JP2004252231A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display capable of controlling a heating means so that a temperature at which a liquid crystal display element can operates with satisfactory responsiveness can be attained in a short period of time even at a low temperature, as the liquid crystal display provided with the heating means. <P>SOLUTION: A first temperature sensor 7 (a first temperature detecting means) is provided at the liquid crystal display element 1. A second temperature sensor 11 (a second temperature detecting means) detects heat distribution different from the heat distribution that the first temperature sensor detects. A controlling means 10 controls a sheet heater 15 (a heating member) based on first temperature information from the first temperature sensor 7 and second temperature information from the second temperature sensor 11. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a heating member for heating a liquid crystal display element.
[0002]
[Prior art]
In a conventional liquid crystal display device, when the ambient temperature is low and the temperature of the liquid crystal display element is low, the viscosity coefficient of the liquid crystal is high and the response is low. Therefore, light transmission is performed by depositing ITO (indium tin oxide) on a glass plate. There is known a device in which the liquid crystal display element is heated by a flexible sheet heater (heating member) to control the temperature of the liquid crystal display element so that desired response can be obtained. These are disclosed in Patent Document 1 and Patent Document 2.
[0003]
[Patent Document 1]
JP 2001-337313 A [Patent Document 2]
Japanese Patent Application Laid-Open No. 2002-202523
As a method of controlling the seat heater of such a liquid crystal display device, a temperature detecting means comprising a thermistor for detecting the temperature of the liquid crystal display element is provided in the liquid crystal display element, and the microcomputer outputs temperature information from the temperature detecting means. A control means for controlling the temperature of the liquid crystal display element by performing on / off control of the heater based on the temperature information to ensure good response of the liquid crystal display element at low temperatures. It is.
[0005]
[Problems to be solved by the invention]
The temperature detecting means is provided at a non-display area of the liquid crystal display element, for example, at an end of one of the pair of glass panels which is the non-display area. The sheet heater in which the glass plate is used has a characteristic that a central portion is easily heated and an end portion is hardly heated (because a glass material has low thermal conductivity and an end portion is easy to radiate heat). Also in the liquid crystal display element heated by the seat heater, the central portion which is the display area is easily heated, and the end portion is hardly heated. Therefore, a temperature difference occurs between the temperature of the display area of the liquid crystal display element and the temperature of the end of the liquid crystal display element where the temperature detecting means is provided, and the temperature of the seat heater is accurately determined. Not only cannot control be performed, but also at a low temperature of 0 ° C. or less, it takes time for the liquid crystal display element to reach a temperature for driving with good responsiveness, and the responsiveness of the liquid crystal display element is improved. There was room.
[0006]
Therefore, the present invention focuses on the above-described problem, and in a liquid crystal display device provided with a heating unit, a liquid crystal display element can reach a temperature at which a liquid crystal display element can operate with good responsiveness even in a low temperature in a short time. An object of the present invention is to provide a liquid crystal display device capable of controlling the heating means.
[0007]
[Means for Solving the Problems]
The present invention provides a liquid crystal display device including a liquid crystal display element and a heating member for heating the liquid crystal display element, as described in the liquid crystal display device according to claim 1, in order to solve the above-mentioned problem. A first temperature detecting means provided on the liquid crystal display element, a second temperature detecting means provided at a location different from the first temperature detecting means, and a first temperature detecting means provided from the first temperature detecting means. Control means for controlling the heating member based on the temperature information and the second temperature information from the second temperature detection means.
[0008]
Further, according to the present invention, in the liquid crystal display device according to claim 1, the control means stores a plurality of threshold values for turning on / off the heating means according to an ambient temperature surrounding the liquid crystal display element. And based on the second temperature information from the second temperature detecting means, performing threshold switching control for switching the thresholds of the plurality of stages, and performing the first temperature information of the first temperature detecting means. On / off control of the heating means at each threshold value based on the threshold value.
[0009]
Further, according to the present invention, in the liquid crystal display device according to claim 1 or 2, the first temperature detecting means is provided in a non-display area of the liquid crystal display element.
[0010]
According to the present invention, there is provided the liquid crystal display device according to claim 1 or 2, further comprising a case body in which the liquid crystal display element and the heating member are provided, wherein the second temperature detecting means is provided in the case body. It is stored.
[0011]
Further, according to the present invention, in the liquid crystal display device according to claim 1, the liquid crystal display element has a first liquid crystal cell and a second liquid crystal cell, and the first liquid crystal cell and the second liquid crystal cell have the same structure. The heating member is disposed between the liquid crystal cell and the liquid crystal cell.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 1 to 4 show a liquid crystal display device.
[0013]
Reference numeral 1 denotes a liquid crystal display element. The liquid crystal display element 1 includes a first liquid crystal cell 2, a second liquid crystal cell 3, and polarizing plates 4 and 5. The polarizing plate 4 is attached to the front surface of the first liquid crystal cell 2, and the polarizing plate 5 is attached to the rear surface of the second liquid crystal cell 3.
[0014]
The first liquid crystal cell 2 is one in which liquid crystal is sealed in a pair of translucent substrates 2a and 2b on which transparent electrodes are formed. The first liquid crystal cell 2 is of a so-called STN (super twisted nematic) type, and the liquid crystal display element 1 has a rectangular display area in which many pixels are arranged in a matrix.
[0015]
The second liquid crystal cell 3 has liquid crystal sealed in a pair of translucent substrates 3a and 3b, and is disposed behind the first liquid crystal cell 2. The second liquid crystal cell 3 is an interference cell that adjusts the display color tone of the liquid crystal display device 1.
[0016]
The polarizers 4 and 5 need only be at least larger than the display area. However, in order to prevent light leakage, the polarizers 4 and 5 may be substantially the same size as the front surface of the first liquid crystal cell 2 or the rear surface of the second liquid crystal cell 3. desirable.
[0017]
Reference numeral 6 denotes an FPC (flexible wiring board), one end of which is electrically connected to the first liquid crystal cell 2 of the liquid crystal display element 1 via an anisotropic conductive film, and the other end of which is a hard circuit board described later. Are electrically connected to each other through a connection member such as solder. A first temperature sensor (first temperature detecting means) 7 composed of a thermistor for detecting the temperature of the liquid crystal display element 1 is mounted in the vicinity of the connection point of the FPC 6 with the first liquid crystal cell 2. ing.
[0018]
Reference numeral 12 denotes a hard wiring board. The hard wiring board 12 includes a driving circuit 8 for driving the liquid crystal display element 1, a heater circuit 9 for driving a sheet heater described later, and a microcomputer for controlling the driving circuit 8 and the heater circuit 9. (A microcomputer), a second temperature sensor (a second temperature detecting means) 11 composed of a thermistor for detecting an ambient temperature at which the liquid crystal display element 1 is disposed, and a liquid crystal display element 1 at the rear. And a light emitting diode D that illuminates from above.
[0019]
Reference numeral 13 denotes a light diffusion plate, and the light diffusion plate 13 is provided between the liquid crystal display element 1 and the light emitting diode D. Reference numeral 14 denotes a case body, on which the liquid crystal display element 1, the FPC 6, and the hard wiring board 7 are disposed. An opening 14 a is provided in the case body 14, and the opening 14 a has a rectangular shape slightly larger than the display area of the first liquid crystal cell 2.
[0020]
Reference numeral 15 denotes a seat heater (heating member). The seat heater 15 is disposed between the first liquid crystal cell 2 and the second liquid crystal cell 3. The sheet heater 15 is formed by depositing a light-transmitting conductor 15b made of ITO on the entire surface of a light-transmitting sheet plate 15a made of a glass material (see FIG. 2). The seat heater 15 is formed to be larger than the display area of the liquid crystal display element 1, and a pair of FPCs 15 c for receiving power from the heater circuit 9 are provided at both ends thereof via an anisotropic conductive film. It is connected to the. The seat heater 15 is attached to the rear surface of the first liquid crystal cell 2 with an adhesive tape.
[0021]
Next, an electrical configuration for controlling the seat heater 15 will be described with reference to FIG. Reference numeral 10 denotes a control unit. The control unit 10 includes an A / D conversion unit 10a that converts each voltage value (temperature information) from the first and second temperature sensors 7 and 11 into a digital signal, and a liquid crystal display. ROM 10b storing a control program for driving the element 1 and a control program for the seat heater 15, which will be described in detail later, a RAM 10c for temporarily storing calculation results or set values, and a CPU 10d for executing the control program And an EEPROM 10e that stores at least threshold data described later in a control program of the seat heater 15, and the above-described units are connected by a bus. When the liquid crystal display device is mounted on, for example, a vehicle, the control unit 10 inputs the traveling information (engine speed, vehicle speed, water temperature, remaining fuel, and the like) of the vehicle to the CPU 10d, and performs various kinds of vehicle information by predetermined arithmetic processing. Then, the liquid crystal display element 1 is driven via the drive circuit 8 and the seat heater 15 is controlled to bring the liquid crystal display element 1 to the optimum driving temperature.
[0022]
Next, a control method of the seat heater 15 of the control means 10 will be described with reference to FIG. In the present embodiment, description will be made on the assumption that the optimum temperature for driving the liquid crystal display element 1 is 40 ° C.
[0023]
The control means 10 outputs the output voltage (second temperature information) from the second temperature sensor 11 after the system power supply (for example, when the liquid crystal display device is mounted on the vehicle, the ignition switch is turned on). ) Is input (step S1), and ambient temperature data (hereinafter, referred to as ambient temperature) S2 is obtained by a predetermined calculation process based on the input output voltage (step S2).
[0024]
Then, when the control means 10 obtains the ambient temperature S2, the temperature (temperature surrounding the liquid crystal display element 1) S2 in the case 14 in which the liquid crystal display element 1 is disposed is determined by any temperature condition (step) after the next step. Is selected (steps S3 to S6). In step S3, a determination is made that ambient temperature S2 <-20 ° C. In step S4, a determination is made that −20 ° C. ≦ ambient temperature S2 <0 ° C. In step S5, 0 ° C. ≦ ambient temperature S2 < A determination of 20 ° C. is made, and in step S6, a determination is made that 20 ° C. ≦ ambient temperature S2 <40 ° C.
[0025]
Next, when any one of the steps S3 to S6 is selected, the control means 10 reads the threshold data Pn (P1, P2, P3, P4) in the selected step from the EEPROM 10e and reads the first temperature sensor 7 The threshold value of the temperature data (hereinafter, referred to as panel temperature) S1 of the liquid crystal display element 1 is set (step S7). The threshold data Pn is a condition for turning on / off (heating / non-heating) the sheet heater 15 in each temperature range.
[0026]
The control means 10 inputs an output voltage (first temperature information) from the first temperature sensor 7 provided in the liquid crystal display element 1 (step S8), and based on the input output voltage, the liquid crystal display element. The first panel temperature S1 is obtained by a predetermined calculation process (step S9).
[0027]
Next, the control means 10 compares the threshold data Pn set in step S7 with the panel temperature S1 obtained in step S9 (step S10). If the panel temperature S1 is smaller than the selected threshold data Pn, In order to raise the panel temperature S1, power is supplied to the seat heater 15 via the heater circuit 9 to heat the liquid crystal display element 1 (step S11), and when the panel temperature S1 is equal to or higher than the selected threshold data Pn. Then, the power supply to the seat heater 15 is stopped (step S12).
[0028]
By repeating the above-described processing, the sheet heater 15 is turned on / off, the liquid crystal display element 1 is heated, and the panel temperature S1 gradually increases. If the temperature is equal to or higher than 40 ° C., the control unit 10 proceeds to step S13, and stops the power supply to the seat heater 15 in order to stop the control of the seat heater 15 when the temperature is low.
[0029]
In the determination of the threshold value at the ambient temperature S2, the time required for the liquid crystal display element 1 to reach the optimum driving temperature depends on the environment in which the liquid crystal display element is arranged, the housing state of the case, and the size of the display area of the liquid crystal display element 1. , The type of the liquid crystal display element 1 or the type of the seat heater 15, etc., and each temperature range (steps S3 to S6) of the second temperature sensor 11 set in a stepwise manner is different from that of the liquid crystal display element 1. It is desirable to change as appropriate depending on the use environment of the device.
[0030]
According to the present invention, when the ambient temperature is a low temperature of 0 ° C. or less, the difference between the temperature of the display area of the liquid crystal display element 1 and the temperature S1 detected by the first temperature sensor 7 is large. It is noted that the difference between the temperature of the display area of the liquid crystal display element 1 and the temperature S1 detected by the first temperature sensor 7 becomes smaller as the temperature becomes higher. There are first and second temperature sensors 7 and 11 for detecting a panel temperature S1 of the element 1 and an ambient temperature S2 at which the liquid crystal display element 1 is disposed, and the temperature gradually increases according to the ambient temperature S2. A threshold value (on / off condition of the seat heater 15) of the panel temperature S1 is set, and the threshold value is sequentially switched in accordance with the ambient temperature S2, and the seat heater 15 is determined in accordance with the panel temperature S1 detected by the first temperature sensor 7. ON / OFF system And performs.
[0031]
Therefore, if control is performed such that the ON time of the seat heater 15 is lengthened and the liquid crystal display element 1 is rapidly heated to bring the liquid crystal display element 1 to the optimal driving temperature, the liquid crystal display element 1 is overheated by the overshoot, and Although the heating temperature of the display element 1 becomes higher than the optimum driving temperature and the display contrast is reduced, the display contrast of the liquid crystal display element 1 can be reduced by controlling as described above even at a low temperature of 0 ° C. or less. , And the seat heater 15 can be controlled so as to reach the optimum driving temperature at which the liquid crystal display element 1 has excellent display responsiveness in a short time.
[0032]
Further, since the sheet heater 15 is provided between the first liquid crystal cell 2 and the second liquid crystal cell 3 of the liquid crystal display element 1, heat transfer to the first liquid crystal cell 2 in the STN liquid crystal display element 1 is performed. And good heating control becomes possible.
[0033]
Incidentally, since the polarizing plates 4 and 5 have low heat resistance, it is desirable to arrange them so as not to contact the sheet heater 15. When the second liquid crystal cell 3 (interference cell) is provided, it is desirable that a sheet heater 15 be disposed between the first liquid crystal cell 2 and the second liquid crystal cell 3. , And as close as possible to the display area of the liquid crystal display element 1.
[0034]
In the embodiment of the present invention, a liquid crystal display device in which a display area is directly viewed has been described as an example. The present invention may be applied to a liquid crystal display device in a head-up display that displays various kinds of information by being reflected to the side.
[0035]
【The invention's effect】
The present invention relates to a liquid crystal display device having a heating means for warming a liquid crystal display element, without reducing the display contrast of the liquid crystal display element, and so as to reach a temperature excellent in display response of the liquid crystal display element in a short time. It becomes possible to control the heating means.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a plan view showing a heating member of the embodiment.
FIG. 3 is a block diagram showing a liquid crystal display device of the embodiment.
FIG. 4 is a diagram showing a control method of a control unit of the embodiment.
[Explanation of symbols]
Reference Signs List 1 liquid crystal display element 2 first liquid crystal cell 3 second liquid crystal cell 7 first temperature sensor (first temperature detecting means)
10 control means 10e EEPROM (storage means)
11 Second temperature sensor (second temperature detecting means)
14 Case body 15 Seat heater (heating member)

Claims (5)

A liquid crystal display device comprising a liquid crystal display element and a heating member for heating the liquid crystal display element,
First temperature detecting means provided in the liquid crystal display element;
A second temperature detecting unit disposed at a different place from the first temperature detecting unit, first temperature information from the first temperature detecting unit, and a second temperature detecting unit from the second temperature detecting unit. A control unit for controlling the heating member based on the second temperature information. The control unit includes a storage unit storing a plurality of threshold values for turning on / off the heating unit according to an ambient temperature surrounding the liquid crystal display element, and a second temperature from the second temperature detection unit. Based on the information, threshold switching control for switching the plurality of thresholds is performed, and on / off control of the heating unit at each threshold is performed based on the first temperature information of the first temperature detecting unit. The liquid crystal display device according to claim 1, wherein: 3. The liquid crystal display device according to claim 1, wherein said first temperature detecting means is provided in a non-display area of said liquid crystal display element. 3. The liquid crystal display according to claim 1, further comprising a case body provided with the liquid crystal display element and the heating member, wherein the second temperature detecting means is housed in the case body. apparatus. The liquid crystal display element has a first liquid crystal cell and a second liquid crystal cell, and the heating member is disposed between the first liquid crystal cell and the second liquid crystal cell. The liquid crystal display device according to claim 1, wherein:

Images