JP2013195910A - Image forming apparatus and electronic instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to display an image, such as a figure, input by a user and extract data of the image to the outside.SOLUTION: An image forming apparatus has the configuration in which bistable liquid crystal is sandwiched between first and second electrodes. In an initial state, the entire screen is made uniformly dark by applying a refresh voltage to each of the first and second electrodes, thereby bringing the liquid crystal into a focal conic state. When a figure or the like is drawn with a stylus pen, the liquid crystal of the drawn portion changes from the focal conic state to a planar state, with the result that only the drawn portion increases in reflectance and is shown brightly. In the position where the stylus pen is pushed down, a projecting portion is pressed, with the result that the first and second electrodes contact, making it possible to output coordinates in the contact position. At that time, the first and second electrodes are driven at a voltage lower than the lower limit threshold in the range of voltage applied to liquid crystal, at which the liquid crystal can change the molecule arrangement thereof.

Description

  The present disclosure relates to an image forming apparatus and an electronic apparatus, and in particular, a pressure-sensitive rewritable image forming apparatus and an electronic apparatus that can write down a handwritten character or figure using a finger or a stylus pen like a notepad. About.

  In addition to the function of displaying an image based on image data, a display device such as electronic paper has a function of displaying contents drawn by a user (see, for example, Patent Document 1). The latter function allows the user to trace the surface of the display area of the display device with a stylus pen, and draws desired characters and figures in the display area. The image information is displayed without power supply. Can continue to do.

  For such an image, drawing data traced by the stylus pen is stored in a memory, and is displayed so as to be superimposed on the original image. As a result, the user can view the original image together with the memo drawn by the user.

JP 2009-123152 A

  However, with the conventional technology, data such as graphics input by the user can be displayed and left, but there is a problem that the data cannot be taken out to the outside.

  The present disclosure has been made in view of the above points, and an object thereof is to provide an image forming apparatus and an electronic apparatus that can display data such as a graphic input by a user and can extract the data to the outside.

  In order to solve the above-described problem, an image forming apparatus uses bistable liquid crystal, first and second electrodes sandwiching the liquid crystal, and coordinate data of a position subjected to external pressure as the first and first electrodes. And a data detection unit that extracts the first and second electrodes at a voltage lower than a lower limit threshold value of a liquid crystal application voltage range in which the liquid crystal can change a molecular arrangement state thereof. Drive.

  In order to solve the above-described problem, the electronic apparatus uses bistable liquid crystal, first and second electrodes sandwiching the liquid crystal, and coordinate data of a position subjected to external pressure as the first and second electrodes. A data detection unit that extracts from the second electrode, and the data detection unit has a voltage lower than a lower limit threshold value of a liquid crystal applied voltage range in which the liquid crystal can change a molecular arrangement state thereof. An image forming apparatus for driving the electrodes is provided.

  The image forming apparatus and the electronic apparatus having the above-described configuration can display image data such as a figure input by the user and take it out to the outside.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to a first embodiment. FIG. 3 is a cross-sectional view illustrating a molecular arrangement state when the image forming apparatus according to the first embodiment receives external pressure. It is a figure explaining the bistability of a liquid crystal, (A) is a planar state, (B) is a focal conic state, (C) has shown the homeotropic state. It is a figure which shows the voltage-reflectance characteristic of a liquid crystal. It is a figure explaining the operation | movement principle of a resistive touch panel, Comprising: (A) is a figure which shows the electrical connection of a resistive touch panel, (B) is an electrical equivalent circuit schematic of a resistive touch panel. It is a figure which shows the voltage-reflectance characteristic of the liquid crystal of an image forming apparatus. 1 is an external view illustrating an example of an electronic apparatus having an image forming apparatus according to a first embodiment. It is a figure which shows the structure of the electrode of the image forming apparatus which concerns on 2nd Embodiment. FIG. 9 is an operation explanatory diagram of the image forming apparatus according to the second embodiment, where (A) shows display and detection, and (B) shows display reproduction. It is explanatory drawing of the applied voltage to a liquid crystal and an electrode. FIG. 9 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to a third embodiment, where (A) is an initial state of the image forming apparatus, (B) is a data input to the image forming apparatus, and (C) is an image It shows the data detection time of the forming apparatus. FIG. 9 is an operation explanatory diagram of the image forming apparatus according to the third embodiment, where (A) shows data input, (B) shows data detection, and (C) shows display reproduction.

  Hereinafter, embodiments of the present technology will be described in detail with reference to the drawings.

  FIG. 1 is a sectional view showing a schematic configuration of an image forming apparatus according to the first embodiment, and FIG. 2 is a sectional view showing a molecular arrangement state when the image forming apparatus according to the first embodiment is subjected to external pressure. It is.

  The image forming apparatus 10 according to the first embodiment of the present disclosure has a stacked configuration in which a bistable liquid crystal 11 is sandwiched between two conductive electrodes 12 and 13 as shown in FIG. The portion including the liquid crystal 11 has a plate shape as a whole. A film base 14 is disposed on the side where the electrode 12 is provided, and a plurality of convex portions 15 are formed on the surface of the film base 14 on the liquid crystal 11 side. The electrode 12 is formed so as to cover the entire surface of the film substrate 14 including all the convex portions 15. On the other hand, the film base 16 is disposed on the side where the electrode 13 is present. A light absorption layer 17 and an electrode 13 are laminated on the entire surface of the film substrate 16 on the liquid crystal 11 side.

  The liquid crystal 11 is filled in a space surrounded by the electrode 12 and the electrode 13 and the sealing material 18 disposed between the electrode 12 and the electrode 13, and the interval between the electrode 12 and the electrode 13 is It is kept constant by a separator 19 disposed in a space filled with the liquid crystal 11. The electrodes 12 and 13 are connected to voltage sources 20 and 21 for setting the molecular alignment state of the liquid crystal 11 to a predetermined state. Further, when detecting a portion where the molecular arrangement state of the liquid crystal 11 is changed, another voltage source and a coordinate detector are connected instead of the voltage sources 20 and 21. In the present embodiment, the convex portion 15 is formed on the electrode 12 side, but may be formed on the electrode 13 side, or may be formed on both the electrode 12 and the electrode 13. Good.

  The liquid crystal 11 has bistability or memory properties and can be, for example, a cholesteric liquid crystal. The film bases 14 and 16 have flexibility, and can be, for example, PET (Polyethylene Terephthalate). The electrode 12 and the electrode 13 are transparent conductive films made of, for example, ITO (Indium Tin Oxide). The convex portion 15 is bonded to the film base material 14 or formed integrally with the film base material 14. The separator 19 is formed of an elastic resin ball.

  In the image forming apparatus 10, when the molecular arrangement of the liquid crystal 11 is spiral in the direction of the surfaces of the film bases 14 and 16 as shown in FIG. Since it passes through and reaches the light absorption layer 17, it is uniformly dark screen display. Here, as shown in FIG. 2, for example, when the surface of the film substrate 14 is pressed down with the tip of the stylus pen 23, the portion of the liquid crystal 11 that has been subjected to external pressure changes the molecular arrangement of the liquid crystal 11. The external light 22 is reflected to form an image that looks like a bright image. Further, when the stylus pen 23 presses down the surface of the film base material 14, the convex portion 15 immediately below it moves to the electrode 13 side and comes into contact with the electrode 13. The coordinates of the convex portion 15 in contact with the electrode 13 can be detected by connecting an appropriate voltage source and a coordinate detection unit to the electrode 12 and the electrode 13. Hereinafter, the principle that the image forming apparatus 10 forms an image and the principle of detecting the coordinates of the formed image will be described.

  3A and 3B are diagrams illustrating the bistability of the liquid crystal, where FIG. 4A shows the planar state, FIG. 3B shows the focal conic state, FIG. 4C shows the homeotropic state, and FIG. It is a figure which shows a reflectance characteristic. In FIG. 4, the horizontal axis indicates the voltage applied to the electrodes 12 and 13, and the vertical axis indicates the change in reflectance with respect to the applied voltage.

  A cholesteric liquid crystal has a spiral structure in which rod-like liquid crystal molecules are stacked while rotating the molecular alignment little by little in the same rotation direction around the helical axis, and reflects light of a specific wavelength by the rotation pitch. Can do.

  When the cholesteric liquid crystal is sandwiched between the electrodes 12 and 13 parallel to each other, as shown in FIG. 3A, a planar state is obtained in which the helical axis is oriented in a direction perpendicular to the surfaces of the electrodes 12 and 13.

  Here, when a voltage is applied to the electrodes 12 and 13, the cholesteric liquid crystal transitions from the planar state to the focal conic state as shown in FIG. For example, in FIG. 4, when 20 volts, which is the minimum voltage (threshold value) for driving the cholesteric liquid crystal, is applied, the helical axis becomes parallel to the surfaces of the electrodes 12 and 13, and the cholesteric liquid crystal exhibits a focal conic state. Will become transparent. At this time, in the image forming apparatus 10, the light transmitted through the cholesteric liquid crystal in the focal conic state is absorbed by the light absorption layer 17 disposed between the electrode 13 and the film substrate 16, so that a dark image is formed. Will be generated and displayed.

  When a higher voltage, for example, a voltage of 30 volts, is applied to the electrodes 12 and 13, liquid crystal molecules are aligned in the direction of the electric field as shown in FIG. 3C, and the cholesteric liquid crystal exhibits a homeotropic state.

  Here, when the cholesteric liquid crystal is in the homeotropic state, when the voltage applied to the electrodes 12 and 13 is set to a low voltage (for example, 20 volts), the focal conic state is restored, and when the voltage is rapidly reduced to zero, the planar state is restored. This focal conic state corresponds to a refresh operation for clearing the drawn image in the image forming apparatus 10. On the other hand, in the planar state, only circularly polarized light that is the same as the direction of the spiral is reflected, and an overall bright image is generated.

  The cholesteric liquid crystal is stable in both the planar state and the focal conic state even when the voltage applied to the electrodes 12 and 13 is made zero and the electric field is removed, and maintains the planar state and the focal conic state, respectively. That is, the cholesteric liquid crystal has bistability in two stable states when no voltage is applied.

  Further, when the cholesteric liquid crystal is in a focal conic state when no voltage is applied, the cholesteric liquid crystal changes to a planar state when receiving external pressure. As shown in FIG. 2, when the surface of the image forming apparatus 10 is traced with the stylus pen 23, the traced portion changes from the focal conic state to the planar state, and the reflectance increases. This corresponds to the operation of generating a bright line drawing image.

  5A and 5B are diagrams for explaining the operation principle of the resistive touch panel, wherein FIG. 5A is a diagram showing electrical connection of the resistive touch panel, and FIG. 5B is an electrical equivalent circuit diagram of the resistive touch panel. FIG. 6 is a diagram showing the voltage-reflectance characteristics of the liquid crystal of the image forming apparatus.

  In the resistive touch panel, the electrodes 12 and 13 formed on the entire surface sandwiching the liquid crystal 11 are composed of resistive films 31 and 32, and the resistance of the resistive films 31 and 32 is used to make a stylus pen 23. Is used to detect the coordinates of the pressed position. As shown in FIG. 5A, the resistive film 31 has terminals 33 and 34 at both ends in the left-right direction in the figure, and detects the abscissa of the touch position pressed by the stylus pen 23. On the other hand, the resistance film 32 has terminals 35 and 36 at both ends in the vertical direction in the figure, and detects the ordinate of the touch position pressed by the stylus pen 23.

  Here, in order to simplify the description, a case where the ordinate of the pressed position of the stylus pen 23 is detected will be described. When detecting the ordinate, as shown in FIG. 5A, the terminals 33 and 34 of the resistive film 31 are connected together to one end of the coordinate detector 37, and the other end of the coordinate detector 37 is connected. Is connected to the terminal 36 of the resistance film 32. The terminal 35 of the resistance film 32 is connected to the positive terminal of the voltage source 38, and the terminal 36 is connected to the negative terminal of the voltage source 38.

  Here, it is assumed that the electrode 12 at the position of the convex portion 15 at the touch position (point A) is in contact with the electrode 13 by pressing the stylus pen 23. At this time, in terms of electrical circuit, as shown in FIG. 5B, the resistance film 32 has a resistance Rv1 connected in series between the terminal 35 and the terminal 36 with the point A as a connection point. , Rv2, and a voltage source 38 is connected to both ends of the series-connected resistors Rv1, Rv2. As for the resistive film 31, a resistor Rh1 between the terminal 33 and the point A and a resistor Rh2 between the terminal 34 and the point A are connected in parallel, and the connection point on the opposite side of the parallel connected point A Is connected to the coordinate detector 37.

  Here, if the input impedance of the coordinate detector 37 is sufficiently larger than (Rh1 + Rh2) / 2 which is the maximum value of the resistors Rh1 and Rh2 connected in parallel, the values of the resistors Rh1 and Rh2 are substantially Can be ignored. That is, the coordinate detector 37 directly measures the potential signal at point A obtained by dividing the voltage of the voltage source 38 by the resistors Rv1 and Rv2. In this way, the ordinate of the touch position pressed by the stylus pen 23 is detected.

  Based on the same principle, the abscissa of the touch position pressed by the stylus pen 23 can also be detected. That is, the detection of the abscissa changes the power supply of the voltage source 38 from the resistance film 32 to the resistance film 31, and the detection by the coordinate detector 37 changes from the resistance film 31 to the resistance film 32. By doing so, the abscissa of the touch position pressed by the stylus pen 23 is detected. Although the ordinate and abscissa are not shown in the drawing, semiconductor switches are provided for the terminals 33 and 34 of the resistive film 31 and the terminals 35 and 36 of the resistive film 32, respectively, and are switched at appropriate cycles. It can be detected alternately.

  The voltage source 38 uses a voltage in a range different from the voltage range of the voltage sources 20 and 21 used to change the molecular alignment state of the liquid crystal 11. For example, as shown in FIG. 6, when the voltage range applied to the cholesteric liquid crystal is 20 to 40 volts, the voltage source 38 used for coordinate detection is more than 20 volts, which is the lower threshold of the liquid crystal applied voltage range. It has a low touch drive voltage range of about 5 to 10 volts. Preferably, the voltage of the voltage source 38 is 5 volts so as not to interfere with the operation of the liquid crystal 11.

  FIG. 7 is an external view showing an example of an electronic apparatus having the image forming apparatus according to the first embodiment.

  This electronic device 40 is a plate-like pressure-sensitive handwritten notepad provided with the image forming apparatus 10 shown in FIG. The electronic device 40 also includes a refresh button 41 for erasing the line drawing drawn on the image forming apparatus 10 and a data button 42 for instructing whether or not to extract coordinates detected by the touch panel as input data by the stylus pen 23. Yes. The input data is stored in the built-in memory, and preferably can be taken out by using a built-in wireless function or by writing to a memory card via a built-in memory card reader / writer.

  In the image forming apparatus 10, when the liquid crystal 11 is in the focal conic state after the refresh operation, the external light is hardly reflected and is absorbed by the light absorption layer 17, thereby displaying a dark display. When handwritten input is performed on the surface of the image forming apparatus 10 with the stylus pen 23, the portion senses and reflects, and the line drawing as input by handwriting remains bright and displayed. The coordinate data of the portion input by the stylus pen 23 is sequentially stored in the built-in memory at the time of input, and when a data button 42 is pressed, for example, a display storage unit such as a memory card, and further a personal computer Is output to an external device.

  FIG. 8 is a diagram illustrating the configuration of the electrodes of the image forming apparatus according to the second embodiment. FIG. 9 is an operation explanatory diagram of the image forming apparatus according to the second embodiment. At the time of detection, (B) shows the display reproduction time, and FIG.

  The image forming apparatus according to the second embodiment is different from the image forming apparatus 10 according to the first embodiment by changing the configuration of the electrodes 12 and 13 formed on the film bases 14 and 16. Yes. That is, as shown in FIG. 8, the electrodes 12 and 13 are each formed in a strip pattern and are installed with their length directions orthogonal to each other. In the electrode 12 of the film base material 14, one row of convex portions 15 is arranged in one pattern, and in the electrode 13 of the film base material 16, one pattern is arranged in an array of convex portions 15 arranged in a line. Correspondingly arranged. In the illustrated example, the striped electrodes 12 and 13 are conceptually shown with a reduced number of them, but in reality, the number of the electrodes 12 and 13 is increased to increase the resolution of the drawn image. doing.

  By configuring the electrodes 12 and 13 as shown in FIG. 8, a touch panel of a matrix switch can be configured. In this touch panel, since the data detection unit can directly detect the coordinates of the touch position pressed by the stylus pen 23, an analog processing circuit such as the coordinate detector 37 becomes unnecessary, and the position information of the detected coordinates is directly stored in the memory. It can be memorized.

  In the image forming apparatus according to the second embodiment, since the electrodes 12 and 13 have a matrix switch configuration, in addition to data input by image drawing by the stylus pen 23, stored external data is captured and displayed. It can also function as a display device.

  In data input, as shown in FIG. 9A, the image forming apparatus 10a according to the second embodiment is connected to the display storage unit 10b and displays the input data by itself. And can be detected and stored in the display storage unit 10b. Here, the display storage unit 10b is provided independently of the image forming apparatus 10a. However, the display storage unit 10b is built in the image forming apparatus 10a or is detachable from the image forming apparatus 10a. Also good.

  As shown in FIG. 2, the display of the input data by the image forming apparatus 10a is performed by changing the cholesteric liquid crystal partly from the focal conic state to the planar state by pressing the stylus pen 23, so that only that part is reflected. Is equivalent to changing. The data input to the image forming apparatus 10a is detected by pressing the stylus pen 23 so that the electrode 12 of the convex portion 15 at that position comes into contact with the opposed strip-shaped electrode 13 and the coordinates of the position are detected. It corresponds to doing. In the present embodiment, since the display and detection of the input data are simultaneous, the detection data is stored in the display storage unit 10b at the same time.

  The data stored in the display storage unit 10b in this way can be further transferred to the external device 45 for use. Since the data stored in the display storage unit 10b is the coordinate data of the drawn image, the external device 45 can capture and edit the data as vector data.

  In order to reproduce the image stored in the display storage unit 10b, the stored data can be reproduced and displayed by returning the stored data to the image forming apparatus 10a as shown in FIG. 9B. This is realized by applying a predetermined voltage to the corresponding addresses of the electrodes 12 and 13 so as to change the focal conic state to the planar state only by the coordinates corresponding to the stored coordinates.

  As shown in FIG. 10, the molecular alignment state of the liquid crystal 11 is changed by changing the voltage applied to each of the electrodes 12 and 13 and thereby changing the electric field applied to the liquid crystal 11. That is, first, to set the image forming apparatus 10a to the initial state before drawing, for example, a voltage of -10 volts is applied to one of the electrode 12 and the electrode 13, and a voltage of 20 volts and 10 volts is applied to the other. , Then bring both to 0 volts. As a result, the liquid crystal 11 is sequentially changed into a homeotropic state and a focal conic state, is stabilized in the focal conic state, and is initialized to a dark display as a whole.

  At the time of data input, for example, a voltage of 5 volts is applied to one of the electrode 12 and the electrode 13, 10 volts is applied to the other, and a difference voltage of 5 volts is applied to the liquid crystal 11. This voltage is sufficiently lower than 20 volts, which is the lower limit threshold voltage of the liquid crystal applied voltage range, and the molecular alignment state of the liquid crystal 11 is not changed by this voltage.

  When reproducing the image stored in the display storage unit 10b, a voltage of -10 volts is applied to one selected address of the electrode 12 and the electrode 13 while a voltage of 20 volts is applied to the other selected address. Then both are at 0 volts. As a result, the liquid crystal 11 is cleared in a homeotropic state when a differential voltage of 30 volts is applied, and is stabilized in a planar state when the differential voltage becomes 0 volts. Bright display. By executing this for all the addresses of the electrode 12 and the electrode 13, the image stored in the display storage unit 10b is reproduced and displayed on the image forming apparatus 10a.

  FIG. 11 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to the third embodiment. FIG. 11A is an initial state of the image forming apparatus, FIG. ) Shows the data detection time of the image forming apparatus. 12A and 12B are diagrams for explaining the operation of the image forming apparatus according to the third embodiment. FIG. 12A shows data input, FIG. 12B shows data detection, and FIG. 12C shows display reproduction.

  The image forming apparatus 50 according to the third embodiment has a laminated structure in which a bistable liquid crystal 51 is sandwiched between two conductive electrodes 52 and 53 as shown in FIG. ing. The electrode 52 is formed on the surface of the film base 54 on the liquid crystal 51 side, the electrode 53 is formed on the surface of the film base 55 on the liquid crystal 51 side, and the electrodes 52 and 53 are strips as shown in FIG. And are arranged orthogonal to each other.

  In the image forming apparatus 50, a light absorption layer 56 is formed between the film base 55 and the electrode 53. The image forming apparatus 50 further includes a sealing material 57 for forming a sealed space filled with the liquid crystal 51 between the electrode 52 and the electrode 53, and a separator 58 for maintaining the thickness of the liquid crystal 51 constant. I have. A voltage source (not shown) for refreshing the screen of the image forming apparatus 50 is connected to the electrodes 52 and 53, and an output line 59 and a voltage for detecting the coordinates of the position pressed by the stylus pen 23 are connected. A source 60 is connected via switches 61 and 62.

  The image forming apparatus 50 is the same as that in the first and second embodiments regarding data input, but detects a change in capacitance when the molecular alignment state of the liquid crystal 51 is changed regarding data detection. Capacitance detection type touch panel. That is, in the initial state of the image forming apparatus 50, as shown in FIG. 11A, the liquid crystal 51 is in the focal conic state. As a result, the image forming apparatus 50 transmits the incident external light with almost no reflection, and absorbs it in the light absorption layer 56 to make the display dark.

  When an image is drawn with the stylus pen 23, as shown in FIG. 11B, the corresponding portion of the liquid crystal 51 pressed by the stylus pen 23 shifts from the focal conic state to the planar state. As a result, the corresponding portion becomes brighter by reflecting the incident external light, and the image forming apparatus 50 displays the drawn image and maintains the display.

  When detecting data such as a drawn figure, the voltage of the voltage source 60 is applied to the electrodes 52 and 53 to measure the dielectric constant of the liquid crystal 51 at the crossing position as shown in FIG. . Since the liquid crystal 51 exhibits anisotropy in the dielectric constant (which is a refractive index for light) depending on the molecular orientation, the difference between the dielectric constants distinguishes between the focal conic state and the planar state. . Dielectric constant measurements are sequentially scanned to detect the planar state at all intersection positions. The voltage source 60 used for measuring the dielectric constant is a voltage lower than the lower limit threshold of the liquid crystal applied voltage range in which the liquid crystal 51 can change its molecular alignment state.

  Since the image forming apparatus according to the third embodiment is the electrodes 52 and 53 having a matrix switch configuration, data input by drawing an image with the stylus pen 23, data detection and storage, and reproduction display of the stored data And has the function.

  In the data input, as shown in FIG. 12A, the image forming apparatus 50 receives data when a user draws a figure using the stylus pen 23 and simultaneously displays an image of the figure. .

  In the detection of input data, as shown in FIG. 12B, the image forming apparatus 50 is connected to the display storage unit 63, detects already input data, and displays the display storage unit 63. Can be memorized. The data stored in the display storage unit 63 can be further transferred to the external device 64.

  In order to reproduce the image stored in the display storage unit 63, the stored data can be reproduced and displayed by returning the stored data to the image forming apparatus 50, as shown in FIG. This is realized by performing control to apply a predetermined voltage to the corresponding addresses of the electrodes 52 and 53 so that only the coordinate portion corresponding to the stored coordinate is changed from the focal conic state to the planar state.

  DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 10a ... Image forming apparatus, 10b ... Display memory | storage part, 11 ... Liquid crystal, 12, 13 ... Electrode, 14 ... Film base material, 15 ... Convex part, 16 ... Film Base material 17... Light absorption layer 18. Sealing material 19 Separator 20 21 Voltage source 22 External light 23 Stylus pen 31 32 Resistance film 33 , 34, 35, 36 ... terminal, 37 ... coordinate detector, 38 ... voltage source, 40 ... electronic equipment, 41 ... refresh button, 42 ... data button, 45 ... external equipment, 50 ... Image forming apparatus, 51 ... liquid crystal, 52, 53 ... electrode, 54, 55 ... film base material, 56 ... light absorbing layer, 57 ... sealing material, 58 ... separator, 59 ... output line, 60 ... Voltage source, 61, 62 ... Switch, 63 ... Display memory 64 ...... external device

Claims (9)

A bistable liquid crystal,
First and second electrodes for sandwiching the liquid crystal;
A data detection unit for extracting data of coordinates of a position subjected to external pressure from the first and second electrodes;
And the data detection unit drives the first and second electrodes with a voltage lower than a lower threshold of a liquid crystal applied voltage range in which the liquid crystal can change its molecular arrangement state.   The image forming apparatus according to claim 1, wherein the liquid crystal is a cholesteric liquid crystal.   In the data detection section, the first and second resistance films formed as the first and second electrodes are partially in contact with the first and second resistance films at a position subjected to external pressure. The image forming apparatus according to claim 1, further comprising: a coordinate detector configured to detect coordinates of a position subjected to external pressure based on the potential signal detected in this way.   A plurality of protrusions for ensuring partial contact of the first and second resistance films at a position disposed on at least one of the first and second resistance films and subjected to external pressure. Item 4. The image forming apparatus according to Item 3.   The image forming apparatus according to claim 3, wherein the first and second resistance films are formed on an entire surface sandwiching the liquid crystal. The first and second electrodes are formed in a strip shape in a direction orthogonal to each other, sandwiching the liquid crystal,
The data detection unit includes a coordinate detector that detects the coordinates of the first and second electrodes at the crossing position that has been subjected to external pressure and that has received the external pressure by detecting the first and second electrodes. The image forming apparatus according to claim 1.   At least one of the first and second electrodes has a plurality of convex portions that are arranged in the length direction thereof and ensure contact between the first and second electrodes at a position where external pressure is applied. Item 7. The image forming apparatus according to Item 6. The first and second electrodes are formed in a strip shape in a direction orthogonal to each other, sandwiching the liquid crystal,
The data detecting unit sequentially scans the first and second electrodes to detect coordinates of a position subjected to external pressure based on a dielectric constant of the liquid crystal at a crossing position of the first and second electrodes. The image forming apparatus according to claim 1, further comprising a detector. A bistable liquid crystal,
First and second electrodes for sandwiching the liquid crystal;
A data detection unit for extracting data of coordinates of a position subjected to external pressure from the first and second electrodes;
The data detection unit includes an image forming apparatus that drives the first and second electrodes with a voltage lower than a lower threshold of a liquid crystal applied voltage range in which the liquid crystal can change its molecular arrangement state. Electronics.

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