Patent Publication Number: US-2011069092-A1

Title: Liquid crystal temperature sensor, temperature detecting method by liquid crystal temperature sensor, liquid crystal device and liquid crystal device drive method

Description:
TECHNICAL FIELD 
     The present invention relates to a liquid crystal temperature sensor, a method for temperature detection by a liquid crystal temperature sensor, a liquid crystal device, and a method for driving a liquid crystal device. 
     Specifically, the present invention relates to (i) a liquid crystal temperature sensor which is capable of detecting a temperature of a liquid crystal layer or a liquid crystal panel, (ii) a method for detecting a temperature of a liquid crystal layer or a liquid crystal panel by the liquid crystal temperature sensor, (iii) a liquid crystal device which can be driven by overshoot driving according to the temperature of the liquid crystal layer or the liquid crystal panel, and (iv) a method for driving the same. 
     BACKGROUND ART 
     Along with development of personal computers, television receivers, and other devices having a lighter weight and a thinner thickness, there has conventionally been a demand for display devices having a lighter weight and a thinner thickness. In order to meet this demand, flat panel displays such as liquid crystal display devices are now in wide use, in place of cathode ray tube (CRT)-based display devices. 
     Recently, the liquid crystal display devices are commonly used not only as display devices for computers but also as display devices for television receivers. Thus, there is an increasing need for displaying a moving image with the liquid crystal display devices. 
     However, the liquid crystal display device generally has a low response speed, as compared with other display devices such as CRT-based display devices. Therefore, it is not easy for the liquid crystal display device to display a moving image appropriately. 
     (OS Driving) 
     As a measure for improving the response speed, so-called overshoot driving (OS driving, overdriving) has been developed, which is a method for driving the liquid crystal display device. 
     The overshoot driving is a driving method that applies an emphasis voltage to a liquid crystal material so as to make a response of the liquid crystal material quicker, thereby improving the response speed. 
     Specifically, the overshoot driving is a method for driving the liquid crystal display device while changing a display tone for a certain pixel from a tone T 1  to another tone T 2  not simply by applying to the liquid crystal material a voltage corresponding to the tone T 2 , but by applying to the liquid crystal material an emphasis voltage which is determined in advance based on how and how much the tone T 1  is to be changed to the tone T 2 . 
     Typically, such the overshoot driving is realized by conversion of an input tone with use of a look-up table (LUT). Specifically, such a look-up table is prepared in which (i) a pair of the tone T 1  and the tone T 2  before and after a tone change is associated with (ii) a tone T 3  after conversion, and the look-up table is stored in a memory or the like. By referring to the look-up table, an input tone is converted. 
     (Temperature Dependency) 
     The liquid crystal material has quite great temperature dependency in its physical property. Therefore, the liquid crystal display device significantly changes its response speed according to a change in the temperature of the liquid crystal material. For this reason, even if such a look-up table for the overshoot driving is set with which a sufficient improvement effect in the response speed is expected at a certain temperature, the look-up table may provide an insufficient or excess improvement effect in the response speed due to a change in the temperature of the liquid crystal material. This may result in impairment in the display quality of the liquid crystal display device. 
     In view of this, as a measure for preventing the impairment in the display quality caused by the temperature change, such a technique has been developed in which a plurality of look-up tables as above are set for respective temperatures of the liquid crystal material, and a look-up table to be used is switched one from another depending on the temperature detected by a temperature sensor. Further, in association with this technique, various techniques for detecting the temperature of the liquid crystal display device have been proposed. 
     (Patent Literature 1) 
     For example, Patent Literature 1 (shown below) describes a liquid crystal display device including, for the purpose of estimating a temperature of a liquid crystal display panel more accurately, (i) a first temperature sensor provided behind a backlight unit and (ii) a second temperature sensor, provided outside a housing, which detects an outside air temperature. 
     In the liquid crystal display device of Patent Literature 1, panel temperature estimating means estimates the temperature of the liquid crystal display panel based on the respective temperatures detected by the first temperature sensor and the second temperature sensor. 
     (Patent Literature 2) 
     Patent Literature 2 (shown below) describes a liquid crystal display device including, for the purpose of detecting a temperature of the display device accurately, a temperature sensor provided in a peripheral region, which is in the outside of a display region in a liquid crystal display panel assembly. 
     CITATION LIST 
     Patent Literatures 
     [Patent Literature 1] 
     Japanese Patent Application Publication, Tokukai, No. 2007-93939 A (Publication Date: Apr. 12, 2007) 
     [Patent Literature 2] 
     Japanese Patent Application Publication, Tokukai, No. 2007-25685 A (Publication Date: Feb. 1, 2007) 
     SUMMARY OF INVENTION 
     However, the above conventional liquid crystal display devices have a problem that it is difficult for these devices to detect a temperature of the liquid crystal material accurately. 
     Furthermore, the above conventional liquid crystal display devices have a problem of increasing the number of manufacturing steps and the manufacturing cost, in manufacturing these display devices. 
     (Accurate Temperature Detection) 
     As described above, the liquid crystal display device described in Patent Literature 1 indirectly estimates the temperature of the liquid crystal material with use of the temperature sensor provided behind the backlight unit, etc. Therefore, it is difficult for this liquid crystal display device to accurately detect the temperature of the liquid crystal material. 
     (Manufacturing Cost, Etc.) 
     Further, for the liquid crystal display device described in Patent Literature 1, the temperature sensors are separately provided on the backlight unit and the like. This increases the manufacturing cost. 
     Meanwhile, in the liquid crystal display device described in Patent Literature 2, the temperature sensor is incorporated into the liquid crystal display panel. However, since the temperature sensor is additionally provided therein separately from bus lines and electrodes, which are constructions originally provided in the liquid crystal display panel, a step for providing the temperature sensor is necessary. This increases the number of manufacturing steps. 
     The present invention was made in view of the foregoing problems, and an object of the present invention is to provide (i) a liquid crystal temperature sensor which is capable of accurately detecting a temperature of a liquid crystal layer while avoiding increasing the manufacturing cost and the number of manufacturing steps and (ii) a method for temperature detection by the liquid crystal temperature sensor. 
     Further, an object of the present invention is to provide (i) a liquid crystal device which is capable of performing appropriate compensation to optical response characteristics of a liquid crystal panel even if a temperature of a liquid crystal layer or the liquid crystal panel changes and (ii) a method for driving the liquid crystal device. 
     In order to attain the foregoing objects, a liquid crystal sensor of the present invention includes: 
     a liquid crystal panel including a first substrate, a second substrate, and a liquid crystal layer sandwiched between the first substrate and the second substrate; and 
     a control section for controlling driving of the liquid crystal panel, 
     the liquid crystal panel including a plurality of picture elements arranged in a matrix, 
     the control section including a current-to-temperature information converting section for (i) detecting an amount of current flowing into at least one of the picture elements and (ii) converting the amount of current detected, into temperature information of part of the liquid crystal layer which part corresponds to said at least one of the picture elements. 
     In order to attain the foregoing objects, a method for temperature detection by the liquid crystal sensor of the present invention is a method for detecting a temperature of a liquid crystal layer in a liquid crystal temperature sensor, wherein the liquid crystal temperature sensor includes: 
     a liquid crystal panel including a first substrate, a second substrate, and the liquid crystal layer sandwiched between the first substrate and the second substrate; and 
     a control section for controlling driving of the liquid crystal panel, 
     the liquid crystal panel including a plurality of picture elements arranged in a matrix, 
     said method including the steps of: 
     detecting an amount of current flowing into at least one of the picture elements; and 
     converting the amount of current detected, into temperature information. 
     According to the above configuration and method, by detecting the amount of current flowing into said at least one of the picture elements provided in the liquid crystal panel, it is possible to detect the temperature of the liquid crystal layer. 
     Specifically, the liquid crystal layer contains a liquid crystal material, whose dielectric constant has temperature dependency. Once the dielectric constant of the liquid crystal material changes, an amount of current flowing into the liquid crystal layer, which contains the liquid crystal material, changes. Therefore, by detecting the amount of current flowing into said at least one of the picture elements, it is possible to detect the temperature of part of the liquid crystal layer which part corresponds to said at least one of the picture elements. 
     Further, according to the above configuration and method, the amount of current is detected through use of said at least one of the picture elements, which are generally provided in the liquid crystal panel. That is, the above configuration and method are realized without providing the liquid crystal panel with any additional component (e.g., a temperature sensor), which is additionally provided to the liquid crystal panel. 
     Accordingly, each of the above configuration and method detects the temperature of the liquid crystal layer with less possibility of increasing the manufacturing cost or the number of manufacturing steps. 
     Further, each of the above configuration and method detects the temperature of the liquid crystal layer based on the current flowing into the liquid crystal layer, which is the target of the temperature detection. 
     Therefore, each of the above configuration and method is capable of accurately detecting the temperature of the liquid crystal layer, unlike a configuration in which a temperature sensor, etc. for temperature detection is additionally provided at a position separated from a liquid crystal panel, for example. 
     Thus, according to the above configuration and method, it is possible to provide (i) a liquid crystal temperature sensor which is capable of accurately detecting a temperature of a liquid crystal layer while avoiding increasing the manufacturing cost and the number of manufacturing steps and (ii) a method for temperature detection by the liquid crystal temperature sensor. 
     Further, the liquid crystal sensor of the present invention can be configured such that: 
     the current-to-temperature information converting section stores information regarding a correlation between the amount of current and the temperature information; and 
     based on the information regarding the correlation, the current-to-temperature information converting section converts the amount of current detected, into the temperature information. 
     According to this configuration, the current-to-temperature information converting section for converting an amount of current to temperature information is in advance provided with information regarding a relationship between amounts of current and temperatures, in other words, tables with which amounts of current are read into temperatures. 
     This makes it possible to obtain the temperature information more accurately and smoothly. 
     Furthermore, the liquid crystal sensor of the present invention can be configured such that: 
     the first substrate includes (i) a plurality of signal lines intersecting with each other and (ii) switching elements correspondingly provided to intersections of the plurality of signal lines; 
     the plurality of signal lines include source bus lines and gate bus lines wherein the source bus lines and the gate bus lines intersect with each other at the intersections so as to be connected with the respective switching elements correspondingly; 
     the switching elements are transistor elements; 
     the control section includes (i) a source driver for controlling the source bus lines and (ii) a gate driver for controlling the gate bus lines; and 
     the current-to-temperature information converting section detects a consumption current of the source driver so as to detect the amount of current flowing into said at least one of the picture elements. 
     According to this configuration, the temperature information is obtained with use of bus lines, drivers, etc., each of which is incorporated in advance into a TFT (Thin Film Transistor) active matrix liquid crystal panel. This hardly causes a design change of the liquid crystal panel, a change in the manufacturing steps, etc. Thus, it is possible to obtain a liquid crystal sensor more easily. 
     Moreover, the liquid crystal sensor of the present invention can be configured such that: 
     the liquid crystal panel includes (i) a display region, which displays an image, and (ii) a non-display region, which does not display the image, the non-display region being provided along an outer edge of the display region; and 
     each of said at least one of the picture elements for which the amount of current is detected is a picture element belonging to the non-display region. 
     According to this configuration, said at least one of the picture elements for which the amount of current is detected belongs to the non-display region. Therefore, it is possible to apply any signal to said at least one of the picture elements, regardless of the image to be displayed on the liquid crystal panel. 
     Thus, it is possible to apply, to said at least one of the picture elements, a signal suitable for detection of the amount of current. Specifically, for example, it is possible to increase the dielectric constant of the liquid crystal material by application of a high-voltage signal in order to accurately detect the amount of current. For another example, it is possible to apply a constant-voltage signal in order to accurately figure out a change in the amount of current. 
     Thus, with the above configuration, it is possible to obtain more accurate temperature information. 
     Furthermore, the liquid crystal sensor of the present invention can be configured such that: 
     the liquid crystal panel includes (i) a display region, which displays an image, and (ii) a non-display region, which does not display the image, the non-display region being provided along an outer edge of the display region; and 
     among the picture elements, a picture element belonging to the non-display region includes, among the switching elements, a switching element connected with a corresponding dummy gate bus line, which is, among the gate bus lines, a gate bus line provided for inspection of the liquid crystal panel. 
     According to this configuration, the amount of current is detected with use of the dummy picture element, which is the picture element connected with the corresponding dummy gate bus line provided for inspection. 
     Therefore, it is possible to obtain a liquid crystal sensor more easily and with far less possibility of causing a design change of the liquid crystal panel, a change in the manufacturing steps, etc. 
     Moreover, the liquid crystal sensor of the present invention can be configured such that: 
     the second substrate includes a black matrix; and 
     the non-display region is covered with the black matrix when seen in a plane view. 
     According to this configuration, the non-display region, which includes said at least one of the picture elements for which the amount of current is detected, is covered with the black matrix. 
     Accordingly, even when any voltage is applied to said at least one of the picture elements, said at least one of the picture elements is not recognized by a main observer of the liquid crystal panel. 
     Thus, with the above configuration, it is possible to obtain accurate temperature information without impairing the display quality. 
     Furthermore, the liquid crystal sensor of the present invention can be configured such that: 
     the first substrate includes the plurality of signal lines intersecting with each other; and 
     each of the picture elements is demarcated by corresponding ones of the plurality of signal lines intersecting with each other. 
     Further, a liquid crystal device of the present invention can be a liquid crystal device including: 
     the above liquid crystal temperature sensor including the liquid crystal panel which is driven by overshoot driving according to input tone data having been subjected to tone conversion with reference to a tone conversion table, 
     the control section including: 
     a storing section for storing a plurality of tone conversion tables in which respective different degrees of tone change are set for tone conversion; 
     a selecting section for selecting, among the plurality of tone conversion tables, a tone conversion table to be referred to; and 
     a tone converting section for carrying out tone conversion on the input tone data by referring to the tone conversion table selected, 
     the selecting section selecting, among the plurality of tone conversion tables stored in the storing section, the tone conversion table which is suitable for a temperature of the liquid crystal layer, based on the temperature information supplied by the current-to-temperature information converting section. 
     Further, in order to attain the foregoing object, a method for driving the liquid crystal device of the present invention is a method for driving a liquid crystal device which includes: 
     a liquid crystal panel including a first substrate, a second substrate, and a liquid crystal layer sandwiched between the first substrate and the second substrate; and 
     a control section for controlling driving of the liquid crystal panel, 
     the liquid crystal panel including a plurality of picture elements arranged in a matrix, 
     the control section including: 
     a current-to-temperature information converting section for (i) detecting an amount of current flowing into at least one of the picture elements and (ii) converting the amount of current detected, into temperature information of part of the liquid crystal layer which part corresponds to said at least one of the picture elements; 
     a storing section for storing a plurality of tone conversion tables in which respective different degrees of tone change are set for tone conversion; 
     a selecting section for selecting, among the plurality of tone conversion tables, a tone conversion table to be referred to; and 
     a tone converting section for carrying out tone conversion on input tone data by referring to the tone conversion table selected, 
     said method including the steps of: 
     the current-to-temperature information converting section detecting an amount of current flowing into said at least one of the picture elements; 
     the current-to-temperature information converting section converting the amount of current detected, into temperature information; 
     based on the temperature information, the selecting section selecting, among the plurality of tone conversion tables stored in the storing section, a tone conversion table which is suitable for a temperature of the liquid crystal layer; 
     the converting section carrying out tone conversion on input tone data by referring to the tone conversion table selected; and 
     based on the input tone data on which the tone conversion has been carried out, driving the liquid crystal panel by overshoot driving. 
     With the above configuration and method, it is possible to determine an application voltage for overshoot driving according to accurate temperature information. 
     Therefore, even if the temperature of the liquid crystal layer changes, it is possible to perform appropriate compensation to the optical response characteristics. 
     That is, the liquid crystal material has temperature dependency in its physical property. Therefore, the liquid crystal display device has temperature dependency in its response speed. In view of this, in order that a change in the response speed of the liquid crystal display device is reduced and impairment in the display quality is prevented when the temperature of the liquid crystal material changes, it is necessary to apply to the liquid crystal layer a voltage suitable for the temperature of the liquid crystal material. 
     As a method therefor, there is so-called overshoot driving, which is previously explained. 
     In order to reduce, by means of the overshoot driving, a change in the response speed of the liquid crystal display device which change is caused by the temperature change, it is necessary to accurately grasp the temperature of the liquid crystal material, in other words, the temperature of the liquid crystal layer containing the liquid crystal material. 
     With regard to this, according to the above configuration and method, it is possible to accurately detect the temperature of the liquid crystal layer, as described previously. 
     Therefore, it is possible to set an application voltage for the overshoot driving so that the application voltage becomes more suitable for each temperature. 
     Thus, according to the above configuration and method, it is possible to provide (i) a liquid crystal device which is capable of performing appropriate compensation to optical response characteristics of a liquid crystal panel even if a temperature of a liquid crystal layer or the liquid crystal panel changes and (ii) a method for driving the liquid crystal device. 
     Further, the method for temperature detection by the liquid crystal temperature sensor of the present invention and the method for driving the liquid crystal device can be provided such that: 
     the first substrate includes (i) a plurality of signal lines intersecting with each other and (ii) switching elements correspondingly provided to intersections of the plurality of signal lines; 
     each of the picture elements is demarcated by corresponding ones of the plurality of signal lines intersecting with each other. 
     Further, in order to attain the foregoing objects, a liquid crystal sensor of the present invention can include: a liquid crystal panel including a first substrate, a second substrate, and a liquid crystal layer sandwiched between the first substrate and the second substrate; and a control section for controlling driving of the liquid crystal panel, the first substrate including (i) a plurality of signal lines intersecting with each other and (ii) switching elements correspondingly provided to intersections of the plurality of signal lines, the liquid crystal panel including a plurality of picture elements arranged in a matrix, each of the picture elements being demarcated by corresponding ones of the plurality of signal lines intersecting with each other, the control section including a current-to-temperature information converting section for (i) detecting an amount of current flowing into at least one of the picture elements and (ii) converting the amount of current detected, into temperature information of part of the liquid crystal layer which part corresponds to said at least one of the picture elements. 
     Further, the liquid crystal sensor of the present invention can be configured such that: the plurality of signal lines include source bus lines and gate bus lines wherein the source bus lines and the gate bus lines intersect with each other at the intersections so as to be connected with the respective switching elements correspondingly; the switching elements are transistor elements; the control section includes (i) a source driver for controlling the source bus lines and (ii) a gate driver for controlling the gate bus lines; and the current-to-temperature information converting section detects a consumption current of the source driver so as to detect the amount of current flowing into said at least one of the picture elements. 
     Further, a liquid crystal device of the present invention can be a liquid crystal device including: the above liquid crystal panel which is driven by overshoot driving according to input tone data having been subjected to tone conversion with reference to a tone conversion table, the control section including: a storing section for storing a plurality of tone conversion tables in which respective different degrees of tone change are set for tone conversion; a selecting section for selecting, among the plurality of tone conversion tables, a tone conversion table to be referred to; and a tone converting section for carrying out tone conversion on the input tone data by referring to the tone conversion table selected, the selecting section selecting, among the plurality of tone conversion tables stored in the storing section, the tone conversion table which is suitable for a temperature of the liquid crystal layer, based on the temperature information supplied by the current-to-temperature information converting section. 
     Further, a method for temperature detection by a liquid crystal sensor of the present invention can be a method for detecting a temperature of a liquid crystal layer in a liquid crystal temperature sensor, wherein the liquid crystal temperature sensor includes: a liquid crystal panel including a first substrate, a second substrate, and the liquid crystal layer sandwiched between the first substrate and the second substrate; and a control section for controlling driving of the liquid crystal panel, the first substrate including (i) a plurality of signal lines intersecting with each other and (ii) switching elements correspondingly provided to intersections of the plurality of signal lines, the liquid crystal panel including a plurality of picture elements arranged in a matrix, each of the picture elements being demarcated by corresponding ones of the plurality of signal lines intersecting with each other, said method including the steps of: detecting an amount of current flowing into at least one of the picture elements; and converting the amount of current detected, into temperature information. 
     Further, a method for driving a liquid crystal device of the present invention can be a method for driving a liquid crystal device, wherein the liquid crystal device includes: a liquid crystal panel including a first substrate, a second substrate, and a liquid crystal layer sandwiched between the first substrate and the second substrate; and a control section for controlling driving of the liquid crystal panel, the first substrate including (i) a plurality of signal lines intersecting with each other and (ii) switching elements correspondingly provided to intersections of the plurality of signal lines, the liquid crystal panel including a plurality of picture elements arranged in a matrix, each of the picture elements being demarcated by corresponding ones of the plurality of signal lines intersecting with each other, the control section including: a current-to-temperature information converting section for (i) detecting an amount of current flowing into at least one of the picture elements and (ii) converting the amount of current detected, into temperature information of part of the liquid crystal layer which part corresponds to said at least one of the picture elements; a storing section for storing a plurality of tone conversion tables in which respective different degrees of tone change are set for tone conversion; a selecting section for selecting, among the plurality of tone conversion tables, a tone conversion table to be referred to; and a tone converting section for carrying out tone conversion on input tone data by referring to the tone conversion table selected, said method including the steps of: the current-to-temperature information converting section detecting an amount of current flowing into said at least one of the picture elements; the current-to-temperature information converting section converting the amount of current detected, into temperature information; based on the temperature information, the selecting section selecting, among the plurality of tone conversion tables stored in the storing section, a tone conversion table which is suitable for a temperature of the liquid crystal layer; the converting section carrying out tone conversion on input tone data by referring to the tone conversion table selected; and based on the input tone data on which the tone conversion has been carried out, driving the liquid crystal panel by overshoot driving. 
     As described above, the liquid crystal sensor of the present invention includes the control section including the current-to-temperature information converting section for (i) detecting an amount of current flowing into at least one of the picture elements and (ii) converting the amount of current detected, into temperature information of part of the liquid crystal layer which part corresponds to said at least one of the picture elements. 
     Further, as described above, the method for temperature detection by the liquid crystal temperature sensor of the present invention is a method including the steps of: detecting an amount of current flowing into at least one of the picture elements; and converting the amount of current detected, into temperature information. 
     This makes it possible to provide (i) a liquid crystal temperature sensor which is capable of accurately detecting a temperature of a liquid crystal layer while avoiding increasing the manufacturing cost and the number of manufacturing steps and (ii) a method for temperature detection by the liquid crystal temperature sensor. 
     Further, as described above, a method for driving the liquid crystal device of the present invention can be a method for driving the liquid crystal device which includes the control section including: a current-to-temperature information converting section for (i) detecting an amount of current flowing into at least one of the picture elements and (ii) converting the amount of current detected, into temperature information of part of the liquid crystal layer which part corresponds to said at least one of the picture elements; a storing section for storing a plurality of tone conversion tables in which respective different degrees of tone change are set for tone conversion; a selecting section for selecting, among the plurality of tone conversion tables, a tone conversion table to be referred to; and a tone converting section for carrying out tone conversion on input tone data by referring to the tone conversion table selected, said method including the steps of: the current-to-temperature information converting section detecting an amount of current flowing into said at least one of the picture elements; the current-to-temperature information converting section converting the amount of current detected, into temperature information; based on the temperature information, the selecting section selecting, among the plurality of tone conversion tables stored in the storing section, a tone conversion table which is suitable for a temperature of the liquid crystal layer; the converting section carrying out tone conversion on input tone data by referring to the tone conversion table selected; and based on the input tone data on which the tone conversion has been carried out, driving the liquid crystal panel by overshoot driving. 
     This makes it possible to provide a method for driving a liquid crystal device, which method is capable of performing appropriate compensation to optical response characteristics of a liquid crystal panel even if a temperature of a liquid crystal layer or the liquid crystal panel changes. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram schematically illustrating a configuration of a liquid crystal temperature sensor of an embodiment of the present invention. 
         FIG. 2  is a view schematically illustrating a configuration of a liquid crystal panel of the embodiment of the present invention. 
         FIG. 3  is a view illustrating an arrangement of gate bus lines of the embodiment of the present invention. 
         FIG. 4  is a view illustrating an example of temperature dependency of a dielectric constant of a liquid crystal material. 
         FIG. 5  is a view illustrating an example of temperature dependency of a consumption current of the liquid crystal panel. 
         FIG. 6  is a flow chart illustrating how the liquid crystal temperature sensor of the embodiment of the present invention operates. 
         FIG. 7  is a flow chart illustrating how the liquid crystal temperature sensor of the embodiment of the present invention operates. 
         FIG. 8  is a block diagram schematically illustrating a configuration of a liquid crystal device of another embodiment of the present invention. 
         FIG. 9  is a flow chart illustrating how the liquid crystal device of the another embodiment of the present invention operates. 
         FIG. 10  is a block diagram schematically illustrating a configuration of a liquid crystal device of conventional art. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
     The following will explain an embodiment of the present invention with reference to  FIG. 1 .  FIG. 1  is a block diagram schematically illustrating a configuration of a liquid crystal temperature sensor of the present embodiment. 
     (Liquid Crystal Temperature Sensor) 
     As shown in  FIG. 1 , a liquid crystal temperature sensor  10  of the present embodiment includes a liquid crystal panel  30  and a control section  14 . 
     Specifically, the control section  14  includes (i) a gate driver  40  and a source driver  42  each serving as a signal line connected with the liquid crystal panel  30  and (ii) a timing controller  44  connected with the gate driver  40  and the source driver  42 . 
     Note that one of the features of the liquid crystal temperature sensor  10  of the present embodiment is that the liquid crystal temperature sensor  10  includes a current-to-temperature information converting section  50  connected with the source driver  42 . Thanks to functions of the current-to-temperature information converting section  50 , it is possible to obtain temperature information from the liquid crystal panel, particularly, from a liquid crystal layer (described later). 
     (Liquid Crystal Panel) 
     Next, the following will describe the liquid crystal panel  30  with reference to  FIG. 2 .  FIG. 2  is a view schematically illustrating a configuration of the liquid crystal panel  30 . 
     As shown in  FIG. 2 , the liquid crystal panel  30  includes (i) a first substrate  26  which serves as a TFT (Thin Film Transistor) array substrate, (ii) a second substrate  28  which serves as a color filter substrate, and (iii) a liquid crystal layer  46  sandwiched between the first substrate  26  and the second substrate  28 . 
     (First Substrate) 
     The first substrate  26  includes a plurality of gate bus lines  32  which extend along a transverse direction (the direction of the arrow X shown in  FIG. 2 ) and which are connected with the gate driver  40 . The first substrate  26  also includes a plurality of source bus lines  34  which extend along a longitudinal direction (the direction of the arrow Y shown in  FIG. 2 ) orthogonal to the transverse direction and which are connected with the source driver  42 . 
     Further, at each one of intersections of the gate bus lines  32  and the source bus lines  34 , a corresponding TFT element (transistor element), serving as a switching element  36 , is provided. 
     (Second Substrate) 
     On the other hand, the second substrate  28  includes a counter electrode  48 . 
     Further, a color filter (not illustrated) and a black matrix (not illustrated) are provided between the second substrate  28  and the counter electrode  48 . 
     (Picture Element) 
     The liquid crystal panel  30  includes substantially rectangular regions demarcated by the plurality of gate bus lines  32  and the plurality of source bus lines  34 , the substantially rectangular regions serving as respective picture elements  38 . In the liquid crystal panel  30 , the plurality of picture elements  38  are arranged in a matrix. 
     Each of the picture elements  38  includes (i) a corresponding one (1) of the switching elements  36  and (ii) a picture element electrode  39  connected with the switching element  36 . Between the picture element electrode  39  and the counter electrode  48 , the liquid crystal layer  46  is provided as described previously, and a liquid crystal capacitor C 10  is formed. 
     Note that it is not essential to provide the picture elements  38  in the respective regions demarcated by the gate bus lines  32  and the source bus lines  34 . Alternatively, for example, the picture elements  38  can be provided in respective regions extending over the corresponding gate bus lines  32 . 
     (Display Region and Non-Display Region) 
     In a case where the liquid crystal panel  30  is used as a display panel, the liquid crystal panel  30  can be divided into (i) a display region R 10 , which is a region including the center of the liquid crystal panel  30 , and (ii) a non-display region R 20 , which is located in the surrounding of the display region R 10 . 
     In the liquid crystal temperature sensor  10  of the present embodiment, the picture elements  38  are provided not only in the display region R 10  but also in the non-display region R 20 . 
     Thus, the plurality of picture elements  38  arranged in a matrix as described above can be divided into (i) picture elements  38   a  for display, which are picture elements  38  provided in the display region R 10 , and (ii) dummy picture elements  38   b , which are picture elements  38  provided in the non-display region R 20 . 
     Similarly, the plurality of gate bus lines  32  can be divided into gate bus lines  32   a  for display and dummy gate bus lines  32   b.    
     That is, as shown in  FIG. 3 , which is a view illustrating an arrangement of the gate bus lines  32 , gate bus lines  32  provided in the display region R 10  serve as the respective gate bus lines  32   a  for display, whereas gate bus lines  32  provided in the non-display region R 20  serve as the respective dummy gate bus lines  32   b.    
     The picture elements  38   a  for display are connected with the corresponding gate bus lines  32   a  for display, whereas the dummy picture elements  38   b  are connected with the corresponding dummy gate bus lines  32   b.    
     (Non-Display Region) 
     The dummy picture elements  38   b  and the dummy gate bus lines  32   b  are covered with the black matrix, which is provided in the second substrate  28 . The dummy picture elements  38   b  and the dummy gate bus lines  32   b  can be used to inspect (i) the switching elements  36  connected with the corresponding picture elements  38   a  for display, which are provided in the display region R 10 , and (ii) bus lines connected with the switching elements  36 . 
     (Temperature Detection) 
     The following will explain temperature detection carried out by the liquid crystal temperature sensor  10  of the present embodiment. 
     The liquid crystal temperature sensor  10  of the present embodiment detects, by making use of temperature dependency of a dielectric constant of a liquid crystal material and based on the consumption current of the source driver  42  monitored (detected) by the current-to-temperature information converting section  50 , a temperature of the liquid crystal panel  30 , consequently a temperature of the liquid crystal layer  46  or a temperature of a liquid crystal material contained in the liquid crystal layer  46 . These will be described below in order. 
     (Characteristics of Liquid Crystal Material) 
     First, characteristics of the liquid crystal material will be described with reference to  FIG. 4 .  FIG. 4  is a view illustrating an example of the temperature dependency of the dielectric constant of the liquid crystal material. 
     As shown in  FIG. 4 , there exists a certain relationship between (i) a panel surface temperature of a liquid crystal panel and (ii) a dielectric constant of a liquid crystal material contained in a liquid crystal layer of the liquid crystal panel. Namely, there exists a relationship that as the panel surface temperature increases, the dielectric constant of the liquid crystal material decreases. 
     Note that the panel surface temperature herein means a surface temperature of the liquid crystal panel, specifically, a temperature of the first substrate or the second substrate, each constituting the liquid crystal panel. 
     Further, the panel surface temperature of the liquid crystal panel is almost equal to a temperature of the liquid crystal layer or the liquid crystal material contained in the liquid crystal layer. This is because that (i) the liquid crystal layer is in contact with the first substrate and the second substrate of the liquid crystal panel and (ii) the liquid crystal layer is as thin as approximately several um. 
     (Consumption Current of Liquid Crystal Panel) 
     Next, the consumption current of the liquid crystal panel will be explained with reference to  FIG. 5 .  FIG. 5  is a view illustrating an example of the temperature dependency of the consumption current of the liquid crystal panel. 
     As shown in  FIG. 5 , there exists a certain relationship between (i) a panel surface temperature and (ii) a consumption current of a liquid crystal panel. That is, there exists a relationship that as the panel surface temperature increases, the consumption current of the liquid crystal panel also increases. 
     The reason why such the relationship is obtained is considered to be that as the panel surface temperature changes, in other words, as the temperature of the liquid crystal material changes, the dielectric constant of the liquid crystal material changes; consequently, the consumption current of the liquid crystal panel changes. More specifically, the reason is considered to be that a change in the dielectric constant of the liquid crystal material causes a change in the capacitances of the liquid crystal capacitors formed in part of the liquid crystal layer which part corresponds to the picture elements; consequently, an amount of current flowing into the picture elements changes. 
     According to the above relationship, by monitoring the consumption current of the liquid crystal panel, it is possible to calculate back (i) a surface temperature of the liquid crystal panel and (ii) a temperature of the liquid crystal layer or the liquid crystal material. 
     Further, as shown in  FIG. 1 , in the liquid crystal temperature sensor  10  of the present embodiment, the current-to-temperature information converting section  50  monitors a consumption current of the source driver  42  as a consumption current of the liquid crystal panel  30 . 
     Note that the current-to-temperature information converting section  50  has been supplied in advance with information regarding a relationship between (i) an amount of consumption current and (ii) a panel surface temperature of the liquid crystal panel or a temperature of the liquid crystal material (information regarding a correlation between an amount of current and temperature information (current-temperature correlation information)). 
     Therefore, the current-to-temperature information converting section  50  can convert, based on the current-temperature correlation information, a monitored consumption current into a panel surface temperature, consequently, into information regarding a temperature of the liquid crystal material, so as to output the information regarding the temperature. 
     (Operation Flow Chart) 
     Next, with reference to  FIG. 6 , the following will explain an example of an operation flow of a liquid crystal temperature sensor of the present embodiment.  FIG. 6  is a flow chart illustrating how the liquid crystal temperature sensor operates. The operation flow chart shown in  FIG. 6  illustrates a case where a liquid crystal panel included in the liquid crystal temperature sensor is used as a device for display. 
     In the example shown in  FIG. 6 , as described above, the liquid crystal panel in the liquid crystal temperature sensor is used as a device for display. Therefore, a timing controller  6   b  is supplied with a video signal (input video signal  6   a ). 
     Then, the timing controller  6   b  outputs a signal to a gate driver (output to gate driver  6   c ), and also outputs a signal to a source driver. In this operation, the signal to be outputted to the source driver varies depending on the gate bus line selected by the gate driver, since the liquid crystal temperature sensor is used also as a device for display. 
     Specifically, it is determined whether a gate bus line for display is selected or a dummy gate bus line is selected (gate driver&#39;s selection  6   d ). If the dummy gate bus line is determined to be selected, a certain signal is outputted to the source driver (output of certain signal to source driver  6   f ). 
     Note that the certain signal herein means a signal for detecting a temperature, and is different from a signal for displaying a video. The certain signal is not particularly limited, and may have a maximum voltage that the source driver can supply, for example. As the application voltage becomes higher, the dielectric constant of the liquid crystal material becomes higher. This makes it possible to more accurately monitor an amount of a current, consequently to detect the temperature accurately. 
     After the output of the certain signal to the source driver ( 6   f ), a consumption current of the source driver is monitored (monitoring of consumption current of source driver  6   g ). 
     Then, the value of the consumption current (the amount of current) thus monitored is converted into temperature information by the current-to-temperature information converting section (current-to-temperature information conversion  6   h ). Thereafter, the temperature information thus obtained is outputted (output of temperature information  6   i ). 
     On the other hand, in the determining whether a gate bus line for display is selected or a dummy gate bus line is selected (gate driver&#39;s selection  6   d ), if the gate bus line for display is determined to be selected, a usually-supplied video signal is outputted to the source driver (output of certain signal to source driver  6   e ). 
     As described above, according to the liquid crystal temperature sensor of the present embodiment, it is possible to detect the temperature by using the dummy picture elements and the dummy gate bus lines, each of which is conventionally provided for inspection, without providing any additional wiring. 
     In addition, according to the liquid crystal temperature sensor of the present embodiment, the temperature is detected by using the bus lines and the like directly formed in the first substrate, which is considered to have a temperature almost equal to that of the liquid crystal material because the first substrate is in contact with the liquid crystal material. This makes it possible to detect the temperature more accurately. 
     (Temperature Sensor) 
     Next, with reference to  FIG. 7 , the following will explain another example of an operation flow of a liquid crystal temperature sensor of the present embodiment.  FIG. 7  is a flow chart illustrating how the liquid crystal temperature sensor operates. The operation flow chart shown in  FIG. 7  illustrates a case where a liquid crystal panel included in the liquid crystal temperature sensor is used only as a temperature sensor. That is, the present liquid crystal temperature sensor is not necessarily limited to be used for display. 
     Unlike the liquid crystal temperature sensor described with reference to  FIG. 6 , the liquid crystal temperature sensor of  FIG. 7  is not used as a device for display. Therefore, the liquid crystal panel of  FIG. 7  is not divided into a display region and a non-display region, and accordingly gate bus lines thereof are not divided into gate bus lines  32   a  for display and dummy gate bus lines  32   b , either. 
     Therefore, the operation flow chart shown in  FIG. 7  does not include the “gate driver&#39;s selection  6   d ”, which is illustrated in the flow chart shown in  FIG. 6 . This is a feature of the operation flow chart shown in  FIG. 7 . The operation flow is described below. 
     In the example shown in  FIG. 7 , the liquid crystal panel in the liquid crystal temperature sensor is not used as a device for display, as described above. Therefore, a timing controller  7   b  is supplied with a certain input signal  7   a.    
     Then, the timing controller  7   b  outputs a signal to a gate driver (output to gate driver  7   c ), and also outputs a signal to a source driver. In this operation, the certain input signal is outputted to the source driver regardless of the gate bus line selected by the gate driver (output of certain signal to source driver  7   d ), since the liquid crystal temperature sensor is not used as a device for display. 
     Similarly to the flow described with reference to  FIG. 6 , after the output of the certain signal to the source driver ( 7   d ), a consumption current of the source driver is monitored (monitoring of consumption current of source driver  7   e ). 
     Then, the value of the consumption current (the amount of current) thus monitored is converted into temperature information by the current-to-temperature information converting section (current-to-temperature information conversion  7   f ). 
     Thereafter, the temperature information thus obtained is outputted (output of temperature information  7   g ). 
     Embodiment 2 
     The following will explain another embodiment of the present invention with reference to  FIGS. 8 through 10 . Note that the configuration of Embodiment 2 is the same as that of Embodiment 1 except for the features explained for Embodiment 2. For convenience of explanation, members having the same functions as those shown in the figures for Embodiment 1 are given the same signs, and are not explained here. 
     A liquid crystal device  20  of the present embodiment includes, in addition to the configuration of the liquid crystal temperature sensor  10  of Embodiment 1, an overshoot driving circuit  60 , which is provided in a control section  14 . Thus, the liquid crystal device  20  is configured so that a liquid crystal panel  30  can be driven by overshoot driving. This is a feature of the liquid crystal device  20 . The liquid crystal device  20  is described below. 
       FIG. 8  is a block diagram schematically illustrating a configuration of the liquid crystal device of the present embodiment. 
     As shown in  FIG. 8 , the liquid crystal device  20  of the present embodiment is configured to have the overshoot driving circuit  60  and EEPROM (Electrically Erasable/Programmable Read Only Memory)  70 , in addition to a liquid crystal temperature sensor which is almost the same as the liquid crystal temperature sensor  10  described with reference to  FIG. 1 . 
     That is, in the liquid crystal device  20  of the present embodiment, a video signal serving as input tone data is not directly supplied to a timing controller  44 , but is supplied to the timing controller  44  via the overshoot driving circuit  60 . 
     Specifically, the overshoot driving circuit  60  includes an overshoot driving operation section  62  (tone converting section), a LUT (Look Up Table) selecting section  64  (selecting section), and a current-to-temperature information converting section  50 . 
     The video signal is first supplied to the overshoot driving operation section  62 , and then is supplied to the timing controller  44  as an output from the overshoot driving operation section  62 . 
     In the liquid crystal device  20  of the present embodiment, a consumption current of a source driver  42  is monitored; based on the result of the monitoring, the current-to-temperature information converting section  50  obtains temperature information. In terms of this, the liquid crystal device  20  of the present embodiment is the same as the previously-described liquid crystal temperature sensor  10 . However, in the liquid crystal device  20  of the present embodiment, the temperature information outputted from the current-to-temperature information converting section  50  is supplied to the LUT selecting section  64 , which is connected with the EEPROM  70  (storing section). 
     Note that the EEPROM  70  stores, as LUTs (tone conversion tables), overshoot parameters optimum for respective temperatures of a liquid crystal material contained in a liquid crystal layer of the liquid crystal panel  30  which is to be driven. LUT 0  through LUT 3  ( 72 ) shown in  FIG. 8  indicate the LUTs for the respective temperatures. 
     Based on the temperature information supplied from the current-to-temperature information converting section  50 , the LUT selecting section  64  selects, among the plurality of LUTs  72  stored in the EEPROM  70 , a LUT  72  which is suitable for the temperature, in other words, a table to be referred to by the overshoot driving operation section  62 . 
     Note that the LUT selecting section  64  is also connected with the overshoot driving operation section  62 . Information of the LUT  72  which is selected by the LUT selecting section  64  is transmitted to the overshoot driving operation section  62 . Then, based on the LUT  72 , the overshoot driving operation section  62  outputs to the timing controller  44  a video signal that may cause optimum overshoot driving. Namely, the overshoot driving operation section  62  optimizes a degree of tone conversion by referring to the LUT  72  which is the most suitable, carries out tone conversion on the input tone data, and outputs the resulting data. 
     (Operation Flow Chart) 
     Next, with reference to  FIG. 9 , the following will explain in greater detail an example of an operation flow of the liquid crystal device of the present embodiment.  FIG. 9  is a flow chart illustrating how the liquid crystal device operates, and shows a circuit operation of the liquid crystal device which is driven by overshoot driving according to the temperature. 
     In the example shown in  FIG. 9 , the liquid crystal panel of the liquid crystal device is used as a device for display, as described above. Therefore, a timing controller  9   c  is supplied with a video signal (input video signal  9   a ). 
     Since the liquid crystal device of the present embodiment is driven by overshoot driving, the input video signal is not directly supplied to the timing controller  9   c , but is supplied to the timing controller  9   c  after being subjected to an overshoot driving process  9   b  by the overshoot driving circuit  60 . 
     Specifically, the overshoot driving for the liquid crystal device of the present embodiment is carried out according to the temperature of the liquid crystal panel or the liquid crystal material. Therefore, as described later, the overshoot driving process  9   b  is carried out according to the temperature information. 
     After being subjected to the overshoot driving process  9   b , the input video signal is supplied to the timing controller  9   c.    
     Then, the timing controller  9   c  outputs a signal to a gate driver (output to gate driver  9   d ), and also outputs a signal to a source driver. In this operation, the signal to be outputted to the source driver varies depending on the gate bus line selected by the gate driver, since the liquid crystal device is used also as a device for display. 
     Specifically, it is determined whether a gate bus line for display is selected or a dummy gate bus line is selected (gate driver&#39;s selection  9   e ). If the dummy gate bus line is determined to be selected, a certain signal is outputted to the source driver (output of certain signal to source driver  9   g ). 
     Then, after the output of the certain signal to the source driver, a consumption current of the source driver is monitored (monitoring of consumption current of source driver  9   h ). 
     Subsequently, the value of the consumption current (the amount of current) thus monitored is converted into temperature information by the current-to-temperature information converting section (current-to-temperature information conversion  9   i ). 
     Thereafter, the current-to-temperature information converting section outputs to the LUT selecting section the temperature information thus obtained. Upon receipt of the temperature information, the LUT selecting section selects, among the LUTs prepared in advance for respective temperatures, a LUT which is the most suitable for a temperature represented by the temperature information received, and then feeds the LUT back to the overshoot driving process  9   b.    
     As described previously, in the present embodiment, the overshoot driving according to the temperature is carried out. Specifically, according to the LUT thus fed back, the overshoot driving process  9   b  is carried out on the input video signal. 
     On the other hand, in the determining whether a gate bus line for display is selected or a dummy gate bus line is selected (gate driver&#39;s selection  9   e ), if the gate bus line for display is determined to be selected, a usually-supplied video signal is outputted to the source driver (output of certain signal to source driver  9   f ). 
     (Conventional Liquid Crystal Device) 
     Meanwhile, as shown in  FIG. 10 , a conventional liquid crystal device  20  which can be driven by overshoot driving includes a liquid crystal panel  30  to which a temperature sensor  100  is attached.  FIG. 10  shows conventional art, and is a block diagram schematically illustrating a configuration of the liquid crystal device. 
     Specifically, as shown in  FIG. 10 , the conventional liquid crystal device  20  driven by overshoot driving according to the temperature includes the liquid crystal panel  30  to which the temperature sensor  100  is additionally attached, as an extra component, in addition to the liquid crystal panel  30 , etc., the temperature sensor  100  detecting a temperature of the liquid crystal panel  30 . Further, in the conventional liquid crystal device  20 , after the temperature sensor  100  detects temperature information, the temperature sensor  100  outputs the temperature information so that the temperature information is supplied to a LUT selecting section  64 . 
     Since the conventional liquid crystal device  20  does not obtain the temperature information based on a current consumed by the liquid crystal panel  30 , the conventional liquid crystal device  20  does not include a current-to-temperature information converting section  50 . Thus, an overshoot driving circuit  60  of the conventional liquid crystal device  20  includes an overshoot driving operation section  62  and the LUT selecting section  64  only. 
     Upon receipt of the temperature information, the LUT selecting section  64  selects, from EEPROM  70  connected with the LUT selecting section  64 , a LUT  72  having been optimized for the temperature. 
     As described previously, the EEPROM  70  stores, as LUTs, overshoot parameters optimum for respective temperatures of a liquid crystal material which is to be driven. 
     The LUT selecting section  64  is also connected with the overshoot driving operation section  62 , and information of the LUT  72  selected by the LUT selecting section  64  is transmitted to the overshoot driving operation section  62 . Then, based on the LUT  72 , the overshoot driving operation section  62  outputs to a timing controller  44  a video signal that may cause optimum overshoot driving. 
     (Effects) 
     In the conventional configuration shown in  FIG. 10 , the temperature sensor  100  is manufactured and provided to the liquid crystal panel  30 , additionally as an extra component. Therefore, as described previously, such the conventional configuration involves problems of, e.g., (i) increasing the manufacturing cost and (ii) being incapable of accurately detecting a temperature of the liquid crystal material. 
     On the other hand, the liquid crystal device of the present invention obtains temperature information with use of bus lines, drivers, etc., each of which is incorporated in advance into the liquid crystal panel. Accordingly, an increase in the number of manufacturing steps and the manufacturing cost can be easily prevented. 
     Further, as described previously, since the liquid crystal device of the present invention obtains temperature information from part of the liquid crystal panel in which part the liquid crystal panel and the liquid crystal material are in contact with each other. This makes it easier to detect the temperature accurately. 
     (Position for Monitoring) 
     The foregoing explanation has dealt with the arrangement for monitoring an amount of current flowing into the picture elements connected with the respective dummy gate bus lines, which are provided in both of upper and lower non-display regions in the liquid crystal panel. 
     Here, how the amount of current thus monitored is dealt with is explained specifically. For example, an average value of (i) an amount of current (current on the upper side) flowing into a picture element connected with a dummy gate bus line provided in a non-display region which is close to an upper side (when viewed in the Y direction) of the liquid crystal panel and (ii) an amount of current (current on the lower side) flowing into a picture element connected with a dummy gate bus line provided in a non-display region which is close to a lower side (when viewed in the Y direction) of the liquid crystal panel can be converted into temperature information. 
     As an alternative method, for example, the following methods are considered. (i) A method for converting, into temperature information, only either one of (a) the amount of the current on the upper side and (b) the amount of the current on the lower side. (ii) A method for (a) calculating a weighted average amount of current while giving different weightings to the current on the upper side and the current on the lower side and (b) converting the value of the weighted average amount of current into temperature information. 
     Thus, it is possible to obtain, in different ways, the amount of current which is to be converted into the temperature information. Consequently, it is possible to detect the temperature and to carry out the overshoot driving appropriately according to the temperature distribution in the liquid crystal panel surface. 
     (Signal to be Applied) 
     In the case where the liquid crystal panel is not used as a device for display, the picture element for which the amount of current is to be monitored is not limited to the picture element connected with the dummy gate bus line, and may be any picture element in the liquid crystal panel, as described previously. The reason for this is as follows: In such the liquid crystal panel, it is not necessary to supply a video signal to the picture elements, and therefore it is possible to supply any signal (e.g., the previously-described certain input signal) to the picture elements. 
     On the other hand, in the case where the liquid crystal panel is used as a device for display, an amount of current flowing into the picture elements in the non-display region is monitored. This makes it possible to apply to the picture elements any signal (e.g., the previously-described certain input signal) suitable for the monitoring of the amount of current, as described previously. 
     Note that the signal to be supplied for the monitoring of the amount of current is not limited to the previously-described certain input signal, and may be any signal. However, it is preferable to apply a signal having a constant electric potential, since this makes it easier to monitor a change in the amount of current. 
     (Driving Method) 
     The foregoing has exemplified the configuration including, as the switching element, the transistor element (TFT element), which is a three-terminal element. However, the present invention is not limited to this configuration, as long as it allows active driving. Alternatively, for example, a two-terminal element such as MIM (Metal Insulator Metal) may be used as the switching element. 
     (Others) 
     Further, the foregoing has explained the configuration for monitoring, via the source driver, the amount of current which has been flown into the picture elements. However, the present invention is not limited to this configuration. Alternatively, for example, the amount of current can be monitored by other methods. 
     The present invention is not limited to the description of the embodiments above, but may be altered by a skilled person within the scope of the claims. An embodiment based on a proper combination of technical means disclosed in different embodiments is encompassed in the technical scope of the present invention. 
     INDUSTRIAL APPLICABILITY 
     According to the present invention, it is possible to detect a temperature of a liquid crystal material economically and accurately. Therefore, the present invention is applicable to liquid crystal panels which require accurate temperature information, for example, liquid crystal devices which is driven by overshoot driving. 
     REFERENCE SIGNS LIST 
     
         
         
           
               10  Liquid crystal temperature sensor 
               14  Control section 
               20  Liquid crystal device 
               26  First substrate 
               28  Second substrate 
               30  Liquid crystal panel 
               32  Gate bus line (signal line) 
               32   b  Dummy gate bus line 
               34  Source bus line (signal line) 
               36  Switching element 
               38  Picture element 
               38   b  Dummy picture element (picture element belonging to non-display region) 
               40  Gate driver 
               42  Source driver 
               46  Liquid crystal layer 
               50  Current-to-temperature information converting section 
               60  Overshoot driving circuit 
               62  Overshoot driving operation section (tone converting section) 
               64  LUT selecting section (selecting section) 
               70  EEPROM (storing section) 
               72  LUT (tone conversion table) 
             R 10  Display region 
             R 20  Non-display region