JP2007218986A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of displaying an image of high quality in which changes in gradation and color tone of a liquid crystal layer at a depression position are suppressed even when a glass substrate is pressed. <P>SOLUTION: A pen input section 34 is arranged over a liquid crystal panel 10 to perform an input operation by pressing the liquid crystal panel 10 where an image is displayed with an input pen 43. A control section 36 corrects a driving voltage of a pixel in a region including the depression position in the center by adding a correction voltage pattern of a small area stored in a memory 37 thereto. Consequently, an image display state of the liquid crystal panel 10 which is pressed can be put closer to an image display state of the liquid crystal panel which is not pressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device that reduces the degree to which image display at a pressed position is disturbed when an image display surface is pressed.

  A finger input device that performs an input operation by directly touching the surface of an image-displayed liquid crystal display has been put into practical use. According to the finger input device, various types of combinations such as an image button and an image volume can be realized using one liquid crystal display.

  Pen input devices that perform computer operations by bringing the tip of an input pen into contact with the surface of a liquid crystal display have also been put into practical use. Some pen input devices can indicate a smaller area on the liquid crystal display with higher positional accuracy than a finger input device, and some detect the pressing force of the pen tip together with the pressing position.

  Patent Document 1 discloses a pen input device that detects a radio wave transmitted from the tip of an input pen by arranging a large number of loop antennas on a panel surface for operating the input pen. The X and Y coordinates of the pressing position are obtained by specifying the X direction loop antenna and the Y direction loop antenna that maximize the detection output of the radio wave.

  Patent Document 2 discloses a pen input device in which a pressing force detection mechanism is incorporated in an input pen for performing position detection using a loop antenna. The tip of the input pen is moved in and out according to the pressing force, and the input pen performs radio wave output in which the frequency is changed according to the pressing force.

  A general liquid crystal display has a liquid crystal substance filled in a very narrow gap of 5 to 10 μm formed between a pair of glass substrates. By changing the voltage applied to the transparent electrode for each pixel formed on the pair of glass substrates to control the amount of birefringence of the liquid crystal substance, the amount of light passing through the polarizing plate superimposed on the glass substrate is changed.

  Since the birefringence amount of the liquid crystal layer changes according to the thickness of the liquid crystal layer, when the glass substrate is pressed and the liquid crystal layer becomes thin, the display gradation (transmitted light amount) at the pressed position changes. Further, since the birefringence amount of the liquid crystal layer changes depending on the tilt angle of the liquid crystal molecules, when the glass substrate is deformed and the tilt angle of the liquid crystal molecules changes, the display gradation of the deformation position changes.

  Patent Document 3 discloses a finger input device in which the display gradation of the pressed position of the liquid crystal display does not change even when the glass substrate is pressed. Here, a spacer is arranged around a glass substrate on the observation side of the liquid crystal display, and a transparent input substrate as another member is arranged on the spacer. That is, the pressing force of the input substrate is not transmitted to the glass substrate.

  By the way, a hybrid color liquid crystal display device has been proposed in which one pixel is constituted by two adjacent display units (sub-pixels) of the liquid crystal display to realize almost full color display. The hybrid color liquid crystal display device can display a high-definition image as compared with the conventional RGB color liquid crystal display device, and can display an image that is 30 to 50% brighter by the same illumination light.

  Patent Document 4 shows a hybrid color liquid crystal display device. Here, a green color filter is arranged in one display unit to display green, and in the other display unit, the birefringence of the liquid crystal layer is controlled in the chromatic color region to display red and blue. ing.

  Patent Document 5 discloses a resistance wire film type finger input device.

JP-A-63-70326 Japanese Patent No. 2602878 JP-A-6-301017 JP 2004-258616 A JP-A-5-242759

  In a finger input device and pen input device using a liquid crystal display, when a glass substrate on the observation side of the liquid crystal layer is pressed, the deflection state of light passing through the liquid crystal layer changes. As the liquid crystal layer at the pressing position becomes thinner, the deformation of the glass substrate at the pressing position changes the tilt angle of the liquid crystal molecules, and the gradation of the image display in the region centered on the pressing position changes. At the pressing position, the birefringence amount deviates from the birefringence amount assumed from the driving voltage applied to the liquid crystal layer. For this reason, the gradation of the liquid crystal layer observed through the deflecting plate is partially changed, and the quality of image display is lowered.

  In particular, when the pixel is displayed in color by controlling the birefringence amount of the liquid crystal layer in the chromatic color region, the pixel in the region centered on the pressed position causes both a density change and a color tone change. Changes in image display are conspicuous.

  In particular, when an input operation corresponding to the pressing force is performed by detecting the pressing force of the input pen, a large stress is generated in a small area where the pen tip comes into contact with the intentional pressing, thereby changing the image display.

  An object of the present invention is to provide a liquid crystal display device capable of displaying a high-quality image by suppressing a change in gradation and color tone of a liquid crystal layer at a pressed position even when a glass substrate is pressed.

  The present invention provides a pair of substrate members disposed with a liquid crystal layer interposed therebetween, electrode means disposed on the pair of substrate members and capable of applying a driving voltage to the liquid crystal layer for each display unit, and the electrode means Drive means for applying a drive voltage for each display unit to display an image. And the position detection means which detects the press position on the said board | substrate member is provided, and the said drive means adjusts the said drive voltage in the detected said press position in the direction which approaches the display state which is not pressed.

  In the liquid crystal display device of the present invention, the apparent gradation change or color tone change of the liquid crystal layer at the pressed position is canceled by voltage adjustment with respect to the original drive voltage for image display. As a result, the liquid crystal layer can display a gradation and a color tone with reduced influence of pressing, and can perform high-quality image display.

  Hereinafter, a liquid crystal display device as an embodiment of the liquid crystal display device of the present invention will be described in detail with reference to the drawings. The liquid crystal display device of the present invention is not limited to the limited configuration of the embodiments described below. As long as a pixel is displayed by applying a voltage for each display unit, another embodiment in which part or all of the configuration of each embodiment is replaced with the alternative configuration can be realized.

  In the present embodiment, an RGB color filter type color liquid crystal display device and a hybrid color liquid crystal display device will be described. However, the present invention can also be used in a liquid crystal display device that displays an achromatic image (grayscale) or a liquid crystal display device that displays a single color gradation. The illumination method of the liquid crystal layer may be a transmissive type using a backlight or a reflective type that reflects and uses incident light from the observation side. A transflective type combining a transmissive type and a reflective type may be used.

  In addition, about the manufacturing method of the liquid crystal display device shown by patent documents 1-5, a drive method, a pen input device, etc., in order to avoid the complexity of repetition, a part of illustration is abbreviate | omitted and detailed description is also abbreviate | omitted.

<First Embodiment>
1 is an explanatory diagram of a cross-sectional configuration of the liquid crystal device according to the first embodiment, FIG. 2 is an explanatory diagram of an assembly structure of the liquid crystal device, and FIG. 3 is an explanatory diagram of a state where a glass substrate is pressed with an input pen.

  As shown in FIG. 1, the liquid crystal panel 10 has two glass substrates 14 </ b> A and 14 </ b> B that have been subjected to vertical alignment processing by alignment layers 16 </ b> A and 16 </ b> B to form an overlapped panel, and a plurality of spacers 19 are set at intervals. The liquid crystal layer 17 is filled at an interval of about 5 μm. A liquid crystal material having a negative dielectric anisotropy Δε is used as the liquid crystal material of the liquid crystal layer 17. As such a liquid crystal material, MLC-6608 (registered trademark) manufactured by Merck is known. In the first embodiment, an organic film made of polyimide is used as the vertical alignment treatment of the glass substrates 14A and 14B in the present embodiment, but vertical alignment treatment using an inorganic layer such as SiOx may be performed.

  An RGB color filter layer 20 is disposed on the observation-side glass substrate 14A, and color display of one pixel is performed in three adjacent display units. The pixel shape and the color filter configuration may be changed according to the embodiment. Under the color filter layer 20, a common electrode 15 using a transparent conductive material is disposed.

  The opposite glass substrate 14B has an active matrix substrate in which a thin film transistor (TFT) is disposed under the pixel electrode 18. The pixel electrode 18 has a reflective configuration using an aluminum electrode. The pixel electrode 18 is divided for each display region 11 and an independent drive voltage is applied by a thin film transistor. On the glass substrate 14B, source lines and gate lines, which will be described later, are three-dimensionally crossed and arranged in a lattice pattern, and thin film transistor elements are arranged at respective intersections of the source lines and the gate lines.

  Between the observation-side glass substrate (color filter substrate) 14A and the polarizing plate 12, as a phase compensation plate, a broadband λ / 4 plate (a phase compensation plate that can substantially satisfy a ¼ wavelength condition in the visible light region). Is arranged. As a result, when a reflective display is performed by applying a driving voltage to the pixel electrode 18, a normally black configuration is obtained in which a dark state is obtained when no voltage is applied and a bright state is obtained when a voltage is applied.

  In the first embodiment, a reflective liquid crystal panel 10 using an active matrix substrate on which thin film transistors (TFTs) are arranged will be described. However, a panel using a simple matrix substrate and a transmissive liquid crystal having no reflective function. Similar results are obtained using panels.

  As shown in FIG. 2, the liquid crystal panel 10 has a source line side drive circuit 32 and a gate line side drive circuit 33 arranged adjacent to a display area 31 in which the display area 11 is arranged in a matrix. In the liquid crystal panel 10, the source lines 32L and the gate lines 33L are arranged in a grid pattern at the pitch of the display area 11, and a thin film transistor for driving the display area 11 is arranged at each intersection of the source lines 32L and the gate lines 33L. Has been.

  The control unit 36 controls the gate line side drive circuit 33 and the source line side drive circuit 32 to display an image on the liquid crystal panel 10. The control unit 36 outputs a drive signal to the gate line side drive circuit 33 to sequentially scan the gate lines 33L, and turns on a number of thin film transistors on the gate lines 33L according to the scan. The control unit 36 outputs a drive signal and a drive voltage to the source line side drive circuit 32, and applies a drive voltage corresponding to the display data to each of the many source lines 32L at a timing synchronized with the scanning of the gate line 33L. Output. The drive voltage is applied to the pixel electrode 18 shown in FIG. 1 through an on-state thin film transistor. The common electrode 15 and the pixel electrode 18 apply an electric field to the liquid crystal layer 17 and perform light modulation according to the magnitude of the drive voltage, whereby an arbitrary image can be output to the display region 31.

  The control unit 36 outputs the correction voltage distribution of the small area from the memory 37 to the correction circuit 38, and adjusts the driving voltage in the area where the gradation is influenced by the pressing position. The drive voltage adjusted by the correction circuit 38 is input to the source line side drive circuit 32.

  A pen input unit 34 is disposed on the display area 31 of the liquid crystal panel 10. The pen input unit 34 is a transparent thin sheet, and a large number of antennas 34X and 34Y that detect electromagnetic waves output from the pen tip of the input pen 43 are arranged. The input position coordinate calculation unit 35 detects the outputs of the multiple antennas 34 </ b> X and 34 </ b> Y and outputs the pen tip position of the input pen 43 on the plane of the pen input unit 34 to the control unit 36. The control unit 36 rewrites a part of the drive signal, and displays an image of the input pen tip position as a pointer.

  The output of the input position coordinate calculation unit 35 is input to the control unit 36 and linked to image display, so that the liquid crystal display device 1 having a position detection function using a pen input device functions. As the pen input unit 34 that can be used in the first embodiment, an electromagnetic induction type or resistance type pen type input device is known. The pen input unit 34 is disposed on the observation side of the display region 31. However, the pen input unit 34 may be disposed on the observation side with respect to the display region 31 in the resistive film method, or in the liquid crystal panel 10 in the electromagnetic induction method. You may arrange | position to the panel 10 back surface.

  FIG. 3 schematically shows a cross section of the panel when pressure is applied to the liquid crystal panel 10 by pen input. By pressing the pen tip of the input pen 43 against the liquid crystal panel 10 (pen input unit 34), the thickness of the liquid crystal layer 17 sandwiched between the two glass substrates 14A and 14B decreases with the contact point as the center. Due to the deformation of the glass substrate 14A, the alignment state of the liquid crystal molecules in the region centered on the contact point also changes. Thereby, the density of the image displayed in the area centered on the contact point is different from that before pressing.

  Therefore, the correction voltage for the display area 11 in the area affected by the pressing is stored in the memory 37, and the correction voltage is applied to the display area 11 in the area centered on the contact point. A correction voltage is added to the drive voltage applied to the display area 11 in the area centered on the detected XY coordinate position to bring the gradation of the display unit in the pressed state closer to the gradation before pressing. Whether to increase or decrease the driving voltage is determined by a combination of the material of the liquid crystal layer 17, the alignment mode, the arrangement of the polarizing plates, and the driving mode. In the first embodiment, the correction voltage map is determined by experimenting as follows.

  A driving voltage applied to the liquid crystal layer 17 when no pen is used is V1. At this time, the panel transmittance is T1. Next, when pressure is applied by bringing the pen tip of the input pen 43 into contact with the liquid crystal panel 10 in this display state, the thickness of the liquid crystal layer 17 decreases and the panel transmittance T increases or decreases. In order to match the increased or decreased panel transmittance T with the transmittance T1 before pressing, a driving voltage V2 obtained by adding the correction voltage Vdiff to the driving voltage V1 is applied to the liquid crystal layer 17 at the time of pen input. The absolute value of the correction voltage Vdiff increases as the amount of variation in the thickness of the liquid crystal layer 17 increases, and increases as the original applied voltage V1 increases.

  The correction voltage Vdiff corresponds almost one-to-one with the combination of the variation in thickness of the liquid crystal layer 17 and the original applied voltage V1. Therefore, the correction voltage at an arbitrary location on the liquid crystal panel 10 is created by creating the relationship between the planar distribution of the fluctuation amount at the time of pen input, the correction voltage, and the original applied voltage V1 on the lookup table and storing it in the memory 37. Vdiff can be taken out.

  As described above, the method of correcting the display image using the look-up table stored in advance is a special method for suppressing cell thickness fluctuations such as a special auxiliary seal portion and a partition wall structure between pixels in the liquid crystal panel 10. There is no need to create a structure. For this reason, the existing liquid crystal panel 10 can be used as it is.

  Further, in the method in which a protective plate is inserted in front of the liquid crystal panel 10 so that the pressing force of the pen tip is not applied to the pressing point of the liquid crystal panel 10, the distance between the image display surface and the pen tip by the distance between the protective plate and the gap Opens. This may cause parallax when observed from an oblique direction, and may cause an error in position designation by the pen tip. However, in the first embodiment, since the image display surface and the pen tip are in contact, such parallax can be reduced.

  As the pen input unit 34, a resistive film method disclosed in Patent Document 5 or other various electromagnetic induction methods may be used.

  The look-up table is a table in which the relative coordinates of the tip position of the input pen 43 and the drive signal level are input and the correction signal Vdiff is output. When creating the look-up table, first, the drive voltage V1 of the highest gradation (or lowest gradation) is applied to all the display areas 11, and an image of uniform gradation is displayed on the entire surface of the liquid crystal panel 10. Next, the pen tip of the input pen 43 is pressed against the liquid crystal panel 10. The pressure for pressing the input pen 43 against the liquid crystal panel 10 may be set to a value at which the thickness of the liquid crystal layer 17 is sufficiently changed at the time of pressing, and the thickness of the liquid crystal layer 17 is not reduced even if the pressure is increased further. . Next, the luminance distribution around the contact point where the pen is pressed is measured using a luminance meter. At this time, the measurement range of the luminance distribution is sufficient if it is recognized that there is no luminance variation.

  Next, the signal level of the drive voltage V1 is decreased (increased) by Δv, and the luminance distribution around the contact point is measured again in the same manner. The value of Δv may be matched with the input resolution of the DA converter of the source line side drive circuit 32. Thus, the drive voltage level is sequentially changed, and the luminance measurement is performed in a plurality of regions determined in the region where the luminance variation occurs when the input pen 43 is pressed.

  Next, the brightness measurement results with different drive voltage levels are compared, and the drive voltage Vu that is equal to the original brightness before pressing is obtained for a plurality of areas in the area where the brightness fluctuation has occurred with the drive voltage Vp. Then, the difference between the drive voltage Vp and the drive voltage Vu in the plurality of regions is stored in the lookup table as a correction signal Vdiff. By repeating this operation, a look-up table in the luminance fluctuation region centered on the pen tip is created and stored in the memory 37.

  As shown in FIG. 2, when the pressing position of the input pen 43 is input from the input position coordinate calculation unit 35 to the control unit 36 in actual use, the control unit 36 stores the gradation of the area to be corrected. The correction signal Vdiff corresponding to the gradation is supplied to the correction circuit 38. The correction circuit 38 outputs the correction signal Vdiff to the source line side drive circuit 32 at a timing synchronized with the drive signal and the drive voltage, and applies the correction signal Vdiff to a region centered on the pen tip of the input pen 43. The source line side drive circuit 32 adds the correction signal Vdiff to each drive voltage for the display area 11 in the area centered on the pen tip, and applies it to the liquid crystal layer 17 in the display area 11.

  In other words, the correction circuit 38 determines where to apply the correction signal Vdiff of the memory 37 in the display image based on the position information detected by the input position coordinate calculation unit 35. The correction signal Vdiff output from the correction circuit 38 adjusts the drive voltage input to the source line side drive circuit 32 to correct the display gradation of the display unit. Thereby, deterioration of the display image due to cell thickness fluctuation at the time of pen input can be reduced.

Second Embodiment
FIG. 4 is a flowchart of control in the control unit of the liquid crystal display device of the second embodiment. The liquid crystal display device of the second embodiment is configured in the same manner as in the first embodiment except that the input pen 43 includes a pressing force detection mechanism. Therefore, description will be made with reference to FIGS.

  As shown in FIG. 2, in the liquid crystal display device of the second embodiment, the pen tip of the input pen 43 is movable in the retracting direction against the spring bias. The movement of the pen tip moves the ferrite core disposed inside the input pen 43 within the coil, thereby changing the output frequency of the oscillation circuit using the coil.

  The input position coordinate calculation unit 35 detects the frequency of the output electromagnetic wave of the input pen 43 detected through the antennas 34X and 34Y, and detects the force with which the pen tip of the input pen 43 presses the liquid crystal panel 10. As a pen input device having such a pen pressure detection function, an electromagnetic induction pen-type input device disclosed in Patent Document 2 can be used.

  The memory 37 stores a look-up table of gradation differences before and after pressing in a plurality of regions centered on the pressing position assuming the maximum pressing force, and is directly connected to the control unit 36. The look-up table in the second embodiment includes all the display areas in the small area that are affected by pressing the correction gradation amount (for example, -10 gradations) added to the driving voltage of the display area 11 of 8-bit 256 gradations. 11 is defined in 255 ways (per original gradation value). By superimposing the center position of the small area on the pressing position and adding a correction gradation amount corresponding to the original gradation value, the gradation of the small area centered on the pressing position on the liquid crystal panel 10 is corrected. .

  The control unit 36 forms corrected image data by adding the look-up table in the memory 37 to the original image data displayed on the liquid crystal panel 10 and also performs correction according to the pressing force. Then, by generating a drive voltage from the corrected image data and inputting it to the source line side drive circuit 32, an adjusted image display is performed.

  As shown in FIG. 4, the control unit 36 captures image data to be displayed on the liquid crystal panel 10 (S11). Then, it is determined whether or not the position indicated by the input pen 43 is input from the position coordinate calculation unit 35 (S12). If the designated position is not input, the adjustment relating to the pressing of the screen is unnecessary, and the image is output as the original image data (S17). However, when the designated position is input, the gradation correction amount corresponding to the gradation of the original image data in the pressed area is read from the lookup table of the memory 37 (S13).

  Then, the pressing force input from the position coordinate calculation unit 35 is read (S14), and the gradation correction amount is multiplied by the ratio of the maximum pressing force and the pressing force to the gradation correction amount. (S15). Then, the corrected gradation data of the pressed area is added to the original image data to generate corrected image data (S16), and image display is performed using the corrected image data (S17). The corrected image data is decomposed into scanning lines, the gradation value of the driving voltage for each display area 11 is calculated, and the gradation value of the display area 11 in one column on the scanning line is converted to the source line side at a timing synchronized with the driving signal. Send to the drive circuit.

  Note that the look-up table in the memory 37 may output a correction signal Vdiff for a combination of a relative position from the pen input position, a displayed gradation level, and writing pressure information. In this case, as described in the first embodiment, with respect to a plurality of regions centered on the pressed position, the same image density adjustment can be performed using the respective correction signals Vdiff with reference to the lookup table. it can. A correction signal Vdiff for the combination of the relative position in the correction area, the original gradation level, and the writing pressure information is input to the lookup table. In actual use, the relative position in the correction area, the original gradation level, and the writing pressure information are designated so that the necessary correction signal Vdiff is obtained.

  According to the liquid crystal display device of the second embodiment, not only the position information of the input pen 43 but also the pen pressure information is used. Therefore, even when the thickness of the liquid crystal layer 17 varies due to the pen pressure variation at the time of pen input, Degradation can be reduced, and degradation of the display image can be further reduced as compared with the first embodiment.

<Third Embodiment>
FIG. 5 is an explanatory diagram of the arrangement of display units in one pixel of the liquid crystal display device of the third embodiment, and FIG. 6 is an explanatory diagram of a cross-sectional configuration of one pixel. FIG. 7 is a diagram showing the relationship between the voltage applied to the liquid crystal layer and the change in color tone, and FIG. 8 is an explanatory diagram of display in the primary color display cell and the complementary color display cell. The third embodiment is a hybrid color liquid crystal display device having a pixel filter arrangement different from that of the first embodiment. However, since the configuration and driving method of the other liquid crystal panel 50 and the circuit are almost the same as those in the first embodiment, the description will be given with reference to FIG.

  As shown in FIG. 5, in the liquid crystal panel 50 of the third embodiment, a complementary color display area 52 in which a magenta color filter layer 70M is arranged and a primary color display area 53 in which a green color filter layer 70G is arranged are arranged adjacent to each other. An image is displayed using the pixel 510 that has been selected. The pixel 51 additively mixes the display color of the complementary color display area 52 and the display color of the primary color display area 53 to display a large number of colors (hue and gradation).

  As shown in FIG. 6, in the liquid crystal panel 50, the illumination light (external light) incident from the observation-side glass substrate 64A is folded back by the reflective electrodes 68M and 68G formed on the opposite glass substrate 64B. To the observation side. A common electrode 65 common to all the display areas 52 and 53 of the liquid crystal panel 50 is disposed on the glass substrate 64A. Reflecting electrodes 68M and 68G divided for the display areas 52 and 53 are arranged on the glass substrate 64B.

  On the glass substrate 64A, a polarizing plate 62 and a broadband λ / 4 plate 63 for selectively transmitting light in a specific birefringence amount range from reciprocating transmitted light of the display regions 52 and 53 are disposed. The broadband λ / 4 plate 63 as a phase compensation plate is a phase compensation plate that can substantially satisfy the ¼ wavelength condition in the visible light region. The wideband λ / 4 plate 63 has a normally black configuration in which a dark state is displayed when no voltage is applied and a bright state is applied when a voltage is applied in the reflective display.

  On the glass substrate 64A, a magenta color filter layer 70M and a green color filter layer 70G are arranged flat, and an interface with the liquid crystal layer 67 is covered with an alignment layer 66A.

  On the glass substrate 64B, source lines 32L and gate lines 33L are arranged in a lattice pattern. Thin film transistors (TFTs) 69M and 69G for the display regions 52 and 53 are arranged at intersections of the source line 32L and the gate line 33L, and are insulated by an interlayer insulating layer 69H.

  On the interlayer insulating layer 69H, reflective electrodes 68M and 68G of aluminum electrodes imparted with diffuse reflectivity are arranged. The reflective electrodes 68M and 68G are covered with a planarization layer 68H, and an alignment layer 66B is formed on the planarization layer 68H.

  A liquid crystal layer 67 is disposed between the alignment layer 66A of the glass substrate 64A and the alignment layer 66B of the glass substrate 64B. The liquid crystal layer 67 changes the optical property (birefringence amount) according to the voltage applied between the common electrode 65 and the reflective electrodes 68M and 68G. The liquid crystal layer 67 of the complementary color display area 52 is controlled in birefringence in a chromatic area where the hue of the output light changes in addition to the achromatic area where achromatic gradation light is obtained through the polarizing plate 62. However, the amount of birefringence of the liquid crystal layer 67 in the primary color display area 53 is controlled exclusively in the achromatic color area where achromatic gradation light is obtained through the polarizing plate 62.

  The amount of birefringence of the liquid crystal layer 67 changes as shown in FIG. 7 according to the voltage applied between the common electrode 64A and the reflective electrodes 68M and 68G. The complementary color display region 52 and the primary color display region 53 change the transmittance of the liquid crystal layer 67 through the polarizing plate 62 almost continuously by a 256-level gradation voltage set in a voltage range of 0V to 3V. At this time, as shown in FIG. 8, since the green color filter layer 70G selectively transmits only green light, the primary color display area 53 displays black to green monochromatic continuous gradation. The complementary color display area 52 displays black to magenta single-color continuous gradation because the magenta color filter layer 70M selectively transmits only magenta light. Accordingly, the pixel 10 displays a continuous gradation (gray scale) of black to white by an additive color mixture of magenta light in the complementary color display area 52 and green light in the primary color display area 53.

  On the other hand, as shown in FIG. 7, the complementary color display area 52 selectively outputs red light through the polarizing plate 62 when a constant voltage of 3.8 V is applied to the reflective electrode 68M. When a constant voltage of 5V is applied to the reflective electrode 68M, blue light is selectively output through the polarizing plate 62. Therefore, as shown in FIG. 8, the pixel 10 has a green gradation output light from the primary color display area 53, a red or blue single-color output light from the complementary color display area 52, and a green gradation output light and a red or blue output light. Various intermediate colors obtained by additively mixing monochromatic output light can be displayed. Color display by mixing three primary colors of red, green and blue is possible.

  Note that the pixel 51 of the liquid crystal panel 50 can perform continuous gradation display from black to white, continuous gradation display from black to green, and continuous gradation display from black to magenta. Is only a discrete gradation display. However, practically, display quality that is comparable to continuous tone display can be obtained by performing dithering processing in which the number of light emissions in a plurality of pixel ranges is different for red and blue.

  The thickness of the liquid crystal layer 67 is 5 microns. At this time, the birefringence when the ± 5 V voltage is applied to the reflective electrodes 68M and 68G with respect to the common electrode 65 is about 300 nm. When an image is displayed on such a liquid crystal panel 50 by changing the voltage, the primary color display region 53 exhibits a change in transmittance according to the drive voltage in a region of 3 V or less, and a continuous tone characteristic is obtained. On the other hand, regarding the complementary color display region 52, blue is displayed when 5V is applied, and red is displayed when 3.8V is applied. Thus, it can be seen that the liquid crystal panel 50 of the third embodiment displays three primary colors.

  The birefringence amount R of the liquid crystal layer 67 sandwiched between the two glass substrates 64A and 64B of the liquid crystal panel 50 is expressed by R = Δneff · d according to the average birefringence Δneff and the thickness d of the liquid crystal layer. Δneff is modulated by applying a drive voltage to the reflective electrodes 68M and 68G. At this time, the amount of light passing through the liquid crystal panel 50 is a value corresponding to the value of the birefringence amount R.

  When the pen input unit 34 shown in FIG. 2 is superimposed on the liquid crystal panel 50 and pressed on the screen with the input pen 43, the thickness of the liquid crystal layer 67 changes. When the thickness of the liquid crystal layer 67 varies, the birefringence amount R is proportional to the thickness of the liquid crystal layer 67, and thus there may be unevenness in the display image according to the variation amount of the thickness. Therefore, a lookup table for correction as in the first embodiment or the second embodiment is provided, and an adjusted drive voltage different from the original drive voltage is applied to the reflective electrodes 68M and 68G. As a result, the combination of the liquid crystal panel 50 that performs hybrid color display and the drive voltage correction control using the lookup table of the memory 37 is effective. That is, even if the input pen 43 is pressed, it is possible to display an image with high quality and little disturbance near the case where the input pen 43 is not pressed.

<Liquid Crystal Display Device of Comparative Example>
In a nematic liquid crystal display device, a liquid crystal panel called an active matrix in which an active element such as a thin film transistor (TFT) is arranged in each pixel has been put into practical use. Currently, a twisted nematic (TN) mode is widely used as a nematic liquid crystal mode used in this active matrix type liquid crystal display device. Recently, a liquid crystal mode having a relatively wide viewing angle as compared with a TN mode called a VA mode or a vertical alignment mode is also used.

  Further, a hybrid mode in which coloring by a color filter and coloring by interference of birefringence are combined based on the VA mode is disclosed in Patent Document 4 as a mode with high light use efficiency.

  When a position detection device using a pen input method is stacked on such a liquid crystal panel, the liquid crystal panel is pressurized by the pressure at the time of pen input, and the thickness of the liquid crystal layer varies, or the liquid crystal orientation in the liquid crystal layer changes. Disturbance may occur and the change state of light passing through the liquid crystal layer may change. As a result, the luminance level of the display image may deviate from the assumed value, and the display quality may deteriorate. As a result, the quality of the displayed image may be deteriorated.

<Correspondence with Invention>
The liquid crystal display device 1 according to the first embodiment is disposed on a pair of glass substrates 14A and 14B disposed with a liquid crystal layer 17 therebetween, and a pair of glass substrates 14A and 14B. A pixel electrode 18 to which a drive voltage can be applied and a source line side drive circuit 32 that applies a drive voltage for each display region 11 to the pixel electrode 18 to display an image are provided. And the pen input part 34 which detects the press position on glass substrate 14A, 14B is provided, and the source line side drive circuit 32 adjusts the drive voltage in the detected press position in the direction which approaches the display state which is not pressed.

  In the liquid crystal display device 1, the apparent gradation change and color tone change of the liquid crystal layer 17 at the pressed position are canceled by voltage adjustment with respect to the original drive voltage for displaying an image. As a result, the liquid crystal layer 17 can display high-quality image display by displaying gradation and color tone with reduced influence of pressing.

  In the hybrid color liquid crystal display device of the third embodiment, two adjacent display areas 52 and 53 constitute one pixel 51, and the birefringence amount of the liquid crystal layer 67 is controlled by the chromatic color area in at least one display area 52. To do. Thereby, the pixel 51 is displayed in color.

  The liquid crystal display device 1 includes a pen input unit 34 that detects a pressed position on the glass substrate 14 </ b> A on the glass substrate 14 </ b> A disposed on the observation side of the liquid crystal layer 17. Then, a drive voltage is applied to the liquid crystal layer 17 to display an image, and a source line side drive circuit 32 that adjusts the detected drive voltage at the pressed position in a direction approaching a display state that is not pressed is provided.

  In the liquid crystal display device 1, since the center position for correction is determined using the output of the pen input unit 34 originally provided for detecting the pressed position, it is not necessary to separately provide a means for detecting the pressed position. .

  The pen input unit 34 of the liquid crystal display device 1 has a pen tip structure of the input pen 43 that detects the pressing force at the pressing position. Then, the source line side drive circuit 32 changes the adjustment amount of the drive voltage in accordance with the detected pressing force, and increases the adjustment amount when the pressing force is large compared to when it is small. Thereby, compared with the case where adjustment according to the pressing force is not performed, more accurate image display, that is, close to a state where no pressing is performed, can be performed.

  The control unit 36, the memory 37, the correction circuit 38, and the source line side drive circuit 32 of the liquid crystal display device 1 change the adjustment amount of the drive voltage according to the drive voltage for image display. When the driving voltage is large, the adjustment amount is increased as compared with the small driving voltage.

  The control unit 36, the memory 37, the correction circuit 38, and the source line side driving circuit 32 of the liquid crystal display device 1 decrease the adjustment amount stepwise toward the outside with the pressing position as the center.

  The control unit 36, the memory 37, the correction circuit 38, and the source line side driving circuit 32 of the liquid crystal display device 1 have a memory 37 that records the adjustment amounts for a plurality of areas. Then, the source line side drive circuit 32 adds the adjustment amounts of the plurality of areas recorded in the memory 37 to the drive voltage for displaying an image of the corresponding area centered on the pressed position on the glass substrate 14A. To do. Thus, the necessary adjustment can be performed simply by applying the adjustment amounts of the plurality of regions to the predetermined region centered on the pressing position, and the adjustment amount with all the coordinate positions of the liquid crystal panel 10 as the pressing position can be obtained. There is no need to prepare.

It is explanatory drawing of the cross-sectional structure of the liquid crystal device of 1st Embodiment. It is explanatory drawing of the assembly structure of a liquid crystal device. It is explanatory drawing of the state which pressed the glass substrate with the input pen. It is a flowchart of control in the control part of the liquid crystal display device of 2nd Embodiment. It is explanatory drawing of arrangement | positioning of the display unit in one pixel of the liquid crystal display device of 3rd Embodiment. It is explanatory drawing of the cross-sectional structure of one pixel. It is a diagram of the relationship between the applied voltage of a liquid crystal layer, and a color tone change. It is explanatory drawing of the display in a primary color display cell and a complementary color display cell.

Explanation of symbols

1 Liquid crystal display device 10, 50 Liquid crystal panel 11, 52, 53 Display unit (display area, complementary color display area, primary color display area)
12 Polarizing plates 14A, 14B, 64A, 64B Substrate member (glass substrate)
15, 65 Common electrode 16A, 16B Alignment layer 17, 67 Liquid crystal layer 18, 68M, 68G Electrode means (pixel electrode, reflection electrode)
19 Spacer 20, 70M, 70G Color filter layer 31 Display area 32 Drive means (source line side drive circuit)
33 Gate line side drive circuit 34 Pen input unit 35 Input position coordinate calculation unit 36 Control unit 37 Recording means (memory)
38 Correction Circuit 43 Input Pen 69M, 69G Thin Film Transistor

Claims (7)

A pair of substrate members disposed with a liquid crystal layer interposed therebetween;
Electrode means arranged on the pair of substrate members and capable of applying a driving voltage to the liquid crystal layer for each display unit;
In a liquid crystal display device comprising: a drive unit that applies an image to the electrode unit by applying a drive voltage for each display unit;
Comprising a position detecting means for detecting a pressing position on the substrate member;
The liquid crystal display device, wherein the driving means adjusts the driving voltage at the detected pressing position in a direction approaching a non-pressed display state.   Two adjacent display units constitute one pixel, and at least one of the display units controls the birefringence amount of the liquid crystal layer in a chromatic region, thereby displaying the pixel in color. The liquid crystal display device according to claim 1. In a liquid crystal display device provided with a position detection means for detecting a pressed position on the substrate member on the substrate member arranged on the observation side of the liquid crystal layer,
A liquid crystal display comprising: a driving unit that applies a driving voltage to the liquid crystal layer to display an image and adjusts the detected driving voltage at the pressed position in a direction approaching a non-pressed display state. apparatus. The position detecting means has a pressing force detecting means for detecting a pressing force at the pressing position,
The liquid crystal display device according to claim 1, wherein the driving unit changes an adjustment amount of the driving voltage in accordance with the detected pressing force.   2. The drive unit changes an adjustment amount of the drive voltage in accordance with the drive voltage for performing image display, and increases the adjustment amount when the drive voltage is large as compared to when the drive voltage is small. The liquid crystal display device of any one of thru | or 4.   6. The liquid crystal display device according to claim 1, wherein the driving unit reduces the adjustment amount stepwise toward the outside with the pressing position as a center. It has a recording means for recording the adjustment amount for each of a plurality of areas,
The drive means adds the adjustment amount of the plurality of areas recorded in the recording means to the drive voltage for displaying an image of a corresponding area centered on a pressing position on the substrate member. The liquid crystal display device according to claim 6.

Images