CN212675309U - Display device - Google Patents

Abstract

The utility model provides a can improve the display device who shows the grade. The display device of the present embodiment includes: a liquid crystal layer disposed in the display region; scanning lines arranged in the display region; a signal line arranged in the display region; a common electrode disposed in the display region; a pixel electrode disposed in the display region and connected to the signal line; and a controller for controlling supply of the image signal and the heating signal to the signal lines. The frequency of the heating signal is higher than that of the video signal. The controller supplies a heating signal to the signal line during a period in which the scanning line is selected.

Description

Display device

This application is based on and claims priority to japanese patent application with application number 2019-.

Technical Field

The utility model discloses an embodiment relates to display device.

Background

It is known that, in a liquid crystal display device, the response speed of liquid crystal molecules contained in a liquid crystal layer depends on the temperature of the liquid crystal layer. In general, as the temperature decreases, the response speed of the liquid crystal molecules also decreases, and thus the display quality may decrease. Therefore, in a liquid crystal display device for vehicle use, for example, which is assumed to be used in a low-temperature environment, a heater for heating a liquid crystal layer may be attached to a display panel. However, in such a liquid crystal display device, components other than the liquid crystal are also heated. In addition, it is difficult to cope with such a liquid crystal display device if only a part of the display region is heated.

SUMMERY OF THE UTILITY MODEL

An object of the present embodiment is to provide a display device capable of improving display quality.

According to one embodiment, there is provided a display device including: a liquid crystal layer disposed in the display region; scanning lines arranged in the display region; a signal line arranged in the display region; a common electrode disposed in the display region; a pixel electrode disposed in the display region and connected to the signal line; and a controller that controls supply of a video signal to the signal line and supply of a heating signal having a frequency higher than a frequency of the video signal, wherein the controller supplies the heating signal to the signal line during a period in which the scanning line is selected.

According to the above configuration, a display device capable of improving display quality can be provided.

Drawings

Fig. 1 is a plan view showing a basic configuration and an equivalent circuit of a display device of the present embodiment.

Fig. 2 is a cross-sectional view showing an example of the configuration of the display panel 2 shown in fig. 1.

Fig. 3 is a diagram showing an example of a temperature change of the liquid crystal layer when an ac voltage is applied.

Fig. 4 is a diagram showing an example of the heating signal Vheat.

Fig. 5 is a timing chart showing an example of the display mode.

Fig. 6 is a timing chart showing an example of the heating mode.

Fig. 7 is a timing chart showing an example of the two modes.

Fig. 8 is a timing chart showing another example of the two modes.

Fig. 9 is a flowchart showing an example of the heating control process of the controller 3.

Fig. 10 is a diagram showing an example of a case where the display device 1 is applied to a display device for vehicle mounting.

Detailed Description

The present embodiment will be described below with reference to the drawings. It should be noted that the disclosure is merely an example, and it is needless to say that appropriate modifications that can be easily conceived by those skilled in the art to keep the gist of the present invention are also included in the scope of the present invention. In addition, in order to make the description clearer, the width, thickness, shape, and the like of each part in the drawings are schematically shown in some cases as compared with the actual form, but the present invention is merely an example and is not limited to the explanation of the present invention. In the present specification and the drawings, the same reference numerals are given to components that perform the same or similar functions as those described with respect to the already-shown drawings, and overlapping detailed description may be omitted as appropriate.

Fig. 1 is a plan view showing a basic configuration and an equivalent circuit of a display device 1 according to the present embodiment. The display device of the present embodiment can be used for various devices such as a smart phone, a tablet terminal, a mobile phone terminal, a notebook-type personal computer, an in-vehicle device, and a game device.

The 1 st direction X, the 2 nd direction Y, and the 3 rd direction Z shown in the figure are orthogonal to each other, but may intersect at an angle other than 90 degrees. The 1 st direction X and the 2 nd direction Y correspond to directions parallel to the main surfaces of the substrates constituting the display device 1, and the 3 rd direction Z corresponds to the thickness direction of the display device 1. In the present specification, a direction toward the tip of an arrow indicating the 3 rd direction Z is referred to as "up", and a direction toward the opposite side from the tip of the arrow is referred to as "down".

The display device 1 includes a display panel 2, a controller 3, and a temperature sensor 4. The display panel 2 is, for example, an active matrix type liquid crystal display panel. In the illustrated example, the display panel 2 has a substantially rectangular shape, and has long sides 2Xa and 2Xb extending in the 1 st direction X and short sides 2Ya and 2Yb extending in the 2 nd direction Y. The shape of the display panel 2 is not limited to the illustrated example. The display panel 2 may be a polygon other than a quadrangle, or may be a shape including a curve.

The display panel 2 includes a display area DA for displaying an image and a non-display area NDA located outside the display area DA. The display region DA corresponds to a region where a liquid crystal layer functioning as a display element is provided. In the illustrated example, the non-display area NDA corresponds to a frame-shaped area surrounding the display area DA, and various drivers for controlling the display elements are arranged as described below.

The display panel 2 has a plurality of scanning lines G (G1, G2, G3, G4) and a plurality of signal lines S (S1, S2, S3) in the display area DA. In one example, the scanning lines G extend in the 1 st direction X and are arranged at intervals in the 2 nd direction Y. The signal lines S extend in the 2 nd direction Y and are arranged at intervals in the 1 st direction X. In addition, the display panel 2 has a plurality of pixels PX in the display area DA. Here, the pixels PX represent minimum units that can be individually controlled with respect to a video signal to be described later. In the illustrated example, the pixels PX are arranged in a matrix along the 1 st direction X and the 2 nd direction Y.

The pixel PX has a switching element SW, a pixel electrode PE, a common electrode CE, a holding capacitance Cs, and a liquid crystal layer LC. The switching element SW is a thin film transistor in one example, and is electrically connected to the scanning line G and the signal line S. More specifically, the switching element SW has a gate electrode, a source electrode, and a drain electrode. The gate electrode is electrically connected to the scanning line G. The source electrode is electrically connected to the signal line S, and the drain electrode is electrically connected to the pixel electrode PE. In this specification, an electrode electrically connected to the signal line S is referred to as a source electrode for convenience of description, and an electrode electrically connected to the pixel electrode PE is referred to as a drain electrode for convenience of description.

The scanning line G is connected to a switching element SW included in each of the pixels PX arranged in the 1 st direction X. The signal line S is connected to the switching element SW included in each of the pixels PX arranged in the 2 nd direction Y. When a predetermined signal is supplied to the scanning line G, the switching element SW is turned on, and various signals supplied to the signal line S are supplied to the pixel electrode PE via the switching element SW. The common electrode CE is disposed over a plurality of pixels PX and held at a common potential Vcom. The liquid crystal layer LC is driven according to an electric field formed between the pixel electrode PE and the common electrode CE. The holding capacitance Cs holds a voltage applied to the liquid crystal layer LC.

The display panel 2 has a source driver 5 and a gate driver 6 in a non-display area NDA. In the illustrated example, the source driver 5 is provided along the long side 2Xa, and the gate driver 6 is provided along the short side 2 Yb. The arrangement of the source driver 5 and the gate driver 6 is not limited to the illustrated example. For example, a plurality of gate drivers 6 may be arranged, and may be provided along both short sides 2Ya and 2 Yb. The signal lines S extend to the non-display area NDA and are connected to the source driver 5. The scanning lines G extend to the non-display area NDA and are connected to the gate driver 6.

The temperature sensor 4 is provided on a side surface of the display panel 2 in one example. The temperature sensor 4 is in contact with the display panel 2 and detects the temperature of the surface of the display panel 2. The position where the temperature sensor 4 is provided can be changed as appropriate. When detecting the temperature of the display panel 2, the temperature sensor 4 may be in contact with a part of the members constituting the display panel 2, and may be in contact with the upper surface (the surface parallel to the X-Y plane) of the display panel 2 in the non-display region NDA, for example. Alternatively, in the case where the display device 1 is, for example, a display device for mounting on a vehicle, a temperature sensor mounted on the vehicle may be used as the temperature sensor 4. In this case, the temperature sensor 4 detects an outdoor temperature, a room temperature inside the vehicle, or the like.

The controller 3 controls the source driver 5 and the gate driver 6. In the present embodiment, the controller 3 has a function of controlling heating of the liquid crystal layer LC in the display region DA in addition to a function of controlling display of an image in the display region DA. For example, the controller 3 controls the operation of the display device 1 in a display mode in which a video is displayed in the display area DA, a heating mode in which the liquid crystal layer LC is heated, and a dual mode in which display and heating are performed simultaneously. The controller 3 performs switching of the display mode, the heating mode, and the two modes, for example, based on the temperature detected by the temperature sensor 4. For example, in the case where the temperature detected by the temperature sensor 4 is the 1 st temperature T1 or less, the controller 3 selects the heating mode. For example, in the case where the temperature detected by the temperature sensor is higher than the 1 st temperature T1 and equal to or lower than the 2 nd temperature T2, the controller 3 selects the dual mode. For example, in the case where the temperature detected by the temperature sensor is higher than the 2 nd temperature T2, the controller 3 selects the display mode.

In the display mode, the controller 3 supplies a video signal Vsig to the signal line S. More specifically, the controller 3 generates a control signal CTs for controlling the source driver 5 and a control signal CTg for controlling the gate driver 6 based on video data or the like supplied from an external device, and outputs the signals to the source driver 5 and the gate driver 6, respectively. The gate driver 6 sequentially supplies a gate signal Vg for selecting the scanning line G to the scanning line G based on the control signal CTg received from the controller 3. The source driver 5 generates a video signal Vsig corresponding to the gradation of the pixel PX based on the control signal CTs received from the controller 3, and supplies the video signal Vsig to the plurality of signal lines S. Hereinafter, the time interval between the sequential selection of the scanning lines G and the supply of the video signal Vsig to the same signal line S is referred to as 1 frame.

In the heating mode, the controller 3 supplies a heating signal Vheat to the signal line S. More specifically, the controller 3 generates a heating control signal Chs for controlling the source driver 5 and a heating control signal Chg for controlling the gate driver 6 based on, for example, the temperature detected by the temperature sensor 4, and outputs the generated signals to the source driver 5 and the gate driver 6, respectively. The gate driver 6 supplies a gate signal Vg for selecting a scanning line G to a predetermined scanning line G for a predetermined time based on the heating control signal Chg received from the controller 3. The source driver 5 generates a heating signal Vheat based on the heating control signal Chs received from the controller 3, and supplies the heating signal Vheat to a predetermined signal line S during a period in which the scanning line G is selected. In the heating mode, the controller 3 may select all the scanning lines G and supply the heating signal Vheat to all the signal lines S, or may select a specific scanning line G and supply the heating signal Vheat to the specific signal line S.

In the two-dimensional mode, the controller 3 supplies both the video signal Vsig and the heating signal Vheat to the signal line S. More specifically, in the two-stage mode, the controller 3 sets a driving period for supplying the video signal Vsig and a heating period for supplying the heating signal Vheat within 1 frame. During the driving period, the controller 3 performs the same control as in the display mode. During the heating period, the controller 3 performs the same control as the heating mode. The controller 3 supplies the common electric potential Vcom to the common electrode CE in any of the display mode, the heating mode, and the two modes.

In the illustrated example, the controller 3 is disposed outside the display panel 2. The controller 3 is mounted on, for example, a flexible circuit board connected to the display panel 2. The controller 3 may be mounted to the display panel 2 in part or in whole.

Fig. 2 is a cross-sectional view showing an example of the configuration of the display panel 2 shown in fig. 1. Here, a cross-sectional view of the display panel 2 along the 1 st direction X and the 3 rd direction Z is shown. The display panel 2 has a 1 st substrate SUB1 and a 2 nd substrate SUB 2. The 1 st substrate SUB1 and the 2 nd substrate SUB2 face each other in the 3 rd direction Z, and a liquid crystal layer LC is held therebetween. In one example, the display panel 2 is a transmissive type having a transmissive display function of selectively transmitting light from the lower side of the 1 st substrate SUB1 to display an image. The display panel 2 may be either a reflective type having a reflective display function of selectively reflecting light from above the second substrate SUB2 to display an image or a semi-transmissive type having both a transmissive display function and a reflective display function.

The 1 st substrate SUB1 includes an insulating substrate 10, insulating layers 11, 12, and 13, a signal line S, a common electrode CE, a pixel electrode PE (PE1, PE2, and PE3), an alignment film AL1, and the like. The insulating substrate 10 is formed of a transparent insulating material such as glass or resin. The insulating layer 11 is formed on the insulating substrate 10. A semiconductor layer of a scanning line or a switching element, not shown, is located between the insulating substrate 10 and the insulating layer 11. The signal line S is formed on the insulating layer 11 and covered with the insulating layer 12. The common electrode CE is formed on the insulating layer 12 and covered with the insulating layer 13. The pixel electrode PE is formed on the insulating layer 13 and covered with the alignment film AL 1. The pixel electrodes PE are disposed in the 1 st direction X in regions between adjacent signal lines S, and face the common electrodes CE, respectively. In the illustrated example, each of the pixel electrodes PE has a slit ST.

The scanning line and the signal line S are formed of a metal material such as molybdenum, tungsten, titanium, or aluminum, and may have a single-layer structure or a multi-layer structure. The pixel electrode PE and the common electrode CE can be formed of a transparent conductive material such as Indium Tin Oxide (ITO). The insulating layer 11 is an inorganic insulating layer such as silicon nitride (SiN) or silicon oxide (SiO), and may be a single-layer film composed of any one of these layers or a multilayer film in which a plurality of inorganic insulating layers are stacked. The insulating layer 12 is an organic insulating layer formed of acryl resin or the like. The insulating layer 13 is an inorganic insulating layer formed of silicon nitride (SiN).

The 2 nd substrate SUB2 includes an insulating substrate 20, a light-shielding layer 21, a color filter layer 22, an overcoat layer 23, an alignment film AL2, and the like. The insulating substrate 20 is formed of a transparent insulating material such as glass or resin. The light shielding layer 21 is a resin colored black in one example, and is provided on the surface of the insulating substrate 20 facing the 1 st substrate SUB 1. The light-shielding layer 21 faces each of the signal lines S to partition each pixel PX. The color filter layer 22 covers the light-shielding layer 21 and is also in contact with the insulating substrate 20. The color filter layer 22 includes, for example, a red color filter CF1, a green color filter CF2, and a blue color filter CF 3. The color filters CF1, CF2, and CF3 are opposed to the pixel electrodes PE1, PE2, and PE3, respectively. The overcoat layer 23 covers the color filter layer 22. The overcoat layer 23 is formed of a transparent resin. The orientation film AL2 covers the overcoat layer 23.

The color filter layer 22 may be provided on the 1 st substrate SUB 1. The color filter layer 22 may include 4 or more color filters. A white color filter may be disposed in the pixel PX for displaying white color, a non-colored resin material may be disposed, or the overcoat layer 23 may be disposed without disposing a color filter.

The liquid crystal layer LC is enclosed between the alignment film AL1 and the alignment film AL 2. The alignment films AL1 and AL2 are, in one example, horizontal alignment films that align liquid crystal molecules in a direction parallel to the main surfaces of the insulating substrates 10 and 20. The orientation of liquid crystal molecules contained in the liquid crystal layer LC is controlled by an electric field formed between the common electrode CE and the pixel electrode PE. The polarization of light transmitted through the display panel 2 is controlled by controlling the orientation of the liquid crystal molecules.

The display panel 2 is located between the 1 st optical element OD1 containing the polarizing plate PL1 and the 2 nd optical element OD2 containing the polarizing plate PL 2. The 1 st optical element OD1 is located below the 1 st substrate SUB1 in the illustrated example. The 2 nd optical element OD2 is located above the 2 nd substrate SUB2 in the illustrated example. The 1 st optical element OD1 and the 2 nd optical element OD2 may include a phase difference plate as necessary.

The display panel 2 shown in the figure mainly has a configuration corresponding to a display mode using a lateral electric field almost parallel to the main surface of the substrate. The display panel 2 may have a configuration corresponding to a display mode using a vertical electric field perpendicular to the substrate main surface, an electric field in an oblique direction oblique to the substrate main surface, or a combination of these electric fields. In a display mode using a vertical electric field or an oblique electric field, for example, a configuration in which the 1 st substrate SUB1 includes one of the pixel electrode PE and the common electrode CE, and the 2 nd substrate SUB2 includes the other of the pixel electrode PE and the common electrode CE can be applied. The substrate main surface here is a main surface of the insulating substrates 10 and 20, and is a surface parallel to the X-Y plane.

Fig. 3 is a diagram showing an example of a temperature change of the liquid crystal layer when an ac voltage is applied. Fig. 3 shows the temperature of the liquid crystal material in the case where an alternating voltage of a frequency different from that of the liquid crystal materials A, B, C and D of 4 was applied under the condition that the room temperature was 26 degrees. The liquid crystal materials A, B, C and D constitute a display panel as a liquid crystal layer, and an ac voltage is applied between the common electrode CE and the pixel electrode PE. The liquid crystal materials A and B are fluorine-based liquid crystal materials, and the liquid crystal materials C and D are cyano-based liquid crystal materials. The temperature of the liquid crystal material herein is a measured value measured by a temperature sensor provided on the surface of the display panel.

As shown in fig. 3, the frequency of the applied ac voltage is in the range of 50kHz to 10MHz, and the temperatures of all the exemplified liquid crystal materials A, B, C and D rise higher than room temperature. More specifically, in the frequency range of 50kHz to 500kHz, the temperature of the liquid crystal materials A, B, C and D increases with an increase in frequency. In the range of 10MHz or less where the frequency is higher than 500kHz, the temperatures of the liquid crystal materials A, C and D are almost constant. As described above, the temperatures of the liquid crystal materials A, B, C and D show almost the same frequency dependence regardless of the types thereof.

Fig. 4 is a diagram showing an example of the heating signal Vheat. Fig. 4 shows the heating signal Vheat and the video signal Vsig in the two-dimensional mode as an example. Fig. 4 shows the potentials of the pixel electrode PE when the potentials of the heating signal Vheat and the video signal Vsig are based on the common potential Vcom of the common electrode CE.

In the present embodiment, the heating signal Vheat is an ac signal. The frequency of the heating signal is higher than the frequency of the video signal Vsig. The frequency of the heating signal is, for example, 500kHz or more and 1MHz or less. Here, the frequency of the video signal Vsig corresponds to the reciprocal of 1 frame. The frequency of the video signal Vsig is 60Hz in one example. When the heating signal Vheat is supplied to the pixel electrode PE through the signal line S, an ac voltage is applied between the pixel electrode PE and the common electrode CE. Therefore, as described with reference to fig. 3, the liquid crystal layer LC is heated by the ac voltage.

In the illustrated example, the amplitude Ah of the heating signal Vheat is larger than the amplitude As of the video signal Vsig. By setting the amplitude Ah in this manner, a higher heating effect can be obtained. The amplitude Ah may be the same As the amplitude As. In one example, the amplitude Ah is 5V or more and 10V or less.

As described above, in the two-frame mode, there are both the heating period in which the heating signal Vheat is supplied and the driving period in which the video signal Vsig is supplied for 1 frame. In the illustrated example, the heating period is set before the driving period in each frame. In the two-mode, the heating period is shorter than the driving period. More specifically, the heating period is preferably short enough that the liquid crystal molecules contained in the liquid crystal layer LC do not respond to the electromagnetic field formed by the heating signal Vheat. The heating period is 1ms in one example. Note that the timing at which the heating period is set in each frame is not limited to the illustrated example. For example, the heating period may be set after the driving period in each frame.

In the illustrated example, the polarities of the heating signal Vheat and the picture signal Vsig are reversed for each frame. That is, in the 1 st frame, the heating signal Vheat has a positive polarity at the start time point of the heating period and a negative polarity at the end time point of the heating period. On the other hand, in the 2 nd frame, the heating signal Vheat has a negative polarity at the start time point of the heating period and a positive polarity at the end time point of the heating period. The video signal Vsig has a positive polarity in the 1 st frame and a negative polarity in the 2 nd frame.

Next, the operations of the display mode, the heating mode, and the two modes will be described with reference to fig. 5 to 8. Fig. 5 to 8 show potentials of the scanning lines G1, G2, G3, and G4 and potentials of the signal lines S1, S2, and S3.

Fig. 5 is a timing chart showing an example of the display mode.

First, the controller 3 controls the gate driver 6 to supply a high-level gate signal Vg to the scanning line G1. Thereby, the scanning line G1 is selected. At this time, the controller 3 controls the source driver 5 to supply the video signal Vsig corresponding to each of the signal lines S1, S2, and S3. In the illustrated example, the controller 3 supplies the positive-polarity video signal Vsig to each of the signal lines S1, S2, and S3. The potential of the video signal Vsig corresponds to the gradation of each pixel PX.

Next, the controller 3 controls the gate driver 6 to supply a high-level gate signal Vg to the scanning line G2. Thereby, the scanning line G2 is selected. At this time, the controller 3 controls the source driver 5 to supply the video signal Vsig corresponding to each of the signal lines S1, S2, and S3. In the illustrated example, the controller 3 supplies a negative-polarity video signal Vsig to each of the signal lines S1, S2, and S3. The potential of the video signal Vsig corresponds to the gradation of each pixel PX.

Similarly, the controller 3 controls the gate driver 6 to sequentially supply the high-level gate signal Vg to the scanning lines G3 and G4. Thereby, the scanning lines G3 and G4 are sequentially selected. The controller 3 controls the source driver 5 to supply a corresponding video signal Vsig to each of the signal lines S1, S2, and S3. In the illustrated example, the controller 3 supplies the positive video signal Vsig to each of the signal lines S1, S2, and S3 in synchronization with the selection of the scanning line G3, and supplies the negative video signal Vsig to each of the signal lines S1, S2, and S3 in synchronization with the selection of the scanning line G4.

Through the above steps, the writing of 1 frame is completed. Writing is performed in the same manner in the next frame, but the polarity of the video signal Vsig is reversed. That is, in the next frame, the negative video signal Vsig is supplied to each of the signal lines S1, S2, and S3 when the scanning lines G1 and G3 are selected, and the positive video signal Vsig is supplied to each of the signal lines S1, S2, and S3 when the scanning lines G2 and G4 are selected. In the illustrated example, the holding period for holding the video signal Vsig is set in the frame, but the holding period may be omitted.

Fig. 6 is a timing chart showing an example of the heating mode. In the example shown in fig. 6, the controller 3 heats the entire display area DA. That is, the controller 3 controls the gate driver 6 to supply the high-level gate signal Vg to all of the scanning lines G1, G2, G3, and G4 at a predetermined timing. Thus, the scanning lines G1, G2, G3, and G4 are selected at predetermined times. The controller 3 controls the source driver 5 during a period in which the high-level gate signal Vg is supplied to the scan lines G1, G2, G3, and G4, that is, during a period in which the scan lines G1, G2, G3, and G4 are selected, and continues to supply the heating signal Vheat to all of the signal lines S1, S2, and S3. Therefore, in the heating mode, the alternating voltage is continuously applied between the pixel electrode PE and the common electrode CE. In other words, in the heating mode, the heating of the liquid crystal layer LC is continued for a period in which the scanning line G is selected.

In the heating mode, the heating time for supplying the heating signal Vheat is 1 frame or more. The heating time is 100 seconds in one example. The heating time can be appropriately changed according to the temperature detected by the temperature sensor 4, for example. In the illustrated example, the controller 3 may heat the entire display area DA, but the controller 3 may locally heat the display area DA by selecting a specific scanning line G and supplying the heating signal Vheat to a specific signal line S.

Fig. 7 is a timing chart showing an example of the two modes. In the illustrated example, the heating period is provided before the driving period in each frame.

During the heating period, the controller 3 performs the same control as the heating mode shown in fig. 6 to heat the liquid crystal layer LC. In the illustrated example, the controller 3 heats the entire display area DA. That is, the controller 3 continuously supplies the high-level gate signal Vg to all the scan lines G1, G2, G3, and G4 during the heating period. During this period, the scan lines G1, G2, G3, and G4 are selected. Further, the controller 3 continues to supply the heating signal Vheat to all of the signal lines S1, S2, and S3 while the scan lines G1, G2, G3, and G4 are selected.

Next, in the driving period, the controller 3 performs control similar to the display mode shown in fig. 5 to write the video signal Vsig to each pixel PX. That is, the controller 3 sequentially supplies the high-level gate signal Vg to the scanning lines G1, G2, G3, and G4, and sequentially selects the scanning lines G1, G2, G3, and G4. The controller 3 supplies the corresponding video signals Vsig to the signal lines S1, S2, and S3 in synchronization with the selection of the scanning lines G1, G2, G3, and G4, respectively.

As described above, the controller 3 performs writing of the video signal Vsig to the pixels PX after heating of the liquid crystal layer LC in each frame. In the illustrated example, the gate signal Vg is supplied to the scanning line G1 continuously from the heating period to a part of the driving period in the same frame, and the gate signal Vg is supplied to the scanning line G4 continuously from a part of the driving period to the heating period in the next frame.

As described with reference to fig. 4, the heating period is 1ms in one example. Therefore, even if the heating period is set in the frame, the liquid crystal molecules do not respond to the electromagnetic field formed by the heating signal Vheat, and therefore, the display of the image in the driving period is not affected. Therefore, in the two-mode, the heating of the liquid crystal layer LC and the display of an image are performed in two steps within 1 frame.

Fig. 8 is a timing chart showing another example of the two modes. The example shown in fig. 8 is different from the example shown in fig. 7 in that the display area DA is locally heated during the heating period. In the illustrated example, during the heating period, the high-level gate signal Vg is supplied to the scan lines G1 and G2 to select the scan lines G1 and G2, but the scan lines G3 and G4 are not selected. In the illustrated example, the heating signal Vheat is supplied to the signal lines S1 and S3, but is not supplied to the signal line S2. Therefore, the heating signal Vheat is supplied to the pixel electrode PE of the pixel PX including the switching element SW connected to the scanning lines G1 and G2 and the signal lines S1 and S3.

In the example shown in fig. 8, an image is displayed in the entire display area DA during the driving period. However, the area where the image is displayed during the driving period may coincide with the area heated during the heating period. That is, during the drive period, the controller 3 may select the scanning line G (in the example shown in fig. 8, the scanning lines G1 and G2) selected during the heating period, and supply the video signal Vsig to the signal line S (in the example shown in fig. 8, the signal lines S1 and S3) to which the heating signal Vheat is supplied during the heating period.

Fig. 9 is a flowchart showing an example of the heating control process of the controller 3.

In step 901, the controller 3 determines whether or not the temperature T detected by the temperature sensor 4 is equal to or lower than the 1 st temperature T1. The 1 st temperature T1 is, for example, -10 ℃. When the detected temperature T is equal to or lower than the 1 st temperature T1, the process proceeds to step 902.

In step 902, the controller 3 performs control of the heating mode. That is, the controller 3 selects all the scanning lines G, and supplies the heating signal Vheat to all the signal lines S during the period when the scanning lines G are selected.

In step 903, the controller 3 determines whether a predetermined time has elapsed. If the predetermined time has not elapsed, the determination of step 903 is repeated. When the predetermined time has elapsed, the process returns to step 901.

If the temperature T detected in step 901 is higher than the 1 st temperature T1, the process proceeds to step 904. In step 904, the controller 3 determines whether the detected temperature T is equal to or lower than the 2 nd temperature T2. The 2 nd temperature T2 is, for example, 0 ℃. When the detected temperature T is equal to or lower than the 2 nd temperature T2, the process proceeds to step 905.

In step 905, the controller 3 performs the control of the two modes. That is, the controller 3 sets the heating period and the driving period within 1 frame. During the heating period, the controller 3 selects a predetermined scanning line G, and supplies the heating signal Vheat to a predetermined signal line S during the period in which the scanning line G is selected. In the drive period, the controller 3 sequentially selects the scanning lines G and supplies the corresponding video signals Vsig to the signal lines S in synchronization with the selection of the scanning lines G.

In step 906, the controller 3 determines whether a predetermined number of frames have elapsed. If the predetermined number of frames have not elapsed, the determination of step 906 is repeated. If the predetermined number of frames have elapsed, the process returns to step 904.

In step 904, when the detected temperature T is higher than the 2 nd temperature T2, the process proceeds to step 907. In step 907, the controller 3 controls the display mode. That is, the controller 3 sequentially selects the scanning lines G and supplies the corresponding video signals Vsig to the signal lines S in synchronization with the selection of the scanning lines G.

Further, the heating control process of the controller 3 is not limited to the above-described example. For example, after the display mode is selected, the controller 3 may select the heating mode or the dual mode again based on the temperature T detected by the temperature sensor 4. In the heating mode, the controller 3 may select a specific scanning line G and supply the heating signal Vheat to a specific signal line S. In addition, the 1 st temperature T1 and the 2 nd temperature T2 are not limited to the above-described examples. The 1 st temperature T1 and the 2 nd temperature T2 may be set as appropriate depending on the position where the temperature sensor 4 is provided, for example, as long as the condition that the 2 nd temperature T2 is higher than the 1 st temperature T1 is satisfied.

Fig. 10 is a diagram showing an example of a case where the display device 1 is applied to a display device for vehicle mounting. In the example shown in fig. 10, the display panel 2 displays a speedometer Ms showing the speed of the automobile, a tachometer Mr showing the rotational speed of the engine, and the like. The controller 3 switches the heating mode, the two-stage mode, and the display mode based on the temperature T detected by the temperature sensor 4, thereby setting the presence or absence of generation of the heating signal Vheat, the range in which the heating signal Vheat is supplied in the display area DA, and the length of time for which the heating signal Vheat is supplied.

For example, when the temperature T detected by the temperature sensor 4 is-10 ℃ or lower, the controller 3 selects the heating mode to heat the entire display area DA when the vehicle is stopped in the idling state. During this period, the display panel 2 does not display an image.

If the temperature T is higher than-10 deg.c or in the case of a vehicle being in motion, the controller 3 selects, for example, the two-phase mode. During the heating period, the controller 3 selectively heats the display region having a high priority for displaying information required during traveling. For example, in fig. 10, the controller 3 supplies the heating signal Vheat to a region where the speedometer Ms and the tachometer Mr are displayed. That is, the controller 3 selects the scanning line G corresponding to the region where the speedometer Ms and the tachometer Mr are displayed, and supplies the heating signal Vheat to the signal line S corresponding to the region where the speedometer Ms and the tachometer Mr are displayed for each frame. The length of the heating period is, for example, 1 ms. At this time, the controller 3 displays an image on the entire display panel 2 during the driving period. Although there is a possibility that a display other than the area to which the heating signal is applied is delayed in display due to the temperature, display information necessary for traveling is heated in the display area to appropriately secure a temperature environment, and thus display can be performed without the influence of the display delay.

If the temperature T is higher than 0 ℃, for example, the controller selects the display mode. That is, the controller 3 stops the supply of the heating signal Vheat, and sets only the driving period for each frame in the entire display panel 2 to display an image.

According to the present embodiment, the controller 3 supplies the ac heating signal Vheat to the signal line S, thereby applying an ac voltage to the liquid crystal layer LC and heating the liquid crystal layer LC. Therefore, even when the temperature of the use environment of the display device 1 is low, the response speed of the liquid crystal molecules can be increased, and the display quality can be improved. In addition, according to the present embodiment, the liquid crystal layer LC can be directly heated by applying an ac voltage between the pixel electrode PE and the common electrode CE. Therefore, the liquid crystal layer LC can be heated efficiently, and heating of other components than the liquid crystal layer LC can be suppressed. Therefore, deterioration and the like due to heating of other members can be suppressed. Further, since the position of the heated display region can be set arbitrarily, in the example of fig. 10, the present embodiment can be realized by disposing the positions of the speedometer Ms and the tachometer Mr at arbitrary positions, and a high degree of freedom in design can be ensured.

Further, according to the present embodiment, since the liquid crystal layer LC is heated by supplying various signals to the scanning lines G and the signal lines S, the heating region and the heating time can be set according to the temperature of the use environment of the display device 1. For example, when the temperature of the use environment is low, the heating mode supplies the heating signal Vheat for a sufficient time, so that the liquid crystal layer LC can be heated efficiently. When the temperature of the liquid crystal layer LC rises to some extent, for example, in the two-dimensional mode, the heating period is set to be short, for example, about 1ms, so that the liquid crystal layer LC can be heated without disturbing the display during the driving period. Further, by selectively supplying the heating signal Vheat to a region with a high priority of display, it is possible to perform smooth display while suppressing power consumption. As described above, according to the present embodiment, a display device capable of improving display quality can be provided.

Further, although several embodiments of the present invention have been described, these embodiments are illustrative and are not intended to limit the scope of the present invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope equivalent to the invention described in the scope of claims.

Claims (9)

1. A display device is characterized by comprising:

a liquid crystal layer disposed in the display region;

scanning lines arranged in the display region;

a signal line arranged in the display region;

a common electrode disposed in the display region;

a pixel electrode disposed in the display region and connected to the signal line; and

a controller for controlling the supply of the image signal and the heating signal to the signal lines,

the frequency of the heating signal is higher than that of the image signal,

the controller supplies the heating signal to the signal line during a period in which the scanning line is selected.

2. The display device according to claim 1,

the frequency of the heating signal is 500kHz or more and 1MHz or less.

3. The display device according to claim 1,

the heating signal has an amplitude equal to or greater than an amplitude of the video signal.

4. The display device according to claim 1,

a heating period for outputting the heating signal and a driving period for outputting the video signal are provided for 1 frame.

5. The display device according to claim 4,

the heating period is shorter than the driving period.

6. The display device according to claim 1,

the length of time for outputting the heating signal is 1 frame or more.

7. The display device according to any one of claims 1 to 6,

there is also a temperature sensor for detecting the temperature,

the controller determines whether to generate the heating signal based on a detection result of the temperature sensor.

8. The display device according to any one of claims 1 to 6,

there is also a temperature sensor for detecting the temperature,

the controller sets a range in which the heating signal is supplied in the display area based on a detection result of the temperature sensor.

9. The display device according to any one of claims 1 to 6,

there is also a temperature sensor for detecting the temperature,

the controller sets a length of time for which the heating signal is output based on a detection result of the temperature sensor.

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