 with a touch panel for instructing the start of various jobs such as image forming processing, and a power key 42 (see FIG. 2 to be described later) capable of switching the sub power supply ON or OFF. The display device 41 with a touch panel can be operated by the user and display various information. Note that the operation unit 5 may be configured with a mouse, an operation switch, or the like that is separate from the display device 41 with a touch panel.

  The paper feed unit 6 includes a plurality of paper storage units according to the size and type of paper. In the paper feeding unit 6, when a corresponding paper storage unit is selected based on an instruction from the image forming apparatus main body 2, the paper is taken out from the paper storage unit and sent to the conveyance path C.

  The image forming unit 20 includes four image forming units 7Y, 7M, 7C, and 7K in order to form toner images of each color of Y, M, C, and K. The image forming unit 20 controls the operations of the image forming units 7Y, 7M, 7C, and 7K of the image forming unit 20 to form Y, M, C, and K toner images. The image forming apparatus main body 2 can cause the image forming unit 20 to perform image forming processing based on an instruction through the display device 41 with a touch panel of the operation unit 5. In addition, the image forming apparatus main body 2 includes a plurality of rollers (conveyance rollers) for conveying the sheet to the conveyance path C. These rollers are usually constituted by a pair of rollers.

  In the image forming mode, the image forming apparatus main body 2 charges the photosensitive member included in the image forming units 7Y, 7M, 7C, and 7K, erases the charge, exposes it, and forms an electrostatic latent image on the photosensitive member. Then, toner is attached to the electrostatic latent images on the Y, M, C, and K photoconductors using a developing unit to form toner images of the respective colors. Next, the toner images formed on the Y, M, C, and K photoconductors are sequentially primary-transferred onto the surface of the intermediate transfer belt 21 that rotates in the direction of the arrow.

  Next, the toner images of the respective colors primarily transferred onto the intermediate transfer belt 21 by the secondary transfer unit 22 (secondary transfer roller) are secondarily applied to a sheet supplied from the sheet feeding unit 6 and conveyed by the roller. Transcript. Each color toner image on the intermediate transfer belt 21 is secondarily transferred to a sheet to form a color image. The image forming apparatus main body 2 conveys the sheet on which the color toner image is formed to the fixing unit 23.

  The fixing unit 23 is a device that performs a fixing process on a sheet on which a color toner image is formed. The fixing unit 23 pressurizes and heats the conveyed paper, and fixes the transferred toner image on the paper. The fixing unit 23 includes, for example, an upper fixing roller and a lower fixing roller (not shown) that are fixing members. The upper fixing roller and the lower fixing roller are arranged in pressure contact with each other, and a fixing nip portion is formed as a pressing portion between the upper fixing roller and the lower fixing roller.

A heating unit (not shown) is provided inside the fixing upper roller. The roller part at the outer peripheral part of the fixing upper roller is heated by the radiant heat from the heating part. The sheet is conveyed to the fixing nip so that the surface on which the toner image is transferred by the secondary transfer unit 22 (fixing target surface) faces the fixing upper roller. The sheet passing through the fixing nip is subjected to pressure by the upper fixing roller and the lower fixing roller, and heating by the heat of the upper fixing roller. The sheet on which the fixing process has been performed by the fixing unit 23 is discharged to the post-processing device FN. Then, after the predetermined post-processing set for the print job is performed by the post-processing device FN, the paper is discharged to the paper discharge tray 24. The user acquires the paper discharged to the paper discharge tray 24 as a printed matter.
In the present embodiment, the image forming apparatus 1 that forms a color image is illustrated, but an image forming apparatus that forms a monochrome image may be used.

<Schematic configuration example of image forming apparatus main body>
FIG. 2 is a block diagram illustrating a schematic configuration of the image forming apparatus main body 2.

  The image forming apparatus main body 2 is a so-called multi function printer (MFP) having a copy function, a scan function, a print function, and the like. The copy function is a function for optically reading a document and printing a duplicate image on paper. The scan function is a function of saving image data of a read original as a file, or transmitting image data to a PC terminal or the like through the network N. The print function is a function for printing a document or an image on a sheet based on a print job received from the outside through the network N or a print job instructed to be printed by the operation unit 5 and outputting it.

  The image forming apparatus main body 2 includes a control unit 30 that comprehensively controls the operation of the image forming apparatus main body 2. The control unit 30 executes various processes by the CPU. Connected to the control unit 30 are ROM 31, RAM 32, nonvolatile memory 33, HDD 34, communication interface 35, operation unit 5, printing interface 44, reading interface 45, user ID reading unit 47, main power switch 48, and the like. The image forming unit 20 is connected to the print interface 44. A scanner 46 is connected to the reading interface 45.

The control unit 30 is based on an OS (Operating System) program and executes programs such as middleware and application programs.
Various programs are stored in the ROM 31, and each function of the image forming apparatus main body 2 is realized by the control unit 30 executing processing according to these programs.
The RAM 32 is used as a work memory for temporarily storing various data and image forming data when the control unit 30 or the display device 41 with a touch panel executes a program.
Various settings are stored in the nonvolatile memory 33.
The HDD 34 stores print jobs received by the communication interface 35 from a PC terminal, various setting files, and the like.
The communication interface 35 can receive a print job from a PC terminal or the like through the network N.

  The operation unit 5 includes various operation switches such as a start button in addition to the display device 41 with a touch panel and the power key 42. The user uses the operation unit 5 to give an instruction (print instruction or the like) to the image forming apparatus 1.

The display device 41 with a touch panel includes a liquid crystal display (LCD) or the like, and has a function of displaying various operation screens, setting screens, and the like. The touch panel-equipped display device 41 detects a coordinate position pressed by a touch pen, a finger, or the like, or detects a flick operation, a drag operation, an operation on a scroll bar, or the like.
The power key 42 changes the state of the image forming apparatus main body 2 (hereinafter referred to as “MFP state”) to a standby state, a power saving state, or a sub power supply OFF state, as shown in FIGS.

The image forming unit 20 is connected to the print interface 44, and image forming data created by the control unit 30 is transmitted to the image forming unit 20.
The image forming unit 20 performs image forming processing for forming an image on a sheet based on the image forming data under the control of the control unit 30.

Connected to the reading interface 45 is a scanner 46 that functions to optically read a document and acquire image data.
The scanner 46 includes, for example, a line image sensor, a moving unit, an optical path, a data conversion unit, and the like. The line image sensor reads a document for one line in the width direction by receiving a light source for irradiating light to the document and the reflected light. The moving unit sequentially moves the reading position in units of lines in the length direction of the document. The optical path is composed of a lens, a mirror, or the like that forms an image by guiding the reflected light from the document to the line image sensor. The data converter converts the analog image signal output from the line image sensor into digital image data.

  The user ID reading unit 47 reads a user ID from an IC (Integrated Circuit) card held by the user. The user ID read by the user ID reading unit 47 is subjected to user authentication by the control unit 30.

  The main power switch 48 is used to control the start or stop of the image forming apparatus main body 2. When the main power switch 48 is turned on, the image forming apparatus body 2 is activated, and when the main power switch 48 is turned off, the image forming apparatus body 2 is stopped.

<Schematic configuration example of a display device with a touch panel>
FIG. 3 is a block diagram illustrating a schematic configuration of the display device 41 with a touch panel.
The display device 41 with a touch panel includes a touch panel control unit 51, a capacitive touch panel 52, a display control circuit 53, and a display panel 54.

  The touch panel 52 is superposed on the display panel 54 (for example, a liquid crystal display) with an adhesive. As shown in FIG. 5 described later, the touch panel 52 includes a plurality of scan electrodes (Y electrodes) used for applying a scan signal, and a plurality of detection electrodes used for detecting a detection signal across the scan electrode. (X electrode). The touch panel 52 is installed on the front surface of the display panel 54. Therefore, when the user views the image displayed on the display panel 54, the display image needs to pass through the touch panel 52, and thus the touch panel 52 desirably has a high light transmittance.

The scan electrode and the detection electrode of the touch panel 52 are connected to the touch panel control unit 51 by a wiring 62.
The touch panel control unit 51 sequentially applies scanning signals to the scanning electrodes, measures the interelectrode capacitance at the intersection of the scanning electrode and the detection electrode, and performs a touch operation position based on the capacitance value of the intersection between the electrodes ( Calculate the input coordinates of (touch position). The touch panel control unit 51 transfers the input coordinates to the control unit 30 using the I / F signal 61.

  When the input coordinates are transferred from the touch panel 52 by the touch operation, the control unit 30 transfers the display image generated according to the touch operation to the display control circuit 53 as the display control signal 63.

The display control circuit 53 generates a display signal 64 according to the display image transferred by the display control signal 63 and displays the image on the display panel 54.
The display panel 54 is not limited to a liquid crystal display as long as the touch panel 52 can be used, and a display panel using an organic light emitting diode element or a surface conduction electron-emitting element, or an organic EL display panel can also be used. It can be used.

FIG. 4 is a block diagram illustrating an internal configuration example of the touch panel control unit 51 and the RAM 32.
The touch panel control unit 51 includes a scanning signal supply unit 51a, a detection signal acquisition unit 51b, and a touch position detection unit 51c.

The scanning signal supply unit 51 a supplies a scanning signal to a plurality of scanning electrodes provided on the touch panel 52.
The detection signal acquisition unit 51 b acquires a detection signal from the detection electrode of the touch panel 52. Here, the detection signal acquisition unit 51b causes the first state storage unit 32a to store first state detection data based on detection signals acquired from the plurality of detection electrodes in the first state where the touch panel 52 is not touched. . In addition, the detection signal acquisition unit 51b causes the second state storage unit 32b to store second state detection data based on detection signals acquired from the plurality of detection electrodes in the second state where the touch panel 52 is touched. For example, the first state detection data and the second state detection data are obtained by performing A / D (Analog / Digital) conversion on the voltage peak of the detection signal, which is an analog value, in the range of “0” to “255” in 8-bit gradation. Value.

  The touch position detection unit 51c is a touch panel in which a difference value obtained from the first state detection data read from the first state storage unit 32a and the second state detection data read from the second state storage unit 32b is equal to or greater than a predetermined threshold. The position 52 is detected as the touch position. The predetermined threshold value may be stored in the RAM 32 or may be held by the touch position detection unit 51c.

The RAM 32 includes a first state storage unit 32a and a second state storage unit 32b.
The first state storage unit 32a stores first state detection data based on the detection signal acquired by the detection signal acquisition unit 51b in the first state. The first state detection data is transferred from the standby state to the power saving state or the stopped state (sub power supply OFF state, ErP auto power OFF state described later), and the display panel 54 displays black (blackout). ) Is stored in the first state storage unit 32a by the detection signal acquisition unit 51b. In addition, the detection signal acquisition unit 51b periodically stores the first state detection data in the first state storage unit 32a. Therefore, the first state detection data stored in the first state storage unit 32a is updated with the latest first state detection data acquired by the detection signal acquisition unit 51b.

The second state storage unit 32b stores second state detection data based on the detection signal acquired by the detection signal acquisition unit 51b in the second state. The second state detection data is stored in the second state storage unit 32b by the detection signal acquisition unit 51b when the image forming apparatus main body 2 is in the standby state.
Note that the first state storage unit 32 a and the second state storage unit 32 b may be configured in the nonvolatile memory 33 or the HDD 34.

Next, the basic principle of the capacitive touch panel 52 will be described.
FIG. 5 is an enlarged view showing an electrode pattern of the touch panel 52.
The touch panel 52 includes four scanning electrodes Tx1 to Tx4 as Y electrodes and four detection electrodes Rx1 to Rx4 as X electrodes, but the number of electrodes is not limited thereto. Since the touch panel 52 is provided on the display panel 54, a transparent and high-transmittance material is essential. For this reason, the touch panel 52 is comprised by the transparent conductive films 71 and 72 which consist of ITO (Indium Tin Oxide), for example (in the figure, the transparent conductive films 71 and 72 are described as ITO). The scan electrodes Tx1 to Tx4 are formed by a transparent conductive film 71 in the Y direction on the sensor glass 70, and the detection electrodes Rx1 to Rx4 are formed by a transparent conductive film 72 connected by a metal bridge 73 in the X direction.

FIG. 6 is a partial cross-sectional view of the touch panel 52 taken along line AA in FIG.
The transparent conductive film 71 used as the scan electrodes Tx1 to Tx4 is covered with a first overcoat layer 74 for protecting and insulating the transparent conductive film 71. A metal bridge 73 is formed on the first overcoat layer 74 to electrically connect the transparent conductive films 72 of the detection electrodes Rx1 to Rx4. As the material of the metal bridge 73, molybdenum having high permeability is used as in the case of ITO used for the transparent conductive films 71 and 72.

  Further, the transparent conductive film 72 and the metal bridge 73 of the detection electrodes Rx1 to Rx4 are covered with a second overcoat layer 75 for protecting and insulating the transparent conductive film 72 and the metal bridge 73. The first overcoat layer 74 and the second overcoat layer 75 are both formed of a transparent insulating material.

  FIG. 7 is an explanatory diagram showing a state of touch sensing. FIG. 7A shows a state in which a user's finger is touching a part of touch panel 52 (on Rx1). FIG. 7B shows a comparative example of voltage peaks. In the figure, the horizontal axis represents time, and the vertical axis represents amplitude.

  As shown in FIG. 7A, the touch panel control unit 51 applies a driving pulse 81 as a scanning signal in the order of the scanning electrodes Tx1 to Tx4. Then, the touch panel control unit 51 analyzes the characteristics of the waveforms of the reception pulses 82 and 83 taken in the order of the detection electrodes Rx1 to Rx4.

  For example, when the drive pulse 81 is applied from the scan electrode Tx1, the detection electrode Rx2 is not affected by the parasitic capacitance (pseudo capacitor) due to the finger touch in the first state where the finger is not touched. Therefore, the detection signal acquisition unit 51b receives the reception pulse 83 having a waveform with a high voltage peak. Thus, the received pulse 83 having a waveform with a high voltage peak becomes an initial detection waveform in the touch panel 52.

  On the other hand, in the second state where the finger is touched, the detection electrode Rx1 is affected by the parasitic capacitance due to the finger touch. Therefore, the detection signal acquisition unit 51b receives the reception pulse 82 having a waveform with a low voltage peak. This is because the voltage peak is lowered due to the fact that the stored parasitic capacitance is increased by the touch of the finger.

  As illustrated in FIG. 7B, the difference between the reception pulse 83 having a waveform with a high voltage peak and the reception pulse 82 having a waveform with a low voltage peak is represented as a parasitic capacitance ΔC caused by the finger touching the touch panel 52. In this way, the touch panel 52 can detect a voltage peak reflecting a change in parasitic capacitance due to a finger touch.

  FIG. 8 is an explanatory diagram showing how the touch panel 52 changes over time. FIG. 8A shows an example of the waveform of the reception pulse 84 in the initial state, and FIG. 8B shows an example of the waveform of the reception pulse 85 in a state of deterioration with time.

  As shown in FIG. 8A, the voltage of the scanning signal (drive pulse 81) is sequentially input to the scanning electrodes Tx1 to Tx4 for each scanning period. On the other hand, the waveform of the detection signal detected by the detection electrodes Rx1 to Rx4 changes in synchronization with the voltage input of the scanning signal. The scanning signal drive pulses 81 sequentially input for each detection period with respect to the scanning electrodes Tx1 to Tx4 are a plurality of pulse trains, and the detection signal reception pulses 85 detected by the detection electrodes Rx1 to Rx4 are also included. It is a plurality of pulse trains.

For this reason, for example, in the touch panel 52 in the initial state at the time of factory shipment, the voltage peak of the reception pulse 84 detected by the detection electrodes Rx1 to Rx4 is sufficiently high due to the drive pulse 81 applied to the scan electrodes Tx1 to Tx4.
However, as shown in FIG. 8B, when the touch panel 52 changes with time, even if the drive pulse 81 is applied to the scan electrodes Tx1 to Tx4, the voltage peak of the reception pulse 85 detected by the detection electrodes Rx1 to Rx4 becomes low. .

  Since the material used for the metal bridge 73 (FIG. 5) changes with time due to humidity (moisture penetration), it is known that the DC resistance value of the metal bridge 73 changes with time to a high resistance. In product devices used in a certain humidity environment, measures are taken to prevent moisture penetration around the touch panel 52. However, even if such measures are taken, it is difficult to suppress the temporal change of the DC resistance value of the metal bridge 73, and the electrical characteristics of the metal bridge 73 are different from the initial state at the time when the touch panel 52 is manufactured. Come. For this reason, conventionally, correction processing of parameters used for detection has been required. For example, in Patent Document 2 described above, when the difference value between the detection signal when the V1 drive signal is input and the detection signal when the V2 drive signal is input is equal to or less than a predetermined threshold value, It has been proposed to correct the sensitivity by changing at least one parameter of the detection signal. However, in such a method, as described above, since it took time to detect the touch position, a more useful method has been studied.

<Description of touch position detection method>
The touch position detection method of the display device 41 with a touch panel according to the present embodiment will be described below.
First, the state transition of the image forming apparatus main body 2 will be described.
FIG. 9 is a state transition diagram of the image forming apparatus main body 2.
FIG. 10 is a list showing the relationship between the MFP state transition transition trigger and the transition state of the image forming apparatus main body 2. Transition numbers (1) to (10) shown in FIG. 9 correspond to the transition numbers shown in FIG.

First, the MFP state of the image forming apparatus main body 2 will be described.
If the MFP state of the image forming apparatus main body 2 is the main power supply OFF state, the image forming apparatus main body 2 does not perform any processing.
If the MFP state is the standby state, the image forming apparatus body 2 can immediately start the printing process when there is an operation from the user, reception of a fax, or the like.
If the MFP state is the power saving state, the power consumption of the image forming apparatus main body 2 can be saved by displaying the display panel 54 in black.

  If the MFP state is the sub power OFF state, the image forming apparatus main body 2 can receive data and fax, but cannot read or print a document. However, the data and fax received by the image forming apparatus main body 2 when the sub power supply is OFF can be printed when the standby state is restored.

  If the MFP state is ErP auto power OFF, data and fax reception, document reading, and printing cannot be performed. The ErP auto power OFF is a state in which the power consumption during standby is reduced (for example, power consumption 0. 0), as indicated in the EU (European Union) standby power standard ErP directive (Eco-design requirements for energy related products). 5W or less). In the ErP auto power OFF state, it is possible to obtain a power saving effect higher than that in the sub power supply OFF state, which is close to the main power supply OFF state.

The transition number and MFP state transition will be described below.
The transition number (1) indicates that the MFP state of the image forming apparatus main body 2 transitions from the main power supply OFF state to the standby state when the user turns on the main power switch 48. At this time, a buzzer sound is emitted.
The transition number (2) indicates that the MFP state transitions from the power saving state to the standby state when the user presses the power key 42 for a short time. At this time, a buzzer sound is emitted.

The transition number (3) indicates that the MFP state shifts from the standby state to the power saving state according to the set time (for example, 5 minutes) of the timer counted by the control unit 30.
The transition number (3) also indicates that the MFP state transitions from the standby state to the power saving state when the user presses the power key 42 for a short time. At this time, a response buzzer sound in response to the user pressing the power key 42 for a short time is emitted.

The transition number (4) indicates that the MFP state transitions from the ErP auto power OFF state to the standby state when the user presses the power key 42 for a short time. In the figure, the ErP auto power OFF state is represented as “ErP OFF”.
The transition number (4) indicates that the MFP state transitions from the ErP auto power OFF state to the standby state according to the set time of the timer.

Transition number (5) indicates that the MFP state transitions from the standby state to the ErP auto power OFF state according to the set time of the timer.
The transition number (6) indicates that the MFP state transitions from the standby state to the sub power source OFF state when the user presses the power key 42 for a long time. At this time, a response buzzer sound in response to a long press of the power key 42 by the user is emitted.
The transition number (7) indicates that the MFP state transitions from the sub power supply OFF state to the standby state when the user presses the power key 42 for a short time. At this time, a buzzer sound is emitted.

The transition number (8) indicates that the MFP state transitions from the power saving state to the ErP auto power OFF state according to the set time of the timer.
The transition number (9) indicates that the MFP state transitions from the sub power supply OFF state to the ErP auto power OFF state according to the set time of the timer.
The transition number (10) indicates that the MFP state transitions from the power saving state to the sub power source OFF state when the user presses the power key 42 for a long time. At this time, a response buzzer sound in response to a long press of the power key 42 by the user is emitted.

  As described above, the MFP state transitions from the main power supply OFF state, the power saving state, the sub power supply OFF state, and the ErP auto power OFF state based on a predetermined condition. Here, the MFP state in which the display panel 54 is displayed in black is the ErP auto power OFF state indicated by the transition numbers (5), (8), and (9), and the sub-state indicated by the transition numbers (6) and (10). Either the power is OFF or the power saving state is indicated by the transition number (3). When the MFP state shifts to one of the ErP auto power OFF state, the sub power supply OFF state, and the power saving state, the first state detection data based on the initial detection waveform of the touch panel 52 is stored in the first state storage unit 32a. The

  In particular, in the ErP auto power OFF state, it is considered that the standby power of the image forming apparatus main body 2 is the smallest and no touch operation is performed by the user. Therefore, when the MFP state shifts to the ErP auto power OFF state indicated by the transition numbers (5), (8), and (9), the first state detection data based on the initial detection waveform of the touch panel 52 is stored in the first state. It is desirable to store in the part 32a.

Next, a position detection method on the touch panel 52 will be described.
FIG. 11 is a flowchart illustrating an example of a method of collecting the first state detection data in the first state where the touch operation is not performed.

  First, when the MFP state of the image forming apparatus main body 2 shifts to one of the ErP auto power OFF state, the sub power supply OFF state, and the power saving state (S1), the display panel 54 is displayed in black (S2).

  Next, the scanning signal supply unit 51a shown in FIG. 4 prepares the scanning signal Tx (X = 1) (S3), and outputs the scanning signal Tx (X) to the touch panel 52 (S4). Here, the subscript X is a variable used as a scanning control factor, and takes a value from “1” to “N”. N is the total number of detection electrodes, and N = 4 in the example shown in FIG.

  When receiving the detection signal Rx (X) from the touch panel 52, the detection signal acquisition unit 51b stores the first state detection data of the detection signal Rx (X) in the first state storage unit 32a (S5). The detection signal Rx (X) represents a detection signal that the detection signal acquisition unit 51b receives from the touch panel 52 in the first state.

  Next, the detection signal acquisition unit 51b determines whether or not the subscript X is less than N (S6). If the subscript X is less than N (YES in S6), the scanning signal supply unit 51a and the detection signal acquisition unit 51b add “1” to the subscript X (S8), and repeat the processing from step S4 onward. .

  When the subscript X becomes N or more (NO in S6), the detection signal acquisition unit 51b receives the detection signal Rx (X) from the touch panel 52 and the detection signal Rx (X ) In which the first state detection data is stored (S7), and the present process is terminated.

  FIG. 12 is a flowchart illustrating an example of a method for collecting second state detection data in the second state in which the touch operation is being performed.

  First, when the MFP state of the image forming apparatus main body 2 shifts to a standby state other than the ErP auto power OFF state, the sub power supply OFF state, and the power saving state (S11), the display panel 54 performs normal display (display modes other than black display). )

Next, the scanning signal supply unit 51a prepares the scanning signal Tx (X = 1) (S12), and outputs the scanning signal Tx (X) to the touch panel 52 (S13).
When receiving the detection signal RRx (X) from the touch panel 52, the detection signal acquisition unit 51b stores the second state detection data of the detection signal RRx (X) in the second state storage unit 32b (S14). The detection signal RRx (X) represents a detection signal that the detection signal acquisition unit 51b receives from the touch panel 52 in the second state.

  Next, the touch position detection unit 51c reads the first state detection data from the first state storage unit 32a (S15). Then, the touch position detection unit 51c determines whether or not the difference value between the first state detection data and the second state detection data is equal to or less than a threshold value (S16). The difference value between the first state detection data and the second state detection data corresponds to the difference voltage between the detection signal Rx (X) and the detection signal RRx (X), and the threshold corresponds to the threshold voltage compared with the difference voltage.

  When the difference value between the first state detection data and the second state detection data exceeds the threshold (NO in S16), the touch position detection unit 51c determines that the part indicated by the detection signal RRx (X) is the touch unit (S17). ). On the other hand, when the difference value between the first state detection data and the second state detection data is equal to or less than the threshold (YES in S16), the touch position detection unit 51c determines that the part indicated by the detection signal RRx (X) is a non-touch part. Determine (S18).

  Next, the touch position detection unit 51c determines whether or not the subscript X is less than N (S19). When the subscript X is greater than or equal to N (NO in S19), the detection signal acquisition unit 51b receives the detection signal RRx (X) from the touch panel 52, and the second state storage unit 32b receives the detection signal RRx (X ) To store the second state detection data of () is stopped (S20). Then, the touch position detection unit 51c performs a coordinate calculation process, extracts a touch position 92 from a detection position candidate 91 (touch part) shown in FIG. 13 to be described later (S21), and ends this process.

  On the other hand, when the subscript X is less than N (YES in S19), the scanning signal supply unit 51a, the detection signal acquisition unit 51b, and the touch position detection unit 51c add “1” to the subscript X (S22). The processing after step S13 is repeated again.

  FIG. 13 is an explanatory diagram illustrating an example of the first state detection data and the second state detection data in the sensor unit of the touch panel 52. Here, the sensor unit represents a point where the scanning electrode and the detection electrode intersect. That is, the part where the number is described corresponds to the sensor unit.

  As shown in FIG. 13A, in the first state where the touch panel 52 is not touched, the first state detection data in each sensor unit of the touch panel 52 is “20”.

  As shown in FIG. 13B, in the second state in which the touch panel 52 is touched, in each sensor unit of the touch panel 52, the portion where the second state detection data is the same “20” as the first state detection data is determined as a non-touch portion. The On the other hand, a location where the second state detection data is greater than “20” is determined as a touch portion.

  Here, for example, the touch position detection unit 51c determines, as the detection position candidate 91, a portion where the difference value between the first state detection data and the second state detection data is larger than “50”. The highest second state detection data among the detection position candidates 91 is “178”, and this second state detection data is at the touch position 92. For this reason, the touch position detection unit 51c performs a coordinate calculation process to detect the touch position 92.

  In the display device with a touch panel 41 according to the embodiment described above, even if the electrode pattern of the touch panel 52 (particularly, the metal bridge 73) changes with time in high resistance and the voltage peak of the detection signal decreases, the first By acquiring the state detection data and the second state detection data, the influence of the voltage drop is offset. And the touch position detection part 51c can extract a touch position reliably based on the difference of the difference value of 1st state detection data and 2nd state detection data, and a threshold value. At this time, the touch position detection unit 51c does not perform the process of correcting the detection sensitivity as in the related art. In addition, the detection signal acquisition unit 51b does not perform processing that causes the touch responsiveness to deteriorate, such as increasing the acquisition time of the detection signal or increasing the number of acquisitions. For this reason, touch responsiveness can be maintained favorable.

  Further, it is not necessary to increase the voltage of the scanning signal, and a new booster circuit may not be added to the display device 41 with a touch panel. For this reason, an increase in circuit cost of the display device 41 with a touch panel can be suppressed.

[Modification]
The first state detection data may be updated according to the apparatus usage time of the image forming apparatus main body 2. The apparatus use time is a time during which the image forming apparatus main body 2 is used, but also includes a time during which the display panel 54 is not energized. For example, the first state detection data is updated when the device usage time has passed half a year or one year.

  Further, when the display panel 54 is in a standby state in which black display is not performed, the display panel 54 and the touch panel 52 are energized. The electrical characteristics of the scan electrode and the detection electrode gradually change with time according to the cumulative energization time. Therefore, the touch position detection unit 51c changes a parameter for amplifying the difference value between the first state detection data and the second state detection data according to the accumulated energization time obtained by accumulating the time when the touch panel 52 is energized. Is possible. As a result, the difference value that has become smaller can be amplified and compared with a threshold value.

  In addition, the touch position detection unit 51 c can obtain a finer touch position than the sensor unit of the touch panel 52 based on the dot size of the display panel 54.

  In the embodiment described above, the display device with a touch panel 41 has been described as being attached to the image forming apparatus body 2, but may be removable from the image forming apparatus body 2. Moreover, you may provide the display apparatus 41 with a touch panel in a smart phone, a tablet terminal, etc.

Further, the present invention is not limited to the above-described embodiments, and various other application examples and modifications can be taken without departing from the gist of the present invention described in the claims.
For example, the above-described embodiments are detailed and specific configurations of the apparatus and the system in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, it is possible to replace a part of the configuration of the embodiment described here with the configuration of another embodiment, and further, the configuration of another embodiment is replaced with the configuration of another embodiment. It is also possible to add. Moreover, it is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.
Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image forming apparatus main body, 5 ... Operation part, 20 ... Image forming part, 32 ... RAM, 32a ... 1st state memory | storage part, 32b ... 2nd state memory | storage part, 41 ... Display apparatus with a touch panel 51 ... Touch panel control unit 51a ... Scanning signal supply unit 51b ... Detection signal acquisition unit 51c ... Touch position detection unit 52 ... Touch panel 53 ... Display control circuit 54 ... Display panel

Claims (7)

An image forming apparatus main body and a display device,
The image forming apparatus main body includes an image forming unit that performs an image forming process based on an instruction through the display device,
The display device
A display panel for displaying images,
A touch panel superimposed on the display panel;
A plurality of scan electrodes formed on the touch panel;
A plurality of detection electrodes formed on the touch panel and intersecting the plurality of scanning electrodes;
A scanning signal supply unit for supplying a scanning signal to the plurality of scanning electrodes;
First state detection data based on detection signals acquired from the plurality of detection electrodes in a first state where the touch on the touch panel is not performed is stored in the first state storage unit, and the touch on the touch panel is performed. A detection signal acquisition unit that stores second state detection data based on detection signals acquired from the plurality of detection electrodes in the second state in a second state storage unit;
Touch the position of the touch panel in which a difference value obtained from the first state detection data read from the first state storage unit and the second state detection data read from the second state storage unit is equal to or greater than a predetermined threshold. An image forming apparatus comprising: a touch position detection unit that detects the position. The first state detection data is stored in the first state storage unit by the detection signal acquisition unit when the image forming apparatus main body shifts from a standby state to a power saving state or a stopped state and the display panel is displayed in black. Remembered,
The image forming apparatus according to claim 1, wherein the second state detection data is stored in the second state storage unit by the detection signal acquisition unit when the image forming apparatus main body is in a standby state. The image forming apparatus according to claim 2, wherein the first state detection data stored in the first state storage unit is updated by the latest first state detection data acquired by the detection signal acquisition unit. The image forming apparatus according to claim 2, wherein the first state detection data is updated according to an apparatus usage time of the image forming apparatus main body. The image according to any one of claims 1 to 4, wherein the touch position detection unit changes a parameter for amplifying the difference value according to a cumulative energization time obtained by accumulating the time during which the touch panel is energized. Forming equipment. A display panel for displaying images,
A touch panel superimposed on the display panel;
A plurality of scan electrodes formed on the touch panel;
A plurality of detection electrodes formed on the touch panel and intersecting the plurality of scanning electrodes;
A scanning signal supply unit for supplying a scanning signal to the plurality of scanning electrodes;
First state detection data based on detection signals acquired from the plurality of detection electrodes in a first state where the touch on the touch panel is not performed is stored in the first state storage unit, and the touch on the touch panel is performed. A detection signal acquisition unit that stores second state detection data based on detection signals acquired from the plurality of detection electrodes in the second state in a second state storage unit;
Touch the position of the touch panel in which a difference value obtained from the first state detection data read from the first state storage unit and the second state detection data read from the second state storage unit is equal to or greater than a predetermined threshold. A touch position detecting unit that detects the position as a position. A display panel for displaying images,
A touch panel superimposed on the display panel;
A plurality of scan electrodes formed on the touch panel;
A touch position detection method for a display device, comprising: a plurality of detection electrodes formed on the touch panel and intersecting with the plurality of scan electrodes,
Supplying a scanning signal to the plurality of scanning electrodes;
Storing in the first state storage unit first state detection data based on detection signals acquired from the plurality of detection electrodes in a first state where the touch on the touch panel is not performed;
Storing in the second state storage unit second state detection data based on detection signals acquired from the plurality of detection electrodes in a second state where the touch on the touch panel is performed;
Touch the position of the touch panel in which a difference value obtained from the first state detection data read from the first state storage unit and the second state detection data read from the second state storage unit is equal to or greater than a predetermined threshold. Detecting the position as a position.

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